
20221214: How Can Matter Be BOTH Liquid AND Gas?
 02:11: ... there’s the socalled triple point, where all three states can exist simultaneously, From the triple point, ...
 02:48: This end point of the liquidgas boundary is called the critical point, and it’s very real.
 06:21: That ice was presumably created below the 194.7 Kelvin freezing point of CO2 at atmospheric pressure.
 07:27: ... but look at the phase diagram: At higher pressures the boiling point of CO2 increases, which means all this pressure makes it harder and ...
 08:27: At that point, microscopic droplets of remaining liquid are free to flow and swirl through the gas phase to diffuse.
 08:36: We’re now at the critical point.
 13:25: ... CO2 within a few kilometers of the surface well beyond the supercritical point. ...
 17:05: Amorphant points out that we didn’t mention magnetic monopoles as an example of quasiparticles.


20221208: How Are Quasiparticles Different From Particles?
 01:44: ... thermal vibrations or in the case of solar cells by a photon, at which point the electron is free to move from atom to atom  for example if pulled ...


20221123: How To See Black Holes By Catching Neutrinos
 05:23: ... around immediately, leading to a bubble of Cherenkov near their creation point. ...
 10:10: Now a blazar is an AGN where a magneticallychanneled jet happens to be pointing more or less directly at us.


20221116: Are there Undiscovered Elements Beyond The Periodic Table?
 16:37: ... that the future emergence of new civilizations has to be cut off at some point, or else humanity is too surprisingly early to the ...
 18:57: ... Cleveland points out that life may have had the potential to arise many times on early, ...


20221109: What If Humanity Is Among The First Spacefaring Civilizations?
 00:48: From this point of view, we’re living pretty much at the beginning of the universe.
 09:08: Each point represents a choice of hardstepnumber and maximum planet lifetime, and the color of that point tells you our birth rank.
 11:01: The model claims that at some point in the future, all habitable planets will be occupied by rapidly expanding alien civilizations.
 17:08: ... Yavor Tch and zomgthisisawesomelol point out that Einstein was referring to wavefunction collapse when he said ...


20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 06:12: Apparently Feynman thought it was pointless because standard quantum mechanics was clearly correct.
 07:48: John Bell himself pointed out that hidden variables could still be a thing, even if the Bell test said otherwise.
 13:53: Because science only moves forward when we try to push its theories to the breaking point.
 16:04: Antoine Micard brought up an important point: how do the spacecraft send their messages back home?
 18:21: The idea here was to give you a taste of its contents, and perhaps a starting point for further investigation.


20221019: The Equation That Explains (Nearly) Everything!
 04:36: ... that is exactly what the Standard Model Lagrangian is. I’m obliged to point out that this is technically not a Lagrangian, but rather a Lagrangian ...
 11:28: ... components. And it can also stand for hot coffee, because this is the point in reading the Lagrangian where most people need a coffee ...


20221012: The REAL Possibility of Mapping Alien Planets!
 00:03: ... A train of spacecraft sailing the sun’s light to a magical point out there in space where the Sun’s own gravity turns it into ...
 04:36: ... lenses are designed to bring light from the same point to a single focus point, allowing an image to be formed. ...
 10:07: ... focal range is indeed a range. While a regular lens creates a focal point, the Sun’s gravitational field creates a focal line, starting at 550 ...
 12:52: ... to distinguish from their colours. And if we spot bright points of light on the planet’s night side  aka cities  that ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 12:55: ... hints at a connection between the other fundamental constants  perhaps pointing to an underlying common mechanism that set the values for the ...


20220921: 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.
 07:34: ... day you’ll get another email with a download link to your data, at which point the real work can begin: analyzing the data and trying to bring to ...
 09:14: JWST pointed at it for 12 and a half hours across different filters to produce the deepest infrared image of any spot on the sky ever taken.
 09:54: Those pointy things are diffraction spikes, caused by interactions of incoming light with the hexagonal aperture of the scope.
 11:26: ... 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 shows us things ...
 12:36: Lassi Tiihonen and John Rizzo raise an excellent point: our strong force video didn’t really explain how atomic nuclei stick together.
 15:31: ... points out that we forgot to mention one of the important Higgs experiments  ...
 16:13: nyrdybyrd points out that the info from this Higgs episode is an influential argument for a badass new particle collider.
 16:23: This is a good point.


20220914: Could the Higgs Boson Lead Us to Dark Matter?
 05:21: Those particles are sometimes detected directly when they smash into one of the many detectors surrounding the collision point.


20220824: What Makes The Strong Force Strong?
 07:25: At a certain point the tube will snap  but only when exactly enough energy has been built up to create a new pair of quarks.
 07:55: ... enough energy, like in the very early universe or at impact point in a large particle collider, space gets sort of saturated so that new ...


20220817: What If Dark Energy is a New Quantum Field?
 05:18: ... if evidence is pointing to omega=1, and we have a plausible physical explanation for omega=1, ...
 12:31: ... not true if omega is less than 1  that’s the big rip, in which all points in space eventually become infinitely far apart. Fortunately, that seems ...


20220803: What Happens Inside a Proton?
 08:58: ... by adding up the probabilities of all possible paths between those points. Actually, it also includes the impossible paths, but no time to ...
 09:50: ... of spacetime technically contains an infinite number of points and no computer can hold an infinite amount of memory. ...
 10:43: ... where the probability of a particle landing at a certain point on the screen depends on whether the phases of different ...
 11:28: ... time step results a complexvalued phase shift at each spatial point. Those complex numbers are fine in the Feynman ...
 12:15: ... our couple quarkgluon field looks like this: a lattice of points with connections. The points are the quark field and ...
 12:52: ... After all, spacetime isn’t really a discrete lattice of points. But it turns out that the things you want to ...
 15:29: ... booba points out an error in our definition of “absolute zero” temperature. We ...


20220727: How Many States Of Matter Are There?
 02:59: ... example, at temperatures and pressures above the critical point, the line between gas and liquid blurs and we have a supercritical fluid ...


20220720: What If We Live in a Superdeterministic Universe?
 07:40: ... a local realist theory, every point in space and time  every event  can only be influenced by a spacetime ...
 11:54: And that’s … impossible because if you trace the past lightcone of any two points in the observable universe back far enough they will overlap.
 16:32: ... Van Cantfort points out that a bigger problem than these conventions might be just the units ...
 17:03: ... that note, Dandelion Stitches points out that the problem with electric charge sign convention could be ...
 17:20: Dai Lixiuyuan and MrOvipare point out that we’d be able to tell what time "direction" the aliens use by their laws of thermodynamics.
 17:56: ... why the scenario I outlined was not the actual point of the video  rather, it was a nefarious trick to teach you about ...
 18:07: ... as Benjamin Heasly points out, aliens would surely give some tests we could run to not risk ...


20220630: Could We Decode Alien Physics?
 02:25: ... means a large charge difference builds up in the rod near your point of contact, and that causes electrons to jump from ...
 07:38: ... direction to that electron. To find that direction you just point the index finger of your right hand in the direction ...
 13:42: ... choice reveals something powerful. It points to the existence of an underlying symmetry of space ...
 16:39: ... novel shielding ideas that we could’t survey in this episode  the point was really to assess whether interstellar travel was a ...


20220615: Can Wormholes Solve The Black Hole Information Paradox?
 00:26: ... the latest attempt to solve the black hole information paradox are pointing to a bizarre picture in which each black hole behaves ...
 05:20: ... more and more radiation is produced, but then at some point the entropy starts to drop again because the information from ...
 07:24: ... probability of some quantum particle traveling between two points by adding up all ways the particle could make that ...
 09:36: ... They’re actually complex geometries, distances between some points are complexvalued rather than real valued. But for the ...


20220601: What If Physics IS NOT Describing Reality?
 04:56: ... “physical” answer. Consider quantum spin. From a physical point of view, think of it as a particle’s orientation  a spin axis ...
 05:38: ... say we prepare an electron’s spin to all point up relative to our apparatus. The spin contains one bit of ...
 05:53: ... what if we asked the electron spin a different question “are you pointing left or right?” We can do this by rotating the Stern Gerlach ...


20220525: The Evolution of the Modern Milky Way Galaxy
 15:22: ... few of you pointed out that even a system with lots of gas giants could have ...
 15:56: Some of you pointed out other possible explanations for the Fermi paradox and the specialness of Earth.
 18:10: ... to that comment to address the dark energy issue. He rightly points out that the Schwarzschild metric isn’t really valid in ...


20220518: What If the Galactic Habitable Zone LIMITS Intelligent Life?
 01:36: ... from the perspectives of science versus our own slightly biased point of ...
 04:32: ... So it sounds like the galaxy should be full of potential starting points for life, even if we assume that life can only form on ...


20220504: Space DOES NOT Expand Everywhere
 01:24: ... motion or “peculiar velocity” is small compared to the fact that distant points are moving apart  receding  and the further distant the faster the ...
 03:48: ... Pythagorus for 4D spacetime  the squared proper distance between two points is the sum of the squares of x, y & z, but here adding the dimension ...
 07:12: ... the universe becomes an expanding ring instead of a ,sphere, with grid points instead of gridlines. But then we can add the dimension of time into our ...
 07:58: ... gridlines to be pulled together on a sphere, then on the ring it causes points to be pulled together, and they maintain that separation as the ring ...
 09:16: ... expand. The grid lines diverge, but we can choose to regrid it at any point. What was once a millimeter might become a meter and the meter becomes a ...
 09:38: ... the universe of the present and define a grid of space  or a grid of points on our 1D ring universe. Then we rewind the universe and every single ...
 14:34: ... of you reasonably point out that it is potentially misleading to use terms like “observation” or ...


20220427: How the Higgs Mechanism Give Things Mass
 01:48: ... point in space can wiggle, twist, oscillate in different ...
 02:04: ... where you decide to center your xyz axes, or where you put the zero point of your angles in polar ...
 02:31: ... of this. The exact phase of the quantum wavefunction from one point in space to the next  local phase  doesn’t affect ...
 07:01: ... energy stored when the field value moves away from the zero point, trying to pull it back to the center. Graphing this, ...
 07:33: ... are just oscillations of the field strength across the lowest point, where the field strength is zero. But if there are no particles ...
 09:34: ... to still make sense if there are rotations from one point in space to the next. That means adding a new gauge field in the ...
 11:02: ... not be symmetric to the same rotations, because different points around this valley correspond to different physical states. ...
 12:59: ... field that shakes out shifts in our arbitrary choice of the zero point of ...


20220420: Does the Universe Create Itself?
 14:50: ... that the center of the universe and the location of the big bang are points in time in the past. So, they’re fair as long as you explain what you ...


20220330: Could The Universe Be Inside A Black Hole?
 01:01: In general relativity, that looks like a point of infinite density surrounded by an event horizon.
 01:30: ... singularity is the Big Bang, which we think of as a point in time at the beginning of the universe when all matter was compressed ...
 02:46: ... difference is that the black hole singularity seems to us to be a point of infinite density in space, while the big bang singularity is a time ...
 03:54: ... possible to define a geodesic at some point in space and time  say, the arc of a ball thrown through the air  and ...
 04:41: In fact, in general relativity, singularities are defined as the end points of geodesics.
 06:35: But there’s still an “outside” in which the white hole appears as a bright, localized point in space.


20220323: Where Is The Center of The Universe?
 02:01: But the Big Bang isn’t an explosion emanating from one point in space.
 02:20: In this picture the Big Bang isn’t something that happened at a single point in space, instead it happened everywhere at the same time.
 05:20: If I were to ask a denizen of the surface of the sphere to point to the center of the universe, they couldn’t do it.
 05:28: They can’t point “down” to the center of the sphere, because to them there is no down.
 05:43: Could there be an equivalent of “down” in that space that we are just too dimensionallychallenged to point to?
 06:06: But actually, we can sort of give a location for this expanding hypersphere  because at one point we were at that center.
 06:52: That means we really CAN point to the location of the Big Bang  by pointing to the past.
 06:59: And conveniently, you can point to the past  by pointing in any direction whatsoever.
 07:06: You can point at, say, the moon by ensuring that a line drawn from your outstretched finger intersects would intersect the moon.
 07:13: ... course your wouldn’t be pointing at the moon of the present  it would be the moon of the past, because ...
 07:27: Now imagine that 2D dweller points at a random direction.
 07:39: ... around the closed universe as the sphere shrinks, until eventually all points in the universe, including the pointed line, coincide with the ...
 07:49: It’s the same with our universe  point in any direction and you’re pointing at the Big Bang.
 07:55: And if the universe really is closed, you’re also pointing at the point where all space occupied the geometrical center of the hypersphere.
 08:27: ... you can still point at the Big Bang by pointing in a random direction, because the line ...
 08:48: No matter the geometry of our FLRW universe, all geodesics converge to a single point in the past, and end there.
 09:09: ... is literally no direction that you could point that would not intersect the Big Bang if traced backwards, and that’s ...
 09:31: OK, so maybe the location of the Big Bang isn’t at one point in this universe.
 09:36: But can we still say that the Big Bang happened at one point?
 09:40: ... mean, if all points converged onto the same point at the beginning  if all geodesics ...
 09:52: In the case of the closed universe that’s easier to imagine  rewind the growing sphere and it approaches a single point at t=0.
 10:03: The math of the FLWR metric and the Friedman equations tell us that as time approaches zero, the distance between any two points approaches zero.
 10:13: But at the same time there are infinite points.
 10:16: So did the universe start out pointlike at t=0 and then suddenly become infinite in size?
 10:23: Well the size of the universe at t=0 is zero times infinity … which is neither zero nor infinity  it’s the point where the math breaks.
 12:47: ... should point out that this doesn’t necessarily break the Cosmological principle ...


20220316: What If Charge is NOT Fundamental?
 01:47: At some point, Heisenberg turned his remarkable intellect to the newly discovered neutron.
 02:18: At this point we already knew of particles that had internal states.
 08:42: It may seem like the strong force led us astray  but actually it points to the answer.


20220308: Is the Proxima System Our Best Hope For Another Earth?
 09:12: One very important point is that Proxima B is probably tidally locked to its star.
 19:37: ... that is, we can see the difference in the phase angle between two points in ...


20220223: Are Cosmic Strings Cracks in the Universe?
 00:00: ... If the crystallization process starts from multiple nucleation points then there’ll be imperfections in the lattice structure where the ...
 00:58: ... property that the fabric of space can have. The field at any point can oscillate around that value, and those oscillations can ...
 04:51: ... a higher energy than it needed. It was momentarily stable at that point, just like a ball sitting at the top of a hill. But the slightest ...
 05:59: ... valley. That means we can ascribe an angle to every point in space defining the relative value of the two components ...
 07:33: ... defects may be possible. For example, a zerodimensional, pointlike topological defect would be a magnetic monopoles, which we ...
 12:19: ... these. Now if we do find a cosmic string, there’s one other point of confusion we’d need to settle. Is this a cosmic string, or is ...


20220216: Is The Wave Function The Building Block of Reality?
 01:24: ... in a superposition of dead and alive? Honestly, probably not. At some point between atom and cat the fuzziness of the atom’s wave function collapses ...
 08:55: ... like the other forces. All of the collapse models attempted to answer point 1, but only Diósi and Penrose’s model could answer 2: gravity can’t be ...
 14:52: ... also asks whether it’s possible to focus gravitational waves to a single point to create a black hole without mass. The answer is again yes. Just as ...
 16:00: ... slows the event down during the collapse. So this is a confusing point. ...
 16:15: ... we talk about approaching the black hole event horizon is not from the point of view of falling matter, but from the point of view of a distant ...


20220210: The Nature of Space and Time AMA
 00:03: ... the nature of space and the nature of time now i should start out by pointing out that no one knows what the nature of space and the nature of time ...


20220127: How Does Gravity Escape A Black Hole?
 01:01: ... theory, any object that reaches such a density has to collapse to a pointlike singularity of infinite density surrounded by this boundary of no return ...
 04:14: ... rubber at any one point in the sheet doesn’t know about the massive object  it’s being ...
 04:56: At some point it exceeds the swimming speed of any possible fish  that’s the event horizon.
 05:03: Any fish that passes that point will be carried to the singularity  the fall itself.
 10:55: ... the point of view of that charge, it’s inside the black hole, but from your point ...
 11:18: You interact with the local curvature of spacetime, which is produced by the past mass, which from your point of view is on the event horizon.
 12:00: ... seemingly different pictures all point to the same result  the black hole will eat you right up, and even as ...
 14:03: ... its false, overinflated informational volume." Agentdarkboote and Meisam pointed out an error  or at least, a missed ...
 14:41: Thanks for the details guys  we went deep on this one and may have missed a few points.
 16:25: ... speaking of the Milky WayAndromeda collision, Roli Rivelino points out that way back in our 3body problem video, they asked how we can ...


