Search PBS Space Time


2022-12-14: How Can Matter Be BOTH Liquid AND Gas?

  • 19:51: ... spectrum - so a lot more nasty UV light, not to mention x-rays and gamma rays, which may wreak havoc on the ozone ...

2022-11-23: How To See Black Holes By Catching Neutrinos

  • 06:13: When cosmic rays hit molecules in our atmosphere, many different particles can be produced, but the most annoying are muons and neutrinos.
  • 07:26: There’s only about 50 neutrinos more than you would expected from cosmic rays in the atmosphere, but it’s pretty clearly something out there in space.

2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table?

  • 05:01: ... - although we do encounter it in nature because it’s created when cosmic rays hit nitrogen nuclei in the ...

2022-10-12: The REAL Possibility of Mapping Alien Planets!

  • 01:25: ... but away from   them both, you’ll reach this spot where light rays from the exoplanet are bent inwards by the Sun’s   gravitational ...
  • 18:29: ... there. Also some transient phenomena - like supernovae, or cosmic ray ...

2022-09-14: Could the Higgs Boson Lead Us to Dark Matter?

  • 03:14: So dark matter detectors consist of huge tubs of liquid or massive chunks of crystal, placed deep underground to avoid cosmic rays.
  • 04:06: ... matter particles somewhere in space could annihilate to produce gamma ray photons, which could be picked up by telescopes like the Alpha Magnetic ...
  • 04:26: ... it’s very difficult to disentangle this source of gamma rays from other astrophysical sources like pulsars, supernovae, and things ...

2022-06-22: Is Interstellar Travel Impossible?

  • 03:50: And that’s to say nothing of cosmic rays - particles moving fast enough to kill all on their own.
  • 12:17: But none of this helps against the other type of radiation - cosmic rays.
  • 12:35: ... radiation dose from cosmic rays is lower than that of the interstellar gas - it’s not instantly lethal, ...
  • 12:48: However it’s harder to protect against cosmic rays because they hit the ship from all directions.
  • 12:55: If you manage to accelerate to 80 or 90% light speed then most of the cosmic rays will hit from in front, and then your windshield protects you.
  • 13:32: ... shielding against the interstellar medium, micrometeoroids and cosmic rays will have to get more ...

2022-02-23: Are Cosmic Strings Cracks in the Universe?

  • 10:09: ... us and a distant light source, it bends all   passing rays of light inwards, so focusing them  towards us. We can see multiple ...

2021-10-05: Why Magnetic Monopoles SHOULD Exist

  • 13:24: ... look for magnetic monopoles coming from space - typically using cosmic ray observatories - or contributing to the Earth’s magnetic field - and in a ...

2021-09-21: How Electron Spin Makes Matter Possible

  • 15:48: ... be able to see the dark disk in the middle. That’s because the light rays will travel a straight line after the slingshot, so at most they can ...

2021-09-07: First Detection of Light from Behind a Black Hole

  • 13:16: Some people have proposed that this is what gamma ray bursts might be.

2021-08-18: How Vacuum Decay Would Destroy The Universe

  • 10:54: ... all, Earth is constantly being bombarded by cosmic   rays of much, much higher energy than the LHC can produce, and no ...

2021-08-10: How to Communicate Across the Quantum Multiverse

  • 16:27: ... to even higher energies. This is believed to be one source of cosmic rays that reach the earth. The magnetic fields then go on to add to the ...

2021-07-21: How Magnetism Shapes The Universe

  • 11:08: Electrons and atomic nuclei can be accelerated in this magnetic field to high energies - into what we call cosmic rays.
  • 11:20: But the most energetic cosmic rays are accelerated by the strongest magnetic fields.
  • 11:47: Those fields grab particles of matter and accelerate them to incredible energies, flinging cosmic rays out into the universe.

2021-03-09: How Does Gravity Affect Light?

  • 05:48: And the equivalence principle tells us we must see the same bending of the light ray in our stationary rocketship set in our gravitational field.
  • 06:10: Can this gravitational time dilation also explain the bending of a ray light traveling horizontally?
  • 06:57: ... if we imagine light as a perfectly narrow ray, or even as a massless, timeless particle, none of our intuitive ...
  • 11:43: ... in the apparent positions of stars around the sun, due to their light rays being “refracted” in the Sun’s gravitational ...

2021-02-24: Does Time Cause Gravity?

