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	2022-12-14: How Can Matter Be BOTH Liquid AND Gas? 12:57: Unlike other exotic states, supercritical fluids can be found on Earth. 13:01: Or, rather, in the Earth. 13:17: It’s rare on Earth, but if you lived on Venus you wouldn’t think of the supercritical fluid as a fringe state of matter at all. 17:53: So crazy to me that an observatory at the south pole observes the northern hemisphere sky because it needs the Earth to be in the way.
	2022-12-08: How Are Quasiparticles Different From Particles? 15:32: ... can watch documentaries that explore cosmic ideas – titles like "Other Earths: The Search for Habitable Exoplanets," “Planet Hunting with the James ...
	2022-11-23: How To See Black Holes By Catching Neutrinos 09:41: They are natural particle accelerators, far more powerful than the ones we can build on earth. 15:58: Feynstein 100 asks if stable heavy elements like the island of stability could exist, then shouldn't they be present on earth and be found already?
	2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table? 03:43: But technetium is so unstable that by the time the Earth pulled itself together from the detritus of dead stars, all the technetium was long gone. 12:28: ... can make these, but unless that production process is ongoing on the Earth, like with Carbon-14, short-lived unstable elements are extremely rare in ... 19:26: So if this dynamic happened on earth it makes sense it could happen across the universe. 20:20: Just like life on earth probably did. 03:43: But technetium is so unstable that by the time the Earth pulled itself together from the detritus of dead stars, all the technetium was long gone.
	2022-11-09: What If Humanity Is Among The First Spacefaring Civilizations? 01:23: Named for Nikolaus Copernicus, who showed that the Earth is NOT the center of the universe, as previously thought. 05:18: ... Earth that involved the first formation of self-replicating cells, the ... 07:07: ... estimated that the Earth will only be habitable for another 1 billion years, after which the sun ... 07:17: So Earth will have 5 billion habitable years in total. 07:45: There might be other habitable planets that last a lot longer than the Earth. 08:39: After all, why should all life have the same requirements as Earth life? 09:25: ... only short-lived planets like Earth are habitable and there are few hard steps, then we were born at a ... 11:36: When we look at life on Earth, it seems that life has a common tendency to aggressively expand into new territories and niches. 12:27: But if they’re too common, then we couldn’t have evolved in the first place as Earth would have already been colonised. 13:19: Instead, if we assume they move very fast, then we wouldn’t see them until they basically arrive on Earth. 08:39: After all, why should all life have the same requirements as Earth life?
	2022-10-26: Why Did Quantum Entanglement Win the Nobel Prize in Physics? 01:31: You put the first box in a rocket and send it to the moon, while you keep the second box with you on Earth. 17:42: ... if we can find some that have other   commonalities with Earth -  similar age system, similar heavy element abundances, maybe ... 17:37: The report talks about Earth-mass planets around Sun-like stars, of which there are plenty.
	2022-10-12: The REAL Possibility of Mapping Alien Planets! 00:33: ... molecules in the atmospheres of exoplanets a bit larger than the Earth. JWST   will even take images of some exoplanets. ... 07:45: ... we need, our spacecraft can’t start their outward journey from the Earth - they   needs to get closer to the Sun first. This is ... 09:31: ... spacecraft starts out by launching  backwards compared to Earth’s orbital direction,   using sails to slow down and sort of tack ... 10:07: ... entire dance will have to be performed without any guidance from Earth due to the   several day light travel time back to Earth. As ... 12:52: ... time, the image that the train of spacecraft sends back to Earth will get clearer and clearer.   It should be possible to ... 07:45: ... we need, our spacecraft can’t start their outward journey from the Earth - they   needs to get closer to the Sun first. This is how ... 00:33: ... molecules in the atmospheres of exoplanets a bit larger than the Earth. JWST   will even take images of some exoplanets. But those images will ... 09:31: ... spacecraft starts out by launching  backwards compared to Earth’s orbital direction,   using sails to slow down and sort of tack ... 10:07: ... wider and more diffuse the further you go.   The column for an Earth-sized exoplanet at 100 LY is only 1.3 km across, so this really is ... 06:05: ... Like,10 times the distance  of Pluto, or well over 500 times the Earth’s   orbital radius. Around 550 “astronomical  units” or “AUs” in ...
	2022-09-21: Science of the James Webb Telescope Explained! 03:28: JWST now sits at the Earth’s second Lagrange point, its mirrors fully unfolded and its infrared instruments humming along nicely. 11:26: ... amazing images and even more amazing science that’s sure to flow in from Earth’s Lagrange 2 point over the next years as the James Webb Space Telescope ... 03:28: JWST now sits at the Earth’s second Lagrange point, its mirrors fully unfolded and its infrared instruments humming along nicely. 11:26: ... amazing images and even more amazing science that’s sure to flow in from Earth’s Lagrange 2 point over the next years as the James Webb Space Telescope ...
	2022-08-24: What Makes The Strong Force Strong? 15:35: They recently did an episode on the iconic Blue Marble photograph of Earth and the legend of how NASA changed the Apollo 17 mission to capture it.
	2022-08-17: What If Dark Energy is a New Quantum Field? 03:33: ... this, if you could take all the dark energy in a space the size of the earth and convert it to mass by E=mc^2, you’d only get about a grain of sand’s ... 08:36: ... in the world was made of the four Aristotlean elements, water, earth, fire, and air, while another fifth element called quintessence filled ...
	2022-08-03: What Happens Inside a Proton? 15:29: ... scales, and that example is plate tectonics.   The Earth’s upper mantle is mostly solid on scales less than around a ...
	2022-07-27: How Many States Of Matter Are There? 13:18: ... and culture, and how these changes may affect humanity and all life on Earth. ...
	2022-06-30: Could We Decode Alien Physics? 00:00: ... the perhaps not too distant future, every radio telescope on Earth receives the same massive data   dump from what can only be an ... 15:41: ... to stop.  Where as the energy to accelerate can be based back on Earth. ... 00:00: ... the perhaps not too distant future, every radio telescope on Earth receives the same massive data   dump from what can only be an advanced ...
	2022-06-22: Is Interstellar Travel Impossible? 02:35: ... be accelerated to 20% light speed by a giant array of lasers back on earth. ... 05:35: ... plane - and maybe we blast a path ahead with lasers or something from Earth. ... 07:34: Think about a satellite or meteoroid entering the Earth’s atmosphere.
	2022-06-01: What If Physics IS NOT Describing Reality? 14:22: ... above and below the plane of the disk slightly.   Life on Earth has persisted for billions of years,  so it’s survived various ...
	2022-05-25: The Evolution of the Modern Milky Way Galaxy 12:11: ... supernova waves   may not be the best thing for life on Earth, but  we do have 2 billion years to get ready for ... 15:56: Some of you pointed out other  possible explanations for the   Fermi paradox and the specialness of Earth. 16:02: ... Nicholson and others remind us that  the Earth’s moon is exceptionally large,   and such large moons are ... 12:11: ... supernova waves   may not be the best thing for life on Earth, but  we do have 2 billion years to get ready for ... 15:22: ... Now that’s true. There’s a good reason to restrict ourselves to Earth-like systems when we do these   calculations of the abundance of ... 16:02: ... and such large moons are probably very  rare even if Earth-mass planets are   common. The large moon has been proposed ...
	2022-05-18: What If the Galactic Habitable Zone LIMITS Intelligent Life? 00:24: ... and sustaining life, as we discussed  in our episode on the rare earth hypothesis.   But if you want life, one of the  only ... 02:52: ... one story,   Tamanuitera travels too quickly around the  Earth, and humans complain that the days are   too short. His foster ... 03:40: ... - the smaller ones became terrestrial   planets like the Earth, while the larger collected  vast atmospheres of hydrogen and helium ... 05:52: ... But those elements are critical -  they’re what planets like the Earth are made   out of. So firstly a star needs to form  from ... 00:24: ... and sustaining life, as we discussed  in our episode on the rare earth hypothesis.   But if you want life, one of the  only non-negotiable ... 04:32: ... Kepler also revealed that there are around 40  billion Earth-analog planets in the Galaxy,   that means rocky or terrestrial ... 09:08: ... Jupiter-like planets probably wouldn’t  stand a chance at forming Earth-analogs. ... 13:03: ... galaxy - even if just with robotic  probes. But it seems that most earth-analogs have   a head start of a billion years - more than  ... 04:32: ... Kepler also revealed that there are around 40  billion Earth-analog planets in the Galaxy,   that means rocky or terrestrial planets in ... 09:08: ... Jupiter-like planets probably wouldn’t  stand a chance at forming Earth-analogs. ... 13:03: ... galaxy - even if just with robotic  probes. But it seems that most earth-analogs have   a head start of a billion years - more than  ... 04:32: ... for life,   even if we assume that life can  only form on Earth-like ... 02:52: ... slowly across the sky. Little did the Maori   know that Earth's days ARE getting longer,  but it's because of the moon, not the ... 05:52: ... giants like Jupiter - and that can also  cause trouble for smaller Earth-sized ...
	2022-05-04: Space DOES NOT Expand Everywhere 02:24: ... and latitude and the coordinate system of the 2-D surface of the Earth, a metric in GR is the coordinate system of a chunk of spacetime with 3 ... 02:38: ... and longitude describe the spherical geometry of the surface of the Earth, the FLRW metric gives the geometry or shape of the universe. The spatial ...
	2022-03-23: Where Is The Center of The Universe? 00:25: ... imagined the earth the center of the cosmos until Nicolaus Copernicus shoved us from our ... 03:04: General relativity can be used to calculate the spacetime curvature produced by the Earth or the Sun to determine their gravitational effects. 13:51: ... almost certainly not true, but no one is ever going to prove that the earth, humanity, even you personally, are not at the very center of a very ... 14:59: ... experience might be ideal for life due to the rich biodiversity of Earth’s intertidal ... 15:27: But even if life didn’t start in tidal pools on Earth, who’s to say it couldn’t have happened that way elsewhere? 15:52: On Earth, tectonic activity is essential for life due to its role in the carbon cycle. 16:07: Without that recycling Earth would have frozen due to the absence of greenhouse effect. 13:51: ... almost certainly not true, but no one is ever going to prove that the earth, humanity, even you personally, are not at the very center of a very non-Copernican ... 15:52: On Earth, tectonic activity is essential for life due to its role in the carbon cycle. 18:31: ... clearly associated with stars and had radio frequency spacing similar to Earthly ... 14:59: ... experience might be ideal for life due to the rich biodiversity of Earth’s intertidal ...
	2022-03-08: Is the Proxima System Our Best Hope For Another Earth? 00:16: But never imagined that he was gazing on a   multi-star system the stellar that  hosted a world much like the Earth. 01:28: ... astronomers to watch alpha-cen sway relative to the background stars as Earth orbited the ... 01:55: Perhaps they also bore planetary systems - and even planets like the Earth. 02:05: But our greatest hope of another Earth isn’t with the twins. 02:39: For the entire history of humanity that orbit has placed this red dwarf closer to the earth than its companions. 06:18: Such a short orbital period, combined with the star’s mass, gave them an orbital radius for the exoplanet of around 20 times smaller than the Earth’s. 07:01: It’s practically the same as the Earth’s. 07:47: Proxima C is much bigger than it’s earth-like neighbour, at 7 times earth’s mass. 08:02: ... prospective Proxima D is just a quarter of Earth mass and orbits once every 5 days, well inside the orbit of Proxima B. ... 08:58: But Proxima B is almost certainly real, and so weirdly similar to the Earth. 09:27: The simplest case is for the length of the planet’s day to be the same as its year - both 11.2 earth days. 11:55: Auroras which may even be visible from Earth by a near-future telescope. 15:31: ... Webb telescope, the largest and most powerful telescope to ever leave Earth, turned in its first photo of outer ... 09:27: The simplest case is for the length of the planet’s day to be the same as its year - both 11.2 earth days. 02:05: But our greatest hope of another Earth isn’t with the twins. 08:02: ... prospective Proxima D is just a quarter of Earth mass and orbits once every 5 days, well inside the orbit of Proxima B. That’s ... 01:28: ... astronomers to watch alpha-cen sway relative to the background stars as Earth orbited the ... 15:31: ... Webb telescope, the largest and most powerful telescope to ever leave Earth, turned in its first photo of outer ... 07:47: Proxima C is much bigger than it’s earth-like neighbour, at 7 times earth’s mass. 06:18: Such a short orbital period, combined with the star’s mass, gave them an orbital radius for the exoplanet of around 20 times smaller than the Earth’s. 07:01: It’s practically the same as the Earth’s. 07:47: Proxima C is much bigger than it’s earth-like neighbour, at 7 times earth’s mass. 08:36: ... - a Neptunish body may have been imaged around Rigel Kentaurus and an Earth-sized body may have transited Toliman on an orbit that would fry it to a ...
	2022-02-16: Is The Wave Function The Building Block of Reality? 00:03: ... of multiple realities. But there’s one explanation that feels as down to earth as the classical world that we’re trying to explain. Let’s see if it ...
	2022-01-27: How Does Gravity Escape A Black Hole? 02:36: It would take 8 minutes for us to notice the sudden darkness, and the Earth would continue to orbit the now-empty patch of space for the same time. 03:42: ... example, when Earth feels the pull of the Sun’s gravity - it’s not directly interacting with ...
	2022-01-12: How To Simulate The Universe With DFT 14:43: ... we have the one about black holes puncturing the Earth, and then the one about how we might search for Dyson spheres or other ... 14:53: We told you that an asteroid-mass, atom-sized black hole would pass straight through the earth if it impacted. 15:14: The minimum velocity it could have on reaching the Earth is the solar system’s escape velocity at Earth’s orbit, or around 42 km/s. 15:23: The the fast-moving black hole slows-down inside the Earth because exchanges momentum with or eats stationary material on its way through. 15:49: Either way, it’ll still have solar system escape velocity after the passage through the earth and we would never see it again. 15:57: ... where the black hole had multiple interactions on its way to the Earth - perhaps it punctured the Sun, swung around Jupiter, etc, and lost ... 16:08: But it would need to reach Earth’s surface moving at 10 or so km/s to get stuck in the planet - perhaps after a couple of passes. 15:57: ... where the black hole had multiple interactions on its way to the Earth - perhaps it punctured the Sun, swung around Jupiter, etc, and lost speed ... 15:14: The minimum velocity it could have on reaching the Earth is the solar system’s escape velocity at Earth’s orbit, or around 42 km/s. 16:08: But it would need to reach Earth’s surface moving at 10 or so km/s to get stuck in the planet - perhaps after a couple of passes. 15:14: The minimum velocity it could have on reaching the Earth is the solar system’s escape velocity at Earth’s orbit, or around 42 km/s. 16:08: But it would need to reach Earth’s surface moving at 10 or so km/s to get stuck in the planet - perhaps after a couple of passes.
	2021-12-29: How to Find ALIEN Dyson Spheres 00:00: In our search for alien lifeforms we scan for primitive biosignatures, and wait and hope for their errant artificial signals to happen by the Earth. 00:44: ... satisfy humanity’s current energy needs by covering a tiny fraction of Earth’s surface with solar cells. And we should probably do that by the ... 00:56: Not by covering the entire Earth, but by building solar collectors in space. 01:00: ... were to cover the entire sphere surrounding the Sun with the radius of Earth’s orbit, we’d collect all of the Sun’s light - a billion times more than ... 02:38: Earth’s biosphere is already a pretty good planet-scale solar collector. 02:42: If you were to observe Earth from a distant solar system, you might notice that it looks strangely dark. 03:17: And Earth’s biosphere - mostly its forests - absorb a fraction of that light and use it to power biological processes. 03:36: ... star you’d have to have an incredibly sensitive telescope to pick the Earth’s faint glow from the Sun’s overwhelming ... 00:44: ... satisfy humanity’s current energy needs by covering a tiny fraction of Earth’s surface with solar cells. And we should probably do that by the ... 01:00: ... were to cover the entire sphere surrounding the Sun with the radius of Earth’s orbit, we’d collect all of the Sun’s light - a billion times more than ... 02:38: Earth’s biosphere is already a pretty good planet-scale solar collector. 03:17: And Earth’s biosphere - mostly its forests - absorb a fraction of that light and use it to power biological processes. 03:36: ... star you’d have to have an incredibly sensitive telescope to pick the Earth’s faint glow from the Sun’s overwhelming ... 02:38: Earth’s biosphere is already a pretty good planet-scale solar collector. 03:17: And Earth’s biosphere - mostly its forests - absorb a fraction of that light and use it to power biological processes. 03:36: ... star you’d have to have an incredibly sensitive telescope to pick the Earth’s faint glow from the Sun’s overwhelming ... 01:00: ... were to cover the entire sphere surrounding the Sun with the radius of Earth’s orbit, we’d collect all of the Sun’s light - a billion times more than what ... 00:44: ... satisfy humanity’s current energy needs by covering a tiny fraction of Earth’s surface with solar cells. And we should probably do that by the ...
	2021-12-20: What Happens If A Black Hole Hits Earth? 00:12: ... just a matter of time before a black hole finally found its way to the Earth. So that part might actually ... 00:29: ... it - but there’s no possibility of it ever coming close enough to the Earth to cause trouble here. We know there are plenty of these “stellar mass” ... 04:01: ... given enough time some of them will quite literally cross paths with the earth. ... 04:26: ... what happens if a black hole hits the Earth? It turns out this is actually a scientifically very useful question. So ... 05:13: ... At interstellar speeds it spends around a minute passing through the Earth. Given that size and speed, our Phobos-mass black hole might consume a ... 08:05: ... 1970s to suggest that maybe this was a black hole punching through the earth. ... 08:16: ... there was only one shockwave detected in the Earth’s atmosphere, and a black hole’s exit on the other side of the planet ... 08:51: ... the passage of the black hole through the Earth itself might still be detected. This black hole bullet would generate a ... 09:03: ... seismic waves would reach all points on the Earth’s surface. Even at the lowest mass possible for a primordial black hole it ... 09:24: ... the smallest PBH masses, there may only be one black hole hitting the earth every million years. For the Phobos-mass black holes or larger, you may ... 10:16: ... neither the earth’s atmosphere nor its surface would keep a good record of micro black holes ... 12:24: ... yet been done. OK guys, to wrap up- have any black holes ever hit the earth? We don’t know. We probably wouldn’t have noticed if they had. Finding a ... 04:26: ... around the size of an atom. And it would be moving fast when it hit the earth - it must have fallen in from interstellar space, and so should be ... 10:16: ... its surface would keep a good record of micro black holes hitting the earth. Earth’s dynamic interior and its eroding atmosphere would quickly erase the tiny ... 09:03: ... from a regular earthquake because it would be felt across the entire Earth surface. ... 08:16: ... there was only one shockwave detected in the Earth’s atmosphere, and a black hole’s exit on the other side of the planet ... 08:51: ... be detected. This black hole bullet would generate a shockwave through Earth’s mantle like a supersonic Mach ... 09:03: ... seismic waves would reach all points on the Earth’s surface. Even at the lowest mass possible for a primordial black hole it ... 10:16: ... neither the earth’s atmosphere nor its surface would keep a good record of micro black holes ... 08:16: ... there was only one shockwave detected in the Earth’s atmosphere, and a black hole’s exit on the other side of the planet should have made ... 10:16: ... neither the earth’s atmosphere nor its surface would keep a good record of micro black holes hitting ... 08:51: ... be detected. This black hole bullet would generate a shockwave through Earth’s mantle like a supersonic Mach ... 09:03: ... seismic waves would reach all points on the Earth’s surface. Even at the lowest mass possible for a primordial black hole it will ...
	2021-12-10: 2021 End of Year AMA! 00:02: ... 2021 um which makes me think maybe there's something wrong with the earth's gravitational field time seems to be passing more quickly actually ...
	2021-11-10: What If Our Understanding of Gravity Is Wrong? 08:08: What on earth does that mean, you ask?
	2021-10-20: Will Constructor Theory REWRITE Physics? 05:31: ... a geodesic through spacetime, which results in it falling towards the Earth. ...
	2021-10-05: Why Magnetic Monopoles SHOULD Exist 13:24: ... - typically using cosmic ray observatories - or contributing to the Earth’s magnetic field - and in a number of other ...
	2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe 01:42: ... neutron star fields are a billion  times stronger than those of the earth or ... 02:00: ... is very different from  the magnetized space around the earth or sun.   It’s filled with electrons and  positrons. ... 02:35: ... is a little fuzzy. We’re seeing the star’s  atmosphere. Similar to Earth’s atmosphere,   this layer of haze starts out  very tenuous ... 03:27: ... while Earth’s atmosphere is something like 100 km thick, depending on how you ... 06:38: ... a neutron star. Where the star is 50 billion  times the density of earth, we might find a   nucleus like Zinc-80, which would decay ... 07:06: ... at least a trillion times the density of matter   on Earth. We are really relying on our theoretical calculations here - we’re ... 08:15: ... deep, densities have reached   100 trillion times that of the Earth. Here, the once-distinct nuclei are beginning to touch each other As ... 10:06: ... nuclear pasta weighs as much as a mountain on   Earth. As the neutron star rotates, these buried neutron star mountain ... 11:14: ... The density is here is 200 trillion  times anything found on Earth. ... 12:23: ... these plasmas have been seen in   collider experiments on Earth, we’re not sure if they exist in neutron stars. The only other ... 02:35: ... is a little fuzzy. We’re seeing the star’s  atmosphere. Similar to Earth’s atmosphere,   this layer of haze starts out  very tenuous ... 03:27: ... while Earth’s atmosphere is something like 100 km thick, depending on how you ... 02:35: ... denser as we drop.  But the similarities end there.   Earth’s atmosphere is mostly oxygen and nitrogen in molecular form. Pressure increases ... 03:27: ... while Earth’s atmosphere is something like 100 km thick, depending on how you define the ... 02:35: ... is a little fuzzy. We’re seeing the star’s  atmosphere. Similar to Earth’s atmosphere,   this layer of haze starts out  very tenuous - almost a ...
	2021-09-07: First Detection of Light from Behind a Black Hole 01:38: ... an image resolution equivalent to a telescope the size of the planet earth. ...
	2021-08-10: How to Communicate Across the Quantum Multiverse 16:27: ... This is believed to be one source of cosmic rays that reach the earth. The magnetic fields then go on to add to the galaxy’s magnetic ...
	2021-08-03: How An Extreme New Star Could Change All Cosmology 03:19: ... magnetic fields. Fields around a billion times stronger than the earth or sun’s magnetic field. That’s at the top tier of the most magnetic ... 05:01: ... to stars is with stellar parallax. That’s when the motion of the Earth causes a star to appear to move relative to more distant stars. Until ... 05:51: ... a white dwarf the mass of our sun would be around the size of the earth, this new guy is barely 25% bigger than the moon, making it the smallest ... 17:08: ... be clear - the electric universe pseudo-theory is about as valid as flat earthism - it’s just dressed up a bit nicer. But I don’t want to get all negative ...
	2021-07-21: How Magnetism Shapes The Universe 00:14: So just tilt your compass 90 degrees and you can continue your journey - either down to the molten iron dynamo surrounding the Earth’s core, or up. 00:43: Threads tugged lightly towards the Earth, tightly towards the Sun, or into inescapable knots towards black holes. 03:23: ... while most of the Earth’s dipole field loops back - but some of those field lines connect to this ... 03:44: But while we’re here, it’s worth following one of Earth’s field lines that connects directly to the surface of the Sun. 03:59: The Earth’s solid inner core and mantle regulate the flow in its liquid outer core, resulting in a clean dipole field. 05:36: ... mapped how bursts of solar wind material were reflected back towards the Earth from the edge of the ... 08:58: ... the Earth’s dynamo, swirls of magma are induced by the coriolis force, and while ... 09:10: These amplify what starts out as a very weak and disordered field into the ordered and powerful field that surrounds the Earth. 13:29: ... have to factor in his personal magnetism when they calculate the Earth’s geomagnetic ... 00:43: Threads tugged lightly towards the Earth, tightly towards the Sun, or into inescapable knots towards black holes. 00:14: So just tilt your compass 90 degrees and you can continue your journey - either down to the molten iron dynamo surrounding the Earth’s core, or up. 03:23: ... while most of the Earth’s dipole field loops back - but some of those field lines connect to this ... 03:44: But while we’re here, it’s worth following one of Earth’s field lines that connects directly to the surface of the Sun. 03:59: The Earth’s solid inner core and mantle regulate the flow in its liquid outer core, resulting in a clean dipole field. 08:58: ... the Earth’s dynamo, swirls of magma are induced by the coriolis force, and while ... 13:29: ... have to factor in his personal magnetism when they calculate the Earth’s geomagnetic ... 00:14: So just tilt your compass 90 degrees and you can continue your journey - either down to the molten iron dynamo surrounding the Earth’s core, or up. 03:23: ... while most of the Earth’s dipole field loops back - but some of those field lines connect to this greater ... 08:58: ... the Earth’s dynamo, swirls of magma are induced by the coriolis force, and while these are ... 03:44: But while we’re here, it’s worth following one of Earth’s field lines that connects directly to the surface of the Sun. 13:29: ... have to factor in his personal magnetism when they calculate the Earth’s geomagnetic ... 03:59: The Earth’s solid inner core and mantle regulate the flow in its liquid outer core, resulting in a clean dipole field.
	2021-06-23: How Quantum Entanglement Creates Entropy 13:44: ... syndrome - the exponential buildup of space junk around the earth. And then the one about the Plank   length - the smallest ... 18:54: ... here all the gurgling and screaming that must wreath the earth at all times. Small ...