20220119: How To Build The Universe in a Computer
 01:57: At any point on the disk, a galvanic cell could determine in which direction the intensity of light was strongest.
 07:17: The force at each point can then be solved using Fourier transform methods, which can be very fast.


20220112: How To Simulate The Universe With DFT
 03:17: Let’s say we have a fairly crude grid of 10 data points in 1D.
 03:21: The 3D equivalent would need 10^3  1,000 data points.
 04:06: ... the one who pointed out that to describe the iron atom on a course grid, you’d need to store ...
 05:07: For every coordinate point for electron one, we need to consider separately every coordinate point for electron two.
 05:15: ... for a given pair of coordinate points for electrons one and two, we need to consider every possible point for ...
 06:37: ... we can throw away most of configuration space and consider just the few points in that space where the particles actually exist at a given point in ...
 18:51: ... want to avoid the Reapers then that might be doing just that. Defeshh points out that it’s scary to imagine an alien civilization that would need the ...
 20:07: ... Angelbar points out the other thing we might do with a matryoshka brain powered by a a ...


20211229: How to Find ALIEN Dyson Spheres
 04:10: Dyson’s original notion was simply to search for points of light with temperatures of a few hundred Kelvin, but emitting the power of an entire star.
 07:24: But from our great distance the light from the star and the sphere would be blended into a point.
 11:33: At this point, our surveys have found no evidence for starspanning megastructures.
 13:48: It would also point to a possible future for humanity  something we might want to do when we grow up.


20211220: What Happens If A Black Hole Hits Earth?
 09:03: ... seismic waves would reach all points on the Earth’s surface. Even at the lowest mass possible for a ...
 11:02: ... sending matter out in all directions. This makes a crater basin at the point of contact, and a gentle sloping ‘ejecta blanket’ around it. But when a ...
 12:01: ... by regular asteroid impacts, and a line of that fancy quartz should point from one crater to the other, though we’d need to actually go back to ...
 15:30: ... Dean made a point that I missed in that MOND episode. And that's that we’ve observed ...
 19:14: ... points out that any welldeveloped intuition for physics points to the ...


20211210: 2021 End of Year AMA!
 00:02: ... really a great one how is it that exchanging a particle between two points can cause those those points to come together surely the momentum ...


20211117: Are Black Holes Actually Fuzzballs?
 00:39: ... matter should contract to a single point of infinite density  the singularity  which is surrounded by a surface ...
 03:57: When we see an apparent paradox in physics, it’s really a clue pointing to a gap in our understanding.
 06:01: ... because instead of collapsing all of a black hole’s mass into a single point, it gets distributed around the ring structure of these ...
 12:04: One dimension means a line, so a 1D black hole is just a segment of a line with a point of infinite density on it.
 12:10: The event horizon is just the pair of equidistant points on the line inside of which escape is impossible.


20211110: What If Our Understanding of Gravity Is Wrong?
 05:38: ... need some type of physical dark matter in clusters is seen as a strong point against MOND in its first incarnation at ...
 05:56: For now Point 2.
 06:25: But let’s address point 3 anyway.
 12:54: At this point the two theories are in a bloody theoretical knife fight, where the knife is Occam’s razor.
 17:17: A few people pointed out an error  I said that the action reduces to an integral over proper time in general relativity.
 17:39: ... principle of stationary action  and the maximum is also a stationary point  of proper time and of the ...
 17:55: Many of you point out that you’re already adherents of the principle of least action.


20211102: Is ACTION The Most Fundamental Property in Physics?
 00:02: ... 40 AD, Heron of Alexandria noticed that when light moves between two points, out of all the possible paths between them, it follows the shortest one. ...
 04:29: ... be possible to figure out the path that any object will take between two points as long as you can find a way to determine which has the minimum action. ...
 09:24: ... is at a minimum or maximum. That should correspond only to the central points of those bands. However we see particles landing at every location in ...
 09:56: ... only where this quantum action varied slowly  near it’s stationary points, just like with classical ...
 11:38: ... that could lead to that destination line up. Away from those special points, very tiny changes in the path lead to rapid changes in the phase, ...
 11:59: ... Dirac started to guess, particles tend to end up near the stationary points of the quantum action. In the path integral, this happens for paths that ...
 13:46: ... guided by mysterious principles, not least of which is the Action  pointing the surest way to the fundamental nature of space ...
 17:15: This is all some pretty obtuse stuff, and some of you did better at explaining the point of constructor theory than I did, so let me just summarize.
 17:24: ... Andy points out that constructor theory seeks to narrow down the space of all ...
 18:34: ... are unaware, Isaac Newton was an avid alchemist. But I think there’s a point to be made ...


20211013: New Results in Quantum Tunneling vs. The Speed of Light
 05:56: It seems natural to define those times as whenever the center of the wavefunction passes the start and end points.
 06:24: You’ll get a shorter time than if you clicked for the same point at both tunnel ends.
 06:45: It’s hard to measure the travel time of a quantum train OR a quantum wavefunction because it’s hard to define the start and end points.
 07:28: ... instead ask the following: is it possible to send a message between two points that are separated by a barrier faster than you can transmit the same ...
 12:02: The point is that the theory and the experimental tools are now converging on a way to answer our questions once and for all.
 14:43: ... direction of the Higgs field becomes free to vary wildly and adjacent points in the field are less coupled to each ...
 14:53: Only when the field cools down to adjacent points become more tied to each other.


20211005: Why Magnetic Monopoles SHOULD Exist
 02:37: The divergence is just this mathy term for the amount that a field points inward toward a sink or outward toward a source.
 10:05: ... can have a little internal arrow that points in a particular direction  not pointing in physical space, but in the ...
 10:13: ... is the absolute length of that internal vector  not the direction it’s pointing. ...
 10:34: ... the direction of the Higgs field varies smoothly from one point to the next, it can still have these sorts of knots  places where the ...
 10:47: These are topological discontinuities  points that can’t be removed by a smooth defomation of space.
 15:04: 4fmagnet points out a potentially misleading point in that episdoe.
 15:39: ... points out that we don’t need to keep talking about spin as this ...


20210921: How Electron Spin Makes Matter Possible
 01:13: ... more sensible case of a single 360 degrees rotation back to the starting point. Integerspin particles are bosons, and they are the force carrying ...
 03:46: ... untwist it without rotating either end of the belt. Watch. Now at this point I am letting go of the buckle  but the important thing is that the ...
 06:49: ... rotation puts a spinor perfectly out of phase compared to its starting point. So a 360 rotation introduces a negative sign to the spinor ...


20210915: Neutron Stars: The Most Extreme Objects in the Universe
 07:06: ... relying on our theoretical calculations here  we’re beyond the point where we can duplicate these energies and these ...
 13:06: ... from a binary partner star. Its mass is growing and at some point soon it’ll form an inescapable event horizon and we’ll ...


20210907: First Detection of Light from Behind a Black Hole
 02:48: ... basically you watch the quasar, which is just a faint point of light on the sky, and stretch it into an even fainter flickering ...
 11:54: ... it when we can map the space around black holes by watching flickering points in the sky, and in that flickering reconstruct how light reverberates ...
 13:05: ... when they come out of warp, which could potentially be seen if they were pointed at ...


20210818: How Vacuum Decay Would Destroy The Universe
 01:31: ... an analogy. Think of all space as being sort of springy at every point. As a simplistic example, imagine a rubber ring at ...
 02:18: ... more energy to get further away from the minimum  the equilibrium point, just like it takes more energy if you want to deform the rubber ...
 06:08: ... universe filled with the Higgs field in a false vacuum. At a single point in space, a quantum tunneling event drops the field ...


20210810: How to Communicate Across the Quantum Multiverse
 02:22: OK, cute analogy, but perhaps pointless because we don’t even know if Many Worlds is right.
 02:29: ... Interpretation, which says that the wavefunction collapses at the point of measurement, leaving only one reality; or de BroglieBohm pilot wave ...
 04:30: ... because that can produce an oscillation, and in which adjacent points pull on each other, cause that can cause the oscillation to ...
 05:21: ... back to equilibrium is just proportional to the displacement at each point. That’s the case for the most idealized oscillation  the simple harmonic ...
 06:09: ... in the physical world the superposition principle only holds to a point. Real pond surfaces or air density fields don’t behave like simple ...
 09:57: ... device and then you measure the direction of the spin. It has to be pointing either to the north or south poles  we’ll call them up or down. In the ...
 17:12: ... but instead by murmurs of “huh, that’s weird”. Vingador das Estrelas pointed out that the more common version is “The most exciting phrase to hear in ...


20210803: How An Extreme New Star Could Change All Cosmology
 00:00: ... by murmurs of “huh, that’s weird”. Well, we’ve just observed a faint point of light on the sky whose weirdness could change the way we think about ...
 00:21: ... in the way that we thought all white dwarfs formed. This one peculiar point of faint light may change our understanding of not just white dwarfs, ...
 02:51: ... so the mystery deepens. At this point, astronomers decided that the object was weird enough to bring some ...
 03:58: ... that even our highestresolution telescope cameras see them as single points of light. But astronomers have a clever trick. If you know how much ...
 06:51: ... are driven down to fill all of the lowest energy states. At that point it can’t collapse any further because there’s nowhere for the electrons ...


20210721: How Magnetism Shapes The Universe
 03:09: Speaking of compasses  a minute ago we were standing at the north pole with a compass needle pointing straight up.
 07:35: If the electric and magnetic fields of a collection of photons all tend to point in the same direction, we say the light is linearly polarized.
 14:46: Seems a fair point.
 16:46: A related point is regarding probability.
 16:49: ... and Master Piece point out that if many worlds gives one world per option, then what does that ...
 17:03: This is a really good point. and one we’ll explore in that halfpromised episode I just mentioned.
 18:20: ... Barefoot also point out that this divide isn’t needed for quantum mechanics to work  its ...
 18:33: And anyway, as many of you pointed out  we don’t really need wavefunction damping if we have the time variance authority pruning worlds for us.


20210713: Where Are The Worlds In Many Worlds?
 02:13: You can calculate the overlapping pattern at any point in time by calculating the motion of all ripples separately and then adding them together.
 02:43: The superposition principle only applies up to a point.
 03:06: The main point is that this holds approximately for familiar waves, up to some amplitude.
 04:23: ... is chosen from a vast array of possibilities, a sprinkling of the high points of the cosmic ...
 05:59: The wavefunction of the electron joins the wavefunction of the detector screen at all points, rippling onwards.
 06:54: The Copenhagen interpretation says that at some point in this process, most of the wavefunction vanishes.
 07:57: ... troughs could still line up in a systematic way to produce high and low points in the wavefunction  meaningful blips in the probability ...
 08:40: At this point we may say that the “worlds have split” because there may be no way bring them back into coherence.


20210707: Electrons DO NOT Spin
 03:48: ... need to be spinning faster than the speed of light. This was first pointed out by the Austrian physicist Wolfgang Pauli. He showed that, if ...
 05:37: ... that depends on the direction that these little magnetic moments are pointing relative to that field. Those that are perfectly aligned with the field ...
 06:10: ... might expect a blur of points where the silver atoms hit the detector screen  some deflected up ...
 08:50: ... objects, a rotation of 360 degrees gets it back to its starting point. That’s also true of vectors  which are just arrows pointing in some ...
 09:30: ... rotate the cube by 360 degrees, the cube itself is back to the starting point, but the ribbons have a twist compared to how they started. ...
 09:59: ... think of electrons as being connected to all other points in the universe by invisible strands. One rotation causes a twist, two ...
 11:44: ... spinor aka the electron, imply that even if the electron is point like, it's angular momentum can arise from an extended though ...
 16:27: ... Hansen makes the same point, asking if the conditions of the Big Bang meant everything started ...


20210623: How Quantum Entanglement Creates Entropy
 06:56: ... heads AND tails until you look at the result, at which point it becomes either heads or ...
 12:35: ... that are preserved through this diffusion of entanglement pointer states in the language of quantum darwinism. Over time, ...
 13:09: ... as an extra trick, it also defines the arrow of time which itself points in the direction of increasing entropy and multiplying ...
 16:39: ... of you replied with good answers  Daemonxblaze points out that quantum teleportation, aka quantum ...
 17:55: ... momentum of the photon used to measure that position. F points out that surely we should have some idea how that momentum transfer ...
 18:41: ... John points out that the Kessler syndrome is like zombies  ...


20210616: Can Space Be Infinitely Divided?
 05:08: ... point I want to focus on today is that through the uncertainty principle ...
 07:10: ... increases. You’re still winning the uncertainty game  up to a point. When the wavelength of the photon reaches exactly ...
 08:37: ... is about equal to the entire massenergy of the electron. At that point, you can’t say there’s just one electron. The uncertainty in the ...


20210609: Are We Running Out of Space Above Earth?
 02:41: This sort of collision cascade is known as the Kessler Syndrome, after Donald Kessler who pointed out the danger in 1978.
 11:12: Presumably, at some point, some of them without the same care that SpaceX claims to be taking.


20210525: What If (Tiny) Black Holes Are Everywhere?
 04:49: At that point you need a proper theory of quantum gravity to describe the process.
 05:59: And at some point, there may be no allowed transitions that can take away the last of the black hole’s mass.
 06:20: In other words, when you get to the point where a single photon would take away the rest of the black hole’s mass.
 14:38: Well, not officially LIGO, but LIGO scientist Maggie Tse reached out to us to point out an error.
 15:08: ... the Uncertainty Principle”, but you rightly  if pedantically  pointed out that it should have been bending or correctly using the uncertainty ...


20210519: Breaking The Heisenberg Uncertainty Principle
 00:07: And in some cases succeeding, by squeezing the Heisenberg uncertainty principle to its breaking point.


20210511: How To Know If It's Aliens
 06:27: ... a relevant quote from Sherlock Holmes on this point. "When you have eliminated the impossible, whatever remains, however ...
 17:14: ... Chaps correctly points out that there are scientists who have pushed the black hole dark matter ...


20210421: The NEW Warp Drive Possibilities
 07:55: Bobrick and Martire also point out that there’s still no way to accelerate a warp bubble across the light speed limit.
 08:28: ... pointed out by Fransisco Lobo and Matt Visser, if sublightspeed or subluminal ...


20210413: What If Dark Matter Is Just Black Holes?
 01:25: ... fact that we know black holes are actually real seems like a significant point in their favor as an explanation for dark matter  it’s more than we can ...
 07:40: At this point, gravitational lensing becomes the goto method for dark matter hunters.


20210407: Why the Muon g2 Results Are So Exciting!
 00:13: Then that little glitch maybe pointing the way to layers of physics deeper than we've yet imagined.
 10:29: That was a three point something sigma detection.


20210323: Zeno's Paradox & The Quantum Zeno Effect
 04:41: ... observation resets the trajectory to the start, at which point the wavefunction has to start evolving from scratch  but you keep ...
 08:27: But I want to highlight one particular point.
 13:40: ... Bryant offers some excellent clarification, pointing out that that the CMB number isn't actually a "measurement" of the ...
 16:13: But the point is that scientists do celebrate and embrace wrongness for the way it helps point us towards increasing knowledge.
 16:20: And it's really worth pointing out that this stuff is aspirational  the tendency to requestion everything is hard baked into the scientific process.


20210316: The NEW Crisis in Cosmology
 10:40: ... lens, resulting in multiple images of the quasar from our point of view. Quasars are violent beasts  the maelstrom ...
 16:28: ... Kerruish and clearnightsky saw the Feynman connection also  pointing out the Huygen's principle feels like Feynman's path ...


20210309: How Does Gravity Affect Light?
 05:36: But for that to be the case, light must travel a curved path from the point of view of the accelerating frame.
 06:47: But light is frozen in time from its point of view.
 07:40: The idea is that any wave can be described as an infinite number of pointlike oscillations, each of which produces new waves.
 07:58: At any point in time, the expanding ripple can be thought of as an infinite number of sources of new circular ripples, or wavelets.
 11:52: So I guess the question I’d be asking at this point is why did Einstein’s calculation even work.


20210224: Does Time Cause Gravity?
 05:44: The 4velocity of a massive object is pointed almost entirely in the time direction.
 07:05: Like  what about a particle with no size  supposedly pointlike particles like electrons, quarks, etc.


