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

  • 00:08: Black holes are probably the most bizarre of astrophysical objects.
  • 11:25: ... stand to learn a ton about the regions around these gigantic black holes, and eventually from the many other energetic environments that probably ...
  • 11:35: Supernovae, colliding neutron stars and black holes, tidal disruption events when black holes rip apart stars, you name it.

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

  • 01:25: ... than New York City.   You might recall these pictures of the black holes in the M31 galaxy and the center of the Milky Way.   These were ...
  • 12:52: ... exoplanets.  And, actually, for distant galaxies and   black holes and literally anything else for  which we want extreme resolution ...

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

  • 04:26: ... sources like pulsars, supernovae, and things being eaten by black holes. ...

2022-06-22: Is Interstellar Travel Impossible?

  • 12:29: These things are accelerated in the monstrous magnetic fields of black holes and supernovae and of the galaxy itself.
  • 15:16: ... involving a pretty crazily abstract idea including imaginary replica black holes connected by virtual ...
  • 18:03: And we even have ideas for black holes in theories of quantum gravity - for example, the fuzzball of string theory, which we did an episode on.
  • 18:26: Could this, for example, show us how black holes deviate from theory?

2022-06-15: Can Wormholes Solve The Black Hole Information Paradox?

  • 00:00: ... Black holes are very real, but  are also a theoretical nightmare.   ...
  • 00:26: ... picture in which each black hole behaves like many parallel black holes connected by ...
  • 01:40: ... from me, should be enough.   Stephen Hawking discovered that black holes aren’t quite as, well, black and inescapable   as we thought. They ...
  • 02:24: ... - information not observable in the system’s gross properties. Black holes   have huge entropy because every black hole  looks the same no ...
  • 04:21: ... black hole loses its internal storage   space. Meanwhile the black hole’s entropy   decreases. Actually, the black hole ...
  • 04:44: ... should contain no information about anything   besides the black holes gross properties.  Efforts to resolve the black hole ...
  • 08:36: ... to consider   a lot of different geometries - after all,  black holes are pretty simple objects - it’s   not like there are many ...
  • 10:06: ... black   holes rather than just one. The entropy of  many black holes is an example of a quantity   called the Rényi entropy. You ...
  • 10:42: ... integral. For a spacetime geometry where none   of the black holes interact with each other, the entropy doesn’t change from Hawkings’ ...

2022-06-01: What If Physics IS NOT Describing Reality?

  • 13:41: ... van Oosterhout asks what happens to  the central black holes of galaxies that the   milky way eats. The answer is simple - ...

2022-04-20: Does the Universe Create Itself?

  • 16:56: ... be a black hole because the difference between the masses of our largest black holes in the our universe and the whole universe is much too ...
  • 17:08: ... a black or a white hole then it formed by a different process than the black holes that we’ve observed in our universe. The gap between the masses is too ...
  • 17:39: ... universe - adding together all the stars, dark matter, other black holes, etc - then it’s event horizon is the same size as our ...

2022-03-30: Could The Universe Be Inside A Black Hole?

  • 00:25: But we know it must: at the centers of black holes and at the Big Bang.
  • 00:36: Well it turns out that black holes and the Big Bang have more in common than vexing Einstein.
  • 00:56: First up, black holes.
  • 05:19: ... being, their residence in the future versus the past. And the fact that black holes are embedded within a greater universe While the big bang is the entire ...
  • 09:30: And that’s true even after the black hole’s event horizon forms.
  • 10:27: ... that case, black holes don’t form singularities, but rather bounce back outward to create a new ...
  • 11:08: ... from within, and Hawking’s argument that equates white holes with black holes, then there’s a roundabout way to argue we might not NOT be in a black ...
  • 11:52: However if we are in a black hole then there’s a huge upside: we now know what the interior of a black holes look like. It looks like this.
  • 12:16: ... that they are in a black hole and so on ad infinitum in a series of black holes, forming an infinitely nested space ...

2022-02-16: Is The Wave Function The Building Block of Reality?

  • 14:52: ... BuzzBen asks what happens when gravitational waves pass through black holes. Is there gravitational lensing? Well that’s exactly right. Gravitational ...
  • 16:00: ... R asks how we can know that a black hole’s mass has time to crush down to the singularity, given that time dilation ...
  • 18:15: ... asks a related question, but now it’s for black holes that shrink due to Hawking radiation. This is a lot more speculative. ...
  • 18:37: ... Well thank you dannymac63. But remember, we don’t know whether black holes radiate actual information. It could be that they, and so by your ...

2022-02-10: The Nature of Space and Time AMA

  • 00:03: ... i played which were the most popular questions that were not about black holes and i apologize for missing the many questions that were on black ...

2022-01-27: How Does Gravity Escape A Black Hole?

  • 03:07: Shouldn’t a black hole’s event horizon protect the universe from its own malicious influence?
  • 03:27: There’s no question here - a black hole’s gravity doesn’t care about the event horizon at all.
  • 05:40: This explanation works for the black holes of general relativity.
  • 06:38: But doesn’t that make things worse for black holes?
  • 11:53: To sum up - don’t mess around near black holes hoping that the event horizon will protect you from the black hole’s gravity.

2022-01-19: How To Build The Universe in a Computer

  • 07:57: ... stars, it forms  whirlpools and jets around  new stars and black holes. ...

2022-01-12: How To Simulate The Universe With DFT

  • 14:43: ... we have the one about black holes puncturing the Earth, and then the one about how we might search for ...
  • 14:52: Black holes first.
  • 16:21: And speaking of black holes hitting the Sun, Christian asks whether that would be detectable.

2021-12-29: How to Find ALIEN Dyson Spheres

  • 13:11: In the past couple of years researchers have been thinking about Dyson spheres built around the supermassive black holes in the centers of galaxies.

2021-12-20: What Happens If A Black Hole Hits Earth?

  • 00:00: ... remember when I first learned about black holes I imagined these gigantic cosmic vacuum cleaners that must eventually ...
  • 00:29: ... big black holes are very, very far. The nearest known is - the Cygnus X-1 black hole - ...
  • 01:23: ... in density eventually collapsed into stars and galaxies instead of black holes. ...
  • 01:49: ... of the early universe that saved all of matter from collapsing into black holes. But that doesn’t mean that no black holes were formed. There would have ...
  • 02:10: ... call these primordial black holes, and we’ve talked about them before. We’ve also talked about how these ...
  • 02:27: ... when they formed, PBHs could have virtually any mass - from tiny ‘micro’ black holes all the way up to the supermassive black holes in the centers of ...
  • 02:50: ... example, if there were enough of these black holes then they’d frequently pass in front of more distant stars, magnifying ...
  • 03:00: ... kilograms - or around 15% the mass of our Moon. Meanwhile, if primordial black holes had masses smaller than around a trillion kilograms then they'd have all ...
  • 03:25: ... window of possible masses, comparable to the masses of large asteroids. Black holes this big don’t devour stars like Cygnus X-1, and they don’t warp the ...
  • 04:01: ... in the solar system at any given time. If that dark matter is tiny black holes then we might expect dozens, maybe even thousands, of them to be in the ...
  • 06:02: ... - much hotter than the cores of a star. This is how we “see” black holes like Cygnus X-1 or the supermassive black holes in quasars - from the ...
  • 06:35: ... That same radiation causes an outward pressure that partly counters the black hole’s intense gravity. Try to feed a black hole too fast and it starts to ...
  • 08:16: ... there was only one shockwave detected in the Earth’s atmosphere, and a black hole’s exit on the other side of the planet should have made another. These ...
  • 08:41: ... devastation is only for black holes at the top end of our mass range. The smaller the black hole, the more ...
  • 09:24: ... black hole hitting the earth every million years. For the Phobos-mass black holes or larger, you may only get one in the history of the earth. The fact ...
  • 10:16: ... the earth’s atmosphere nor its surface would keep a good record of micro black holes hitting the earth. Earth’s dynamic interior and its eroding atmosphere ...
  • 10:44: ... apart craters made by black holes and those made by regular old rocks is hard, but not impossible thanks ...
  • 12:24: ... a serious search has not yet been done. OK guys, to wrap up- have any black holes ever hit the earth? We don’t know. We probably wouldn’t have noticed if ...
  • 12:44: ... not be discounted. But the discovery would also tell us that primordial black holes are a thing, and it would tell us about their ...
  • 17:55: ... should look almost exactly the same as those produced when classical black holes merge. Emphasis on the ...
  • 18:16: ... back into a spheroid - lasts longer for fuzzballs than for regular black holes due to the event horizon being less cleanly defined. It’s also been ...
  • 19:14: ... fact that the connection between multi-dimensional cats, hairballs and black holes can’t possibly be wrong. I agree that this is a compelling reason to ...

2021-12-10: 2021 End of Year AMA!

  • 00:02: ... space i like to look at quasars that way quasars being gigantic black holes in the process of consuming material from their surrounding galaxy ...

2021-11-17: Are Black Holes Actually Fuzzballs?

  • 00:02: Black holes are a paradox.
  • 00:20: ... in the black holes of string theory - fuzzballs - are perhaps even weirder than the regular ...
  • 00:50: And we see these black holes - or at least their incontrovertible evidence - in many places out there in the universe.
  • 00:57: But black holes are also impossible.
  • 01:48: Black holes should have an enormous number of so-called microstates - hidden configurations - and this translates to an enormous entropy.
  • 01:58: ... Bekenstein, who, incidentally, also inspired the colourful phrasing that black holes “have no hairs” to describe the absence of observable microstates in a ...
  • 02:52: Not so in the black holes of general relativity.
  • 03:13: Black holes evaporate by emitting Hawking radiation.
  • 03:17: ... Hawking radiation should be completely random, and so leaks away the black hole’s mass without any of the information that went into building the black ...
  • 03:48: So yeah, black holes seem to be paradoxes.
  • 05:32: In string theory, black holes are not hairless at all - in fact all of those strings make them positively fuzzy.
  • 06:01: ... of the black hole singularity, because instead of collapsing all of a black hole’s mass into a single point, it gets distributed around the ring structure ...
  • 07:13: ... to think that string theory might explain where the microstates of black holes ...
  • 07:40: ... State dug into that model to see if it could reproduce properties of black holes beyond the ...
  • 08:00: This was another stunning match to theory, and also a way for stringy black holes to leak out their information.
  • 08:06: ... good, but I realize that I haven’t really told you what these stringy black holes look like, or how they form, or how structure can actually be supported ...
  • 08:22: First, a thing that’s weird about even regular black holes.
  • 08:26: If you were to dial up the strength of gravity, black holes would get bigger.
  • 08:39: This property of black holes is actually quite hard to reproduce in theories of quantum gravity.
  • 08:45: ... while he was exploring stringy black holes, Samir Mathur found that the strings that formed the black hole would ...
  • 09:09: ... this is right, then black holes don’t have an empty event horizon at all, but rather a real surface that ...
  • 10:46: But from a distance, fuzzballs would look like black holes.
  • 11:02: All classical effects of black holes from general relativity would be preserved.
  • 11:54: Instead of the 4 spatial dimensions of a Strominger-Vafa or the 3 dimensions of regular black holes, let’s think about a 1-D black hole.
  • 13:19: Constructing fuzzballs that more closely match real astrophysical black holes remains a major theoretical effort.
  • 13:35: Black holes, or something like them, definitely exist.