	2021-06-09: Are We Running Out of Space Above Earth? 01:36: The quickest low-altitude orbits circle the Earth 16 times a day. 01:45: ... And while a loose screw or paint chip may not be all that scary on earth, at orbital speeds of 7 km/s they can carry as much energy as a ... 04:17: Below around 1000 km, Earth’s atmosphere is incredibly diffuse but still present. 05:41: I already mentioned that orbits decay due to interaction with the upper reaches of Earth’s atmosphere. 06:03: Satellites in low earth orbit may need to be boosted a few times a year to prevent this inspiral. 08:08: They quickly smear out in a ring around the Earth, making tracking and avoidance that much more difficult. 11:21: The Kessler syndrome accelerates, churning up low earth orbit into a cloud of shrapnel. 11:29: Some sci-fi writers like to present Kessler syndrome as an impassable maelstrom, a giant space blender, effectively imprisoning us on the Earth. 11:54: Higher orbits, like medium earth orbit where the GPS satellites live, will probably also be okay due to the relative low density up there. 12:02: ... to high altitudes- maybe they could be destroyed in collisions in low earth orbit, creating a train of debris that wreaks havoc higher ... 12:13: But the real risk is for anything trying to stay in low earth orbit. 12:33: We’ll have to curb our appetite for global digital communication for at least several years while we wait for the junk field to fall back to Earth. 12:42: After about a decade, very low earth orbit - up to 400km - will become usable again. 12:59: ... trash to fall faster, or even electromagnetic tethers which push on earth’s magnetic field to deorbit a ... 13:14: ... to maintain our cosmic front yard, and continue our safe use of Earth’s orbital space ... 01:36: The quickest low-altitude orbits circle the Earth 16 times a day. 08:08: They quickly smear out in a ring around the Earth, making tracking and avoidance that much more difficult. 06:03: Satellites in low earth orbit may need to be boosted a few times a year to prevent this inspiral. 11:21: The Kessler syndrome accelerates, churning up low earth orbit into a cloud of shrapnel. 11:54: Higher orbits, like medium earth orbit where the GPS satellites live, will probably also be okay due to the relative low density up there. 12:02: ... to high altitudes- maybe they could be destroyed in collisions in low earth orbit, creating a train of debris that wreaks havoc higher ... 12:13: But the real risk is for anything trying to stay in low earth orbit. 12:42: After about a decade, very low earth orbit - up to 400km - will become usable again. 12:02: ... to high altitudes- maybe they could be destroyed in collisions in low earth orbit, creating a train of debris that wreaks havoc higher ... 04:17: Below around 1000 km, Earth’s atmosphere is incredibly diffuse but still present. 05:41: I already mentioned that orbits decay due to interaction with the upper reaches of Earth’s atmosphere. 12:59: ... trash to fall faster, or even electromagnetic tethers which push on earth’s magnetic field to deorbit a ... 13:14: ... to maintain our cosmic front yard, and continue our safe use of Earth’s orbital space ... 04:17: Below around 1000 km, Earth’s atmosphere is incredibly diffuse but still present. 05:41: I already mentioned that orbits decay due to interaction with the upper reaches of Earth’s atmosphere. 12:59: ... trash to fall faster, or even electromagnetic tethers which push on earth’s magnetic field to deorbit a ... 13:14: ... to maintain our cosmic front yard, and continue our safe use of Earth’s orbital space ...
	2021-05-25: What If (Tiny) Black Holes Are Everywhere? 10:37: Let’s get a bit more down to earth before we wrap up.
	2021-05-19: Breaking The Heisenberg Uncertainty Principle 05:10: Those ripples are tiny by the time they reach Earth - they change lengths by something like 1 part in a billion trillion in the most powerful cases.
	2021-05-11: How To Know If It's Aliens 00:19: 45 years ago, a pair of small Earth spacecraft inserted themselves into orbit around Mars. 01:55: ... additional shots of nutrients were injected. Now when this is done with Earth samples, new bursts of gas are always observed as the microbes wake up ... 04:11: ... also difficult to rule out contamination by Earth microbes - after all, the thing had been buried in Antarctica for ... 05:11: ... Array. Phosphine is a common byproduct of biological activity on Earth, but it was difficult to come up with a non-living source of so much of ... 06:27: ... Well the answer is simple: because there are more things in heaven and earth than are dreamt of in your ... 04:11: ... also difficult to rule out contamination by Earth microbes - after all, the thing had been buried in Antarctica for millions of ... 01:55: ... additional shots of nutrients were injected. Now when this is done with Earth samples, new bursts of gas are always observed as the microbes wake up and start ... 00:19: 45 years ago, a pair of small Earth spacecraft inserted themselves into orbit around Mars. 11:24: ... was also recently shown to have a planetary system, including a nearly Earth-mass planet it its habitable zone, where liquid water is possible. Now the ...
	2021-04-07: Why the Muon g-2 Results Are So Exciting! 03:15: ... an electric charge around a looped wire, or have electrical currency in Earth's spinning ...
	2021-03-23: Zeno's Paradox & The Quantum Zeno Effect 15:48: So then the amplitude of the wave as we see it at Earth tells us how much distance the wave must have traveled.
	2021-03-16: The NEW Crisis in Cosmology 07:28: ... can use this same trick to measure the distance to stars. As the earth orbits the   sun over the course of the year, nearby ... 08:03: ... we put telescopes in space - above   the blurring effect of Earth’s atmosphere it’s possible to make better position ... 07:28: ... can use this same trick to measure the distance to stars. As the earth orbits the   sun over the course of the year, nearby ... 08:03: ... we put telescopes in space - above   the blurring effect of Earth’s atmosphere it’s possible to make better position ...
	2021-03-09: How Does Gravity Affect Light? 10:09: Okay, imagine you’re looking at the earth from a distance. 10:12: A photon passes by, and the amount of time it takes to cross that space is larger than if Earth wasn’t there.
	2021-02-24: Does Time Cause Gravity? 02:27: OK, now let’s add a second object - something nice and massive … the planet Earth will do. 02:42: Things closer to the Earth move through time more slowly. 02:51: Clocks closer to the Earth take longer to tick for every tick on a distant clock. 02:55: Velocity through time increases away from the Earth. 02:58: ... sense of time flowing in a gradient - faster streams distant from the Earth, slower streams near ... 03:16: It’s almost like Earth’s mass creates a drag on the flow of time around it. 03:22: So what happens to an object sitting in this stream of time - parts further away from the Earth age faster, right? 02:58: ... sense of time flowing in a gradient - faster streams distant from the Earth, slower streams near ... 03:16: It’s almost like Earth’s mass creates a drag on the flow of time around it.
	2021-02-17: Gravitational Wave Background Discovered? 00:00: ... black holes and neutron stars across the universe these sweep past the earth every few days causing space itself to oscillate lengths and widths ...
	2021-02-10: How Does Gravity Warp the Flow of Time? 01:00: ... the sense of weight you feel stationary on the surface of the Earth is identical to the sense of weight you would feel accelerating at 1-g ... 07:36: We can see that when we use a spacetime diagram to show how the traveler tracks the passage of time back on Earth. 10:08: Well, as deep as the distance back to Earth - which is why the time dilation in this case is so huge, even if the acceleration is mild.
	2021-01-26: Is Dark Matter Made of Particles? 06:17: ... out there in the universe or in our particle experiments here on Earth for evidence of particles that don’t fit the standard ... 12:47: ... to let you know that while we love talking about Space, if you have more Earthly concerns, you should check out PBS Terra on YouTube, and their show ...
	2021-01-19: Can We Break the Universe? 01:04: Say we have a spaceship traveling from Earth to a nearby star at a good fraction of the speed of light. 01:09: ... more slowly from the point of view of a stationary observer back on the Earth. ... 01:28: The spaceship can think of itself as stationary - it perceives the Earth as racing away from it and its destination star racing towards it. 01:35: That means it sees clocks back on the Earth ticking more slowly, and the Earth and the distance traveled being squished. 01:42: ... become paradoxes if the different observers - on the spaceship and on Earth - can compare the results of an experiment and get unresolvable ... 01:52: ... there IS a disagreement between the astronaut and an observer back on Earth about the relative passage of time and the distance traveled - but those ... 02:08: ... observer on Earth thinks the astronaut’s clock ticked slow, but the astronaut thinks they ... 03:24: ... speed of light to a nearby star and then turns around and heads back to Earth. ... 03:31: According to the twin back on Earth, his sister’s clock has been ticking slower than his own. 03:36: But according to the traveling twin, Earth appears to have raced away and then raced back again. 03:57: ... two separate moving frames - one moving away and one moving towards the Earth. ... 04:15: Let’s say we’re in Earth’s reference frame so the Earth doesn’t move in space - just straight up, which means forward in time. 04:22: The spaceship moves in both space and time - first away from the earth and then back towards it. 04:57: ... because they allow us to track the apparent passage of time back on Earth from the point of view of the ... 05:07: She counts every time a new years day happens on Earth according to her calculations. 05:12: ... one of these lines of constant time extending from January 1st on earth crosses the spaceship’s path - its ... 05:28: In total, the traveler counts fewer Earth years because she misses some time in the middle corresponding to the turn-around point. 05:36: Those years do happen back on earth, but they don’t correspond to any time point that happens to the astronaut. 05:56: In that case, the traveling twin would not need to turn around in order to get back to Earth to compare ages. 01:42: ... become paradoxes if the different observers - on the spaceship and on Earth - can compare the results of an experiment and get unresolvable ... 03:36: But according to the traveling twin, Earth appears to have raced away and then raced back again. 05:12: ... one of these lines of constant time extending from January 1st on earth crosses the spaceship’s path - its ... 04:15: Let’s say we’re in Earth’s reference frame so the Earth doesn’t move in space - just straight up, which means forward in time. 02:08: ... observer on Earth thinks the astronaut’s clock ticked slow, but the astronaut thinks they ... 01:35: That means it sees clocks back on the Earth ticking more slowly, and the Earth and the distance traveled being squished. 05:28: In total, the traveler counts fewer Earth years because she misses some time in the middle corresponding to the turn-around point. 06:32: The earth-bound twin moves straight up as usual, but the traveling twin now does a single loop of a helix to intercept her brother’s upward path. 04:15: Let’s say we’re in Earth’s reference frame so the Earth doesn’t move in space - just straight up, which means forward in time.
	2021-01-12: What Happens During a Quantum Jump? 03:40: ... of epicycles—the long dead theory about the motion of the planets in an Earth-centered solar ...
	2020-12-22: Navigating with Quantum Entanglement 02:22: ... proposal that birds have a “magnetoreception” that they navigate by the Earth’s magnetic field came from the Russian zoologist Alexander von Middendorf ... 03:03: ... interesting one: the idea that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 03:31: This “geomagnetic” field is generated by the convective motion in Earth’s outer core - which is a churning liquid mass of white-hot nickel and iron. 03:55: At any point on the surface of the earth, our geomagnetic field can be described with just a few properties. 04:12: This “declination” points towards the magnetic poles, which are offset from the true poles defined by Earth’s rotational axis. 04:32: At Earth’s surface it’s about 30 microTesla, which is about 100 times weaker than a fridge magnet. 05:23: ... you need a lot of electrons to register Earth’s extremely weak field - far more than you could fit into the microscopic ... 07:10: ... spin tends to stay fixed until disturbed by its environment. And Earth's magnetic field isn't strong enough to influence spin in that ... 07:35: But even a weak magnetic field like the Earth's can affect the amount of time the radical pair spends in these states. 07:53: ... how long does the entanglement need to last in order to be influenced by Earth's magnetic field, and how does the simple slipping of electron spins go on ... 08:43: ... modified if the bird changes the orientation of its head relative to the Earth’s magnetic ... 10:40: ... states - their spin state wouldn’t be sensitive enough to detect Earth’s ... 15:10: ... is a hypothetical piece of chinaware that orbits the sun between the earth and mars, and which science has yet to prove doesn’t ... 02:22: ... proposal that birds have a “magnetoreception” that they navigate by the Earth’s magnetic field came from the Russian zoologist Alexander von Middendorf ... 03:03: ... interesting one: the idea that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 03:31: This “geomagnetic” field is generated by the convective motion in Earth’s outer core - which is a churning liquid mass of white-hot nickel and iron. 04:12: This “declination” points towards the magnetic poles, which are offset from the true poles defined by Earth’s rotational axis. 04:32: At Earth’s surface it’s about 30 microTesla, which is about 100 times weaker than a fridge magnet. 05:23: ... you need a lot of electrons to register Earth’s extremely weak field - far more than you could fit into the microscopic ... 07:10: ... spin tends to stay fixed until disturbed by its environment. And Earth's magnetic field isn't strong enough to influence spin in that ... 07:35: But even a weak magnetic field like the Earth's can affect the amount of time the radical pair spends in these states. 07:53: ... how long does the entanglement need to last in order to be influenced by Earth's magnetic field, and how does the simple slipping of electron spins go on ... 08:43: ... modified if the bird changes the orientation of its head relative to the Earth’s magnetic ... 10:40: ... states - their spin state wouldn’t be sensitive enough to detect Earth’s ... 05:23: ... you need a lot of electrons to register Earth’s extremely weak field - far more than you could fit into the microscopic structures ... 10:40: ... states - their spin state wouldn’t be sensitive enough to detect Earth’s field. ... 02:22: ... proposal that birds have a “magnetoreception” that they navigate by the Earth’s magnetic field came from the Russian zoologist Alexander von Middendorf back in ... 03:03: ... interesting one: the idea that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 07:10: ... spin tends to stay fixed until disturbed by its environment. And Earth's magnetic field isn't strong enough to influence spin in that ... 07:53: ... how long does the entanglement need to last in order to be influenced by Earth's magnetic field, and how does the simple slipping of electron spins go on to give ... 08:43: ... modified if the bird changes the orientation of its head relative to the Earth’s magnetic ... 02:22: ... proposal that birds have a “magnetoreception” that they navigate by the Earth’s magnetic field came from the Russian zoologist Alexander von Middendorf back in ... 03:03: ... interesting one: the idea that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 07:10: ... spin tends to stay fixed until disturbed by its environment. And Earth's magnetic field isn't strong enough to influence spin in that ... 07:53: ... how long does the entanglement need to last in order to be influenced by Earth's magnetic field, and how does the simple slipping of electron spins go on to give the ... 08:43: ... modified if the bird changes the orientation of its head relative to the Earth’s magnetic field. ... 03:31: This “geomagnetic” field is generated by the convective motion in Earth’s outer core - which is a churning liquid mass of white-hot nickel and iron. 04:12: This “declination” points towards the magnetic poles, which are offset from the true poles defined by Earth’s rotational axis. 04:32: At Earth’s surface it’s about 30 microTesla, which is about 100 times weaker than a fridge magnet.
	2020-12-15: The Supernova At The End of Time 00:10: ... say “ends” plural, because many very final-seeming fates await the Earth, then solar system, then galaxy, and ultimately the ...
	2020-12-08: Why Do You Remember The Past But Not The Future? 02:40: ... it formed billions of years ago, before even Earth formed, when tiny particles of dust from a past supernova found each ...
	2020-10-27: How The Penrose Singularity Theorem Predicts The End of Space Time 08:11: ... try an analogy - the geodesics we  use to map the surface of the earth are   longitude and latitude. Lines of longitude  come to ...
	2020-10-13: Do the Past and Future Exist? 13:36: ... points out that any Venusian life that we find is very likely from Earth - having transported to Venus on rocks that were blasted from Earth's ... 13:44: And Afto Kinito points out that it could easily have happened in the other direction - Earth life being seeded by Venusian meteorites. 13:53: ... Earth and Venus do exchange a lot of material, so it's almost certain that ... 13:36: ... points out that any Venusian life that we find is very likely from Earth - having transported to Venus on rocks that were blasted from Earth's ... 13:44: And Afto Kinito points out that it could easily have happened in the other direction - Earth life being seeded by Venusian meteorites. 13:36: ... from Earth - having transported to Venus on rocks that were blasted from Earth's surface by ...
	2020-10-05: Venus May Have Life! 00:23: ... searches for life-beyond Earth have tended to focus on the Martian subsurface and the ocean moons ... 01:05: It’s bright because it’s close and it’s big, at 90% Earth’s diameter, and its our closest planetary neighbor. 01:12: In many ways it’s Earth’s twin - it’s even inside that band around the Sun where liquid water is possible - the so-called habitable zone. 01:28: Its atmosphere is 100 times the mass of Earth’s and mostly carbon dioxide. 02:43: ... 50km altitude both the temperature and pressure are close to those at Earth’s surface, with the only problem being that pesky sulphuric acid ... 08:49: ... comparison, the most extreme extremophiles on Earth can survive in pools with something like 5% concentration of sulphuric ... 09:00: So these Venutian microbes would have to be very different to anything found on Earth. 09:36: Earth bacteria can transform into dormant states in adverse conditions - bacterial spores. 11:44: But ultimately we’re going to want to go to Venus, to search for life signatures there or, even better, to bring samples back to Earth. 09:36: Earth bacteria can transform into dormant states in adverse conditions - bacterial spores. 01:05: It’s bright because it’s close and it’s big, at 90% Earth’s diameter, and its our closest planetary neighbor. 01:12: In many ways it’s Earth’s twin - it’s even inside that band around the Sun where liquid water is possible - the so-called habitable zone. 01:28: Its atmosphere is 100 times the mass of Earth’s and mostly carbon dioxide. 02:43: ... 50km altitude both the temperature and pressure are close to those at Earth’s surface, with the only problem being that pesky sulphuric acid ... 01:05: It’s bright because it’s close and it’s big, at 90% Earth’s diameter, and its our closest planetary neighbor. 02:43: ... 50km altitude both the temperature and pressure are close to those at Earth’s surface, with the only problem being that pesky sulphuric acid ... 01:12: In many ways it’s Earth’s twin - it’s even inside that band around the Sun where liquid water is possible - the so-called habitable zone.
	2020-09-21: Could Life Evolve Inside Stars? 08:35: For example, life uses the energy flowing from the high energy-density of the Sun to the lower energy density of the Earth. 11:28: ... is a higher being composed of cosmic strings and monopoles, visiting Earth from the core of the Sun to help spread cosmic ... 14:30: ... why Ptolemy was able to make this Earth-centered model sort of work - with enough epicycles he could have created a ...
	2020-09-08: The Truth About Beauty in Physics 01:12: ... the first effort, by Claudius Ptolemy, the planets orbited the Earth in complicated systems of circles embedded within circles - what we call ... 01:26: Nicholaus Copernicus found more beauty of simplicity by placing the Earth along with all planets in simple circular orbits around the Sun.
	2020-09-01: How Do We Know What Stars Are Made Of? 00:10: Or lights kindled above middle earth by Varda Elbereth and brightened with the dew of the trees of Valinor? 05:32: ... lines corresponded to the most common elements on the surface of the Earth. ... 05:41: The prevailing wisdom came to be that the sun was made of exactly the same stuff as the Earth - just a lot, lot hotter. 08:43: ... they varied between stars, but were generally similar to what we find on Earth’s surface - but with a couple of extreme ... 08:56: On Earth, hydrogen is the third most abundant element after oxygen and silicon, while helium is extremely rare. 09:18: This was totally against the current scientific consensus - which was that the Sun was made of the same stuff as the Earth. 05:41: The prevailing wisdom came to be that the sun was made of exactly the same stuff as the Earth - just a lot, lot hotter. 08:56: On Earth, hydrogen is the third most abundant element after oxygen and silicon, while helium is extremely rare. 08:43: ... they varied between stars, but were generally similar to what we find on Earth’s surface - but with a couple of extreme ...
	2020-08-24: Can Future Colliders Break the Standard Model? 07:25: ... or quasars or galactic magnetic fields, which continuously spray the earth with particles at higher energies than we can hope to ...
	2020-08-17: How Stars Destroy Each Other 01:31: Centuries later, on March 11, 1437, the light from that explosion swept past the Earth. 06:16: ... a jet that traces a circle across the sky - and often sweeping past the earth to produce metronome-precise pulses - most brightly in radio light, but ... 10:25: As you know, at the start of the pandemic we all had to quarantine on Earth to avoid contaminating space with the virus. 10:32: ... we finally managed to develop protocols to protect the universe from Earthly lurgies and so here I am, floating in the void once ...
	2020-07-28: What is a Theory of Everything: Livestream 00:00: ... doesn't fall down what if in fact the laws of gravity that work on earth also apply up in the sky and boom they did work but even at that time ...
	2020-07-20: The Boundary Between Black Holes & Neutron Stars 02:30: ... in close succession, consistent with a wave traveling through the entire earth at the speed of ... 05:20: That insane density gives the neutron star a surface gravity around 100 billion times stronger than the surface of the Earth. 06:52: In the case of the earth the phantom event horizon is about a centimeter in diameter. 08:43: ... that result from a neutron star’s precessing jets sweeping past the earth. ...
	2020-07-08: Does Antimatter Explain Why There's Something Rather Than Nothing? 10:56: ... time. The CPT theorem states that the acceleration of an anti-atom in Earth’s gravitational field should be exactly the same as for an atom, but ...
	2020-06-15: What Happens After the Universe Ends? 15:40: Drakenkorin27, who is a bona fide virologist, gave us even more reason to doubt that any viruses from space have ever infected earth life. 15:54: ... points out that the DNA of all life that evolved on earth uses the same code for instructing the molecular machinery to translate ... 16:27: MC’s creates notes that if the RNA world hypothesis is correct, then viruses were the first "life" to appear on Earth. 16:56: Devin Smith asks what protocols exist for protecting earth from alien microbes, should they be discovered on a mission - say, to Mars. 15:40: Drakenkorin27, who is a bona fide virologist, gave us even more reason to doubt that any viruses from space have ever infected earth life.
	2020-06-08: Can Viruses Travel Between Planets? 00:33: There are far more viruses on Earth than all cellular organisms combined, and so they drastically affect our entire biosphere. 00:50: That’s right, viruses or their ancestors may have played a role in the origin of life on earth, and may be needed to initiate life on any planet. 01:13: The new coronavirus - Sars-CoV-2, the virus that causes COVID-19 did absolutely not fall to earth from space. 04:19: ... extreme abundance of viruses on Earth, and their critical role in evolution and possibly even abiogenesis, ... 05:12: But what about finding viruses in rocks that fall to Earth? 07:12: Earth’s upper atmosphere is thick with bacteria and viruses - mostly swept into the atmosphere from the oceans by seaspray. 08:13: This is lithopanspermia, and again - virus-ridden rocks have definitely left the Earth before, and probably impacted other bodies in our solar system. 08:24: Earth certainly gets hit by rocks from Mars - so if Mars ever had viruses then some of that material may have reached Earth. 11:04: OK, so we’ve established that there’s at least a remote chance of interplanetary or interstellar viruses making their way to Earth. 11:13: Or Earth viruses going back the other way. 11:43: At the very minimum, a cell needs to be DNA or RNA-based to be susceptible to earth viruses. 12:14: But it’s very likely that an alien virus that made its way to earth would find it had absolutely no way to attack the cells it finds here. 11:13: Or Earth viruses going back the other way. 11:43: At the very minimum, a cell needs to be DNA or RNA-based to be susceptible to earth viruses. 12:59: It’s never aliens if there’s a sensible earthly explanation. 07:12: Earth’s upper atmosphere is thick with bacteria and viruses - mostly swept into the atmosphere from the oceans by seaspray.
	2020-05-27: Does Gravity Require Extra Dimensions? 09:24: ... 10 million times smaller than the force the lead balls felt due to the earth ...
	2020-05-18: Mapping the Multiverse 02:40: The event horizon itself is distorted - wider at the equator than the poles, just like the rotating earth.
	2020-05-11: How Luminiferous Aether Led to Relativity 01:34: ... was embodied as a primordial deity of light. In Aristotle’s cosmology, earth, air, fire and water are the physical elements of the world, while aether ... 08:02: ... why build a fast-moving lab when you already have a fast-moving planet? Earth hurtles around the Sun at 30 km/s - that’s only one one hundredth of one ... 10:02: ... mercury so it would maintain a fixed orientation despite the earth rotating beneath ... 10:42: ... budge. OK, so maybe the aether happens to be moving exactly with the earth - fine, try it 6 months later when the earth is moving in the opposite ... 01:34: ... was embodied as a primordial deity of light. In Aristotle’s cosmology, earth, air, fire and water are the physical elements of the world, while aether is ... 08:02: ... why build a fast-moving lab when you already have a fast-moving planet? Earth hurtles around the Sun at 30 km/s - that’s only one one hundredth of one percent ... 10:02: ... mercury so it would maintain a fixed orientation despite the earth rotating beneath ...
	2020-05-04: How We Know The Universe is Ancient 00:17: ... for assuming that the universe above is fixed and unchanging. But the Earth was also thought to be timeless - until we learned to see billions of ... 07:07: ... didn’t sound right. By then, geologists had already found rocks here on earth that were at least 3 billion years old! So there was a problem - but it ... 08:17: ... must be 3.6 billion years old. At last, the universe was older than the earth – although still a way off our modern ... 00:17: ... In our recent episode we learned how we calculate the age of the Earth based on radioactive decay in its most ancient ...
	2020-04-14: Was the Milky Way a Quasar? 00:38: Whatever is happening here on Earth, the universe remains awesome. 12:09: ... over any extra gamma rays being generated by this process, because our Earth’s atmosphere absorbs most of the gamma ray radiation that comes our ... 13:27: It’s a journey to Earth’s most remote laboratories to see how science is done in Antartica. 13:39: And speaking of Terra, last week we delved into the science and non-science of how we determine the age of the earth. 13:48: ... use uranium-lead dating with zircon crystals to calculate the age of the Earth. ... 14:01: ... Clair – who was not only the first to get the right age for the earth, significantly advance this radiometric dating technique, but he also ... 15:01: A number of you quoted Good Omens, which itself has a very precise claim for the age of the Earth. 15:24: By the same token the earth itself is generally supposed to be about four and a half thousand million years old. 15:48: ... et Novi Testamenti in 1654, which suggested that the Heaven and the Earth were created in 4004 ... 15:59: ... the calculation further, and was able to announce triumphantly that the Earth was created on Sunday the 21th of October, 4004 B.C., at exactly 9:00 ... 16:19: By almost a quarter of an hour." Tasha Montgomery points out that this makes Earth a Libra. Seriously Tasha Have you learned nothing on this show. 16:35: So accounting for our axil procession, I think that makes Earth a Taurus, which really explains so much. 12:09: ... over any extra gamma rays being generated by this process, because our Earth’s atmosphere absorbs most of the gamma ray radiation that comes our ... 13:27: It’s a journey to Earth’s most remote laboratories to see how science is done in Antartica. 12:09: ... over any extra gamma rays being generated by this process, because our Earth’s atmosphere absorbs most of the gamma ray radiation that comes our ...