  • 07:56: In fact, the imaginary paths of light rays were one the most important tools that helped Einstein develop both special and general relativity.

2020-12-08: Why Do You Remember The Past But Not The Future?

  • 02:55: ... in the chips and dents on its surface, it recalls being hit by cosmic rays in the melt-tracks through its embedded glassy grains, and those grains ...
  • 03:52: Well, more collisions building it up or breaking it down, more cosmic ray hits, that sort of thing.
  • 06:13: Over time the rock changes - new clumps might hit the rock and become embedded, cosmic rays leave their mark, etc.
  • 06:34: ... with all of its detailed structure mysteriously in place - cosmic ray tracks, embedded clumps, bumps and scratches, ...
  • 06:45: ... those features get erased one by one - cosmic rays happen to pass through in exactly the right way to erase their tracks, ...
  • 08:02: Let’s say it’s a final cosmic ray strike.
  • 08:06: ... future, because there’s no way you could predict that future cosmic ray strike with the internal structure of the asteroid ...
  • 08:18: Before the cosmic ray strikes, the asteroid has no knowledge of the incoming impact.
  • 08:22: We would say that the rock and the cosmic ray are not correlated in any way.
  • 08:30: Even without access to the cosmic ray, the rock now holds information about the ray, and the ray holds information about the rock.
  • 08:48: It has this inexplicable scar running through it that is now perfectly removed by a passingly cosmic ray.
  • 08:56: That means that before the cosmic ray hit, the asteroid was correlated with its environment.

2020-11-04: Electroweak Theory and the Origin of the Fundamental Forces

  • 14:41: Dr Kres von Panzer asks how we know that two light rays inside a black hole converge and don’t just perpetually pass each other.
  • 14:51: ... showed that at least some light rays - null geodesics - that start parallel from any trapped surface must ...

2020-10-27: How The Penrose Singularity Theorem Predicts The End of Space Time

  • 05:01: ... free fall in a gravitational field.   The path traveled by a ray of light is  called a null geodesic. They are the   ...
  • 06:38: ... other and   come to a focus. And he also showed that, for rays departing a trapped surface,   it’s meaningless to continue to ...
  • 07:05: ... impossible contradictions arise otherwise. Imagine a pair of light rays emerging from the same point   and then focused back towards ...
  • 12:11: ... insights, and all from   some bright ideas about how light rays travel and terminate at the singular dead ends of ...

2020-10-05: Venus May Have Life!

  • 07:00: You might get some produced by lightning strikes in the cloud layers, or by cosmic rays hitting the upper atmosphere.

2020-08-24: Can Future Colliders Break the Standard Model?

  • 07:41: ... these ultra-high energy cosmic rays are rare, and to reliably detect a new particle we need to watch the ...

2020-08-17: How Stars Destroy Each Other

  • 07:09: ... start, you need to know that when you look at our galaxy in gamma rays - the highest energy light there is - the brightest points you see are ...
  • 07:28: And there are a handful of mysteriously pulse-free gamma ray sources that otherwise look like they should be pulsars.
  • 08:35: The same gas blocks any radio light, but allows the more penetrating gamma ray light to pass through.

2020-07-28: What is a Theory of Everything: Livestream

  • 00:00: ... so this is you know looking for uh you know looking for like cosmic ray cosmic rays gamma gamma ray bursts you know uh uh but also ...

2020-07-20: The Boundary Between Black Holes & Neutron Stars

  • 08:26: We also see the results of these mergers in gamma ray bursts - frequent flashes of energetic light from the distant universe.

2020-07-08: Does Antimatter Explain Why There's Something Rather Than Nothing?

  • 05:43: ... nature - for example in the Sun, or in radioactive decay, or when cosmic rays hit the atmosphere, which is how antimatter was discovered in the first ...

2020-06-15: What Happens After the Universe Ends?

  • 02:59: ... both contain the same number of light rays, which begin traveling in the same direction, although obviously they’re ...
  • 03:08: ... the life of both universes, those rays trace out the same pattern - all the angles between them stay the same, ...

2020-06-08: Can Viruses Travel Between Planets?

  • 09:21: ... virus has survived being bathed in the equivalent of 250 years of cosmic rays, simulated by an intense shower of energetic ...
  • 09:55: Some viruses do have the remarkable ability to sort of reassemble their genetic code after irradiation by UV or cosmic rays.
  • 10:52: ... barrier of rock or ice will shield against ultraviolet light and cosmic rays. ...

