StarTalk Radio - Black Hole Bonanza: StarTalk Live! With Janna Levin and Jenny Greene

Episode Date: May 23, 2023

How do supermassive black holes form? Neil deGrasse Tyson and comedian Chuck Nice come to you live to learn about the history of black holes, what’s inside them, and new discoveries with cosmologist Janna Levin and astrophysicist Jenny Greene. NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free.Thanks to our Patrons Leigh Momii, Molly Jebsen, Gilbert Cruz, Robert Colonel, Oliver Orofino, and Stephen Coleman for supporting us this week.Photo Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)Derivative work including grading and crop: Julian Herzog, CC BY 4.0, via Wikimedia Commons Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. Philadelphia, we are back at the Keswick Theater. StarTalk Live! StarTalk Live! And now we're going to talk about black holes. And I have some expertise in black holes, but not enough to fill the length of this show. So we combed the landscape for my colleagues who spend their lives thinking about black holes.

We found one of them at Princeton University, not even that far up the street. As far as distances go, welcome to the stage, Jenny Green, professor of astrophysics. Jenny, there she goes. Thank you, guys. She's otherwise known as the black hole hunter. We're going to find out what that means. So you study supermassive black holes and how to find them

and where they're located in the universe. So you're a black hole hunter. universe. So you're a black hole hunter. And you also, she is faculty director of the Prison Teaching Initiative at Princeton. This is, Princeton has a program where the faculty go to the prison and teach. You teach algebra so that the prisoners can come out with some kind of a degree and reduce the recidivism. Yes. We salute you. Next, another black hole expert. One of our favorites.

She's a regular on StarTalk, really. And she is professor of physics and astronomy at Barnard and Columbia University. Jan Eleven! So, just so we understand the context here, we have Jan Eleven who approaches this problem of black holes as a physicist, and she's interested in cosmology, space-time continuum, and the like. Whereas, we otherwise are searching for actual black holes

in the actual universe, and so these are two sides of the same coin that we're going to explore this evening. So let's do this. I know you're all fans of science. You wouldn't be here otherwise. But let's make sure we're on the same page. Okay? So tell us what a black hole is.

Oh, that's a good thing. I was not pointing to you, Chuck. Chuck, my face. I didn't want to ask myself. Chuck, my face. I was just like, you know, I was just like, oh, when are they going to get to this part? You should always ask. Exactly.

Always ask. Yeah, so Jenny, tell us. Just give us the basics of a black hole. So a black hole is an object with so much mass in such a small space that not even light can escape its gravitational pull. So is it fair to say that the escape velocity, which is the speed necessary to leave an object forever, on Earth, I memorized all these, on Earth it's seven miles per second.

Wow. So Chuck, that old saying that your grandmother said, what goes up must come down. Right. Not true. Not true. My grandmother was dumb as hell. She just didn't have intro physics. This is true.

Right. So if you can throw faster than seven miles per second, it will leave Earth and never come back. Okay. And so the sun has an even higher escape velocity as you might expect. So a black hole, the escape velocity,

is it fair to say it's greater than the speed of light? Even going at the speed of light, you could not escape the gravitational pull of a black hole, the escape velocity, is it fair to say it's greater than the speed of light? Even going at the speed of light, you could not escape the gravitational pull of a black hole. So I'm on Earth. I toss something up and it comes back. If I take a beam of light on the black hole and turn on the flashlight, what happens to the beam of light? Oh, I love that one. Oh, that is great. You can actually get it to hang there forever. Light with hang time.

So the region that Jenny is talking about, beyond which not even light can escape, is known as the event horizon. And it's just a demarcation line. There's nothing there. Is that a poetic term for something that'll just kill you? The event horizon? Yes.

The event horizon. Exactly. It sounds innocent. You have to say it's smoky light. It sounds innocent. You have to say it's smoky light. But if you release a little pulse of light exactly at the event horizon, it will try to race outward at the speed of light.

But you can think of the event horizon as a region where space-time is falling inward like a waterfall at the speed of light. And so it just sits there. Oh, look at that. Oh, my God.. Oh, my God. You just described my marriage. Good thing this isn't going to be on TV or anything. Don't worry. She's here.

So, Janet, you wrote a book called The Black Hole Survival Guide, which is a little scary because you should not come close enough to a black hole to ever have to think about surviving it. Yeah. Is what I'm thinking. Yeah. Spoiler alert. It doesn't end well. Yeah. Okay. So you described, you said that black holes are nothing. Yeah. They are no thing. Yeah. They're not a thing. They're not a thing. They're not a thing. Why are we here? Why are we here? You can think of a black hole in some sense as a place. It's a place, it's a region in space, as you said, beyond which not even light can escape.

But that region, that event horizon, is left like an archaeological record on the space-time. The thing that formed the black hole, maybe it's a collapsing star, it can no more sit at the event horizon than it can race outward at the speed of light. So once it collapses under its own weight and it forms this region where everything goes dark, it is forced to continue to collapse

and leave behind an empty space with nothing in it. It's a prisoner of itself. So it's gravity created its own cage, in a sense. Yeah. And when the star forms it, it is forced to disappear as well down the black hole. The black hole, it's like dispenses with the star. So whatever made it is gone. So if you go up to that edge of the event horizon, it's as undramatic as stepping into the shadow of a tree. There's nothing there. So when people think of a black hole as a solid object, clearly it's not.

It is not. It's a region of space. Yes, it's a place. A region of space. Okay, so what's some background on this? Jenny, can you tell me, when did the black hole physics come online? Well, so one of the really cool things to me

is that when I learned about gravity in high school... We went to the same high school. Not at the same time, because I'm an old fart, but we went to the same high school. It was the Bronx High School of Science. We are both from the Bronx in the house today. Where I learned that gravity was a force of attraction because objects have mass, but light doesn't have mass. So there's this magical thing that it's actually bending in space and time, which light also moves through

space and time and so knows the effects of gravity. So the very first thing was we had to have this idea of general relativity. General relativity. So that's Albert Einstein, your favorite man. My favorite. Yeah. Yeah. You guys should know this, that there's an ongoing feud between these two. Whereas, of course, Neil's man is Newton.

Yeah, Isaac Newton is my man. And her man is Einstein. And often it's wonderful to get drunk and watch them fight about who is better. Isaac Newton discovered the laws of optics, the laws of gravity, and... He also stabbed himself in the eye with a stick to test out the rods and cones.

Yeah, just as an example. So there was that. Doesn't sound like a genius to me. But he did all of that and decided to invent integral and differential calculus. It's pretty impressive. Then he turned 26. Mic drop. All right, Jana, your response?

Well, Einstein said of himself, you know, when I was a student, I was no Einstein. So he was actually not a very good student. That's a really great line, by the way. That's really cool. All right. Let me clear up a couple. So we needed Einstein to advance these ideas, but Einstein did not even come up with the idea of a black hole. Actually, we can go farther back in time. I went to the late 1700s. Okay. There's a physicist named John Mitchell.

All right. John Mitchell. Forgotten. Long forgotten. He is, because until you said it, I still don't know who he is. Okay. John Mitchell wondered, once the speed of light had been established, he wondered, could a star be so massive that the light cannot escape

and that the star turns dark? And he called them dark stars. So this is the brilliant, even before Einstein, before he had the math tools to do this, he advanced this concept. And, oh, by the way, John Mitchell,

I have here in my notes, what I think is fascinating, all his work was forgotten. No one knew about this. He had to be rediscovered. Clearly nobody knew. Nobody here knows about him. Okay, okay. There's no picture of him.

And he was described by someone. This is fascinating. Go ahead. He was in England. Of having, he was black of complexion. Oh. Okay. So either he had bubonic plague or he was a black man. Okay. So either he had bubonic plague, or he was a black man.

Okay. Is bubonic plague black death? Is that right? That's the black death. That's the black death. That's why they called it that. Yeah. Because, you know, you actually turn black.