	2020-04-07: How We Know The Earth Is Ancient 00:00: ... our universe. And it came as scientists tried to measure the age of the Earth. What they found was as shocking and humbling as anything ever seen ... 01:48: ... Comte de Buffon, was among the first to calculate the age of the Earth using what we would now call scientific methods, publishing his result ... 02:38: ... that they were formed when molten rock pus hed through the crust from Earth’s ... 03:08: ... But those processes were excruciatingly slow, and so Hutton realised the Earth must be unthinkably ... 03:30: ... can thank Hutton and his 1788 book the Theory of the Earth for opening scientific eyes to the possibility of an ancient planet, and ... 03:43: ... far into the abyss of time.” Hutton didn’t propose a beginning for the Earth - instead he assumed an infinite series of cycles. This was also the ... 04:32: ... time and deep space. We’d known since Copernicus and Galileo that earth was just one planet among several in our solar system. Astronomers now ... 05:50: ... his Origin of Species, he estimated a minimum age of the earth based on the erosion timescale for chalk formations in Southern England. ... 06:47: ... that radioactive decay is responsible for keeping the interior of the Earth hot - and explains why Earth is much older than Buffon’s 75,000 year ... 07:17: ... gave us our most accurate way to figure out the age of chunks of the Earth through radiometric dating. Unstable atomic nuclei decay into lighter ... 08:25: ... and so much more abundant. Carbon-14 exists on the surface of the earth because it’s produced when cosmic rays hit nitrogen in the atmosphere, ... 09:13: ... useful for measuring the age of the earth is uranium-lead dating. Uranium decays on much longer timescales - 710 ... 10:35: ... the 1920s, British geologist Arthur Holmes would declare that the Earth was between 1.6 to 3.0 billion years old, based on his radiometric ... 11:02: ... rocks were discovered, pushing back Earth’s age further and further. But beyond a few billion years it starts to get ... 12:07: ... day of Brahma is 4.32 billion years. Oddly close to the age of the Earth - although it looks like we survived one day of Brahma AND the last ... 12:35: ... to the stratified depths of the Grand Canyon. Not that our ancient Earth cares - it’s revolved around the sun 4.5 billion times through deep ... 03:43: ... far into the abyss of time.” Hutton didn’t propose a beginning for the Earth - instead he assumed an infinite series of cycles. This was also the ... 11:02: ... the Earth. We believe that the moon formed at the same time as the Earth - both coallescing after a giant planetary impact in the early solar ... 12:07: ... day of Brahma is 4.32 billion years. Oddly close to the age of the Earth - although it looks like we survived one day of Brahma AND the last ... 05:50: ... his Origin of Species, he estimated a minimum age of the earth based on the erosion timescale for chalk formations in Southern England. His ... 12:35: ... to the stratified depths of the Grand Canyon. Not that our ancient Earth cares - it’s revolved around the sun 4.5 billion times through deep space and ... 06:47: ... that radioactive decay is responsible for keeping the interior of the Earth hot - and explains why Earth is much older than Buffon’s 75,000 year ... 01:48: ... publishing his result in 1778. It was ingenious really. He assumed the Earth started as a ball of molten rock, which subsequently cooled down to its current ... 02:38: ... that they were formed when molten rock pus hed through the crust from Earth’s ... 11:02: ... rocks were discovered, pushing back Earth’s age further and further. But beyond a few billion years it starts to get ... 02:38: ... that they were formed when molten rock pus hed through the crust from Earth’s interior. ...
	2020-03-31: What’s On The Other Side Of A Black Hole? 00:37: ... grid up the surface of the Earth in lines of longitude and latitude so that every point on the planet can ... 02:56: ... horizon. The event horizon is just a coordinate singularity like the earth’s poles, and to make a smooth map through it we need a Mercator projection ...
	2020-03-24: How Black Holes Spin Space Time 05:14: ... in the direction of the object’s spin. Gravity Probe B measured the Earth’s frame dragging and it was exactly as Einstein’s theory predicted - ... 08:37: ... case is not spherical - it’s squished at the poles, like the rotating Earth. More spin equals more squished. The ergosphere has a similar shape - but ... 05:14: ... in the direction of the object’s spin. Gravity Probe B measured the Earth’s frame dragging and it was exactly as Einstein’s theory predicted - ...
	2020-03-03: Does Quantum Immortality Save Schrödinger's Cat? 11:24: Antarctic Extremes is about exploring how science is done in some of the harshest conditions on Earth.
	2020-02-03: Are there Infinite Versions of You? 03:45: ... our part of the universe, leading to the formation of the Milky Way, the Earth, William Shakespeare, and ...
	2020-01-20: Solving the Three Body Problem 04:29: ... It works very well for tiny things like artificial satellites around the Earth. It can also be used to approximate the orbits of the moon relative to ... 05:01: ... a three-body system with no analytic solution, before we even add in the Earth. ... 06:43: ... any of these 5 orbits and it will stay there indefinitely, tracking the Earth’s orbit around the Sun. We now call these the Lagrange points, and they’re ... 04:29: ... approximate the orbits of the moon relative to the Earth and Sun, or the Earth relative to the Sun and ... 06:43: ... any of these 5 orbits and it will stay there indefinitely, tracking the Earth’s orbit around the Sun. We now call these the Lagrange points, and they’re ...
	2020-01-13: How To Capture Black Holes 04:50: ... - much like how a satellite’s orbit will decay if it’s too close to Earth’s ... 09:53: ... radiation - and those flashes may be visible to telescopes on Earth right after the gravitational waves ... 04:50: ... - much like how a satellite’s orbit will decay if it’s too close to Earth’s ...
	2020-01-06: How To Detect a Neutrino 07:04: ... do is we're going to send a super intense beam of neutrinos through the Earth ♪ ♪ 1,300 kilometers from Chicago to South Dakota, where ♪ ♪ a huge ...
	2019-12-09: The Doomsday Argument 06:26: ... the second scenario, humanity never leaves the Earth and only manages to survive to produce about the same number of people ...
	2019-12-02: Is The Universe Finite? 04:56: ... slightly positive or very slightly negative - just as the surface of the Earth appears flat if you’re standing on the ...
	2019-11-18: Can You Observe a Typical Universe? 00:34: ... Copernicus presented his model of the solar system which demoted the Earth from its position at the center of the universe into just one of several ... 01:11: It’s extremely important - it allows us to study the distant universe confident that its laws of physics are the same as we experience on Earth. 01:20: It allows us to understand the origin of the Earth and the Milky Way by studying the ancient light of distant galaxies. 01:45: Earth certainly isn’t central, but it IS privileged, and not at all a typical environment. 04:04: And we shouldn’t be surprised that we find ourselves in one, even though Earth and a life supporting universe might be quite atypical. 13:39: ... the multi-verse and unleash a Star Trek-esque science utopia here on Earth. ...
	2019-11-11: Does Life Need a Multiverse to Exist? 13:09: ... the last episode we discussed the Rare Earth Hypothesis - the idea that planets supporting intelligent life may be ... 13:23: Of course some of you mentioned some "rare earth" qualities that we didn't get to. 13:28: ... due to a giant impact would also have increased the amount of iron in Earth's core, which may help explain the strength of our protective magnetic ... 13:40: ... scenario is that some mars-sized planet plowed into early earth, causing a lot of Earth's rocky crust to be thrown into orbit before ... 13:50: Meanwhile, Earth's iron core would have grown as it absorved the iron core of the smaller planet. 14:34: ... Williams disagrees with a lot of these 'rare earth' type scenarios because the factors we talk about are needed for OUR ... 14:52: ... counterpoint is that, although we don't know if any one rare quality of Earth is absolutely necessary for life, there do seem to be quite a lot of ... 16:59: Actually these just came in while I was writing the rare earth episode, as soon as I started thinking about how we're totally screwing it all up. 13:40: ... scenario is that some mars-sized planet plowed into early earth, causing a lot of Earth's rocky crust to be thrown into orbit before congealing ... 16:59: Actually these just came in while I was writing the rare earth episode, as soon as I started thinking about how we're totally screwing it all up. 13:09: ... the last episode we discussed the Rare Earth Hypothesis - the idea that planets supporting intelligent life may be extremely ... 13:23: Of course some of you mentioned some "rare earth" qualities that we didn't get to. 14:34: ... Williams disagrees with a lot of these 'rare earth' type scenarios because the factors we talk about are needed for OUR ... 13:28: ... due to a giant impact would also have increased the amount of iron in Earth's core, which may help explain the strength of our protective magnetic ... 13:40: ... is that some mars-sized planet plowed into early earth, causing a lot of Earth's rocky crust to be thrown into orbit before congealing into the ... 13:50: Meanwhile, Earth's iron core would have grown as it absorved the iron core of the smaller planet. 13:28: ... due to a giant impact would also have increased the amount of iron in Earth's core, which may help explain the strength of our protective magnetic ... 13:50: Meanwhile, Earth's iron core would have grown as it absorved the iron core of the smaller planet. 13:40: ... is that some mars-sized planet plowed into early earth, causing a lot of Earth's rocky crust to be thrown into orbit before congealing into the ...
	2019-11-04: Why We Might Be Alone in the Universe 00:12: Actually, it turns out that our very privileged perspective on the universe from Earth’s comfortable biosphere may tell us a lot about our reality. 02:40: ... rare earth hypothesis posits exactly this - that a range of factors made Earth ... 03:22: ... civilizations are exceedingly rare - and maybe that’s because Earth is an exceedingly rare ... 03:58: ... the Rare Earth hypothesis is a little more optimistic - it states that planets capable ... 04:14: It highlights a series of remarkable qualities of planet Earth that may have been needed for life and intelligence to arise here. 04:23: Actually, let’s start by something that is NOT rare about the Earth. 04:31: ... by Earth-like I mean rocky planets about the size of the Earth in orbit around stars very similar to the Sun at the right distance to ... 05:12: Unless Earth has special qualities that mean true Earth-like planets are much rarer. 05:16: Let’s think about what Earth’s has got that seems critical for life and that could be unique. 05:28: ... if we’ve only ever seen that quality on Earth then it could be hugely uncommon - and the weak anthropic principle says ... 05:48: ... Earth has two qualities not shared by the other rocky planets in our solar ... 05:59: ... Earth’s solid iron inner core spins suspended in a molten metal outer core, and ... 06:11: Above Earth’s core is a solid mantle which still flows due to its heat. 06:16: This drives plate tectonics on the surface - plates of Earth’s crust float around and are periodic drawn back into the mantle, or subducted. 06:51: So Earth’s dynamic interior seems to be life-critical in multiple ways. 07:12: Earth’s moon is ridiculously gigantic - no other rocky planet in our system has anything like it. 07:19: Its size and also its composition and orbit suggest that it formed when a Mars-ish sized planet collided with the Earth right after its formation. 07:43: That impact likely gave Earth its rapid rotation rate - with short nights essential for photosynthesis, and also its axial tilt. 08:02: Earth’s tilt seems just right - perhaps even rare. 08:06: That impact may even have kickstarted Earth’s extreme tectonic activity by fragmenting Earth’s early crust into moving plates. 08:59: OK, so Earth is weirdly dynamic and has a weirdly giant moon, but there’s more. 09:48: It no doubt sucked up many comets and asteroids would otherwise have hit the Earth. 10:04: ... are a few other possible rare Earth factors - we may have an unusually hospitable atmosphere and water ... 10:17: But the final thing that may make Earth a cosmic rarity is the path taken by evolution. 11:08: ... are many factors that shaped Earth’s formation and development - what if the Cambrian explosion had never ... 11:20: There are lots of ways that it seems Earth got lucky. 11:24: The question raised by the rare earth hypothesis is just how lucky were we? 11:29: ... of Earth’s life-critical qualities or development steps have not been seen ... 12:11: We find ourselves in the only place we could be: gazing out from our rare earth into the untamed, unpopulated reaches of spacetime. 02:40: ... rare earth hypothesis posits exactly this - that a range of factors made Earth exceptionally unusual and uniquely able to produce intelligent ... 10:04: ... are a few other possible rare Earth factors - we may have an unusually hospitable atmosphere and water content and ... 02:40: ... rare earth hypothesis posits exactly this - that a range of factors made Earth exceptionally ... 03:58: ... the Rare Earth hypothesis is a little more optimistic - it states that planets capable of spawning ... 11:24: The question raised by the rare earth hypothesis is just how lucky were we? 02:40: ... rare earth hypothesis posits exactly this - that a range of factors made Earth exceptionally unusual ... 04:29: Earth-like planets are common. 04:31: ... by Earth-like I mean rocky planets about the size of the Earth in orbit around stars ... 05:12: Unless Earth has special qualities that mean true Earth-like planets are much rarer. 04:29: Earth-like planets are common. 04:31: ... by Earth-like I mean rocky planets about the size of the Earth in orbit around stars ... 05:12: Unless Earth has special qualities that mean true Earth-like planets are much rarer. 04:29: Earth-like planets are common. 05:12: Unless Earth has special qualities that mean true Earth-like planets are much rarer. 00:12: Actually, it turns out that our very privileged perspective on the universe from Earth’s comfortable biosphere may tell us a lot about our reality. 05:16: Let’s think about what Earth’s has got that seems critical for life and that could be unique. 05:59: ... Earth’s solid iron inner core spins suspended in a molten metal outer core, and ... 06:11: Above Earth’s core is a solid mantle which still flows due to its heat. 06:16: This drives plate tectonics on the surface - plates of Earth’s crust float around and are periodic drawn back into the mantle, or subducted. 06:51: So Earth’s dynamic interior seems to be life-critical in multiple ways. 07:12: Earth’s moon is ridiculously gigantic - no other rocky planet in our system has anything like it. 08:02: Earth’s tilt seems just right - perhaps even rare. 08:06: That impact may even have kickstarted Earth’s extreme tectonic activity by fragmenting Earth’s early crust into moving plates. 11:08: ... are many factors that shaped Earth’s formation and development - what if the Cambrian explosion had never ... 11:29: ... of Earth’s life-critical qualities or development steps have not been seen ... 00:12: Actually, it turns out that our very privileged perspective on the universe from Earth’s comfortable biosphere may tell us a lot about our reality. 06:11: Above Earth’s core is a solid mantle which still flows due to its heat. 06:16: This drives plate tectonics on the surface - plates of Earth’s crust float around and are periodic drawn back into the mantle, or subducted. 06:51: So Earth’s dynamic interior seems to be life-critical in multiple ways. 08:06: That impact may even have kickstarted Earth’s extreme tectonic activity by fragmenting Earth’s early crust into moving plates. 11:08: ... are many factors that shaped Earth’s formation and development - what if the Cambrian explosion had never happened, or ... 11:29: ... of Earth’s life-critical qualities or development steps have not been seen elsewhere, nor do they ... 07:12: Earth’s moon is ridiculously gigantic - no other rocky planet in our system has anything like it. 05:59: ... Earth’s solid iron inner core spins suspended in a molten metal outer core, and this ... 08:02: Earth’s tilt seems just right - perhaps even rare.
	2019-10-21: Is Time Travel Impossible? 01:08: A fast-moving spaceship appears to experience a slower rate of time compared to someone waiting back on Earth. 01:22: But they’ll find a minimum of hundreds of thousands of years have passed when they get back to Earth.
	2019-09-30: How Many Universes Are There? 16:42: If Earth formed at 100 times its current distance from the sun it wouldn't have cleared its orbit either, and so wouldn't be considered a planet.
	2019-09-23: Is Pluto a Planet? 01:53: Note that they did NOT include the Earth. 02:07: ... “On the Revolutions of the Heavenly Spheres” which cast the Sun, not the Earth, as the center of the universe and the Earth in its proper place among ... 16:19: After all, it's closer in mass to the Earth and has an atmosphere - albeit a searing hot, horribly acidic one.
	2019-09-16: Could We Terraform Mars? 01:34: Mars’ current atmospheric pressure is 0.6% that of Earth – and that means circulatory shutdown within a minute for an unprotected humans. 01:55: On Earth that same light first bounces around in our thick atmosphere, heating it up. 02:15: And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous ultraviolet radiation from the Sun. 02:26: So, the most important step in terraforming Mars is to give it an atmosphere – ideally as close to Earth’s as possible. 03:16: Earth 2.0 OK, not so fast. 03:33: At 11% the mass of Earth, it has a weaker gravitational field that grips less tightly to an atmosphere. 03:39: ... small size means that the Martian core cooled down more quickly than Earth’s core, solidifying long ago and shutting down its global magnetic ... 03:49: Earth’s magnetic field protects us from the solar wind, as we saw in a recent episode. 04:47: They assess whether release of the accessible CO2 reserves could get Mars anywhere near Earth’s atmospheric pressure. 05:58: Unlike, for example, Earth’s permafrost, this stuff wouldn’t just melt under global warming. 06:10: At any rate, even if we managed to heat the entire regolith across the entire Martian surface we’d only get 4% of the Earth’s atmospheric pressure. 07:12: We need about 10,000 kg of material per square meter to duplicate Earth’s atmospheric pressure. 08:31: Several thousand times the total annual energy consumption of the entire Earth. 10:06: ... blue-green algae – cyanobacteria - was responsible for first oxygenating Earth’s ... 11:11: Nitrogen is much better - it works great on Earth anyway, but Mars has very little of the stuff. 12:29: Hopefully with exquisite aim, otherwise Earth is in for a pounding, also. 13:40: Would we really muster the resources to terraform Mars if we can’t do the same to re-terraform Earth? 14:16: ... a proponent of centrifuge cities – mag-lev rotating habitats to simulate Earth gravity. Also shown rather beautifully in this more practical design by ... 15:17: And inside each bubble an oasis – a lush, snow-globe replica of old Earth. 17:59: For now, let's move on to the possible flipping of Earth's North and South magnetic poles. 18:29: ... magnetic force-shield isn't nearly as strong as Earth's, however, so our Venusian floating cloud cities had better still have ... 03:16: Earth 2.0 OK, not so fast. 14:16: ... a proponent of centrifuge cities – mag-lev rotating habitats to simulate Earth gravity. Also shown rather beautifully in this more practical design by James ... 18:06: ... EarthKnight points out that while Venus lacks an Earth-type intrinsic magnetic ... 18:16: That's a nice point, EarthKnight. 18:06: ... EarthKnight points out that while Venus lacks an Earth-type intrinsic magnetic field, the ... 00:13: Life will blossom in our path and eventually the galaxy will shimmer with beautiful Earth-like orbs. 09:56: Our brand new CO2-oxygen atmosphere is not exactly earth-like. 11:03: At any rate, to get a true Earth-like atmosphere we need a non-toxic filler molecule. 11:18: To really build an Earth-like atmosphere we have to turn our eyes to the rest of the solar system. 14:09: These would be tall enough to encapsulate entire cities, and importantly – plenty of Earth-like natural wilderness. 00:13: Life will blossom in our path and eventually the galaxy will shimmer with beautiful Earth-like orbs. 09:56: Our brand new CO2-oxygen atmosphere is not exactly earth-like. 11:03: At any rate, to get a true Earth-like atmosphere we need a non-toxic filler molecule. 11:18: To really build an Earth-like atmosphere we have to turn our eyes to the rest of the solar system. 14:09: These would be tall enough to encapsulate entire cities, and importantly – plenty of Earth-like natural wilderness. 11:03: At any rate, to get a true Earth-like atmosphere we need a non-toxic filler molecule. 11:18: To really build an Earth-like atmosphere we have to turn our eyes to the rest of the solar system. 14:09: These would be tall enough to encapsulate entire cities, and importantly – plenty of Earth-like natural wilderness. 00:13: Life will blossom in our path and eventually the galaxy will shimmer with beautiful Earth-like orbs. 02:15: And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous ultraviolet radiation from the Sun. 02:26: So, the most important step in terraforming Mars is to give it an atmosphere – ideally as close to Earth’s as possible. 03:39: ... small size means that the Martian core cooled down more quickly than Earth’s core, solidifying long ago and shutting down its global magnetic ... 03:49: Earth’s magnetic field protects us from the solar wind, as we saw in a recent episode. 04:47: They assess whether release of the accessible CO2 reserves could get Mars anywhere near Earth’s atmospheric pressure. 05:58: Unlike, for example, Earth’s permafrost, this stuff wouldn’t just melt under global warming. 06:10: At any rate, even if we managed to heat the entire regolith across the entire Martian surface we’d only get 4% of the Earth’s atmospheric pressure. 07:12: We need about 10,000 kg of material per square meter to duplicate Earth’s atmospheric pressure. 10:06: ... blue-green algae – cyanobacteria - was responsible for first oxygenating Earth’s ... 17:59: For now, let's move on to the possible flipping of Earth's North and South magnetic poles. 18:29: ... magnetic force-shield isn't nearly as strong as Earth's, however, so our Venusian floating cloud cities had better still have ... 02:15: And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous ultraviolet radiation from the Sun. 10:06: ... blue-green algae – cyanobacteria - was responsible for first oxygenating Earth’s atmosphere. ... 02:15: And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous ultraviolet radiation from the Sun. 04:47: They assess whether release of the accessible CO2 reserves could get Mars anywhere near Earth’s atmospheric pressure. 06:10: At any rate, even if we managed to heat the entire regolith across the entire Martian surface we’d only get 4% of the Earth’s atmospheric pressure. 07:12: We need about 10,000 kg of material per square meter to duplicate Earth’s atmospheric pressure. 04:47: They assess whether release of the accessible CO2 reserves could get Mars anywhere near Earth’s atmospheric pressure. 06:10: At any rate, even if we managed to heat the entire regolith across the entire Martian surface we’d only get 4% of the Earth’s atmospheric pressure. 07:12: We need about 10,000 kg of material per square meter to duplicate Earth’s atmospheric pressure. 03:39: ... small size means that the Martian core cooled down more quickly than Earth’s core, solidifying long ago and shutting down its global magnetic ... 03:49: Earth’s magnetic field protects us from the solar wind, as we saw in a recent episode. 17:59: For now, let's move on to the possible flipping of Earth's North and South magnetic poles. 05:58: Unlike, for example, Earth’s permafrost, this stuff wouldn’t just melt under global warming. 18:06: ... points out that while Venus lacks an Earth-type intrinsic magnetic field, the solar wind striking its atmosphere creates ...
	2019-09-03: Is Earth's Magnetic Field Reversing? 00:00: Earth’s magnetic field protects us from deadly space radiation. 00:20: Spaceship Earth has a literal deflector shield. 00:46: Now, that’s helpful, because Earth is constantly bombarded by very fast moving charged particles, especially coming from the Sun. 01:10: So what would happen if Earth lost its field? 01:56: Magnetic materials like iron often form with their natural fields aligned with Earth’s field. 02:02: We can track the direction of Earth’s magnetic field in sedimentary layers and in old volcanic flows. 02:09: ... out Earth’s field has completely flipped direction 183 times over the past 84 ... 02:54: And for that we need to understand the Earth’s magnetic field. 03:26: But Earth’s interior is not intrinsically magnetic – its too hot for the iron atoms in the core to spontaneously align. 03:41: How, then, does the Earth generate such a gigantic and well-organized dipole magnetic field? 03:48: Let’s start with a quick review of what the interior of the Earth look like. 03:53: Beneath the thin crust and 2900 km of solid mantle lies earth’s core. 04:48: The interior of the Earth is cooling down very slowly, which means the liquid outer core is freezing into the solid inner core. 05:03: These flows are then twisted into helixes by the coriolis force – the same effect that produces hurricanes on Earth’s surface. 05:10: ... all of this motion that together produces Earth’s magnetic field through a process called the dynamo effect – or so most ... 05:21: And dynamo theory not only explains geomagnetism, but also why Earth’s field sometimes reverses its polarity. 06:10: So if the entire core is rotating with the Earth then the magnetic field will also rotate. 06:47: Those loops form magnetic tubes around Earth’s rotational axis. 07:27: ... any rotating body with a fluid conductor can produce such a field – the Earth, but also the Sun with its flowing hydrogen plasma, or the liquid ... 07:50: In fact Earth’s magnetic field is a highly dynamic beast. 07:54: The north and south gomagnetic poles are close to the geographic poles – so, close to Earth’s rotation axis, but are not quite exactly aligned. 08:30: In fact, HOW can it flip? – surely the direction of the magnetic field depends on the direction Earth is spinning. 09:12: Earth’s magnetic field isn’t necessarily switched off, but it’s scrambled in some way. 10:57: ... international World Magnetic Model is a global maps of Earth’s magnetic field updated every 5 years – in the past that’s been frequent ... 12:24: ... scientists have a pretty good idea, and think that Earth’s magnetic field is likely to hold out for our lifetimes – and those of ... 13:04: ... a house made of millions of refrigerator magnets to protect us once the Earth’s magnetic field ... 03:41: How, then, does the Earth generate such a gigantic and well-organized dipole magnetic field? 01:10: So what would happen if Earth lost its field? 00:00: Earth’s magnetic field protects us from deadly space radiation. 01:56: Magnetic materials like iron often form with their natural fields aligned with Earth’s field. 02:02: We can track the direction of Earth’s magnetic field in sedimentary layers and in old volcanic flows. 02:09: ... out Earth’s field has completely flipped direction 183 times over the past 84 ... 02:54: And for that we need to understand the Earth’s magnetic field. 03:26: But Earth’s interior is not intrinsically magnetic – its too hot for the iron atoms in the core to spontaneously align. 03:53: Beneath the thin crust and 2900 km of solid mantle lies earth’s core. 05:03: These flows are then twisted into helixes by the coriolis force – the same effect that produces hurricanes on Earth’s surface. 05:10: ... all of this motion that together produces Earth’s magnetic field through a process called the dynamo effect – or so most ... 05:21: And dynamo theory not only explains geomagnetism, but also why Earth’s field sometimes reverses its polarity. 06:47: Those loops form magnetic tubes around Earth’s rotational axis. 07:50: In fact Earth’s magnetic field is a highly dynamic beast. 07:54: The north and south gomagnetic poles are close to the geographic poles – so, close to Earth’s rotation axis, but are not quite exactly aligned. 09:12: Earth’s magnetic field isn’t necessarily switched off, but it’s scrambled in some way. 10:57: ... international World Magnetic Model is a global maps of Earth’s magnetic field updated every 5 years – in the past that’s been frequent ... 12:24: ... scientists have a pretty good idea, and think that Earth’s magnetic field is likely to hold out for our lifetimes – and those of ... 13:04: ... a house made of millions of refrigerator magnets to protect us once the Earth’s magnetic field ... 03:53: Beneath the thin crust and 2900 km of solid mantle lies earth’s core. 01:56: Magnetic materials like iron often form with their natural fields aligned with Earth’s field. 02:09: ... out Earth’s field has completely flipped direction 183 times over the past 84 million ... 05:21: And dynamo theory not only explains geomagnetism, but also why Earth’s field sometimes reverses its polarity. 03:26: But Earth’s interior is not intrinsically magnetic – its too hot for the iron atoms in the core to spontaneously align. 00:00: Earth’s magnetic field protects us from deadly space radiation. 02:02: We can track the direction of Earth’s magnetic field in sedimentary layers and in old volcanic flows. 02:54: And for that we need to understand the Earth’s magnetic field. 05:10: ... all of this motion that together produces Earth’s magnetic field through a process called the dynamo effect – or so most scientists ... 07:50: In fact Earth’s magnetic field is a highly dynamic beast. 09:12: Earth’s magnetic field isn’t necessarily switched off, but it’s scrambled in some way. 10:57: ... international World Magnetic Model is a global maps of Earth’s magnetic field updated every 5 years – in the past that’s been frequent enough to ... 12:24: ... scientists have a pretty good idea, and think that Earth’s magnetic field is likely to hold out for our lifetimes – and those of some ... 13:04: ... a house made of millions of refrigerator magnets to protect us once the Earth’s magnetic field ... 00:00: Earth’s magnetic field protects us from deadly space radiation. 02:02: We can track the direction of Earth’s magnetic field in sedimentary layers and in old volcanic flows. 02:54: And for that we need to understand the Earth’s magnetic field. 05:10: ... all of this motion that together produces Earth’s magnetic field through a process called the dynamo effect – or so most scientists ... 07:50: In fact Earth’s magnetic field is a highly dynamic beast. 09:12: Earth’s magnetic field isn’t necessarily switched off, but it’s scrambled in some way. 10:57: ... international World Magnetic Model is a global maps of Earth’s magnetic field updated every 5 years – in the past that’s been frequent enough to ... 12:24: ... scientists have a pretty good idea, and think that Earth’s magnetic field is likely to hold out for our lifetimes – and those of some generations ... 13:04: ... a house made of millions of refrigerator magnets to protect us once the Earth’s magnetic field ... 07:54: The north and south gomagnetic poles are close to the geographic poles – so, close to Earth’s rotation axis, but are not quite exactly aligned. 06:47: Those loops form magnetic tubes around Earth’s rotational axis. 05:03: These flows are then twisted into helixes by the coriolis force – the same effect that produces hurricanes on Earth’s surface.