2021-11-10: What If Our Understanding of Gravity Is Wrong?

  • 01:02: ... speculative ideas of what it might be made of - from exotic particles to black holes. ...
  • 14:31: For instance, CuriosityStream has Black Holes: Messages from The Edge of Space, which examines not only black holes, but neutrino astronomy.

2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light

  • 15:23: Erik says that if magnetic monopoles are massive enough to collapse the early univeres, wouldn’t we only find them inside black holes?
  • 15:36: ... certainly possible that magnetic monopoles to end up inside black holes, in fact some recent work suggests that an individual magnetic monopole ...
  • 16:01: And presumably if black holes had enormousmagnetic charges we’d see that in the way they interact with matter.
  • 16:08: As it is, the magnetic fields we observe around black holes seem more consistent with regular dipole fields, with both north and south poles.

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

  • 15:34: ... - the one about reverberation mapping, where we map the stuff around black holes by watching how light bounces ...
  • 15:48: ... Gorman says that he imagined that black holes would look more like dim stars rather than, well, black holes because ...
  • 16:27: ... speeds out of the Milky Way. Happily the winning hypothesis of enormous black holes was as awesome as all the others. Dave Lawrence rightly calls me out ...

2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe

  • 00:00: ... to lots of weird places on this show - from the interiors of black holes to   the time before the big bang. But today I want to ...
  • 00:25: ... arguably the strangest objects in the universe - if we don’t count black holes   as actual objects. And honestly, neutron stars are even weirder ...
  • 10:06: ... much weaker than the signals we’ve detected when neutron stars or black holes merge,   and so it’s much harder to detect them. But instead ...

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

  • 00:07: Our cleverest astronomers have figured out ways to catch light that skims the very edge of black holes.
  • 00:36: This is obviously cool stuff - I mean, really anything new with black holes captures the public attention.
  • 00:46: ... years - trying to understand what happens in the vicinity of the largest black holes in the ...
  • 01:21: And the more recent version of this in polarized light shows the grain of the magnetic field right near the black hole’s edge.
  • 03:13: ... by the way, is the actual technical term for the largest black holes in the universe - anything more than a million or so times the mass of ...
  • 06:52: One - it’s pouring in, rivers of gas dragged down by the black hole’s gravity.
  • 10:49: A portion of that light was then grabbed by the black hole’s gravitational field and slung right back around towards us, and magnified in the process.
  • 11:54: ... just love it when we can map the space around black holes by watching flickering points in the sky, and in that flickering ...

2021-08-03: How An Extreme New Star Could Change All Cosmology

  • 09:18: ... that saps away their orbital energy. We’ve seen the result of this with black holes and neutron stars when LIGO detected the gravitational waves from the ...

2021-07-21: How Magnetism Shapes The Universe

  • 00:43: Threads tugged lightly towards the Earth, tightly towards the Sun, or into inescapable knots towards black holes.

2021-06-16: Can Space Be Infinitely Divided?

  • 09:58: ... get virtual spacetime fluctuations, and  even virtual black holes and wormholes - a   fluctuating roil of spacetime that John ...

2021-06-09: Are We Running Out of Space Above Earth?

  • 14:14: Last episode was on Planck Relics, those subatomic scale black holes that could be literally everywhere and even explain dark matter.
  • 14:25: Matt Kelly asks what happens to normal matter when it interacts with one of these tiny black holes.
  • 15:24: But the planck mass defines the mass of a black hole one Planck length in radius, and remember, black holes are massive!
  • 16:05: ... of you hypothesized that there being tiny black holes everywhere perfectly explains one of the most vexing paradoxes in the ...

2021-05-25: What If (Tiny) Black Holes Are Everywhere?

  • 00:00: It’s fair to say that black holes are the scariest objects in the universe.
  • 00:20: Black holes are scary because they’re so… final..
  • 00:31: ... if nothing can emerge from a black hole, then black holes must be A) black - they can’t emit light, and B) eternal - they can only ...
  • 01:01: He showed that black holes must radiate, and so slowly leak away their mass in what we now call Hawking radiation.
  • 01:31: These remnant black holes, or Planck relics, may be everywhere.
  • 01:51: It came from thinking about how black holes interact with the quantum fields from which all elementary particles arise.
  • 03:08: ... such black holes the Hawking radiation is just photons - electromagnetic waves with ...
  • 03:45: ... far distant future in which the stars have gone out and we only have black holes, which one by one vanish in bright pops of Hawking ...
  • 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.
  • 06:31: This would be when the black hole’s mass is around 20 micrograms - what we call the Planck mass.
  • 07:04: ... relics do exist they probably don’t look just like mini versions of big black holes. ...
  • 07:22: The only way to make black holes in the modern universe is in the deaths of massive stars.
  • 07:29: The smallest such black holes will take something like 10^66 years to Hawking-radiate their entire mass away.
  • 07:37: That’s much longer than the current age of the universe, none of these black holes will have become Planck relics.
  • 07:45: For Planck relics to exist now we need a way to make black holes that are much smaller than a star.
  • 07:59: It’s something we discussed before - primordial black holes.
  • 08:03: ... Big Bang, there are a few different ways to produce enormous numbers of black holes, potentially of a wide range of ...
  • 08:12: There are some scenarios that allow extremely large numbers of very tiny black holes.
  • 08:19: ... the most important consequence of having Plank relics from primordial black holes is that these could potentially explain dark ...
  • 08:41: It may have been possible to create this insane abundance of black holes if they formed during the epoch of cosmic inflation.
  • 08:56: Back then, the density fluctuations may have been strong enough to generate crazy numbers of tiny black holes.
  • 09:14: ... did a video on this also, but long story short: if black holes radiate a perfect thermal spectrum then, by definition, that radiation ...
  • 09:41: But what if black holes never fully evaporate?
  • 09:58: A way around this has been proposed - what if space inside black holes actually expands to a region larger than the event horizon?
  • 10:22: This conjures images of insane numbers of minuscule black holes swarming through the universe, and in each one a new inflation - a new universe?

2021-05-19: Breaking The Heisenberg Uncertainty Principle

  • 09:13: ... events - events from further away, and involving lower-mass mergers of black holes and neutron ...

2021-05-11: How To Know If It's Aliens

  • 14:35: ... one about whether dark matter can be explained by enormous numbers of black holes - tldw - it probably ...
  • 16:32: ... Williams asks what the difference between super small black holes or naked singularities and WIMPs be. Normally when people talk about ...
  • 18:02: ... many of you commented that you thought of the idea that dark matter is black holes years ago. That’s impressive - you’re in the company of some very smart ...
  • 18:16: ... matter ain’t black holes. That may have sounded unnecessarily snarky - and it wasn’t meant to be - ...
  • 18:32: ... for dark matter in, say, string theory, before you check whether it’s black holes is like looking for your keys in the freezer before checking your ...

2021-04-21: The NEW Warp Drive Possibilities

  • 03:01: For example inside black holes where we can think of space as flowing downwards faster than light.
  • 11:47: ... remain - can the required energy densities be created without creating black holes for any useful sized warp ...

2021-04-13: What If Dark Matter Is Just Black Holes?

  • 00:00: ... be that for every star in the universe there are billions of microscopic black holes streaming through the solar system, the planet, even our bodies every ...
  • 01:03: What if dark matter is just black holes?
  • 01:13: As we’ve discussed many times before, black holes are regions of gravitational field so intense that not even light can escape.
  • 01:21: Evidence for the reality of black holes is now pretty convincing - and we’ve talked about this evidence before.
  • 01:25: ... fact that we know black holes are actually real seems like a significant point in their favor as an ...
  • 01:53: ... for black holes to be dark matter they’d need to be abundant enough to make up all of ...
  • 02:02: In other words, most of the physical universe needs to be vast swarms of black holes that outweigh all the atoms in the universe by a factor of four.
  • 02:15: The main remaining variable is the mass of the individual black holes.
  • 02:19: We could get to the required dark matter mass with lots of massive black holes, or ludicrously many smaller black holes.
  • 02:37: If a study doesn’t find enough of black holes in that range, then that mass range is ruled out as a main contributor to dark matter.
  • 02:50: Our hypothesis is that dark matter is made of black holes.
  • 02:53: ... we’re going to go through the mass spectrum of black holes, and close one window after another - we’ll see at the end whether there ...
  • 03:06: ... before we start eliminating specific black holes masses, let’s rule out an entire class of black holes. In face we're ...
  • 03:16: We know black holes form from the remaining cores of the most massive stars, after they explode as supernovae.
  • 03:21: ... can make a pretty good estimate of the maximum possible number of these black holes by estimating the number of stars that formed and died through cosmic ...
  • 03:37: ... can also see the products of the supernova explosions- not so much the black holes produced in those explosions, but the heavy elements forged in the cores ...
  • 03:47: ... us there haven’t been anywhere near enough supernovae to give us enough black holes to make up all of dark ...
  • 04:18: So if dark matter is made of black holes then those black holes must have been with us from the beginning.
  • 04:23: Fortunately for our hypothesis, there is a reason to think that colossal numbers of black holes may have formed in the very early universe.
  • 04:32: We call these primordial black holes.
  • 04:35: Now, we’ve talked about them before, but let’s dig much deeper into the question of whether primordial black holes could explain dark matter.
  • 04:44: There are a few ways primordial black holes could form.
  • 05:03: ... strong enough that the most massive of them would have collapsed into black holes. ...
  • 05:13: ... those black holes should have all formed at around the same mass - but that mass depends ...
  • 05:43: The most massive black holes in the universe weigh in at millions to billions of times the mass of our Sun.
  • 05:48: We see these “supermassive black holes” in the centers of essentially all galaxies.
  • 06:00: At the opposite end of the mass spectrum we have the black holes under a billion tons or around the mass of a small mountain.
  • 06:17: We can also rule out black holes a bit larger than this as dark matter.
  • 06:20: ... dark matter to be made of black holes with masses around that of a larger asteroid or small moon, we’d need ...
  • 06:38: ... though these black holes would have microscopic event horizons, at those insane abundances, ...
  • 07:30: Probably no more than a few percent of the dark matter mass can be from these micro black holes.
  • 09:22: And we can’t rule out these as primordial black holes, nor as Reapers - but there’s no good evidence of either.
  • 09:30: So far we’ve mostly ruled out black holes around the Sun’s mass or lower as an explanation for dark matter.
  • 09:37: ... black holes are tricky, because you need fewer of them to make up the mass of dark ...
  • 09:46: ... I mentioned, the most massive black holes trickle to the center of our galaxy, but there’s an intermediate mass ...
  • 10:01: ... galaxies are so small and dense that even black holes with tens of solar masses should have trickled to the center by now, and ...
  • 10:11: ... dwarf galaxies tells us that no more than 4% of the dark matter could be black holes of tens to thousands of solar ...
  • 10:20: ... our galaxy gives us similar constraints - if there were lots of black holes of several tens times the Sun’s mass then these binaries would long ago ...
  • 10:57: ... dark matter probably isn’t black holes - but don’t be sad - that means dark matter is probably something that ...