Yeah. Which is why it gets such a bad rap. Is that right? There's no picture of him. So we actually portrayed him in Cosmos, and we had a black actor portraying him. Just put him in there. Didn't even mention anything about it.

It was just, how fitting that a black man discovered the black hole. Okay. Behave yourself. All right. So why do you pick this up? When we think of black holes, we think of this voracious vacuum cleaner. That whichever direction, it just eats things up.

So is that accurate? Well, as we have discussed, things can't usually fall directly into a black hole. Okay. They have some energy, and so actually they tend to orbit. Swirl. Swirl around a black hole. And this stuff... That doesn't sound like a very good vacuum cleaner

if stuff's got to swirl first. But it does sound like an awesome toilet. Okay, so this whole thing that black holes suck, the way a vacuum cleaner, this is wrong. It's very overblown. If our sun right now were to turn into a black hole, With the mass that it currently has, With the mass that it currently has,

shrink it to a black hole. Some evil genius comes along, figures out how to shrink it to a black hole. It evil genius comes along, figures out how to shrink it to a black hole. It becomes six kilometers across. It's a really tiny little thing. Our orbit would be— This is America with six kilometers. I'll tell you what it is.

None of my damn business. It's about four miles across. I've lost miles a long time. You've lost a long time. Yeah, so it would fit inside New York City. Okay. Our orbit would be just fine. So we would no more be sucked into a black hole

than we are sucked into the sun. There would be very little detectable difference in terms of the Earth's orbit. We'd be perfectly fine. So this is a completely overblown hysteria. We would rapidly freeze to death. That would be bad. Okay, so don't say we'd be perfectly fine. So this is a completely overblown hysteria. We would rapidly freeze to death. That would be bad. Okay, so don't say we'll be fine.

Okay. The Earth would be fine. The Earth would just keep right on. As a planetary object. Right, as a planetary object. If the rock would persist in its orbit, we would be gone. All life on Earth. But there is life that thrives undersea

that absorbs energy from undersea vents, which is leftover heat from the formation of Earth. So depending on your age in the audience, I am of that age, we learned that from our biology textbooks that all life on Earth requires sunlight to survive. Take away the sunlight, we'd all die. That's before we had discovered this life form thriving at the bottom of the ocean, that are part of what we call extremophiles, life forms that do the backstroke.

Where the sun don't shine. Where the sun don't shine. Right. And so, just to be clear, yeah, surface life would rapidly die. Yeah. You got to get really close to a black hole is the point. Really, really close. This thing's only six kilometers across. You got to get within like 20 kilometers of it. I mean,

you're right on top of it. Which I have no intent of doing. Yeah. And don't do it to the sun either because that would also be bad. That would be bad. I'm going to ask that you guys stop speaking in metric terms. No, you could. NASA did a research study. They found that you can send astronauts to the sun, provided you visit at night. Just saying. Jana, why, if Einstein invented the framework to understand and even predict black holes,

A, why didn't he predict black holes? He did not, that's right. And when he learned about them, why was he in denial of them? Yeah, so he gets a letter from a friend who's an astronomer who has enlisted in the German infantry, he's a German infantry soldier during World War I,

and he's on the Russian front during the war. And the apocryphal story is that between calculating ballistic trajectories in the war, he's reading the proceeding of the Prussian Academy of Sciences. Is this Karl Schwarzschild? As you do, Karl Schwarzschild, in which Einstein has published his final description in mathematical terms. He nails it. General relativity, the theory of curved space-time. And Carl Schwarzschild does this little thought experiment. He says, imagine the entire mass.

While people are shooting at him. While people are shooting at him, yeah. He's, yeah, in the trenches hiding and calculating. And he does this beautiful thought experiment. He says, imagine you crush the entire mass of a star to a point. He doesn't ask how this is possible or how nature could do such an absurd thing. That's not really of interest to him initially. He just says, imagine it.

And then he asks of Einstein's equations to reveal to him what the nature of the curved space-time is as a result of that. And he writes down... So this is a thought experiment. It's a thought experiment. With the math. Very good. And he writes down the first description that has in it an event horizon,

a region beyond which not even light can escape. And it has all the descriptions of the space-time around a black hole. Einstein's very impressed by this. He couldn't believe it. Six months after Einstein publishes his theory. And he thinks this is terrific. He helps him get it published. But Einstein thinks, you know, nature's going to protect us from their formation.

After all, how are you possibly going to crush a star to a point? And so he doesn't think that they're going to be real. He thinks they're a mathematical— He thinks a new law of nature yet to be discovered is going to save his ass. Well, there are lots of laws that were there. Like, I can't crush this glass to a point. It's really hard. It resists pressure.

You know, matter has pressure. If you were a real housewife, you'd be able to do that. I mean, it was sensible. Only if it had a short name. I wouldn't do that over a glass of water. There was sensible reason to believe that matter would resist being crushed. Okay. So this is not sensible reason. I would call it a bias.

A bias that he had because he didn't think nature would do that. Okay. So now, when did we have our first evidence of a black hole? Well, we had our first evidence of black holes I believe in the 20s. Okay. So when did we first figure out that we had evidence of a black hole?

1970. So this is 50 years, 60 years after Einstein. Okay. So what's this famous bet between Stephen Hawking and not an Einstein? What was it? And Kip Thorne. Remind us who Kip Thorne is. Kip Thorne is a very brilliant

relativist. A lot of his work as a scientist was in the area of curved spacetime, big bang black holes, wormholes, that sort of thing. He won the Nobel Prize recently, fairly recently, in the past few years for his work. 2020. Yeah, in discovering or theorizing about the collision of two black holes ringing space time like a drum. And when it was eventually observed, a project that he was involved in for more than 50 years, he received the Nobel Prize along with his collaborators.

And he's also wrote the treatment for Interstellar. The movie. He was a slacker. Not only wrote the treatment, he was listed as executive producer of the series. Do you remember? Did you guys see Interstellar?

Okay. Wait, who has not seen Interstellar? Okay, security. Notice they didn't clap. Notice they didn't clap. No, they didn't clap. The people who saw it were like, yeah! Like, who has not seen it?

I'm okay. By the way, those who remember it, there's a robot in it that had these sort of funky rectangular legs. Yeah. Do you remember the name of that robot? No? Well, there were several, but the lead one was called Kip. It was called Kip. The robot was Kip.

After Kip Thorne. Kip Thorne. That's how you get your situation in the situation. I remember that because he told him to turn down the humor, and I was like, I'm done with this movie. All right. So there was a bet between Stephen Hawking and Kip Thorne about this, whether or not we actually had the data justified for a black hole.

So what was the first black hole? Well, I know it was a stellar mass black hole, so 10-ish suns with a star friend, and the black hole is slowly eating material from the star. So the black hole is flaying the star. Okay. So they should call them vampire holes. For real. Okay. So they should call them vampire holes. For real.

Yeah. So I remembered because this swirling material that you began describing earlier can get very hot and start radiating in a form of light that you get

when you have very hot gas, such as X-rays. And so when we first had X-ray telescopes, we started discovering these sources of X-rays that didn't, there was nothing else obvious happening in that region of space. And one of them was a strong X-ray source in the constellation Cygnus. And so it was sensibly called Cygnus X-1. So I remember, I was alive, because that's how old I am.

When that was discovered, we were very excited. We read all about it. Is that still to this day a confirmed black hole? Yeah, yeah. Look at me like, yeah, okay, sorry. But it is worth pointing out that that doesn't mean we could see the black hole. Like you couldn't resolve the black hole. You were deducing that the object

that was emitting this incredible high energy, you could tell had a certain amount of mass and was very, very small. And you deduce from that, that it's a black hole, but all you could see were the x-rays. So you couldn't see the black hole itself. And I think this surprised people to learn that we really didn't see a black hole

for many decades. Let me just understand this. And I'm serious when I'm asking this. Are you saying that the x-rays were emanating from the black hole? Is that the black hole is spewing out x-rays? It's emanating from around the black hole. What's that? From around the black hole.

