Quantum Quandary: StarTalk Live! With Brian Greene & Janna Levin

Why three dimensions? Neil deGrasse Tyson and comedians Chuck Nice and Hasan Minhaj celebrate 100 years of quantum physics and everywhere it’s taken us, joined by theoretical astrophysicists Brian Greene and Janna Levin.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  Coming up on StarTalk, we have StarTalk Live at the Beacon Theater in New York City. We're celebrating the 100th anniversary, decade, of the discovery of quantum physics. Not only that, the 1920s was when we discovered that the Milky Way galaxy was not alone in the universe, and that the universe itself was expanding. So, we brought out the big guns for that one. We've got Jan Levin and Brian Greene, two cosmologists with whom you are most familiar, and a very special comedic guest, Hasan Minhaj. So join me and Chuck Nice as we host that evening, coming up.

• 0:44Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 1:01Neil deGrasse Tyson?

  So before we begin, I just want to, I didn't know this until today, that the two of you are actually current collaborators on some research. Could you just highlight what that is? What are you doing?

• 1:11Janna Levin?

  I mean, Brian and I have been working together for years. Mostly, we've been thinking about extra spatial dimensions, and different cosmological implications, implications for theoretical physics, you know, hiding some dark energy in some extra dimensions.

• 1:26Neil deGrasse Tyson?

  As one does.

• 1:27Janna Levin?

  As one does, yes.

• 1:29Neil deGrasse Tyson?

  You're thinking about higher dimensions?

• 1:31Janna Levin?

  Yes.

• 1:32Neil deGrasse Tyson?

  Because the three plus time dimensions are not enough for you?

• 1:35Janna Levin?

  Well, you know, even Einstein, when he started working, wondered why three? I mean, it's a curious question, once you start...

• 1:43Chuck Nice?

  Well, it's a magic number.

• 1:44Janna Levin?

  Yeah? Is it your favorite number?

• 1:48Chuck Nice?

  Wait, those are Schoolhouse Rock people right there.

• 1:51Neil deGrasse Tyson?

  They count to three.

• 1:53Chuck Nice?

  They got it right away.

• 1:58Neil deGrasse Tyson?

  Okay, but how many dimensions are there, really?

• 2:01Brian Greene?

  We don't know, but certain theories tell us that it could be much more than the ones that meet the eye, so it could be as many as 10 or 11.

• 2:10Neil deGrasse Tyson?

  Oh, like gender!

• 2:16Brian Greene?

  I said it, and now I'm getting arrested.

• 2:20Neil deGrasse Tyson?

  Alright, but did you just make up other dimensions? I mean, it sounds like you're pulling it out of your ass.

• 2:29Brian Greene?

  Yeah, it's all...

• 2:30Neil deGrasse Tyson?

  You didn't deny that immediately.

• 2:34Brian Greene?

  Well, partly it is, but it was also deep mathematical reasons that lead us to these ideas.

• 2:40Janna Levin?

  Yeah, and you know, we figure if nature can try some experiments, she will. So, every possibility might actually happen.

• 2:48Neil deGrasse Tyson?

  Okay.

• 2:49Janna Levin?

  So, we're just exploring.

• 2:51Neil deGrasse Tyson?

  Alright.

• 2:52Chuck Nice?

  How much weed do you guys smoke?

• 2:57Neil deGrasse Tyson?

  Alright, so...

• 2:58Janna Levin?

  Complete silence.

• 3:01Neil deGrasse Tyson?

  The microscope and telescope were invented 400 years ago. And, like I said, they take us to the grandest visions of our understanding of our place in the universe. And the tiniest visions that also give us an understanding of our place in the universe. And so, this, those first steps were magnified at the dawn of the 20th century, especially through the 1920s. And so, let's start out with the large, and we'll end with the small, okay? So, let's go back to the roaring 20s. Let's just do that.

• 3:40Neil deGrasse Tyson?

  And here's something that it's hard to even believe, that just 105 years ago, we didn't know if there were other galaxies. We just thought all the stars in the night sky,

• 3:56Neil deGrasse Tyson?

  the Milky Way was the entire universe. There was no, we weren't given reason to think anything else. There were these fuzzy things in the sky, okay, they're just fuzz. We call them nebulae, which is Latin for fuzz.

• 4:10Brian Greene?

  For fuzz.

• 4:10Neil deGrasse Tyson?

  Yes, thank you. So...

• 4:12Brian Greene?

  So, you just thought it was just space lint?

• 4:14Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 4:16Janna Levin?

  Sure.

• 4:16Neil deGrasse Tyson?

  And, but some fuzz lint, space, now you're messing with me. Nebulae, some nebulae were spiral shaped, and others were irregular. And the irregular ones were found in the plane of the galaxy.

• 4:34Neil deGrasse Tyson?

  Whereas the spiral ones were in every direction you looked. Interesting. So, that was odd. It was a first thing. Well, maybe we can unpack this. And figure out what's going on. So, there was a famous debate. Took place in nineteen twenty. At the National, hosted by the National Academy of Sciences. Between. Heber D. Curtis. Unfortunate name. Yeah, that name. And Harold Shapley. Soon to become the director of the Harvard College Observatory. And Heber Curtis was director of the Allegheny Observatory. Two very different. Yeah, I'm gonna say, one of those sounds more expensive.

• 5:18Neil deGrasse Tyson?

  Alright, so, they debated whether these spiral things were other galaxies. With a term coined by. Immanuel Kant in the seventeen hundreds. Who thought about this? Philosopher. Yes, Chuck?

• 5:36Chuck Nice?

  No, Brian, Brian did it to me, man. I'm sorry.

• 5:40Neil deGrasse Tyson?

  What did Brian do to you?

• 5:41Chuck Nice?

  Because he knows I can't hear the name Immanuel Kant without. Being twelve years old. I'm so sorry.

• 5:51Neil deGrasse Tyson?

  Okay, so he, he's a philosopher, deep-thinking philosopher. He looked up and he saw these spiral objects. And he, he thought of them as possible island universes. Oh, that's, that's pretty cool. An island universe. That's beautiful. That is. But we didn't have evidence to say that, to, to support it, but it was a deep idea at the time. So, there they are. They debated this. And. But based on what evidence? Just hot taken? They're scientists. Okay, alright. Which means. Sometimes we have rose-colored glasses towards the past. Yes, I get it, I get it. So, here's how it works. Two scientists argue. There's a pact implicitly signed before they even begin. Which is, either.

• 6:37Neil deGrasse Tyson?

  You're right and she's wrong. You're right and he's wrong. Or you're both wrong. They know this going into the conversation.

• 6:47Chuck Nice?

  It's nerd thunder dog. So. Two scientists enter. Two scientists leave, but one's a little embarrassed.

• 7:02Neil deGrasse Tyson?

  Pay-per-view, Saturday night. So, so, so here's what.

• 7:07Speaker 04

  This is their Tyson, Jake Paul, real kinda throwdown.

• 7:10Neil deGrasse Tyson?

  So let's go to the Harvard fellow.

• 7:12Speaker 04

  Yeah.

• 7:13Neil deGrasse Tyson?

  Cause you can always tell a Harvard man, but you can't tell him much.

• 7:17Speaker 04

  Oh, got it, got it. Also, they were insufferable back then as well. Were they also like, "I went to school in Boston." Fuck you. Just say it, just say it. Say it, you know? I don't know.

• 7:34Neil deGrasse Tyson?

  Alright, so here's what happened. Shapley was heavily invested in the entire night sky being part of the, being the whole universe and the Milky Way. And he had evidence at the time from a fellow astronomer who had looked at the spiral nebulae and claimed that he found them having moved on the sky. Now, if you're really, really far away, that's essentially impossible to measure. But if you're close up and you're moving, you can see that movement. Okay? Things that are close to you.

• 8:13Neil deGrasse Tyson?

  The example here is, if I see a plane moving across the sky and then I see a bird moving at the same angle, I don't conclude that the bird is going 600 miles an hour. The bird is much closer. So at much lower speeds, I can see it cross my field of view. So, because it's closer.

• 8:34Neil deGrasse Tyson?

  That evidence suggested that the spiral nebulae were nearby and he he bet on that horse, but it was the wrong horse.

• 8:45Chuck Nice?

  Mm.

• 8:46Neil deGrasse Tyson?

  He was, he was doing what a good scientist will do. He took the data, put his confidence in the data. It was later shown that the data he was basing his argument on was false. It could not be verified by the work of other scientists. In fact, no, the spiral nebulae had no motion across the sky. And so Shapley was just wrong.

• 9:08Chuck Nice?

  Mm.

• 9:09Neil deGrasse Tyson?

  Later, we would later show that he's wrong. And what puts the nail in the coffin? 1923. Edwin Hubble.

• 9:21Chuck Nice?

  Oh, the man.

• 9:22Neil deGrasse Tyson?

  Hubble was a person before he was a telescope. Yeah.

• 9:27Speaker 04

  I thought he, he was born a telescope.

• 9:29Neil deGrasse Tyson?

  Born a telescope.

• 9:31Speaker 04

  Yeah, just like when you're a kid, you're like, of course, you, there was Ninja Turtles and they were birthed.

• 9:37Neil deGrasse Tyson?

  Yeah, there it is, there it is. So he had an idea based on evidence and it turned out to be wrong because the evidence was flawed. So this is some lessons there, alright? And if one scientist has one bit of evidence, you don't alert the authorities yet until there's confirming of their experiments to do so.

• 9:58Chuck Nice?

  That is, uh, what the peer review is all about, right?

• 10:01Neil deGrasse Tyson?

  That's peer review is all about.

• 10:02Chuck Nice?

  And by the way, for anybody who wants to know, uh, scientists are haters. Okay, that is what they do. You come up with something and somebody goes, I call bullshit and then it's on. Then it's just on.

• 10:16Speaker 04

  Wait, so Neil, so Neil, a peer review to, to us non-scientists is basically, it's scientific group chat where you present your take or information.

• 10:27Neil deGrasse Tyson?

  Yes, yeah.

• 10:28Speaker 04

  The seventeen other friends that are in the group chat get to be like, well, shit.

• 10:32Neil deGrasse Tyson?

  And Shapley had a, had a green bubble in, in the chat.

• 10:36Speaker 04

  Oh, goddamn. Goddamn, what a horrible, what a horrible life to live. He was the one green.

• 10:43Neil deGrasse Tyson?

  He was the one green.

• 10:44Speaker 04

  Surrounded by blues.

• 10:46Neil deGrasse Tyson?