	2019-08-12: Exploring Arecibo in VR 180 00:00: We are somewhere very special for this week's episode. Check it out. It's the planet Earth!
	2019-07-25: Deciphering The Vast Scale of the Universe 00:05: For much of human history, people believed that the planet Earth was the center of the universe. 00:11: Earth is pretty big. 06:23: ... Earth, the Sun, and our solar system behind, we’re zipping past the hundreds of ...
	2019-07-01: Thorium and the Future of Nuclear Energy 02:49: ... dangerous on geological timescales, and there is literally no place on earth We can guarantee that containment vessels will be safe against ...
	2019-06-20: The Quasar from The Beginning of Time 00:04: ... volcanic rock, and this is one of the youngest patches of land on planet Earth, but that same geological event that built this land has provided another ... 00:53: To Hawaiians it is a sacred site. And to astronomers, it's where the Earth meets the universe. 05:12: ... of that light so that it was infrared by the time it reached the earth and this spectrograph. Their redshift tells us how long that light has ... 00:53: To Hawaiians it is a sacred site. And to astronomers, it's where the Earth meets the universe.
	2019-06-06: The Alchemy of Neutron Star Collisions 00:00: ... years it's become clear that the truth is even more mind-blowing many of Earth's heavy elements including most precious metals were produced in an even ... 02:47: ... for the production of most of these elements including those here on earth the process is suitably awesome let's take a look like I said neutron ... 00:00: ... years it's become clear that the truth is even more mind-blowing many of Earth's heavy elements including most precious metals were produced in an even ... 02:47: ... a recent nature paper by marker and Bartos has clarified the origin of Earth's heavy elements even further in fact they figured out that some of our ... 00:00: ... years it's become clear that the truth is even more mind-blowing many of Earth's heavy elements including most precious metals were produced in an even more ... 02:47: ... a recent nature paper by marker and Bartos has clarified the origin of Earth's heavy elements even further in fact they figured out that some of our our ... 00:00: ... years it's become clear that the truth is even more mind-blowing many of Earth's heavy elements including most precious metals were produced in an even more spectacular ... 02:47: ... a recent nature paper by marker and Bartos has clarified the origin of Earth's heavy elements even further in fact they figured out that some of our our process ...
	2019-05-16: The Cosmic Dark Ages 02:31: ... This is how we think it actually played out. I’ll come back to how on Earth we could possibly know this in a ...
	2019-05-01: The Real Science of the EHT Black Hole 03:50: ... you build an interferometer that spans the planet Earth the wavelength you need in order to get this resolution is around 1mm, ... 08:14: The ring is the photon sphere, blurred due to the fact that this observation is incredibly difficult and the EHT is “only” the size of the Earth.
	2019-04-03: The Edge of an Infinite Universe 18:09: To make matters worse, the Earth would be falling apart at the same time.
	2019-03-28: Could the Universe End by Tearing Apart Every Atom? 10:03: ... the last 30 minutes phantom energy is strong enough to overcome Earth's own gravitational binding energy and the planet is disrupted. Moments ...
	2019-03-13: Will You Travel to Space? 03:12: [RICHARD] Everybody I know who's been into space who said it was earth changing, to be able to be in space looking back on it. 03:21: ... been into space. And also, space I think can do a lot to protect the Earth. ... 12:37: It's a hell of a time to be alive, watching humanity's first tentative steps off the Earth, and into the fringes of space time. 03:12: [RICHARD] Everybody I know who's been into space who said it was earth changing, to be able to be in space looking back on it.
	2019-01-30: Perpetual Motion From Negative Mass? 05:08: A negative mass apple would still fall to the Earth, and you wouldn’t notice Earth’s infinitesimal repulsion from the apple.
	2019-01-24: The Crisis in Cosmology 03:53: ...whose distances can be figured using stellar parallax Tracking their tiny motions on the sky, as Earth orbits the Sun.
	2018-12-20: Why String Theory is Wrong 16:28: ... right-handed replicators were the only game in town At least for the earth so have you accused us of filming that episode in a mirror universe ...
	2018-12-12: Quantum Physics in a Mirror Universe 00:02: ... time we talked about a wild notion for how life may have originated on earth perhaps it came from space let's see what you had to say about the ...
	2018-12-06: Did Life on Earth Come from Space? 00:03: ... that it only happened once in the entire galaxy and that once was not on earth what if primitive life arrived on earth after having traveled vast ... 00:37: ... are now dated to only a few hundred million years after the moment earth first became habitable is it really reasonable to imagine that evolution ...
	2018-11-21: 'Oumuamua Is Not Aliens 14:00: ... tau neutrino that had appeared to pass right through the center of the Earth. ...
	2018-11-14: Supersymmetric Particle Found? 00:39: ... there's only so much larger you can go, at least on the surface of the Earth. ... 05:01: Those cosmic rays lose energy to the CMB, which is partly why the most energetic cosmic rays are so rare here on earth. 05:32: Lower energy neutrinos can flow right through the Earth as though it isn't there. 06:49: ANITA is designed to detect neutrinos that are coming from below, passing through the earth into the ice sheet. 07:02: ... most energetic neutrinos coming in at an angle, skimming the arc of the earth on a shallow ... 07:19: That's because the most energetic neutrinos actually do lose energy passing through the earth. 09:07: A stau particle was produced on the opposite side of the planet by an incoming ultra high energy neutrino plowing into the earth. 09:15: The stau is theoretically capable of zipping straight through the earth before decaying into a regular tau lepton on the other side. 09:56: ... the Earth with enough high energy neutrinos, for example from a supernova ... 10:21: On the other hand, the supernova in question wasn't nearly bright enough to make even one earth penetrating ultra high energy neutrino likely. 10:42: Perhaps our understanding of neutrino propagation through the earth is flawed, or perhaps penguins use cell phones now. 10:21: On the other hand, the supernova in question wasn't nearly bright enough to make even one earth penetrating ultra high energy neutrino likely.
	2018-10-31: Are Virtual Particles A New Layer of Reality? 16:04: ... though, it's not right to say that it took the span of life on Earth for this fluke to happen-- as if we were rolling the dice every ...
	2018-10-25: Will We Ever Find Alien Life? 10:00: But you can look into the Rare Earth Hypothesis or the GIAIAN bottleneck hypothesis for some plausible proposals. 12:05: But I should also point out that this same massive access to technology that could kill us may also get humanity off the earth and onto other planets. 10:00: But you can look into the Rare Earth Hypothesis or the GIAIAN bottleneck hypothesis for some plausible proposals. 02:20: It'll find something like 20,000 new worlds, telling us once and for all how common earth-like planets really are. 02:48: We can't see this effect on earth-like planets yet, but the James Webb Space Telescope to launch in a year or so will get close to doing so. 02:20: It'll find something like 20,000 new worlds, telling us once and for all how common earth-like planets really are. 02:48: We can't see this effect on earth-like planets yet, but the James Webb Space Telescope to launch in a year or so will get close to doing so. 02:20: It'll find something like 20,000 new worlds, telling us once and for all how common earth-like planets really are. 02:48: We can't see this effect on earth-like planets yet, but the James Webb Space Telescope to launch in a year or so will get close to doing so.
	2018-10-10: Computing a Universe Simulation 14:56: Nameless wonders whether, in a 2D world, are there line Earthers.
	2018-08-30: Is There Life on Mars? 00:43: ... rock from the sun, it's currently just past its closest approach to Earth, making it an angry red eye in the early night ... 01:26: NASA's also planning a mission to take a sample of Martian soil and rocket it back to Earth. 04:00: Mars was at its closest approach to the sun and the Earth at its closest to Mars. 07:42: That analysis revealed chain structures that look an awful lot like Earth's microfossils. 12:22: So it's an intensely cold, intensely salty lake that even Earth's most hardy extremophile organisms would have trouble with. 12:57: It didn't take life that long to get started on Earth. 00:43: ... rock from the sun, it's currently just past its closest approach to Earth, making it an angry red eye in the early night ... 01:32: Applying our best earthbound technologies to an uncontaminated sample may provide the proof of Martian life we've always been hoping for. 07:42: That analysis revealed chain structures that look an awful lot like Earth's microfossils. 12:22: So it's an intensely cold, intensely salty lake that even Earth's most hardy extremophile organisms would have trouble with. 07:42: That analysis revealed chain structures that look an awful lot like Earth's microfossils.
	2018-08-23: How Will the Universe End? 02:13: ... in store for us, from disasters that will almost certainly befall the Earth, to the heating and death of the sun, to the merger with the Andromeda ...
	2018-08-15: Quantum Theory's Most Incredible Prediction 02:07: OK, first up, what on earth did I just say? 03:06: ... for example, a loop of wire with an electric current or the planet Earth with its dynamo ... 15:24: ... actually a pair of coronal mass ejections, a lesser one that reached the earth on August 29, 1859, and caused widespread auroral activity, and the big ... 15:51: ... usually take several days to cross the distance between Earth and the sun, and making its effect even more powerful than if it had ... 15:24: ... big one that occurred on the sun on September 1, 1859, and reached the earth 17.6 hours ...
	2018-08-01: How Close To The Sun Can Humanity Get? 01:00: 100 times Earth's diameter. 01:05: ... power stations, provide essentially, all of the energy to sustain Earth's ... 02:07: ... 1859, Earth's protective magnetosphere was disrupted by a massive coronal mass ... 02:19: Charged particles traveling at nearly 1% the speed of light bombarded the earth. 02:29: ... telegraph operators received electric shocks from currents induced by Earth's compressed magnetic ... 03:12: We already monitor it constantly with ground-based telescopes and spacecraft orbiting the earth or orbiting the sun at a safe distance. 06:33: To escape Earth's orbit in the outward direction, you first, need to escape Earth's gravitational pull and then, accelerate to achieve a larger orbit. 06:41: ... move closer to the sun, you need to first, escape the Earth and then, lose speed, which can be even trickier than gaining speed and ... 01:00: 100 times Earth's diameter. 01:05: ... power stations, provide essentially, all of the energy to sustain Earth's ... 02:07: ... 1859, Earth's protective magnetosphere was disrupted by a massive coronal mass ... 02:29: ... telegraph operators received electric shocks from currents induced by Earth's compressed magnetic ... 06:33: To escape Earth's orbit in the outward direction, you first, need to escape Earth's gravitational pull and then, accelerate to achieve a larger orbit. 01:05: ... power stations, provide essentially, all of the energy to sustain Earth's biosphere. ... 02:29: ... telegraph operators received electric shocks from currents induced by Earth's compressed magnetic ... 01:00: 100 times Earth's diameter. 06:33: To escape Earth's orbit in the outward direction, you first, need to escape Earth's gravitational pull and then, accelerate to achieve a larger orbit. 02:07: ... 1859, Earth's protective magnetosphere was disrupted by a massive coronal mass ejection, dubbed ...
	2018-07-11: Quantum Invariance & The Origin of The Standard Model 01:35: ... zero-- the bottom of the hill, sea level, even the center of the earth-- for the equations of motion of the ball, the altitude zero point is ...
	2018-07-04: Will A New Neutrino Change The Standard Model? 01:44: So, how on earth do you spot a sterile neutrino that doesn't even undergo that interaction-- well, by being extremely clever, obviously. 09:38: ... of muon to electron neutrinos as they travel through the body of the Earth. ... 12:14: A few of you wonder whether adding extra mass to Earth from asteroid mining could lead to problems like with our orbit or Earth's gravitational pull. 12:22: So Earth is around 2,000 times more massive than the entire asteroid belt. 12:26: Even if the entire belt were brought to Earth, you wouldn't notice the difference in gravity. 12:32: Only the very tiny fraction of precious and rare-earth elements are likely to be profitable to bring back to Earth. 12:14: A few of you wonder whether adding extra mass to Earth from asteroid mining could lead to problems like with our orbit or Earth's gravitational pull.
	2018-06-27: How Asteroid Mining Will Save Earth 02:09: ... regions and orbits in the inner solar system, including some that cross Earth's ... 02:25: They are the stuff of the terrestrial planets, the building blocks of worlds like the Earth that never managed to pull themselves together. 04:01: It's not that there's more of this stuff in asteroids than on Earth, it's just that it's more accessible. 04:07: See, the same differentiation process that led to M-type asteroids long ago sucked Earth's crust dry of many of these elements. 04:19: They followed iron into the core or mantle during Earth's formation. 04:34: In fact, much of the precious-metal content of Earth's crust came from old asteroid impacts. 05:39: ... rare-earth elements aren't actually all that rare in Earth's crust, most are dispersed in a way that makes sifting them out not ... 05:56: Asteroids are literal gold mines for stuff we want to bring back to Earth, but they also contain materials useful for the mining process itself. 06:04: ... nickel, aluminium, and titanium are not cost effective to bring back to Earth, but they can go towards building infrastructure in space, including more ... 06:19: Water dissociates into hydrogen and oxygen, becoming rocket fuel, which is critical for shipping mined resources back to Earth. 06:59: Fortunately for asteroid miners, though less fortunately for the dinosaurs, many asteroids do cross Earth's orbit in their passage around the Sun. 07:08: ... asteroids can be accessed with relatively little fuel expenditure from Earth orbit, and these will be the target of the first ... 08:15: ... asteroid, or we can nudge it into a more accessible orbit close to the Earth, perhaps even in orbit around the ... 10:26: ... resources and without the insane per-kilogram price tag of launch from Earth, perhaps the real work can begin of expanding humanity's reach into more ... 07:08: ... asteroids can be accessed with relatively little fuel expenditure from Earth orbit, and these will be the target of the first ... 08:52: Because if we learned how to land on and push an asteroid to a different course, we could potentially push an Earth-killing asteroid off course. 02:09: ... regions and orbits in the inner solar system, including some that cross Earth's ... 04:07: See, the same differentiation process that led to M-type asteroids long ago sucked Earth's crust dry of many of these elements. 04:19: They followed iron into the core or mantle during Earth's formation. 04:34: In fact, much of the precious-metal content of Earth's crust came from old asteroid impacts. 05:39: ... rare-earth elements aren't actually all that rare in Earth's crust, most are dispersed in a way that makes sifting them out not ... 06:59: Fortunately for asteroid miners, though less fortunately for the dinosaurs, many asteroids do cross Earth's orbit in their passage around the Sun. 04:07: See, the same differentiation process that led to M-type asteroids long ago sucked Earth's crust dry of many of these elements. 04:34: In fact, much of the precious-metal content of Earth's crust came from old asteroid impacts. 05:39: ... rare-earth elements aren't actually all that rare in Earth's crust, most are dispersed in a way that makes sifting them out not commercially ... 04:07: See, the same differentiation process that led to M-type asteroids long ago sucked Earth's crust dry of many of these elements. 04:19: They followed iron into the core or mantle during Earth's formation. 02:09: ... regions and orbits in the inner solar system, including some that cross Earth's orbit. ... 06:59: Fortunately for asteroid miners, though less fortunately for the dinosaurs, many asteroids do cross Earth's orbit in their passage around the Sun.
	2018-06-20: The Black Hole Information Paradox 14:58: HebaruSan noticed that, in our graphic, the Earth completed 1.75 orbits in the supposed 8 minutes it took the Sun's gravitational field to vanish.
	2018-06-13: What Survives Inside A Black Hole? 03:54: The Earth orbits the Sun, but more directly it orbits the Sun's gravitational field. 04:00: You could change anything about the Sun other than its mass and the Earth would continue in the same orbit. 04:06: If the Sun were to suddenly vanish, Earth would continue to orbit the existing gravitational field for 8 minutes. 04:12: The spacetime at the location of Earth's orbit would remain curved until the elastic fabric straightened itself out at the speed of light. 09:00: ... incredibly subtle frame dragging due to Earth's rotation has been detected, but it required the incredible precision and ... 03:54: The Earth orbits the Sun, but more directly it orbits the Sun's gravitational field. 04:12: The spacetime at the location of Earth's orbit would remain curved until the elastic fabric straightened itself out at the speed of light. 09:00: ... incredibly subtle frame dragging due to Earth's rotation has been detected, but it required the incredible precision and ... 04:12: The spacetime at the location of Earth's orbit would remain curved until the elastic fabric straightened itself out at the speed of light. 09:00: ... incredibly subtle frame dragging due to Earth's rotation has been detected, but it required the incredible precision and ...
	2018-05-16: Noether's Theorem and The Symmetries of Reality 04:07: ... gravitational field experienced by a satellite orbiting the earth-- then, Noether's theorem predicts another conserved quantity, angular ...
	2018-05-09: How Gaia Changed Astronomy Forever 01:37: The spacecraft orbits the sun at Lagrange point two, tracking the Earth's orbit, but 1.5 million kilometers further from the sun. 06:38: Based on the new data, we've already been able to confirm a gap in planetary radius size, at around 1.9 Earth radius. 01:37: The spacecraft orbits the sun at Lagrange point two, tracking the Earth's orbit, but 1.5 million kilometers further from the sun. 07:44: This is useful for future asteroid mining missions, and to identify potentially, Earth-threatening objects.
	2018-05-02: The Star at the End of Time 01:55: ... of 26 watts or around the energy equivalent of 20 million times the Earth's entire nuclear arsenal every ...
	2018-04-25: Black Hole Swarms 09:26: Majestic potato asked, whether a supernova can produce gravitational waves detectable from Earth?
	2018-04-18: Using Stars to See Gravitational Waves 04:17: The three components of this craft will trail behind the earth in an orbit around the sun. 04:26: That's roughly 10 times the distance from the Earth to the moon. 05:41: ... pulsars, neutron stars with jets that sweep past the Earth as the star processes, resulting in a sequence of flashes more regular ... 11:10: Life reduces the Earth's albedo, it's reflectivity. 11:14: Without life, Earth would reflect a higher intensity spectrum closer to the 6,000 Kelvin thermal spectrum it receives from the sun. 11:23: ... is, Earth, with the help of its absorbing biosphere, reprocesses a lot of that ... 11:10: Life reduces the Earth's albedo, it's reflectivity.
	2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!) 00:22: We can seek the answer in the chemistry of the early Earth or in the biology of the first cell. 03:06: ... the development of fossils over the nearly four billion years of life on Earth, we see clear as day the study trend toward greater complexity, from the ... 03:29: The Earth's biosphere, at least, becomes less boring over time. 03:47: But living organisms and indeed the Earth's biosphere are not closed. 04:08: On the other hand, the system of the Earth plus the sun is increasing in entropy. 05:13: The origin of life on Earth isn't known. 05:39: But where on Earth did this all happen? 05:44: Perhaps it was in tidal pools or around deep sea hydrothermal vents or even on the undersurface of Earth's ice caps. 05:58: The water of tidal pools is both cooled by the earth and the ocean and warmed by the sun. 06:04: Around deep sea vents, the searing gases from Earth's hot interior meet the frigid water of the ocean depths. 05:13: The origin of life on Earth isn't known. 03:29: The Earth's biosphere, at least, becomes less boring over time. 03:47: But living organisms and indeed the Earth's biosphere are not closed. 05:44: Perhaps it was in tidal pools or around deep sea hydrothermal vents or even on the undersurface of Earth's ice caps. 06:04: Around deep sea vents, the searing gases from Earth's hot interior meet the frigid water of the ocean depths. 03:29: The Earth's biosphere, at least, becomes less boring over time. 03:47: But living organisms and indeed the Earth's biosphere are not closed. 06:04: Around deep sea vents, the searing gases from Earth's hot interior meet the frigid water of the ocean depths. 05:44: Perhaps it was in tidal pools or around deep sea hydrothermal vents or even on the undersurface of Earth's ice caps.
	2018-03-28: The Andromeda-Milky Way Collision 01:21: But what about the sun, the solar system, the Earth? 06:50: But what about the sun and the earth? 08:29: Earth will long ago have been roasted by our own brightening and then expanding sun, which we talked about in earlier episodes.
	2018-03-07: Should Space be Privatized? 01:57: ... was encouraged to take over the day to day business of transport to Earth ...
	2018-02-28: The Trebuchet Challenge 03:51: As Archimedes once said, "give me a lever and a place to stand, and I will move the earth," or hurl a 90-kilogram stone over 300 meters.
	2018-02-21: The Death of the Sun 00:06: Earth is lifeless. 01:43: ... and brighten with disastrous consequences for the habitability of the Earth. ... 03:45: The sun is now a red giant, and it is vast on the Earth's daytime sky. 05:31: This time it's outer layers will reach Earth's orbit, and probably then some. 05:37: Earth gets gobbled? 05:54: ... it loses mass, its gravitational hold weakens and so the Earth's orbit expands, perhaps eventually taking it out beyond Mars' orbit, if ... 06:12: Earth is wreathed in the searing stellar winds. 06:25: ... Earth's own gravitational pull creates a tidal bulge in the sun that may ... 06:37: Theoretical models are still not entirely settled, but Earth's prospects look bleak. 07:11: The naked core of 100,000 Kelvin degenerate carbon and oxygen has collapsed to the size of the Earth. 07:28: ... the Earth-- perhaps it just managed to escape the expanding sun and is now a lonely ... 10:40: Does this mean that the combined system of the Earth plus you gains mass every time you jump, because you gain potential energy? 11:27: ... ground as the zero point, but we could equally make it the center of the Earth or a point infinitely far ... 03:45: The sun is now a red giant, and it is vast on the Earth's daytime sky. 05:31: This time it's outer layers will reach Earth's orbit, and probably then some. 05:54: ... it loses mass, its gravitational hold weakens and so the Earth's orbit expands, perhaps eventually taking it out beyond Mars' orbit, if ... 06:25: ... Earth's own gravitational pull creates a tidal bulge in the sun that may ... 06:37: Theoretical models are still not entirely settled, but Earth's prospects look bleak. 03:45: The sun is now a red giant, and it is vast on the Earth's daytime sky. 05:31: This time it's outer layers will reach Earth's orbit, and probably then some. 05:54: ... it loses mass, its gravitational hold weakens and so the Earth's orbit expands, perhaps eventually taking it out beyond Mars' orbit, if the sun ... 06:37: Theoretical models are still not entirely settled, but Earth's prospects look bleak.
	2018-02-14: What is Energy? 06:25: ... in gravitational potential energy, because that energy is stored in the Earth's gravitational ... 12:58: ... Brockman points out that 15 Earth masses of terrestrial material is a lot a planet for a star to consume, ... 13:14: In other star systems, we frequently see one or more super-Earths with several Earth masses each. 13:20: The Trappist 1 system has seven planets all close to or larger than the Earth. 12:58: ... Brockman points out that 15 Earth masses of terrestrial material is a lot a planet for a star to consume, at ... 13:14: In other star systems, we frequently see one or more super-Earths with several Earth masses each. 06:25: ... in gravitational potential energy, because that energy is stored in the Earth's gravitational ...
	2018-01-31: Kronos: Devourer Of Worlds 06:06: Oh et al. calculated that 15 Earth masses of raw Earth material would produce the observed abundances very nicely. 06:46: 15 Earth masses would about do the trick there as well. 07:36: ... brightening of the sun and the inevitable extinction of all life on Earth that will result. Or is it ... 08:08: ... wind while also magnetically driving the outflow towards the poles so Earth doesn't get ... 08:50: We just move the Earth. 08:59: It should be possible to deflect an asteroid into an elliptical orbit that takes it near both the Earth and Jupiter. 09:05: It tugs on the Earth gravitationally, increasing our angular momentum. 09:34: TheRealMirCat points out that if Earth is our only home by the time all of this happens, we deserve to burn. 08:08: ... wind while also magnetically driving the outflow towards the poles so Earth doesn't get ... 09:05: It tugs on the Earth gravitationally, increasing our angular momentum. 06:06: Oh et al. calculated that 15 Earth masses of raw Earth material would produce the observed abundances very nicely. 06:46: 15 Earth masses would about do the trick there as well. 06:06: Oh et al. calculated that 15 Earth masses of raw Earth material would produce the observed abundances very nicely. 05:54: The researchers tested the hypothesis by throwing a bunch of Earth-like planets into a sun-like star-- mathematically, I mean.