20210217: Gravitational Wave Background Discovered?
 00:00: ... what is known as a quadrupole wave if the wave passes through a ring of points those points would move in and out like this okay so imagine these ...


20210210: How Does Gravity Warp the Flow of Time?
 07:42: ... of what is “simultaneous” to current moment flips at the turnaround point, so that she misses a bunch of the ticks of her brothers ...


20210126: Is Dark Matter Made of Particles?
 09:26: ... expected for a certain type of dark matter  which some would say is a point in favor of ...
 14:52: The shockwave hits the base of the ladder at the same position in the barn from either the ladder or the barn’s point of view.
 14:59: ... Suku points out that the difference between the traveling and stayathome twin is ...


20210119: Can We Break the Universe?
 00:53: But the point of this episode is to go much further  we’re going to try to break the universe by pushing these paradoxes beyond the limit.
 01:09: ... the clocks on the spaceship will appear to tick more slowly from the point of view of a stationary observer back on the ...
 02:41: ... spaceship moving at near lightspeed, the universe could contract to the point that the spaceship wraps all the way around and its nose smashes into ...
 04:57: ... allow us to track the apparent passage of time back on Earth from the point of view of the ...
 05:28: In total, the traveler counts fewer Earth years because she misses some time in the middle corresponding to the turnaround point.
 05:36: Those years do happen back on earth, but they don’t correspond to any time point that happens to the astronaut.
 07:00: The traveling twin declares that multiple points in the stationary twin’s past and future are all happening in her present.
 08:52: At some point, the ladder appears to be inside the barn with both doors closed.
 08:57: Let’s switch to the point of view of someone moving with the ladder.
 10:35: At no point is it entirely inside the barn.
 10:44: OK  we’re finally at the point where we can answer the money question.
 11:18: So that’s also the line on which we lay down points along the length of our spaceship.
 11:26: And look  the spaceship DOES cross this point in space  our seam  and sort of exists there simultaneously.
 11:40: They exist at the same point in space at different points in time.
 13:38: So the answer I think is that we don't yet know  but it's important to point out that the system used in the experiment IS a genuine quantum system.
 14:01: But I take your point  can we really be sure that the same underlying complexity exists in real atoms?


20210112: What Happens During a Quantum Jump?
 08:30: ... has advanced to the point that we can not only see individual quantum jumps  we can monitor their ...
 11:50: ... considered by many to be a point of philosophical preference whether you roll dice with Bohr and ...


20201222: Navigating with Quantum Entanglement
 03:55: At any point on the surface of the earth, our geomagnetic field can be described with just a few properties.
 04:00: There’s their vertical orientation or “inclination”, so whether they’re parallel to the ground or point into the ground.
 04:12: This “declination” points towards the magnetic poles, which are offset from the true poles defined by Earth’s rotational axis.
 04:19: There’s also a directional arrow attached to the lines  as in one direction pointing “north” and the other “south”.
 06:35: ... the spins: the first is the socalled singlet state, where the spins are pointing in opposite directions  we'll call them up and ...
 15:29: Many of you pointed out how hard it is to wrap your heads around the sort of timescales we talked about in that episode.


20201215: The Supernova At The End of Time
 05:49: ... this degeneracy pressure could support a dead star up to a point  if that stellar remnant’s mass was too high then a new process would ...
 09:13: But assuming protons are stable, we’ll reach a point where the universe consists of only iron stars and radiation.
 14:17: The point here is that even the idea of "it has happened" is a relative concept  relative to the observer.


20201208: Why Do You Remember The Past But Not The Future?
 03:36: But the point remains  there is a record of the past in the object, and to some degree that past can be reconstructed.
 04:11: ... of this seems too mysterious, but let’s look at this from the point of view of the timeless laws of physics and see if we can identify where ...
 05:23: But the point still holds  internal information can be used to reconstruct the past, and that’s a type of memory.


20201118: The Arrow of Time and How to Reverse It
 05:10: ... see what happens in the following time steps.Even though the velocities pointed in random directions, the cluster will inevitably disperse. Entropy ...
 06:19: ... if you live on either side of the starting, lowentropy point, you perceive an asymmetry in time  particles expanding, entropy ...
 06:57: ... a minimum, and then will be seen to increase  now on both sides of the point in time of that ...
 11:16: ... dropped a lot of wisdom as always. I’m going to try to restate one point to see if I understood. Dr. Diagrams can correct me if I mess it up. So ...


20201111: Can Free Will be Saved in a Deterministic Universe?
 00:36: In it, the past and future have a sort of eternal timeless existence from the point of view of some godlike observer outside both space and time.


20201104: Electroweak Theory and the Origin of the Fundamental Forces
 05:18: ... because it should be possible to change it however you like at any point in space and still get the same physical ...
 06:05: ... said that at each point in space, the physics shouldn’t change when we shift both the real and ...
 09:35: Consider a magnetic material, made up of many little magnetic dipoles, like little bar magnets that can point in different directions.


20201027: How The Penrose Singularity Theorem Predicts The End of Space Time
 01:17: ... itself was doomed to fall inwards towards a central point. At that socalled singularity, the gravitational field becomes ...
 01:58: ... even whether such dense matter would really contract into a single point. It only showed that, once socontracted, the resulting black hole ...
 02:48: ... that normal, messy objects could never collapse into a perfect point. Surely any tiny deviation from spherical symmetry would ...
 05:55: ... has this property that null geodesics  and so any light  pointed outwards from the surface actually move downwards. Any closed surface ...
 06:38: ... the progression of space and time beyond one of these focal points. In other words, space and time end at the ...
 07:05: ... otherwise. Imagine a pair of light rays emerging from the same point and then focused back towards each other. Both are equally the ...
 08:11: ... north pole you’re no longer on the shortest path to any new point that you reach, and at the same time you reached the ...
 08:49: ... a Schwarzschild black hole, time ceases at the pointlike central singularity, while in Kerr black holes space ends at the ...
 09:31: ... through our entire universe towards the Big Bang. Now at this point we’d known for 40 years that the universe is expanding, and ...
 10:36: ... Time itself could not be traced beyond this point  which suggested that time really started at the Big Bang. Hawking ...
 11:10: ... singularity theorems must be wrong  or at least point to wrongness. They give us the predictions of pure general ...
 13:38: ... some would argue that means many worlds. Michal Grno points out that we forgot to mention Carlo Rovelli's relational QM ...


20201020: Is The Future Predetermined By Quantum Mechanics?
 04:03: At which point, the wave function collapses into a defined state.
 12:39: Anonymous makes some important points, I'll summarize.
 14:03: And speaking of presentism, Carl Stanland raises a point that highlights another objection that I have to the concept.


20201013: Do the Past and Future Exist?
 02:08: Newton assumed that all particles, all observers, all points in space were ruled by a single, constantly ticking clock.
 07:07: From your point of view, you are motionless.
 10:10: After all, they could have travel to those points from our own past.
 10:54: ... of someone else on your slice of present could be literally any point in your ...
 13:36: ... Williams points out that any Venusian life that we find is very likely from Earth  ...
 13:44: And Afto Kinito points out that it could easily have happened in the other direction  Earth life being seeded by Venusian meteorites.
 14:22: ... my statement that it would be good news if the venus life was confirmed, pointing out that it would mean the great filter is in front of ...
 14:32: Just to explain this excellent point for those who don't remember every episode we ever did.


20201005: Venus May Have Life!
 05:24: Followup observations will confirm or refute this pretty quickly, but the detection is looking pretty solid at this point.
 10:27: ... where they act as nucleation centers for new droplets to form, at which point they become metabolically active ...
 10:53: An important point here is that Venus’s hellish conditions are relatively young only perhaps only around 700 million years old.
 11:29: The previous observations were relatively brief, but there’s now motivation to point our telescopes for much much longer at Venus.
 14:22: ... up, Mina86 pointed out that our use of mixing colors as an analogy for oneway functions in ...
 14:39: Our point was to illustrate oneway functions themselves, but the way we said it could have been interpreted as illustrating RSA.


20200928: Solving Quantum Cryptography
 05:16: For the full explanation, I’m going to point you to the episodes made by Infinite Series a while back.
 12:27: Suppose you have an enormous field dotted regularly with points.
 12:39: But here’s a question: What is the shortest vector, or distance from one point to another point?
 13:51: Mathematicians and cryptographers have decades of security to point to as proof of their encrypting and decrypting abilities.
 15:57: Many of you pointed out science fiction works that had similar critters.


20200921: Could Life Evolve Inside Stars?
 02:13: The transition between all points would be smooth, with the grain changing angle only slightly.
 10:03: ... of this paper are not pretending that any of this is likely  their point is more to show that other possible bases for life might exist, beyond ...
 13:26: So let’s identify those qualities that our beautycompass is pointing to.
 15:20: Shirsendu Chatterjee points out that it’s finally time to give the address to the time traveler’s party that we hosted a year ago.


20200908: The Truth About Beauty in Physics
 10:13: Just add an additional degree of freedom  actually a symmetry  at each point in space and electromagnetism appears, almost miraculously.
 12:54: But it also points us true, if we take care to apply scientific rigor in between leaps of intuition.
 13:02: ... judiciously, the intuition of beauty may ultimately point the way to the deepest truths, leading to the most beautifully ...
 15:40: The point is that there are some insanely rare interactions and extremely subtle deviations from the predictions of the standard model.


20200901: How Do We Know What Stars Are Made Of?
 09:50: By the way, the whole finding out what stars are made of thing wasn’t even the main point of Payne’s thesis.


20200824: Can Future Colliders Break the Standard Model?
 08:37: ... point of this upgrade isn’t primarily to access higher energies where new ...
 12:07: ... it helped compete against the Russians: He said, “Only from a longrange point of view, of a developing ...
 14:44: The key point is that space doesn’t have to flow directly towards the singularity.
 15:16: They start separate, and the event horizons move towards each other as they join, and at some point the event horizons touch and then merge.
 15:40: In principle there should be a point right at the center where there is no flow  if you were a pointlike particle you could just hang there.
 15:47: But everywhere else  including above and below that point the space is still flowing inwards.


20200817: How Stars Destroy Each Other
 01:17: At a critical point, that surface reached the temperature and pressure of a stellar core.
 01:39: There, the royal astronomers of King Sejong’s court in Korea recorded a new point of light in the constellation of Wei, in what we call Scorpius.
 02:28: ... days, if you point one of our newfangled giant telescopes at the same spot where the royal ...
 05:05: ... remnant core now contracts to the point that atomic nuclei are no longer distinct  instead they meld together, ...
 07:09: ... galaxy in gamma rays  the highest energy light there is  the brightest points you see are pulsars, and those gamma ray spots are pretty much always ...
 11:10: Why should the star have crushed down into a pointlike singularity at all?


20200810: Theory of Everything Controversies: Livestream
 00:00: ... accessible space for those testable predictions and we're at the point where we are uh exploring the untestable i think we should be bolder ...


20200728: What is a Theory of Everything: Livestream
 00:00: ... and the inner workings of the universe and be a really good starting point perhaps to kick off many more great discussions uh this year in the ...


20200720: The Boundary Between Black Holes & Neutron Stars
 12:34: ... horizon by throwoing more and more electric charge into it  Ultimantis points out that it would be increasingly difficult to do so as the black hole ...
 13:23: From your point of view  no, not really.


20200708: Does Antimatter Explain Why There's Something Rather Than Nothing?
 07:21: ... ways to see if it deviates from regular hydrogen  deviations that could point to the violation of CPT symmetry. ALPHA uses CERN’s proton synchrotron ...


20200630: Dissolving an Event Horizon
 02:57: Inside, we found that the rapid rotation has spun the pointlike singularity into a ring of infinite density.
 04:10: ... presence of electric charge at the central singularity  which pointlike in this case  results in a negative pressure that again resists the ...
 04:33: And just as with the rotating black hole, at some point the inner and outer horizons become one and vanish and you’re left with a naked singularity.
 04:43: ... the tipping point  when the inner and outer horizons are right next to each other  you ...
 13:11: ... the space between atoms in one aeon would be infinite from the point of view of observers from the previous ...
 13:59: A pointlike particle has size zero  that’s zero volume, zero radius.


20200622: Building Black Holes in a Lab
 03:05: ... and you have a black hole. The surface around the central, massive point where the waterfall of space equals the speed of light is our event ...
 04:55: At some point the flow is faster than the waves  and that’s your analog event horizon.
 11:04: ... of quantum gravity. Proponents of this line of thought have triumphantly pointed to experimental observations of analog Hawking radiation—in laser ...


20200615: What Happens After the Universe Ends?
 03:33: And there’s the key point: light does not experience the flow of time.
 05:12: They show how time will tick for any constantvelocity observer passing through this point.
 05:23: ... direct path between them  a path of constant velocity that reaches that point in space at the right instant in ...
 10:12: Similarly, the infinitesimal or “zerosized” point of the Big Bang can be rescaled into a finite space.
 15:47: I had pointed out that alien viruses would need to be DNAbased in order to infect DNAbased life.
 15:54: ... points out that the DNA of all life that evolved on earth uses the same code ...


20200608: Can Viruses Travel Between Planets?
 06:39: OK, all this talk of viruses hitching rides into space brings us to our last, and most scifihorrormovie relevant point.
 10:31: Beyond a certain point, a damaged genome renders a virus nonfunctional and can’t be reconstructed.


20200527: Does Gravity Require Extra Dimensions?
 01:42: And deviations from Newton’s description may point the way to an understanding deeper than Einstein’s.
 02:03: If we have a massive object, we can depict the gravitational force (field) from this object as little arrows pointing towards the object.
 05:57: ... there are 6 additional spatial dimensions, coiledup tight at every point in the extended 3D ...


20200518: Mapping the Multiverse
 04:54: The singular, central point has been spun out into a ring of infinite density.
 06:13: Same with the interior of a Schwarzschild black hole  every ball, every geodesic reaches the same point and, very importantly, ends there.
 08:54: At this point we can follow an outgoing geodesic across the inner horizon.
 14:55: ... personally think it will be  whatever points beyond the current mess may need to be revolutionary and come from an ...
 16:07: ... was the following: As you rewind the universe towards zero age, distant points in space end up closer and closer  and there is no point that is so ...
 16:27: So in an infinite universe, every definable galaxy or definable location ends up right here on top of us at some point in the rewind.


20200511: How Luminiferous Aether Led to Relativity
 05:08: ... between a pair of slits, like water waves do. These bright bands are points on the screen where the waveforms of light emerging from the two slits ...
 10:02: ... reflect this. That is the MichelsonMorley experiment. For extra genius points, they floated the whole setup in a tub of frictionless mercury so it ...
 14:42: ... even though ALL of the galaxies we can see were compacted into a tiny point. There were just infinitely many of those tiny ...
 15:13: ... what happened before 10^43 seconds  the socalled Planck time. At that point inflation seems to give our best picture, and I'm going to have to ...
 15:32: ... Steve asks what was the diameter of the universe at the most distant point represented by the cosmic microwave background ...
 16:48: ... of you pointed out how awesome a name Vesto Slipher is. Yes, Frank Henchy, he does ...


20200504: How We Know The Universe is Ancient
 16:49: ... Travel? I'd settle for a leisurely trip to the grocery store at this point of the ...


20200428: Space Time Livestream: Ask Matt Anything
 00:00: ... exciting so welcome normally I would offer you a drink but there's one point four thousand of you and we don't have that technology yet so fetch ...


20200422: Will Wormholes Allow Fast Interstellar Travel?
 05:17: ... at impossible speeds? Then you could potentially reach this strange point  the nexus between the white and black ...
 16:15: ... in my apartment I'm not floating off in space somewhere. But morpheox points out that I really am. We all ...


20200414: Was the Milky Way a Quasar?
 11:41: ... thousand times lower than that required for the Fermi Bubbles, evidence points to similar explanations in both cases — some combination of accretion ...
 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.


20200407: How We Know The Earth Is Ancient
 01:48: ... also a weirdly precise number. Both Ussher and Buffon are docked half a point for excessive significant figures. Buffon’s premise was clever, if ...


20200331: What’s On The Other Side Of A Black Hole?
 00:00: ... maps are useless inside black holes. At the event horizon  the ultimate point of no return as you approach a black hole  time and space themselves ...
 00:37: ... surface of the Earth in lines of longitude and latitude so that every point on the planet can be clearly defined with two numbers. Everywhere but at ...
 01:53: ... That’s because at the event horizon, time appears to freeze from the point of view of a distant observer. And the Schwarzschild metric is defined ...
 05:00: ... light rays going in the other direction? These don’t have a sensible point of ...
 14:15: ... points out that the way quantum states become increasingly entangled with their ...
 14:41: Yuval Nehemia points out that Wojciech Zurek looks like the physicist version of Bob Ross.