  Yeah, if you have an idea and it's shown to be wrong, then it's just wrong. In fact Einstein, after his relativity, which we'll get into in a couple of minutes,

• 10:57Neil deGrasse Tyson?

  that was hard to accept by people, right? It was, you know, it was hard. It was very counterintuitive. Someone came up with a work saying a hundred against Einstein. A hundred against Einstein. And then he's rumored to say what after that?

• 11:13Janna Levin?

  Let's see, I just learned this anecdote, but he's rumored to have said, "Why a hundred? If I'm wrong, one would have been enough."

• 11:22Chuck Nice?

  Wow.

• 11:23Neil deGrasse Tyson?

  Yeah.

• 11:23Janna Levin?

  It's pretty great.

• 11:24Chuck Nice?

  Yeah. And believe me, I've been married for 27 years, that is right.

• 11:33Neil deGrasse Tyson?

  Okay, so here's what happened. So Edwin Hubble is curious about the spiral nebulae, and he finds a star in them that matches a kind of star that's not in a nebulae, that's just sort of nearer by than that star. It's a very specific kind of variable star, named after the very first of its kind, Cepheid variable. The first of its kind was found in the constellation Cepius. And so that's how we categorize types of variable stars. The first one in a constellation, all the others, no matter where you find them, are that variety. Found a Cepheid variable there, and what was spe... Tell us what's special about the Cepheid variables.

• 12:15Janna Levin?

  Well, they have a very predictable property where their luminosity, how bright they shine, is related to a sort of oscillation. And so you can tell that you're looking at precisely one of those. It's very easily identifiable.

• 12:29Neil deGrasse Tyson?

  If you get the luminosity out of it,

• 12:31Janna Levin?

  Yeah.

• 12:31Neil deGrasse Tyson?

  then you can say, "I can see the period vary."

• 12:34Janna Levin?

  Right.

• 12:34Neil deGrasse Tyson?

  Based on that period, I know how bright it should be.

• 12:37Janna Levin?

  How bright it should be. So it's as though you knew your light bulb, right?

• 12:41Neil deGrasse Tyson?

  Yeah.

• 12:41Janna Levin?

  You can tell if you have a very bright light bulb far away, or a very dim light bulb up close.

• 12:46Neil deGrasse Tyson?

  Right. How can you distinguish the two?

• 12:48Janna Levin?

  And how do you distinguish the two if you know nothing about the light bulb? But if you know everything about your light bulb,

• 12:52Neil deGrasse Tyson?

  Yes.

• 12:53Janna Levin?

  you know exactly what it is, then you can say, "Oh, I know this light bulb, and so I know exactly how far away it is."

• 12:57Neil deGrasse Tyson?

  So he says, "This star is of this particular luminosity, and the only way it can be that dim?" Is if it is far outside our galaxy.

• 13:06Janna Levin?

  I just recently saw the actual plate and it's really stunning. He crosses out.

• 13:11Neil deGrasse Tyson?

  The photographic plate.

• 13:12Janna Levin?

  Yes, the photographic plate where he makes this detection. He wrote NOV, I think for Nova originally. He thought it was a different kind of object. And then he crosses it out and writes VAR exclamation point for a variable star. So it's a real epiphany that he realizes. He knows what he's seen and right at that moment, he understands it's far away.

• 13:34Neil deGrasse Tyson?

  So Emmanuel Kahn. Turned out to be right. These were in fact island universes. And Hubble wrote to Shapley on this. And I had to look this one up. Shapley, what's the quote here? He said, here's the letter that destroyed my universe.

• 14:09Speaker 05

  I'm Kais from Bangladesh and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 14:27Brian Greene?

  It's important to know what he actually meant by that because Hubble himself never was convinced that these were actually other galaxies. He proved that there was something beyond the outskirts of our galaxy. We knew our galaxy about 100,000 light years across. His analysis showed this to be 900,000 light years. We now update it to 2 million light years. But Hubble was so conservative that he was unwilling to then say this is an island universe. This is a galaxy in its own right.

• 15:01Neil deGrasse Tyson?

  What an idiot.

• 15:03Speaker 04

  Wait, what's the difference, just from a space real estate standpoint? What's the difference between an island universe and a galaxy? What are we talking?

• 15:10Neil deGrasse Tyson?

  They're poetically identical.

• 15:11Speaker 04

  They're the same. They're the same.

• 15:13Neil deGrasse Tyson?

  Poetically identical.

• 15:14Speaker 04

  Got it.

• 15:15Neil deGrasse Tyson?

  Yeah.

• 15:16Speaker 04

  Okay.

• 15:16Neil deGrasse Tyson?

  Yeah, because if our galaxy is our universe and is another galaxy, then you get to call that a universe. Except, once we see the full breadth of it all, we gotta reallocate how we use the word "universe." Because it's uni-verse. One in...

• 15:35Speaker 04

  One verse. Right. But we're in the, we're in the multiverse. Spider-Man. We're in the...

• 15:43Neil deGrasse Tyson?

  We'll get to that.

• 15:45Speaker 04

  Okay.

• 15:46Neil deGrasse Tyson?

  Yeah, yeah, yeah, we'll get to that.

• 15:47Speaker 04

  All right.

• 15:47Neil deGrasse Tyson?

  Minus the Spider-Man, but we'll...

• 15:51Speaker 04

  You didn't like the second one?

• 15:54Speaker 04

  I thought it was great.

• 15:56Neil deGrasse Tyson?

  So, so, Jana, how did... We're reeling from the fact that we are not the universe, we're just a part of a universe. And then a few years later, Hubble discovers that the spiral nebulae are in motion, body and soul. So what's going on there?

• 16:16Janna Levin?

  Yeah, so, once he's starting to be able to use these Cepheid variables and these standard candles to get a strong sense of how far away things are, he can start to do that, he can start to do that kind of mapping out the local environment, what we have right nearby, and then also galaxies further away, these little smudges on the sky. And he begins to catalog not only that there are other galaxies around us at great distances, but there also seem to be receding away from us, largely, predominantly.

• 16:46Neil deGrasse Tyson?

  Yeah, and so he makes a plot of this.

• 16:48Janna Levin?

  Makes a plot. So this is very strange. I mean, you're looking at all of these enormous galaxies. So a galaxy is a collection of hundreds of billions of stars, and they're pretty localized, and maybe they're spirals and blobs, and they're very far away. And they're also moving away from us in every direction. Which is very peculiar. So he makes this plot. It's completely freaky, but it gets freakier because the further away they are, the faster they're expanding away from us.

• 17:13Speaker 04

  And they're calculating this all without computers?

• 17:16Janna Levin?

  Well...

• 17:16Speaker 04

  Hundreds of billions of stars.

• 17:17Janna Levin?

  People were called computers back then.

• 17:21Brian Greene?

  Sure.

• 17:22Neil deGrasse Tyson?

  Yeah, if you look at old dictionaries, look up the word "computer," a person who makes computer.

• 17:26Janna Levin?

  The person who computes, yeah, so.

• 17:28Neil deGrasse Tyson?

  But wait, and there's a room full of-

• 17:31Janna Levin?

  And yes, but they're doing it without the machines.

• 17:33Neil deGrasse Tyson?

  There's a room full of computers at Harvard at the time.

• 17:35Janna Levin?

  Yes, so he actually uses the work of one of the Harvard computers, which was a woman named Henrietta Levin, and she was part of a group of women who worked at the Harvard Observatory that were called-

• 17:45Brian Greene?

  And she talked like this.

• 17:49Janna Levin?

  Well, they were called Pickering's harem because Charles Pickering, at one point, was so frustrated with his male computers that he fired them all, and he said, "My maid could do a better job," and he hired his maid, who was Wilhelmina Fleming, and she did a great job.

• 18:04Janna Levin?

  And she hired all these other women, and one of whom was Henrietta Levin, and she made thirty cents an hour.

• 18:12Janna Levin?

  Go ahead, Henrietta.

• 18:14Neil deGrasse Tyson?

  Are we applauding her or her pay? That was weird.

• 18:19Brian Greene?

  Thirty cents an hour, that's it.

• 18:23Neil deGrasse Tyson?

  She should be making iPhones. Okay, so-

• 18:27Brian Greene?

  I said it. I said it.

• 18:32Neil deGrasse Tyson?

  All right, so, but mixed in here, we've got simultaneous things going on. Einstein's general theory of relativity is already at the races, okay? So that came in in nineteen fifteen.

• 18:44Brian Greene?

  Fifteen.

• 18:45Neil deGrasse Tyson?

  Okay? That gave us a mechanism to understand what the whole universe could be doing, to just catch us up on that.

• 18:53Brian Greene?

  Well, Einstein writes down his equations in nineteen fifteen, and initially he applies them to things like the motion of the Earth around the Sun, and terrestrial and nearby motion, local things. But then, some other very creative thinkers, one in particular was a Belgian priest named Georges Le Mettre, he-

• 19:18Brian Greene?

  Decide to apply the mathematics not to something in the universe, but to the entirety of the universe, and find from the equations that the universe should be expanding over time. It should be slowing.

• 19:30Neil deGrasse Tyson?

  Robert, just to be clear, he was able to do that not based on his training as a priest. He was a priest physicist.

• 19:39Brian Greene?

  He was a priest physicist, but no doubt his interest in applying these ideas to the entirety of the universe was not distinct from his focus on the big questions of existence. So they weren't that separate, although he, in his own mind, was very clear. He said, "There are two ways to have deep insight about the world. There's mathematics and there's salvation." And he said, "Let me follow both." And that's what he did.

• 20:07Neil deGrasse Tyson?

  But not intermingled?

• 20:08Brian Greene?

  He was very clear not to...

• 20:10Neil deGrasse Tyson?

  There was a line in the sand between the two. Wait, so what, so, so... Le... le mat...

• 20:17Brian Greene?

  I'll let you guys figure out the pronunciation.

• 20:20Neil deGrasse Tyson?

  So, he takes the equations. We have an expanding universe. But he, so, Le Matzer...

• 20:26Brian Greene?

  Before, before Hubble.

• 20:28Neil deGrasse Tyson?

  Le Matzer predicts an expanding universe. Using Einstein's equations. So Einstein could have made the prediction, and he didn't.

• 20:34Brian Greene?

  Yeah, in fact, in 1917, Einstein actually got there first. And when he applied the equations to the entirety of space, was very disturbed that he couldn't get a universe that met his own philosophical prejudice.

• 20:47Neil deGrasse Tyson?

  Which was?

• 20:48Brian Greene?

  That the universe is fixed, eternal, static, and unchanging.

• 20:51Neil deGrasse Tyson?

  Why would anybody think the universe could be anything other than that?

• 20:55Brian Greene?