2021-03-23: Zeno's Paradox & The Quantum Zeno Effect

  • 15:08: But it's different with gravitational waves from merging black holes.
  • 15:21: ... black holes spiral towards each other, the frequency of the last phase of the ...

2021-03-16: The NEW Crisis in Cosmology

  • 11:57: ... long we may even be able to use gravitational waves from merging black holes   to measure the Hubble constant. These waves get stretched by the ...

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

  • 00:38: ... stop, and fall back - and so was the first to predict the existence of black holes. ...

2021-02-17: Gravitational Wave Background Discovered?

  • 00:00: ... built this giant machine that spotted gravitational waves from colliding black holes well we've just taken it to the next level with a galaxy spanning ...

2021-01-26: Is Dark Matter Made of Particles?

  • 01:13: Now it’s possible that dark matter is not particles - it could be black holes or failed stars or even weirder so-called “compact objects”.

2021-01-19: Can We Break the Universe?

  • 00:02: Black holes, gravitational waves, he was even the first to realize that friggin lasers could be a thing.

2020-12-22: Navigating with Quantum Entanglement

  • 14:28: And then those black holes evaporate into radiation on a comparitifly short timescale.

2020-12-15: The Supernova At The End of Time

  • 00:35: ... interesting thing to happen will be the final explosions as the last black holes evaporate - and even those will be relatively weak-sauce as far as space ...
  • 02:06: Much more climactic that the previous version, which had black holes fizzling out - at least this one has some decent ka-booms.
  • 09:20: ... those iron stars are also doomed - they’ll quietly become black holes themselves through countless aeons of more quantum tunneling - something ...

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

  • 00:34: ... Black holes have haunted our  theories of gravity since the 1700s.   ...
  • 01:17: ... in the theory. Einstein himself doubted that  the black holes could form in the real universe,   and even if they could, ...
  • 02:16: ... the intriguing and terrifying possibility  that black holes might really exist   inspired some of our greatest minds  ...
  • 04:35: ... to Einstein’s theory plus a couple of assumptions,   black holes must contain singularities. And this is true regardless of how the ...
  • 05:01: ... condition of general relativity, and it almost certainly holds in black holes. ...
  • 05:55: ... - no big   surprise there. But the crazy thing about  black holes is that null geodesics beneath   the event horizon that are ...
  • 08:49: ... at the   point-like central singularity, while in Kerr  black holes space ends at the ring ...
  • 09:31: ... Roger Penrose’s discovery, black holes and the singularities within had to be taken more   ...
  • 10:36: ... showed that Penrose’s arguments  about black holes also applied to the   universe - that geodesics traced ...
  • 12:11: ... for his contributions to our   theoretical understanding of black holes. He shared it with Andrea Ghez and Reinhard Genzel,   who ...

2020-09-08: The Truth About Beauty in Physics

  • 09:42: ... or a photon bouncing between mirrors - but the resulting theory predicts black holes, gravitational waves, and even the big ...

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

  • 14:28: ... get to your questions Jason Carter asks a tricky one: when two black holes merge and share a single, warped event horizon, shouldn’t there be a ...
  • 14:59: In the case of the merging black holes, you can think of space as more flowing towards the center of mass - although it’s not quite that simple.

2020-08-17: How Stars Destroy Each Other

  • 02:16: ... produced by white dwarfs, to X-ray binaries created by neutron stars and black holes - and much weirder things ...
  • 10:54: ... that seemed to straddle the mass between black holes and neutron stars, and which will change the way we think about ...
  • 12:10: Dead stars aren’t the only way to make black holes.
  • 12:12: ... black holes may have formed from the extremely dense matter of the early universe, ...
  • 12:21: ... fact, people have considered primordial black holes as an explanation for other LIGO mergers - which often involve black ...
  • 12:32: ... it’s also possible that primordial black holes could be less massive than black holes that come from stars, so might ...
  • 12:44: ... primordial black holes exist in some abundance at these masses, then the universe should be ...
  • 12:56: LIGO hasn’t seen that background yet - which actually limits how many such primordial black holes there might be.
  • 13:03: ... this background then it’ll become less and less likely that primordial black holes are responsible for any LIGO ...
  • 13:37: Frank and Jim asked how the event horizons of merging black holes change just before they combine.

2020-08-10: Theory of Everything Controversies: Livestream

  • 00:00: ... in the very early universe towards the big bang or in the center of black holes but also in principle every time we bring a particle into a ...

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

  • 00:00: ... it works it explains gravitate it predicts gravitational waves and black holes all these zany things that have been observed experimentally it takes ...

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

  • 00:10: And we just did - an object on the boundary between neutron stars and black holes, which promises to reveal the secrets of both.
  • 00:29: ... ripples in the fabric of spacetime due to a cataclysmic collision of black holes billions of light years ...
  • 04:18: ... would be the case if both objects were black holes, but even if the smaller object was a neutron star it could well have ...
  • 04:39: To understand that, we have to understand a bit more about black holes and neutron stars.
  • 05:42: ... fact neutron stars are on the verge of being black holes, which by definition have an escape velocity at the event horizon equal ...
  • 09:47: ... to be a gap in masses between the biggest neuron stars and the smallest black holes, but actually we very much expect ...
  • 09:58: New black holes are formed when the most massive stars die and the core is too big to become a neutron star.
  • 10:04: But you don’t get this smooth transition from neutron stars to black holes.
  • 10:24: That increases the black hole’s mass quite a bit.
  • 10:41: ... models of how stars die - or find some other way to make extra-teensie black holes. ...
  • 11:57: I know, it’s small as far as black holes go - but we hope it adequately reflects our thanks.

2020-06-30: Dissolving an Event Horizon

  • 00:28: Strange things happen inside black holes.
  • 02:22: According to the so-called no-hair theorem, black holes can have only three properties - mass, electric charge, and spin.
  • 02:31: Mass is what makes a black hole a black hole, and so the simplest black holes have only this property.
  • 02:37: These are Schwarzschild black holes, and with only mass that means they also only have inward-pulling gravity.
  • 04:20: Reisner-Nordstrom black holes also have an inner horizon, interior to which space and time seem normal-ish.
  • 05:29: Normal black holes leak their mass away by emitting Hawking radiation.
  • 05:33: That radiation cian be any type of elementary particle - but in the case of the most massive black holes, it’s mostly just photons.
  • 05:45: In very massive black holes the Hawking radiation has trouble mustering the energy for anything but weak photons.
  • 06:06: This can’t happen with rotating black holes because they leak away their angular momentum as well as their mass.
  • 06:25: So naked singularities don’t Hawking-radiate, and extremal black holes radiate only very slowly.
  • 06:47: At first glance, it appears that extremal black holes are certainly possible.
  • 07:11: Rotating black holes gain their angular momentum from things they swallow.
  • 08:55: ... any rate, our observations of gravitational waves from colliding black holes and various other methods for estimate black hole spin has not yet ...
  • 09:09: For charged black holes the situation is in some ways easier, but has its own weirdness.
  • 09:17: We don’t actually expect real, astrophysical black holes to retain any significant change.
  • 11:16: ... responses last week, so today we’re covering two episodes - building black holes in the lab with analog event horizons, and Roger Penrose’s conformal ...
  • 11:34: In representations of black holes as funnels, or wormholes as tubes, what does that funnel or tube really represent?

2020-06-22: Building Black Holes in a Lab

  • 00:00: Black holes are very real, but our understanding of them remains highly theoretical. If only we could build one in the lab. Oh wait, we can.
  • 00:16: ... Black holes are about the worst subjects for direct study in the universe. First ...
  • 01:11: ... ourselves of their existence. Actually studying the physics of real black holes is much, much harder. I mean, we could try to make one - but that’s way ...
  • 01:29: ... to at least get started with the lab work. We can instead study analog black holes - and by analog, I don’t mean old fashioned clockwork black holes - I ...
  • 01:54: ... whole idea of analog black holes was started in 1972 by Bill Unruh - most known for his Unruh radiation, ...
  • 04:08: ... and found a number of systems with event horizons Analog theoretical black holes are all very well, but their real value is that they tell us we might be ...
  • 05:25: ... episode, but let’s review. In 1974 Stephen Hawking predicted that real black holes would, contrary to prior thought, leak away their mass as a type of ...
  • 06:33: ... in fact Hawking-like radiation has been observed in these analog black holes. Or at least, the perturbations in the frequencies of the surface ripples ...
  • 07:41: ... vortices are fantastic laboratories for spinning black holes in particular. Now we’ve looked deeply into rotating, or Kerr black ...
  • 08:04: ... thing we saw was that rotating black holes can donate some of their rotational energy to particles or waves that ...
  • 10:13: ... as with real black holes, some atoms do escape as Hawking radiation. Here you can measure not just ...
  • 10:44: ... optical analogs are at best, approximations of the dynamics at play with black holes. ...
  • 11:04: ... crux of the matter is as much philosophy as physics: How much can analog black holes actually tell us about real black holes? Early arguments in the late ...
  • 12:12: They say black holes are unique aberrations, and analog is just that: an imperfect analogy incapable of truly capturing the extreme dynamics at play.
  • 12:23: ... able to travel to the stars, or to build - and hopefully control - real black holes in the lab, the black hole analog is the best physical experiment we can ...
  • 12:34: ... pull from the bathtub vortex may give us the next great insight into black holes, Hawking radiation, and the nature of the underlying, you guessed it, ...

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

  • 07:06: ... all stars will die and their remnants will decay - black holes will evaporate by Hawking radiation, and particles of matter will decay ...
  • 12:48: To do that, black holes must swallow entropy - and destroy information.
  • 13:28: Penroses proposes that the collisions of super massive black holes in the previous universe may leave rings on the sky in the next.
  • 14:09: ... advanced civilization could manipulate the dances of gigantic black holes, they could potentially send information between ...
  • 14:49: ... names encoded in the orbital frequencies of colliding suppermassive black holes at the end of time to be propogated across the conformal infinity into ...

2020-05-27: Does Gravity Require Extra Dimensions?

  • 07:52: ... John Mitchell - the same guy who first hypothesized the existence of black holes. ...
  • 13:49: ... his hunch which is that the “multiverse” you get from traveling through black holes has nothing to do with the multiverse predicted by quantum ...
  • 15:16: And in the case of the black holes, several unreasonable assumptions allow us to trace geodesics into alternate universes.

2020-05-18: Mapping the Multiverse

  • 01:33: Now, we’re going to focus on rotating black holes here, but a lot of this also applies to charged black holes, as we’ll see.
  • 04:06: But now as we fall the outward pressure due to the black hole’s rotation starts to win against that inward flow.
  • 09:10: That’s a little confusing because black holes are supposed to be inescapable.
  • 12:58: This whole counter-streaming instability thing was figured out by Roger Penrose in the context of charged, non-rotating black holes.
  • 13:08: But it almost certainly applies to Kerr black holes also because the two are very similar.
  • 13:13: ... electrically charged, or Reissner-Nordström black holes the electromagnetic field within causes massive tension, or negative ...