2020-04-22: Will Wormholes Allow Fast Interstellar Travel?

  • 14:15: ... you there. Okay so last week we talked about these bizarre giant, gamma ray structures, that seem to have erupted from near the Milky Way central ...
  • 15:35: ... a galaxy, the space between the stars is full of gas, radiation, cosmic rays, and dust. When I say "full", I mean it's everywhere - but its very ...

2020-04-14: Was the Milky Way a Quasar?

  • 02:33: ... each other, the result could be a fireworks show of high-energy gamma rays. ...
  • 03:06: Gamma rays produced by dark matter annihilations should have similar structure.
  • 03:18: ... of a diffuse cloud of gamma rays, they saw a massive pair of high-energy gamma ray bubbles with sharp ...
  • 03:47: Well, it turns out that the plane of the Galaxy also glows brightly in gamma rays.
  • 03:52: This is mostly from cosmic ray interactions with the interstellar medium.
  • 04:06: These “cosmic rays” can then collide with nuclei in the gas between the stars - again, mostly the protons of hydrogen.
  • 04:22: The neutral pion will then decay into a pair of gamma rays.
  • 04:26: And that’s the glow you see when you look at the disk of the Milky Way - if you have gamma ray vision.
  • 04:31: This gamma ray fog was masking the mysterious bubbles lurking in the background.
  • 04:41: The key to finding the Fermi Bubbles was that its gamma rays are even more energetic than the diffuse emission.
  • 04:49: The gamma rays produced by neutral pion decay from these cosmic ray collisions tend to drop off in intensity towards higher energies.
  • 04:57: So, fewer very high energy gamma rays.
  • 05:00: On the other hand, the Fermi Bubbles produce a lot more gamma rays at higher energies.
  • 05:05: The difference in energy distributions - or in their gamma ray spectra, means that the diffuse gamma ray background can be cleanly subtracted.
  • 05:18: In the Fermi Bubbles, gamma rays are generated by a high-energy process known as Inverse Compton Scattering.
  • 05:29: Extremely energetic electrons interact with lower-energy light, boosting that light to the much more energetic gamma ray regime.
  • 12:09: ... we probably don’t need to agonize over any extra gamma rays being generated by this process, because our Earth’s atmosphere absorbs ...

2020-04-07: How We Know The Earth Is Ancient

  • 08:25: ... exists on the surface of the earth because it’s produced when cosmic rays hit nitrogen in the atmosphere, resulting in a constant proportion of ...

2020-03-31: What’s On The Other Side Of A Black Hole?

  • 05:00: ... relativity uses null geodesics - the paths taken by light rays - to grid spacetime, and we also assume that those lines don’t just end. ...
  • 05:49: ... this Penrose diagram is geodesically incomplete because there are light rays with undefined origins. This is equivalent to saying that we have not ...
  • 06:15: ... we trace our light ray backwards from our universe we encounter a region that looks just like ...
  • 10:35: ... hole in their past. And within those black holes, any outgoing light ray can be traced back to the surface of the collapsing star and to its ...

2020-03-24: How Black Holes Spin Space Time

  • 11:31: ... holes are also a contender for another astrophysical phenomenon - gamma ray bursts. When a truly gigantic star collapses at the end of its life, and ...

2020-02-11: Are Axions Dark Matter?

  • 09:45: ... magnetic pulsars - and quasars may convert some of their own gamma ray output into axions - and that dip in gamma ray output may be measurable. ...

2019-12-02: Is The Universe Finite?

  • 06:02: ... fields that act as lenses, slightly deflecting the path of those rays of CMB ...
  • 08:39: In short - lensing by a cluster of galaxies tends to draw rays of light from different blobs together.

2019-11-04: Why We Might Be Alone in the Universe

  • 10:04: ... may have been lucky in avoiding various cosmic catastrophes like gamma ray ...
  • 13:48: And this was NOT observed in the light from a distant gamma ray burst, which presents a challenge for the theory.

2019-10-15: Loop Quantum Gravity Explained

  • 12:41: ... on the energy of the photon, with, for example, high-energy gamma rays travelling a wee bit slower than low energy radio waves due to the way ...
  • 13:02: This was tested in 2009 by looking for differences in the arrival time of light from a gamma ray burst nearly a billion light years away.

2019-09-16: Could We Terraform Mars?