It's the stuff that's trying to fall into the black hole. Don't you learn anything? They said nothing comes out of a black hole. And that's my point. So how are you seeing something when nothing can escape it? How are you seeing anything around it? That's what I want to know. It's because this reputation of black holes sucking up everything is overblown.

Things can live very close to the event horizon of a black hole, be very hot, and you do a lot of work on this. And what's happening in those disks? Yeah. The stuff is swirling around. It wants to get into the black hole, but it has some energy, right? Okay. And so it can't just fall right in. So what nature does is it forms...

It has orbital energy. It has orbital energy. That's right. It forms these disks, accretion disks. Okay. And what happens in the disk is that the gas cozies up with itself. It gets really nice and close.

And it gets hot. It gets hot. It rubs against itself. It gets hot. Okay. And this is super exciting for astronomers because how astronomers study the universe is by gathering light right and so without that stuff near the black hole we wouldn't have found those so we're not we're not seeing anything from the black hole itself all we're seeing is what's happening around the black hole. Yes. And that excited material that gets all like,

hey, man, we're about to go to a black hole, man. We're about to die. It's crazy. And then it gets hot and it gets excited. And then we see that as light. And that's how we know. Light of high energy wavelength. High energy wavelength.

Yes. And so it gets to... What the hell is wrong with you people? That is amazing. Okay. I just learned something. I don't know about you,? That is amazing. Okay. Wait, wait. So... I just learned something. I don't know about you, but that is amazing.

Okay, wait. That is amazing! So what's raising... We see nothing! And we know everything from seeing nothing! All right. Okay. Chuck just blew a gasket.

We got to bring him... We got to repair Chuck. This is why I love doing this show. I'm sorry. This is why I do it. That's amazing. Go ahead. I'm sorry.

Okay, Chuck will be in for repairs this weekend. So this friction is the gas spiraling down, losing that energy that it had, and it's got to end up slow enough to drop in. It's circling the drain. The drain. Yeah. The drain. Yeah. The toilet bowl.

So this friction, you've done this in cold weather, but you can just do it now. Rub your hands. It doesn't take much rubbing to feel the temperature of your hands go up. Just do it. You know the result, but just try it. First clap them, and then do that.

Okay, so... And then go heal somebody. First you clap, then do that. Okay, so... And then go heal somebody. First he claps, then he runs. Yeah. And now you're healed. I told you Chuck needs repairs. All right, so was there a bet and who won it? Who bet on what?

Oh, so... Stephen Hawking and Kip Thorne. Kip is the loveliest guy, and he's a straight shooter. He's going to vote for the black hole. And Stephen was a bit of a trickster and had this kind of inimical quality to him. Stephen, she's on first name basis with Stephen Hawking. Oh, that's so obnoxious.

I'm sorry. Hawking was a bit of a trickster, and so he bet against black holes, even though so much of his life had been devoted to understanding them. I think he also suspected that they were observing a black hole, but he just wanted to, you know,

he wanted to bet the, I don't know, be the opposition, be the antagonist, be the devil's advocate. So yes, he bet against Kip, but he did capitulate pretty early on. And I think the story is he broke into Kip's office at Caltech or some such. Wait, Stephen Hawking did this? Yeah.

What point in his life was this? That's a detail left out of the story. I'm just trying to. We'll let that one go. I'm just saying. We'll let that one go. Okay'm just saying. We'll let that one go. Okay. So he rappelled down the building.

I mean, I would believe it because I would leave it up to Stephen Hawking to figure out a way to rappel down a building, you know. Yeah, to break into Kip's office, yeah. Okay. And so, Sam, what happened when he broke into the office? Well, I think he left him a note conceding okay conceding the bet okay okay so that's odd for him to be anti-black hole because because of his intellect we know so much about black holes so one of them is like black holes are not forever so what do black holes do when left to their own devices well okay so this is a very subtle issue because Chuck already raised it.

The black hole lets nothing from the inside out again. But Hawking figured out this very clever way. The black hole could kind of steal energy from empty space. And I don't think you want me to get into this whole thing because this is a whole big thing. But there's this possibility that empty space sort of, you know, has this frothing quantum foam that sort of rots. Oh, that has got into the quantum.

And it is only when you introduce the quantum that this happens. Only then. And he figured out a way that the black hole could steal a little from the empty space. What you're saying is Newton gravity, Einstein gravity alone doesn't get you this result. Does not. He has to bring in quantum physics. Absolutely. Which is the physics of the small to describe something that's going on in the physics of the large.

And for you children out there, sometimes when Newton gravity really loves Einstein gravity, they get together and they make a quantum so so it's is this when we hear that black holes evaporate so what happens is the black hole ultimately evaporates it actually uh gets less massive and it exposes something in the vacuum that has to radiate away so it doesn't come from inside the black hole but it's in tandem with this quantum process. But what it looks like from afar is it looks like the black hole is evaporating. It is emitting particles at a hot temperature

and it is getting smaller in the process. When I first learned this, you know what freaked me out? And maybe it'll blow another gasket for Chuck. When I first learned this, it was like, wait a minute. It is spontaneously creating particles out of the gravitational field outside of the event horizon, outside of the event horizon loses mass to stuff that's happening outside the event horizon. Yeah.

All right, I gotta go smoke some weed. I'll be back. That's exactly right. It essentially absorbs what we would consider to be a negative energy particle in favor of emitting a positive energy particle you could say something like negative energies don't exist but because of the relativity of space and time inside the black hole you don't think it's a negative energy you think it's a negative momentum and so it's completely consistent with the laws of physics. I'm leaving with Chuck, right? No, that is dope.

What you just described is what Harry Potter would call magic. So where did the term black hole come from? Oh, so that's a great story because Schwarzschild didn't call it a black hole. Einstein didn't call it a black hole. It was 1967, I believe, and the great John Wheeler, who was the kind of granddaddy of all of relativity in America.

And a student of Einstein. Yeah, a student of Einstein's, and he trained Kip Thorne and Richard Feynman and all of these great people. He was on stage near Columbia, like above Tom's Diner, you know, from Seinfeld. Swear. And giving a lecture. It wasn't Tom's Diner, I don't believe,

in the 1967. And he kept saying the end state of catastrophic gravitational collapse over and over again. And apparently from the back row, somebody shouted, how about black hole? And he just took it and foisted it on all of us. And one day he wrote something to the effect, like the Cheshire Cat, the star fades from view. One leaves behind only its smile. The other leaves behind only the black hole. I butchered that a little bit, but it's something like that. And with that usage, it was on us. I just feel bad for the guy who yelled it out.

Because nobody will never know who he is. And he came up with the actual name jenny you focus on super massive black holes and i you know we we bandy about the word super so often that it almost loses meaning i'd like you to sort of give it strength and presence once again. So what's a supermassive black hole? What's an ordinary black hole? Is there a mini black hole? What is the mass range and where do we find these beasts? Yeah. So usually when we say supermassive, we're thinking about million suns. That's our own black hole at the center of the Milky Way. So we say million suns, you mean take the mass of a million of our suns and cram it into one object to make a black hole.

A million. A million. And by the way, if the sun were hollow, you could pour a million Earths into it. So a million, a million. Million, million. A million, million is what a supermassive black hole is. Correct.

Okay. The low end. They can be a trillion. Yeah. So the friend we talked about earlier where we saw the base of the jet, M87, we know we've seen a picture of its event horizon. That's a billion. So when I was a kid, we also had the Sig X-1s of the world.

These are like the mass of the sun but a bit bigger, so maybe 10 suns. Now LIGO, we've seen black holes, or we've heard black holes emerging. LIGO is the abbreviation of the telescope, the gravity telescope that Kip Thorne pioneered, Laser Interferomity Gravitational Wave Observatory. Okay, so go on. And where's the wave?