20200324: How Black Holes Spin Space Time
 09:17: ... the object is split into two pieces at exactly the right point, one half will go plummeting through the event horizon while the other is ...


20200316: How Do Quantum States Manifest In The Classical World?
 02:56: ... have a property called quantum spin. That spin has an axis that points in some direction, analogous to the axis of a rotating ball. To measure ...
 03:12: ... vertically and you might see that the spin axis is pointing up or down, measure horizontally and it’ll be pointing left or right. ...
 09:56: ... be aware of a measurement we look at a macroscopic indicator  say, the pointer on a dial of our ...
 10:14: ... a chain of quantum systems between that original atom and the pointer. Information spreads along this chain as these systems become entangled ...
 11:30: ... we call these pointer states. Pointer states are robustly copied and spread until the states ...
 11:48: ... what determines whether a quantum state can be a pointer state? Well to some extent the way you set up the experiment  whether ...
 12:33: ... any of this explain Schrodinger’s Cat? Well an important example of a pointer state is the position of a particle. Most quantum interactions depend ...
 13:22: ... superpositions are not. It still doesn't tell us why we observe one pointer state over another unless of course there are multiple of these ...
 13:47: ... At least according to the framework of decoherence and these propagating pointer states. The observable qualities of reality  object positions, feline ...


20200303: Does Quantum Immortality Save Schrödinger's Cat?
 04:33: ... the point is they can’t repeat the experiment  at least according the the ...
 06:43: Max Tegmark makes a good point regarding quantum immortality  which is that death is an incremental process, not a single quantum event.
 07:51: ... of the human race, which means we should find ourselves at a typical point the span of humanity’s ...
 09:54: ... pointed out that probably the global population will level off at 10 billion or ...
 12:03: ... Goswami points out that the different matter configurations between experimental ...


20200224: How Decoherence Splits The Quantum Multiverse
 06:33: That’s the case for two separate paths that reach the same point on the screen in the double slit experiment.
 06:59: Let’s also think about two paths that reach different points on the screen.
 07:30: ... of states  it passed through both slits AND it reaches both points on the screen  as long the wavefunctions defining those outcomes remain ...
 07:41: Now we’re going to talk about decoherence  the point where we lose our ability to distinguish the multiple histories.
 09:29: And we will come back to that point.
 12:10: At this point, as far as you’re concerned, the wavefunction has collapsed  decoherence has occurred.


20200218: Does Consciousness Influence Quantum Mechanics?
 02:58: That probability wave defines the location of the electron at any point IF you try to measure it.
 13:51: Some of those questions were answered, but I thought I'd add a few points here.


20200211: Are Axions Dark Matter?
 12:47: ... Ocelot pointed out a Medium article by Ethan Seigel that claimed that even if inflation ...
 14:39: ... also points out that eternal inflation must have had a beginning, so it hasn't yet ...


20200203: Are there Infinite Versions of You?
 03:19: ... etc of all particles  perfectly determines the future history of any point with that ...
 03:33: That is, until the disrupting influence of external regions has time to reach that point.
 05:32: But if there are finite starting points then at least SOME of those starting configurations have to be repeated infinite times.
 06:53: We can’t tune the starting conditions to an infinite degree and still get different results  and that’s the key point.
 12:29: Ilavenya rightly points out that no nice analytical solutions to the 3body problem exist in general relativity  Einstein's modern theory of gravity.
 13:31: So to remind you  Euler and Lagrange came up with a set of 3body configurations that are now known as the Lagrange points.
 14:14: These would no longer be called "Lagrange points", but they are true stable or metastable 3body orbits.


20200127: Hacking the Nature of Reality
 01:30: ... that matters are the observables  the measurable start and end points of an ...
 06:19: But at the time, prior to the discovery of quarks, no pointlike, elementary nuclear particles were known.
 09:11: ... bootstraps”  the idea of raising yourself up without concrete starting point to push off ...
 14:13: Persona non grata asks whether migration traps are like Lagrange points.
 14:17: Not really  in fact we covered Lagrange points last week.


20200120: Solving the Three Body Problem
 06:43: ... the Earth’s orbit around the Sun. We now call these the Lagrange points, and they’re useful places to park our ...


20200113: How To Capture Black Holes
 12:49: ... couple of you point out that the idea of black holes birthing universes still doesn't ...


20191217: Do Black Holes Create New Universes?
 05:06: The point is to instead ask: what if it’s true?
 14:40: ... point it totally valid  in fact a cromagnon should reach the same conclusion ...
 15:20: ... point is if any given individual assumes that we're randomly sample from all ...
 17:20: The point is that you need to take into account prior knowledge when you're defining your reference class.


20191209: The Doomsday Argument
 15:16: One commenter, O.N., pointed out that an infinite universe is technically possible within a bubble that otherwise looks finite from the outside.
 15:37: ... Spring points out that there are flat geometries that are not infinite, but rather ...
 16:21: ... excellent Forbes article on this closed universe paper emphasized a point that we mentioned only in passing that is worth repeating: that is that ...


20191202: Is The Universe Finite?
 01:38: ... from previous satellites, and the initial analysis from the Planck map, pointed to a universe that is infinitely large and geometrically flat, and is ...
 04:34: Like I said, previous studies were pointing to a flat universe.
 07:25: They found the range of models that fit the shape of the power spectrum, and for the most part those pointed to positive curvature.
 10:34: That would be surprising because most data points to a flat universe.
 15:04: ... besides being a witty quip, this gets to an important point: anthropic seletion only demands that our universe be able to produce ...
 15:29: Regis Bodnar has a great point: while it may be technically possible to observe a typical universe, it's perhaps impossible to define one.


20191118: Can You Observe a Typical Universe?
 15:26: ... few of you also pointed out that I missed one possibility  perhaps the dials defining the ...
 15:44: ... right  that's possible  but the point is that UNLESS that principle is somehow connected to the universe's ...
 16:26: ... makes a great point: surely if this were the Goldilocks universe there would be life on ...
 17:09: Keith Strang correctly points out that we also have to talk about fine tuning of parameters to get a multiverse in the first place.


20191111: Does Life Need a Multiverse to Exist?
 12:51: Well this is a highly controversial point, but despite popular opinion it’s not untestable.
 13:28: ... Juice points out that the formation of the moon due to a giant impact would also have ...
 14:48: This is a valuable point to bring up, and several eminent scientists feel the same.
 15:34: ... 213 points out that endosymbiosis  the process by which we think mitochondria got ...
 15:51: ... a very nice point, Roman, although this particular point was only intended as an example of ...
 16:03: ... also worth pointing out that this particular evolutionary event, the first evolution of the ...


20191104: Why We Might Be Alone in the Universe
 04:53: ... billions of potential starting points for life in the Milky Way alone, even if we restrict ourselves to boring ...


20191021: Is Time Travel Impossible?
 01:56: So if you could travel faster than light you could navigate a path to a point in spacetime before you departed.
 03:46: ... it can be stretched in such a way as to create a tunnel between two points – and one whose internal distances could be very short, even if the ...
 04:00: This has the obvious benefit of allowing you to teleport between distant points in space, but also between distant points in time.
 07:40: A spaceship traveling along one of these curves could return to a point in its own past.
 08:59: ... hole, which is probably the only thing you really want to do at that point. ...
 09:53: But there are no true paradoxes – only seeming paradoxes that point to a gap in our understanding.


20191015: Loop Quantum Gravity Explained
 07:33: Connections are mathematical functions that tell you how something, like a vector, changes as it moves between two points in a space.
 09:22: They evaluated these connections over closed loops – so each point connected back to itself.
 15:22: Still, we'll probably see a lensed gravitational wave at some point.


20191007: Black Hole Harmonics
 05:37: They looked for overtones in the ringdown from right at the point of black hole merger.
 06:34: ... was nicely simulated by spherical harmonic oscillations right from the point of merger, so it was not the chaotic mess previously ...


20190930: How Many Universes Are There?
 03:13: That means the number of bubbles forming at each point in time should be proportional to the volume of the inflating universe at that time.
 12:42: And it might be very high – especially if the inflaton field is highly correlated from one point to the next, as in slowroll inflation.


20190923: Is Pluto a Planet?
 13:33: Maybe at some point in the future, as we learn more about how different worlds form, astronomers will change the definition of planet again.
 15:06: It'll be discovered in the late 2050s, at which point it won't be considered remarkable in any way.
 15:44: That's a fair point.
 17:18: Speaking of roofs, a few of you point out that the best Martian option may be underground cities.


20190916: Could We Terraform Mars?
 12:48: The good news is that those comets brought with them a LOT of water, so we have deep global oceans at this point.
 16:31: This is the simplest type of quantum field, consisting of only a single scalar value at all points in space.
 18:06: ... points out that while Venus lacks an Earthtype intrinsic magnetic field, the ...
 18:16: That's a nice point, EarthKnight.


20190826: How To Become an Astrophysicist + Challenge Question!
 03:35: ... professorship at the City University of New York And that was the first point in my entire career where I thought I might be able to stick with this ...
 07:11: ... just to improve your chance of getting into a ph.d program at Any point keep your mind open about other career ...


20190819: What Happened Before the Big Bang?
 00:35: The universe almost certainly did not explode from a singular point.
 08:06: ... would lead to slight differences in when the inflation ends from one point to the next But quantum fluctuations come in all sizes and a rare strong ...


20190812: Exploring Arecibo in VR 180
 01:02: ... this size So Arecibo relies on some incredible ingenuity to allow it to point at different locations on the sky most telescopes radio or optical use ...


20190806: What Caused the Big Bang?
 04:13: ... make sense presumably the universe also needed to stop inflating at some point giving way to the regular Hubble expansion that we see ...
 05:02: Now, a field is just some property that takes on a numerical value at every point in space.
 09:04: Inflation would stop at that point.
 09:07: ... of space adjacent to that point would also be dragged out of the local minimum towards the true vacuum ...
 09:35: And just like a growing ice crystal, this effect will propagate outwards from the starting point, which we call a nucleation point, by analogy.
 10:14: ... like the entire floor of the field is shifted down at every point in space; what was once pure inflaton field is converted to a stack of ...
 10:59: ... this point, the universe should evolve as the rest of the Big Bang story predicts: ...


20190718: Did Time Start at the Big Bang?
 00:25: ... and energy should once have been compacted into an infinitesimally small point  a singularity. It's often said that the universe started with this ...
 01:56: ... What does it really mean for all of space to be compacted into a single point? ...
 03:27: ... in terms of the scale factor That's the distance between any two points in space at some moment in time Relative to their distance at some other ...
 04:32: Do that enough times and any two points, no matter how far apart they were, will end up as close together as you'd like.
 04:38: ... this way doesn't leave us with a singularity The singularity is when all points are not just next to each other but literally in the same spot at which ...
 05:15: ... the infinite universe becomes infinitesimal all points become the same point and threedimensional space becomes zero ...
 06:02: ... are the grids we use to map spacetime Remember that in our rewind all points in the universe get arbitrarily close together before merging at T ...
 07:22: ... with them Or they start depending on how you want to think about it The point is that in the pure Einsteinian picture There is no before the Big Bang ...
 08:04: from the pure Einsteinian point of view It's meaningless to ask what happened before the Big Bang or after reaching the black hole Center?
 08:52: ... believe its prediction that all space was compacted into a single point and that this is where Time started. Ok. So what are the ...


20190715: The Quantum Internet
 04:40: ... that as soon as you try to read a qubit, which you have to do at some point to make the copy, you disturb the state in such a way that you will ...
 07:18: ... this point the original quantum state of photon C, which contains the message, has ...
 12:04: ... points out that proliferation is an especially lower risk from thorium reactors ...
 12:29: This is a good point, it's not quite foolproof because the decay products leading to protactinium can potentially be separated and removed.
 13:53: Yeah, I breezed over that point.
 14:45: KowashiHitori points out that Wind and solar won't build battlemechs... just saying.
 14:52: Now, this is a very important point.


20190701: Thorium and the Future of Nuclear Energy
 16:59: ... galaxies for example Seyfert galaxies and they can have their Jets pointing in any direction at right angles to the disk or even straight into the ...


20190617: How Black Holes Kill Galaxies
 13:10: Now, this is a cool point.


20190606: The Alchemy of Neutron Star Collisions
 12:15: ... much scientists can find out with so little in this case from a single point of light that is that distant quasar."  Jan Pieter Cornet asks ...


20190516: The Cosmic Dark Ages
 10:10: ... once hardultraviolet, but now infrared. Everything to the left of this point was once even more energetic UV, but now it’s gone – it was redshifted ...
 13:43: ... and several others also point out that internet security isn't doomed in the wake of quantum computers ...
 14:38: ... relays are weak points, especially if the states revert to classical information while being ...
 14:48: ... that a real quantum internet is a long way off. That said, the entire point of talking about quantum cryptography was as a way to describe some of ...


20190509: Why Quantum Computing Requires Quantum Cryptography
 16:39: At what point do we just give up trying to disprove the old man and just settle for the fact that it's probably all right?


20190501: The Real Science of the EHT Black Hole
 01:53: We can think of light from a very distant point as coming in a series or plane waves.
 02:08: And that phase difference itself is different for light coming from different points on the sky.
 02:13: ... difference precisely, we can measure the angular separation between two points to a precision far better than any single ...
 02:27: It resolves between two points on the sky if the separation between those points results in a relative phase shift of around one wavecycle.
 02:36: ... to reach the second telescope should be different for the two different points on the sky, and that difference should be of order one wavelength for ...
 02:51: ... means that an interferometer can resolve points separated by an angle that is the same as the ratio between the observed ...
 05:58: The event horizon itself is the point where even outwardpointing light can’t escape the black hole.


20190424: No Dark Matter = Proof of Dark Matter?
 00:03: ... we covered recently but no consistent theory has appeared a few points have come out in favor of the dark matter as mater hypothesis versus the ...


20190410: The Holographic Universe Explained
 03:03: ... the point of view of outside observers, its contents is smeared into 2D on the ...
 06:11: ... example, you can change the scale at every point on the grid separately and not change the internal angles or the shapes ...
 06:36: This adds a degree of freedom everywhere – like a new infinite number line at each of the 2D grid points.
 09:57: These are like multidimensional strings that can serve as start and end points for strings, but also as spaces embedded within higherdimensions.


20190403: The Edge of an Infinite Universe
 01:02: ... a little picket fence around our little patch – meaningless from the point of view of the plain, but it makes our patch feel more homey and us less ...
 07:05: ... matter must originate at this point representing all of space in the infinite past, and must also converge ...
 08:15: ... connected a quantum field between two points at infinite distance – past and future  where he could define the state ...
 08:26: Then he placed a black hole in between these points and calculated how it perturbed the balance of a quantum field traced between them.
 10:37: Any two paths that are parallel at one point will diverge from each other in either direction.
 13:45: Every point on the flat surface maps to a set of paths through the hyperbolic interior – remember those circle arcs?
 17:16: Swole Kot asks if the last months in the big rip scenario would be a painful and horrible experience for any sentient life still around at that point.


20190328: Could the Universe End by Tearing Apart Every Atom?
 06:20: ... and with no gravitational bodies left to resist the expansion, all points in space will eventually be racing apart from each other faster than the ...
 09:38: In fact, at this point the cosmic event horizon is still about 200 million light years away.


20190320: Is Dark Energy Getting Stronger?
 09:07: That sounds like an obscure point, but this is going to give us our standard candle.
 11:02: The red points are consistently below the dashed line for large distances and redshifts.
 12:27: This scenario is known as the Big Rip, and we will probably do a whole episode on it at some point.


20190313: Will You Travel to Space?
 04:47: And that means we can we hope we can generate funds where we can then start thinking about pointtopoint travel at great speeds.
 04:57: ... overriding all of this, both space and pointtopoint travel and satellites in space, is a desire to bring the environmental ...
 08:09: ... for suborbital travel. And this is what Richard means when he says pointtopoint travel. These spacekissing trajectories could one day allow us to ...
 13:27: ... points out that atoms are perpetual motion machines, and there are hydrogen ...


20190306: The Impossibility of Perpetual Motion Machines
 08:48: ... entire playlist on the quantum vacuum for the physics, but the important point is that any energy of the vacuum is exactly the same ...
 15:22: Julio Toboso García points out that the method used to model the CMB fluctuations  multipole expansion  sounds a like Fourier Analysis.