  • 02:15: And of course Earth’s atmosphere protects us from harmful cosmic rays and the most dangerous ultraviolet radiation from the Sun.

2019-07-15: The Quantum Internet

  • 12:15: ... protactinium isotope that itself decays to emit a very high energy gamma ray, and that gamma radiation can fry bomb electronics and is relatively ...

2019-06-17: How Black Holes Kill Galaxies

  • 14:00: But you might see the result of it's decay a particular spectrum of radiation and cosmic rays.

2019-04-03: The Edge of an Infinite Universe

  • 06:35: This particular conformal compactification is designed to ensure that the path of every ray of light remains at 45 degrees across the map.

2018-12-20: Why String Theory is Wrong

  • 14:12: There's a hint from cosmic rays, we talked about it earlier.

2018-12-12: Quantum Physics in a Mirror Universe

  • 00:02: ... the weak interaction into nickel by emitting an electron and some gamma ray photons and neutrinos the cobalt-60 nucleus also happens to have an ...

2018-12-06: Did Life on Earth Come from Space?

  • 00:37: ... UV radiation of a star interstellar space is thick with energetic cosmic rays near light speed atomic nuclei as well as x-rays and gamma rays ...

2018-11-21: 'Oumuamua Is Not Aliens

  • 07:13: ... been fused into a crust by millennia of exposure to interstellar cosmic rays. ...

2018-11-14: Supersymmetric Particle Found?

  • 03:52: ... explosions, gamma ray bursts, black hole magnetic fields are all expected to blast high energy ...
  • 04:02: These are cosmic rays.
  • 04:05: The highest energy cosmic rays can have energies around a billion times that of the LHC.
  • 04:11: Unfortunately, for particle physics experiments cosmic rays at these energies are extremely rare.
  • 04:17: So it's not surprising that we haven't seen supersymmetric particles in our cosmic ray observations yet, or have we?
  • 04:37: It's a cosmic ray experiment of a very special sort.
  • 04:40: In fact, it's a cosmic ray detector disguised as a neutrino detector disguised as a radio antenna disguised as a hot air balloon.
  • 04:50: When ultra high energy cosmic rays travel through space, they bump into the photons of the cosmic microwave background.
  • 05:01: Those cosmic rays lose energy to the CMB, which is partly why the most energetic cosmic rays are so rare here on earth.
  • 05:09: But in those interactions, cosmic rays can create extremely high energy neutrinos.
  • 05:20: So detecting the highest energy neutrinos allows us to learn about the cosmic rays that produced them.
  • 06:08: ... the very highest energy neutrinos, the ones that are produced by cosmic ray interactions with the ...
  • 06:55: That allows it to sort out neutrino radio flashes from the flashes produced by other cosmic rays coming in from above.
  • 10:33: The other event wasn't associated with any supernova or gamma ray burst.

2018-10-25: Will We Ever Find Alien Life?

  • 08:46: ... this likelihood by assuming that a lot of life gets wiped out by gamma ray bursts, a type of cataclysmically exploding ...
  • 09:12: But remember, it's only for the planets not wiped clean by gamma ray burst.
  • 09:17: ... it's gamma ray bursts or something else, our failure to find aliens tells us there must ...

2018-10-10: Computing a Universe Simulation

  • 13:22: Gamma rays should be barely slowed down at all, far less than the measured two-ish seconds time delay.

2018-10-03: How to Detect Extra Dimensions

  • 01:29: The resulting kilonova is first observed in gravitational waves and then as a gamma ray burst.
  • 02:52: We can think of light rays spreading up evenly over an expanding spherical shell.
  • 02:58: If we see that pulse, it means our eye or our telescope intercepts some of those light rays.
  • 03:03: The brightness of the pulse is determined by how many rays we intercept.
  • 03:08: So as this shell expands, the light rays become more spread out.

2018-09-20: Quantum Gravity and the Hardest Problem in Physics

  • 05:38: That's why we use electron microscopes or X-rays or even gamma rays to take images of extremely small things.

2018-08-30: Is There Life on Mars?

  • 05:16: ... inspiring works of fiction like HG Wells, "The War of the Worlds," or Ray Bradbury's "The Martian Chronicles." It turns out that Lowell's canals ...

2018-08-23: How Will the Universe End?

  • 06:18: But there are several beyond the standard-model mechanisms that would allow them to decay into positrons, neutrinos, and gamma ray photons.
  • 08:55: Occasional flashes of gamma rays will light up the darkness as black holes reach that last explosive stage of their evaporation.