See, every time y'all say that i'm like there's no w but never mind astronomers love their acronyms don't let real words get in the way go ahead so so for for all time it was 10 suns and then a million suns. And one of the amazing things for me as an astronomer that LIGO has taught us is that it's actually these stellar mass black holes go all the way up to 100 suns at least. But that still leaves a big space between 100 and 100,000 or a million, and we just have no idea. We just don't know. Okay, so we don't even know

what mechanism could create such an object. Well, so with the 10-ish sun black holes, we actually... That's just a dead, fat star. That is the death of a star. Yes. We got that. And then these things up to 100,

they seem to be probably the mergers of those. Okay. Right? Well, we see them merging. That's... Chuck, you see what she did there? It's Well, we see them merging. That's, that, Chuck, you see what she did there? It's like, we don't even know how to make those,

so let's add the others together and that's how you get there. But LIGO has detected 30 and 30 or 60 and 30 merging to the 100 range. I get that, but we don't know how to make those, so you just staple together

the ones that are 10 solar masks. Is that what you're doing? Well, not with the super masks. Not with a staple gun. You guys are witnessing your first science fight. Like nerd fight. All right. So I just admit, we don't know what could make a 30 to 100 solar mask black hole.

No, no. 30 to 100, you can't. But a million, we don't know. A million, we have no idea. But you haven't detected a million yet. Yeah, like the supermasks at the center of our galaxy, Our own Milky Way is a million. Four million.

Four million. Four million. Three point, yes. Four million, okay. When we come back, we will resurrect this argument about how massive the black holes are and what in the universe is making this.

Not that size matters. On StarTalk. Hi, I'm Chris Cohen from Haworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson. We're back for segment two

with the Keswick Theater of Philadelphia. All right. Star Talk Live. I got with me Jan 11, black hole extraordinaire expert, and Jenny Green, a professor at Princeton University. All right.

So in this segment, we want to spend a little more time on detecting the undetectable. And of course, you know, our friend, the one with black complexion, gave us, gave

a first indication, John Mitchell, of how you might detect it. And that was, if a star is black, dark. It will get pulled over by the star police. In a second. Do you know why I stopped you? I was not doing faster than the speed of light.

That would be impossible. But we clocked you at 1.5, the speed of light. The speed of light. It's not just a good idea. It's the law. Yeah. I don't even remember where I was here. Oh, Mitchell, thank you.

So he's supposed, because by then we knew that there were stars that were double. There were double stars. More than half the stars you see in the night sky come in at least pairs, and in some cases tripled, and even entire clusters. So the isolated star is not even all that common. And the only, I would say, single correct science out of all 30 Star Wars movies was in the first Star Wars 1,

which I think they call Star Wars Part 4, where they show Luke was at the sand planet and he comes out and there's a double sunset on the horizon. And they said, somebody finally did this. And so more power to the people who thought that up. That's the only thing they got right. That's the only thing they got right in the entire series. Just thought I'd put that out there.

If you want to fight, meet me outside. We'll, after school. So what he said, so if you just see a star doing loop-de-loops, and you don't otherwise see anything there, then something dark has gravity and is tugging on it. So Jenny, pick us up from there. All right, now we left off when we began with this jets and all this stuff, and Chuck blew a gasket hearing that we still

can't see black holes. We got an hour and a half show on black holes, and we still can't see them. So what are the clever ways that ingenious astrophysicists have come up with to detect them? Right. So this is why I'm on Team Newton, because almost all the ways that we find black holes actually don't even need general relativity. It's just Newton's laws, right?

Like I said, Jen. I'm going to be the one waiting for you outside. Right, so the star friend of Sig X-1, we can watch it going around Sig X-1 and we can figure out there must be a really dense object there. Just like planets going around the sun, we can figure out the mass of the black hole. And in fact, we can do the same for the black hole at the center of our own galaxy, Sag A star. So there's a black hole.

So the Milky Way has its own black hole. We have our own supermassive black hole. We have lots and lots of stellar mass black holes. And we agreed that's four million times. Four million suns. And the thing about black holes is that they're spatially small. So that's less than 20 times the width of the sun, but it's four million times the mass.

So picture the sun on the sky. You know, don't stare at the sun, but like picture the sun in the sky. Imagine just, you know, 20 times across. And this thing is. And then cram a million suns. Four million. Four million suns into that space.

Yeah. And then push it 26,000 light years away. And it's like a tiny, teeny little thing on the sky. So it's about as big on the sky as people liken it to a piece of food on the moon. So it's really tiny. And that's why black holes are so challenging. Because despite their heft, they're spatially small.

So, small and hefty. All right. So we have this range. There are many jokes I'm not doing right now. All right. So I'm of the age where black holes in the centers of galaxies was a new idea we found them in one galaxy and then another random other galaxy and as we do in my field if you find it in this galaxy in that then all galaxies must have it that was the driving presumption and sure enough

when hubble came online it had good views down in the centers of galaxies and bada-bing. We have yet to find a galaxy that does not have a supermassive black hole. Is that correct? I guess not, okay? That's not correct. Meet me outside. We'll settle this in the parking lot.

That was great. Big galaxies. Big galaxies. Big galaxies like our Milky Way or M87. Yes. So far as we know, they all are most. Isn't that all I was saying? Wait, here's the real question. Have we found galaxies where there are not supermassive black holes?

Big galaxies. Big galaxies. Yes, yes. Red-blooded American galaxies. No. Like the kind of galaxy you would put in the back of a cosmic pickup truck. Yeah, a pickup truck with a gun rack. That's right.

We got one of those? We have smaller galaxies that don't have black holes. Is it possible they were? We have not yet asked for their passport, so we can try that. All right, all right. Okay, I got you. All right, so now this galaxy, one of the most massive galaxies in our catalogs, is in the Virgo cluster, super cluster of galaxies,

because galaxies cluster the way stars cluster. They're very cliquish. That's the universe just doing its thing with gravity. So we have the Virgo super cluster. It has thousands of galaxies. The most massive galaxy in that is in the Messier catalog. Messier was a French astronomer in the 1700s. And an awesome hockey player.

He wanted to make a catalog of fuzzy objects in the night sky so that you don't confuse them for comets that you might be trying to discover. So it's called the Messier catalog. And this is this, it's really the catalog of not comets. But it turned out to be a catalog of the most famous fuzzy objects in the night sky, including Messier 87, which is this supermassive galaxy.

It's far enough away, it's just a smudge of light, but it's got trillions of stars. So we recently, the astronomical community, recently published a photograph of that black hole. Tell me about it. We can actually see light swirling around the event horizon because astronomers are incredible at working together to build these pictures and as janna said it's a piece of fruit on the moon

in terms of how big it is in the sky so so i've heard there's something called the event horizon telescope so that lets you think there's like one telescope sitting somewhere looking for black holes. But what is it actually? So it's a network of telescopes. And what's important for getting a tiny, tiny picture is that you put your telescopes as far apart as possible so that you can get this really, really high angular resolution. So you're not getting different sets of data in principle.

You're getting one coherent set of data as though the telescope were as wide as the diameter of the Earth. Basically. Although you have to work really hard to make the data coherent. A bunch of cameras taking the same picture. And you get the resolution of something as wide as Earth, as though your telescope were that size. As though your telescope were that size. As though your telescope were that size.

But in fact, you have all of these different telescopes you're coordinating. And you have to combine them. They each have detectors that somebody had to build and commission. I looked at a list of the collaborators, and I'm like, what? Because in it, I'm like, I cannot believe they let george on here look there are countries that historically and even today were at war with one another yet the scientists are collaborating can you comment on that that deserves applause i don't know who wanted to applaud yeah somebody started applauding but yes that deserves applause because quite frankly only these guys can absolutely hate each other but love science so much that they will continue to work together

and that should be a model for the rest of us to follow right right in the geopolitics of the world. It should be. So the Nobel Prize in Physics, which includes prizes for astronomy, can only be awarded to three people or less. And there has been sort of a discussion, I don't know how seriously it was taken, that the Nobel Peace Prize should be given to major scientific collaborations because they are working both across things

like the Large Hadron Collider, the James Webb Space Telescope, the Event Horizon Telescope. These are examples of what human beings can do if we put our minds to it. International. As a model for geopolitics. Yeah. Yeah, interesting. So you would simply open up the Peace Prize to not only the usual things that might earn it, but then the collaborations that transcend governments. That are demonstrations of it.

