Exploring Hidden Dimensions with Brian Greene

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in an extended version of Star Talk. That's right. I'm loving it. All things you never knew you didn't know about what's going on in the universe coming right up. Welcome to Star Talk. Your place in the universe where science and pop culture collide. Star Talk begins right now.

Astrophysicist. Got with me Chuck Nice, baby. What's up, Neil? All right. This is a special Cosmoquaries edition. Okay. Because half of it is not gonna be Cosmoqueries. Oh, okay. Half of it, I'm just gonna be talking to my man. Oh, okay. I th for a moment I yeah, I thought you meant you were just gonna talk. Up the street.

Yes. Professor of Mathematics and Physics and Physics at Columbia University. That's right. Let it go for Brian Green and the returning champion Brian Green. Oh, thank you. Thank you. Fan favorite. By the way, you know that, right? Appreciate it. Our fans love you. That's great to hear. We love you because you're a theoretical physicist. Yeah. And while of course data matter.

people like just thinking in an unfettered way about what could be true or not true about the universe. And there's so many things being bandied about lately, especially in the quantum realm, that we thought we'd bring you in for a special recording where there are no time limits on this. We're just gonna talk universe.

everything cool, weird and wacky about the universe. Let's do it. And you're the man for it. By the way, when you're not here, I just sort of fumble over how I what I know, but when you're here We got'em. Yep. Exactly. Okay. So let's remind people, you your specialty, I mean, historically is is particle physics. Specifically? Yeah, I certainly can for the particle physics side. Quantum mechanics.

And then moving toward gravity, which of course is the other end of the spectrum. Okay. And that's what took me to string theory, which is this attempt to put them both together. Put them all together. We'll get there. All right, so that means there's no scale of physics that's out of your reach. Well I wouldn't quite go that far. But you are kind of covering it all I'm just saying. What else is left?

are the complicated things. Ooh. Like the brain, like the mind, like consciousness, like biology. You know, so yeah. Okay. We stay simple. You do the easy stuff. The physics is the easy stuff. You've written multiple best selling books. Yeah, a lot. And the one people remember most perhaps was The Elegant Universe. Was that your first? That was my first. That was your first book. And it was a runaway bestseller. Yeah. Yeah. For W. W. Norton. And your most recent book in twenty twenty.

Came out just in time for COVID. Util the end of time. Wow, that's very pr very pre very prison of you. If you were religious would be the end of days, right? The end of days.

Uh so what I like about you is you have a a breezy way with communicating your complex physics thoughts. And in no small measure is that honed in books that are written for the public. A. B. You're co-founder, I think with your wife, Tracy Day. uh former news correspondent who interviewed me many years ago. I think for uh N B C could well A B C A B C yeah yeah yeah and uh Tracy Day co founded the World Science Festival. Oh wow we did. Yeah. Now that's just initially it's just

Being badass'cause it was New York. Which is the world though. I'm not sure if you realize this. So I haven't attended as many of these as I have always wanted, but those have I attended I Thoroughly enjoyed the juxtaposition of the science and the art. And the music and just Science is culture. Yeah, I mean that's the point. I mean much of what your work is about the same thing. People need to see science as part of the fabric. of culture as opposed to something off there on the side that you

are forced to take in school and then you leave it at the end. Right, right. You leave it behind. And so I think World Science Festival does that brilliantly. So I just wanna congratulate you on that year in and year out. It's still going strong. Yep, yep. So before we get to cosmo queries. Because we we poll our our fan base, our our donors really, the Patreon members. And like they all know you. So they're coming in with questions hot and heavy, straight in.