2018-04-18: Using Stars to See Gravitational Waves

  • 02:49: First, as a gamma ray burst.

2018-04-04: The Unruh Effect

  • 02:26: ... light ray world lines backwards from our observer defines what we call the past ...

2018-01-10: What Do Stars Sound Like?

  • 10:47: So before the break, we did an episode on what would happen to the earth if we were hit by a gamma ray burst beam.
  • 10:56: Dimitry Ilyin gave a shout out to the excellent Kurzgesagt episode on the gamma ray burst apocalypse.
  • 11:37: Dmitry also asks whether being in a different spot in our orbit can save us from a gamma ray burst.
  • 11:53: ... even if a super-focused 1-degree gamma ray burst hit us from a single light year away, that jet would have diverged ...
  • 12:08: Lewinham asks whether building underground cities would help against a gamma ray burst.
  • 12:39: In fact, the magnetic field of a gamma ray burst focuses charged particles-- electrons and the nuclei of the exploding star.

2017-12-20: Extinction by Gamma-Ray Burst

  • 00:11: Among the scariest is that one day, we will almost certainly find ourselves in the path of a gamma-ray burst's death ray.
  • 02:46: ... explosion sprays high-energy light, so ultraviolet, x-rays, gamma rays, and near-light-speed particles-- so cosmic rays-- into the surrounding ...
  • 03:25: The observed faint flash of gamma rays from exploding stars can last anywhere from a couple of seconds to a few minutes.
  • 03:50: Essentially, all of the gamma rays and x-rays are going to be blocked by our atmosphere.
  • 04:05: ... rays break apart nitrogen and oxygen molecules in the atmosphere, which then ...

2017-09-20: The Future of Space Telescopes

  • 01:44: Train a distant telescope on us, and it would be overwhelmed by the sun's rays.

2017-09-13: Neutron Stars Collide in New LIGO Signal?

  • 01:27: ... merger, and that the event was accompanied by a bright flash of gamma rays. ...
  • 06:54: These gamma ray bursts are relatively common.
  • 07:09: The observed gamma ray burst, GRB, was of that type.
  • 07:25: A Hubble Space Telescope observation was triggered a few days later to look at the location of this gamma ray burst.
  • 07:47: Someone in the know decided that this gamma ray burst was very likely associated with a gravitational wave.
  • 07:55: That blob is the origin of the gamma ray burst.
  • 11:17: ... 100 million light-years' distance by collecting only a handful of gamma rays and by sensing the faint ripples it made in the very fabric of ...

2017-08-30: White Holes

  • 07:20: The light rays from any crossing reach us infinitely far in the future, even if the black hole plunge began far in the past.
  • 07:30: ... hole has an event horizon that's a barrier to entry, but also light rays within that region must move up on the ...
  • 08:06: One, light rays exiting that past white hole can never reach us.
  • 11:51: But what about light rays entering or leaving our eternal black hole from the opposite side?

2017-07-26: The Secrets of Feynman Diagrams

  • 14:07: ... to nickname the Strategic Defense Initiative not Star Wars, but Ronald Ray-gun. ...

2017-07-19: The Real Star Wars

  • 10:08: ... blinded some US spy satellites, and particle beams, actual death rays, which never really ...

2017-06-21: Anti-Matter and Quantum Relativity

  • 09:19: Only a few years after Dirac wrote down his equation in 1928, the positron, the anti-matter electron, was spotted in cosmic rays by Carl Anderson.

2017-05-17: Martian Evolution

  • 07:15: Even more dangerous than the UV are high-energy cosmic rays and solar particles.