2020-05-04: How We Know The Universe is Ancient

  • 14:28: Devansh Rana asks Can wormholes exist without black holes ie without the event horizon.

2020-04-28: Space Time Livestream: Ask Matt Anything

  • 00:00: ... community tab asks if I can describe how dark energy and evaporating black holes with virtual particles do not violate conservation laws so let's start ...

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

  • 00:23: ... - a solution that we now understand describes a black hole. But before black holes were ever taken seriously, the Schwarzschild solution revealed the ...

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

  • 00:47: ... four million times the mass of the Sun, but it also swarms with smaller black holes, searing hot clouds of gas, massive stars right on the edge of going ...
  • 01:49: ... researchers in the field believe that all supermassive black holes went through violent AGN phases in the past — and that includes our very ...
  • 07:43: All of those supernovae would have had to leave remnants behind - neutron stars and black holes.

2020-03-31: 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 ...
  • 00:10: ... simply end inside the black hole, but continue beyond. In these maps, black holes become wormholes, and new universes lie on the other ...
  • 03:14: ... at the poles, to cancel out the converging lines of longitude. For black holes we instead fuse time with a something called a tortoise coordinate, ...
  • 08:44: ... for now you overtake that light and get a glimpse of the black hole’s past. You never actually see the singularity - that is manifest as an ...
  • 10:30: Not only is faster than light travel impossible, but eternal black holes don’t exist either.
  • 10:35: ... hole in order for geodesics to have somewhere to come from. But real black holes form from collapsing stars - there’s no white hole in their past. And ...
  • 10:58: ... instant travel between distant locations. And in the case of rotating black holes, the traversable wormhole and even the parallel universe are not so easy ...
  • 11:37: ... we’re doing comments for the last two episodes which are on rotating black holes and quantum darwinism. Let’s see what you had to ...

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

  • 01:01: ... observations of the universe have since told us that black holes are very real. We’ve seen the gravitational waves caused by their ...
  • 01:35: According to the no-hair theorem, black holes can have three and only three properties: mass, electric charge, and spin.
  • 01:44: ... mass. Compacting a lot of mass into a tiny region is what makes them black holes in the first place. Essentially no black holes have electric charge - if ...
  • 02:26: ... black holes might not have MUCH spin - because angular momentum can cancel out if ...
  • 02:36: ... the importance of spin in black holes, it took nearly half a century before Einstein’s equations were solved ...
  • 03:27: ... a rotating black hole. We’ll save the even weirder details of the Kerr black hole’s interior for another episode. For a preview check out our episode on ...
  • 04:26: ... Black holes are self-sustaining holes in the fabric of spacetime. Space at the event ...
  • 07:27: So yeah, you can orbit “safely” pretty close to the Kerr black hole’s event horizon.
  • 07:33: ... That means everything - even light - must move in the direction of the black hole’s ...
  • 09:37: ... is extracted from the rotational energy in the ergosphere, slowing the black hole’s spin. To get a little more technical - it works because the weird ...
  • 10:51: ... the black hole. It’s hypothesized that some jets observed from accreting black holes may be powered by this ...
  • 11:31: ... produced by fast-rotating black holes are also a contender for another astrophysical phenomenon - gamma ray ...
  • 12:11: ... black holes are very real and powerful players in the energetics of our universe - ...

2020-02-18: Does Consciousness Influence Quantum Mechanics?

  • 14:37: This is a great image - galaxies falling apart as they turned into black holes and other stellar corpses.

2020-02-03: Are there Infinite Versions of You?

  • 07:55: ... be prohibited by a combination of conservation laws and the formation of black holes. ...

2020-01-27: Hacking the Nature of Reality

  • 13:58: ... so previously we talked about a compelling new idea for how black holes might merge - perhaps they're captured and then brought together in the ...
  • 14:50: Adam Wulg asks whether gas surrounding a pair of merging black holes might significantly affect the gravitational wave signature.
  • 15:01: ... causes the black holes to merge faster, so that should increase the frequency of the those ...
  • 15:10: ... all gas is going to be ejected from the near region of these merging black holes before they actually collide, and LIGO only sees the merger in the last ...
  • 15:37: ... it's oxymoronic to say that “All you need is a little quasar" to catch black holes. Suggesting that there's no such thing as a little ...
  • 15:56: ... quasars our powered by supermassive black holes a few tens of millions to 10 billion times the mass of the sun - and the ...
  • 16:14: ... accretion disks are still very capable of capturing even smaller black holes - and may in fact be better at it because densities can be higher in the ...

2020-01-20: Solving the Three Body Problem

  • 11:21: ... of dense regions of the universe, where three-body systems of stars or black holes may form and then disintegrate very ...

2020-01-13: How To Capture Black Holes

  • 00:00: ... black holes are awesome, but how about black holes being captured by the screaming ...
  • 00:24: ... - LIGO - detected its first gravitational wave from the merger of two black holes. That was stunning enough, but the real promise lay ahead. Every time we ...
  • 00:59: ... with each other, they may end their lives to leave a pair of binary black holes. And in very dense environments like the cores of galaxies, lone black ...
  • 01:54: ... there was some striking surprises. For one thing, many of the merging black holes were too massive to have been formed by the collapse of stellar cores. ...
  • 02:16: ... what if black hole mergers actually occur in orbit around supermassive black holes, embedded deep in the whirlpools of searing gas that surround some of ...
  • 02:50: ... also contains a swarm of perhaps tens of thousands of stellar-mass black holes. These are the remnants of dead stars, typically a few to a few tens ...
  • 03:34: ... sounds like a recipe for black hole collisions. Actually not so much - black holes are so compact that they never collide outright - they need to merge by ...
  • 04:08: ... there’s a way to massively accelerate the mergers of these black holes: all you need is a little quasar. For the most part the supermassive ...
  • 04:50: ... is how supermassive black holes can grow to such enormous sizes, but what does the presence of an ...
  • 05:37: ... these disk-crossing black holes should be swept into the accretion disk. There they gorge on the gas of ...
  • 06:15: ... accretion disks also allow lone black holes to find each other. This is really cool, because the process is similar ...
  • 07:17: ... build into planets. In the case of accretion disks, the “planets” are black holes - captured single black holes end up in the same migration trap, ...
  • 08:50: ... test? That’s where the paper by McKernan and collaborators comes in. If black holes merge in empty space then the event should invisible - it should emit no ...
  • 09:21: ... it can carry away up to several percent of the original mass of the two black holes. ...
  • 11:32: ... mysteries and strange phenomena. Now we have the amazing possibility of black holes merging and growing to enormous size while trapped within the blazing ...
  • 11:59: ... selection - Lee Smolin's idea that maybe new universes are born inside black holes. ...
  • 12:49: ... couple of you point out that the idea of black holes birthing universes still doesn't explain where the first ...
  • 14:13: ... people also commented that they'd thought of the whole black holes creating new universes thing independently to Lee Smolin. I'm making a ...

2019-12-17: Do Black Holes Create New Universes?

  • 02:02: Those daughter universes go on to expand and make their own black holes and hence their own daughter universes.
  • 02:20: Some of those shifts improve the daughter universe’s ability to form new black holes.
  • 02:25: ... gradually the ensemble of all universes get better and better at making black holes, just as biological organisms with helpful mutations can get better at ...
  • 02:43: Now by happy chance there’s a correlation between making lots of black holes and making life - both require stars.
  • 03:12: First up, for any of this to make sense black holes need to create universes.
  • 05:14: ... very quickly be dominated by ones that are extremely good and making black holes. ...
  • 05:36: ... optimal in a given universe, at least for a given mechanism for making black holes. ...
  • 05:49: In our modern universe, black holes are made when the most massive stars explode as supernovae.
  • 05:56: There are other ways to make black holes, and we’ll come back to them.
  • 07:00: ... water, and chemistry in general, far fewer stars and so far fewer black holes would form - and of course these factors also seem to be essential for ...
  • 07:12: But what about other sources of black holes?
  • 07:16: ... the distant future, quantum fluctuations of that near vacuum will cause black holes to spontaneously appear - and given infinite time these will eventually ...
  • 07:38: ... all this is true then the most black holes would be produced by the biggest universes - more space means more ...
  • 08:22: This would lead to multiple branches of the cosmic genetic tree - some of which correspond to producing lots of stellar black holes.
  • 09:20: Black holes only form when the neutron stars is above a certain mass limit.
  • 09:48: That in turn means less massive neutron stars would be able to collapse into black holes.
  • 09:54: ... then, if universes evolve to maximize the number of black holes, then the strange quark mass should be optimized to make the cutoff ...

2019-11-18: Can You Observe a Typical Universe?

  • 06:01: ... life in a state of extreme disorder and high entropy - iron stars, black holes, and a mist of cold elementary particles, not very hospitable to ...

2019-11-11: Does Life Need a Multiverse to Exist?

  • 12:21: ... Lee Smolin’s idea that universes are born when black holes form, with each new universe having slightly different fundamental ...

2019-10-21: Is Time Travel Impossible?

  • 04:41: ... ways they might – from connections between universes in the interiors of black holes to miniscule wormholes appearing and vanishing on the tiniest scales of ...
  • 05:06: They collapses on themselves instantly, leaving inescapable black holes.

2019-10-15: Loop Quantum Gravity Explained

  • 16:02: ... expected to be impossible, and so we expect a maximum rotation rate for black holes. The details of all this need their own episode, so I'll leave it at ...

2019-10-07: Black Hole Harmonics

  • 00:04: ... Black holes are crazy enough on their own – but crash two together and you end up ...
  • 00:41: ... physicists talk about black holes they’re usually referring to highly theoretical objects – static, ...
  • 01:00: But real black holes are created in the violent deaths of massive stars, and there’s nothing clean about that.
  • 01:08: ... now know that black holes also merge – and in the process produce gravitational radiation that ...
  • 01:43: Technically, in that instant we go from two black holes to one.
  • 02:14: ... two inspiralling black holes make powerful spacetime ripples – gravitational waves – which intensify ...
  • 03:46: The harmonic oscillations of 2-D surfaces – like drum skins, bells, or the event horizons of black holes – are a good bit more complex than in 1-D.
  • 05:53: ... relativity and, among other things, telling it to collide thousands of black holes. ...
  • 07:22: ... found that they could pinpoint the mass and spin of the simulated black holes with much greater precision than if they’d just used the gravitational ...
  • 08:09: ... in fact, was also the first one LIGO reported: GW150914 – a pair of black holes, each 30 or so times the mass of the sun, spiraling into each other one ...
  • 09:05: .69 means this is a rapidly rotating black hole, which is unsurprising seeing as it just absorbed the orbital angular momentum of two black holes.
  • 09:44: General relativity predicts that black holes should be completely defined by three properties – their mass, spin, and electric charge.
  • 10:01: And this is the no-hair theorem – black holes have no hair.
  • 10:08: ... astrophysical black holes are also expected to have no electric charge, so mass and spin should ...
  • 12:29: ... hard to come up with a plausible explanation for why two pairs of binary black holes should merge near each other at the same ...
  • 12:52: We’re seeing many, many mergers of black holes and neutron stars, and we’re learning an awful lot about these objects.
  • 12:59: ... wave spectroscopy, we can now listen to the harmonics of ringing black holes, and through them better understand the fundamental nature of extreme ...