Okay. We got the message. All right. So I want to get back to this jet we first started talking about. So we get this disc, accretion disc, which is officially called Around a Black Hole. By the way, when I think of accretion disc, I kind of think of the middle accretion disc around my equator.

The middle-aged man. Why? Are you eating a Cretan? No. So, okay, we got through that, and we rubbed our hands, and we figured this out. But now we have jets. So what's, tell me about jets.

I will tell you this about jets. I like that she leaned in on that one. Yeah. Grabbed a drink. And before you do, let me tell you about jets. When you're a jet, you're a jet all the way. From your

first cigarette to your last dying day. Okay, sorry. Go ahead. Alright, so tell me about the jet. So I have these accretion discs. How do we get a jet out of them? Well, I guess the exciting and beautiful thing is we don't really know. Oh, okay. It's got something to do with the black hole the black hole's got a lot of energy there

are these particles that are accelerated we think we're getting the energy from the black hole to power the jet yeah i'll tell you what when i go to meetings about black holes and accretion the jet session is when i leave to go see the European town that I'm visiting. Whoa! Whoa! That was a big confession. That was like a public

confession. That was the most elegant diss I've ever heard. That was called what? Dad! For 30 years, we've been talking about how to accelerate jets, and we just don't know. But I do think that the irony is that what the black hole is basically doing is it's acting kind of like an electromagnetic battery. So there are these magnetic fields that are threaded through the accretion disks that the black hole can't do on its own. It needs that stuff around

it. And then the churning of the space time due to the black hole actually basically creates a gigantic battery, which starts to power these jets. So these jets are electromagnetically powered. And so black holes go from being the darkest phenomena conceivable, as we discussed in the beginning, to the largest sources of electromagnetic power in the universe that we can see at the edge of the universe. So is this an overload of this electromagnetic battery that it just can't contain all the energy that is being generated inside the secretion disk and all of a sudden it just like accelerates the particles, they get excited and they're just like,

I'm out of here! Well, literally, it's churning up the magnetic fields, and then the magnetic fields are literally like wires in a circuit, and the charges are currents. Following them out like currents. They're currents flying out on the circuit. This is why science is awesome! That's the second thing I learned tonight.

That's amazing. It is amazing. Chuck just blew a third gasket on that. So, Jenny, tell me about your work with the James Webb Space Telescope. We've all been enchanted and stupefied by the beauty and majesty and its access to previously untouchable parts of the universe. So, it's really life-changing. I would say it's like a once-in-a-career experience it's been for me

to see the James Webb data. Okay, cool. All right. So as we said, we said there are stellar-ish mass black holes and there are supermassive black holes, and then we don't know how to make the supermassive black holes, but we figure they must have started out smaller, somewhere in this intermediate mass black hole regime where we can't find any.

But for my whole career, I've been saying, if we can find these intermediate mass black holes, we can understand how supermassive black holes form. And I've been saying, we're never going to find them back near the Big Bang early in the universe because we just don't have the telescopes. So let's look for them nearby. And that's been most of my career. And now all of a sudden, we put this, you know, six-meter gold-plated thing into space, and we are, honest to God, we're finding the baby black holes.

You're finding baby black holes? Oh, my God. Are they cute? They are so cute. Are they like Grogu? Are they like little baby Yodas? I don't know how you would feel if you saw the spectra, but when I see it, I'm like, oh. So you're reacting not to a photo of the black hole. You're reacting to a spectrum of the energy emitted in the vicinity of the black hole. Right, it's the secretion disk again. And you just are touched.

It warms your... It looks like the data that... I've got to tell you, it kind of sounds like you're being catfished. I really, really hope not. Yeah, so these black holes, you say they're baby black holes that implies they're young but are they actually young or are they just small oh well so all the black holes are young because we're seeing them you know just a few million years after the big bang right because james

webb okay so everything is that age everything Everything is young. Yes, they're all adolescents back then. Oh, that's kind of dope. Okay. As we see farther out in space, we look farther back in time. Right. So we see things not as they are, but as they once were. Oh, that sounds so romantic.

Now I feel like looking back at my life. Alright, so this has stoked your career. That sounds so romantic. Now I feel like looking back at my life. All right. So this has stoked your career. Yeah. Wow. Okay. So you're still studying them. Is there anything you can share with us about it?

Anything new and exciting? What is Pandora's Cluster? I read about this. Yeah. So you already covered galaxy clusters. Yes. Right. Well, this is a galaxy cluster.

It's got a thousand galaxies in it or something, and that means it sits in a really big dark matter halo. And we've already talked about how space-time can bend light, right? Wait, pause. What's a dark matter? So dark matter is a form of matter that does not interact with light. It's that simple. Okay, wrong answer. What is dark matter? So dark matter is a form of matter that does not interact with light. It's that simple. Okay, wrong answer. What is dark matter? Oh, we don't know. We walked into that one.

It's not only that we don't know, we have no freaking idea. I would say we have a little bit of an idea because we do know that it acts like matter and we do know it doesn't interact with light. And we know that there are things like neutrinos which exist which are technically dark matter no question and by the way probably shouldn't be called dark it should be called invisible like if i had a handful of it it's not that it would be dark it would literally be invisible so it doesn't scatter light it doesn't absorb light light goes right through it so so we don't know what this dark matter that makes up the 20-some percent of the energy that's in the universe.

But you know it has gravity. So you should call it invisible gravity. Well, we know it acts like matter in its pressure, energy, you know, its equation of state of matter. Looks like regular matter in that sense. Okay. So it's implicated as particles. All right. Whereas dark energy it's implicated as particles. All right.

Whereas dark energy is not particulate, presumably. And also, we don't know what that is either. And also, it's not dark. It's also invisible. This sounds like a case for a science Angela Lansbury. Okay. So dark matter, halo. So you've got this cluster in the middle of a dark matter, halo.

So we have James Webb already an incredibly powerful telescope. Yes. But we use the power of gravitational lensing to make it even more powerful. So because this invisible mass is sitting between us and the very early universe, the galaxies way back, you know, 500 million years after the universe started. So just much farther back in time than the cluster you're studying. That's right.

The cluster is basically right here. Okay. But we're using it for its mass. And it is like a lens. It's lensing these galaxies. And so we can see even smaller and even further back in time because we're using the power of gravitational lensing. We are exploiting the magnifying effects of Einstein's

general relativity in the distortion in the fabric of space and time to see where even that telescope, the James Webb, would not have seen without that cluster. Is that correct? Correct. So my colleague, Ivo Labe, who runs this survey, so remember James Webb was built to have infrared vision because as the universe expands, the light gets stretched out. And so by the time it reaches our telescope, it's redder than when it left its galaxy.

So we need these infrared goggles. Just to be clear, because I don't know that everyone fully appreciates that design feature of the James Webb Space Telescope. Because I remember, I'm old enough to remember when we were speccing what it should do for us, like no other telescope before it. And we said, we want to see galaxies being born.

Well, what kind of light are they emitting? Well, they're emitting, like, ultraviolet. Well, how are we going to see it today? Well, over that time, it's going to become infrared. So we built a telescope to detect the infrared that used to be ultraviolet at the time the galaxies were emitted. Thank God we don't have that technology for actual children. So it's an extraordinary achievement in our understanding of the universe and the power of our technologies to make that happen. Just a shout out to the engineers that empower what we do as scientists. Yes. Okay. So continue, please.

So my colleague, Ivo, he's looking for baby galaxies. We have this lens, this magnification to help us out. And what he finds are things that are way redder than any galaxies we expect to see. And what he thinks he's found are basically universe-breaking galaxies. They seem to be way bigger, like the size of the Milky Way already. And no one thinks there was enough time to make those galaxies yet. How did you make all of those stars so quickly? Because it takes a certain amount of time for a galaxy to form. And we don't have that kind of time.