2017-04-19: The Oh My God Particle

  • 00:00: ... Long before the God particle, there is the Oh-My-God particle, a cosmic ray vastly more energetic than had ever been seen or was even thought ...
  • 00:13: These ultra-high energy cosmic rays still perplex scientists.
  • 00:17: Where are these extra galactic death rays coming from?
  • 00:51: ... experiment by the University of Utah to spot the highest energy cosmic rays in the ...
  • 01:03: ... analyzing the Fly's Eye data calculated that the cosmic ray responsible for this particular flash must have had a kinetic energy of ...
  • 01:35: In fact, cosmic rays of that energy was supposed to be impossible.
  • 01:40: Let's talk about cosmic rays for a second.
  • 01:48: High energy particles, electrons, and small atomic nuclei, as well as gamma rays, are ejected when heavier radioactive elements decay.
  • 02:42: Cosmic rays had been discovered.
  • 02:44: ... Oh-My-God particle, we've come a long way in the art of catching cosmic rays. ...
  • 03:03: For lower energy cosmic rays, one approach is to look for their Cherenkov radiation.
  • 03:09: All cosmic rays are traveling at pretty close to the speed of light, but that's the speed of light in a vacuum.
  • 03:18: So when cosmic rays enter the atmosphere, they're actually traveling faster than the new, lower speed of light.
  • 03:24: This results in a burst of gamma rays, Cherenkov radiation, that is actually detectable from the ground.
  • 03:31: Higher energy cosmic rays tend to obliterate themselves several kilometers above the ground in massive collisions with nuclei of air molecules.
  • 04:02: ... the collision that produced them and the nature of the original cosmic ray can be ...
  • 04:12: Several facilities around the world are devoted to catching cosmic rays.
  • 04:16: For example, the Pierre Auger Observatory in Argentina monitors a region around 3,000 square kilometers for high-energy cosmic rays.
  • 05:01: By now, we have a pretty good census of the types of cosmic rays that tend to hit the Earth.
  • 05:13: But about 1% of cosmic rays are heavier nuclei, as heavier as iron.
  • 05:16: We also see gamma rays and even anti-matter particles.
  • 05:54: To accelerate a particle to the energies of cosmic rays, you need a particle accelerator.
  • 06:10: For lower energy cosmic rays, it's believed that many, and perhaps most, come from supernova explosions within our galaxy.
  • 06:29: The higher the energy of the cosmic ray, though, the more likely it is to have originated from outside our galaxy.
  • 06:36: The exact sources of these so-called extra galactic cosmic rays are more mysterious.
  • 06:41: But they may come from magnetic acceleration in quasars, or perhaps they're blasted out in gamma ray bursts.
  • 06:47: The most ridiculous cosmic rays, like the Oh-My-God particle, shouldn't exist at all.
  • 07:11: ... rays with energies over 5 times 10 to the power of 19 electron volts, about 8 ...
  • 07:27: For years, it was thought that no cosmic ray could exceed it, except that the OMG particle was six times more energetic.
  • 07:36: Only a very small number of these extreme energy cosmic rays have been seen since the OMG particle.
  • 07:59: But at that distance, sources like quasars and gamma ray bursts should be very obvious.
  • 08:15: It's still a mystery exactly what produces these extreme cosmic rays and how close to us the sources are.
  • 08:22: For cosmic ray astrophysicists, there's a giant invisible particle accelerating elephant in the room.
  • 08:29: Part of the challenge in understanding cosmic rays is that our atmosphere and magnetic field shield the surface of the earth so well.
  • 08:39: ... flashes of light, which may be due to Cherenkov radiation from cosmic rays passing through their eye's vitreous humor, or from the particles ...
  • 09:00: Along with solar outbursts, cosmic rays are one of the most serious obstacles to manned interplanetary travel.
  • 09:07: ... we figure out the origins of these particles, cosmic ray astronomy is becoming an increasingly powerful tool for investigating ...
  • 09:20: ... highest energy cosmic rays, like the Oh-My-God particle, generate collisions far more energetic than ...
  • 09:30: Studying cosmic rays may crack open the mysteries of both the largest and the smallest scales of space time.

2017-03-29: How Time Becomes Space Inside a Black Hole

  • 06:04: Send out a burst of future defining light rays, and they won't spread out evenly because they bend towards the gravitational field.
  • 06:12: As you approach the event horizon of a black hole, more and more light rays are turned towards the event horizon.
  • 07:49: At the moment of crossing, light rays from the event horizon itself are suddenly visible.
  • 08:39: Also in our past light cone are light rays that are pointed inwards, some of them coming from the outside universe.

2017-02-15: Telescopes of Tomorrow

  • 09:06: ... also catch the visible light counterparts to gamma ray bursts, the most energetic explosions in the universe or record the ...

2017-01-25: Why Quasars are so Awesome

  • 07:59: These forming galaxies were continuously blasted with energetic radiation and cosmic rays.

2017-01-19: The Phantom Singularity

  • 10:13: ... the fact that even an outgoing light ray takes infinite time to move any distance, so using boring old time and ...