2019-09-23: Is Pluto a Planet?

  • 01:00: ... classify galaxies based on their shape, black holes based on how they feed and how they're oriented, stars based on their ...

2019-07-25: Deciphering The Vast Scale of the Universe

  • 08:16: ... see these most distant quasars, as well as the earliest galaxies or even black holes or worlds around other stars, Mt. Wilson's Hooker Telescope wouldn't cut ...

2019-07-18: Did Time Start at the Big Bang?

  • 11:12: ... lead to all particles randomly converging back to the same spot Or maybe black holes birth new universes as in Lee Smolin's "Fecund Universe" ...

2019-07-01: Thorium and the Future of Nuclear Energy

  • 15:29: ... further futures in space-time In a recent episode we talked about how black holes influence the galaxies they formed in often by killing them Let's see ...
  • 16:45: ... full blown quasars the most luminous of accreting black holes or active galactic nuclei are Typically in bowl-like elliptical ...
  • 16:59: ... isn't so important. Proghead777 asks, whether the central supermassive black holes gravitational Influence is extended by frame dragging Well, the answer ...
  • 17:49: ... objects orbit in the same direction as a black hole's rotation that can be stable much closer in but if they orbit in the ...

2019-06-17: How Black Holes Kill Galaxies

  • 00:00: Thanks to Brilliant.org for supporting PBS Digital Studios Black Holes are really only dangerous if you get too close Who am I kidding ?
  • 00:08: ... Star formation across the entire Universe When we first realized that Black Holes could have masses of Millions or even Billions of times that of the Sun ...
  • 01:35: ... connected A couple of things you need to know Even though Supermassive Black Holes are Big they're peanuts compared to the Galaxies they live in their ...
  • 02:54: ... extreme star formation called Star Busts as galaxies grew so did their Black Holes they would've started as a ready mass of seed Black Holes formed by the ...
  • 04:05: ... process seems to be Second Observation seem to indicate that early Black Holes actually grew faster than their surrounding galaxies The 'Galaxy Black ...
  • 05:14: ... the best contender is that the black holes kill galaxies and by "kill" , I mean make them dead which I guess is the ...
  • 07:21: ... puffed up as well as killing star formation quasar activity limits the Black Hole's own growth it grows relating the new supply of gas but then its energy ...
  • 10:49: ... modern universe Giant Dead galaxies harbor fossil quasars supermassive Black Holes whose close connection to their surrounding galaxy is a clue ...

2019-06-06: The Alchemy of Neutron Star Collisions

  • 02:47: ... fact that they are on the verge of complete gravitational collapse into black holes so take a pair of neutron stars in binary orbit perhaps twin remnants of ...

2019-05-16: The Cosmic Dark Ages

  • 06:54: ... elements. Stars that large and luminous burn out fast and leave behind black holes. These ravenous stellar corpses found themselves in an all-you-can-eat ...
  • 07:19: ... were born the first supermassive black holes with millions, even billions of times the Sun’s mass – inescapable ...

2019-05-09: Why Quantum Computing Requires Quantum Cryptography

  • 14:57: AspLode asks about the interaction between dark matter and black holes.
  • 15:04: ... is some sort of exotic particle - which is the going hypothesis - then black holes would definitely attract dark matter gravitationally, and occationally ...
  • 15:27: Occasional dark matter particles would be snared by black holes - and they would add to its mass just like regular matter.

2019-05-01: The Real Science of the EHT Black Hole

  • 05:15: So black holes are, of course, black.
  • 10:33: ... then when black holes emerged from Karl Schwarzschild’s solution to the Einstein equations, ...
  • 11:22: ... of the late, great Hawking, as well as everything from the Big Bang to Black Holes. ...

2019-04-24: No Dark Matter = Proof of Dark Matter?

  • 00:03: ... dark compact bodies like failed stars or stellar corpses or primordial black holes then we'd see the warping of of more distant stars in their ...

2019-04-10: The Holographic Universe Explained

  • 01:19: The story started with black holes, and with Jacob Bekenstein, who derived an equation to describe their entropy.
  • 01:27: A black hole’s entropy represents the amount of quantum information of everything that ever fell into it.
  • 11:58: ... strong gravitational fields in the higher dimensional space – like in black holes – look like a solvable configuration of particles in the low-D ...

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

  • 04:49: The first efforts were designed to allow physicists to cross the event horizon of black holes – mathematically.
  • 15:32: Many of you asked what happens to black holes in the big rip.
  • 15:39: So I thought that the answer was that black holes would be eroded into nothing.

2019-03-28: Could the Universe End by Tearing Apart Every Atom?

  • 12:53: ... a long cold heat death in which the stars of our galaxy wink out become black holes and then evaporate over an unthinkably long future. But maybe if you ...

2019-03-20: Is Dark Energy Getting Stronger?

  • 15:02: ... deeper into astrophysics, then you'll want to check out the course: Black Holes, Tides, and Curved Spacetime: Understanding ...

2019-02-07: Sound Waves from the Beginning of Time

  • 13:58: ... 10^(10^25) years for the first quantum tunneling to turn iron stars into black holes, and way, way longer than that for anything ...

2018-11-07: Why String Theory is Right

  • 03:01: It doesn't give you tiny black holes when you try to describe gravity on the smaller scales.
  • 03:07: ... worth taking a moment to see how stringy gravity avoids the problem of black holes. ...
  • 04:15: If you even try to describe very strong gravitational interactions, you get nonsense black holes in the math.

2018-10-31: Are Virtual Particles A New Layer of Reality?

  • 00:21: Near black holes, virtual matter and antimatter pairs are separated by the event horizon to create Hawking radiation.

2018-10-18: What are the Strings in String Theory?

  • 09:10: ... smaller scales, the energies required to interact on that scale produce black holes. ...
  • 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.
  • 14:59: But most of the information in the universe is in black holes, or more accurately, most entropy or hidden information is in black holes.
  • 15:07: So our black hole computer can't contain the information hidden in all black holes.
  • 15:12: It can't even contain the information from black holes larger than itself.
  • 15:57: Like I said, our black hole computer is only simulating particles, not black holes.

2018-10-10: Computing a Universe Simulation

  • 03:16: ... was in studying black holes that Jacob Bekenstein realized that they must contain the maximum ...
  • 06:20: But remember, we're storing all of the information in the universe on just one of these black holes.
  • 10:26: ... can only read out the simulation results in Hawking radiation as those black holes evaporate, which will take 10 to the power of 70 years minimum-- hell of ...

2018-10-03: How to Detect Extra Dimensions

  • 01:22: Unlike merging black holes, which are invisible, merging neutron stars explode spectacularly.
  • 14:43: ... mechanics are both right, then we should have Planck-length virtual black holes popping into and out of ...

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

  • 03:33: ... black holes of pure general relativity swallow information in a way that can remove ...
  • 03:54: ... 't Hooft and others, it has become clear that information swallowed by black holes can be radiated back out into the universe via their Hawking ...
  • 07:33: Particles whose positions are defined within a Planck length can spontaneously become black holes.
  • 07:39: Of course, those black holes don't really happen.
  • 11:09: The non-renormalizability of quantized general relativity is connected to the idea that precisely localized particles produce black holes.
  • 12:46: ... thanks, we're sending you a box of chocolate-covered Planck-scale black holes. ...
  • 13:20: A few of you asked why it is that the surface area of a black hole's event horizon must always increase and how mass and radius can actually decrease.
  • 13:30: When two black holes merge, a lot of energy is pumped into gravitational waves.
  • 13:35: There's only one place for that energy to come from, the mass of the black holes.
  • 13:54: Note that the final black hole is both more massive and larger than either of the original black holes taken separately.
  • 14:22: But rotating black holes are slightly squished.

2018-09-12: How Much Information is in the Universe?

  • 00:25: ... then there's all the stuff that isn't stars-- the dark matter, black holes, planets, and the particles, and radiation in between the stars and ...
  • 06:58: But there's one more source of information-- black holes.
  • 07:02: As I mentioned last time, black holes contain most of the entropy in the universe.
  • 07:25: And for black holes, that entropy is the Bekenstein bound, the number of Planck areas on its event horizon.
  • 07:32: Because the information about the black hole's previous state is lost, to fully describe it, you need to fully describe its event horizon.
  • 08:26: Black holes contain, by far, most of the entropy in the universe, and require most information to fully describe.
  • 09:17: The Bekenstein bound does apply equally to engineered information storage as it does to black holes and universes.
  • 09:56: Let's ignore really high entropy stuff like black holes, the cosmic background radiation, and neutrinos.

2018-09-05: The Black Hole Entropy Enigma

  • 00:07: Black holes seem like they should have no entropy, but in fact they hold most of the entropy in the universe.
  • 00:15: [MUSIC PLAYING] At first it seemed that black holes were so simple they should have no entropy.
  • 00:34: Black holes are a problem.
  • 00:46: That theory is one of the most thoroughly tested in all of physics, which means we should probably believe in black holes.
  • 01:01: And yet if black holes exist, which apparently they do, they contradict other theories in physics that are as sacred as general relativity.
  • 01:21: It was while pondering that conflict that Jacob Bekenstein realized an incredible connection between black holes and thermodynamics.
  • 01:42: But first, you are going to need to know more about why black holes contain most of the universe's entropy.
  • 01:59: We're also rewinding to the late '60s, early '70s when physicists realized something odd about black holes.
  • 02:08: From the point of view of the outside universe, black holes can only have three properties-- mass, spin, and electric charge.
  • 02:30: ... if black holes evaporate, as Hawking discovered and we also covered, this evaporation ...
  • 04:26: How does this relate to black holes?
  • 05:49: ... law that got Jacob Bekenstein thinking about the connection between black holes and information in the first ...
  • 06:09: So you know how nothing can escape black holes, ignoring Hawking radiation for the moment.
  • 06:14: That should mean that black holes can only grow.
  • 06:22: If you merge two black holes, some of their mass gets converted to the energy radiated away in gravitational waves.
  • 06:40: Gravitational radiation and the Penrose process reduce black-hole mass and radius or the sum of masses and radii of emerging black holes.
  • 06:48: But there's one property of black holes that no process other than Hawking radiation can decrease.
  • 06:56: Do anything to black holes and their total surface area can only grow or stay constant.
  • 09:04: He showed that black holes radiate random particles exactly as though they have a peak glow for a particular temperature that depends on their mass.
  • 09:13: So if black holes have a temperature, then they also have entropy.
  • 10:01: The second law of thermodynamics is saved because black holes do have entropy.
  • 10:06: In fact, they have enormous entropies, the maximum possible, so much that black holes are now believed to contain most of the entropy in the universe.
  • 10:25: Bekenstein's formula was derived for black holes, but it also gives the maximum amount of information that can be fit into any volume of space.