20190220: Secrets of the Cosmic Microwave Background
 14:23: ... Let's see what you guys had to say flux_capacitor and Marcus Kunrath point out that the baryonacoustic oscillations should have produced bubbles, ...


20190207: Sound Waves from the Beginning of Time
 11:47: ... were when they formed, and we can see how big they are at different points in the modern universe from our redshift ...
 13:26: ... into a big crunch due to everything quantum tunneling towards a single point? ...


20190124: The Crisis in Cosmology
 14:01: Andrew Paulfreyman points out that...
 16:05: The point is that you can't tell which of the two you're in.


20190116: Our Antimatter, Mirrored, TimeReversed Universe
 03:02: ... have negatively charged nuclei which means their nuclear magnetic fields point in the opposite direction to regular matter relative to their angular ...
 10:54: ... and spin. Essentially you're taking all particles in the universe and pointing them back in the direction they came from. If the T in CPT is conserved ...
 13:52: ... last week's comments next time  in fact, I really want to address a few points made by FieldStrength on the PBS Space Time subreddit: they covered all ...
 16:06: ... other point is that the large undefined parameter space of string theory  the so ...
 16:49: ... point being that while not wrong there's not yet a way to properly test his ...


20190109: Are Dark Matter And Dark Energy The Same?
 02:38: That’s a supersubtle point that took us like 5 episodes to explain.
 10:48: ... and this sinusoidal expansion, any slowdown happens near the turnaround point presumably tens of billions of years in the ...


20181220: Why String Theory is Wrong
 00:41: ... very first gauge symmetry  Weyl invariance Einstein pointed out that the proposal led to some absurd results, and so the idea went ...
 03:58: At every point in space, there's another direction to move: up, down, left, right, forward, back, and around.
 15:37: ... our own you had your own Reflections on the subject. socks with sandals points out that parity inversion isn't the only thing reflected in a true ...


20181212: Quantum Physics in a Mirror Universe
 00:02: ... you reflect the universe obviously it is difference or position vectors point in the opposite direction same with the velocity / momentum through our ...


20181206: Did Life on Earth Come from Space?
 00:37: ... field a chunk of impact debris has to be kicked to a minimum of eleven point two kilometers per second that's the escape velocity at Earth's surface ...


20181121: 'Oumuamua Is Not Aliens
 13:57: Thanks to Gustavo Valdiviesso for pointing this out.


20181114: Supersymmetric Particle Found?
 08:43: ... Derek Fox, Steinn Sigurdsson, and team point out that there's a version of supersymmetry that predicts exactly the ...
 16:06: And to end on a funny, Dash to the Max points out that string theory is literally like playing a sad song on the world's smallest violin.


20181107: Why String Theory is Right
 03:24: Let's actually start with the regular old point particles of the standard model.
 03:29: When a point particle is moving through space and time it traces a line.
 03:55: But in very strong gravitational interactions, that intersection itself becomes more and more point like.
 04:02: The energy density at that point becomes infinite.
 04:22: OK, let's switch to string theory where particles are not points.
 04:48: The vertex is no longer point like.
 04:51: It can't be point like.
 05:06: ... gravity isn't hopelessly broken in string theory, and that's a huge point in favor of string theory, but these world sheets will also help us see ...
 05:20: And this is the second point in string theory's favor.
 06:31: It quantizes the equations of motion of slowmoving, pointlike particles.
 08:19: ... the location of the peaks and valleys in different ways at different points in space without screwing up the ...
 13:30: Philosophical points to consider as we continue to follow the mathematical beauty hopefully towards an increasingly true representation of spacetime.


20181031: Are Virtual Particles A New Layer of Reality?
 00:53: Sometimes our mathematical hacks point to strange new aspects of reality.
 06:32: Bizarrely, that includes photons that are pointing in the wrong direction to even make the journey.
 06:39: Their momenta are pointing from positron to electron rather than electron to positron.
 06:45: And you also count photons emitted by the positron but pointing away from the electron.
 07:57: It can move between our electron and positron even if its momentum is pointing in the wrong direction.
 08:52: ... into and out of existence, the socalled vacuum fluctuations or zero point ...
 09:41: This leads to a nonzero average energy called, confusingly, the zero point energy.
 10:00: Or more to the point, do vacuum fluctuations produce actual particles when there's nothing else around?
 10:19: It has a constant zero point energy.
 10:42: This is a pretty subtle point, but it makes a huge difference in how we think about the vacuum.
 14:23: Any and, perhaps, all of these may be true but that misses the point.
 14:28: ... point is that the overwhelming majority of every civilization that ever ...
 15:32: Paper Dragon points out that not enough attention is paid to one particular possible great filter.
 15:42: It's a good point because we have very little capacity to assess the likelihood of that transition.
 16:15: A lot of that time, life was evolving towards the point that it could become intelligent.
 16:48: A few of you pointed out that our depiction of the binary star system was wrong.


20181025: Will We Ever Find Alien Life?
 06:32: That still seems surprising given those 40 billion possible starting points for life in the Milky Way.
 11:02: ... Cooper and John [INAUDIBLE] point out that the technology needed to create an extinction level event will ...
 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.
 13:54: ... theory has only one tunable parameter, Michael Murphy sarcastically points out that 10 to the power 500 is a little larger than ...
 16:16: Eduardo Martinez makes an interesting point.


20181018: What are the Strings in String Theory?
 09:31: String theory fixes this because the graviton is a loop, not a point particle.
 14:43: A few of you pointed out that a black hole computer couldn't store the information about other black holes, and you're right.


20181010: Computing a Universe Simulation
 07:16: For example, a simple quantum system would be a group of electrons with spins pointing up or down, corresponding to a single bit the information each.
 07:59: This follows a paper by Seth Lloyd that I pointed you to in the challenge question.
 14:06: ... constraints on the way the universe can behave." It's such a good point. ...


20181003: How to Detect Extra Dimensions
 14:57: ... e.g., by dropping it into a black hole, is an interesting philosophical point. ...


20180920: Quantum Gravity and the Hardest Problem in Physics
 14:35: dabeste points out that it's important to emphasize that you're talking about the observable universe, not the entire universe.
 15:01: VoodooD0g points out that the vacuum isn't really empty, what, with all the virtual particles popping into and out of existence.


20180912: How Much Information is in the Universe?
 01:44: ... the main point, the really weird, surprising point, is that the maximum amount of ...
 04:12: You might argue that more than one bit can fit at each grid point in the universe.
 04:21: ... will be better to use the number of grid points in a quantum phase space, which includes position, but also other ...
 12:36: Patrick Dunn offered a very reasonable clarification of a point that I rushed over.
 12:51: Patrick points out that what I should've said was that they couldn't induce a second peak of gas release from the same samples.
 14:35: So the halflife is the amount of time it takes for something to have a 50% chance of decaying at some point during that time.
 15:35: Marco Dalla Gasparina points out that The Nothing can be defeated with the help of the Luck Dragon.
 16:00: Valid point.


20180905: The Black Hole Entropy Enigma
 02:08: From the point of view of the outside universe, black holes can only have three properties mass, spin, and electric charge.


20180830: Is There Life on Mars?
 10:23: Perchlorates act as antifreeze, lowering the freezing point of water.
 12:16: With enough of this stuff, the freezing point of water could be as low as negative 75 Celsius.


20180823: How Will the Universe End?
 03:48: So at this point in the universe's future history, the Age of Stars has passed and no starlight will ever shine again.
 11:04: This possibility was also pointed out by Freeman Dyson.
 11:49: At this point, there's really no hope for extracting useful energy from the universe.
 15:20: Epsilon Jay asks why electrons are thought of as infinitesimal points.


20180815: Quantum Theory's Most Incredible Prediction
 03:53: As far as we know, electrons are pointlike.
 03:57: And it doesn't really make sense to think of an infinitesimal point as rotating.
 04:49: Thinking of electrons as little bar magnets or as rotating balls of charge is a nice starting point.
 05:38: Experiments point to this but so does the Dirac equation.


20180801: How Close To The Sun Can Humanity Get?
 04:00: It will also measure the outward flow of the magnetic field through the pointing flux, as well as the plasma density and electron temperature.
 12:10: Which is this a number of very reasonably point out that the demon or device doesn't really need to remember anything to do its job.


20180725: Reversing Entropy with Maxwell's Demon
 07:34: From our point of view, the randomness of the particles decreases, but that randomness is transferred to the memory of the demon.
 07:45: At some point, the system for sorting particles needs to be reset to continue its work.


20180718: The Misunderstood Nature of Entropy
 05:18: So if you look at the system at some random point in time, it'll be in a completely random microstate chosen from all possible microstates.
 08:14: For example, if we try to draw pictures or write words in phase space, this is where we get to a point of common confusion.


20180711: Quantum Invariance & The Origin of The Standard Model
 01:35: ... the earth for the equations of motion of the ball, the altitude zero point is ...
 04:51: And it's analogous to transforming our altitude zero point up or down by the same amount everywhere.
 05:32: A global phase shift looks like this, where all points move by the same amount.
 05:38: ... if we do a local phase shift, say, only this point here, only that location changes, as if it were part of the shifted ...
 05:50: If you allow this sort of local phase shift, you can change each point in a different way and really mess up the wave function.
 08:53: At this point, we only need a couple of extra steps to produce the full description of electromagnetism in the quantum world.
 11:53: Richard Brockman and badly drawn turtle point out the danger of combining multiple experiments to increase the significance of your results.
 12:46: A few of you point out that if you build a wall of lead, one likely, you'd think, to try to stop neutrinos, you would just collapse into a black hole.


20180704: Will A New Neutrino Change The Standard Model?
 02:10: ... quantum chirality and the Higgs mechanism, and finally, why all of this points to sterile ...
 11:53: ... is actually destroyed, then the rewind would get stuck at the point of information destruction because the universe wouldn't know which of ...


20180620: The Black Hole Information Paradox
 04:11: And when Hawking first pointed out the paradox in the mid70s, physicists were skeptical that there was a real problem.
 06:07: The motivation for this idea is the fact that, from the point of view of an outside observer, nothing ever actually crosses the event horizon.
 07:14: Let's start with the second point.
 07:25: From the point of view of an observer falling into the black hole, they aren't frozen at the horizon.
 08:52: Rather, it distorts the horizon, creating a sort of lump at the point of crossing.
 13:37: That's a universe of weirdness that we'll do an episode on at some point.


20180613: What Survives Inside A Black Hole?
 00:16: ... the result of absolute gravitational collapse of a massive body, a point of hypothetical infinite density surrounded by an event ...
 03:38: We can think of the gravitational field at any point as being caused by the gravitational field at surrounding points.
 03:45: Each point on the rubber sheet doesn't actually see the source of the gravitational field.
 05:12: The mass could all be located at a single point within the surface or could be evenly distributed across that surface.
 06:37: ... comes from the fact that if you draw increasingly large spheres around a pointlike field source, the intensity of those forces gets spread out over an ...


20180523: Why Quantum Information is Never Destroyed
 01:43: For example, if the equations stay the same from one point in time to the next, then energy is conserved.
 02:23: ... if its equations of motion allow us to perfectly predict the starting point simply by knowing the state of the system at any later ...
 02:38: ... if knowing the exact state of every particle in the universe at one point in time allowed us to calculate its exact past history at all ...
 02:50: That would mean that the exact configuration of the universe at any point in time defines the exact configuration at any other point.


20180516: Noether's Theorem and The Symmetries of Reality
 03:47: On the other hand, the gravitational field across the whole stretch of road doesn't change from one point in time to the next.
 06:24: It's a generalization of Fermat's principle, which states that light will always take the path between two points that minimizes the travel time.
 11:49: ... from each star spreads into neighboring pixels by fitting the socalled point spread ...


20180509: 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.
 09:37: Many of you point out that there will be useful sources of energy in the universe long after the last red dwarf fades away.


20180502: The Star at the End of Time
 06:49: At that point, the night sky will be dark, and only a powerful telescope could reveal the trillion faint red dots scattered across the sky.
 07:03: Individual points of white light will appear in the night sky, shining for up to a few billion years before winking out.
 10:54: Anyway, as Gareth Dean points out, two of those dots were almost on top of each other, so we're all good.


20180425: Black Hole Swarms
 06:11: They spotted 92 pointlike Xray sources within one parsec, or around three light years, of the galactic center.
 10:38: Two gravitational waves crossing paths will add together at any one point in space and time.


20180418: Using Stars to See Gravitational Waves
 10:26: Many of you noticed that we showed a red blood cell with DNA and pointed out that adult red blood cells don't have DNA.


20180411: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)
 00:40: So can we approach the question of the origin and the very nature of life from the point of view of physics?
 01:24: ... in the observable universe being crunched into an infinitely dense point are low ...
 04:19: ... was first pointed out by Ludwig Boltzmann, who described life as a struggle for entropy, ...
 07:28: And at some point, natural selection takes over.
 07:37: Molecules better at that process become more abundant, and at some point, they become true selfreplicators and eventually, they become life.
 11:07: ... Diagrams points out that from the point of view of an inertial observer, an accelerating ...
 11:45: Fernando Franco Felix points out something interesting.
 13:09: On the other hand, during the inflationary epoch in the extremely early universe, the cosmic event horizon was very close to every point.


20180404: The Unruh Effect
 02:38: ... in the past light cone can reach our observer either at the current point or at some point in their past world ...
 04:03: ... I fire a photon at the point of closest approach, say to send a message, that photon can never catch ...
 04:43: They also stay ahead of any photon emitted from this diagonal line or any point on the other side of it.
 06:53: This is because that distant point of spacetime is smoothly connected to the spacetime near the horizon.
 10:42: Right now I have to jet but not too fast, lest I combust in a FullingDaviesUnruh thermal bath as I accelerate to that future point in spacetime.


20180328: The AndromedaMilky Way Collision
 08:21: At this point, the sun will already have expanded into a red giant.
 10:00: Patrick Hogan points out that it's more accurate not to think about dark matter as a thing.


20180321: Scientists Have Detected the First Stars
 06:55: At both of these points, the weight is momentarily still.
 07:27: That means the projectiles kinetic energies at the point of impact must also be the same.
 08:07: Then, subtract the potential energy of the projectile at its point of impact, and we have its kinetic energy.


20180315: Hawking Radiation
 09:09: Not from specific points on the event horizon.


20180307: Should Space be Privatized?
 02:58: Well, at some point both Dragon and Dream Chaser are expected to carry actual people to the ISS, and perhaps beyond.
 11:48: ... that point, the whole thing becomes a white dwarf, but without the dramatic cycle of ...


20180228: The Trebuchet Challenge
 01:25: More, it doesn't actually matter what path the object takes between two points under the influence of that force.
 01:31: The change in speed for a given object will be the same as long as the start and end points are the same.
 01:59: ... of kinetic energy that will be gained or lost by traveling between two points, then we can keep track of the potential for future gains or losses of ...
 06:59: All that good lever action swings a 90kilogram stone from ground level, releasing it at some point in the upward arc.
 07:10: ... counterweight swings to a lowest point 1 meter above the ground and continues its arc, ultimately rising to a ...
 07:32: The really surprising thing about this problem is that you don't need to know the lengths of the arms, the release point of the ball, or any of that.


20180221: The Death of the Sun
 08:47: ... moons may be a final temperate vantage point to watch the sun's inevitable death, and to look to the greater galaxy ...
 10:18: ... a certain point, after a threshold, they come into range of each other's strong nuclear ...
 10:59: It represents the energy exchange that would result from a particle or system moving between two points under the action of a conservative force.
 11:07: It tells you the kinetic energy that will be gained or lost in motion between two points due to the work done by that force.
 11:21: But potential energy doesn't have an absolute zero point.
 11:25: That said, there are conventions for those zero points.
 11:27: ... a falling object, we tend to take the ground as the zero point, but we could equally make it the center of the Earth or a point ...


20180214: What is Energy?
 04:19: That's true even if the gravitational acceleration changes from one point in space to the next.
 04:53: ... an object travels between two different points in a gravitational field, it will always experience the same conversion ...
 05:07: ... path taken between two points within a conservative force field takes the same amount of work, the ...
 12:58: ... Brockman points out that 15 Earth masses of terrestrial material is a lot a planet for a ...
 14:02: ... Elytron points out the ridiculousness of astronomers calling all elements heavier than ...