2017-01-11: The EM Drive: Fact or Fantasy?

  • 12:36: Mr. Rich suggests that lasers and even grasers, gamma ray lasers, are much more efficient for targeted long-distance communication.

2016-12-08: What Happens at the Event Horizon?

  • 03:16: ... mass of the black hole stretches space and time so that light rays appear to crawl out of the vicinity of the event horizon before escaping ...
  • 05:24: ... a light ray starting from really, really far away and coming towards us hugs the ...
  • 07:14: ... it approaches the black hole, these light rays have further and further to travel through increasingly curved ...

2016-10-19: The First Humans on Mars

  • 03:20: ... to protect against high-energy cosmic rays and solar outbursts and from the micrometeorites that also pass easily ...

2016-10-12: Black Holes from the Dawn of Time

  • 05:27: In stars in our galaxy, in distant quasars, even in gamma ray bursts.
  • 07:43: It's possible that certain types of very short gamma ray bursts are these final flashes from PBHs evaporating in our galaxy.

2016-08-10: How the Quantum Eraser Rewrites the Past

  • 11:59: Tsjoencinema would like to know what would exactly happen if a gamma ray burst hit the earth.
  • 12:05: By happy coincidence, the wonderful channel, Kurzgesagt, recently published a whole episode on gamma ray bursts.
  • 13:49: Caleb Tandberg wants to build underwater cities instead of underground cities to protect against gamma ray bursts.
  • 13:58: You don't even need much water at all to fully protect us from the gamma ray burst or the subsequent UV.

2016-08-03: Can We Survive the Destruction of the Earth? ft. Neal Stephenson

  • 05:01: We'd have to have some places that were deeply shielded from radiation in case it was, say, a gamma ray burst.
  • 08:55: But what about gamma ray bursts?
  • 09:34: There's currently at least one star within the danger zone that could produce a gamma ray burst.
  • 09:44: No planetary surface or space ark in the solar system would be safe from a supernova or a gamma ray burst.
  • 09:54: ... them occupied permanently, because we may not know when the next gamma ray burst is ...
  • 10:09: ... range of a supernova and beyond the width of a typical gamma ray burst death ...

2016-06-22: Planck's Constant and The Origin of Quantum Mechanics

  • 05:00: ... the beginning of the 20th century, a couple more Brits, Lord Rayleigh and Sir James Jeans, attacked the problem with a relatively new idea ...
  • 05:36: The resulting Rayleigh-Jeans law described the blackbody spectrum perfectly.
  • 06:11: It was catastrophic because it meant that something was fundamentally wrong with the classical physics that went into the Rayleigh-Jeans law.
  • 06:28: The Rayleigh-Jeans calculation allows particles to vibrate with any amount of energy, all the way down to infinitesimally tiny wiggles.
  • 06:51: ... Rayleigh and Jeans were chasing Zeno's tortoise, infinitely dividing the smallest ...

2016-06-15: The Strange Universe of Gravitational Lensing

  • 01:50: The prediction of general relativity that gravity deflects the path of light rays was one of the first to be directly verified.
  • 02:57: The gravitational field of any massive object converges passing light rays, like a badly designed lens.

2016-06-08: New Fundamental Particle Discovered?? + Challenge Winners!

  • 01:42: And some are so hopelessly unstable that they decay into high energy light-- gamma rays-- before they ever reach a detector.
  • 02:00: ... Higgs boson was found because there was a slight excess in gamma ray flashes at 125 gigaelectron volts above the otherwise smooth spectrum of ...
  • 02:24: When it was first spotted, this gamma ray excess was just a little bump.

2016-05-04: Will Starshot's Insterstellar Journey Succeed?

  • 06:23: Everything will have to withstand tens of thousands of G's of acceleration and impact from interstellar dust or cosmic rays.

2016-04-06: We Are Star Stuff

  • 09:45: ... some also bursts out as gamma rays, as gravitational radiation, but also as a blast of newly formed heavy ...

2016-02-03: Will Mars or Venus Kill You First?

  • 04:29: See, space is flooded with extremely energetic solar radiation and cosmic rays.

2015-06-17: How to Signal Aliens

  • 02:31: ... flashes to know that you don't have a false positive from a cosmic ray or ...

2015-03-04: Should We Colonize Venus Instead of Mars?

  • 00:33: Two Ray Bradbury stories, a plant that eats flies, and a razor?
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