  Well, I mean, there is this book called Genesis, which seems to suggest a beginning. So there are some people who think perhaps that that vision is not correct. But Einstein, and many others at the time, very firmly believed that the universe could not change on the largest of scales.

• 21:12Neil deGrasse Tyson?

  And that's just a philosophical bias.

• 21:13Brian Greene?

  Totally. And in fact, he changes...

• 21:16Neil deGrasse Tyson?

  Wait, wait, wait, how could he get away with that if all the galaxies have gravity? And if they all feel each other's gravity, they would all collapse down into one point?

• 21:24Brian Greene?

  Yeah, so this was an argument that Isaac Newton actually gave hundreds of years ago. Earlier, but if the universe is infinitely big, and if the galaxies are spread across an infinity of space, then there is no center for them to collapse toward.

• 21:39Neil deGrasse Tyson?

  Got it.

• 21:39Brian Greene?

  So you can envision a static universe now.

• 21:42Neil deGrasse Tyson?

  If it's infinite.

• 21:43Brian Greene?

  If it's infinite.

• 21:44Neil deGrasse Tyson?

  If and only if.

• 21:44Brian Greene?

  But even more than that, Einstein then, in his own general relativity, recognized basically the issue that you're raising in a finite universe. And he said, "Let me introduce a repulsive push to counter the attractive pull of gravity."

• 22:01Neil deGrasse Tyson?

  An anti-gravity.

• 22:02Brian Greene?

  An anti-gravity force field called the cosmological constant. So he introduces this into the math in 1917. It was not in the 1915 equations. He introduces it just to have a static universe that will allow him to breathe easy.

• 22:17Neil deGrasse Tyson?

  And to fulfill his philosophical bias. Then the mantra says, "We can have an expanding universe." And so how did Einstein react to that?

• 22:25Brian Greene?

  Einstein learns of this from Le Maitre in 1927. And he says to Le Maitre, "Your calculations are correct, but your physics is abominable."

• 22:37Neil deGrasse Tyson?

  Oh, them's fighting words.

• 22:38Brian Greene?

  They were fighting words. By which he was saying, "You can't trust that every mathematical calculation tells you something real about reality. Some math should be in math textbooks, and it's interesting, but it's nothing more than a mathematical curiosity." And he says, "Le Maitre, your idea of an expanding universe, that's a mathematical curiosity. It's not real."

• 22:56Neil deGrasse Tyson?

  Okay, so then, 1929, Hubble discovers an expanding universe. Now what? What happens next?

• 23:04Janna Levin?

  Well, so it's interesting, because the way I originally described it is kind of confusing. You might think it makes it seem like we're at the center of this expansion, and everything's receding away from us. But the way the Hubble Law is specifically, it's much more like the space between every galaxy is actually stretching. So from their point of view, if you were on one of those other galaxies, it would also look like everything's receding away from.

• 23:24Neil deGrasse Tyson?

  You're moving away from them.

• 23:25Janna Levin?

  Right, everything's receding away from. And if you imagine that it's not the galaxies literally moving on spacetime, but actually the distance between the galaxies that's stretching, then something further away is actually moving away from you faster. There's more space stretching. And this was really closer to Le Maitre's. Description, not even closer, it simply wasn't static.

• 23:47Speaker 04

  So just so I'm clear, at that time, they believed there's only one galaxy in approximately nineteen twenty-five. Just so I'm following.

• 23:53Neil deGrasse Tyson?

  Uh, it-

• 23:54Speaker 04

  I feel like I'm in a Chris Nolan right now.

• 23:56Neil deGrasse Tyson?

  No, no, no, no.

• 23:56Speaker 04

  Watching Tenet, let me just, let's pause real quick.

• 23:58Neil deGrasse Tyson?

  No, no, up until nineteen twenty-three, twenty-four.

• 24:00Speaker 04

  One galaxy.

• 24:01Neil deGrasse Tyson?

  One galaxy, it wasn't one galaxy.

• 24:03Speaker 04

  We are the main character.

• 24:03Neil deGrasse Tyson?

  It was one universe.

• 24:04Speaker 04

  One universe, copy.

• 24:05Janna Levin?

  Yes.

• 24:06Speaker 04

  Here we are, twenty twenty-five, from what I understand.

• 24:08Neil deGrasse Tyson?

  Yes.

• 24:08Janna Levin?

  Now there's other-

• 24:09Speaker 04

  How many, how many universes are we in now?

• 24:11Brian Greene?

  But are you talking island universes, or are you talking universe universes?

• 24:14Speaker 04

  I'm talking about the whole-

• 24:15Brian Greene?

  Oh, good God, there's one universe that we know about. Filled with a hundred billion galaxies, each of which has on the order of a hundred billion stars. There are theoretical ideas that Neil suggests we might get to tomorrow. That, that speak to the possibility that there might be other universes. So the answer is, we don't know for sure.

• 24:35Speaker 04

  Okay.

• 24:35Brian Greene?

  But the data seems to suggest that there's one universe.

• 24:38Speaker 04

  Well, we, we were talking about this backstage. If the, the delta is that big between those two numbers, which is one and, which you just basically said a gajillion. How do we, how do we know that, that what we're living in right now, the data that we know right now, isn't gonna be wildly off? And fifty years from now, or a hundred years from now, they'll be like, look at those dum-dums in twenty twenty-five.

• 24:59Brian Greene?

  We hope, we hope that that's what will happen.

• 25:02Janna Levin?

  Yeah.

• 25:02Brian Greene?

  That's what we live for. We live to be- Wrong! Stupid. We live to be wrong, we're scientists!

• 25:09Speaker 04

  Oh, got it.

• 25:14Speaker 04

  We live to be wrong, we're scientists. Got it, okay.

• 25:19Neil deGrasse Tyson?

  Well, so let's, let's follow through this reasoning. We discovered expanding universe, if we're expanding, that means we're bigger today than we were yesterday. And bigger yesterday than we were the day before. So, logically, where does that take us?

• 25:35Janna Levin?

  Bigger?

• 25:36Neil deGrasse Tyson?

  No, no, going back in time.

• 25:37Janna Levin?

  Oh, I'm sorry, so yes, so if you're already disturbed about the lack of permanence to the universe, then this very quickly leads you to have even greater existential dread, because if you run the movie backwards, then everything was once closer together, and if you keep running the movie backwards, it gets to a point which seems quite catastrophic, where these galaxies are literally on top of each other. And eventually, you're kind of imagining something that's so dense that you have to start thinking of it as hot and, soupy and, and, and chaotic and-

• 26:10Janna Levin?

  Then what?

• 26:12Neil deGrasse Tyson?

  What did Le Maitre call this?

• 26:14Brian Greene?

  Yeah, so Le Maitre basically said, "Look, if the math is saying that the universe is expanding today, and if then Hubble's data shows that the universe is expanding today, just wind the cosmic film in reverse." You run the film backwards and things get closer and closer together, and there suggests that there's a point in the distant past when everything was on top of everything else, and he calls this the primeval atom. This is the beginning, according to his description.

• 26:42Neil deGrasse Tyson?

  Okay, I happen to know there was an astronomer active at the time, very brilliant guy, named Fred Hoyle, who was not into a universe that would be changing.

• 26:52Brian Greene?

  Yeah.

• 26:53Neil deGrasse Tyson?

  He knew the universe was expanding, he couldn't reason that away.

• 26:55Janna Levin?

  He accepted that.

• 26:56Neil deGrasse Tyson?

  Yeah, he accepted that, but if you're expanding but you're always the same, that must mean matter is being spontaneously created in the void to create new galaxies, so that statistically, the universe always looks the same.

• 27:11Brian Greene?

  Yeah.

• 27:12Chuck Nice?

  You know, but here's the thing, if the universe is expanding, that in itself is a change, so why would you not accept a changing universe?

• 27:19Neil deGrasse Tyson?

  Because he wanted to always look the same for all of time, for all eternity, in the past and in the future. Again, it's a philosophical bias.

• 27:27Janna Levin?

  But I think the idea of the beginning was particularly disturbing. The idea, so this primeval atom that Le Maitre was talking about...

• 27:34Neil deGrasse Tyson?

  Is it disturbing to scientists but not for religious people, where God made the universe? They're perfectly happy with the beginning.

• 27:39Brian Greene?

  Look, Pope Pius XII, perhaps the nerdiest pope in history, who loves science...

• 27:45Neil deGrasse Tyson?

  Wait, why do you know this?

• 27:46Brian Greene?

  He, I don't know, he took Le Maitre's work, and he said, "There is the scientific evidence for Genesis." That's what he said. And when Le Maitre heard this, he threw a fit.

• 27:59Neil deGrasse Tyson?

  Belgian priest, Le Maitre.

• 28:01Brian Greene?

  That's right.

• 28:02Neil deGrasse Tyson?

  The pope is talking to him.

• 28:03Brian Greene?

  Not directly, but yes, when he catches wind that this is what the pope is saying, and one of his students, who was in the class that Le Maitre had to teach that afternoon after learning, says that Le Maitre, who normally is very quiet and mild-mannered, he came in and ranted for 45 minutes, because his whole point was, "I am not blending my religious life and my scientific life, and here the pope is taking my scientific work and he's turning it into religion."

• 28:29Chuck Nice?

  But notice, he said all that to a student and not the pope.

• 28:37Neil deGrasse Tyson?

  You don't want to know the Galileo situation. Exactly. Yeah, so I have a tamer version of that quote. It's, "As far as I see, such a theory of the primeval atom remains entirely outside any metaphysical or religious question."

• 28:52Brian Greene?

  Yeah, that's after I had a couple of drinks and chilled.

• 28:56Neil deGrasse Tyson?

  Okay, so, so then it got called the Big Bang by...

• 28:59Brian Greene?

  By Fred Hoyle.

• 29:00Neil deGrasse Tyson?

  By Fred Hoyle.

• 29:01Brian Greene?

  Yeah, so Fred Hoyle was in a 1948 BBC Radio interview.

• 29:05Neil deGrasse Tyson?

  Why do you know this level of detail about this?

• 29:07Brian Greene?

  I don't know. And so, he is describing his own approach, which as you mentioned, is this steady-state approach where matter is created spontaneously and fills in the gaps in space. And so, they ask him about this other approach, not his. And he says, "Oh, that theory in which all matter must be created in one Big Bang", and that's where the idea of Big Bang theory comes from. Now, people have interpreted that as a derogatory description. His own way of recounting the story is, he was simply trying to draw a distinction between a theory in which, in his steady-state, only a little bit of matter is created here and there across space versus this other theory...

• 29:51Neil deGrasse Tyson?