And I I worry that I might be asking some questions that they'd be asking. Is that allowed? Yeah. So what? Okay. And for everyone that we come across that you have asked that they m will ask,'cause they're already submitted. You will just give us five dollars. At the at the entry level, you can't. Yeah. Okay. So Brian, let's let's just right off the bat, we hear about the multiverse. Okay?

on one side of a fence. And then you cross the other side of the fence, and then we hear about the many worlds hypothesis in quantum physics. Do these have anything to do with each other? Yeah, they do. The idea of a multiverse is the umbrella concept. For any variation on the theme where our world is not the entirety of reality. Oh, so that would cover all cases. All cases. Oh. Whether it's the multiverse or not. Yeah. So the multiverse is under

The many worlds. Well I say many worlds is under the multiverse? Okay, so the multiverse encompasses Every single there's something like ten versions of many worlds that have emerged from radically different ideas and quantum mechanics is simply one of those. Okay, so I was mistaken to think. Dare I say traditional multiverse.

descriptions. There's one where there's multiple bubbles within our space time. Sure, that's the inflationary multiverse. I'm bringing it down by the way. Inflation. You're bringing it down Affordability. That's right. Not really in play, it's it's the best price it's ever been He's never been a So and then when I and I learned many worlds when I first learned quantum physics where you needed some way

To get out of the conundrum that you're observing statistical phenomena. Yes, exactly. So so catch us up on the many worlds specifically, and then tell us how that plugs into the multiverse.

Yeah, so when people develop quantum mechanics, this is now going back to the nineteen twenties and nineteen thirties. Centennial decade of quantum physics. Precisely. Which is why I'm writing a book on it. That will be published in this decade. But uh Uh to catch people up on that. Yeah, yeah, exactly. Yeah, very good. And and the and the the progression of the ideas beginning in the nineteen twenties.

was to note that a particle, let me be specific, like an electron, it could be partly here and partly there, you know, fifty percent here and fifty percent there. And the question was, but when you look and you measure, you always find the electron here or there. You never find it in a blended mixture being at two locations. Okay. And people scratch their head for a long time trying to figure out what wha how do we transition? From a theory that describes a fuzzy haze of possibilities to

to the single definite reality when we make an observation or an experiment. How much of that definite reality was a bias coming out of classical physics? Well, you could say all of it. Because our brains are big and we think they probably operate according to laws that are biased toward the classical, the big stuff. Yeah. And our experience. There's an object, it drops, there's a

thing, you move it. Right. There's just stuff that kind of makes sense to us. Yes. Exactly. And nothing in quantum physics makes sense. And nothing in experience suggests there's anything but one single definite reality. And that was a conundrum. Experience shows one reality. Quantum mechanics speaks of

Many possibilities. Measurements in that realm. Right. That's right. So measurements in the realm of the small somehow seemed to pick out one singular definite reality. But here's the problem. When you looked at the mathematics. Which comes from Irving Schrdinger. You can't Transition. They should have Schrdinger's cat in the in the Broadway musical, I think. Cat? Yeah. That would have been really cool. Well, have you been there? How do you know there wasn't?

And this is the point. So Schrdinger's mathematics forbids a transition from many possibilities to the single definite outcome of experience. And so people said maybe the transition never happened. And this is Hugh Everett, nineteen fifty seven at Princeton. He looks at the equations and says we are imposing a classical bias on reality. We think there's a single definite reality, but according to the math, if you look at that cat

There's one universe in which the cat's alive and you see it alive and you're happy. There's another universe where you see the cat dead and you're chagrined. Right. And that's the true reality. Neither of you knows about the other version of you.

thinks they live in a single definite reality, but the bigger picture embraces more than one world. Was that other world always there? Or d was it created in the moment that they have the the realization of another library debt. Right. I it's a really good and subtle question and I don't think every physicist sitting in this chair would give you the same answer. As I look at the mathematics, I would say

All those worlds, in a sense, are there. There's nothing really splitting, which is how we often describe it. The world splits into two. It's more that the description of the quantum realm allows. See the body language. Let me see some of that more? I love that. Give me some more of that.