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

  • 02:32: ... of nothing but stellar remnants, the ultradense neutron stars and black holes from long-extinct massive stars, as well as the white dwarfs left from ...
  • 05:28: Heavier bodies, mostly neutron stars and black holes, sink towards the center.
  • 06:58: The universe will contain only photons, electrons, and black holes.
  • 07:06: If protons decay, black holes would be the only mass of bodies left in the universe after 10 to the power 40 years.
  • 07:13: Some will be the remnant black holes of individual stars that were flung from galaxies long ago.
  • 07:18: But most of the black hole mass will be in supermassive black holes.
  • 07:38: But all black holes evaporate over time via Hawking radiation, something we've discussed in detail.
  • 07:51: The small black holes, say, around 10 times the mass of the sun, completely evaporate in around 10 to the power of 67 years.
  • 07:58: The largest supermassive black holes that might ever form will take a little longer, up to 10 to the power of 106, or a million googol, years.
  • 08:14: ... Black holes themselves can be used as engines through Hawking radiation, as we've ...
  • 08:38: ... stellar remnants during the Degenerate Age and, ultimately, end up in black holes. ...
  • 08:52: But even black holes must end.
  • 08:55: Occasional flashes of gamma rays will light up the darkness as black holes reach that last explosive stage of their evaporation.
  • 09:33: Black holes evaporate.
  • 10:50: It depends on how small black holes can really be.
  • 10:53: ... small, stable black holes are possible, then quantum tunneling should allow small regions within ...

2018-06-20: The Black Hole Information Paradox

  • 00:22: [MUSIC PLAYING] Black holes are engines of destruction that remove from our universe anything that crosses their event horizon.
  • 01:27: In recent episodes, we've explored some critical facts about the universe and about black holes.
  • 01:54: It states that black holes can only exhibit three properties-- mass, electric charge, and angular momentum.
  • 02:44: ... causes black holes to evaporate into a perfectly random buzz of radiation that contains ...
  • 03:25: ... Black holes should radiate as though they have a temperature that is inversely ...
  • 10:20: But to enter the game, Hawking had to concede the old bet and admit that information does escape black holes.
  • 11:22: ... cute little 1974 paper in which the young Stephen Hawking showed that black holes must leak very slightly has led to radical new ideas about the nature of ...
  • 11:41: Black holes represent the ultimate victory of gravity.
  • 11:50: But the first hint of the existence of black holes appeared long before Einstein.
  • 12:01: So, to continue your own mathematical journey into black holes, Newton's gravity is the place to start.
  • 12:45: Last week we talked about the no-hair theory of black holes, and you all had some hairy questions.
  • 13:53: ... we talked about a black hole's electric charge in terms of the classical electromagnetic field which ...

2018-06-13: What Survives Inside A Black Hole?

  • 00:16: ... PLAYING] We've established by now that black holes are weird, the result of absolute gravitational collapse of a massive ...
  • 00:49: These ideas are pretty mind blowing, but as crazy as black holes are, they're also kind of simple.
  • 01:21: ... we're get to see why black holes are bold, and in an upcoming episode we'll combined the no-hair ...
  • 01:56: Or as Bekenstein put it, black holes have no hairs.
  • 06:12: Black holes act as though their charge is spread across the event horizon.
  • 07:59: ... hole, nothing can get out, but new infalling material will adjust the black hole's external gravitational and electric fields on its way ...
  • 08:08: By the way, it's worth mentioning that real black holes out there in the universe are never going to have a net electric charge.
  • 08:46: In a similar way, you can see a black hole's rotation in its gravitational field.
  • 10:45: Yet Stephen Hawking showed that black holes may break this rule, revealing a conundrum that we now call the information paradox.
  • 10:54: The solution to the information paradox is highly speculative, but it may reveal that black holes are more hairy than we thought.
  • 13:48: Second, as we'll see next week, even black holes probably preserve information.

2018-05-23: Why Quantum Information is Never Destroyed

  • 01:23: In a future episode, we'll see how this law might be broken by black holes.
  • 09:50: That's the case of black holes and Hawking radiation.

2018-05-09: How Gaia Changed Astronomy Forever

  • 09:44: A popular one seems to be, rotating black holes or harvesting Hawking radiation from black holes.
  • 09:52: Super advanced civilizations clustered around black holes, in an utterly dark universe.

2018-05-02: The Star at the End of Time

  • 08:55: Last week, we talked about a swarm of black holes recently discovered in the core of the Milky Way.
  • 09:34: Yeah, dark matter is expected to be more evenly spread through the galaxy than things like stars and black holes.
  • 09:54: ... black hole in our galaxy center is in itself a dense swarm of smaller black holes in a shared orbit amounting to the same total ...
  • 10:21: There certainly couldn't be millions of stellar-mass black holes.

2018-04-25: Black Hole Swarms

  • 00:07: It's been conjectured that the center of the Milky Way contains not one, but a vast swarm of black holes, and now, we've actually seen them.
  • 00:58: ... years of the Milky Way is thought to contain a vast swarm of smaller black holes that have reigned in from the surrounding ...
  • 01:07: ... that our own Milky Way core is packed with hundreds, maybe thousands, of black holes. ...
  • 01:28: ... get to how they found these black holes in a minute, but first, I want to ask, why did so many astrophysicists ...
  • 01:56: And the densest, stellar objects, like black holes, sink to the centers of galaxies or star clusters.
  • 02:01: We think black holes must gradually sink to the center of the Milky Way, although, the exact process is a wee bit more complicated.
  • 02:11: Black holes form when the most massive stars end their lives in spectacular supernova explosions.
  • 02:26: ... expect the so-called stellar-mass black holes to weigh in at between five and 15 solid amasses, although, the recent ...
  • 02:37: Even after blowing off most of their mass in a supernova, these black holes are still heavier than most stars.
  • 03:33: Over a few billion years, we only expect the black holes from the central several light years to have made much progress inwards.
  • 03:40: However, there's another process that can really drive a huge number of black holes inwards.
  • 04:22: Those globular clusters must have been full of ancient black holes, which would be carried to the core with their parent cluster.
  • 04:30: Those black holes would then, sink even further to the center of the galaxy.
  • 04:34: ... been calculated that this process should lead to tens of thousands of black holes in the central few light years of the Milky Way's ...
  • 04:43: So how did Hailey and team spot these black holes?
  • 04:49: Black holes are effectively invisible, but things can be different if a black hole and a companion star are in a binary orbit around each other.
  • 05:32: But today, we're interested in black holes.
  • 05:56: Frequently enough that if the galactic core is full of black holes, then it should also contain quiescent X-ray binaries.
  • 07:08: ... quiescent X-ray binaries, which appeared to be the type powered by black holes. ...
  • 07:18: Now, 13 doesn't sound like a swarm, but remember, only a small fraction of black holes are seen as X-ray binaries.
  • 07:25: ... that there would need to be at least hundreds of stellar-mass black holes in the central few light years in order to get these 13 X-ray ...
  • 07:35: Now, that's tens of thousands of times the black hole density anywhere else in the galaxy so yeah, it's a swarm of black holes.
  • 08:05: ... black holes are so densely packed in the centers of galaxies, then we should ...
  • 08:24: ... black hole, but also, a swarm of hundreds, maybe thousands, of smaller black holes, in what has to be the craziest and most terrifying environment in nearby ...
  • 08:51: ... if we're talking about black holes, one of the most fun rides on CuriosityStream is brought to you by the ...

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

  • 00:55: The black holes in question were enormous.
  • 01:07: ... if these black holes formed in the deaths of massive stars, which we think they must, then ...
  • 01:16: It's hard to imagine black holes forming bigger than this or both of a binary pair growing this large after formation.
  • 01:30: Some are trying to adjust stellar evolution models to allow for the formation of more massive black holes.
  • 01:36: ... are calculating whether these black holes may have grown inside globular clusters, where the stellar density is so ...
  • 01:47: Perhaps we've observed the merging of primordial black holes formed in the instant after the Big Bang.
  • 03:35: ... to the frequency of the binary orbits just before merger, which for black holes and neutron stars clocks in at a few to maybe 1,000 orbits per second in ...
  • 03:49: ... catch the merger of the million to billion solar mass black holes, supermassive black holes that live in the centers of galaxies, we need ...
  • 04:34: ... will see those merging supermassive black holes, as well as the faint hum of thousands of binary pairs of white dwarfs, ...
  • 05:00: ... buzz from an earlier epoch of the universe in which binary supermassive black holes were common, or from cosmic strings, if they ...
  • 07:52: ... of galactic cores if those galaxies also contain binary supermassive black holes that are generating gravitational ...

2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)

  • 01:05: Black holes evaporate.

2018-04-04: The Unruh Effect

  • 00:00: [GENTLE MUSIC] Are you worried about black holes?

2018-03-28: The Andromeda-Milky Way Collision

  • 06:16: Meanwhile, the black holes lose angular momentum and fall towards the center.
  • 06:20: When those black holes are around a light year apart, they'll start losing orbital energy to gravitational waves.
  • 07:49: There's also a small chance that the sun will encounter one of the supermassive black holes as they descend to the core.

2018-03-21: Scientists Have Detected the First Stars

  • 02:38: ... a while, the first black holes formed, and started to spew out x-rays, as they gobbled up hydrogen. ...

2018-03-15: Hawking Radiation

  • 01:15: ... black holes should exist forever, only growing, never shrinking, or so we thought, ...
  • 01:31: ... a new union of quantum mechanics and general relativity to show that black holes should not be so black after ...
  • 04:25: Stephen Hawking knew that black holes with their insane spacetime curvature would wreak havoc on quantum fields in their vicinity.
  • 07:18: Black holes tend to scatter modes with wavelengths similar to their own sizes.
  • 07:47: Black holes should have a heat glow with an apparent temperature that depends on their mass.
  • 07:57: Large black holes should appear cold, radiating excruciatingly slowly.
  • 08:01: But small black holes should appear hot.
  • 10:48: Whichever way you interpret it, it's hard to avoid the conclusion that black holes emit particles.
  • 11:28: How do they end up reducing the black hole's mass, instead of increasing it?
  • 11:44: For now, we must conclude that black holes radiate and in doing so evaporate.

2018-01-31: Kronos: Devourer Of Worlds

  • 01:49: ... including the numbers of near-invisible stellar objects like black holes and neutron stars, as well as the distribution of gas and dark ...

2018-01-24: The End of the Habitable Zone

  • 10:29: In no time at all you'll be coding gravity simulations in Python and calculating the radiation emitted by black holes.

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

  • 09:53: In no time at all, you will be coding gravity simulations in Python and calculating the radiation emitted by black holes.

2017-12-22: Space Time VR

  • 00:27: Three experiences are out now, and three more covering general relativity, black holes, and the shape of the universe, are on the way for early 2018.