  Like one hydrogen atom per century, per cubic light year. I mean, there's some small rate...

• 29:58Brian Greene?

  Not quite that small. So, it is one atom per century, per Olympic-sized swimming pool.

• 30:03Neil deGrasse Tyson?

  Oh, okay, I thought it was bigger than that.

• 30:04Brian Greene?

  And that's all that you need. And so, it's kind of an amazing thing.

• 30:07Neil deGrasse Tyson?

  In the whole universe, yeah, yeah.

• 30:08Brian Greene?

  Yeah, because what's more believable? That one little atom forms in a cubic, you know, in a swimming pool-sized arena of space per century? Or that there's this moment where everything is created all at once? Framing it that way, his theory sounds perhaps a little bit more believable.

• 30:24Neil deGrasse Tyson?

  Less crazy.

• 30:25Brian Greene?

  Yeah.

• 30:26Neil deGrasse Tyson?

  Yeah. So, what do we have to assume if there is a Big Bang? So, we've got to assume that the expansion has been uniform the whole time.

• 30:35Brian Greene?

  No, it doesn't have to be uniform.

• 30:36Neil deGrasse Tyson?

  No?

• 30:37Brian Greene?

  Yeah, it can change over time.

• 30:38Neil deGrasse Tyson?

  Well, that's been always expanding.

• 30:39Brian Greene?

  It's always expanding.

• 30:40Neil deGrasse Tyson?

  Okay.

• 30:40Brian Greene?

  Yeah.

• 30:41Neil deGrasse Tyson?

  And...

• 30:42Janna Levin?

  Unless there's extra dimensions, those might...

• 30:44Brian Greene?

  All right.

• 30:45Neil deGrasse Tyson?

  They could expand differently in a higher dimension.

• 30:47Janna Levin?

  Brian and I will talk about it later. Well, yeah, you can squeeze the other dimensions. There could have been chaotic mixing of the expansion and contraction, but overall, the overall volume of the universe was expanding.

• 30:58Neil deGrasse Tyson?

  But the way you get this is looking at the rate at which the universe is expanding.

• 31:02Brian Greene?

  Yes.

• 31:02Neil deGrasse Tyson?

  And that is a slope on a graph. And Hubble first derived that. And it's, there's a slope. It's just, he called it a letter C, which is for constant. But since then, we swapped that out with a capital H for Hubble.

• 31:19Brian Greene?

  Yep.

• 31:19Neil deGrasse Tyson?

  And we call it the Hubble constant. Very famous Hubble constant.

• 31:22Janna Levin?

  So it's constant over space. I mean, it's not necessarily over time.

• 31:25Brian Greene?

  Yeah, it's important to realize, it's really the Hubble parameter, we should call it, because it does change in time.

• 31:29Janna Levin?

  It was, it could have been faster in the early universe, faster in the future.

• 31:33Neil deGrasse Tyson?

  All right, so Hubble, he had the wrong, turned out, the Cepheid variable he used, he didn't know at the time, there were two varieties of Cepheid variables. The one that's near us and the one that you can see from far, far away. And he presumed they were the same, no reason to think otherwise.

• 31:52Brian Greene?

  Right.

• 31:53Neil deGrasse Tyson?

  So he got the wrong distance, the wrong expansion rate of the universe.

• 31:57Chuck Nice?

  So Cepheid is like diabetes, is type 1 and type?

• 32:00Neil deGrasse Tyson?

  Yes, there's a type 1 and type 2, exactly, I think.

• 32:07Janna Levin?

  Maybe not exactly.

• 32:09Neil deGrasse Tyson?

  Yes, there's literally type 1 Cepheid and type 2 Cepheid. And you gotta use apples and apples when you're doing this exercise. So, so he got an age of the universe of 2 billion years. We would later refine these numbers. When I was in graduate school, many moons ago, the uncertainty in the Hubble constant was a factor of 2. There was a 10, so with, with the Hubble constant, you run the film backwards, ask how much time, at this expansion rate, looking backwards, when do we get to time zero?

• 32:43Chuck Nice?

  That makes sense.

• 32:44Neil deGrasse Tyson?

  Well, yeah, just, just when is everybody in the same place at the same time? That's a perfectly sensible question.

• 32:49Brian Greene?

  Yeah.

• 32:49Neil deGrasse Tyson?

  And we got two numbers, there are two camps.

• 32:51Brian Greene?

  Okay.

• 32:51Neil deGrasse Tyson?

  A 10 billion year camp.

• 32:53Brian Greene?

  Okay.

• 32:54Neil deGrasse Tyson?

  And a 20 billion year camp. A fact, a whole factor of 2. And everyone is, you know, fighting for their, and we know they both can't be right. And so, we need better data. One of the goals of the-

• 33:09Brian Greene?

  Wait, isn't, isn't being off by 10 billion quite a bit?

• 33:13Speaker 04

  That's a lot. Again, cop a median and I only took physics one in undergrad. I did not advance, not, I don't want the smoke, but I am saying being off by 10 billion is a lot.

• 33:24Neil deGrasse Tyson?

  Here's the thing.

• 33:25Speaker 04

  Like if you go out to dinner and we split it and I'm off.

• 33:30Speaker 04

  By that, like that big of a delta, if I'm fif, if I'm, yeah, if I'm 100% off.

• 33:35Neil deGrasse Tyson?

  Yes, yes.

• 33:37Speaker 04

  Aren't you like, you lose your science little thing?

• 33:41Neil deGrasse Tyson?

  No, no.

• 33:42Speaker 04

  You know what I mean? Like, you've been disbarred?

• 33:45Neil deGrasse Tyson?

  Right, right. Here's the thing.

• 33:46Speaker 04

  But you know, you just get to talk your shit?

• 33:48Neil deGrasse Tyson?

  Here's the thing.

• 33:49Speaker 04

  You're off by 10 billion, you get to talk your shit still.

• 33:52Neil deGrasse Tyson?

  Here, here's the thing.

• 33:53Speaker 04

  Like my dad in the fucking living room when he's giving his opinions about politics. He just gets to run his mouth continuously?

• 34:00Neil deGrasse Tyson?

  I got this.

• 34:01Speaker 04

  Go ahead. This is me and my, this is a me and my dad thing, but I'm just a little mad that, that, that a capital S scientist was this off.

• 34:08Neil deGrasse Tyson?

  Okay.

• 34:09Speaker 04

  Go ahead. And I have a second question, but go ahead.

• 34:11Neil deGrasse Tyson?

  The universe is vast.

• 34:14Speaker 04

  Yes.

• 34:14Neil deGrasse Tyson?

  In time.

• 34:15Speaker 04

  Yeah.

• 34:16Neil deGrasse Tyson?

  And in space.

• 34:17Speaker 04

  Sure.

• 34:19Neil deGrasse Tyson?

  It is vast in every metric we've ever established for it. There are things that are vast in size, in temperature, in speed, in gravity. And so if I'm off by a factor of two between 10 billion and 20 billion.

• 34:44Speaker 04

  Yeah.

• 34:45Neil deGrasse Tyson?

  I could have been off by a factor of 10, by a factor of a thousand, by a factor of a million. We were quite happy we were in the same sandbox having that conversation.

• 34:56Chuck Nice?

  So it's kind of, it's kind of like being Jeff Bezos, you know? If I'm off by 10 billion, eh, not so bad.

• 35:04Neil deGrasse Tyson?

  So, so.

• 35:07Speaker 04

  Could I also ask you the second philosophical question, which is?

• 35:09Neil deGrasse Tyson?

  Sure.

• 35:10Speaker 04

  Which is, no, no, no, this is, this is for real. When you, when you were like, it's either 10 billion or 20 billion. And I was asking you this backstage, which was if, when the number is that big, is it almost like the United States' debt? Where they're like, the, the deficit is at 28 trillion. And you're like, what does it even matter now?

• 35:26Neil deGrasse Tyson?

  Yeah.

• 35:26Speaker 04

  It's at a gajillion manillion. Like, what does it matter?

• 35:29Chuck Nice?

  Well, when I'm done.

• 35:30Speaker 04

  Why does the number, because I feel like a freshman in college.

• 35:32Chuck Nice?

  When I'm done, it's gonna matter an awful lot.

• 35:40Janna Levin?

  I would say that actually 10 billion is actually quite good. 10 to 20 is very much in the ballpark.

• 35:46Speaker 04

  You should run the Federal Reserve.

• 35:49Speaker 04

  Yeah, yeah.

• 35:50Janna Levin?

  This stage, you know.

• 35:51Speaker 04

  Pretty funny. This is a good way to think about it.

• 35:53Neil deGrasse Tyson?

  You could have been off by a trillion.

• 35:54Janna Levin?

  Well, but the future is going to be much, much longer than the past. So it's not as though the universe kind of will expire within another 10 billion years like we're confined to this number. The future could be just a huge number. We could be living in a time where it's not 10 billion.

• 36:07Brian Greene?

  But can I just give you perhaps one, these are all very, very good answers. But perhaps one other way of looking at it.

• 36:12Speaker 04

  You're saying it was a bad question? Bad question? Your great answer is bad question?

• 36:16Brian Greene?

  We don't care whether it's 10 billion or 20 billion. The number doesn't matter. What does matter is.

• 36:22Speaker 04

  That's the most American answer, by the way. That's the most American answer.

• 36:26Brian Greene?

  Here. The truth is, we don't care, but we want our theories to work. We want our theories to make predictions that match with observations. That's the only thing that matters to us. The actual answer that comes out, whether it's 10 billion or 50 billion.

• 36:41Neil deGrasse Tyson?

  Or 42.

• 36:42Brian Greene?

  Like you're saying, it just doesn't matter. But we need to have a consistent description so that we have evidence that we know what we're doing, because evidence matters.

• 36:50Neil deGrasse Tyson?

  And both sides could not be right.

• 36:52Brian Greene?

  Right.

• 36:52Neil deGrasse Tyson?

  And so when the Hubble telescope was launched, okay? I'm just getting out of graduate school. It is launched. The number one goal set for that telescope was to resolve that discrepancy. The telescope's named after the guy who gave us the Hubble constant in the first place. Within two or three years, we nailed it. And the Hubble constant, its value would give us an age of the universe at about 14 billion years, which is comfortably between those two extremes. And that's science working at its best. It was, there's a limit to how much we can keep beating each other over the head. Let.

• 37:31Neil deGrasse Tyson?

  Let's get more data. Let's build a telescope that'll solve this.

• 37:34Brian Greene?