	2018-01-24: The End of the Habitable Zone 00:27: Hydrogen is fused into helium in the sun's core, producing energy that keeps it shining and keeps the earth warm and hospitable to life. 00:36: But that fuel will run out, after which the sun will swell into a red giant and flash fry the earth. 03:18: And what does this mean for the Earth? 04:55: About them oceans, currently Earth is comfortably inside the solar system's Goldilocks or habitable zone. 05:12: ... in the beginning when the sun was at 70% of its current brightness, Earth would have been outside the outer edge of the habitable zone, at least ... 05:33: Earth was highly habitable. 05:56: ... the early Earth had a much stronger greenhouse effect due to high carbon dioxide or ... 06:18: Whatever the solution, life has found a way to exist on Earth for at least 3 and 1/2 billion years. 06:28: The Goldilocks zone will expand beyond Earth's orbit. 07:00: Exactly when Earth loses all the oceans depends on complex climate models. 07:35: The surface of the earth becomes Arrakis, a single vast desert. 07:43: Currently there are several oceans worth of water locked in minerals within Earth's mantle. 08:03: ... the initial extinction wave from the loss of much of Earth's plant life, other complex multicellular organisms will succumb to heat, ... 09:20: But if we're talking about large scale geoengineering then I suppose we could also try to save the Earth. 07:00: Exactly when Earth loses all the oceans depends on complex climate models. 00:27: Hydrogen is fused into helium in the sun's core, producing energy that keeps it shining and keeps the earth warm and hospitable to life. 06:28: The Goldilocks zone will expand beyond Earth's orbit. 07:43: Currently there are several oceans worth of water locked in minerals within Earth's mantle. 08:03: ... the initial extinction wave from the loss of much of Earth's plant life, other complex multicellular organisms will succumb to heat, ... 07:43: Currently there are several oceans worth of water locked in minerals within Earth's mantle. 06:28: The Goldilocks zone will expand beyond Earth's orbit. 08:03: ... the initial extinction wave from the loss of much of Earth's plant life, other complex multicellular organisms will succumb to heat, ...
	2018-01-10: What Do Stars Sound Like? 02:27: Understanding helioseismology starts with regular old seismology on earth-- geoseismology. 02:34: ... earth, seismic waves are generated by earthquakes and can travel around the ... 03:20: The latter are closely analogous to ocean surface waves on the earth. 03:30: ... by turbulence just below the surface of a star, just as seismic waves on earth are created by earthquakes just below the surface in the ... 10:47: So before the break, we did an episode on what would happen to the earth if we were hit by a gamma ray burst beam. 11:02: He points out that they say the Earth's surface would be incinerated by such an event. 02:27: Understanding helioseismology starts with regular old seismology on earth-- geoseismology. 02:34: ... earth, seismic waves are generated by earthquakes and can travel around the planet as ... 03:30: ... the surface of a star, just as seismic waves on earth are created by earthquakes just below the surface in the ... 02:34: ... earth, seismic waves are generated by earthquakes and can travel around the planet as longitudinal pressure, or p-waves; ... 03:30: ... the surface of a star, just as seismic waves on earth are created by earthquakes just below the surface in the ... 02:34: ... earth, seismic waves are generated by earthquakes and can travel around the planet as longitudinal pressure, or p-waves; ... 03:30: ... the surface of a star, just as seismic waves on earth are created by earthquakes just below the surface in the ... 11:02: He points out that they say the Earth's surface would be incinerated by such an event.
	2017-12-20: Extinction by Gamma-Ray Burst 01:28: Every 100 million years or so, a good deal of Earth's life gets wiped out. 02:05: ... extinction 440 million years ago may have resulted from the Earth being blasted by the intense radiation jets from a distant exploding ... 03:16: Roughly once per day, the jet from such an explosion in a distant galaxy reaches the earth and is detected by the Swift or Fermi satellites. 04:54: ... including phytoplankton, the basis of the marine food chain and Earth's main oxygen ... 06:42: Whether or not this particular extinction event was due to a gamma-ray burst, we're pretty confident that the earth does get blasted periodically. 06:50: ... of stars in the Milky Way, it's estimated that every billion years, Earth finds itself in the path of between one and three GRBs within 10,000 ... 07:40: The fact that the spiral appears to be face on suggests that the axis of the entire system is pointed directly at the Earth. 08:16: Also, further observations with the Keck telescopes indicate that the system's orbital axis isn't pointed directly at the Earth. 11:14: It was moving much faster than most solar system objects, at around 50 kilometers per second, at its closest approach to Earth. 06:50: ... of stars in the Milky Way, it's estimated that every billion years, Earth finds itself in the path of between one and three GRBs within 10,000 light ... 01:28: Every 100 million years or so, a good deal of Earth's life gets wiped out. 04:54: ... including phytoplankton, the basis of the marine food chain and Earth's main oxygen ... 01:28: Every 100 million years or so, a good deal of Earth's life gets wiped out. 04:54: ... including phytoplankton, the basis of the marine food chain and Earth's main oxygen ...
	2017-12-13: The Origin of 'Oumuamua, Our First Interstellar Visitor 03:25: The earth, for example, has an eccentricity of 0.0167, giving us a nearly circular orbit. 04:57: PZ 17 performed computer simulations to find the frequency of such kicks sending objects close to the earth at such high speeds. 07:39: And based on this, PZ 17 predicts that two to 12 of these interstellar objects should pass through our solar system inside Earth's orbit every year. 07:49: The main reason we've only spotted one so far is that most don't get close enough to the earth for Pan Starrs to detect. 07:39: And based on this, PZ 17 predicts that two to 12 of these interstellar objects should pass through our solar system inside Earth's orbit every year.
	2017-11-29: Citizen Science + Zero-Point Challenge Answer 06:38: Multiply those together and you get that a gecko can support something like 40 newtons, or four kilograms, in Earth gravity.
	2017-11-22: Suicide Space Robots 05:22: Such vents on Earth's ocean floor host rich living ecosystems and may even have been the origin of life on Earth. 05:49: ... the remote chance that Cassini is carrying microbial contaminants from Earth and it crashes into Enceladus after de-commissioning, a sacrifice had to ... 01:10: Venus, with its dead searing hot atmosphere, is the most ravenous consumer of Earth-made landers. 05:22: Such vents on Earth's ocean floor host rich living ecosystems and may even have been the origin of life on Earth.
	2017-09-28: Are the Fundamental Constants Changing? 13:10: It would send a spacecraft to at least 550 times the Earth's orbital radius, out beyond the edge of the solar system.
	2017-09-20: The Future of Space Telescopes 01:14: ... determined that terrestrial planets-- that is, rocky planets like our Earth-- are extremely common and may orbit most stars in the Milky ... 01:41: Our sun is about 10 billion times brighter than Earth. 02:24: ... star, but no where near the factor of 10 billion difference between the Earth and the ... 04:01: So one of these things would allow us to see Earth in orbit around the sun from 60-light years away. 07:35: An aragoscope in geosynchronous orbit could resolve a hamster on the surface of the Earth. 08:46: ... use photon pressure to suspend a cloud of tiny reflective particles in Earth's ... 04:08: There are a couple of thousand stars within that range, and hundreds of sun-like stars, many of which certainly have Earth-like planets. 04:30: Besides Earth-like exoplanets, the starshade would also be an enormous help in studying quasars and other high-contrast phenomena. 04:08: There are a couple of thousand stars within that range, and hundreds of sun-like stars, many of which certainly have Earth-like planets. 04:30: Besides Earth-like exoplanets, the starshade would also be an enormous help in studying quasars and other high-contrast phenomena. 04:08: There are a couple of thousand stars within that range, and hundreds of sun-like stars, many of which certainly have Earth-like planets. 08:46: ... use photon pressure to suspend a cloud of tiny reflective particles in Earth's ...
	2017-09-13: Neutron Stars Collide in New LIGO Signal? 02:50: When those jets sweep past the Earth, we see the regular flashes of a pulsar. 11:05: ... one that may have birthed a new black hole and created half the Earth's mass in ...
	2017-08-24: First Detection of Life 00:23: The earth. 00:33: [THEME MUSIC] In December of 1990, during its first gravity assist flyby, the Jupiter-bound Galileo spacecraft turned its eye towards the earth. 00:47: ... by, among others, Carl Sagan, Galileo would measure the spectrum of Earth's atmosphere, take pictures, and look for radio emission during this brief ... 01:29: But first, let's talk about what life on Earth looks like to an observer in space. 01:47: ... spectrometer you can see these deep dips that result from molecules in Earth's atmosphere absorbing specific wavelengths of light from what would ... 02:31: While some of these molecules are known to arise from life on Earth, their presence isn't enough to confirm life on another planet. 04:33: On Earth, we know it comes from nitrogen-fixing bacteria and algae. 04:38: Of course, these are just the disequilibria that we find on earth. 05:16: Even if we ignore the fact that all Earth life requires it, water is by far the best substance in the universe for brewing up and supporting life. 06:06: Galileo also observed the spectrum of Earth's surface and took color photographs. 06:26: Galileo even captured radio signatures from Earth. 06:41: It proved the existence of life on Earth. 05:16: Even if we ignore the fact that all Earth life requires it, water is by far the best substance in the universe for brewing up and supporting life. 08:45: We don't quite have the technology to analyze an Earth-like atmosphere around an Earth-like planet. 09:03: ... enable us for the first time to perform Sagan's 1990 experiment on an Earth-like alien ... 09:57: There are billions and billions of potentially water-bearing Earth-like planets in our galaxy alone. 08:45: We don't quite have the technology to analyze an Earth-like atmosphere around an Earth-like planet. 09:03: ... enable us for the first time to perform Sagan's 1990 experiment on an Earth-like alien ... 09:57: There are billions and billions of potentially water-bearing Earth-like planets in our galaxy alone. 09:03: ... enable us for the first time to perform Sagan's 1990 experiment on an Earth-like alien ... 08:45: We don't quite have the technology to analyze an Earth-like atmosphere around an Earth-like planet. 09:57: There are billions and billions of potentially water-bearing Earth-like planets in our galaxy alone. 00:47: ... by, among others, Carl Sagan, Galileo would measure the spectrum of Earth's atmosphere, take pictures, and look for radio emission during this brief ... 01:47: ... spectrometer you can see these deep dips that result from molecules in Earth's atmosphere absorbing specific wavelengths of light from what would ... 06:06: Galileo also observed the spectrum of Earth's surface and took color photographs. 00:47: ... by, among others, Carl Sagan, Galileo would measure the spectrum of Earth's atmosphere, take pictures, and look for radio emission during this brief flyby ... 01:47: ... spectrometer you can see these deep dips that result from molecules in Earth's atmosphere absorbing specific wavelengths of light from what would otherwise be the ... 06:06: Galileo also observed the spectrum of Earth's surface and took color photographs.
	2017-08-16: Extraterrestrial Superstorms 00:06: ... Earth has its share of monster storms, but even the most powerful hurricanes ... 00:22: The great vortices of the Jovian planets are true storms, analogous in many ways to Earth's hurricanes. 00:34: ... stretching an incredible two to three times the diameter of the planet Earth. ... 01:22: In fact, let's start with those found on Earth. 01:45: In the case of earth storms, the energy powering that convection comes from the sun-warmed ocean. 01:59: These incoming winds travel such large distances across the Earth's surface that they are subject to the Coriolis force. 02:06: Earth is, of course, rotating on its axis. 02:34: The result is a raging vortex in the same direction as the Earth's rotation, clockwise in the southern hemisphere and counterclockwise in the north. 04:50: ... Earth, the only source of condensation is water, but the gas giants' ... 05:27: On Earth, the troposphere is about 10 miles thick. 06:07: Even high-pressure, outward-blowing storms don't dry up like they do on Earth. 07:16: In the 1800s, it spanned 37,000 kilometers, or about three Earths in width. 07:22: However, as of April this year, the spot spans just 16,350 kilometers, or 1.3 Earths. 01:45: In the case of earth storms, the energy powering that convection comes from the sun-warmed ocean. 00:22: The great vortices of the Jovian planets are true storms, analogous in many ways to Earth's hurricanes. 01:59: These incoming winds travel such large distances across the Earth's surface that they are subject to the Coriolis force. 02:34: The result is a raging vortex in the same direction as the Earth's rotation, clockwise in the southern hemisphere and counterclockwise in the north. 07:16: In the 1800s, it spanned 37,000 kilometers, or about three Earths in width. 07:22: However, as of April this year, the spot spans just 16,350 kilometers, or 1.3 Earths. 00:22: The great vortices of the Jovian planets are true storms, analogous in many ways to Earth's hurricanes. 02:34: The result is a raging vortex in the same direction as the Earth's rotation, clockwise in the southern hemisphere and counterclockwise in the north. 01:59: These incoming winds travel such large distances across the Earth's surface that they are subject to the Coriolis force.
	2017-08-02: Dark Flow 01:57: Actually, when we look at the CMB from our moving platform of planet Earth, we don't see a perfectly even temperature.
	2017-07-26: The Secrets of Feynman Diagrams 13:24: Lewinham asks what the real problem is with filling low earth orbit with debris. 13:28: So the issue is that stuff in low earth orbit is moving it around 8 kilometers per second. 13:24: Lewinham asks what the real problem is with filling low earth orbit with debris. 13:28: So the issue is that stuff in low earth orbit is moving it around 8 kilometers per second.
	2017-07-19: The Real Star Wars 01:00: One in which the space around the Earth became highly militarized and, in fact, massively weaponized. 12:12: There's a serious risk of wreathing the earth in a growing shell of mangled silicon and metal. 12:23: The Cold War arms race was on track to fill Earth's orbit with satellite-destroying weaponry and nuclear warheads.
	2017-06-21: Anti-Matter and Quantum Relativity 06:15: To begin with, what on earth were those two extra degrees of freedom in the four-component electron? 13:05: Also, those wide spots near the center of the map are the result of Doppler shift due to Earth's motion through space.
	2017-05-17: Martian Evolution 03:01: Mars is very different to Earth. 03:16: Mars has a surface gravity 38% that of Earth. 03:25: Strength may not be as strongly selected for as it is on Earth. 05:35: OK, gravity isn't the only difference between Mars and Earth. 06:01: This is especially true if we eventually terraform Mars because probably whatever atmosphere we build won't be as thick as Earth's. 06:49: ... the other hand, the less intense sunlight at Mars compared to Earth means it'll be harder to produce vitamin D. This factor is believed to ... 07:53: An increased mutation rate may mean evolution proceeds faster on Mars than it does on Earth. 08:06: The human immune system is constantly being exercised by exposure to Earth's biosphere, which contains countless bacteria and viruses. 08:36: And this effect may actually speed up their divergence from the humans of Earth. 08:42: ... of Mars, there will be an inevitable drift between the Martian and Earth ... 09:12: This effect will be amplified on Mars because the intermixing with Earth populations will be minimal. 09:18: Earth will quickly become a deadly place for Martians. 09:21: They'll find Earth's nearly three times higher gravity incredibly uncomfortable. 09:36: The inevitable divergence between Earth and Mars will eventually lead to speciation. 10:05: And they shared Earth with us for millennia. 13:33: The typical blurring of Earth's atmosphere is one to two arcseconds, which makes it tough. 14:08: venkata asks why the eclipse shadow moves from east to west rather than west to east as you might expect due to the rotation of the Earth. 14:15: In fact, it's the moon's orbit around the Earth that results in the shadow's movement. 14:20: The moon orbits the Earth once a month, which means it moves about 0.5 degrees per hour. 14:36: And that's from one position on the Earth. 08:42: ... of Mars, there will be an inevitable drift between the Martian and Earth populations. ... 09:12: This effect will be amplified on Mars because the intermixing with Earth populations will be minimal. 05:30: Perhaps Martian humans will end up much taller than their earthling forebears. 09:30: This later will also make them very wary about allowing earthling visitors to Mars. 08:32: Future Martians will be highly susceptible to earthly diseases. 05:30: Perhaps Martian humans will end up much taller than their earthling forebears. 09:30: This later will also make them very wary about allowing earthling visitors to Mars. 05:30: Perhaps Martian humans will end up much taller than their earthling forebears. 09:30: This later will also make them very wary about allowing earthling visitors to Mars. 08:32: Future Martians will be highly susceptible to earthly diseases. 06:01: This is especially true if we eventually terraform Mars because probably whatever atmosphere we build won't be as thick as Earth's. 08:06: The human immune system is constantly being exercised by exposure to Earth's biosphere, which contains countless bacteria and viruses. 09:21: They'll find Earth's nearly three times higher gravity incredibly uncomfortable. 13:33: The typical blurring of Earth's atmosphere is one to two arcseconds, which makes it tough. 08:06: The human immune system is constantly being exercised by exposure to Earth's biosphere, which contains countless bacteria and viruses.
	2017-05-10: The Great American Eclipse 00:52: A lunar eclipse is when the Earth's shadow falls on the moon. 00:56: A solar eclipse is when the moon's shadow falls on the Earth. 01:00: ... moon has to be on the opposite side of the Earth compared to the sun to catch the Earth's shadow and so lunar eclipses ... 01:08: And the moon has to be between the sun and the Earth for its shadow to hit us. 01:26: The moon's orbit about the Earth and the Earth's orbit about the sun, the ecliptic plane, are misaligned by about 5 degrees. 01:33: Most months, the moon's shadow misses the Earth. 01:58: It'll be partial because the Earth won't completely covered the sun from the moon's perspective. 04:12: The moon's orbit is elliptical, and so sometimes it eclipses the sun when it's a bit further away from the Earth. 04:40: Every year, the moon steals a little bit of Earth's rotational kinetic energy and drifts about 3.8 centimeters away from us. 04:54: In fact, in only half a billion years, the Earth will have its final total solar eclipse. 01:00: ... moon has to be on the opposite side of the Earth compared to the sun to catch the Earth's shadow and so lunar eclipses are always ... 00:52: A lunar eclipse is when the Earth's shadow falls on the moon. 01:00: ... to be on the opposite side of the Earth compared to the sun to catch the Earth's shadow and so lunar eclipses are always during full ... 01:26: The moon's orbit about the Earth and the Earth's orbit about the sun, the ecliptic plane, are misaligned by about 5 degrees. 04:40: Every year, the moon steals a little bit of Earth's rotational kinetic energy and drifts about 3.8 centimeters away from us. 01:26: The moon's orbit about the Earth and the Earth's orbit about the sun, the ecliptic plane, are misaligned by about 5 degrees. 04:40: Every year, the moon steals a little bit of Earth's rotational kinetic energy and drifts about 3.8 centimeters away from us. 00:52: A lunar eclipse is when the Earth's shadow falls on the moon. 01:00: ... to be on the opposite side of the Earth compared to the sun to catch the Earth's shadow and so lunar eclipses are always during full ... 00:52: A lunar eclipse is when the Earth's shadow falls on the moon.
	2017-04-19: The Oh My God Particle 01:55: We're bathed in a very low level of this radiation due to naturally occurring radioactive elements in the Earth. 05:01: By now, we have a pretty good census of the types of cosmic rays that tend to hit the Earth. 05:33: At the lowest energies, the cosmos flings one particle every second per square meter of the Earth's surface. 06:00: We build artificial ones on Earth using giant rings and powerful magnetic fields. 08:29: Part of the challenge in understanding cosmic rays is that our atmosphere and magnetic field shield the surface of the earth so well. 08:39: ... astronauts traveling outside Earth's magnetosphere reported strange flashes of light, which may be due to ... 05:33: At the lowest energies, the cosmos flings one particle every second per square meter of the Earth's surface. 08:39: ... astronauts traveling outside Earth's magnetosphere reported strange flashes of light, which may be due to ... 05:33: At the lowest energies, the cosmos flings one particle every second per square meter of the Earth's surface.
	2017-04-05: Telescopes on the Moon 00:54: ... includes soil analysis, extreme ultraviolet observations of Earth's magnetosphere, exploration with an ill-fated Rover-- I'll come back to ... 01:25: Two, Earth's atmosphere blocks all but a few narrow windows of the electromagnetic spectrum. 01:34: And three, on earth, sunlight is scattered to make our blue sky. 01:43: In addition, nights are especially great because they last a month due to the moon being tightly locked with the Earth. 04:11: To start with, Earth's thick atmosphere is a powerful buffer against rapid changes in temperature. 06:13: They've already built a 1 foot prototype and are planning a much larger test telescope here on earth. 06:35: Liquid mirror telescopes already exist on earth. 07:11: Pointing options are still limited, but by taking advantage of Earth or the moon's rotation, it's possible to scan a narrow arc across the sky. 09:03: ... challenges with creative solutions, perhaps the moon will become the Earth's lookout tower, granting the clearest views of all the rest of space ... 11:03: Hydroelectric power plants on earth do it with the flow of space time that we experience as Earth's gravitational field. 01:34: And three, on earth, sunlight is scattered to make our blue sky. 00:54: ... includes soil analysis, extreme ultraviolet observations of Earth's magnetosphere, exploration with an ill-fated Rover-- I'll come back to ... 01:25: Two, Earth's atmosphere blocks all but a few narrow windows of the electromagnetic spectrum. 04:11: To start with, Earth's thick atmosphere is a powerful buffer against rapid changes in temperature. 09:03: ... challenges with creative solutions, perhaps the moon will become the Earth's lookout tower, granting the clearest views of all the rest of space ... 11:03: Hydroelectric power plants on earth do it with the flow of space time that we experience as Earth's gravitational field. 01:25: Two, Earth's atmosphere blocks all but a few narrow windows of the electromagnetic spectrum. 11:03: Hydroelectric power plants on earth do it with the flow of space time that we experience as Earth's gravitational field. 09:03: ... challenges with creative solutions, perhaps the moon will become the Earth's lookout tower, granting the clearest views of all the rest of space ... 00:54: ... includes soil analysis, extreme ultraviolet observations of Earth's magnetosphere, exploration with an ill-fated Rover-- I'll come back to that, and of ... 04:11: To start with, Earth's thick atmosphere is a powerful buffer against rapid changes in temperature.
	2017-03-22: Superluminal Time Travel + Time Warp Challenge Answer 04:46: We'll plot the world lines of these ships as recorded by someone waiting back on Earth. 04:51: Earth doesn't move from its own perspective. 05:02: At 50% lightspeed, the Annihilator would take 200 years to reach its destination, from Earth's perspective. 05:09: Meanwhile, your own world line remains on Earth as you build the paradox. 05:17: And so you've reached the exoplanet in 50 years from launch date, also from Earth's perspective. 06:34: ... Annihilator perceives itself as stationary and sees Earth racing away in the opposite direction at half light speed, while its ... 06:45: ... we know which spacetime interval contours it's on when it departs from Earth and arrives at its ... 07:38: One Paradox seems to race onwards towards its destination, while the other travels in reverse back towards Earth. 08:39: Let's return to the reference frame of the Earth to do this. 09:35: In this case, Earth's and then a near-lightspeed frame. 04:51: Earth doesn't move from its own perspective. 06:34: ... Annihilator perceives itself as stationary and sees Earth racing away in the opposite direction at half light speed, while its ... 05:02: At 50% lightspeed, the Annihilator would take 200 years to reach its destination, from Earth's perspective. 05:17: And so you've reached the exoplanet in 50 years from launch date, also from Earth's perspective. 09:35: In this case, Earth's and then a near-lightspeed frame. 05:02: At 50% lightspeed, the Annihilator would take 200 years to reach its destination, from Earth's perspective. 05:17: And so you've reached the exoplanet in 50 years from launch date, also from Earth's perspective.
	2017-03-15: Time Crystals! 00:58: But first up, what on earth are time crystals? 11:54: Yet it's estimated that a system with an Earth-like planet orbiting a Sun-like star has around a 1% chance of transiting from our perspective.
	2017-03-08: The Race to a Habitable Exoplanet - Time Warp Challenge 03:35: I recommend you start from the perspective of someone waiting around back at Earth. 03:57: ... example, if this is the world line from Earth's perspective of the first part of the Annihilator's journey during the ...
	2017-03-01: The Treasures of Trappist-1 01:52: The gravitational influence on each other allows us to figure out their masses, between 0.4 and 1.4 times Earth's mass. 03:08: Our solar system's habitable zone extends from roughly 1 astronomical unit-- so Earth's orbit-- to 1 and 1/2 AU, covering Earth and Mars. 05:53: Out here on Earth, our distance and our magnetosphere protect us from most of the sun's coronal mass ejections. 08:23: But this finding tells us that Earth sized planets are probably common around M dwarf stars. 00:10: A nearby red dwarf star was discovered to have not one, but seven Earth-like planets, and any of them may be capable of supporting life. 00:56: Never before have we seen so many Earth-like planets in one place. 08:14: Tidal locking, stellar activity, atmospheric composition, and volcanism can all turn an Earth-like planet uninhabitable. 08:29: Remember also that a potentially habitable Earth-like planet was recently found orbiting the very nearby Proxima Centauri. 00:10: A nearby red dwarf star was discovered to have not one, but seven Earth-like planets, and any of them may be capable of supporting life. 00:56: Never before have we seen so many Earth-like planets in one place. 08:14: Tidal locking, stellar activity, atmospheric composition, and volcanism can all turn an Earth-like planet uninhabitable. 08:29: Remember also that a potentially habitable Earth-like planet was recently found orbiting the very nearby Proxima Centauri. 08:14: Tidal locking, stellar activity, atmospheric composition, and volcanism can all turn an Earth-like planet uninhabitable. 08:29: Remember also that a potentially habitable Earth-like planet was recently found orbiting the very nearby Proxima Centauri. 08:14: Tidal locking, stellar activity, atmospheric composition, and volcanism can all turn an Earth-like planet uninhabitable. 00:10: A nearby red dwarf star was discovered to have not one, but seven Earth-like planets, and any of them may be capable of supporting life. 00:56: Never before have we seen so many Earth-like planets in one place. 01:52: The gravitational influence on each other allows us to figure out their masses, between 0.4 and 1.4 times Earth's mass. 03:08: Our solar system's habitable zone extends from roughly 1 astronomical unit-- so Earth's orbit-- to 1 and 1/2 AU, covering Earth and Mars. 01:52: The gravitational influence on each other allows us to figure out their masses, between 0.4 and 1.4 times Earth's mass. 03:08: Our solar system's habitable zone extends from roughly 1 astronomical unit-- so Earth's orbit-- to 1 and 1/2 AU, covering Earth and Mars.