20180131: Kronos: Devourer Of Worlds
 08:52: Mark points to a paper Korycansky, Laughlin, and Adams, 2000 that proposes a method to do just this.
 09:34: TheRealMirCat points out that if Earth is our only home by the time all of this happens, we deserve to burn.


20180124: The End of the Habitable Zone
 01:43: At that point, the sun had plenty of hydrogen fuel.
 05:36: ... the geological evidence is called the faint young sun paradox, and was pointed out by Carl Sagan and George Mullen in the early ...
 08:14: ... much more able to adapt as surface temperature approaches the boiling point of water and atmospheric CO2 ...
 09:15: But perhaps we'll have advanced to the point of being able to replenish the Martian atmosphere by then.
 11:50: [INAUDIBLE] makes a good point about the pop sci explanation of Hawking radiation.


20180117: Horizon Radiation
 04:35: A particle perfectly localized in space a single spring or a single point on the drum skin.
 04:52: Now every point in this field, this drum skin is connected to neighboring points.
 06:24: Now, each one of these momentum modes exists at all spatial points in the universe.
 06:51: One particle at one point in the universe.
 10:06: ... part of the skin in a very different way, with different forces at each point. ...


20180110: What Do Stars Sound Like?
 02:07: While the distance stars are infinitesimal points of light to even our best telescopes, the surface of the sun can be resolved in incredible detail.
 11:02: He points out that they say the Earth's surface would be incinerated by such an event.


20171220: Extinction by GammaRay Burst
 01:33: At five or six different points in time over the past half billion years, a large fraction of species simply vanished from the fossil record.
 07:04: Unfortunately there is no way to tell whether a GRB will be pointed our way until it happens.
 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.
 12:44: Timothy Judge points out a significant potential error in the paper by Portegies Zwart and collaborators.


20171206: Understanding the Uncertainty Principle with Quantum Fourier Series
 05:01: Is it even possible to make an instantaneous spike at one point in time out of a bunch of sine waves that themselves extend infinitely through time?
 05:12: ... to get a spike at one point in time, you need to use infinitely many different frequency sine waves, ...
 08:12: ... Born rule tells us how likely we are to find the particle at any given point when we make a ...
 08:38: So if we measure a particle's position, then from our point of view, it's wave function is highly localized in space.
 12:31: ... thanks to everyone who pointed out the editing error at the end of the Suicide Robots episode, where we ...
 13:30: A couple of you pointed out a better alternative.
 14:17: Regarding our zero point challenge answer, Jaden Andrews asked how to prevent the gecko's tail falling off when you harness them for wall climbing.
 14:32: ... a couple of you pointed out, we already assumed the geckos had zero mass, so who's to say those ...


20171129: Citizen Science + ZeroPoint Challenge Answer
 01:52: These exploding stars show up as transient point of light, typically in very distant galaxies.


20171122: Suicide Space Robots
 04:12: But at that point, the little rover had lasted 25 times its original mission plan.
 10:57: ... and impressively several other people pointed out that the first gecko we showed is a leopard gecko, which is one of ...
 11:41: Doctor diagrams, I cede most of your points.
 11:58: Let me quickly address your main point.
 12:32: That's the main point.
 13:00: A few of you point out that the EM drive now has a peer reviewed paper coming from Harold white at NASA's Eagle Works Laboratories.
 13:41: ... that brings the other point that a few of you raised the idea that rejecting ideas like the ...


20171102: The Vacuum Catastrophe
 00:51: ... there's a quantum fuzziness in the amount of energy contained at every point in space a nonzero zero point energy in the quantum fields that can ...
 01:30: From the perspective of quantum field theory, every point in space is represented by a quantum oscillator, one for each elementary particle type.
 02:09: ... describe a perfect vacuum, every single possible frequency mode at every point in space must have that amount of ...
 04:20: The zero point of the energy scale is irrelevant.
 04:31: ... going to come back to that point in an upcoming episode, so you'll be able to knowledgeably scoff at zero ...
 04:47: Just redefine the zero point to whatever you want, and you're good to go.
 06:07: ... some fields can have extremely large positive zero point energies, then perhaps others have extremely large negative zero point ...
 07:59: ... energy of exactly 0 if we assume symmetry of positive and negative zero points between different fields, but a very small nonzero vacuum ...
 08:19: Gigantic positive and gigantic negative zero point energies would need to cancel each other out down to a very tiny nonzero value.
 08:38: ... extremely rare universe whose fundamental fields canceled out their zero point energies, at least enough of them to allow life and astronomers to ...
 10:55: ... X asked whether it's possible to tap into the zero point energy or dark energy, like with the zero point modules in "Stargate." ...


20171025: The Missing Mass Mystery
 11:02: Last week, we talked about virtual particles, zero point energies and the nature of nothing.


20171019: The Nature of Nothing
 08:20: ... particles popping into and out of existence, then the socalled zero point energy of those fields should not be ...
 12:56: The point at which a substance changes phase depends on both temperature and pressure.
 13:06: ... there are way higher than the atmospheric pressure evaporation point of ...
 15:47: The Simulacra notes that physics has reached the point where it's working on nothing at all.


20171011: Absolute Cold
 00:42: This state of absolute cold is the zero point in the Kelvin temperature scale corresponding to negative 273.15 Celsius.
 06:14: All the quantum systems also have nonzero zero points, and that leads to even strange phenomena.
 06:31: And some quantum fields have an intrinsic nonzero zero point before even bringing Heisenberg into it.
 07:53: We never would've guessed we'd reach this point when we started making Space Time early in 2015.
 09:53: ... Gamble points out that if this binary pair is a whole light year apart, then for us to ...


20171004: When Quasars Collide STJC
 06:41: Both knots have the classic energy distribution of a completely independent jet launching point.
 08:19: One possibility is that gas can provide the needed friction beyond that point.


20170928: Are the Fundamental Constants Changing?
 05:13: And these electrons have spins pointing in opposite directions.
 07:45: This is intriguing, but get this the researchers then pointed the very large telescope in Chile at a different part of the sky.


20170920: The Future of Space Telescopes
 07:41: ... Pointed outwards, it could spot a terrestrial planet at tens of light years ...


20170913: Neutron Stars Collide in New LIGO Signal?
 05:29: They last a lot longer, at least from LIGO's point of view.
 10:35: ... last LIGO observing run ended on August 25, at which point they announced that there were "promising candidates." Probably that ...
 14:47: Regarding our episode on white holes, a few of you wanted some clarification of a point I made.
 15:00: What I mean by that is that the Big Bang happened everywhere at once, not at an infinitesimal point in space.
 15:21: But for the Big Bang, that density is everywhere, not concentrated at a single point, as in the case of the white hole.
 15:29: BrendanBlake42 points out that Karl Schwarzschild looks like Simon Pegg in a comedy mustache.


20170830: White Holes
 02:31: ... Schwarzschild solved its equations for a very particular case a single point of mass in an otherwise empty space ...
 04:20: From the point of view of the outside universe, the eternal black hole singularity exists both in the infinite future and in the infinite past.
 08:11: The past singularity and past event horizon are infinitely far in the past from our point of view.


20170824: First Detection of Life
 07:33: This only happens for transiting exoplanets, those that happen to be aligned so that they pass in front of their parent star from our point of view.


20170816: Extraterrestrial Superstorms
 12:54: Make each turning point at a different time so the zigzags are uneven.
 13:13: Vacuum Diagrams points out that two diagrams are missing from the challenge answer.
 13:35: YouTube Account points out that the perfect name for dark flow isn't WTF flow, but rather what the flow.


20170810: The OneElectron Universe
 02:20: Wheeler's notion was that if electrons behave as though they are identical, perhaps they truly are, to the point of being identically the same entity.
 02:34: It exists as a line traced by its passage through space and time, rather than as a pointlike particle at one instant in time.
 02:41: The pointlike electron is just a segment of that worldline if we take a slice through space time at one instant in time.
 03:09: At any one point, there can be multiple instances of the same electron.
 07:30: At some point in the middle of the diagram, we see many, many electrons.
 10:59: ... galaxies in the observable universe are drifting very slightly towards a point beyond the cosmic ...
 12:04: ... if all galaxies have a slight preferred direction to one point on the sky, then the way those velocity vectors map onto our line of ...


20170802: Dark Flow
 01:05: ... across the cosmos may be moving ever so slightly towards the same point beyond the cosmic ...
 05:38: It's like a lot of the matter in the universe is flowing toward some point beyond the edge of our universe.
 10:04: ... couple of you pointed out that the Feynman diagram vertex, representing interactions between ...


20170726: The Secrets of Feynman Diagrams
 00:19: ... properly calculate the probability of a particle traveling between two points, we need to add up the contributions from all conceivable paths between ...
 02:19: In Feynman diagrams, we depict the electron as an arrow pointing forwards in time, while the positron is an arrow pointing backwards in time.
 02:59: Particle/field interactions are represented as a vertex, a point where the lines representing the different particles come together.
 03:08: ... that there's only one vertex that's possible in QED one with an arrow pointing in, an arrow pointing out, and a single photon ...
 08:12: This last point is bizarre, but really powerful.
 13:09: Well, good point.
 14:07: ... points out what was perhaps the greatest tragedy in the entire sorry history of ...


20170719: The Real Star Wars
 02:22: ... technology quickly developed to the point that a single missile could deliver multiple nuclear warheads several ...


20170712: Solving the Impossible in Quantum Field Theory
 03:58: ... the quantized fueled excitation of the photon, and the connecting points, the vertices, represent the absorption and emission of the ...
 14:10: [INAUDIBLE] points out that the final probability for a particle journey is the square of the length of the complex probability amplitude vector.
 14:37: ... also correctly points out that the individual paths don't have different probability amplitude ...
 14:52: ... points out that the wildly divergent paths would require superluminal speeds to ...


20170707: Feynman's Infinite Quantum Paths
 01:27: ... defines the probability of that particle actually showing up at a given point on the ...
 03:09: ... this to know the likelihood of a particle traveling between two points, A to B, we need to take into account all of the conceivable ways that ...
 06:52: But if two parts contribute individual probability amplitudes that point in exactly opposite directions, they cancel each other out.
 08:50: See, when I say there are lots of ways for a particle to travel from point A to B, I mean lots.
 09:07: ... example, a photon traveling between two points could spontaneously become a virtual electronpositron pair before they ...
 14:06: ... points out that if matter and antimatter particles are always created in pairs, ...
 14:13: Well, good point.
 14:24: At some point, it became cool enough for this process to stop.


20170628: The First Quantum Field Theory
 01:18: ... particles as vibrational modes in fundamental fields that exist at all points in space and time through the ...
 02:22: ... any point in time, every point on a vibrating string is displaced by some distance ...
 02:59: Every point in space has some displacement in some imaginary extra direction analogous to but not the same as a fourth dimension.
 03:16: ... an equilibrium value, which is just the average density, but at every point in the room, a sound wave can cause air density to oscillate to higher ...
 07:22: He imagined each point in space as being an oscillator.
 07:31: ... oscillation at each point can be complicated but it has to be built up from a number of minimum ...
 13:33: ... Diagrams points out that Schrodinger himself did write down a relativistic version of ...
 13:50: ... Mr. Diagrams points out, the resulting Klein Gordon equation gives negative energy solutions ...


20170621: AntiMatter and Quantum Relativity
 02:55: The axis of spin can point in different directions; for example, up or down.
 04:05: ... spin and the up and down degrees of freedom were the direction of pointing of the angular momentum ...
 12:32: A few people point out that there are lots of cold spots in the CMB map and that some look larger than the actual cold spot.
 12:40: ... first, let me point out that the cold spot wasn't identified by the, "oh, that bit looks a ...


20170607: Supervoids vs Colliding Universes!
 06:03: ... of galaxies in the direction of the cold spot all the way out to the point where dark energy started to dominate the ...
 08:58: It's a whole big topic, and we'll do an episode on it at some point.
 09:18: At that point, it stops inflating and starts expanding normally.
 10:01: If that merger point is distant from us, then this looks like a hot or cold spot in the cosmic microwave background.


20170531: The Fate of the First Stars
 07:17: At that point, the contraction is much slower, and those cloud fragments become stars.
 11:35: Better & Better points out that martian humans may evolve their own microbes that would be deadly to humans.
 12:53: In fact, as SalemSays, and several of you, point out that direct genetic manipulation probably will happen.


20170517: Martian Evolution
 00:47: At some point, perhaps soon, perhaps in the far future, we will try to colonize Mars.
 09:06: At that point, we consider the populations to be separate species.


20170510: The Great American Eclipse
 11:02: ... of you pointed out that Neil deGrasse Tyson has actually argued against the simulation ...


20170503: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson
 00:06: ... games become more and more lifelike, it's becoming clear that at some point, perhaps soon, our simulations will be indistinguishable from ...
 03:20: But he's illustrating a very serious point.
 10:22: Bostrom himself points out that, upon being found out by one of its resident minds, the simulation can be instantly edited or rewound.
 14:32: Henry School follows with a very good point on these emergent forces.
 14:36: ... just the improbability of the directions of their motion happening to point to that ...


20170426: Are You a Boltzmann Brain?
 06:58: We observe the universe from as typical a vantage point as is consistent with our experience.
 09:23: This is a cute philosophical point.


20170405: Telescopes on the Moon
 04:23: When exposed to the sun, temperatures rise to around 125 Celsius, well, above the boiling point of water.
 06:50: The caveat is that it only points straight up.
 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.
 08:02: It's a cosmologists dream, especially because cosmology tends not to require complex pointing.
 11:44: So there should be a point inside such a black hole where this antigravity perfectly balances regular gravity, and it's possible to float.
 12:34: He points out correctly that it's only the radial component that becomes timelike.


20170329: How Time Becomes Space Inside a Black Hole
 06:26: At this point, it's time we switch diagrams.
 08:05: As we fall with the faster than light flow of space time, we overtake light that is outward pointing.
 08:39: Also in our past light cone are light rays that are pointed inwards, some of them coming from the outside universe.
 09:26: But remember that future light cone actually just points towards the singularity.
 11:51: At this point, the use of the term is pretty loose.


20170322: Superluminal Time Travel + Time Warp Challenge Answer
 01:54: ... entire universe exists simultaneously in a state of now, and that all points move forward in time at a constant rate for all observers, governed by ...
 05:47: And now that you've mastered fasterthanlight travel, can you pilot the Paradox back to a point before the race even started?
 06:15: These are the spacetime intervals as calculated from the zero point in space and time, the beginning of the race.
 08:22: Well, no, not if we can find a way to bring the Paradox back to a point in space before it was built.
 08:30: To do that, we first need to outrace photons that were admitted at the space time point that we want to perceive.
 09:53: Superluminal paths aren't real worldlines Real worldlines don't point backwards in time under Lorentz transformations.


20170315: Time Crystals!
 06:39: At that point, thermal effects take over and the rhythm dies.
 12:03: ... think my favorite comment was from WarriorofCathar, who pointed out that we basically just learned all about a solar system light years ...


20170308: The Race to a Habitable Exoplanet  Time Warp Challenge
 00:18: In fact any FTL ship set on the right trajectory can find its way back in time to a point before its journey began.


20170301: The Treasures of Trappist1
 03:40: However, that's really hard to predict at this point.
 07:16: Finally, I mentioned tidal heating could warm TRAPPIST1h above water's freezing point.
 10:11: Aaron Craig points out that Galileo did not, in fact, invent the telescope.


20170222: The Eye of Sauron Reveals a Forming Solar System!
 03:52: At this point, it's a planetesimal at about a kilometer in diameter.
 07:48: ... some critical point, it may have interacted with another massive planet in the system, ...


20170215: Telescopes of Tomorrow
 01:16: Webb will begin unfolding its 18 hexagonal mirrors on its journey to the sunearth system's second Lagrange point about a million miles away.
 03:23: A single point, like a star, will always be a little bit blurred when it reaches our camera.
 05:40: We can think of light from a very distant pointlike object say a star as reaching us as a series of wavefronts.
 05:47: Our eyes and our telescopes can focus those wavefronts back into a point.
 05:52: With perfect focus, we can reconstruct every point on the sky, creating a perfect image.


20170202: The Geometry of Causality
 01:23: ... I need to travel to a neighboring star shrinks dramatically from my point of ...
 05:15: ... from my stationary point of view, I define my xaxis as a long string of spacetime events at ...
 05:28: To observe those points, I just wait around until their light had time to reach me.
 05:44: Our traveler does the same thing, but from my point of view, their clock is slow, so I see them register signals at a different rate.
 06:40: In fact, we grid up the diagram with a set of lines parallel to these new axes and square up everything while maintaining our intersection points.
 07:45: ... delta x and delta t of the event at the end point of a traveler's world line might change depending on who is watching, ...
 08:50: From the point of view of a particle communicating some causal influence, those points are equivalent.
 09:33: There's no point anywhere downhill that I can't reach as long as I can get close enough to the speed of light.