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

  • 12:16: And some stars will be sling-shotted out of the galaxy by the two supermassive black holes of Andromeda and the Milky Way as they fall together.

2017-10-25: The Missing Mass Mystery

  • 12:21: ... faster than the speed of light, can't they escape the event horizon of black holes via Hawking ...

2017-10-11: Absolute Cold

  • 08:26: ... about the new observation of a potential pair of binary supermassive black holes orbiting only one light year ...
  • 08:54: We know for sure that supermassive black holes do emerge, otherwise, they could never have got so big.
  • 09:31: ... there to be a good number of stellar remnants, like neutron stars and black holes, that have fallen towards the center from the surrounding ...

2017-10-04: When Quasars Collide STJC

  • 00:15: And stellar mass black holes rip neutron stars to shreds.
  • 00:20: But supermassive black holes eat all of the above breakfast.
  • 00:24: So what happens when two gigantic black holes tango?
  • 00:38: ... to dig into a paper that reports the detection of a pair of supermassive black holes orbiting only one light-year apart from each ...
  • 01:07: Studying the dance of these giants should tell us a ton about how black holes grow.
  • 01:25: Before we get to this new result, let's talk about supermassive black holes-- SMBHs.
  • 01:55: We're still figuring out how supermassive black holes got so big.
  • 02:26: In fact, this new observation may turn out to be a pair of supermassive black holes as close to merger as we've ever witnessed.
  • 03:12: Now, the purported binary black holes in this new study were found in a known Seyfert galaxy.
  • 03:26: Let's talk a bit about how these binary black holes were found, because it wasn't easy.
  • 03:38: The black holes are around one light-year apart in the center of the galaxy.
  • 04:39: Those two hot spots are the locations of the possible black holes.
  • 04:43: Now, black holes themselves are invisible.
  • 05:23: Now, this map alone doesn't tell us that there are two black holes.
  • 05:46: Here, we can see two bright spots far from the black holes, presumably from a burst of jet activity some time ago.
  • 05:54: So how do we know that the hot spots in the core are from two unique black holes instead of a lumpy jet from one black hole?
  • 06:54: The only way this is possible is with two separate black holes, each one powering its own mini quasar.
  • 07:01: OK, let's assume the researchers are right, and we've spotted supermassive black holes in a tight binary dance.
  • 07:30: Basically, the black holes slingshot stars outwards through gravitational interactions.
  • 07:44: You can think of it as a sort of gravitational friction dragging the black holes downwards and towards each other.
  • 07:51: However, by the time the black holes are only a few light-years apart, there shouldn't be any stars left in between them.
  • 08:04: In fact, we still don't know how supermassive black holes merge once they're within one parsec, or a few light-years, of each other.
  • 08:37: Can't gravitational radiation cause supermassive black holes to merge, just like it does with regular stellar mass black holes?
  • 09:38: Longer exposure radio observations will pin down the energy distribution to confirm whether these really are jets produced by two black holes.
  • 09:54: However, careful observations of the stars in the galaxy can help us figure out the masses of the black holes and look for signs of galaxy mergers.
  • 10:08: ... leading us closer to understanding the incredible growth of the largest black holes in all of ...
  • 10:44: We will spend it exclusively on animating black holes and quasars, and also pizza.

2017-09-28: Are the Fundamental Constants Changing?

  • 06:37: Remember quasars, insanely luminous maelstrom drums of superheated matter surrounding the most massive black holes in the universe?

2017-09-20: The Future of Space Telescopes

  • 08:19: However, it would be able to see x-rays right down to the event horizons of super massive black holes in distant galaxies.

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

  • 00:06: Last year, LIGO announced the detection of gravitational waves from the merger of two black holes.
  • 00:37: ... Observatory, LIGO, detected gravitational waves from a pair of merging black holes, an entirely new realm of the universe opened up to ...
  • 01:04: As the data comes in, we're learning a ton about black holes, how they grow, and the stars that produce them.
  • 01:10: But the merger of binary black holes isn't the only game in town.
  • 03:38: Any neutron stars or black holes in close orbit with each other will eventually collide as they leave gravitational radiation.
  • 03:56: Well, because the universe makes far more neutron stars than black holes.
  • 04:00: See, black holes only form in the deaths of the most massive stars, those over approximately 20 times the Sun's mass.
  • 04:18: That means neutron stars should be more common than black holes and neutron star binary systems should merge more often than black whole binaries.
  • 04:39: But that's a factor of 10 smaller than the 30 solar mass black holes that merged in the first LIGO detection.
  • 05:37: ... black holes only hit that range in the final second before merger, while neutron ...
  • 08:03: We rarely see supernovae from this galaxy type because their most massive stars have long since exploded to leave neutron stars and black holes.

2017-08-30: White Holes

  • 00:14: In fact, it's the black hole's mirror twin-- the white hole.
  • 00:50: ... have since demonstrated that black holes are very real with convincing evidence that quasars, x-ray binaries, ...
  • 02:26: White holes first emerged in the very earliest mathematical description of black holes.
  • 05:17: If we place an eternal black hole far to the left, then the future left boundary represents the black hole's event horizon.
  • 08:27: The universe hasn't existed for eternity, and it didn't even begin with black holes in place.

2017-05-31: The Fate of the First Stars

  • 00:13: The resulting swarms of supernova explosions enriched the universe with the first heavy elements and lots of black holes.
  • 08:51: These enormous stars are also thought to have left behind enormous black holes when they died.
  • 09:04: ... of giant stars become clusters of giant black holes, which, in turn, would merge into monsters of thousands or tens of ...
  • 09:15: ... these were probably the seeds of the so-called supermassive black holes, with millions to billions of times the mass of the sun, that we find ...
  • 09:26: Such black holes power quasars, which themselves, had a huge influence on the later evolution of our universe.

2017-04-26: Are You a Boltzmann Brain?

  • 05:30: The black holes will evaporate, the last proton will decay, and all of that cool stuff will cease.

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

  • 00:49: First we'll think about what the flow of time looks like without black holes or even spacetime curvature.
  • 08:54: We can try to move towards either source of light, down towards light from the black hole's past or up towards light from the black hole's future.

2017-02-02: The Geometry of Causality

  • 00:32: Recently, we've been talking about the weirdness of spacetime in the vicinity of a black hole's event horizon.
  • 12:07: ... way out of the mathematical singularity at the center of black holes is with string theory, which proposes that particles that we see in ...
  • 13:46: We see that these x-rays are stretched out as they climb out of the black hole's gravitational well.
  • 14:47: These giant black holes have been growing since the dawn of time by creating gas and by merging with other black holes.
  • 14:54: ... original seed black holes may have been left over by the deaths of an insanely large first ...
  • 15:13: "When my dad was in college, he needed one of those easy classes for credit, so he took a class on quasars and black holes in the universe.

2017-01-25: Why Quasars are so Awesome

  • 00:16: Let's talk about what happens when the largest black holes in the universe start to feed.
  • 04:16: That gas descends into the waiting black hole's gravitational well and gains incredible speed on the way.
  • 08:20: ... way into the nuclei of galaxies, it encountered there the supermassive black holes that had been growing since the beginning of the ...
  • 09:45: ... galaxy and the Milky Way inevitably collide and their supermassive black holes merge, the violence will deliver one last wave of fuel to the combined ...
  • 10:35: ... lectures on the nature of time in relativity, and its behavior around black holes. ...

2017-01-19: The Phantom Singularity

  • 02:09: Kelsey, the math for black holes goes to infinity for different properties and in different locations.

2017-01-04: How to See Black Holes + Kugelblitz Challenge Answer

  • 00:03: We've been talking a bit about black holes lately and we'll continue to do so.
  • 00:27: So to ground us a little bit first, I want to talk about actual real black holes, in particular, how we see these things.
  • 00:35: There's been no reasonable doubt about the reality of black holes for some time.
  • 00:46: The most spectacular effect is when black holes feed.
  • 00:50: ... will reach incredible speeds and temperatures, causing the region around black holes to ...
  • 01:00: This gives us things like quasars, supermassive black holes in galaxy cores that feed on a superheated whirlpool of gas.
  • 02:33: ... recent observations of gravitational waves from a pair of merging black holes by LIGO could be considered our first direct detection of black ...
  • 03:55: Interferometry is going to be used to study much smaller black holes in our galaxy, the remnants of dead stars.
  • 04:02: These black holes occasionally pass in front of more distant background stars, gravitationally lensing the star's light.
  • 04:28: ... over the next few years, we'll have mapped the space around black holes in ways that were once thought ...
  • 04:41: ... Black holes definitely exist, but these studies will be powerful tests of whether ...
  • 07:38: ... fun thing about black holes made this way is that the interior region-- that sad, doomed little ...

2016-12-21: Have They Seen Us?

  • 13:18: A couple of weeks ago, we looked back into black holes and studied the nature of the event horizon.
  • 14:55: But real black holes decay.
  • 16:06: First, let me note that I gave that statement in a list of popular examples of oversimplifications about black holes.
  • 16:31: ... event horizon, you need to travel at the speed of light relative to the black hole's stationary frame of reference as recorded by a distant ...

2016-12-14: Escape The Kugelblitz Challenge

  • 00:00: ... tool for understanding the strange space-time both in and around black holes. ...
  • 00:14: ... the one diagram the infinitely stretched space-time in the vicinity of a black hole's event ...
  • 00:44: ... that we discussed in the previous episode versus the real, astrophysical black holes that actually dwell out there in the ...

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

  • 00:29: Black holes, objects with densities so high that there's this region, the event horizon, where the escape velocity reaches the speed of light.
  • 01:34: It's a tool that will let us easily and so the most common questions about black holes.
  • 04:15: It crunches together, or compactifies, the grid lines to fit infinite space-time on one graph-- very useful for black holes.
  • 04:42: This is the Penrose diagram for flat space-time with no black holes.

2016-11-16: Strange Stars

  • 00:00: ... PLAYING] As if black holes and neutron stars aren't weird enough, physicists have very good reason ...
  • 00:44: The most wonderfully monstrous of these are the remnant corpses of the most massive stars, stellar zombies like neutron stars and black holes.

2016-10-19: The First Humans on Mars

  • 08:56: ... talked about the incredible, if speculative, possibility that primordial black holes formed in the insanely dense conditions right after the Big Bang and ...
  • 09:36: Black holes exhibit only three properties-- mass, electric charge, and spin.
  • 10:01: However primordial black holes don't form from stars and so aren't subject to this restriction.
  • 10:24: A few of you also asked whether the supermassive black holes that we find at the centers of galaxies could be primordial black holes.
  • 10:37: Those supermassive black holes started as much smaller seed black holes.
  • 10:54: ... like that idea because we see some pretty gigantic supermassive black holes in the early universe, and it's quite tricky to explain how they got ...
  • 11:07: Very large primordial black holes may help explain this, but there's no evidence for this idea.

