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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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