	2017-02-22: The Eye of Sauron Reveals a Forming Solar System! 03:57: By the time it's at least 10% of the Earth's mass, it will have cleared its orbit of other planetesimals, and will have rounded out into a planet. 07:28: Dagon's highly eccentric 1,700 earth year orbit is larger than Neptune's. 07:34: ... a planet even at the lower end of Dagon's mass estimate, at around three earth ... 07:28: Dagon's highly eccentric 1,700 earth year orbit is larger than Neptune's. 03:57: By the time it's at least 10% of the Earth's mass, it will have cleared its orbit of other planetesimals, and will have rounded out into a planet.
	2017-02-15: Telescopes of Tomorrow 05:13: However, using telescopes within the Earth's atmosphere comes with complications. 08:49: We'll spot countless fast-moving objects in our own solar system, including potentially hazardous asteroids that could one day impact the Earth. 05:13: However, using telescopes within the Earth's atmosphere comes with complications.
	2017-01-19: The Phantom Singularity 02:49: Here on earth, the North and South pole are examples of coordinate singularities. 12:18: Be sure to check out the PBS "Infinite Series" episode dealing with earthly singularities right here.
	2017-01-11: The EM Drive: Fact or Fantasy? 10:39: ... if the 3,000 kilometer array can see an orange on the moon, an Earth-Mars interferometer could see that orange, well, crudely a structure 1,000 ...
	2017-01-04: How to See Black Holes + Kugelblitz Challenge Answer 04:59: An extremely advanced alien race has decided to destroy the Earth by enveloping it in a giant Kugelblitz, a black hole made entirely of lights. 05:08: They direct an intense shell of light inwards towards the Earth. 05:34: ... two, Project Disco Ball, proposes a satellite network orbiting the Earth at half the moon's orbit radius, capable of generating a reflective ... 08:00: In our Kugelblitz scenario, Earth won't even see the incoming shell of light until it reaches us. 08:06: Well, let's look at the scenarios for stopping the Kugelblitz before it consumes the Earth.
	2016-12-21: Have They Seen Us? 00:00: ... PLAYING] A century of Earth's radio transmissions has now washed over thousands of other star systems, ... 09:17: An alien civilization with their own SKA certainly couldn't watch Earth TV. 11:33: ... that case, Earth's TV bubble would be spotted within hours, or even minutes, of aliens ... 16:17: ... it's accepted to talk about the escape velocity at the surface of the Earth because we're used to Newtonian approximations ... 17:06: But the concept of escape velocity at the event horizon is still as meaningful as it is from the surface of the Earth. 11:56: It's pretty natural to want to scan the heavens at exactly the frequencies where we earthlings are the noisiest. 06:16: A signal that appears in one, but not the other, must be an earthly transmission. 11:56: It's pretty natural to want to scan the heavens at exactly the frequencies where we earthlings are the noisiest. 06:16: A signal that appears in one, but not the other, must be an earthly transmission. 00:00: ... PLAYING] A century of Earth's radio transmissions has now washed over thousands of other star systems, ... 11:33: ... that case, Earth's TV bubble would be spotted within hours, or even minutes, of aliens ... 00:00: ... PLAYING] A century of Earth's radio transmissions has now washed over thousands of other star systems, ...
	2016-12-14: Escape The Kugelblitz Challenge 04:10: Scenario-- a super-advanced alien civilization decides to build a giant black hole that will engulf the planet Earth. 04:23: So these guys plan to destroy the Earth with a kugelblitz, a black hole formed entirely from light. 04:37: This gigantic shell of light descends around the earth and will reach us in about a day. 05:10: From the inside, Earth has one second in which it notices absolutely nothing wrong before it's consumed in the singularity. 05:55: Plan A is to build an infinitely-strong Dyson sphere surrounding the earth just outside the moon's orbital radius. 06:19: ... a perfectly reflective, spherical force shield about halfway between the Earth and the ... 06:32: ... conservation of momentum, so the satellites don't get ricocheted back to Earth. ...
	2016-11-16: Strange Stars 02:28: These jets may sweep across the Earth due to the spinning-top-like procession of the neutron star. 06:51: It could be that neutron stars have an electroweak core, an apple-sized ball with the mass of two Earths in which quarks themselves burn.
	2016-11-09: Did Dark Energy Just Disappear? 14:13: ... cities will be an important touchstone in the conflict between Earthers and the .4g For True Martians ...
	2016-11-02: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers 03:00: ... technological civilization to have ever arisen within 100 light years of Earth, what would that tell us about the chance of such a civilization arising ... 05:11: ... neighborhood, and that others could only form on planets similar to the Earth, we get that there's a 1 in 100 chance of this happening on any given ... 05:25: So I'd take that as a very crude estimate of the maximum probability for Earth to have developed us. 05:34: No more likely than a 1 in 100 shot. Lucky Earth?
	2016-10-26: The Many Worlds of the Quantum Multiverse 11:37: I want to challenge you to prove that the Earth is round using an experiment.
	2016-10-19: The First Humans on Mars 02:25: It needs to be able to thrive, even if Earth is lost. 03:04: An important advantage of prefabricating habitats on Earth is that you can use advanced materials with better radiation shielding. 05:40: Mars's gravity is 0.38 times that of Earth. 05:55: To build a sustainable multigenerational civilization, it may be necessary to simulate Earth gravity. 07:10: ... or economically productive enough to justify continued life support from Earth. ... 05:55: To build a sustainable multigenerational civilization, it may be necessary to simulate Earth gravity.
	2016-10-12: Black Holes from the Dawn of Time 08:54: It's a different matter if one hit the Earth. 09:28: A billion-ton black hole has an event horizon around the size of a proton, so it would pass through the planet as though the Earth were made of air. 09:44: This should leave detectable traces in crystalline material in Earth's crust. 11:05: Parameth asks, "How can we prevent cross contamination between Earth organisms and Europa ones?" Well, this will take some serious care. 11:22: But perhaps we'll find life that's different enough to Earth life that there's no possibility that it was from some contamination. 11:37: Well, Europa's surface gravity is only about 13.5% that of Earth's. 11:43: So even at 100 kilometers depth, the pressure is only about 20% higher than at the deepest point of the Earth's ocean. 11:22: But perhaps we'll find life that's different enough to Earth life that there's no possibility that it was from some contamination. 11:05: Parameth asks, "How can we prevent cross contamination between Earth organisms and Europa ones?" Well, this will take some serious care. 09:44: This should leave detectable traces in crystalline material in Earth's crust. 11:37: Well, Europa's surface gravity is only about 13.5% that of Earth's. 11:43: So even at 100 kilometers depth, the pressure is only about 20% higher than at the deepest point of the Earth's ocean. 09:44: This should leave detectable traces in crystalline material in Earth's crust. 11:43: So even at 100 kilometers depth, the pressure is only about 20% higher than at the deepest point of the Earth's ocean.
	2016-10-05: Are We Alone? Galactic Civilization Challenge 01:36: ... we push the fossil record back closer and closer to the formation of the Earth and we see just how quickly life arose ... 02:43: Around 11 billion of those are Earth-like planets around Sun-like stars.
	2016-09-29: Life on Europa? 01:12: At least on Earth, liquid water is absolutely essential for life. 03:09: In fact, it may be that life on Earth started around its own hydrothermal vents. 03:21: ... volcanic vents in the deep ocean where noxious gases spew out from Earth's mantle and water temperatures exceed 100 degrees ... 03:45: Entire specialized ecosystems live around Earth's deep sea vents. 04:25: If we believe the iron-sulfur world hypothesis, then deep-sea vents may be where earth life first originated. 06:28: If Earth's ice-loving organisms are anything to judge by, then we're again talking single-celled organisms. 06:53: Life is found throughout earth's oceans. 04:25: If we believe the iron-sulfur world hypothesis, then deep-sea vents may be where earth life first originated. 01:12: At least on Earth, liquid water is absolutely essential for life. 03:09: In fact, it may be that life on Earth started around its own hydrothermal vents. 06:03: Another promising habitat for Europan life also has an earthly analog-- that's the undersurface of the ice. 03:21: ... volcanic vents in the deep ocean where noxious gases spew out from Earth's mantle and water temperatures exceed 100 degrees ... 03:45: Entire specialized ecosystems live around Earth's deep sea vents. 06:28: If Earth's ice-loving organisms are anything to judge by, then we're again talking single-celled organisms. 06:53: Life is found throughout earth's oceans. 03:45: Entire specialized ecosystems live around Earth's deep sea vents. 06:28: If Earth's ice-loving organisms are anything to judge by, then we're again talking single-celled organisms. 03:21: ... volcanic vents in the deep ocean where noxious gases spew out from Earth's mantle and water temperatures exceed 100 degrees ... 06:53: Life is found throughout earth's oceans.
	2016-09-21: Quantum Entanglement and the Great Bohr-Einstein Debate 11:29: OK, last week we talked about self-replicating spacecraft and why it may be surprising that none have found their way to earth. 13:05: The question then becomes, if Earth was seeded once, was it seeded only once? 13:18: All life on earth pretty clearly descended from the one self-replicating molecule type.
	2016-09-14: Self-Replicating Robots and Galactic Domination 07:36: ... random events that led to technological life dominating the Earth could have happened at least tens, but perhaps hundreds of millions of ... 08:04: ... if Earth is in the earliest 10% of these, that's thousands of civilizations ... 10:55: Paul Baba asks whether such a Dyson swarm would cause the Earth to freeze. 11:01: Well, a full Dyson swarm interior to Earth's orbit would, indeed, block sunlight and freeze our planet. 12:03: But even solar power stations at Earth's surface will soon be a viable solution for most of our current energy needs. 11:01: Well, a full Dyson swarm interior to Earth's orbit would, indeed, block sunlight and freeze our planet. 12:03: But even solar power stations at Earth's surface will soon be a viable solution for most of our current energy needs. 11:01: Well, a full Dyson swarm interior to Earth's orbit would, indeed, block sunlight and freeze our planet. 12:03: But even solar power stations at Earth's surface will soon be a viable solution for most of our current energy needs.
	2016-08-24: Should We Build a Dyson Sphere? 05:16: ... asteroids and outer solar system moons, too, assuming we want to leave Earth ...
	2016-08-17: Quantum Eraser Lottery Challenge 04:27: So maybe we bounce them between Earth and the moon, like, 8,000 times.
	2016-08-10: How the Quantum Eraser Rewrites the Past 10:48: Mircea Kitsune asks, what if a black hole was headed towards the Earth? 11:10: ... like that passing through the solar system, even if nowhere near the Earth, would probably disrupt planetary orbits and either rearrange or scatter ... 11:42: And one of these passing through the solar system would only be dangerous if it was moving slowly enough, and if it came very close to the Earth. 11:59: Tsjoencinema would like to know what would exactly happen if a gamma ray burst hit the earth. 12:23: Sure, Earth is certainly doomed. 12:25: The increasing temperature of the sun will cause all of Earth's oceans to evaporate in a billion years, plus or minus, depending on the model. 13:11: ... idea in which you collect asteroids and put them in orbit around the Earth, ready to sling at any oncoming impactors before they reach ... 12:25: The increasing temperature of the sun will cause all of Earth's oceans to evaporate in a billion years, plus or minus, depending on the model.
	2016-08-03: Can We Survive the Destruction of the Earth? ft. Neal Stephenson 00:22: Most of life on Earth is wiped out on a pretty regular basis. 01:03: But impactors are not the only existential threat to life on Earth. 03:01: ... obvious example would be just a big asteroid coming in and striking the Earth on short notice, which would be-- could be as destructive, or even more ... 05:09: We'd have to have facilities that were off-planet in the case of something that struck the Earth. 05:40: Space is trying to kill us, the Earth is trying to kill us, and at the moment we are trying to kill us. 06:13: ... 90% of objects larger than one kilometer in diameter that crossed Earth's ...
	2016-07-27: The Quantum Experiment that Broke Reality 12:52: For every eight Earth orbits, Venus does 13.
	2016-07-06: Juno to Reveal Jupiter's Violent Past 00:02: Two days ago on the 4th of July, 2016, the Juno spacecraft entered orbit around the planet, Jupiter after a five-year journey from Earth. 00:58: Today, we're going to see why, without Jupiter, Earth as we know it would not exist. 01:22: ... grew to at least 10 and maybe over 40 times the mass of the Earth before it had enough gravity to start holding on to the 300-ish Earth ... 02:02: It's 20,000 times the strength of Earth's field, giving Jupiter the brightest auroras in the solar system. 02:15: That's 5.2 times Earth's average distance from the sun. 02:39: ... Earth's own Milankovitch cycles, periodic changes in Earth's orbit and spin, are ... 03:03: Its powerful gravity clears up some of the most dangerous comets before they could collide with the Earth. 03:32: ... asteroids in the asteroid belt and can send them plummeting towards the Earth. ... 04:17: The planet migrates inwards in a similar way to a satellite falling to the Earth due to dragging against the upper atmosphere. 06:15: ... predict that a protoplanetary disk capable of forming Venus and Earth should also have formed another massive planet, at least half of Earth's ... 06:28: But Mars is a measly 10% of Earth's mass. 06:43: Another clue is that other real exoplanetary systems tend to have super Earths, rocky planets several times the mass of our own planet. 08:51: This is hypothesized to have caused the massive meteor activity of the late heavy bombardment, re-liquefying Earth's newly solidified crust. 09:13: ... have a tiny Mars, no super Earths, a weird, mixed up asteroid belt, and an early obliteration of Earth's ... 01:22: ... Earth before it had enough gravity to start holding on to the 300-ish Earth masses of hydrogen and helium that make up most of the planet ... 02:02: It's 20,000 times the strength of Earth's field, giving Jupiter the brightest auroras in the solar system. 02:15: That's 5.2 times Earth's average distance from the sun. 02:39: ... Earth's own Milankovitch cycles, periodic changes in Earth's orbit and spin, are ... 06:15: ... Earth should also have formed another massive planet, at least half of Earth's mass in Mars's ... 06:28: But Mars is a measly 10% of Earth's mass. 06:43: Another clue is that other real exoplanetary systems tend to have super Earths, rocky planets several times the mass of our own planet. 08:51: This is hypothesized to have caused the massive meteor activity of the late heavy bombardment, re-liquefying Earth's newly solidified crust. 09:13: ... have a tiny Mars, no super Earths, a weird, mixed up asteroid belt, and an early obliteration of Earth's ... 02:15: That's 5.2 times Earth's average distance from the sun. 02:02: It's 20,000 times the strength of Earth's field, giving Jupiter the brightest auroras in the solar system. 06:15: ... Earth should also have formed another massive planet, at least half of Earth's mass in Mars's ... 06:28: But Mars is a measly 10% of Earth's mass. 08:51: This is hypothesized to have caused the massive meteor activity of the late heavy bombardment, re-liquefying Earth's newly solidified crust. 02:39: ... own Milankovitch cycles, periodic changes in Earth's orbit and spin, are largely driven by Jupiter's influence and give us our ... 06:43: Another clue is that other real exoplanetary systems tend to have super Earths, rocky planets several times the mass of our own planet. 09:13: ... Earths, a weird, mixed up asteroid belt, and an early obliteration of Earth's surface, and, perhaps, a missing ninth ...
	2016-06-08: New Fundamental Particle Discovered?? + Challenge Winners! 05:52: Bookmaker talks about the connection between solar activity and Earth's climate. 07:17: In the paleoclimate record, we see that an increase in temperature due to Earth's changing orbit proceeds an increase in CO2. 05:52: Bookmaker talks about the connection between solar activity and Earth's climate. 07:17: In the paleoclimate record, we see that an increase in temperature due to Earth's changing orbit proceeds an increase in CO2. 05:52: Bookmaker talks about the connection between solar activity and Earth's climate.
	2016-05-25: Is an Ice Age Coming? 00:03: Earth's climate shifts between short periods of warm and long, long periods of frigid cold. 02:07: Earth's motion around the sun changes, and with it, the intensity and distribution of sunlight. 02:33: ... the elongation or the eccentricity of Earth's elliptical orbit shifts from almost completely circular to somewhat more ... 02:46: ... the absolute maximum eccentricity, Earth's most distant point from the sun-- the Aphelion-- is about 30% further ... 03:31: Two, the pointing of Earth's axis precesses. 03:41: In addition, the long axis of Earth's elliptical orbit also precesses. 04:07: And 3- Earth's tilt changes. 05:16: Each year's layer carries bubbles of the Earth's atmosphere from that time. 06:12: As Earth reached the depth of the current ice age, the cycle shifted. 06:26: Every time Earth's orbit becomes more circular, the planet warms and the glaciers go away. 07:55: Now, by themselves, shifts in Earth's orbit aren't enough to radically change climate. 08:05: As ice cover increases, Earth starts to reflect more incoming sunlight. 08:28: Cooler oceans are better at absorbing carbon dioxide from the atmosphere, and so the Earth's natural greenhouse effect is diminished. 08:59: Earth also moves slower at Aphelion, and so those long, cold winters are not counteracted by the short, warmer summers. 06:12: As Earth reached the depth of the current ice age, the cycle shifted. 08:05: As ice cover increases, Earth starts to reflect more incoming sunlight. 00:03: Earth's climate shifts between short periods of warm and long, long periods of frigid cold. 02:07: Earth's motion around the sun changes, and with it, the intensity and distribution of sunlight. 02:33: ... the elongation or the eccentricity of Earth's elliptical orbit shifts from almost completely circular to somewhat more ... 02:46: ... the absolute maximum eccentricity, Earth's most distant point from the sun-- the Aphelion-- is about 30% further ... 03:31: Two, the pointing of Earth's axis precesses. 03:41: In addition, the long axis of Earth's elliptical orbit also precesses. 04:07: And 3- Earth's tilt changes. 05:16: Each year's layer carries bubbles of the Earth's atmosphere from that time. 06:26: Every time Earth's orbit becomes more circular, the planet warms and the glaciers go away. 07:55: Now, by themselves, shifts in Earth's orbit aren't enough to radically change climate. 08:28: Cooler oceans are better at absorbing carbon dioxide from the atmosphere, and so the Earth's natural greenhouse effect is diminished. 05:16: Each year's layer carries bubbles of the Earth's atmosphere from that time. 03:31: Two, the pointing of Earth's axis precesses. 00:03: Earth's climate shifts between short periods of warm and long, long periods of frigid cold. 02:33: ... the elongation or the eccentricity of Earth's elliptical orbit shifts from almost completely circular to somewhat more elliptical ... 03:41: In addition, the long axis of Earth's elliptical orbit also precesses. 02:33: ... the elongation or the eccentricity of Earth's elliptical orbit shifts from almost completely circular to somewhat more elliptical in ... 03:41: In addition, the long axis of Earth's elliptical orbit also precesses. 02:07: Earth's motion around the sun changes, and with it, the intensity and distribution of sunlight. 08:28: Cooler oceans are better at absorbing carbon dioxide from the atmosphere, and so the Earth's natural greenhouse effect is diminished. 06:26: Every time Earth's orbit becomes more circular, the planet warms and the glaciers go away. 07:55: Now, by themselves, shifts in Earth's orbit aren't enough to radically change climate. 04:07: And 3- Earth's tilt changes.
	2016-05-18: Anti-gravity and the True Nature of Dark Energy 12:03: So a few people were wondering how that probe sends its signal back to Earth. 12:20: The signal will be weak, but we'll know exactly where to look and can use gigantic detectors here on Earth.
	2016-05-11: The Cosmic Conspiracy of Dark Energy Challenge Question 04:06: Dark energy has dominated the universe only during the tenure of life on Earth, although its effect has been felt for a bit longer than that.
	2016-05-04: Will Starshot's Insterstellar Journey Succeed? 02:19: This solar sail has buzzed past Venus and now explores the interplanetary space in an orbit between Earth and Venus. 06:00: It will take a 300 kilometer diameter telescope at Earth to get the same resolution. 06:40: ... need to know where to point the cameras and then beam that info back to Earth with whatever energy can be stored on ... 07:13: With a 20 plus year travel time and 4.4 years for the pics to be beamed back to Earth, that gets us the data in 45 to 50 years. 01:57: Light sails need no onboard propellant and the power generation stays back at home, whether it's the sun or an Earth-based laser.
	2016-04-20: Why the Universe Needs Dark Energy 09:31: So the universe is only expanding on the largest scales, not at all inside atoms, inside humans, the Earth-- even inside the Milky Way.
	2016-04-13: Will the Universe Expand Forever? 02:45: ... I throw it at 11 kilometers per second, which is the escape velocity on Earth's surface, then, by the time it almost stops moving, it will be so far ... 03:27: There's a minimum kinetic energy that the apple needs in order to escape the energy-sucking gravitational-potential well of the Earth. 12:35: ... elements that form the Earth and that form you may, in part, be from those supernovae, but more will ... 12:55: "Be humble, for you are made of Earth. 02:45: ... I throw it at 11 kilometers per second, which is the escape velocity on Earth's surface, then, by the time it almost stops moving, it will be so far ...
	2016-04-06: We Are Star Stuff 02:25: ... single one of them, the actual physical stuff of your body, of the Earth, of everything you can see, was at one point forged in one of the most ... 07:11: And collapse it does, taking about a tenth of a second to collapse from around the size of planet Earth to the size of a city. 09:45: ... blast of newly formed heavy matter, including something like 10% of the Earth's mass in ...
	2016-03-16: Why is the Earth Round and the Milky Way Flat? 00:05: The earth is clearly a sphere and yet the Milky Way is a disk. 01:07: ... has to factor in the changing direction of down due to the curvature of Earth's surface over its four mile ... 03:09: In fact, let's talk about the Earth. 03:12: The Earth is definitely a sphere, or pretty close to. 04:00: A block around halfway to the center of the Earth has to push up with the pressure needed to support the weight of 3,000 blocks above it. 06:18: Which the Earth isn't, but let's go with it. 07:31: The Earth and the Sun, for that matter, rotate on their axes. 07:51: In the case of the Earth, how flat does it get due to its spin? 07:55: ... the Equator the upward acceleration we feel due to the Earth's rotation is 0.03 meters per second squared, compared to 9.8 meters per ... 08:09: And indeed, the Equator is around 20 kilometers further from the center of the Earth than the pole, 0.3 percent of the total radius. 10:20: They don't just give us our beautiful globe of the Earth, our spiral Milky Way Galaxy. 12:26: This patch of space, the Milky Way, the Earth, has been bombarded with cosmic background radiation for all of cosmic time. 06:18: Which the Earth isn't, but let's go with it. 01:07: ... has to factor in the changing direction of down due to the curvature of Earth's surface over its four mile ... 07:55: ... the Equator the upward acceleration we feel due to the Earth's rotation is 0.03 meters per second squared, compared to 9.8 meters per ... 01:07: ... has to factor in the changing direction of down due to the curvature of Earth's surface over its four mile ...
	2016-03-02: What’s Wrong With the Big Bang Theory? 03:37: Nothing we could build on the surface of the Earth could do this.
	2016-02-17: Planet X Discovered?? + Challenge Winners! 01:31: ... very distant giant planet, with a mass well over 10 times that of the Earth, and a stretched out eccentric orbit with a period, a year-length, of ... 01:57: That's 700 times the Earth's average overall radius, placing it far outside the Kuiper Belt. 01:31: ... a stretched out eccentric orbit with a period, a year-length, of 15,000 Earth years, and an average distance to the Sun of 700 astronomical ... 01:57: That's 700 times the Earth's average overall radius, placing it far outside the Kuiper Belt.
	2016-02-11: LIGO's First Detection of Gravitational Waves! 01:35: Since then, ripples from mergers of black hole pairs in distant galaxies have changed the shape of spacetime here on Earth. 08:03: Venus' surface, or even cloud city gravity, is 90% that of Earth's.
	2016-02-03: Will Mars or Venus Kill You First? 00:19: The surface of planet Earth is an unusual place. 01:04: We'll start with Mars, because it sits in popular consciousness as our go-to Earth 2.0. 01:13: Mass is only 1/10 the mass of the Earth, and 40% of its surface gravity. 01:52: The atmospheric pressure on the surface of Mars is now around 0.5% of that of Earth. 06:56: It's a pleasant 0.9 times Earth's gravity, and the atmospheric pressure is around that of Earth's surface. 08:03: ... of a protective magnetic sheath around the planet, not as good as Earth, but not as bad as ... 08:25: We have it pretty sweet here on a Earth. 08:54: ... all of that high-energy craziness, then somehow found its way to planet Earth without having spent a lot of time traveling close to the speed of ... 01:04: We'll start with Mars, because it sits in popular consciousness as our go-to Earth 2.0. 06:56: It's a pleasant 0.9 times Earth's gravity, and the atmospheric pressure is around that of Earth's surface.
	2016-01-27: The Origin of Matter and Time 10:21: What happens when an astronaut does a round trip at a large fraction of the speed of light, and returns to compare her clock to one left on Earth?
	2016-01-06: The True Nature of Matter and Mass 06:44: Holding up our photon box against Earth's surface gravity has to be just as hard as trying to accelerate it at 1 g in empty space.
	2015-12-16: The Higgs Mechanism Explained 08:43: For the Earth, it's around 9 millimeters.
	2015-12-09: How to Build a Black Hole 11:20: Now, in the last full episode, we talked about how to stop a killer asteroid from hitting the earth. 12:18: ... that changing its velocity enough to hit the sun, or even to fall into Earth's orbit-- which was another suggestion-- would take vastly more energy ... 12:28: Sam Gilfellan wants know how large an object we'd need to destroy in order to form a ring system around the earth. 12:54: A ring system around the earth would be awesome. 12:18: ... that changing its velocity enough to hit the sun, or even to fall into Earth's orbit-- which was another suggestion-- would take vastly more energy ...
	2015-11-25: 100 Years of Relativity + Challenge Winners! 01:39: In our recent challenge episode, I asked whether you could save the Earth from a killer asteroid. 01:43: In a hypothetical scenario, the asteroid Apophis will buzz by the Earth in 2029 but then hit the Earth in 2036. 01:51: You were tasked with assessing the plausibility of saving the Earth with a gravitational tractor. 03:53: ... of minus 9 meters per second squared or around one ten billionth of Earth's surface ...