It's too close to the actual singularity that we're talking about to begin with, so there's an incongruency in the time itself. So these galaxies shouldn't exist in our current understanding of the early universe. Yeah, so it turns out... So what did you do about that? Everybody knew at the time. Well,

the other way... Everybody knew. Now y'all know how I feel all the time. Okay. What's the other way you can make this very red thing that seems very powerful? It seems like it's powered by lots and lots of stars, but as we've already established... Oh, we have objects

in the universe called quasars correct which can can generate intense energy in its regular galaxy but the center of it can generate intense energy and we think some of that intensity is because it's aiming stuff at us is Is this where you guys are landing? Well, it's probably just a regular accretion disk, but it can make a lot more light than stars. Because it hasn't collapsed into a black hole. There's a black hole in the middle. In the middle.

And it's our hands rubbing together that accretion disk. So we think, in fact, instead of universe-breaking galaxies, he actually found a bunch of accreting black holes early on okay all right so all right wait y'all y'all get this that was some deep stuff man so so look no because i'm serious that i just got what you're saying is like basically you look back you thought you found this galaxy galaxy that was old enough to be a galaxy, but it's too close to the singularity to actually be a galaxy. But really what you found were a bunch of black holes

just hanging out like, yo, what you up to, man? I know. What's up, man? And so it's all these black holes that have gathered, and because we can't see them, what we're really seeing is all the energy that all these black holes are giving off. So it's not these old, super old galaxies. It's a bunch of young-ass black holes. Young-ass black holes.

And that's what it is. You got it. Science! Right. Okay. Okay. But Chuck, I want to take a slightly different view of this. Okay.

Jenny, James Webb discovers five galaxies that don't fit our understanding of the universe. So rather than allow our understanding of the universe to break, you invented some explanation for it so we can continue to think that we understand the early universe. Oh, his has killed everything I see. Isn't that what just happened here?

Well, but the thing is... Well, but, well, but. Okay, what? We got spectra. Oh, okay. Yeah. All right, when we come back, we are going to dive into the belly of the beast

and find out what the laws of physics tell us of what could be going on inside a black hole and whether any of that physics and understanding of the space-time continuum would even allow wormholes. When StarTalk Live at the Keswick continues. And now,

the third and final segment of StarTalk Live at the Keswick Theater. Let's do this. I am with my comedic co-host, Chuck Nice. All right, and we've got Jenny Green from Princeton. And we've got Jana Levin from Barnard and Columbia. Two of the three of them are experts in black holes. In this segment, we're going to talk about what's inside a black hole.

And is there time travel? Is that possible? Is just let's go places that telescopes have never been. Let's go ahead and do that. So, Janet, in your recent book, The Black Hole Survival Guide, I know, right? What are you planning? You know what I'm saying? Clearly, you build a spaceship.

You go somewhere. I'm not going to do the spoiler alert, but yeah. It doesn't end well, as we yeah. But you take the reader. It doesn't end well, as we've described. You take the reader on a journey towards a black hole. You cross the event horizon and take it into the depths of oblivion. And she's laughing. This is sinister here.

It's a little sinister. I'm a little worried about this right here. Right here. I'm feeling a little punchy. Right here. All right. So tell us about that. Well, we were discussing how if you cross a big enough black hole,

which most black holes are big enough for human beings, that when you cross it, it's actually quite undramatic. You really don't notice much happening. There's literally a principle called no drama, which is the idea that there shouldn't be anything special happening at the event horizon. So if you did not know everything about black holes and you simply saw this shadow cast on the sky,

like maybe there's a whole bright galaxy behind it and you can just see the shadow of the black hole and you went and you approached, you would enter the event horizon and maybe not even know you had done so. But then terrible things begin to happen. This sounds very much like Thanksgiving dinner. So, Janna, your book is mistitled because you call it the survival guide,

but it's really your recipe for death. Yeah, it is definitely ill-advised to actually cross the event horizon because it is a guaranteed death experience. Because you're not coming back. You're definitely not coming back. And we all love, we all love... Okay, here's a subtle way you might come back. Okay.

Oh, there's a way back. Okay, there's a tiny way back. So we talked about Hawking. And people have been arguing about this whole Hawking thing for a long time. So if black holes evaporate, eventually the black hole disappears. And this event horizon, which is like this curtain blocking everything that happens inside the black hole, separating it forever from us outside. You're in, you're never coming out. No information comes out. When the black hole evaporates, it's like the curtain's been yanked up. And where did all that stuff go? And so this has been a really hotly debated topic

for a long time. And you might say, it just disappeared. But physics doesn't allow that sort of thing. That breaks physics. And so people have been arguing, well, maybe the information actually does come out of the black hole. Information that was previously lost by having fallen into it. And the information could be that it's Neil deGrasse Tyson and it's all your quantum numbers and it's all the way you're organized. It's in your entire life history.

And if you fell into the black hole, we would never ever be able to get that information out except through this really subtle, magical thing Hawking discovered of the radiation. So maybe if I wait outside the black hole long enough

and I collect every detail of that information that came out, I could reconstruct you from that quantum information. It's like every Star Trek transporter episode. Yeah. Okay. All right. So tell me about if you actually greet the singularity at the bottom of the black hole, then you should at some point have become spaghettified.

Yeah. Well, you're the king of the spaghettification story. I mean, you tell it better than anybody. I mean, I'm not going to Neil deGrasse Tyson you. Is it my turn now? Yeah, it's your turn. Should I give my account of spaghettification? All right.

You guys seated? Okay. So what happens is, as I stand here on Earth, you don't feel this, but you can calculate that because my feet are closer to the center of gravity of the Earth than my head is, that Earth is actually pulling on my feet more strongly than it is at the top than my head is, that earth is actually pulling on my feet more strongly

than it is at the top of my head, because my feet are closer. You don't feel that difference. You can calculate it is insignificant at all. The molecular structure of my body resists that on a level that you don't even notice. Well, that's because I'm here six feet two, and the radius of the earth is 4,000 miles. All right, but now watch. We get one of Jana's small black holes, and I'm falling towards the singularity. Now my height becomes significant relative to the distance that I have left to fall. Relative to the distance that I have left to fall.

So the gravity at my feet gets stronger and stronger and stronger relative to the gravity at my head. And I begin to stretch. Now, initially, a stretch, who doesn't like a good stretch? Oh, so refreshing. And then until you realize this is not stopping. And these are called tidal forces. Yes. It's the stretching force of gravity's difference from one side of you to the other.

It's when the black hole gets medieval on your ass. I hadn't thought of it that way. That is totally one of those racks, you know, where they try to. Yeah, the medieval times always trying to rip you apart somehow. Drawn and quarters. Okay. So you're falling in. You feel the stretching. And then you realize this is not stopping and it's no longer comfortable.

And it reaches a point where the tidal forces exceed the molecular binding forces of your flesh. And you split. You split, likely at the base of your spine. Now you are two parts falling towards the singularity. And they feel the tidal force of the black hole. And so those two parts stretch. You will probably still be alive at this point because you have important organs

but not vital organs below your waist. Right. So it's like when you see that zebra getting eaten by the lions and it's looking down at them like, I can't believe y'all eating me, man. That's messed up, man. I can't believe y'all are eating me.

So you bifurcate first into two parts, then your bottom half and upper half bifurcate again. And that next one will probably sever you at your neck. And you might survive that a little bit. Experiments during the French Revolution where they're just chopping heads. You might as well participate in a science experiment while they're doing this. That the eyes connect directly to the brain, don't require the rest of your body. Right?

You saw the whole thing coming. Okay. Do all French people smoke? Of course thing coming. Okay. Do all French people smoke? Of course we do. Okay. Especially when we are at the beheading. So you go from two to four to eight to 16, 32, and you bifurcate all the way down

until even the molecules that previously held you together, the tidal forces end up splitting those. And you become this stream of atoms descending to this cosmic abyss. And that's not even the worst part. As you're falling in, you are being funneled down to a narrower and narrower volume of space-time. So you're not only getting stretched head to toe, you're being extruded through the fabric of space-time like toothpaste through a tube. When you step back and look at this, basically, there's no other way to describe it, you have been spaghettified.