  And in fact, today, there is a similar argument happening. It's not between 20 billion and 10 billion, which, as you say, is a factor of 2 or 100% difference. Now, we're down to the 5% difference. We understand things that well, that we have 2 groups that are 5% apart, describing a number of years, billions of years into the past, and that's the precision with which we can do it, within 5%.

• 38:01Chuck Nice?

  And they will kill each other.

• 38:04Brian Greene?

  So again, we don't care the exact number. We care that we can describe it with that level of precision when we're talking about events that happened billions of years ago. That's the mind-bending.

• 38:15Neil deGrasse Tyson?

  And here's the issue. When it was 10 and 20 billion, you always have to report your uncertainties for a number in science. And those uncertainties had a little bit of overlap in the middle. And it landed where you expected it to land. Now that we have 2 other warring factions on the value of the Hubble constant, those 2 numbers are within 5% of each other, but the uncertainties are tight. So the uncertainties don't overlap. And if you look at, go Google search on Hubble tension, and that's what will come up.

• 38:47Janna Levin?

  Adam Rees is coming to Pioneer Works in October. I just planted an ad.

• 38:53Janna Levin?

  Adam Rees, who's a Nobel Prize, one of the Nobel Prize winners, who discovered that the universe is not just expanding, the expansion's getting ever faster, it's accelerating, who is part of this Hubble tension debate, will be speaking at Pioneer Works on the Hubble tension.

• 39:08Chuck Nice?

  Without waxing philosophical, I just don't want to miss this point that we're not actually saying, which is what makes science so incredibly great is exactly what you all just demonstrated. It is this pursuit of the truth based upon the best available information at the time. So it's okay if it's wrong. Because when it's right, we're gonna get there.

• 39:40Neil deGrasse Tyson?

  Yes.

• 39:46Neil deGrasse Tyson?

  You got it.

• 39:49Neil deGrasse Tyson?

  Alright, so, we're turning the clock back. And, we get to the Big Bang. And, but, now the universe, large-scale universe described by general relativity, is now small. It is so small, you extend, the equations go back, the universe is the size of an atom. Does quantum physics apply to the entire universe? Or only to atoms? Where does that, where are you on that, both of you?

• 40:19Janna Levin?

  Well, at this point, we feel we have to invoke quantum mechanics to understand what was happening in the Big Bang. The energy scales are so dramatic, and that we're really probing quantum physics. High energies, you're really looking, somewhat surprisingly, at small scales. So, we are still trying to grapple with what the Big Bang is telling us about the potential to understand not just general relativity, but a kind of quantum variant of that, if there is such a thing.

• 40:50Neil deGrasse Tyson?

  Yeah, so I got general relativity, I got quantum physics. Do they make nice in the sandbox?

• 40:56Brian Greene?

  It's a deep and difficult question, and one that I and many others have spent their lives trying to answer, and we do not fully have the answer yet.

• 41:04Neil deGrasse Tyson?

  Let me restate that.

• 41:05Brian Greene?

  Yeah.

• 41:06Neil deGrasse Tyson?

  That you and others have spent your lives failing to answer.

• 41:09Brian Greene?

  Yes, I agree.

• 41:10Neil deGrasse Tyson?

  But I think we established that's okay.

• 41:14Brian Greene?

  You hear that? Ah, take that.

• 41:16Neil deGrasse Tyson?

  Okay, you got a fan over here, alright, go.

• 41:18Brian Greene?

  No, it's exactly the case. So, when you take Einstein's equations of the general theory of relativity, and you try to invoke quantum mechanics within the same calculations, which as you eloquently noted, you'd have to do. If you're talking about the whole universe, when it's incredibly small, you need Einstein's general theory of relativity. It's the whole universe, after all. But you also need quantum physics, because it is so small, and that's the theory that describes the small things. And when you try to simply put the equations together, you get one answer out from almost any calculation, which is infinity.

• 41:56Brian Greene?

  And that might sound, "Oh, that's interesting, a big, deep, mystical number." No, it's nonsense. Infinity is nature's way of grabbing us by the lapel and slapping us around and saying, "You're doing something wrong. You've got to figure this out."

• 42:08Neil deGrasse Tyson?

  So I've heard another one, that's where... Infinity is where God divides by zero.

• 42:12Brian Greene?

  Yes.

• 42:12Neil deGrasse Tyson?

  Yeah.

• 42:13Brian Greene?

  Stephen Hawking, yes.

• 42:14Neil deGrasse Tyson?

  Yeah. Oh, Stephen Hawking said that.

• 42:16Brian Greene?

  Well, at least that's what he's attributed to.

• 42:17Neil deGrasse Tyson?

  Okay, okay. So, but, you're saying they don't make nice in the sandbox?

• 42:22Brian Greene?

  Yeah.

• 42:23Neil deGrasse Tyson?

  So, there's a limit. What's this Planck length? What's going on there?

• 42:28Janna Levin?

  Well, the Planck length is the scale at which...

• 42:32Neil deGrasse Tyson?

  Named after who?

• 42:33Janna Levin?

  After Max Planck, the...

• 42:37Brian Greene?

  I love how you say "Max."

• 42:38Janna Levin?

  I don't know, is it... What do you think?

• 42:40Brian Greene?

  I say Max Planck.

• 42:41Neil deGrasse Tyson?

  Max, okay.

• 42:43Janna Levin?

  Well, 100 years ago, in the early discoveries of quantum mechanics, was thinking about whether the universe was discrete or if it really was a continuum. And if I looked, for instance, at the air in this room, if I look closer and closer, do I find out it's actually made of individual molecules moving around and is not actually a continuum? And same with water. Was thinking about these things.

• 43:10Neil deGrasse Tyson?

  In other words, water is not infinitely divisible. You get to a molecule at some point.

• 43:14Janna Levin?

  Eventually, you get to an individual quanta, a little particulate, a discrete bundle. And in thinking about this, there was sort of a fundamental scale that we would say is when we can definitely no longer think in a way where we're ignoring this quantum scale, where we're forced, as Brian's describing. Beyond that, we're definitely going to strike an infinity. But by the Planck length, we're in trouble. We really should be trying to understand the theory of gravity at a quantum level. Maybe that means that spacetime is coming in little individual bundles. I don't even know how to think about that. I'm just thinking about correlations between little tiny...

• 43:55Neil deGrasse Tyson?

  You're saying spacetime is coming?

• 43:56Brian Greene?

  Yeah. That was a wild...

• 43:58Neil deGrasse Tyson?

  Say that?

• 43:58Brian Greene?

  That was a wild sentence.

• 44:00Neil deGrasse Tyson?

  Yeah, that was very Game of Thrones.

• 44:02Brian Greene?

  Spacetime is coming.

• 44:06Janna Levin?

  Well, I mean, if it came from the Big Bang, I mean, was it the moment that space and time was in fact created? And are we thinking about things of a continuum of spacetime itself?

• 44:16Brian Greene?

  Brian, how big is that smallest unit? The Planck length is 10 to the minus 33 centimeters. And again, I know the question will be, well, you know, how do you think about something that's so small? What does it matter if it's 10 to the minus 33 or 10 to the minus 31? And again, we don't care about the exact value, but that's where the mathematics takes us. And just to get a feel for that, if you were to take an atom and, well, take a tree. Take a tree and expand it to be the size of the observable universe? A tree? Yes. Then the Planck scale, that tends to minus 33 centimeters, would expand roughly to the size of an atom. So the Planck scale is to an atom as a tree is to the universe.

• 45:00Brian Greene?

  That's how tiny the distance we're talking about here. And why, I'm gonna channel Hason now.

• 45:06Chuck Nice?

  And so you measure this with a ruler?

• 45:08Brian Greene?

  Yeah, I know, I'm gonna channel Hason. Can I channel you right now?

• 45:11Speaker 04

  You can channel me. I'm not gonna even pretend like I understand what's happening right now. I'm gonna be 100% honest. There's like 3,500 people here and I'm like, don't act like you know.

• 45:22Brian Greene?

  I'm gonna channel you.

• 45:23Speaker 04

  You lost me at spacetime is coming. And by the way, you came in quite hot, Brian, and you're like, I know what you're thinking. And that's not what I was thinking. I was thinking, I think it's really incredible, let's just have a quick little tangent here. I think it's really incredible. It is almost 9:00 PM and this many people went on Ticketmaster.com. Paid fees, you way back there, up there, yes. Way up there, yeah. You guys paid tickets to learn about space nebulae. It really, it was very heartening. So that's what I was thinking about, Brian. It's actually like, you know, when people say this country's going to shit and math and science is at an all-time low? I'm like, you know what? It's, it's the math and science lovers. I feel like we could theater on a...

• 46:10Speaker 04

  Yeah, of all things you could be doing at 9pm, just...

• 46:15Neil deGrasse Tyson?

  So, I'm channeling Hassan here.

• 46:18Speaker 04

  Sure.

• 46:18Neil deGrasse Tyson?

  What, why do you have any confidence at all that you know what's happening on a scale that's small?

• 46:26Speaker 04

  We don't.

• 46:27Neil deGrasse Tyson?

  Oh, okay, that's it, that's it. Thank you. Oh, Chuck, come back.

• 46:32Speaker 04

  Thank you, you guys. We don't know anything and we could be off by a whole lot. Good night, take care. Thank you, Beacon.

• 46:40Neil deGrasse Tyson?

  No, no, so, so, let me see if I can unpack this.

• 46:44Speaker 04

  Yeah.

• 46:46Speaker 04

  Oh, we're gonna figure it out right now?

• 46:47Neil deGrasse Tyson?

  Yeah.

• 46:48Speaker 04

  Okay, sure.

• 46:49Neil deGrasse Tyson?

  Is it true that every prediction we've ever made with quantum physics, when we've been able to test it, has come true?

• 46:56Speaker 04

  Absolutely.

• 46:57Neil deGrasse Tyson?

  Okay, is it true that in general relativity, we already know what its boundaries are? Because there are calculations you cannot make because of this infinity problem?

• 47:08Speaker 04

  Absolutely.

• 47:09Neil deGrasse Tyson?

  Therefore, if one of those is going to succumb to the other, it sounds like Einstein has to...

• 47:16Speaker 04

  He's gonna have to bow down to the quantum.

• 47:18Neil deGrasse Tyson?

  He's gonna have to...

• 47:19Speaker 04

  That's what's happening.

• 47:20Neil deGrasse Tyson?

  Bend the knee to the quantum.

• 47:21Speaker 04

  He's gonna bend the knee to the quantum.

• 47:22Neil deGrasse Tyson?

  So, either quantum will absorb Einstein, or there's a higher level understanding that'll absorb them both.

• 47:29Janna Levin?