	2015-11-18: 5 Ways to Stop a Killer Asteroid 00:03: It's a scientific fact that the planet Earth will be hit by cataclysmic asteroids in the future. 00:11: ... Space is swarming with lots of really fast moving rocks, like the planet Earth, but also like that 19-meter-wide wide chunk, that blazed across the sky ... 01:31: At least 40,000 tons of it rains down on the Earth every year, mostly in the form of pebbles and smaller. 02:28: And most life on Earth dies. 02:40: Earth gets smacked this hard every 100 million years or so. 02:58: ... most of the biggest, one kilometer plus, comets or asteroids that cross Earth's ... 03:08: Those are called Near Earth Objects, or NEOs. 04:24: See, the Earth is a very small target on the scale of the solar system. 04:28: And Earth itself is moving pretty fast, traveling its own diameter once every seven minutes. 04:36: We need to slow it down or speed it up so that it is behind or in front of the Earth. 08:12: Science has given us such incredible power-- among other things, to serve as custodians of the planet Earth. 02:28: And most life on Earth dies. 03:08: Those are called Near Earth Objects, or NEOs. 02:58: ... most of the biggest, one kilometer plus, comets or asteroids that cross Earth's ...
	2015-11-11: Challenge: Can you save Earth from a Killer Asteroid? 00:18: The near-Earth asteroid, Apophis, is set to buzz by Earth on April 13, 2029 and then again exactly seven years later on April 13, 2036. 00:35: Apophis will still miss in 2029, but it will hit Earth head on in 2036. 01:14: ... we can pull Apophis just a couple of Earth diameters, say 25,000 kilometers, ahead of its expected position by the ... 02:39: Good luck saving planet Earth. 01:14: ... we can pull Apophis just a couple of Earth diameters, say 25,000 kilometers, ahead of its expected position by the impact ... 00:35: Apophis will still miss in 2029, but it will hit Earth head on in 2036.
	2015-11-05: Why Haven't We Found Alien Life? 01:36: We know of exactly one instance of intelligent life happening, the case of Earth. 02:32: ... Earth certainly required a number of very special conditions to build life and ... 03:42: ... around four billion years ago, pretty much just after the Earth had first cooled down from being a giant hellish magma bowl, we think ... 04:20: Basically, Earth was once a giant slimeball planet. 04:22: And it looks like Earth went from magma ball to slimeball in less than 300 million years. 04:40: ... has provided us with a perfect time capsule for studying the very early Earth, zircons-- super hard silicate crystals whose formation can be dated ... 05:33: ... explanations, but this is extremely suggestive that life was abundant on Earth remarkably soon after it first coalesced from stardust and that life ... 05:51: But either way, it looks like Earth became a slimeball teeming with life in a crazy short amount of time. 05:56: How on earth did this happen? 06:00: ... the genesis of life happens like that, and two, it didn't happen on Earth-- life was seeded from space, an idea called ... 06:19: A lot of the ejecta from Earth is going to be swarming in bugs. 06:23: Could similar bacterial astronauts have once survived an interstellar journey to Earth? 07:03: Earth was infested fast, so that means this stuff should be out there. 08:13: The clue might be that the Earth stayed a slimeball for nearly three billion years. 09:07: However, it's worth noting that we do have other species on Earth that seem to be moving down the same big brain path independently of humans. 09:33: ... over the full past and future history of star formation in our universe, Earth is ... 06:00: ... the genesis of life happens like that, and two, it didn't happen on Earth-- life was seeded from space, an idea called ... 05:33: ... explanations, but this is extremely suggestive that life was abundant on Earth remarkably soon after it first coalesced from stardust and that life either ... 08:13: The clue might be that the Earth stayed a slimeball for nearly three billion years. 04:40: ... has provided us with a perfect time capsule for studying the very early Earth, zircons-- super hard silicate crystals whose formation can be dated precisely by ... 09:19: ... life is common, then of the billions of Earth-like planets in the galaxy, only a tiny fraction needed to have a small head ... 09:33: ... all of the sun-like stars and Earth-like planets that will ever form over the full past and future history of ... 09:19: ... life is common, then of the billions of Earth-like planets in the galaxy, only a tiny fraction needed to have a small head ... 09:33: ... all of the sun-like stars and Earth-like planets that will ever form over the full past and future history of ... 09:19: ... life is common, then of the billions of Earth-like planets in the galaxy, only a tiny fraction needed to have a small head start on ... 09:33: ... all of the sun-like stars and Earth-like planets that will ever form over the full past and future history of star ... 00:26: ... nice, watery planets in the Milky Way and probably billions of them are Earth-sized planets around sun-like ...
	2015-10-22: Have Gravitational Waves Been Discovered?!? 02:47: So what on earth do g-waves even look like? 03:16: ... holes-- these make g-waves that lengthen or contract our space here on Earth by a factor of 10 to the power of minus 21 or ... 11:05: ... with Procyon Beta's bittersweet comment-- born too late to explore the Earth, born too early to explore the galaxy, born just in time to watch PBS ...
	2015-10-15: 5 REAL Possibilities for Interstellar Travel 01:11: So for argument's sake, let's say humanity's future is at stake, and we just discovered Earth 2.0 in the Alpha Centauri system.
	2015-10-07: The Speed of Light is NOT About Light 01:07: ... off by the Inquisition for his book supporting Copernicus and the whole, Earth is not the center of the universe, ... 01:30: Not only is Earth or, indeed, any other location not special, but Galileo posits that no velocity is special, either. 06:13: The Earth is whizzing around the sun, the sun around the Milky Way.
	2015-09-30: What Happens At The Edge Of The Universe? 06:01: The surface of the Earth looks pretty flat to us because we really can't see the curvature locally.
	2015-09-23: Does Dark Matter BREAK Physics? 07:14: ... have detectors here on Earth designed to catch the fall-out between the unthinkably rare collisions ...
	2015-08-19: Do Events Inside Black Holes Happen? 01:23: This is called gravitational time dilation and the same thing happens around Earth, just to a lesser degree. 01:44: ... pick up translational speed, just as I would if he were falling toward Earth. ... 05:16: Earth will freeze, of course, but its orbit won't be any different. 05:19: So as far as Earth is concerned, that black hole generates the same spacetime geometry out here that the Sun does. 05:52: One with the mass of Earth would have a radius of just under 1 centimeter. 06:43: But it's not because he's being sucked in any more than the Earth sucks in a falling apple. 06:48: As long as he stays outside the horizon, he can use rockets to hover or move radially outward just like on Earth. 11:46: ... full episode dealt with misconceptions about what causes ocean tides on Earth. ... 13:26: Madhu Sujan Paudel-- hope I pronounced that right-- and gottabweird both asked whether Earth's atmosphere then has tides. 13:33: ... and pressure variations on the atmospheric distribution around the Earth. ... 06:43: But it's not because he's being sucked in any more than the Earth sucks in a falling apple. 13:26: Madhu Sujan Paudel-- hope I pronounced that right-- and gottabweird both asked whether Earth's atmosphere then has tides.
	2015-08-05: What Physics Teachers Get Wrong About Tides! 00:38: The moon's gravity is stronger at Point A and weaker at Point B than it is at Earth's center. 00:42: ... net effect of this differential of the Moon's gravity across the Earth is to stretch the oceans out like taffy, ergo why the oceans bulge out ... 01:10: ... if Earth could rotate underneath those bulges with no friction between the ocean ... 02:18: Assumption three-- we're going to pretend the Earth is uniformly covered with one humongous ocean and no continents. 02:24: And finally, assumption four-- we're going to pretend that we can switch Earth's gravity on and off whenever we want to. 02:31: ... itself from the perspective of a frame of reference attached to Earth's ... 02:39: Forget about the oceans for a minute and just imagine two small blocks, A and B, at opposite ends of the Earth's surface along the Earth/Moon line. 02:47: Turn off Earth's gravity. 02:49: ... out in the ambient space, Block A accelerates toward the Moon more than Earth's center and Earth's center accelerates toward the Moon more than Block B. ... 03:11: It's an artifact of Earth's frame of reference. 03:13: Remember, Earth itself is accelerating towards the Moon, so according to Newton, Earth's frame is non-inertial. 03:23: But the bottom line is that in Earth's frame, the tidal force looks like anti-gravity, at least along the Earth/Moon line. 03:41: ... object's resulting acceleration relative to Earth's surface is called the total acceleration of that object, and it should ... 04:14: ... gravity along the Earth/Moon line works out to only 1/10,000,000th of an Earth g, and you can't lift something by pulling up on it with a force that's ... 04:28: Plus, even if you turned Earth's gravity off, you would never notice an outward acceleration of one micron per second per second. 04:50: But of course, the whole Earth is pulled that way by the Moon, chasing after the block. 04:54: So relative to the Earth's surface, the block's tidal acceleration is almost radially inward-- in other words, down. 05:01: In fact, if we map out the tidal acceleration vectors that you'd see at different points on Earth's surface, they look like this. 05:15: At most places, those vectors are largely tangent to Earth's surface, which would push water sideways. 05:26: Remember, the radially inward acceleration caused by Earth's own gravity on objects is 10 million times bigger. 07:00: Also, remember that Earth itself isn't perfectly rigid. 07:03: ... when water in a swimming pool rises a tiny amount, Earth's surface is also rising by tiny amount, making the change in water level ... 07:33: Now, when Earth, the Moon, and the Sun all line up in space, the effects are additive and you get extra-large spring tides. 07:45: Second, in the simple model of a water world Earth, the math says that the water level should vary by about 3/4 of a meter between high and low tide. 08:36: So are other things that I haven't mentioned, like how the rate of Earth's rotation and the ocean tides affect each other. 12:04: A lot of you wanted clarification on how curvature of time is what's responsible for, say, circular orbits around the Earth being geodesics. 12:21: ... that you take a frame attached to Earth's center, with clocks-- that frame's not going to be inertial-- and then ... 13:05: ... lot of you were expressing confusion about how two points on Earth's surface can both be "really" accelerating if Earth's surface itself is ... 13:18: In the Newtonian sense, acceleration would mean put a frame of reference at Earth's center. 13:22: ... relative to that clock, are the coordinate positions of two points on Earth's surface ... 13:46: For points on Earth's surface, that's not true. 14:13: ... why that seems to conflict with the idea of using a single frame at Earth's center and saying that those two points are not accelerating is that ... 04:14: ... pulling up on it with a force that's 10 million times smaller than its Earth weight. ... 00:42: ... like taffy, ergo why the oceans bulge out at opposite points along the Earth/Moon ... 01:00: ... model, there would be two tidal bulges at opposite ends of the Earth/Moon ... 02:39: Forget about the oceans for a minute and just imagine two small blocks, A and B, at opposite ends of the Earth's surface along the Earth/Moon line. 03:23: But the bottom line is that in Earth's frame, the tidal force looks like anti-gravity, at least along the Earth/Moon line. 03:50: But if that's true, the tidal force along the Earth/Moon line can't be raising or stretching the two bulges that lie along that line. 04:14: ... acceleration on objects due to the Moon's differential gravity along the Earth/Moon line works out to only 1/10,000,000th of an Earth g, and you can't lift ... 04:41: The key is to look at the tidal acceleration of objects that are not on the Earth/Moon line. 05:09: As you can see, tidal forces only act like anti-gravity if you're right on the Earth/Moon line. 05:51: Instead, thanks to the cumulative sideways traction everywhere else, it's being squeezed toward the Earth/Moon line and piling up there. 05:59: ... into a planet sized hydraulic pump and the ocean is bulging along the Earth/Moon line in the same way that a blister or a pimple will bulge up in the ... 00:38: The moon's gravity is stronger at Point A and weaker at Point B than it is at Earth's center. 01:10: ... rotate underneath those bulges with no friction between the ocean and Earth's crust, then at a given location on the globe, you would experience two ... 02:24: And finally, assumption four-- we're going to pretend that we can switch Earth's gravity on and off whenever we want to. 02:31: ... itself from the perspective of a frame of reference attached to Earth's ... 02:39: Forget about the oceans for a minute and just imagine two small blocks, A and B, at opposite ends of the Earth's surface along the Earth/Moon line. 02:47: Turn off Earth's gravity. 02:49: ... out in the ambient space, Block A accelerates toward the Moon more than Earth's center and Earth's center accelerates toward the Moon more than Block B. ... 03:11: It's an artifact of Earth's frame of reference. 03:13: Remember, Earth itself is accelerating towards the Moon, so according to Newton, Earth's frame is non-inertial. 03:23: But the bottom line is that in Earth's frame, the tidal force looks like anti-gravity, at least along the Earth/Moon line. 03:41: ... object's resulting acceleration relative to Earth's surface is called the total acceleration of that object, and it should ... 04:28: Plus, even if you turned Earth's gravity off, you would never notice an outward acceleration of one micron per second per second. 04:54: So relative to the Earth's surface, the block's tidal acceleration is almost radially inward-- in other words, down. 05:01: In fact, if we map out the tidal acceleration vectors that you'd see at different points on Earth's surface, they look like this. 05:15: At most places, those vectors are largely tangent to Earth's surface, which would push water sideways. 05:26: Remember, the radially inward acceleration caused by Earth's own gravity on objects is 10 million times bigger. 07:03: ... when water in a swimming pool rises a tiny amount, Earth's surface is also rising by tiny amount, making the change in water level ... 08:36: So are other things that I haven't mentioned, like how the rate of Earth's rotation and the ocean tides affect each other. 12:21: ... that you take a frame attached to Earth's center, with clocks-- that frame's not going to be inertial-- and then ... 13:05: ... lot of you were expressing confusion about how two points on Earth's surface can both be "really" accelerating if Earth's surface itself is ... 13:18: In the Newtonian sense, acceleration would mean put a frame of reference at Earth's center. 13:22: ... relative to that clock, are the coordinate positions of two points on Earth's surface ... 13:46: For points on Earth's surface, that's not true. 14:13: ... why that seems to conflict with the idea of using a single frame at Earth's center and saying that those two points are not accelerating is that ... 00:38: The moon's gravity is stronger at Point A and weaker at Point B than it is at Earth's center. 02:31: ... itself from the perspective of a frame of reference attached to Earth's center. ... 02:49: ... out in the ambient space, Block A accelerates toward the Moon more than Earth's center and Earth's center accelerates toward the Moon more than Block B. So ... 12:21: ... that you take a frame attached to Earth's center, with clocks-- that frame's not going to be inertial-- and then you work ... 13:18: In the Newtonian sense, acceleration would mean put a frame of reference at Earth's center. 14:13: ... why that seems to conflict with the idea of using a single frame at Earth's center and saying that those two points are not accelerating is that that frame ... 02:49: ... space, Block A accelerates toward the Moon more than Earth's center and Earth's center accelerates toward the Moon more than Block B. So from the perspective of Earth's ... 01:10: ... rotate underneath those bulges with no friction between the ocean and Earth's crust, then at a given location on the globe, you would experience two high ... 02:49: ... toward the Moon more than Block B. So from the perspective of Earth's frame, both blocks will separate from the surface as if acted on by some ... 03:11: It's an artifact of Earth's frame of reference. 03:13: Remember, Earth itself is accelerating towards the Moon, so according to Newton, Earth's frame is non-inertial. 03:23: But the bottom line is that in Earth's frame, the tidal force looks like anti-gravity, at least along the Earth/Moon line. 02:24: And finally, assumption four-- we're going to pretend that we can switch Earth's gravity on and off whenever we want to. 02:47: Turn off Earth's gravity. 04:28: Plus, even if you turned Earth's gravity off, you would never notice an outward acceleration of one micron per second per second. 08:36: So are other things that I haven't mentioned, like how the rate of Earth's rotation and the ocean tides affect each other. 02:39: Forget about the oceans for a minute and just imagine two small blocks, A and B, at opposite ends of the Earth's surface along the Earth/Moon line. 03:41: ... object's resulting acceleration relative to Earth's surface is called the total acceleration of that object, and it should be ... 04:54: So relative to the Earth's surface, the block's tidal acceleration is almost radially inward-- in other words, down. 05:01: In fact, if we map out the tidal acceleration vectors that you'd see at different points on Earth's surface, they look like this. 05:15: At most places, those vectors are largely tangent to Earth's surface, which would push water sideways. 07:03: ... when water in a swimming pool rises a tiny amount, Earth's surface is also rising by tiny amount, making the change in water level relative ... 13:05: ... lot of you were expressing confusion about how two points on Earth's surface can both be "really" accelerating if Earth's surface itself is not ... 13:22: ... relative to that clock, are the coordinate positions of two points on Earth's surface ... 13:46: For points on Earth's surface, that's not true. 13:22: ... relative to that clock, are the coordinate positions of two points on Earth's surface changing? ...
	2015-07-29: General Relativity & Curved Spacetime Explained! 00:27: ... says that a frame on earth's surface is inertial, and relative to that frame, a freely falling apple ... 00:40: So the apple's frame is inertial and the Earth frame is actually accelerating upward. 04:41: In contrast, the world line of a point on Earth's surface is not a geodesic. 04:48: So does that mean that Earth's surface has to be expanding radially? 04:52: In order to compare distant parts of the Earth, you'd need a single frame that extends across spacetime patches. 06:36: ... about space and time separately at all, most of the everyday effects on earth that Newton would attribute to gravity are due to curvature in ... 06:45: The 3D space around Earth is almost exactly Euclidean. 06:48: ... pictures that you see of Earth deforming a grid the way a bowling ball deforms a rubber sheet, or even ... 07:02: And around Earth, spacetime curvature manifests itself in clocks much more than in rulers. 06:48: ... pictures that you see of Earth deforming a grid the way a bowling ball deforms a rubber sheet, or even the ... 00:40: So the apple's frame is inertial and the Earth frame is actually accelerating upward. 07:02: And around Earth, spacetime curvature manifests itself in clocks much more than in rulers. 00:27: ... says that a frame on earth's surface is inertial, and relative to that frame, a freely falling apple ... 04:41: In contrast, the world line of a point on Earth's surface is not a geodesic. 04:48: So does that mean that Earth's surface has to be expanding radially? 00:27: ... says that a frame on earth's surface is inertial, and relative to that frame, a freely falling apple ... 04:41: In contrast, the world line of a point on Earth's surface is not a geodesic. 04:48: So does that mean that Earth's surface has to be expanding radially?
	2015-07-15: Can You Trust Your Eyes in Spacetime? 01:32: I'm not glued to Earth's surface. 01:34: The moon doesn't orbit Earth. 01:35: In fact, there is no Earth since Earth is held together by gravity. 01:32: I'm not glued to Earth's surface.
	2015-07-08: The Leap Second Explained 00:00: [MUSIC PLAYING] In an earlier episode, we mentioned the Earth's rotation is slowing down. 00:27: But Earth's rotation slows, so that's a bad definition. 01:05: ... then, though, Earth's actual day has gotten about 2 and 1/2 milliseconds longer so that by the ... 01:47: Of course, Earth's rotation has irregularities due to earthquakes and other effects. 01:54: Now, over time, Earth's rotation will keep slowing and leap seconds will become more frequent. 02:09: Earth is spinning down, yeah, but not that quickly. 01:47: Of course, Earth's rotation has irregularities due to earthquakes and other effects. 00:00: [MUSIC PLAYING] In an earlier episode, we mentioned the Earth's rotation is slowing down. 00:27: But Earth's rotation slows, so that's a bad definition. 01:05: ... then, though, Earth's actual day has gotten about 2 and 1/2 milliseconds longer so that by the ... 01:47: Of course, Earth's rotation has irregularities due to earthquakes and other effects. 01:54: Now, over time, Earth's rotation will keep slowing and leap seconds will become more frequent. 01:05: ... then, though, Earth's actual day has gotten about 2 and 1/2 milliseconds longer so that by the 1960s, ... 00:00: [MUSIC PLAYING] In an earlier episode, we mentioned the Earth's rotation is slowing down. 00:27: But Earth's rotation slows, so that's a bad definition. 01:47: Of course, Earth's rotation has irregularities due to earthquakes and other effects. 01:54: Now, over time, Earth's rotation will keep slowing and leap seconds will become more frequent. 00:27: But Earth's rotation slows, so that's a bad definition.
	2015-07-08: Curvature Demonstrated + Comments 04:36: For instance, the surface of Earth you can tell is curved by following the same procedure the ant does. 05:00: Therefore, you can determine just by living on Earth's surface that Earth's surface is a curved space. 05:18: ... that point in the video, the Earth it was shown was supposed to be the physical, three dimensional Earth, ... 05:27: ... you wanted to know if the three dimensional space around Earth is curved, you would follow the procedure of using Euclidean three ... 05:39: If you do, then the 3D space around Earth is flat. 05:42: But if you don't, then the 3D space around Earth is curved. 06:01: Take two lines that are at the equator of Earth, and both pointing north. 05:00: Therefore, you can determine just by living on Earth's surface that Earth's surface is a curved space.
	2015-07-02: Can a Circle Be a Straight Line? 07:17: So is the three dimensional space around Earth curved? 08:12: ... in order to discuss the calendar, the seasons, and their connection to Earth's ... 09:18: ... is well understood, but since magnetic pole reversal wouldn't affect Earth's orbit or the tilt, any effects on the seasons would be ... 09:36: Time also runs at different rates at different locations on Earth that have different elevation. 09:40: ... time systems, or for instance, when you measure the rate at which the Earth slows its ... 07:17: So is the three dimensional space around Earth curved? 09:40: ... time systems, or for instance, when you measure the rate at which the Earth slows its ... 08:12: ... in order to discuss the calendar, the seasons, and their connection to Earth's ... 09:18: ... is well understood, but since magnetic pole reversal wouldn't affect Earth's orbit or the tilt, any effects on the seasons would be ... 08:12: ... in order to discuss the calendar, the seasons, and their connection to Earth's orbit. ... 09:18: ... is well understood, but since magnetic pole reversal wouldn't affect Earth's orbit or the tilt, any effects on the seasons would be ...
	2015-06-24: The Calendar, Australia & White Christmas 00:16: ... Earth's equator is tilted from the plane of its orbit by approximately 23 and ... 00:33: Now, from one spring equinox to the next spring equinox, Earth does not actually move a full 360 degrees around the sun. 00:48: The reason for this discrepancy is that the spinning Earth is basically a giant gyroscope. 00:53: See, Earth bulges slightly at the equator due to centrifugal effects from its own spin. 00:57: Since Earth's axis is tilted, one half of that bulge is a little closer to the sun than the other half at any given moment. 01:04: So the gravitational pull of the sun is slightly stronger on the slightly closer half, causing a net torque on the Earth like this. 01:29: ... the fact is that Earth's axis precesses in the opposite sense of Earth's orbit around the sun, so ... 02:22: But it doesn't track Earth's 360-degree orbit in space the way you might think. 02:26: Instead, it's locked to the solar year, to the seasons, so that it backtracks along Earth's orbit right along with the equinoxes and the solstices. 02:59: So the location of Earth on successive New Year's Eves backtracks along the orbit. 03:08: So every four years, we add February 29 to re-sync with Earth's orbit and undo that backtracking. 03:13: But the calendar isn't trying to sync to Earth's orbit. 03:24: We also need a little bit of extra slippage, because the annual discrepancy between the calendar and Earth's orbit also isn't precisely six hours. 04:17: If you look on time scales of tens of thousands or hundreds of thousands of years, Earth's orbit is a lot crazier than you would expect. 04:40: ... Earth is also slowly spinning down due to its interactions with the moon, so ... 05:27: If we're a space-faring species by then, then locking time exclusively to Earth's seasons might be weird. 05:58: Also, if you'd like to see an episode on what Earth's orbit and rotation really look like in space and why, let us know that, too. 00:53: See, Earth bulges slightly at the equator due to centrifugal effects from its own spin. 00:16: ... Earth's equator is tilted from the plane of its orbit by approximately 23 and ... 00:57: Since Earth's axis is tilted, one half of that bulge is a little closer to the sun than the other half at any given moment. 01:29: ... the fact is that Earth's axis precesses in the opposite sense of Earth's orbit around the sun, so ... 02:22: But it doesn't track Earth's 360-degree orbit in space the way you might think. 02:26: Instead, it's locked to the solar year, to the seasons, so that it backtracks along Earth's orbit right along with the equinoxes and the solstices. 03:08: So every four years, we add February 29 to re-sync with Earth's orbit and undo that backtracking. 03:13: But the calendar isn't trying to sync to Earth's orbit. 03:24: We also need a little bit of extra slippage, because the annual discrepancy between the calendar and Earth's orbit also isn't precisely six hours. 04:17: If you look on time scales of tens of thousands or hundreds of thousands of years, Earth's orbit is a lot crazier than you would expect. 05:27: If we're a space-faring species by then, then locking time exclusively to Earth's seasons might be weird. 05:58: Also, if you'd like to see an episode on what Earth's orbit and rotation really look like in space and why, let us know that, too. 02:22: But it doesn't track Earth's 360-degree orbit in space the way you might think. 00:57: Since Earth's axis is tilted, one half of that bulge is a little closer to the sun than the other half at any given moment. 01:29: ... the fact is that Earth's axis precesses in the opposite sense of Earth's orbit around the sun, so that ... 00:16: ... Earth's equator is tilted from the plane of its orbit by approximately 23 and 1/2 ... 01:29: ... the fact is that Earth's axis precesses in the opposite sense of Earth's orbit around the sun, so that the equinoxes and solstices backtrack along ... 02:26: Instead, it's locked to the solar year, to the seasons, so that it backtracks along Earth's orbit right along with the equinoxes and the solstices. 03:08: So every four years, we add February 29 to re-sync with Earth's orbit and undo that backtracking. 03:13: But the calendar isn't trying to sync to Earth's orbit. 03:24: We also need a little bit of extra slippage, because the annual discrepancy between the calendar and Earth's orbit also isn't precisely six hours. 04:17: If you look on time scales of tens of thousands or hundreds of thousands of years, Earth's orbit is a lot crazier than you would expect. 05:58: Also, if you'd like to see an episode on what Earth's orbit and rotation really look like in space and why, let us know that, too. 05:27: If we're a space-faring species by then, then locking time exclusively to Earth's seasons might be weird.