It i the mathematical description now allows us to use the language of one world or another when that language wouldn't have been applicable before your measurement. But it's not like the world splits and splits and splits. It's all Sitting there in some giant Uber realm. Gotcha. So does the realization of the measurement? Th are you saying that there's a possibility that you're not measuring a definite thing at that moment or instant, I'll call it, in that instant?

Or are you just seeing that and everything else is just still there? But like you can't see it because you're looking at this. See, it all depends on what you mean by you. And I hate to be so specific in the wording, because if by you you have the conventional notion of a single human being Version of me Does see a single world, carries out a single measurement. It's just that if you had a God's eye view, which we don't have.

You would see many versions of me with many outcomes. Okay, that is so freaky. But it sounds like you just pulled that out of your ass. I w I I didn't. I assure you. But that's an important point. Let me just emphasize that when Hugh Everett Came up with this idea. It was the most conservative interpretation of the mathematics. Yes, it seems ridiculously uneconomical to have all these worlds, but the math, if you just take it at face value, this is

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اشتركوا في القناة Det kan verka som att det inte går att driva hela samhällen framåt utan fossila bränslan. Läs mer på vattenfall.se. Hey, this is Kevin the Somalier, and I support Star Talk on Patreon. You're listening to Star Talk with Neil deGrasse Tyson.

So let's back up. You and I've chatted, we've hung out socially, and you confided in me that when you were a kid and when you were in school, if you picked a book off the shelf. and there were no equations in it, you immediately put it back. Yep. Who who does that? Okay. A math teacher's favorite kid. That's who does that. Every math teacher's favorite student teacher's pet in the math class. So so you have a math brain. You have a brain wiring where the math

is clear and present to you more so than any words or descriptions that surround it. I don't have a problem with that. You are also dual professor at Columbia in physics and mathematics. What you just told me makes math the preeminent supreme Account of reality because you're saying the math forces it. And I'm asking you: math is our tool. Why should math that you invented, you anybody, humans

Force anything. Why can't I say there's a different idea that's gonna have different math that doesn't lead to that conundrum? So if you asked me that question twenty years ago, I would have given you one answer, which would have been very combative. And I would have been defending mathematics as like the deep truth of the world. In the past twenty years I've shifted closer to your perspective. I really do see math as a powerful tool for describing the external world.

I don't see it necessarily as the truth of what's out there, which is why I don't support the many worlds interpretation of quantum mechanics the way some of my colleagues do. I allow for it. It could be true. It's interesting. It blows your mind. But I do not say it's true because it comes out of the equations. Thank you. Okay. Okay. That's a

Very um I'll say mature and advanced. That's right. That that's a mature and mature stance. You have matured in the past. Because I don't Uh you know, I love me some math, don't get me wrong, not as much as you do, but when I look at Kepler, who was a mathematician fundamentally and he knew about the platonic solids. Do you know about the platonic solids? I know that they're friends. Platonic friends. Yeah. So you can if you have polygons, uh which are flat

shapes that have the same sides on them. So a triangle would be a polygon. A regular polygon. A triangle, a square, uh a hexagon, that sort of thing. Right. So if you ask, can you make solid objects with these as its sides? Right. There's only five. Five poly five shapes that do that. Five shapes. That do exactly that. Where each side is the same polygon. Okay. Only five. Right. And one of the things that I'm going to do. One's a pyramid, definitely. One's a soccer ball.

Uh no, so has two different kinds of shapes on it. Oh really? Yes it does. Oh so they're not all the same? No and I'll che check next time. All right. Uh but it is a way to tile them to sphere so that you can do it. So one is a pyramid, another one is a cube. Yes. And then there's like three others given to me. And there's another one. Okay, so now Kepler, a mathematician, said There must be some divine reason for this. There's five other and we have six planets.