  I would say it's, it's, that's true, but also, quantum isn't in competition. We have theories of matter, for instance, nuclear forces that we understand, they can be quantized, right? Theory of electromagnetism can be quantized. So, there are laws of physics, and quantum mechanics is a regime in which we're understanding the highest energy attributes of those laws of physics. Now, gravity, Einstein's general relativity has replaced the theory of gravity with this theory of spacetime, this theory of geometry.

• 48:02Neil deGrasse Tyson?

  Replace Newton's theory of gravity.

• 48:03Janna Levin?

  Replaces Newton's theory of gravity, but it is one of those forces. It should sit with the matter forces and have a classical regime, meaning a regime in which we don't have to worry about quantum mechanics, things look smooth, we understand general relativity works beautifully.

• 48:17Speaker 04

  Regime sounds very political.

• 48:18Neil deGrasse Tyson?

  It does, it does.

• 48:19Speaker 04

  Dictator.

• 48:20Neil deGrasse Tyson?

  Totally does. Dictated by.

• 48:23Speaker 04

  It sounds very, very USSR. It sounds very Kim Jong-un like.

• 48:28Janna Levin?

  Unfortunately, it's true everywhere.

• 48:28Speaker 04

  Okay, got it, okay.

• 48:29Janna Levin?

  But then, when we go to the early universe, like the Big Bang or in the cores of black holes, where, where things start to get very extreme, we want to be able to quantize. That law of...

• 48:41Neil deGrasse Tyson?

  As we have quantized other things successfully...

• 48:43Janna Levin?

  It's not gonna replace gra... Exactly, it's not gonna replace gravity. We wanna quantize gravity, and that seemed like a perfectly reasonable request.

• 48:50Neil deGrasse Tyson?

  Okay, so Einstein's equations are not quantized.

• 48:53Brian Greene?

  Yeah.

• 48:53Neil deGrasse Tyson?

  They require continuum.

• 48:55Brian Greene?

  Yeah.

• 48:55Neil deGrasse Tyson?

  So how do you quantize gravity?

• 48:56Brian Greene?

  Good, so Jan is describing the history as very insightful and useful. So, we had an equation for electricity and magnetism that came from Maxwell. We were able to blend that with quantum mechanics, giving us quantum electrodynamics. It works. We had equations describing the strong and weak nuclear forces. We were able to embed quantum mechanics into those theories. Works wonderfully well. When we try to play exactly the same game with Einstein's theory of gravity, general relativity, and try to put quantum mechanics in there to quantize it, it just doesn't work. So what does that mean?

• 49:33Neil deGrasse Tyson?

  It means you're not smart enough to...

• 49:35Brian Greene?

  Well, it's interesting. It could be that we're not smart enough, and I'm full well willing to take that as the ultimate answer, but there's a lot of evidence, if you allow me to come right up till today for just a moment, I know you want to go temporarily...

• 49:47Neil deGrasse Tyson?

  This is the centennial, but go on.

• 49:49Brian Greene?

  Yeah, so there's evidence today that Einstein's general relativity, the reason why you can't quantize it, the reason why you can't put quantum mechanics into it, it already seems to have quantum mechanics embedded in a deep and subtle way that Einstein himself didn't recognize.

• 50:05Chuck Nice?

  Oh, please do tell me, because my edible just kicked in, and this is fascinating. I mean, what you're saying right now is revolutionary, because what you're saying is you can't put something into something where the thing is there.

• 50:21Brian Greene?

  If it's already there.

• 50:22Chuck Nice?

  We just don't know where it is inside of that thing, but once we find it in there, we're gonna be like, "Yo, that's where it is!" And be like, "I told you not to put it in there, it was already in there!"

• 50:33Neil deGrasse Tyson?

  Okay.

• 50:34Chuck Nice?

  Amazing!

• 50:35Neil deGrasse Tyson?

  Chuck just blew a gasket. We gotta...

• 50:38Chuck Nice?

  No, that is like, that's like, that's simple, it's elegant, it's profound, it's amazing!

• 50:44Brian Greene?

  I agree.

• 51:12Neil deGrasse Tyson?

  Alright, so, let me, let's back up, back to the roaring twenties. And I just want to go down the list of completely freaky things that quantum physics prescribed that defied anybody's common sense. And, which is why it's still freaky. In fact, what's that quote from, was it Feynman about quantum physics? What did he say?

• 51:34Brian Greene?

  Yeah, there are a few, but if you think about quantum mechanics without getting dizzy, you haven't understood a single, single thing about it.

• 51:41Chuck Nice?

  Oh, then I understand it very well.

• 51:47Neil deGrasse Tyson?

  Okay, so, 1923. The wave-particle duality is proposed.

• 51:54Brian Greene?

  Yeah.

• 51:54Neil deGrasse Tyson?

  So, that's kinda freaky. That particles are also waves.

• 51:59Brian Greene?

  Yeah, it was Prince Louis de Broglie, who basically-

• 52:02Neil deGrasse Tyson?

  He was a prince?

• 52:02Brian Greene?

  He was a prince, yeah. And so, he said, "Look, in 1905 Einstein showed us that light, which we had thought of as a wave, actually needs to be described as a particle. So-called photoelectric effect, that's how he went to-

• 52:14Neil deGrasse Tyson?

  Oh, 05, 1905.

• 52:15Brian Greene?

  1905. And then in 1923, in his PhD thesis, Louis de Broglie says, "Let me do the reverse. Electrons, we always think about them as particles, maybe they need to be thought of as waves." And that is a key moment in-

• 52:30Neil deGrasse Tyson?

  And wasn't his PhD thesis like-

• 52:31Speaker 04

  That was a prince who did that?

• 52:33Neil deGrasse Tyson?

  A prince.

• 52:33Speaker 04

  A prince? I don't believe it.

• 52:37Speaker 04

  I, I, I know current monarchy, not that intelligent. Let's be honest, Harry or William, you're not cooking, you're not cooking this up. There's, there's too much incest. I mean, you know this, you understand science. For you to be operating at that level, so, not buying it. You cheated off someone's paper, not buying it.

• 52:58Neil deGrasse Tyson?

  So, his PhD thesis, if I remember correctly, was like 12 pages long or something?

• 53:03Brian Greene?

  Very short.

• 53:04Neil deGrasse Tyson?

  Very short?

• 53:04Brian Greene?

  Yeah.

• 53:05Neil deGrasse Tyson?

  And he got a Nobel Prize for it?

• 53:06Speaker 04

  It was a 12-page PDF. And he got a Nobel Prize for a 12-page-

• 53:10Janna Levin?

  PhD.

• 53:11Speaker 04

  A PhD paper.

• 53:13Chuck Nice?

  Okay, let me just say, that's the smartest dude ever.

• 53:18Brian Greene?

  Well, that's how, that's how you know he was royalty. He turned in a 12-page PhD paper. They're like, "Doctor Prince." And he's like, "Thank you." Double-spaced, 12-page PhD paper.

• 53:32Neil deGrasse Tyson?

  Tighter margin.

• 53:33Brian Greene?

  You entitled piece of shit.

• 53:35Neil deGrasse Tyson?

  Couple of years later.

• 53:38Brian Greene?

  Sorry, sorry. Neil, you just, I'm sorry, Neil. I shouldn't have, shouldn't have spoken ill of the monarchs there.

• 53:44Neil deGrasse Tyson?

  No, no, I got nothing. This is America. We fought a war to get away from monarchs.

• 53:50Chuck Nice?

  Not for long.

• 54:00Chuck Nice?

  Just give it time.

• 54:03Neil deGrasse Tyson?

  Okay. So, so then Schrödinger came around.

• 54:10Neil deGrasse Tyson?

  Oh, we have a Schrödinger fan up there.

• 54:12Chuck Nice?

  That was the cat.

• 54:13Neil deGrasse Tyson?

  Yeah.

• 54:14Chuck Nice?

  That was the cat.

• 54:17Neil deGrasse Tyson?

  Cat. So, what does Schrödinger do for us?

• 54:21Janna Levin?

  Well, Schrödinger begins to think more abstractly about what's real and what's not real. So, we're used to thinking of particles. You've already described de Broglie and the electron. We think of these little fundamental particles, almost like billiard balls, acting out their lives. And they have some concrete existence. Schrödinger starts to say, "Well, there's wave-particle duality. That's pretty profound. But maybe the only thing that's real is this thing called the wave function, which is the probability for the particle to be in a certain state, to be in a certain location, to be moving with a certain speed. But the particle itself, in some sense, isn't real anymore. If you look for it, sometimes you'll find it in a concrete location.

• 55:05Janna Levin?

  But what is really determined by equations, by the laws of physics, is the wave function, which is this probabilistic description."

• 55:13Neil deGrasse Tyson?

  And the wave function occupies physical space, doesn't it?

• 55:16Janna Levin?

  Yeah, the wave function occupies physical space.

• 55:18Brian Greene?

  Only for, only for a single particle. So, it's a kind of important subtlety.

• 55:23Janna Levin?

  Yeah.

• 55:23Brian Greene?

  For one particle, you can think about this wave function as filling space. If there are two particles, it lives in six-dimensional space. If there are three particles, it's in nine-dimensional space. So, you really can't think of it in these ordinary terms.

• 55:37Chuck Nice?

  Ooh, I am high.

• 55:40Neil deGrasse Tyson?

  Right, okay. So. So, if the particle can be anywhere here, and I have some barrier here, it could show up on the other side of the barrier.

• 55:51Janna Levin?

  Right, but it doesn't actually travel through. So let's say your barrier is a concrete wall. There's some small probability that you would find the particle. The wave function would describe the probability of finding the particle in this region of space, but it doesn't actually, like a billiard ball, travel through the cement wall.

• 56:07Chuck Nice?

  Okay, now, this might be the THC talking, but the way you guys are talking, there just might just be one particle. Like, there aren't a bunch of particles. It's just one particle.

• 56:22Neil deGrasse Tyson?

  I told you he blew a gasket.

• 56:23Brian Greene?

  Well, but, but, but Richard Feynman had the idea that maybe there was one particle that circled around through time and cycled back over and over again, giving what appeared to be many particles now, but there's only a single particle through this temporal cycle.

• 56:39Chuck Nice?

  I just said it.

• 56:42Neil deGrasse Tyson?

  Moving forward and backwards through time.

• 56:44Brian Greene?

  Yep. Oh my god.

• 56:46Neil deGrasse Tyson?

  Okay, okay. Alright, so, but what I'm saying is if a particle can show up on the other side of the barrier, then that's, you guys came up with a word for that, and it's tunneling.

• 56:55Brian Greene?

  Quantum tunneling.

• 56:56Janna Levin?