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

  • 00:03: In the very first instant after the Big Bang, the density of matter was so great everywhere that vast numbers of black holes may have formed.
  • 00:12: These primordial black holes may still be with us.
  • 00:15: [MUSIC PLAYING] There's no longer any question that black holes exist.
  • 00:25: LIGO's recent observation of gravitational waves from merging black holes is a stunning confirmation of this fact.
  • 01:11: So why didn't all the matter in the universe become black holes then?
  • 01:15: Well, actually, some of it may have formed what we call primordial black holes, and they may still be around today.
  • 01:50: That means most of it avoided collapsing into black holes.
  • 02:19: These density fluctuations were enough to kick-start the formation of galaxies, but certainly not enough to immediately collapse into black holes.
  • 03:16: Some highly speculative Big Bang physics also predicts primordial black holes.
  • 03:29: Now, these models can predict a huge range of possible masses for primordial black holes-- PBHs, as we like to call them in the biz.
  • 04:05: We need to hunt for these black holes or their influence in the modern universe.
  • 04:10: First of all, we aren't going to find primordial black holes less than around a billion tons, or the mass of a small asteroid.
  • 04:25: Black holes larger than this should still be around, but they'd be very difficult to spot, being so black and all.
  • 04:43: Could primordial black holes be dark matter?
  • 04:48: This is a slightly terrifying possibility that 80% of the mass in the universe is in the form of countless, swarming black holes.
  • 04:59: That's a lot of primordial black holes, and so we expect them to leave their mark on the universe in different ways.
  • 05:39: There's also the fact that swarms of black holes would mess up their surroundings.
  • 05:53: The smallest should fall into neutron stars, causing them to either explode or become black holes themselves.
  • 06:07: These arguments let us rule out all but a very narrow set of mass ranges for primordial black holes as an explanation for dark matter.
  • 06:38: ... think that the voracious feeding of lots of really big primordial black holes would have left their mark on the cosmic microwave ...
  • 06:48: However, others argue that the recent LIGO detection of the merging of two approximately 30-solar-mass black holes is evidence in favor of this idea.
  • 07:07: ... too long, we'll either spot the signature of primordial black holes at these masses, or discover that PBHs are actually very rare, and that ...
  • 07:24: ... course, primordial black holes that have already evaporated due to Hawking radiation definitely are not ...
  • 07:58: It wouldn't be right to end a discussion on primordial black holes without talking about what would happen if one passed through the Solar System.
  • 08:30: Of course, regular black holes from supernovae can, and perhaps have, done that.
  • 08:36: Having high mass primordial black holes just makes it more likely.
  • 09:11: ... if primordial black holes have approximately the minimum possible mass to not have evaporated-- ...
  • 09:49: In fact, perhaps geologists will be the first to discover the primordial black holes.
  • 10:31: I found some amazing insights into the nature of black holes in Benjamin Schumacher of course Understanding Gravity.

2016-09-14: Self-Replicating Robots and Galactic Domination

  • 00:47: Even the unusual denizens of the galaxy like pulsars and black holes just do what they do.

2016-08-24: Should We Build a Dyson Sphere?

  • 07:22: ... from infalling material, or by extracting angular momentum from the black hole's ...
  • 08:47: Of course, the trick is making the black holes in the first place.

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

  • 11:02: The only black holes that we know for sure are buzzing around our galaxy are stellar remnant black holes.
  • 11:28: However, there's a theoretical type of black hole, so-called primordial black holes, which may have formed in the first instance after the Big Bang.

2016-07-20: The Future of Gravitational Waves

  • 00:14: ... LIGO, detected the gravitational waves from the merger of two black holes. ...
  • 00:43: These oscillations echoed the final 1/10 of a second of the end spiral and merger of a pair of black holes, each around 30 times the mass of the Sun.
  • 01:09: On December 26, LIGO again observed the merger of two different black holes.
  • 01:30: ... arm lengths that increased in both amplitude and frequency as the black holes approached before dying away again after the ...
  • 02:41: That's due to the fact that the smaller black holes took longer to coalesce as they became very close.
  • 03:51: If it were real, it would also be from merging black holes.
  • 04:14: We now have more confidence in our understanding of the space-time around black holes.
  • 04:20: We also now know that our estimates of the number of binary black holes in the universe and their masses are at least in the right ballpark.
  • 04:43: So far, we've only seen black holes merging.

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

  • 07:20: ... stellar bodies-- black holes, neutron stars, and brown dwarves-- occasionally pass in front of other ...
  • 09:03: But real lensing simulations show us what black holes should look like up close.

2016-06-01: Is Quantum Tunneling Faster than Light?

  • 10:15: Throw in some string theory and black holes and a really unique writing style and it's a very insightful Pop Sci book.

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

  • 10:06: The universe expands exponentially forever and eventually the stars die out, the black holes evaporate, and the universe undergoes heat death.

2016-04-06: We Are Star Stuff

  • 12:44: It's happening below the event horizon of black holes.

2016-03-30: Pulsar Starquakes Make Fast Radio Bursts? + Challenge Winners!

  • 01:11: ... colliding stellar remnants, supernovae, neutron stars collapsing into black holes, crazy stuff like ...

2016-02-24: Why the Big Bang Definitely Happened

  • 09:41: ... on just in time to catch the gravitational waves from the merger of black holes. ...

2016-02-11: LIGO's First Detection of Gravitational Waves!

  • 00:10: The Advanced LIGO Observatory has seen the spacetime ripples caused by black holes at the moment of merger.
  • 02:06: Now, LIGO is sensitive to pairs of stellar mass black holes and/or neutron stars.
  • 03:22: ... those few minutes, the merging black holes or neutron stars produce such strong ripples in the fabric of spacetime ...
  • 03:33: In the case of merging black holes, to five billion light years.
  • 03:44: It's expected that an observable merger of two black holes will happen only once every 10,000 years in any given galaxy.
  • 03:56: Advanced LIGO can feel the ripples produced by merging black holes through a volume of space equal to about 0.1% of the observable universe.
  • 04:31: ... of stretches and squeezes per second, that matches the rate at which the black holes were orbiting each other just before ...
  • 04:46: So we saw some black holes merge.
  • 05:42: These observations are going to tell us a ton about how black holes grow and about the physics of black holes themselves.
  • 06:13: ... is sensitive to gravitational waves at frequencies produced by merging black holes and neutron stars, as well as the formation of neutron stars and ...
  • 06:48: ... as well as the final dance of pairs of truly gigantic, supermassive black holes just before they merge in the cores of ...

2015-12-16: The Higgs Mechanism Explained

  • 09:05: ... stars near the core of a galaxy with merging super massive black holes should have temperatures raised by an observable amount by the ...

2015-12-09: How to Build a Black Hole

  • 00:00: [MUSIC PLAYING] Black holes are one of the strangest objects in our universe.
  • 00:13: [MUSIC PLAYING] In a previous episode, we discussed the true nature of black holes.
  • 00:37: And really, black holes were, at first, just a strange construction of general relativity.
  • 00:48: So are black holes real?
  • 00:51: Black holes are astrophysical realities that we have ample evidence for.
  • 10:43: ... get to what this means, for black holes and for the universe, in another episode of "Space Time." In a previous ...

2015-11-25: 100 Years of Relativity + Challenge Winners!

  • 01:24: On December 9, we'll delve deeper than ever into the weirdness of black holes, after which we'll start exploring the nature of matter and time.

2015-10-22: Have Gravitational Waves Been Discovered?!?

  • 03:16: ... most insane gravitational phenomena in the universe-- neutron stars or black holes in-spiraling just before merger, or gravitational catastrophes like ...
  • 04:42: ... if we could actually see g-waves, we'd be able to study black holes, neutron stars, even the extremely early universe in ways never before ...
  • 06:51: LIGO really just scratched the minimum sensitivity needed to spot merging neutron stars and black holes in relatively nearby galaxies.
  • 08:50: A little birdie told me that it's the signal of two black holes in-spiralling towards each other.

2015-09-30: What Happens At The Edge Of The Universe?

  • 02:51: Just as black holes have event horizons, so too do universes.
  • 09:06: MrLewooz asks if we can please stop throwing monkeys into black holes?

2015-09-23: Does Dark Matter BREAK Physics?

  • 02:37: And they're basically crunched down, compact, dead or failed stars, black holes, neutron stars, brown dwarfs, Macaulay Culkin, et cetera.
  • 07:36: ... next episode of "SpaceTime." Last time on "SpaceTime," we talked about black holes. ...
  • 07:48: ... and others asked whether a monkey falling through a black hole's event horizon should see the entire future history of the universe ...
  • 10:21: It never even happens in the distant observer's universe, either before or after the black hole's evaporation.

2015-08-19: Do Events Inside Black Holes Happen?

  • 00:00: [MUSIC PLAYING] I'm sure you've read, seen, and heard a lot about black holes.
  • 00:13: [THEME MUSIC] Today's episode, we'll only talk about black holes from the perspective of classical general relativity.
  • 00:32: Now, it's a lot harder to say what I want to say about black holes if I make this video self-contained.
  • 00:56: ... need you to put your preconceptions about black holes aside and for the next few minutes, become tabula rasa and let me tell ...
  • 01:54: ... close to the black hole-- see, eventually, the monkey will cross the black hole's edge without him noticing anything ...
  • 02:05: I see him weirdly slow down his progress until he's floating right outside the black hole's edge.
  • 02:20: So does another pony that's using powerful rockets to hover much closer to the black hole's edge.
  • 02:24: In fact, so would any observer, inertial or otherwise, who is always outside the black hole's edge.
  • 06:10: Misconception one, that black holes suck stuff in-- they don't do that.
  • 06:54: Misconception two-- black holes are black because not even light can escape their gravitational pull.
  • 07:50: Now, that's really freaky, but it's not the reason black holes are black.
  • 08:20: That means that to external observers, black holes are black because light that gets emitted just outside the horizon is redshifted into invisibility.
  • 08:37: ... three, that all black holes are super dense-- this kind of depends on what you mean by "density." If ...
  • 08:47: More massive black holes can have very low density.
  • 09:00: By the way, bigger black holes also have smaller tidal effects near their horizons.
  • 09:13: ... maybe that's not what you mean by "density." Maybe you mean that all black holes are infinitely dense because all the stuff that goes into the black hole ...
  • 10:18: ... black hole and I've always felt that whatever we're going to say a black hole's mass is the mass of, it should apply equally well to astrophysical black ...
  • 10:30: And in this circumstance, what are we supposed to assign the black hole's mass to?
  • 11:05: ... some of the philosophical subtleties associated with thinking about black holes as "things." Of course, I've only scratched the surface of black ...
  • 11:17: ... rotating black holes, charged black holes, black hole evaporation, what goes on around black ...

2015-04-08: Could You Fart Your Way to the Moon?

  • 06:52: The short answer is that black holes don't suck.

2015-04-01: Is the Moon in Majora’s Mask a Black Hole?

  • 01:38: And it gives us a chance to talk about miniature black holes, which I'm super pumped to have discovered lurking in a "Zelda" game.

2015-03-18: Can A Starfox Barrel Roll Work In Space?

  • 08:42: Likewise, people ask whether rogue planets or rogue black holes, streaking through the Milky Way, could come in and collide with Earth.
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