20170125: Why Quasars are so Awesome
 01:49: When the very first radio telescopes pointed to the heavens, they saw fat blobs of radio light, whose sources were unknown.
 02:38: That timing allowed astronomers to identify a tiny starlike point of bluish light as the source of the radio emission.
 05:48: Oh, and if one of these jets happens to be pointed directly at us, then we see strange effects due to the near light speed motion of the jet material.


20170119: The Phantom Singularity
 00:04: The point of infinite density at the core of a black hole, but also so much more.
 01:30: That means all of that object's mass would need to be concentrated at that center, a single point of 0 size, which means infinite density.
 02:23: It's really just any point that causes problems.
 02:26: Commonly these problematic points are where quantities become bigger and bigger approaching infinity as they do near a black hole.
 03:44: Actually, Einstein himself agreed on this point.
 05:17: The Schwarzschild metric allows us to compare two points or events in space time around a massive object from the perspective of different observers.
 07:40: At that point, the entire equation starts behaving very badly.
 08:12: The entire space time interval for a nonmoving point at the event horizon is 0.
 11:14: But can that point of infinite density really exist?
 12:36: ... he pretty much obliterated the entire white hole hypothesis by correctly pointing out that if they existed in any great numbers, we would see ...
 14:25: Aaron Schofield points out that even if the EM drive produces only a tiny thrust, it's still interesting.


20170111: The EM Drive: Fact or Fantasy?
 02:49: He pointed out that it's like trying to accelerate a car by getting in the driver's seat and pushing on the windshield.
 11:09: SunPower Guru argues that SITI is pointless, because there's no good reason to think that aliens would use, for example, radio.
 11:49: But that's only useful to a point.
 12:54: But as Gareth Dean points out, lasers suck for broadcast, so sending a signal broadly.


20170104: How to See Black Holes + Kugelblitz Challenge Answer
 06:13: You can think of the verticalish lines as representing points in space that are a constant distance from our center point.


20161221: Have They Seen Us?
 08:42: Loeb and Zaldarriga's numbers assume pointing SKA at a target star system for an entire month and adding up all of the radio emission over that time.
 10:31: ... the SETI Institute's John Billingham, along with James Bedford, point out, that one month integration time requires a very consistent narrow ...
 11:33: ... TV bubble would be spotted within hours, or even minutes, of aliens pointing the facility to our solar system, even if they weren't looking for ...
 14:05: And so light that the monkey emitted from below that point is trying to go up, but is actually going downwards.
 16:59: The correct way to get this number is by using general relativity to find the point where the flow of spacetime reaches the speed of light.


20161214: Escape The Kugelblitz Challenge
 01:30: At the very least, even a Schwarchild black hole must have formed at some point.
 01:58: There is a specific size that represents the point of no return for this collapse.
 05:06: At that point, it will look exactly like a black hole from the outside.


20161208: What Happens at the Event Horizon?
 01:38: For example, are objects falling through the event horizon really physically frozen there from the point of view of the outside universe?
 03:10: It has a point of infinite density, the singularity, and an event horizon a bit further out.
 09:17: Even if we do travel at the speed of light, after a certain point there's no catching the monkey.
 14:50: ... given that the particles supposedly all start at exactly the same point. ...
 15:02: Well, the simple answer is that the particles don't start at exactly the same points.
 16:16: Vacuum Diagrams correctly points out that to know the future trajectory of a particle, you only need position, not velocity, as I had stated.
 16:29: ... for the correction and thanks also for pointing out those extremely interesting papers that detail certain failings of ...
 17:15: ... first, as was pointed out to me in a nice email by physicist and science writer Adam Becker, I ...
 18:25: ... and so derived the simpler description in which the particle is pointlike. ...


20161130: Pilot Wave Theory and Quantum Realism
 03:59: This wave guides the motion of a real pointlike particle that has a definite location at all times.
 04:51: ... random if you know the exact particle position and velocity at any point, you could figure out its entire future ...
 09:25: So a measurement at one point in the wave function will affect its shape elsewhere.


20161116: Strange Stars
 07:40: ... 1,000 years later, after some small technological advancements, we pointed our radio telescopes and then the orbiting Chandra Xray Observatory to ...


20161109: Did Dark Energy Just Disappear?
 09:38: ... you to another vid for details on universe geometries, but the main point is that we can also figure out where we should be on this graph by ...
 14:03: My point is that there are plausible options, and a giant rotating maglev ring city in a sealed taurus is actually plausible.


20161102: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers
 01:07: ... So, changes in the shape that don't break any connected neighboring points. ...
 01:33: ... particles tend to line up, but you get these little twists at certain points: a vortex around which the spin ...
 07:13: The Kepler Observatory points only in one direction, so those stars are spread along a column a few thousand light years long.


20161026: The Many Worlds of the Quantum Multiverse
 01:09: But to summarize, a stream of photons or electrons, or even molecules, travels from some point to a detector screen via pair of slits.
 03:22: And from its point of view, is the physicist outside also a quantum blur until the box is opened?
 08:56: But another point of resistance must be the overwhelming existential crisis induced by the idea of nearinfinite versions of one's self.


20161019: The First Humans on Mars
 02:19: Anything less would defeat the main point to be a safeguard against our extinction.


20161012: Black Holes from the Dawn of Time
 02:06: It reveals tiny differences in the density of matter from one point in space to the next.
 03:00: ... possibility of many models that some of these fluctuations were, at some point in the early expansion, intense enough to resist the local expansion of ...
 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.
 12:50: Liquid methane is just not as good on any of these points.
 12:54: ... criticized my pluralization of "octopus." I said "octopi." Some of you pointed out that it should be "octopuses." First, English is a fluid language, a ...


20160929: Life on Europa?
 11:50: ... and a couple of others point out that John Stewart Bell had another possible solution to this whole ...


20160921: Quantum Entanglement and the Great BohrEinstein Debate
 04:17: ... thought that every special point in the universe must be real and physical and defined by knowable ...
 05:23: That axis can point in any direction.
 08:36: The instantaneous influence has been observed over many kilometers at this point.
 11:41: Daniel Oberley and others point out that a Von Neumann probe may be in our solar system, but be well hidden.


20160914: SelfReplicating Robots and Galactic Domination
 01:52: Today I want to argue that even if these points are true, there are reasons to expect a galaxy full of the evidence of past technological life.
 06:09: At some point, the assembler starts building new Von Neumann probes which, one by one, launch to new, more distant star systems.
 07:46: ... still means tens of thousands of planets in our galaxy get tech at some point. ...
 09:35: In any universe that produces intelligence, someone, somewhere, at some point has to ask, why are we alone?
 11:22: A couple of you pointed out that the Dyson swarm proposal is both ridiculous and nowhere near close to being logistically possible yet.
 11:51: Yeah, good point.


20160824: Should We Build a Dyson Sphere?
 00:53: ... our search for extraterrestrial intelligence, appearing only as strange points of infrared lights but otherwise black at visible ...
 09:52: I guess it couldn't hurt to point some radio telescopes, to look for power leakage from the Kugelblitz swarm.
 11:43: A few of you pointed out that an important bit of info was emitted from the description.
 11:49: Now, we did this because we wanted to expand on that point through last week's challenge question.
 11:57: ... point is that in order to resolve the photon distributions at the screen, you ...


20160817: Quantum Eraser Lottery Challenge
 02:44: ... device that can not only send information instantaneously between two points, but can also send information back in ...


20160810: How the Quantum Eraser Rewrites the Past
 01:29: At that point, the Copenhagen interpretation tells us that a true transition happens between wave and particle.
 02:08: We'll talk about what observation really means at a later point.
 02:12: But it's still pretty interesting to see what happens if we try to observe the wave function at different points in the double slit experiment.
 12:15: A few of you pointed out that I neglected to mention certain known ends of the world that are coming in the distant future.


20160727: The Quantum Experiment that Broke Reality
 04:03: Each photon dumps all of its energy at a single point.
 04:31: It knows the interference pattern of a pure wave that passed through both slits equally and it chooses its landing point based on that.
 05:37: It looks like a wave of possible undefined positions that at some point, for some reason, resolves itself into a single certain position.


20160720: The Future of Gravitational Waves
 02:56: It's the same very wellunderstood tech that we use to process radar signals and at this point, we have a lot of confidence in how this works.


20160706: Juno to Reveal Jupiter's Violent Past
 00:14: ... is the second most important planet in the universe, at least from our point of view, and it holds the secrets to the formation of the solar ...
 02:51: The center of mass of the sunJupiter system lies just above the solar surface, and both the sun and Jupiter circle this point.
 07:44: The solar system at this point had all its planets eight, maybe nine of them but also a huge amount of left over junk.
 08:21: At some point, Saturn's orbit once again fell into resonance with Jupiter's, but now two Saturnian orbits to every one Jovian.
 10:38: So many of you, including Neil deGrasse Tyson, point out that the sun is actually white and not yellow.


20160615: The Strange Universe of Gravitational Lensing
 08:00: The lightspeed flow of spacetime at the event horizon results in old light paths pointing inwards.
 10:05: ... because to properly tunnel, you need to spontaneously find yourself at a point in your wave function that has an equal or lower energy state than your ...


20160608: New Fundamental Particle Discovered?? + Challenge Winners!
 04:16: There's no point choosing between these options until we verify the results.
 04:32: At that point, the signal will either solidify or vanish, assuming no more attacks by cute animals.
 09:44: So at that point in the past, we know that this equation is true.
 13:08: Is there something about the tipping point between the dominance of matter versus dark energy that makes the universe more hospitable for life?


20160601: Is Quantum Tunneling Faster than Light?
 07:39: At that point, you can get an incredibly precise measurement of any differences in photon travel time.


20160525: Is an Ice Age Coming?
 02:46: ... the absolute maximum eccentricity, Earth's most distant point from the sun the Aphelion is about 30% further than the closest ...
 03:31: Two, the pointing of Earth's axis precesses.
 09:40: So over 10,000 to 12,000 years, all of that points to cooling.
 10:54: With CO2 now at 400 parts per million, it's higher than at any point in the Quaternary period.
 13:50: Eugene Khutoransky points out that the idea that energy is not conserved in an expanding universe is still pretty speculative.


20160518: Antigravity and the True Nature of Dark Energy
 00:56: Paradoxically, our measurements points a nearperfect flatness.


20160511: The Cosmic Conspiracy of Dark Energy Challenge Question
 00:54: But we're still very near that tipping point.
 02:59: At some point in the past, there was a perfect balance between dark energy and matter.


20160504: Will Starshot's Insterstellar Journey Succeed?
 06:05: Some type of color spectral sensitivity may even point to life signatures on these planets.
 06:40: ... at the other end, Starshot probes need to know where to point the cameras and then beam that info back to Earth with whatever energy ...
 11:03: ... points out that we must need some sort of luminosity reference point before we ...


20160427: What Does Dark Energy Really Do?
 04:40: Now, that actually points to a more dense universe.
 05:04: So measuring a rapidlyexpanding universe in the past points to it having had its gravity brakes on between then and now.
 07:10: However, this accelerating expansion can be explained with the same bit of math, the cosmological constant, pointing to the same physics, dark energy.
 09:04: Currently, there's still enough matter in the universe to influence the expansion rate, but we're already at the point where dark energy dominates.
 09:52: Pravar Parekh points out that we can't really know that the universe is flat because we can only see a small part of it.


20160420: Why the Universe Needs Dark Energy
 01:48: Today, let's look at one of these measurements the geometry of the universe, which points to a discrepancy in the first Friedmann equation.
 08:04: ... universe gets large enough, the density of regular matter will, at some point, drop below that of this vacuum energy, as described by the ...
 08:14: At that point, dark energy will govern expansion.
 08:25: In fact, the universe reached that tipping point pretty recently, on cosmic time scales.


20160413: Will the Universe Expand Forever?
 10:06: ... Rigitano points out that there seems to be this main sequence of elements produced in ...


20160406: We Are Star Stuff
 02:25: ... stuff of your body, of the Earth, of everything you can see, was at one point forged in one of the most cataclysmic events in the ...
 06:21: At this point, we have a huge problem.
 09:10: Recent research actually points to a new possibility that's even more spectacular.
 13:14: mukul gupta asks whether the expansion of the universe will stop at some point.


20160323: How Cosmic Inflation Flattened the Universe
 00:55: ... billion light years from one edge to the other, that those most distant points should never have had time to communicate with each ...
 01:05: And yet, at some point in the distant past, they must have been in contact.
 05:00: ... of light so that most of it appears causally disconnected, at which point inflation stops and regular expansion takes ...
 08:42: And while we know the minimum amount of inflation needed before that stopping point, we don't really know when it began or even if it had a beginning.
 08:56: But it's also possible that inflationary expansion is the default state of the greater universe I should say multiverse at this point.
 09:17: When first conceived, the inflationary period was thought to have started at a particular point after the instant of the Big Bang.


20160316: Why is the Earth Round and the Milky Way Flat?
 03:40: The downward crush of all that weight is resisted because each of those blocks is hard to compress beyond a certain point.
 11:28: See, the Big Bang didn't happen as a sudden presence of energy at some point.
 12:00: ... background radiation today, given that it was all emitted by a single point at the Big Bang?" Well, the answer to this is related to the ...
 12:12: The Big Bang happened everywhere, not at a single point.


20160302: What’s Wrong With the Big Bang Theory?
 01:00: And at that point, the entire observable universe was around the size of a grain of sand.
 02:46: Our theories look really good to that point.
 04:20: See, at this point, general relativity comes into serious conflict with quantum mechanics.
 06:23: ... needs to have been enough time for something to travel between those points to diffuse and even out that ...
 08:09: So 100 trillion trillion to something like our grain of sand size at which point it slowed down to its regular expansion rate.


20160224: Why the Big Bang Definitely Happened
 02:36: ... the entire observable universe was once compacted into an infinitesimal point, a singularity at time t equals 0, the hypothetical instant of the Big ...
 03:05: So we know that at some point in our rewind, pure general relativity will give us the wrong predictions for the behavior of space time.
 03:15: But we understand those limitations really well, and we know that we can be confident in our predictions down to a certain point.
 03:23: ... times after that point, our understanding is good enough to make some pretty bold and testable ...
 03:51: ... today, it hit a critical temperature of 3,000 degrees Kelvin, at which point the entire universe slipped from plasma to gas as the first hydrogen ...
 09:41: ... Mulyk points out that it's kind of weird that Advanced LIGO was turned on just in ...
 10:51: ... Proctor points out that the date cited for the discovery of this black hole merger is ...
 11:30: That's when this merger was seen, as soon as LIGO had fully leveled up to the point that it was actually capable of seeing them.
 12:21: At that point, I won't be so worried about the price of gas.


20160217: Planet X Discovered?? + Challenge Winners!
 07:01: Quasar jets, pointing towards us, appear crazily bright.


20160211: LIGO's First Detection of Gravitational Waves!
 05:22: ... signal, then it may be a clue that the theory is incomplete, or even point to a new, deeper ...
 07:39: Now this is a really good point that I didn't mention.


20160203: Will Mars or Venus Kill You First?
 01:23: ... Point one, due to its small size, it's molten interior has solidified long ...
 01:44: And this is exacerbated by point two, the atmosphere was already only weakly held by Mars' low gravity.
 02:55: The most dangerous thing about the drop in pressure is that the boiling point of liquids also drops dramatically.
 03:21: ... your blood will be leached of oxygen, starving your brain, and at some point blocking blood flow all ...
 03:30: This might take a minute or two to stop your heart, but at which point, you're done for.
 04:21: At this point, you're probably thinking you'll just stay in the nice oxygenated pressurized heated habitat and be fine.


20160127: The Origin of Matter and Time
 08:18: One of them a point on the space time diagram can influence another if a signal can travel between the two.
 11:55: Your timeline remains synced to the timeline of your point of origin.


20160113: When Time Breaks Down
 03:57: So from my point of view, the photon takes longer to make the updown journey.
 04:49: From our point of view, the photon clock could never complete a tick because the photon could never reach that mirror.
 08:52: Joshua Hillerup raises a great point.