  It can quantum tunnel through the barrier, but that, but that's the, the point of Schrodinger saying, what's real is just this probabilistic likelihood of finding the particle. The particle itself, in some sense, does not have concrete existence anymore.

• 57:10Neil deGrasse Tyson?

  Okay, so you know what?

• 57:11Janna Levin?

  It challenges the whole nature of reality.

• 57:12Brian Greene?

  No, but, but concretely, there is a probability that we could calculate

• 57:16Janna Levin?

  Yes.

• 57:16Brian Greene?

  for the likelihood of you tunneling through the stage and being underneath the floor. And it's a non-zero probability. It's kinda small, so it's unlikely to happen, but that's what quantum mechanics tells us.

• 57:29Neil deGrasse Tyson?

  But the smaller I get, the more likely it will happen.

• 57:31Brian Greene?

  Exactly.

• 57:32Janna Levin?

  It can happen in the laboratory.

• 57:33Neil deGrasse Tyson?

  Yeah, okay. So, just for context here.

• 57:36Brian Greene?

  Wow.

• 57:36Neil deGrasse Tyson?

  We were trying to understand how the sun made energy. And we did the calculation. Once we determined the sun is mostly hydrogen and it's hottest in the center, we said, "It must be undergoing fusion." And so what you run the math, to undergo fusion, a proton,

• 57:53Brian Greene?

  Yep.

• 57:54Neil deGrasse Tyson?

  the nucleus of a hydrogen atom, has to merge with another proton, the nucleus of another hydrogen atom. Protons have the same charge. Electrostatically, like charges repel. So, they have to be moving fast enough. So that before they have a chance to repel, they stick together and form a new nucleus. Okay. We calculated what temperature that was necessary because high temperatures give you higher speeds. We calculated that temperature and it was 100 million degrees and there was no way the center of the sun was going to give us 100 million degrees. Because you can calculate through sensible laws of thermodynamics what that should be and we were scratching our heads. And then quantum physics comes around

• 58:39Neil deGrasse Tyson?

  and then you invent this spooky magical thing called tunneling. And we discover in our calculations that at a mere 10 million degrees, see, this matters, 10 million, 100 million. At a mere 10 million degrees, they would otherwise not hit, but some of them tunnel through and connect. Tunneling makes the sun's energy production even possible. And I was like,

• 59:12Neil deGrasse Tyson?

  because it's not just some, something that particle physicists worry about in their laboratory. I had to worry about it as an astrophysicist.

• 59:20Speaker 04

  Why are you worried about this? It's okay.

• 59:22Neil deGrasse Tyson?

  Okay. Thank you, thank you.

• 59:24Speaker 04

  The sun's gonna sun, you know? Hell, Robbins, let them, let the sun, let the sun do that.

• 59:30Neil deGrasse Tyson?

  Thank you.

• 59:31Speaker 04

  It's okay.

• 59:33Neil deGrasse Tyson?

  Okay.

• 59:33Speaker 04

  We need you, Neil, don't, don't blow it.

• 59:35Neil deGrasse Tyson?

  Thank you, that's very, very.

• 59:37Speaker 04

  Okay, so tunneling, tell us more, there's a lot tunneling and.

• 59:40Neil deGrasse Tyson?

  So now what about the Heisenberg uncertainty principle? That's, that seems like the biggest thing of them all. Talk me through that real fast.

• 59:46Brian Greene?

  Yeah, I would say so, that's the real moment when the old ways of looking at the world are shown, they have to be jettisoned. Because the old way of looking at the world, what is reality? Reality is stuff that's at a location moving with a certain speed. That's the way we describe the world. And Heisenberg, with the armature of quantum mechanics, says you can't actually do that. You can't specify the location and the speed simultaneously of any object. You can't do it according to the quantum equation. So the very language of reality that we used to use

• 1:00:22Neil deGrasse Tyson?

  No longer applies. Why can't you measure both at the same time?

• 1:00:26Brian Greene?

  Well, if you have a particle described as a wave, right? And you want that particle to have a definite location, that wave has to be highly spiked, so that you can say, ah, almost 100% likelihood it's at this location. But when you see how the notion of velocity comes into quantum mechanics, it has to do with the wavelength of the wave. And so if you want something to have a definite speed, it has to have a definite wavelength. That's not spiky. So to have definite location, you need spike. To have definite speed, you need wave. Those are different shapes.

• 1:01:02Neil deGrasse Tyson?

  And you can't have them at the same time?

• 1:01:03Brian Greene?

  You can't have them at the same time.

• 1:01:04Janna Levin?

  Can I try analogy nowhere near as precise as what Brian just said? But sometimes I like this musical analogy. If you play a chord, which is a whole bunch of notes together, you can play chords, but you can't simultaneously be playing a single note. So the chord is like a superposition of the notes. And how this relates is that when you're in a precise location, what Brian's describing as a sharp spike, you're sort of in a superposition of velocities or momenta. So it's like, it's like the, the location is the note, the, the velocities are the chords, or vice versa. If I know the velocity exactly and I'm playing chords, I'm no longer playing individual, I'm, I'm playing, I can't isolate a single individual note in a superposition of notes.

• 1:01:48Neil deGrasse Tyson?

  So what is, so how does all this connect to the, what they call the observer effect? Where you, I, I want to measure the particle right there. I, I got to look at it, so I shine light on it, and the light sends it somewhere else.

• 1:02:00Brian Greene?

  Yeah.

• 1:02:00Neil deGrasse Tyson?

  So I can't actually ever know what the particle's doing.

• 1:02:03Brian Greene?

  Right. And, and so there's two things in there. One is, as you're saying, to look is to interact. And when you interact, say by bouncing a photon off a particle, you affect the particle.

• 1:02:14Neil deGrasse Tyson?

  Because I need the photon to take the picture.

• 1:02:16Brian Greene?

  That's right. So that's one key point that emerges from these ideas. But the other point-

• 1:02:22Neil deGrasse Tyson?

  So we can never know anything?

• 1:02:24Brian Greene?

  No, no. No, no, this is-

• 1:02:26Speaker 04

  I've started here. That's the crazy thing. Y'all went on this crazy-

• 1:02:30Brian Greene?

  Hello? I'm sorry, I'm sorry. I got it. That is just not right, okay? Quantum mechanics tells us that the things that you thought you could know are not the things that you can know. But with quantum mechanics, we made predictions of the anomalous magnetic moment of the electron to 14 decimal places, using a theoretical calculation. And we've measured it in degrees, decimal by decimal by decimal, on all of those numbers. And that's why we love these numbers. They show us that we understand what we're doing.

• 1:03:06Neil deGrasse Tyson?

  Okay, Brian just blew a gasket.

• 1:03:09Chuck Nice?

  So you can know without knowing, is what you're saying? We can know some things.

• 1:03:14Speaker 04

  Let me say this, Brian. The type of energy you're bringing-

• 1:03:19Neil deGrasse Tyson?

  Alright, wait, wait.

• 1:03:19Speaker 04

  Oh man, you are built for CNN. This type of panel smoke? Oh, fantastic.

• 1:03:26Neil deGrasse Tyson?

  Yeah. Alright, so this-

• 1:03:28Speaker 04

  You should so be in one of those Street Fighter squares. The decimal to the decimal to the- Yeah, oh, it's great. This is great. This is good stuff. This is good television.

• 1:03:37Neil deGrasse Tyson?

  So, so-

• 1:03:39Speaker 04

  Go ahead, Neil.

• 1:03:40Neil deGrasse Tyson?

  So, this, this observer effect-

• 1:03:42Speaker 04

  Bring us home with certain-

• 1:03:43Neil deGrasse Tyson?

  Has been widely misapplied by people thinking my consciousness is affecting the measurement.

• 1:03:51Brian Greene?

  Look, there is a big mystery at the heart of quantum mechanics. Even with our capacity to make calculations that agree with observations to the level of precision that I just emphasized, perhaps with unnecessary theatricality, there is, there is a question that we don't know how to answer, which is what you're asking. When you observe, you seem to be able to coax one result, one answer, even though the quantum description embodies many possibilities. We don't understand how that happens.

• 1:04:18Neil deGrasse Tyson?

  Is this the many worlds hypothesis?

• 1:04:20Brian Greene?

  It's, it's one answer.

• 1:04:21Janna Levin?

  But the Schrödinger equation is so beautiful, and it does not actually include in it a way to understand how measurements are made.

• 1:04:29Brian Greene?

  Yes, that's the key point.

• 1:04:30Janna Levin?

  And, and so if you really take the Schrödinger equation very seriously, it simply says there are all of these possibilities, and they're all half-

• 1:04:38Neil deGrasse Tyson?

  So we don't have a theory of measurement? To get us through where we are in the physics.

• 1:04:44Brian Greene?

  Just you know, there are proposals. People have put down mathematical equations that do answer this question.

• 1:04:50Neil deGrasse Tyson?

  What is the many worlds hypothesis?

• 1:04:51Brian Greene?

  The many worlds hypothesis is if you have a description of a quantum system like a particle, and the quantum wave says 30% chance here, 20% chance here, 50% chance over here. When you measure it, you don't get only one result. There's one of you that finds it over here. There's another one of you that finds it over here. And there's a third one of you that finds it over here, but these are all in different universes. Oh, it's Rick and Morty.

• 1:05:20Neil deGrasse Tyson?

  So you just invented multiple universes to explain something you can't otherwise explain?

• 1:05:24Brian Greene?

  The math invented it.

• 1:05:26Neil deGrasse Tyson?

  Thank you, Chuck.

• 1:05:27Brian Greene?

  Wait, wait, wait. That's really important. So this guy named Hugh Everett, in 1957 in Princeton, he studies the math, the very equation that Janna made reference to, the Schrödinger equation. He says to himself, "Let me take the math completely seriously and see where it takes me." And the math takes you, when you look at the paper, it's direct to this possibility of there being multiple universes. It's not made up. It really emerges directly from an analysis of the equations, and the equations make predictions that are confirmed. So you say, "Maybe I should take this math fully seriously," and that's where it takes you.

• 1:06:01Chuck Nice?

  The passion with which Brian is describing this is like me explaining why I have glitter on my face when I come home because I was at an arts and craft fair.

• 1:06:18Neil deGrasse Tyson?

  All right, we're gonna have to land this plane soon. Just briefly, I know you spent your career doing this, but just in 30 seconds, explain string theory.

• 1:06:35Speaker 04

  Twenty seconds, does life have meaning? Go!

• 1:06:38Brian Greene?