	2015-06-17: How to Signal Aliens 00:58: ... with the total area equivalent to a large city pointed right at Earth full time, our leakage would be hard to detect, let alone ... 04:59: ... billboard transits could only be seen within a few light years of earth or maybe a couple thousand if the Kerbal Kepler instrument is really ... 06:31: Several of you asked whether Earth is actually expanding outward, and that's not what I meant at all. 06:35: ... I meant to get across is that, since Earth's surface obviously is not accelerating outward in the ordinary sense of ... 07:17: ... all asked how two frames of reference falling on opposite sides of Earth can both the inertial when they're clearly accelerating with respect to ... 06:35: ... I meant to get across is that, since Earth's surface obviously is not accelerating outward in the ordinary sense of ...
	2015-06-03: Is Gravity An Illusion? 00:18: ... to Isaac Newton, the ground can be considered at rest, Earth applies a gravitational force to the apple, and that force causes the ... 02:23: ... to the tracks pretty much is inertial-- at least if you disregard Earth's rotation, because relative to that frame, you don't accelerate at ... 03:51: ... fake gravitational field with the actual gravitational field of the Earth, which points down, it looks like there's a net gravitational field ... 04:43: ... that with Earth's real gravitational field and it's as though the total gravity inside the ... 05:05: ... on the surface of some other planet with slightly bigger gravity than Earth and tilted upward by about 30 ... 05:39: ... asked, hold on, what if the so-called "real" downward gravity from Earth is also fake, a side effect generated because Earth's surface is really ... 05:52: ... are the standard for measuring true acceleration, so you can only say Earth is really accelerating upward if you can identify an inertial frame ... 06:35: ... just happens to exactly cancel the real downward gravitational field of Earth by ... 07:05: But freely-falling frames here on Earth also pass that test if your so-called gravity is fictitious. 07:48: So why are you insisting that the downward jolt we experience every day on Earth has a physical origin? 07:59: Now Newton says, nice try, Einstein, but you forgot something-- Earth is round. 08:11: First, two objects in a falling box are falling toward Earth on not-quite-parallel radial spokes. 10:42: Earth analogs in Earth-like orbits around Sun-like stars are not going to be visible. 00:18: ... to Isaac Newton, the ground can be considered at rest, Earth applies a gravitational force to the apple, and that force causes the apple to ... 10:25: Primarily, JWST is an infrared telescope that will see exoplanets because, contrary to Earthenfist's comment, planets do glow, in the infrared. 10:42: Earth analogs in Earth-like orbits around Sun-like stars are not going to be visible. 02:23: ... to the tracks pretty much is inertial-- at least if you disregard Earth's rotation, because relative to that frame, you don't accelerate at ... 04:43: ... that with Earth's real gravitational field and it's as though the total gravity inside the ... 05:39: ... gravity from Earth is also fake, a side effect generated because Earth's surface is really accelerating ... 05:52: ... upward if you can identify an inertial frame relative to which Earth's surface accelerates upward, and there's obviously no inertial frame like ... 04:43: ... that with Earth's real gravitational field and it's as though the total gravity inside the car ... 02:23: ... to the tracks pretty much is inertial-- at least if you disregard Earth's rotation, because relative to that frame, you don't accelerate at ... 05:39: ... gravity from Earth is also fake, a side effect generated because Earth's surface is really accelerating ... 05:52: ... upward if you can identify an inertial frame relative to which Earth's surface accelerates upward, and there's obviously no inertial frame like that, ...
	2015-05-27: Habitable Exoplanets Debunked! 00:02: Every few months, the press describes some recently discovered exoplanet as the closest thing yet to Earth's twin. 00:08: But how much like Earth are these planets really? 00:14: [MUSIC PLAYING] Lots of headlines have touted the discovery of potentially habitable worlds, some of which might be Earth twins. 02:49: Turns out Kepler 186F is about 10% larger in radius than Earth in an orbit around the size of Mercury around a fairly dim red dwarf star. 03:00: ... maybe it's nothing like Krypton, because at 500 light years from Earth, Kepler 186F is just too far away to determine its mass or anything about ... 05:13: To be in the habitable zone, a planet has to be small enough to be rocky like Earth instead of gaseous like Jupiter. 05:46: So for the foreseeable future, pinning down the actual habitability of true Earth analogs isn't happening. 06:04: I just think it's also important to understand that despite what you read, we don't actually have the means to identify Earth 2.0 yet. 06:16: ... if headlines didn't make people think we'd already identified Earth 2.0, there might be more public outcry to make these missions ... 06:28: ... about habitable exoplanets be shooting the actual identification of Earth's twin in the ... 06:50: If everyone on Earth picked up a hammer at the same time, by how much would Earth's mass increase due to the excess gravitational potential energy? 06:59: Earth's mass would stay exactly the same. 07:01: ... muscles and thus was already being weighed as part of the mass of the Earth. ... 07:17: Energy would have been injected into the system, and Earth's mass would negligibly increase. 06:04: I just think it's also important to understand that despite what you read, we don't actually have the means to identify Earth 2.0 yet. 06:16: ... if headlines didn't make people think we'd already identified Earth 2.0, there might be more public outcry to make these missions ... 05:46: So for the foreseeable future, pinning down the actual habitability of true Earth analogs isn't happening. 03:00: ... maybe it's nothing like Krypton, because at 500 light years from Earth, Kepler 186F is just too far away to determine its mass or anything about its ... 06:50: If everyone on Earth picked up a hammer at the same time, by how much would Earth's mass increase due to the excess gravitational potential energy? 00:14: [MUSIC PLAYING] Lots of headlines have touted the discovery of potentially habitable worlds, some of which might be Earth twins. 02:05: We don't know anything about the atmospheres of any of the so-called Earth-like habitable worlds that get reported in the press. 03:26: ... could be Earth-like, or it could be wispy and barely there, like on Mars, or a carbon dioxide ... 05:34: ... that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 02:05: We don't know anything about the atmospheres of any of the so-called Earth-like habitable worlds that get reported in the press. 03:26: ... could be Earth-like, or it could be wispy and barely there, like on Mars, or a carbon dioxide ... 05:34: ... that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 02:05: We don't know anything about the atmospheres of any of the so-called Earth-like habitable worlds that get reported in the press. 05:34: ... that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 00:02: Every few months, the press describes some recently discovered exoplanet as the closest thing yet to Earth's twin. 06:28: ... about habitable exoplanets be shooting the actual identification of Earth's twin in the ... 06:50: If everyone on Earth picked up a hammer at the same time, by how much would Earth's mass increase due to the excess gravitational potential energy? 06:59: Earth's mass would stay exactly the same. 07:17: Energy would have been injected into the system, and Earth's mass would negligibly increase. 06:50: If everyone on Earth picked up a hammer at the same time, by how much would Earth's mass increase due to the excess gravitational potential energy? 06:59: Earth's mass would stay exactly the same. 07:17: Energy would have been injected into the system, and Earth's mass would negligibly increase. 06:50: If everyone on Earth picked up a hammer at the same time, by how much would Earth's mass increase due to the excess gravitational potential energy? 00:02: Every few months, the press describes some recently discovered exoplanet as the closest thing yet to Earth's twin. 06:28: ... about habitable exoplanets be shooting the actual identification of Earth's twin in the ... 02:18: In April 2014, this planet got a lot of press as the first confirmed Earth-sized exoplanet in the habitable zone of its host star. 03:46: You can measure the atmosphere of an exoplanet, but not if that exoplanet is an Earth-sized rocky body in a star's habitable zone. 05:34: ... or TPF, a space telescope that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 02:18: In April 2014, this planet got a lot of press as the first confirmed Earth-sized exoplanet in the habitable zone of its host star. 03:46: You can measure the atmosphere of an exoplanet, but not if that exoplanet is an Earth-sized rocky body in a star's habitable zone. 05:34: ... or TPF, a space telescope that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 02:18: In April 2014, this planet got a lot of press as the first confirmed Earth-sized exoplanet in the habitable zone of its host star. 05:34: ... or TPF, a space telescope that could have analyzed the atmospheres of Earth-sized planets in Earth-like orbits around Sun-like like ... 03:46: You can measure the atmosphere of an exoplanet, but not if that exoplanet is an Earth-sized rocky body in a star's habitable zone.
	2015-05-20: The Real Meaning of E=mc² 03:57: Don't worry, Earth's orbit is going to be fine. 05:37: ... potential energy drops when you get closer to the surface of Earth, which is also attracting ... 08:45: Suppose that every person on Earth simultaneously picks up a hammer from the ground. 03:57: Don't worry, Earth's orbit is going to be fine.
	2015-05-13: 9 NASA Technologies Shaping YOUR Future 00:56: Next problem-- the space station orbits Earth so fast that each new sunrise happens every 90 minutes. 03:58: Now a really big problem-- astronauts in micro gravity lose bone density 10 times faster than people on earth with osteoporosis do. 03:07: And if you can dampen the vibrations from a firing rocket, how about dampening the vibrations from earthquakes? 03:23: So that's right, the NASA spinoff in this case is earthquake proof buildings. 03:07: And if you can dampen the vibrations from a firing rocket, how about dampening the vibrations from earthquakes? 03:23: So that's right, the NASA spinoff in this case is earthquake proof buildings. 03:07: And if you can dampen the vibrations from a firing rocket, how about dampening the vibrations from earthquakes?
	2015-05-06: Should the First Mars Mission Be All Women? 00:47: Let's start with the physiological arguments for all-female missions beyond Earth's moon. 01:02: ... we can't have these pioneers falling apart 200 million miles from Earth. ... 02:06: And women faint more easily from standing up too fast once they get back to Earth, which may not be as big a deal in Martian gravity-- still unclear. 04:55: For whatever reason, the calorie requirements in space and on Earth are basically the same. 05:35: ... you need to work out how much fuel it would take to get that food from Earth orbit to Mars orbit and back, and then estimate the cost of getting the ... 07:56: I agree it has slow RPMs and low Coriolis effects, but it only has 0.7 earth Gs, which might be intentional. 05:35: ... you need to work out how much fuel it would take to get that food from Earth orbit to Mars orbit and back, and then estimate the cost of getting the food ... 00:47: Let's start with the physiological arguments for all-female missions beyond Earth's moon. 05:35: ... and then estimate the cost of getting the food plus all that fuel off of Earth's surface to begin ... 00:47: Let's start with the physiological arguments for all-female missions beyond Earth's moon. 05:35: ... and then estimate the cost of getting the food plus all that fuel off of Earth's surface to begin ...
	2015-04-29: What's the Most Realistic Artificial Gravity in Sci-Fi? 00:58: There's simply no known way to produce the equivalent of 1 Earth g on stacked, flat surfaces, like decks of a ship, in any localized region of space. 02:01: ... you is to prevent that outward fall, kind of like how the ground here on Earth pushes up on your feet to keep you from falling inward toward Earth's ... 02:10: ... a radially outward directed "gravity." Now, if you were out in space, Earth's real gravity, which also pulls you down, wouldn't be in the ... 02:38: ... as the force from the ground currently on your feet and thus simulate Earth's 1 g of surface ... 03:17: ... produce 1 Earth g of effective gravity at its surface or 10 meters per second squared, ... 05:17: ... "Ringworld." The ring habitat in that novel has the same radius as Earth's entire orbit around the sun, around 93 million ... 05:31: ... Ringworld's rotational velocity would be small enough that, just like on Earth, Coriolis effects would only be noticeable at very high ... 05:51: To sustain 1 g, the ring would need to complete the equivalent of one Earth orbit around the sun in only nine days. 06:20: ... the video game "Halo." At a radius of 5,000 kilometers or about 80% of Earth's radius, a halo insulation would need to rotate 19 times a day to produce ... 05:31: ... Ringworld's rotational velocity would be small enough that, just like on Earth, Coriolis effects would only be noticeable at very high ... 05:51: To sustain 1 g, the ring would need to complete the equivalent of one Earth orbit around the sun in only nine days. 02:01: ... you is to prevent that outward fall, kind of like how the ground here on Earth pushes up on your feet to keep you from falling inward toward Earth's ... 02:10: ... a radially outward directed "gravity." Now, if you were out in space, Earth's real gravity, which also pulls you down, wouldn't be in the ... 02:38: ... as the force from the ground currently on your feet and thus simulate Earth's 1 g of surface ... 05:17: ... "Ringworld." The ring habitat in that novel has the same radius as Earth's entire orbit around the sun, around 93 million ... 06:20: ... the video game "Halo." At a radius of 5,000 kilometers or about 80% of Earth's radius, a halo insulation would need to rotate 19 times a day to produce ... 02:38: ... as the force from the ground currently on your feet and thus simulate Earth's 1 g of surface ... 02:01: ... on Earth pushes up on your feet to keep you from falling inward toward Earth's center. ... 05:17: ... "Ringworld." The ring habitat in that novel has the same radius as Earth's entire orbit around the sun, around 93 million ... 06:20: ... the video game "Halo." At a radius of 5,000 kilometers or about 80% of Earth's radius, a halo insulation would need to rotate 19 times a day to produce 1 g or ... 02:10: ... a radially outward directed "gravity." Now, if you were out in space, Earth's real gravity, which also pulls you down, wouldn't be in the ...
	2015-04-15: Could NASA Start the Zombie Apocalypse? 01:22: In 2006, researchers sent some salmonella on the space shuttle, brought it back down to Earth, and then infected mice with it. 03:46: And dealing with that fact is one of the biggest challenges in establishing a larger human presence in Earth orbit and beyond. 05:37: ... nothing to push against-- the same way you're pushing against water on Earth. ... 03:46: And dealing with that fact is one of the biggest challenges in establishing a larger human presence in Earth orbit and beyond.
	2015-04-08: Could You Fart Your Way to the Moon? 02:17: Clearly, the resulting thrust is tiny enough not to move you noticeably here on Earth. 02:48: In truth, even starting out from low Earth order, you'd be short of Earth's escape velocity by a factor of about a billion. 07:09: Chronoflect asked whether Termina's moon could actually rip apart in the three day window of the game if it were the density of Earth's moon. 02:48: In truth, even starting out from low Earth order, you'd be short of Earth's escape velocity by a factor of about a billion. 02:37: In fact, with just a single day's worth of flatus, you could travel the entire Earth-Moon distance in only 300,000 years. 02:48: In truth, even starting out from low Earth order, you'd be short of Earth's escape velocity by a factor of about a billion. 07:09: Chronoflect asked whether Termina's moon could actually rip apart in the three day window of the game if it were the density of Earth's moon. 02:48: In truth, even starting out from low Earth order, you'd be short of Earth's escape velocity by a factor of about a billion. 07:09: Chronoflect asked whether Termina's moon could actually rip apart in the three day window of the game if it were the density of Earth's moon.
	2015-04-01: Is the Moon in Majora’s Mask a Black Hole? 01:52: ... reasons I'll explain shortly, anything with the density of Earth's moon would be ripped apart if it got within 12,000 kilometers of Earth's ... 03:25: For instance, the tidal force from Earth's moon on you right now it's about 10 million times smaller than Earth's pull on you. 03:34: Of course, if you bring the moon closer, on Earth or on Termina, the tidal force from the moon will increase. 03:41: On Earth, absolutely not. 04:00: ... Termina's moon really were only as dense as Earth's moon, its tidal force when hovering just above the planet's surface ... 04:22: ... be-- wait for it-- between a billion and 100 trillion times denser than Earth's moon, depending on whether you think the tidal force is just whipping ... 04:40: After all, the planet also exerts a tidal force on the moon, which would rip Earth's moon apart if it got too close to us. 04:48: So a trillion times the density of Earth's moon-- that's ridiculous. 05:18: Termina's moon, even at these densities, only weighs about half as much of Earth's moon. 06:39: For example, gravity would be billions of times stronger on Termina's moon than on Earth. 09:00: The Earth has superimposed an individual motion through the galaxy. 09:17: Finally, Paul Ansel emailed me a calculation working out how much energy it would take to break Earth apart atom by atom. 03:41: On Earth, absolutely not. 04:16: There's no way it would cause earthquakes, and it certainly wouldn't cause rocks to levitate. 01:52: ... reasons I'll explain shortly, anything with the density of Earth's moon would be ripped apart if it got within 12,000 kilometers of Earth's ... 03:25: For instance, the tidal force from Earth's moon on you right now it's about 10 million times smaller than Earth's pull on you. 04:00: ... Termina's moon really were only as dense as Earth's moon, its tidal force when hovering just above the planet's surface ... 04:22: ... be-- wait for it-- between a billion and 100 trillion times denser than Earth's moon, depending on whether you think the tidal force is just whipping ... 04:40: After all, the planet also exerts a tidal force on the moon, which would rip Earth's moon apart if it got too close to us. 04:48: So a trillion times the density of Earth's moon-- that's ridiculous. 05:18: Termina's moon, even at these densities, only weighs about half as much of Earth's moon. 01:52: ... reasons I'll explain shortly, anything with the density of Earth's moon would be ripped apart if it got within 12,000 kilometers of Earth's ... 03:25: For instance, the tidal force from Earth's moon on you right now it's about 10 million times smaller than Earth's pull on you. 04:00: ... Termina's moon really were only as dense as Earth's moon, its tidal force when hovering just above the planet's surface would be ... 04:22: ... be-- wait for it-- between a billion and 100 trillion times denser than Earth's moon, depending on whether you think the tidal force is just whipping the ... 04:40: After all, the planet also exerts a tidal force on the moon, which would rip Earth's moon apart if it got too close to us. 04:48: So a trillion times the density of Earth's moon-- that's ridiculous. 05:18: Termina's moon, even at these densities, only weighs about half as much of Earth's moon. 04:22: ... be-- wait for it-- between a billion and 100 trillion times denser than Earth's moon, depending on whether you think the tidal force is just whipping the rocks upward ... 03:25: For instance, the tidal force from Earth's moon on you right now it's about 10 million times smaller than Earth's pull on you. 01:52: ... Earth's moon would be ripped apart if it got within 12,000 kilometers of Earth's surface. ...
	2015-03-18: Can A Starfox Barrel Roll Work In Space? 07:00: ... of "Space Time." Last week, we talked about what might destroy planet Earth, and you guys have a lot to ... 07:09: A lot of you ended up raising many of the same alternate Earth destruction scenarios. 08:04: And that, if some of that matter appeared on Earth, it would trigger a chain reaction wherein every nucleus on Earth would revert into that state. 08:18: Lots of you asked whether Earth could suffer a collision when the Andromeda and Milky Way galaxies merge in about 4 billion years. 08:42: Likewise, people ask whether rogue planets or rogue black holes, streaking through the Milky Way, could come in and collide with Earth. 09:05: But even if Ceres is an asteroid, it's only about three and a half times as massive as 4 Vesta, still not enough energy to destroy the Earth. 09:13: ... just to overcome the gravitational attraction between all the matter on Earth, but to split apart every interatomic bond as ... 09:25: ... need to know how much energy there is in interatomic bonds, per atom on Earth, and multiply that by an estimate of the number of atoms on ... 07:09: A lot of you ended up raising many of the same alternate Earth destruction scenarios.
	2015-03-11: What Will Destroy Planet Earth? 00:00: Lots of unpleasant things from nuclear war to asteroid impacts could destroy life on Earth. 00:05: But what about Earth itself? 00:24: Now in the case of Earth, the main glue is the collective gravity of almost six septillion kilograms of mass. 00:34: About as much solar energy as a whole Earth receives over 40 million years. 00:39: Now if you just want to split Earth in half, you get a bit of a discount-- only 16 million years worth of sunshine. 00:45: So realistically, could anything deliver that much energy to Earth and end the planet as we know it? 01:22: Is there even enough mineable uranium on Earth for that? 01:36: So can we nuke the Earth to a barren wasteland? 02:07: ... destroy Earth, 4-Vesta would have to hurtle toward it at 700 kilometers per second-- or ... 02:18: In fact, a head-on collision between Earth and any solar system object deflected into our path will top out at a mere 70 to 80 kilometers per second. 02:27: Now with those speeds, an object could only carry enough energy to destroy Earth if it had a huge mass, which asteroids don't. 02:40: Mars orbit outside Earth's orbit, so how could they collide? 02:44: Well, Earth and Mars' field gravitational pulls not just from the sun, but also from the other plants-- and from big asteroids too. 03:19: But in 1%, the inner planet orbits stretch out after about three billion years and Earth starts doing drive-bys of Venus and Mars. 03:26: In one simulation, about four billion years from now, Earth and Mars actually collide with enough energy to do serious structural damage. 03:52: For instance, if Earth enters the sun. 03:56: ... into a red giant-- inflating until it becomes slightly larger than Earth's entire current ... 04:05: Now if Earth stays where it is now, during that growth spurt, we get swallowed up. 04:16: So the Earth is toast, right? 04:27: In the process, the sun will lose a lot of mass and a lot of gravitational pull, causing Earth's orbit to actually grow. 04:34: For decades, whether Earth will be swallowed by the sun or not has been too close to call. 04:40: But the best recent simulations show that Earth will end up just inside the sun and fry. 04:53: ... is a shame, because it means earth is unlikely to face one final destruction scenario that we're going to ... 05:22: Note that the Earth and you and I stay in one piece because the space inside galaxies is not stretching-- at least not yet. 06:25: Being ripped to pieces like Braveheart would be totally sweet, but Earth will probably burn up like Joan of Arc-- which is still going out in style. 06:33: Now, how would you prefer to have Earth meet its maker? 06:35: ... me know in the comments along with any other viable scenarios for Earth destruction that I might have overlooked-- and no, the Death Star is not ... 02:07: ... destroy Earth, 4-Vesta would have to hurtle toward it at 700 kilometers per second-- or fast ... 06:35: ... me know in the comments along with any other viable scenarios for Earth destruction that I might have overlooked-- and no, the Death Star is not a viable ... 03:52: For instance, if Earth enters the sun. 06:33: Now, how would you prefer to have Earth meet its maker? 00:34: About as much solar energy as a whole Earth receives over 40 million years. 03:19: But in 1%, the inner planet orbits stretch out after about three billion years and Earth starts doing drive-bys of Venus and Mars. 04:05: Now if Earth stays where it is now, during that growth spurt, we get swallowed up. 04:09: See, another paper in the description works out that an Earth-like planet in a solar atmosphere would vaporize after a few million years. 02:40: Mars orbit outside Earth's orbit, so how could they collide? 03:56: ... into a red giant-- inflating until it becomes slightly larger than Earth's entire current ... 04:27: In the process, the sun will lose a lot of mass and a lot of gravitational pull, causing Earth's orbit to actually grow. 03:56: ... into a red giant-- inflating until it becomes slightly larger than Earth's entire current ... 02:40: Mars orbit outside Earth's orbit, so how could they collide? 04:27: In the process, the sun will lose a lot of mass and a lot of gravitational pull, causing Earth's orbit to actually grow.
	2015-03-04: Should We Colonize Venus Instead of Mars? 01:11: For starters, Venus is closer to Earth. 02:06: Venus has about 0.9 Earth g's-- pretty close-- while Mars has less than 0.4. 02:15: In Earth orbit, astronauts lose bone mass at about 10 times the rate of someone with advanced osteoporosis. 03:31: It's over 90 Earth's atmospheres. 03:33: ... on the Venutian surface would be like diving one kilometer underwater on Earth-- far beyond the crush depth of most military ... 04:21: ... still super hot, but firefighting equipment on Earth can withstand proximity to forest fires with temperatures that reach ... 04:29: The pressure at that altitude also dropped to almost exactly one Earth atmosphere. 04:45: ... like balloons filled with helium or maybe filled even with just regular Earth ... 04:29: The pressure at that altitude also dropped to almost exactly one Earth atmosphere. 02:15: In Earth orbit, astronauts lose bone mass at about 10 times the rate of someone with advanced osteoporosis. 04:54: ... atmosphere of Venus might be the closest thing in the solar system to an Earth-like ... 03:31: It's over 90 Earth's atmospheres.
	2015-02-25: How Do You Measure the Size of the Universe? 02:01: Galaxy clusters aren't expanding and neither are individual galaxies, or the Earth, or people, or trees. 03:07: ... light from a distant galaxy would be the same color when it arrived on Earth as it was when it first set out, blue on departure, blue on ...
	2015-02-18: Is It Irrational to Believe in Aliens? 01:37: Because the only place we've ever seen so much as an amoeba is Earth. 02:53: ... habitable worlds, it would start to look like a cosmic conspiracy, like Earth and humanity are absurdly ... 07:01: D. Moritz found that Sonica Hedgehog lives on a planet with about 5.6 Earth gees, Closer to a planet.
	2015-02-11: What Planet Is Super Mario World? 00:26: Now on Earth, an object rising straight upward will lose 9.8 meters per second of its speed each second. 00:58: ... is called the acceleration due to gravity, or the surface gravity of Earth. ... 02:40: If we set h to 3.5 meters and t to 0.3 seconds, we get a final g value of around 78 meters per second per second, or almost 8 Earth g's. 02:51: That means "Super Mario World" has about eight times the surface gravity of Earth. 03:03: Their results show some variation, but all give surface gravities of between 5 and 10 Earth g's, which is consistent with my crude calculation. 03:22: And the bottom line is that g is bigger on Super Mario World than on Earth, so that weaker gravity is not in fact the key to Mario's jumping prowess. 03:33: Remember, gravity is eight times stronger on Super Mario World than it is on Earth, yet Mario jumps much higher than we can on Earth. 03:43: If Mario were on Earth, he would have a takeout speed of over 50 miles an hour and be able to jump about 28 meters, or over 90 feet. 04:00: On a planet with eight times Earth's surface gravity, your blood is eight times as heavy. 04:24: You can compute it with the following formula, using Earth's mass and radius as a reference. 04:28: What you find is that all the major rocky bodies-- that means the moon, Mars, Venus, Mercury-- all of them have smaller g values than Earth does. 04:36: ... for comparison, the g values they would have are all within 15% or so of Earth. ... 04:46: Even on Jupiter, g is only 2 and 1/2 times or so Earth's value. 04:59: ... the surface gravity, and you find those with values that are many times Earth g's are thought to be gas ... 04:00: On a planet with eight times Earth's surface gravity, your blood is eight times as heavy. 04:24: You can compute it with the following formula, using Earth's mass and radius as a reference. 04:46: Even on Jupiter, g is only 2 and 1/2 times or so Earth's value. 04:24: You can compute it with the following formula, using Earth's mass and radius as a reference. 04:00: On a planet with eight times Earth's surface gravity, your blood is eight times as heavy.

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