And the whole time that that is happening, you are hearing, when the moon hits your eye all right so so suppose you survive your trip through the event horizon okay what's this stuff you can see the back of your head what what is that oh well that's that's actually optical effects yeah that can that can even happen just outside the event horizon actually there's a point where if you were shining light on your face and the light was reflected off,

or actually shining light in the back of your head, it was reflected off the back of your head, it could travel all the way around the black hole and you could see it. Because even the light gets caught in orbit, just like the International Space Station orbits the Earth, you can put light in orbit around a black hole if you get really close. So it's basically the photons are orbiting around so that your eyes are receiving the same information from the back of your head that you are looking at so you can see the own back yeah

that is so dope i'm sorry but what is interesting is inside a black hole um you know there's this whole black holes are dark and all that lore is completely true from the outside. But black holes can be bright on the inside because the light from the entire galaxy can fall in behind you. And so as you're on your way towards the singularity, the light travels faster than you do. And it can catch up to you.

And you can watch the entire history of the galaxy unfold sped up for you the future history the future history we could watch the earth find out what happens with the whole climate change thing believe me we already know you can watch all the stars in the galaxy expire i mean depending on how long you take to get down there and so it actually is quite bright for you inside a black hole. It's like all that light gets crushed towards you as you're falling towards the singularity. So it's dark in front. It's dark outside and bright inside.

Right. Because light can't escape, but the light is still in there. The light can fall in. So the light overtakes you because you're just falling at a rate of gravity, but the light is coming in at the speed of light. That's right. And it's all crushed together. So you see a very bright white flash of light

just as you're approaching the singularity. And it's like, you know, the light at the end of a tunnel. Right. It's like a near-death experience, except it's a total death experience. A total death experience. Is your head still attached to your body? That's about it.

It's a total death experience. It's more like attached to your body? That's about it. It's a total death experience. It's more like looking into the arc at Raiders and like, it's beautiful, and then your face melts. All right, so we've gotten this far and on Einstein's gravity. But we know, or at least the equations tell us, that all this matter collapses down to a singularity, which disturbed Einstein. There's got to be something that stops it.

So is this the edge of general relativity's relevance in the universe? Because aren't we dividing by zero there? Yeah, the singularity is what it really is, is it's predicting. For those who don't remember from their math class, you're not supposed to divide by zero, okay? So we have a condition here where your equations blow up. Yeah, you're getting an infinite curvature,

infinite gravitational energy density. And I don't think anyone really believes that that's what actually happens. So you have to abandon general relativity in that spot. I think it's like general relativity is signaling its own failure. And it is saying, when you get to those high energy scales,

we know that we have to invoke quantum mechanics. Because as you said, quantum is of the very small. So here you're in a very tiny, tiny region of space where the energy is very high. And there's no way you can talk about it without understanding quantum gravity. And we don't understand quantum gravity so we know that the singularity isn't a declaration of what's true we know that it's telling us that we need

to understand quantum gravity before we'll really know what's going to happen in the center but don't we have the same problem with the quantum that we do with black holes is that we can't see the quantum well you mean in the in the center the we can't see the quantum in a conventional human way because we're a big macro scale but we've learned to probe the quantum in a very compelling way that we have it it's the most accurate predictions in the history of science we get from quantum mechanics that are confirmed by experiment. So it is stunning. It is something we don't really understand very well. It's very elusive.

It's really spooky, freaky predictions. It's very spooky, freaky predictions, but the accuracy exceeds the accuracy of any scientific prediction in the history of human culture. So if you're a betting man, you would say that at the singularity, quantum physics absorbs general relativity. It's going to rewrite the story, and it might rewrite the story with little things like wormholes. So it might be that as you get into, this might be a crazy idea. I actually don't think it's that crazy.

But that when you get to the quantum scale inside the black hole, you realize that there are these little wormholes, quantum wormholes that are negotiating the interior and the exterior of a black hole without traveling, inducing faster than speed of light travel. And in fact, one of the really spooky ideas is that in fact, the black hole is totally made up of these quantum wormholes. the black hole is totally made up of these quantum wormholes. And so it's like, imagine embroidering a circle and you look like you have this big dark shadow, but when you look closely, you realize it's just these tangles of thread. And so at the quantum level, we might realize that the black hole, its shadow, the event horizon, all of it is really woven out of these quantum wormholes. Chuck, you got that weed ready? I'm telling you.

Jesus. That's like wild. It is wild, and that's how the Hawking radiation would get out. I got one for you. I got one for you. You ready? I ran the numbers on this because large black holes are not on average dense other than the singularity big black holes have slightly different macroscopic properties like you uh how should i say so

let me put another way if you take the mass of the universe and then I ask it, how big a black hole would the mass of the universe make? What would be the size of that event horizon? And it's the size of the horizon of the universe that we observe. So is the entire universe a black hole as seen from the outside of our event horizon and are we

simply alive enjoying the contents of our own black hole well we better get to enjoying it quick because we all about to be crushed into nothing that's for sure i'm just asking well i mean it's an interesting suggestion i would not say the universe is a black hole, but I would say we do have an event horizon as well cosmologically. So inside the universe, we're looking at the expansion of the universe. And there is a region which we can very well articulate around us beyond which light will never reach us. It is also an event horizon.

So the universe goes dark for us beyond that point. There are things we will never reach us. It is also an event horizon. So the universe goes dark for us beyond that point. There are things we will never see. That's everything you said about the black hole. Yeah, that's right. It's the universe of black hole. It's still not a black hole because we're not. The thing about a black hole is it's not just this region of space that you can travel around and paddle and survive forever. Once you cross that event horizon, that singularity is actually a point in your future. So I want to emphasize this. If I look at the black hole from the outside, I think that there's a center to it because it's spatial.

I think it's round. I think there's a point in the center. That point might be the singularity. And if you fall in, maybe you could avoid it. But when you're the person falling in, your space and time have rotated so much that that singularity is actually not a point in space for you at all. It's a point in time. And that singularity is in your future.

And you can no more avoid it than you can avoid flowing forward in time. I got to go. Y'all have a good night. I hope y'all enjoy the rest of the conversation. Wait, so you mean this literally, not just figuratively. Yeah, I mean it literally. The black hole is in front of me in space. From the outside, you see there's a point in space.

Across the event horizon, the rotation of the coordinate system is such that the center is a point in your future. What I would want to think of as a position in space that I might sidestep, it's no longer a position in space. It is on my timeline, and I cannot avoid it, and I'm going to get crushed at that singularity.

It is now an inevitability, Mr. Anderson. Yes. Exactly. Damn. That was a quote from The Matrix, in case you didn't see. Yes. My name is Neil.

Sorry. We're just geeking out here right now so this is spooky stuff all right now i can try to get another one for you i have a book on my shelf co-written by stephen hawking i read it and didn't completely understand it but i do remember the pages where it said that on the other side of a black hole an entire other space-time opens up, as though it has birthed in another universe. That's a really profound idea. So what's really going on there? It's the Hawking and Ellis book, right? Yes, Hawking and Ellis. Very technical, very technical. Beautiful book. So what they did... To me, it was an ugly book because I didn't understand it. To Janet, it's a beautiful book.

It was painful, though. It was painful. So the idea is really... Oh, I can't wait to read it. What they're doing there is they're saying, you know, this is kind of relevant to your question earlier about cosmology. The Big Bang singularity looks a lot like kind of the inverse of a black hole singularity. So instead of everything falling out of the universe,

falling out of the black hole, everything in the Big Bang is coming out of the singularity. And so they were like, well, maybe I should just sew these two things together. And the interesting thing is mathematically in this very formal technical book, they can prove that the space times mathematically can be sewn together flawlessly.