20160106: The True Nature of Matter and Mass
 09:06: Felix Feist points out that given that the righthanded electron doesn't have weak hypercharge, shouldn't it be massless?
 09:44: ... by PowerPoint wonders whether there could be a point in space somewhere where the Higgs field takes on the value of zero, and ...


20151216: The Higgs Mechanism Explained
 01:20: Imagine that every point in the universe has a certain level of electronness.
 05:06: While most quantum fields hover around zero in empty space, the Higgs field has a positive strength at all points in the universe.


20151209: How to Build a Black Hole
 05:46: Location remains a possibility cloud until the neutron interacts with another particle, at which point, its location is resolved.
 08:28: At this point, the event horizon actually comes into being.
 09:03: All paths lead to the central point of infinite curvature, the singularity.
 09:09: From the point of view of the star, itself, the inward cascade happens.
 09:17: Well, momentum space expands accordingly, with the corresponding enormous velocities all inward pointing.
 09:29: But what happens to these as the star approaches an infinitesimal point, the Planck scale?
 09:37: From the point of view of an outside observer so, us this never happens.
 11:50: And you can only push when the rocket is pointing in the right direction.
 12:57: A lot of people point out that OnePunch Man could easily destroy a killer asteroid.


20151125: 100 Years of Relativity + Challenge Winners!
 03:24: ... as we'd get using calculus to determine the acceleration at every point based on the changing ...
 06:21: ... however, that you have to have thrusters pointing in at least two directions on either side of the asteroid to cancel the ...


20151118: 5 Ways to Stop a Killer Asteroid
 06:49: At this point, we can't deflect a large impactor.
 06:58: But at this point, tracking isn't even that helpful.
 08:41: And you guys had some extremely interesting points.
 09:30: 794651519, and a number of others, point out that maybe our definition of life is too restrictive.


20151105: Why Haven't We Found Alien Life?
 11:31: ... point of this philosophy is that the alien hypothesis is a bad place to start ...


20151028: Is The Alcubierre Warp Drive Possible?
 02:03: ... a black hole is predicted by solving Einstein's field equations around a point of extreme positive energy ...
 07:04: The good news is we're going to need a ton of physicists to get to that point.
 09:11: It's dimmed by a crazy 20% at some points.
 09:33: Radio telescopes are now pointed at it.


20151022: Have Gravitational Waves Been Discovered?!?
 02:34: It's worth pointing out that this speed limit is really the speed of causality the speed at which spacetime talks to itself.


20151015: 5 REAL Possibilities for Interstellar Travel
 01:38: No point in launching a slow ship in 20 years if the ship we launch in 50 years overtakes it.
 11:24: ... that point, it perhaps becomes more interesting to ask why other fundamental ...
 12:32: ... in the meantime, in pointing out the indirect detection of gravitational waves, Garreth Dean delivers ...


20151007: The Speed of Light is NOT About Light
 11:39: ... in its expansion, which it won't then you'd get back to your starting point a long, long, long time ...


20150930: What Happens At The Edge Of The Universe?
 02:10: In cosmology, this sort of instantaneous distance is basically what we call the proper distance between two points.
 02:21: The shortest path in spacetime is defined by the geodesic, the path of light between two points.
 02:55: ... event horizon of a black hole is that point beyond which we can never receive information because light from that ...
 08:30: Now, this is a great point.


20150923: Does Dark Matter BREAK Physics?
 08:53: Agen0000, and others, pointed out that Hawking radiation will eventually cause a black hole to evaporate.


20150827: Watch THIS! (New Host + Challenge Winners)
 00:30: Now there's another force that comes up in elementary physics that's also proportional to the distance of a particle from an equilibrium point.


20150819: Do Events Inside Black Holes Happen?
 02:11: At a certain point, I see him in suspended animation, not rotating, not progressing, just frozen.
 07:54: Remember, from our point of view, there are no photons inside.
 07:57: A laser pointer carried by the monkey never enters the black hole, as far as we're concerned.
 09:13: ... the stuff that goes into the black hole collapses to an infinitely dense point called the singularity at the center, ...


20150812: Challenge: Which Particle Wins This Race?
 01:37: At the same time that the orbiting particle passes this point, let's release the second particle from rest from exactly the same height.
 01:47: Now each of them will eventually arrive at the antipodal point on the planet.
 03:12: The point is to figure out the general answer through a combination of physical reasoning and algebra.


20150805: 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: ... the oceans out like taffy, ergo why the oceans bulge out at opposite points along the Earth/Moon ...
 01:00: ... really is a gravity differential from the Moon at points A and B. And at least in this simplified model, there would be two tidal ...
 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.
 07:14: Now, everything that I've just said is oversimplified, but I think it gets the main point across.
 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 ...
 13:22: ... and ask, relative to that clock, are the coordinate positions of two points on Earth's surface ...
 13:31: So in that sense, those two points are not accelerating.
 13:46: For points on Earth's surface, that's not true.
 14:13: ... idea of using a single frame at Earth's center and saying that those two points are not accelerating is that that frame at Earth's center that you're ...


20150729: General Relativity & Curved Spacetime Explained!
 03:32: ... that the falling apple is accelerating, he's pushing his frames past the point of reliability, just like the ant ...
 04:41: In contrast, the world line of a point on Earth's surface is not a geodesic.


20150722: SPECIAL ANNOUNCEMENT + Flat Spacetime Geometry Comments
 02:03: But as John Buluba and [INAUDIBLE] pointed out, after you view it a second time, it starts to make more sense.
 04:32: ... the space time diagrams that I drew in the last episode were from the point of view of inertial observers Blue Gabe, Red Gabe, the ...
 05:06: That accelerating car, at any given moment, from its point of view, is always stationary instantaneously relative to one of those inertial observers.
 05:27: ... it might be the case that by stitching together all of those points of view, the accelerating car might be able to develop a selfconsistent ...


20150715: Can You Trust Your Eyes in Spacetime?
 02:21: Now recall from our earlier flat spacetime episode that points on this blackboard are not locations in a twodimensional physical space.
 02:51: And at that same moment, I shoot a photon from a laser pointer to the right.
 04:10: It points slightly backward.
 04:18: ... be world lines because to be present at two events represented by points on such a line an observer or a photon would have to be moving faster ...
 04:58: These highlighted points in my diagram and in the red guy's diagram correspond to the same events.
 05:02: So those are the same points.
 05:19: ... spacetime diagrams preserve the spacetime interval between points with its weird minus sign, not the Pythagorean Euclidean notion of ...
 06:53: And that's kind of the whole point of talking about spacetime in the first place.
 08:54: Chew on all that because it's our departure point for talking about curved spacetime in the next episode.


20150708: Curvature Demonstrated + Comments
 00:54: But being tangent to the sphere at this point does not mean that you're tangent to this black curve at this point.
 01:01: If instead I look at a vector that's pointing like this, that is tangent to this curve.
 01:28: OK, here's a point of confusion.
 01:48: ... from an entire plane that lies tangent to the sphere at that same point the plane in which this little vector actually ...
 03:43: In fact, suppose that the ant, at this location, takes a great circle going through that same point that is tangent to this curve at that point.
 05:06: There is one point where I did mention the ambient 3D space, but only intrinsically, to talk about parallel transport in a 3D space.
 05:13: Neopick Windfire pointed out that we did that at minute seven in our parallel transport video.
 05:18: ... that point in the video, the Earth it was shown was supposed to be the physical, ...
 06:01: Take two lines that are at the equator of Earth, and both pointing north.


20150702: Can a Circle Be a Straight Line?
 02:26: Intuitively, we know that curve number one, joining points A and B in the diagram is straight, and curve number two is not.
 02:47: Draw a tiny vector with its tail at point A.
 02:49: You can slide that vector from point A to point B along curve one or along curve two while keeping it parallel to its original direction.
 03:00: OK, now draw a vector at point A, specifically that's tangent to curve one and parallel transport that vector to B along curve one.
 03:07: At every point along the way it remains tangent to curve one.
 03:10: ... it to B along curve two, it does not remain tangent to curve two at all points. ...
 03:45: The vector tangent to curve one at point A remains tangent all along curve one as we parallel transport it to point B.
 04:51: Now note that a geodesic is not always the shortest curve between two points.
 04:56: ... piece of our great circle that points the opposite direction is also straight, even though it's not the ...
 05:15: And in other curved spaces, multiple straight lines can join the same two points.
 05:19: As a result, the notion of distance between two points is ambiguous in a curved space.
 05:48: If the result you get is the same, same vector at point B, then your space is flat, otherwise it's curved.
 06:14: But if those geodesics start converging or diverging at any point, then the space is curved.
 08:33: Jordan Filipovski, MaybeFactor, and Sharfy pointed out that most of Australia doesn't get snow, even in winter.
 08:39: And several others pointed out that some parts of Australia do get snow on Christmas, even though it's summer down there.


20150624: The Calendar, Australia & White Christmas
 01:47: Now, eventually, the cycle of seasons will backtrack a full 360 degrees, returning to its starting point.
 05:36: Or maybe at some point, New Zealand will take over the world and force the issue.
 06:52: He also points out that if we put enough of them around the sun that we could cover viewing angles from most star systems.


20150617: How to Signal Aliens
 00:58: ... radio receivers with the total area equivalent to a large city pointed right at Earth full time, our leakage would be hard to detect, let alone ...
 03:13: You have to keep transmitting for a very long time to increase the odds that someone will see the signal or there's not much point.
 06:20: First off, Blackmark52 and Gary Oak both pointed out that the frames of reference video that we linked to is from University of Toronto and not MIT.
 07:13: Other questions that a lot of you asked were similarly noting these points of the parent tension.
 07:26: ... Agen0000 pointed out that you can distinguish ordinary celebration from real Newtonian ...
 07:34: Now, these are exactly the right things to point out.


20150603: Is Gravity An Illusion?
 00:42: ... substantive here, and today I'm going to clarify what exactly this point of view means, why Einstein came to adopt it, and how it planted the ...
 01:02: That's just some XYZ axes to label points in space and a clock to track time.
 01:25: ... velocity because that distinction is meaningless and simply a matter point of ...
 03:12: ... from the preferred point of view of the inertial frame that's attached to the tracks, you, the ...
 03:36: So in the train car's frame, which is accelerating forward, it's as if there's an additional gravitational field that points backward.
 03:51: ... field with the actual gravitational field of the Earth, which points down, it looks like there's a net gravitational field inside the car ...
 04:04: Destin at "Smarter Every Day" has a pretty famous video of a helium balloon in an accelerating car that happens to illustrate this point really well.
 04:37: You can also think that the car's forward acceleration is mimicking some extra gravity pointing backward.
 04:43: ... gravitational field and it's as though the total gravity inside the car points down and back at around a 30degree ...
 07:11: More to the point, Newton, if you're inside the box, there's no way for you to know that you're not in intergalactic space.
 07:57: Doesn't that point of view seem simpler?
 08:43: Huh, that's a good point.
 11:21: Lutranereis points out that one problem with media reporting might be that the reporters lack adequate science background, and that's a good point.


20150527: Habitable Exoplanets Debunked!
 01:45: Basically the habitable zone is more of a guideline, a starting point to narrow down targets of interest.
 01:50: Those estimates you hear of an average of one habitable planet per star in the Milky Way are really just statements about this starting point.
 09:56: ... Consider This points out that despite what I said in the episode, in the SI system of units, ...


20150520: The Real Meaning of E=mc²
 09:56: jancultis, or "yawn"cultis, points out the NASA is great but inefficient and has lots of room for improvement.


20150513: 9 NASA Technologies Shaping YOUR Future
 03:40: ... support, but also have enough give that it wouldn't apply weird pressure points? ...
 07:31: But Sengo brought up two points I want to mention specifically.
 07:46: ... second, Sengo points out that the vision impairment research could be interpreted as ...
 08:04: ... the point of the episode was to stimulate discussion about how you do cost benefit ...
 08:12: I think a lot of you missed this point.
 08:27: ... pointed out that we should send men and women in order to collect more data on ...
 08:41: But INSADreamFactory put a twist on this by pointing out that an all woman crew might increase mission risk.
 09:06: Talia Enright pointed out that all these arguments could apply to a #OccupyVenus Cloud City mission.


20150506: Should the First Mars Mission Be All Women?
 07:19: Have at it in the comments, and feel free to point out anything that I missed or got wrong.
 08:05: However Scina Bocere pointed out that its design is based on something called an O'Neill Cylinder that you can look up on Wikipedia.
 08:38: ... Peden points out that around three minutes, 47 seconds, where we had the ball sort of ...
 09:33: ... question Thomas Archuleta points out another scene from "Babylon 5" that I remember in which Michael ...
 09:52: ... and that atmospheric pressure dropped with altitude, would there be some point near the center of the rim where the atmosphere got so thin that you'd ...


20150422: Are Space and Time An Illusion?
 02:35: A good starting point for objective reality is universal agreement.
 04:45: Its points correspond to events.
 05:01: They correspond to spacetime intervals, which are geometric relations, a nonEuclidean version of the distances between points.
 05:21: The board, its points and geometric facts, are simply there whether we put axis on that board or not.
 05:31: ... then you are a geometric object in spacetime, a line segment joining the points representing the events of your birth and your ...
 07:05: I'll do my best to answer them at the next causallyconnected point of spacetime.
 07:27: ... second, as Nicholas Garrison pointed out, germs do spread more easily space capsules for a variety of ...


20150415: Could NASA Start the Zombie Apocalypse?
 01:58: ... contracted the zombie virus, which lies dormant until you die at which point [ZOMBIE ...
 05:18: At that point, the total amount of gas that you would have released would have been a nontrivial fraction of your body mass.


20150401: Is the Moon in Majora’s Mask a Black Hole?
 03:09: ... Termina's point of view, then, the moon's tidal force manifests itself as an outward ...
 08:22: Gareth Dean pointed out that the early universe contains not just hydrogen but also helium, and asks whether CMB analysis takes this into account.
 08:45: The CMB was emitted from all points of the universe simultaneously.


20150325: Cosmic Microwave Background Explained
 00:16: So pick a dark spot in the sky and point an analog satellite dish at it.
 00:24: Pick another point and more static.
 04:04: ... one final flash of an infinite number of orange bulbs going off at every point in the universe more or less ...
 06:51: ... to everyone who pointed out that we got the aileron flap directions wrong in the video, noted, ...


20150318: Can A Starfox Barrel Roll Work In Space?
 01:24: In fact, MatPat, over at Game Theorists, correctly pointed out that the technical name of this movie is an aileron roll.
 02:09: ... speaking, that narrow points along the axis of rotation, in the same direction that the thumb of your ...
 03:47: So its angular momentum vector points toward the nose of the ship, which here is the top of your screen.
 04:04: When I flip the flywheel 180 degrees, its individual angular momentum starts pointing toward the rear of the ship, i.e.
 05:01: ... difference is that their flywheels point in a fixed direction and gets spun opposite to the way they want the ...


20150311: What Will Destroy Planet Earth?
 00:50: Let's review some possibilities, starting with one that has probably crossed your mind at some point nukes.
 06:50: Viridis Arborem pointed out that Venus also inspired a martial arts style Venutian Aikido used by the third Doctor from Doctor Who.
 07:00: Katherine Daniel and lots of other people point out that it's not necessarily either/or between Venus and Mars.
 07:10: Zevin X points out that the real problem might be planetism.
 07:18: Quite Likely points out that we don't actually know how bad Martian gravity will be for humans, and we don't.


20150304: Should We Colonize Venus Instead of Mars?
 03:19: ... hotter than hell over 450 degrees Celsius, well above the melting point of ...
 03:57: The point is I think surfacism is a real bias.
 04:07: I mean, if a surface will kill us, there's no point in going there, right?
 06:36: ... I hit enlarge once every second, then there will always be two points on the page that if they're far enough apart to begin with will end ...


20150225: How Do You Measure the Size of the Universe?
 01:26: And then you work out how far away the emission point of that light is right now.
 03:28: Now, here comes another important point, so pay attention.
 04:35: And how long it takes to get back to this point is the current age of the universe.
 05:42: PantsuMann and others point out that it would really low odds to accidentally bump into a "Millennium Falcon" in space.
 05:50: ... real point of Fermi paradox is that colonization on a galactic scale could happen ...


20150218: Is It Irrational to Believe in Aliens?
 02:51: And that is Sagan's point.
 03:29: One prominent no aliens argument begins by pointing out that our galaxy is not just very big, but also very old, about 10 billion years old.
 07:11: The Gentleman Physicist points out that Super Mario World could be a platform accelerating through space with rockets at 70 meters per second squared.