  I only need ten. No, look, the old picture was that the fundamental constituents of matter were little dot-like particles. The string idea is that maybe they're little extended filaments. And why do we introduce this idea? When you introduce this idea, quantum mechanics and general relativity do play well in the sandbox.

• 1:06:58Neil deGrasse Tyson?

  Wow. Okay. And that was less than thirty seconds. Whoa, all right, okay. So what's in the future? So I know astrophysically, we don't know anything about dark matter, we don't know anything about dark energy, we shouldn't have even named them, because we don't know enough about them to even name them.

• 1:07:15Janna Levin?

  And they should be called invisible.

• 1:07:16Neil deGrasse Tyson?

  I should, they should be called Fred and Wilma. With no bias. So, or faster than the light, time travel, time travel, faster than the light travel, before the big bang. Is what you're working on, or your peeps, does it address any of this? Will quantum mechanics take us to all the places we need?

• 1:07:36Brian Greene?

  Yeah, I mean, there's zero evidence that quantum mechanics has any cracks whatsoever. It's the only theory that we've written down in the history of science.

• 1:07:44Neil deGrasse Tyson?

  It's the most successful theory.

• 1:07:45Brian Greene?

  Most successful theory.

• 1:07:45Neil deGrasse Tyson?

  Ever.

• 1:07:46Brian Greene?

  And so we introduce this.

• 1:07:47Neil deGrasse Tyson?

  Which gives you confidence to believe crazy stuff that it predicts.

• 1:07:50Brian Greene?

  Exactly. And so we're pressing on, and ultimately, we think putting general relativity and quantum mechanics, either because they're already born together, or because they're blended together, will be the key to answering these questions. We're not there yet, but that's exactly where we're headed.

• 1:08:04Neil deGrasse Tyson?

  And why do you need these extra dimensions?

• 1:08:07Janna Levin?

  Well, Brian was describing string theory, which may or may not be true, but string theory actually requires extra dimensions for it to make sense, for the mathematics to allow gravity and matter and quantum mechanics to play nice together. But even without string theory, the idea that there are extra spatial dimensions is just kind of a natural extension when you start to think about space and time, and you start to take seriously Einstein's ideas. So now we're in the predicament where maybe those extra dimensions are harboring the dark energy. Maybe there's some explanation for the dark matter having to do with the extra dimensions. So now, we can start to think of the extra dimensions as a dark sector that are harboring, really, the resolutions.

• 1:08:49Janna Levin?

  Like, we're observing them already, we just don't have the direct connection, to be certain.

• 1:08:56Neil deGrasse Tyson?

  So they're invisible in plain sight? Is that what you're saying?

• 1:08:59Janna Levin?

  Yeah, I mean, they're literally visible, but maybe dark energy is a consequence of quantum energies, which is a paper Brian and I wrote many years ago. Dark energy. Dark energy, which is driving the universe to expand ever faster, which is something we observe.

• 1:09:14Chuck Nice?

  It is also driving my administration.

• 1:09:19Janna Levin?

  I've got to land this plane.

• 1:09:23Neil deGrasse Tyson?

  Uh, go on, go on.

• 1:09:24Janna Levin?

  Oh, well, just that we might be observing through something like dark energy, indirect evidence of extra dimensions. We can't literally see into them, we can't point to them, we can't move around in them yet, but we are living with the consequence.

• 1:09:37Neil deGrasse Tyson?

  So these could be manifestations

• 1:09:39Janna Levin?

  Yes.

• 1:09:39Neil deGrasse Tyson?

  of these higher order phenomenon in the universe.

• 1:09:42Janna Levin?

  Which is part of the motivation for thinking about them. Perfect sense.

• 1:09:47Neil deGrasse Tyson?

  Thank you, Chuck.

• 1:09:48Chuck Nice?

  All right, just wanted to put a button on that.

• 1:09:51Neil deGrasse Tyson?

  Quote from Einstein in his denial of quantum physics, in spite of him contributing so mightily to the field. He, you described the probabilistic nature, especially from Schrödinger's equation, and Einstein said, "God does not play dice with the universe."

• 1:10:06Speaker 04

  And Niels Bohr retorted, "Einstein, stop telling God what to do."

• 1:10:12Chuck Nice?

  You know, you don't know if God needs to make some money real quick, you don't know that.

• 1:10:16Neil deGrasse Tyson?

  With the dice?

• 1:10:16Chuck Nice?

  Yeah, you know, I can see him down.

• 1:10:21Chuck Nice?

  Papa needs a new universe.

• 1:10:27Speaker 04

  I like how back in the day scientists threw shade at each other very poetically. The way they, you know, kind of shit-posted was very, the use of...

• 1:10:36Neil deGrasse Tyson?

  Well, we have good vocabulary to work with.

• 1:10:38Speaker 04

  Yeah, great vivid language.

• 1:10:39Chuck Nice?

  They still do it the same today.

• 1:10:43Neil deGrasse Tyson?

  The way I'm going to land this plane is offer you a cosmic perspective, something that I'm prone to do when we're exposed to this much information. When I think of the 1920s,

• 1:10:57Neil deGrasse Tyson?

  as a scientist, it may be the most consequential decade ever in the history of science, based on how it influenced our thought, our, the trajectory of our research that would follow, and, but I want to make a slightly different point.

• 1:11:20Neil deGrasse Tyson?

  Before the 1920s,

• 1:11:24Neil deGrasse Tyson?

  What are scientists doing? Well, they're doing sciency things, right? In a lab, there's a chemical, or there's a particle, there's a material.

• 1:11:35Speaker 04

  Merlin Meyer flask.

• 1:11:36Neil deGrasse Tyson?

  Yeah, flask, thank you, Jess. You flesh out the picture of your lab, okay. Suppose it was the 1920s, and you had a friend, relative, or you were a politician, and you heard that someone is working on the structure of atoms and molecules. You'll say, "Why does that matter to anyone? I'm a carpenter, I just care that my wood atoms cut, or that they can be shined, or polished, or painted. Why does that matter to me? I'm making cars in an assembly line. Why does it matter to anybody?" You're taking your brilliant intellect,

• 1:12:18Neil deGrasse Tyson?

  and applying it to something that nobody cares about except your cadre of people. But they will tell you, "Well, it's the foundations of matter." And they'll tell you, "I don't care you're using up national resources to do this." Well, what has happened every time we researched the frontier of science, in basically every frontier of science? Whatever it looks like when you're doing it, it's easy to say, "That'll never apply to anything." Why are you doing that?

• 1:13:00Neil deGrasse Tyson?

  You wait a little while, they're clever engineers, clever other scientists. They see problems in the world, and they see a possible solution? Do you realize today there is no creation, storage, and retrieval of digital information without an exploitation of the quantum? The IT revolution, that is responsible for nearly half the GDP of the world, at some level, was birthed in that decade, at a time when people are just exploring the edge of our understanding of the world.

• 1:13:44Neil deGrasse Tyson?

  Yeah, it would take 50 years, longer than what is typical for an R&D project to show up as a household product.

• 1:13:53Neil deGrasse Tyson?

  But all I can tell you is if you know anyone who says we're doing too much science, or this science is not relevant to me, or I don't know why you're doing this, that doesn't sound like it makes sense.

• 1:14:07Neil deGrasse Tyson?

  What you're doing is you're cutting out at the kneecaps, the legs of a future waves of discovery that could transform civilization. Not only take us to where we might want to go, but possibly solve problems that we might have created for ourselves.

• 1:14:28Neil deGrasse Tyson?

  So,

• 1:14:33Neil deGrasse Tyson?

  there is nothing more shortsighted in this world than anybody running up and saying we should do less science. Because every one of us in this room has been touched by it.

• 1:14:46Neil deGrasse Tyson?

  And there's no greater demonstration of that than the science that unfolded in that decade, the 1920s. That's the quantum side of it. In the astrophysics side, that birthed our understanding of the beginning of the universe and how the sun makes its energy. We would then learn how the stars manufacture elements in their core. We would learn, take a few more decades, exploiting the quantum, applying to other realms of science.

• 1:15:17Neil deGrasse Tyson?

  We would learn that the very ingredients of our bodies, the carbon, the oxygen, the nitrogen, the iron are traceable to stars that underwent thermonuclear fusion following all the rules of quantum physics. And those stars exploded, scattered that enrichment across the galaxy, creating the environment, the chemical ingredients, to make star systems with planets, and on some of those planets, life.

• 1:15:49Neil deGrasse Tyson?

  So that that era not only gave us our IT revolution, it gave us an awareness of ourselves that borders on the spiritual. And it's the fact that not only are we alive in this universe, because of our ingredients are traceable to stars, the universe is alive within us.

• 1:16:23Neil deGrasse Tyson?

  And that is a cosmic perspective. This, this has been StarTalk, live from the Beacon Theater. This is like a fifth time at the Beacon Theater, fifth or sixth time, and you guys have been a marvelous audience for us. We love you all. And... Oh, no, thank you. And, but more than loving you all, we love the support you give for science, because there is no future of civilization without it. We might as well just move back to the

• 1:17:08Neil deGrasse Tyson?

  cave. So, as always, Neil deGrasse Tyson here, thanking our panel. We've got Chuck Nice, Brian Greene, Ken Levin, Hasan Minhaj. Neil deGrasse Tyson, you're a personal astrophysicist, as always bidding you to... Keep looking... Eight of you knew this, okay?

• 1:17:38Speaker 04

  We're gonna do it one more time, come on. All right, here we go. What's the tagline?

• 1:17:45Neil deGrasse Tyson?

  Okay. Neil deGrasse Tyson, you're a personal astrophysicist.

• 1:17:49Speaker 04

  Astrophysicist?

• 1:17:50Neil deGrasse Tyson?

  Bidding you to...

• 1:17:51Speaker 04

  Bidding you to?

• 1:17:52Neil deGrasse Tyson?

  Keep looking up.

• 1:17:53Speaker 04

  Keep looking up, here we go. Remember, it's, he's gonna go, Neil deGrasse has a da-da-da-da-da. And remember, those eight people, they cared. You guys all paid money, rusty currency, a real number that we know, Brian. We know exactly how much you paid to those sharks at Ticketmaster. Them. Now, he's gonna go, Neil deGrasse has a da-da-da-da-da, to keep, and you go, looking up. Here we go.

• 1:18:15Neil deGrasse Tyson?

  Neil deGrasse Tyson, you're a personal astrophysicist, bidding you all to...

• 1:18:20Speaker 04

  Keep!

• 1:18:21Neil deGrasse Tyson?

  Keep looking up.

• 1:18:22Speaker 04

  Looking up.

• 1:18:23Neil deGrasse Tyson?

  All right.

• 1:18:24Speaker 04

  Yes.