And that's not a given. Wow. Right? And it's beautiful and you can sew them together. So they And that's not a given. Wow. Right? And it's beautiful, and you can sew them together. So they said, oh, maybe when you start to go into the singularity, you're actually blown out into a new Big Bang. And that's another beautiful thing, is that the black holes might be small on the outside

in the way we've described, but they're much, much bigger on the inside. Like the TARDIS. It's the TARDIS. It's Doctor Who's TARDIS. And they can be as big as an entire universe on the inside. Like the TARDIS. It's the TARDIS. It's Doctor Who's TARDIS. And they can be as big as an entire universe on the inside. And that's a beauty of curved space-time allows you that kind of trickery. So it doesn't mean that we have a prediction that that's what happens. It's just suggestive that the math permits it. All right. let's get even more freaky before we close this out.

So you mentioned wormholes possibly being the fabric of a black hole. But how about the wormholes in the science fiction sense where I'm over here, but now I walk through a portal and then I'm over there, as is displayed in the Marvel superhero Doctor Strange or, of course, Rick and Morty, right? Okay?

So much better. Okay. So is there anything that prevents that? Because clearly, if that can exist, it's going to be used in some Einstein theories. Yeah, so wormholes are, again, a mathematical possibility that we don't understand how they're possible it might be like black holes before we realized they were real um so we don't understand what source of

matter or energy will keep that throat open they tend to want to collapse and so we don't know of any form of matter energy in the actual universe that keeps wormholes open and allows us to trans it's got to be like a negative gravity. But they're totally fine. It's got to be kind of a negative gravity. We don't know of anything. But look, there's dark matter, dark energy, and we don't know what those are either. So nobody should say we will never discover a form of energy

that can keep a wormhole open. But, you know, who knows? Maybe it will be related to the dark energy or the dark matter. So it is perfectly fine to attach space-time with these little bridges. That part's completely easy to understand. Nothing wrong with that. Last bit, Jana, before we call this out. In the movie

Interstellar, one of the more poignant, stupefying scenes was when the spaceship was orbiting a black hole. I think they call it Gargantua. And there were a black hole that had a planet. And some of the crew went down to the planet closer to the black hole

because the planet is orbiting the black hole. And they stayed far away. They had completely different timelines. Tell me about time dilation around a black hole. Yeah. We actually even see the effect around the Earth. The rate at which literally our clocks tick is slower, closer to the Earth than it is further away.

So when we communicate with satellites, there's actually the additional effect of the speed of the satellite, which I do believe causes a greater dilation. But we do see that there's... Well, you can run the math. It's actually less than the gravity. It is less than the gravity?

Yeah. So it happens, but around a black hole, it's so extreme that this is part of the rotation of space and time that we were just discussing. So one astronaut stays far from the black hole. They both have perfectly calibrated clocks. The other astronaut travels near and near in the black hole. And as they do, it's almost as though they're rotating in space time, such that their clocks are running slower and slower and slower relative to the person further away. When you hit that horizon, technically you've rotated

all the time away. That's why the center of the black hole is in the future time direction and not in the space direction. I'm literally not expecting anyone to understand that. Like nobody. So what happened, if you didn't see the scene, those 11 of you who didn't see the movie, then security should have removed already. Right, so the astronaut who stays far away. So the astronauts up here, when we're down on the planet with them,

and 20 minutes goes by. Right. And then they beam, or I forgot how it got, back up to the ship. Right. And the folks on the ship are gray. 20 years.

And they age 20 years. Yeah. And they're like, why didn't you call? Yeah. They've spent 20 years. And this is a real effect. We literally see the effect

even around the Earth. We correct, our phones correct for the relativistic time dilation so that Uber can find us. Where they took atomic clocks and they did exactly that? Where one… That was 40 years ago. Yeah. Keep up with the century here.

It's exactly what you're saying. It's proven because there's an actual experiment. Well, it's also proven because we know that there are subatomic particles which have incredibly short lifetimes. If they're just sitting in your laboratory, they decay in a fraction of a second. But you boost them near the speed of light, and they will appear to live for minutes. Wow.

It's real. So you were saying your cell phones. So the origin of that is the GPS satellites. So the GPS satellites. So the GPS satellites are in a different gravitational field from us. So their clocks take at a different rate because of general relativity. Yet all of our clocks are synchronized and perfect because we pre-correct the GPS time for general relativity so that it's correct on Earth time.

That's science. All right. So, yes. So let me get some, just some closing thoughts. Jenny, what can you tell us? Just about life, the universe, and everything. Your career being emboldened by JWST. I'll tell you, my husband always wants to know what's inside a black hole.

So now I'm going to go home and tell him I learned what's inside a black hole. Okay, Janet. Closing thoughts. Okay, Janet. Closing thoughts. Well, I do think it is quite amazing that black holes are like fundamental particles. They're fundamental to the universe in a way that nothing else is,

that we don't really understand. So when the universe was created, it might have made black holes in the same way it made electrons. They might be a fundamental property of the universe. And have made black holes in the same way it made electrons. They might be a fundamental property of the universe. As opposed to an exotic thing that only some telescopes... We think of them as collapsed dead stars, and that is a brilliant way that nature thought of to make black holes, just kill off some stars. But they actually are not dead stars. That's just one

vehicle for making them. And we do think that black holes might have been created in the early universe and they were as heavy as a little pile of sesame seeds, but they were smaller than a proton. And those quantum black holes would have evaporated away like firecrackers. But they are a very profound and fundamental property of the universe.

All right. So, Chuck, do you have a... I do. I have several closing thoughts. But really, I am so proud to see a theater full of people as we discuss these mind-expanding principles, these mind-expanding principles, and we talk about things that are so incredible with respect to our being and the fact that we can look up and look out and wonder. And the fact that you are here gives me hope for this entire stupid rock that we are all floating around. So I'd like to maybe offer some closing thoughts myself.

That one of the things we've noticed about the universe is that every time a new telescope comes online, a new telescope, not just that it's brand new and shiny, but that it was conceived to access the universe by looking through a window that previously had not been opened, by looking through a window that we didn't even know was there.

At some point, someone has to say, I think there's something on the other side of this window because I just discovered this new window and no one's looked through it before. So we gather funds, we propose, it gets peer-reviewed, and the telescopes get developed once again by engineers to empower the science that we have. And what a journey this has been. We are in the centennial decade of the discovery of quantum physics. That was in the 1920s. And you know what actually happened? 97 years ago, Edwin Hubble discovered that our galaxy wasn't the only galaxy in the universe. That the fuzzy things that half of the Messier had found were whole other galaxies.

In a sense, island universes they were poetically referenced as. He was using the biggest telescope available in the day. And so every time we do this, our minds are not only blown, when we put it back together, our minds have actually expanded. And we learn more and more about our place in the universe. So one of the greatest gifts to civilization are the discoveries in astrophysics, because we all look up at night. Yet when the stars call to you, and they call to me, I know maybe you don't become an astrophysicist, but if you walk out at night and it's not cloudy and the moon isn't out, those stars are screaming. And you've experienced this, not in the Northeast. You visit, all right, you go someplace, okay?

You know what I'm talking about. The universe calls to you. So I would claim that the study of the universe opening up these great portals, not only the theoretical portals, but the technological portals to the universe, that there's no greater source of a cosmic perspective than all the new understandings that come down the pipe, that tell us how big the universe is, how old the universe is. And then in a way, looking back on earth, it makes earth all the more precious. Today, looking back on Earth, it makes Earth all the more precious.

In the vastness of the universe, this is the only place we've got. Are we the shepherds we need to be to assure our own survival on our own planet so that the next generations can be proud of the decisions we've made rather than embarrassed by the decisions we didn't. And black holes are just another part of that glorious story. A little more obscure, really fun, good fodder for science fiction storytelling, but I wouldn't have it any other way. That is a cosmic perspective.

That is a cosmic perspective. Now, that's it. Star Talk at the Keswick Theater, Philadelphia. Thank you. Thank you. Jen Eleven. Jenny Green. Chuck Nice!