There was Mercury, Venus, Earth, Mars, Jupiter and Saturn. So he said, wait a minute, if the universe is is is special and math is special, obviously, they have to be connected. They must be connected. So he embedded these platonic uh shapes. إِنْ إِنْ إِنْ إِنْ إِنْ إِنْ Circumscribing one around the other to see if that gave him the orbital distances of those six planets. Because if you have six planets, you have five separations.

between them. He thought that was a major thing. So he's he spends ten years doing this. And it was like and then it was over, he was like, I've wasted my life. Oh God, what have I done? But the math is what took him there. Yeah. Right. The beauty of the math. Yep. And so that was my lesson.

That I you know, I ain't going there. But it goes the other way too, right? Really? Because you go back to say George Lemaitre. So he's a priest, a Belgian priest. Yeah. He's studying Einstein's mathematics, finds that the equations, the math. says that the universe should be expanding or contracting. He goes to Einstein and Einstein says your calculations are correct, but your physics is abominable.

This math is not relevant to the world. It's like the platonic solids. You're wasting your time, and yet, in this case, Einstein was wrong. Oh. Einstein's math was relevant in the way that George Lamache was suggesting the universe is expanding. And it is. So you have to go. Einstein didn't even know his math was relevant. Yeah. So yeah, they would so so Lemotrec He used Calculations of Einstein's equations.

force upon him a feature of the universe that not even Einstein was imagining. Exactly right. Right. So that's meth being bad. The math discovered that. Math discovered it. Yeah. So it's all just to say that it has to be case by case. You got me. Got you.

You got you got me there. Okay. So now if everybody's doing these quantum physics experiments all over Earth and in all alien planets. Is this a countable number of worlds? Yeah, that's a tough, tough question. infinite in any reckoning, but exactly which kind of infinity. We kind of understand it because we don't want to go into the deep mathematics, but there's a whole structure due to David Hilbert, a mathematician. who actually raced Einstein to the finish line in general relativity.

Did not know he was on the on the track. Yes, in fact, he published general relativity a little bit before Einstein did. Oh is a little known fact. Well that must hurt what's his name again? His name is David Hilbert. Damn and and the thing that's called Hilbert'cause it's Hilbert Space Space. Tell me about that in a minute. Okay. But in this particular story, Einstein had visited Hilbert in June of nineteen fifteen.

showed him everything that he'd worked out for ten years Then Hilbert took it the final step and published before him. In the end of the day, Hilbert said, No, no, it's your theory. It's your theory, Albert. But he did publish a little bit beforehand. He would not have published had Einstein not visited him. Yeah, he wouldn't have known anything about the other. But the point for quantum mechanics is that there is this thing that you made reference to, Hilbert Space.

which is the mathematical structure within which all these worlds live. And we understand the math of that pretty well. So why does it need a mathematical structure in which they live? If you're gonna describe things with rigor mathematically, you've gotta define things. You've gotta have the operations. You have to be able to categorize the ingredients.

And remarkably this space that Hilbert introduced has just the right mathematical properties to be the space in which all these worlds live. Does it suffer from an incompleteness? Feature. So so so yeah, so Girdle had a very powerful result. that any basically sufficiently complex mathematical structure will have true statements that can't be proven true within

the axioms of that structure itself. So it just has to be asserted. It has to be asserted or you have to somehow intuitive or feel it or in you know in the general relativity. Are there interesting physical features of the world that would be undecidable in this Gordelian sense? That's what I'm asking you. So is there a feature of general relativity where you you part the curtains enough? There's just some assumption you had to make. Yeah. And everything issues forth from that.

y that you cannot deduce from anything that follows. Yeah, I mean there certainly are axioms within these theories for sure, but are there then deductions that are true but can't be proven within the structure itself? I don't know because when you look at Girdle's proof, the kinds of things that are undecidable are very contrived.

You know, with things like, you know, the set of all sets that are not subsets of themselves. You're like, well, does that ever come up in the re in the real world? You know, or the barber of Seville, you know. So nobody shaves themselves, but then like who shaves the barber? Who's you know? So they're all very self referential, and it's not obvious.

that they have direct relevance to things that we could measure. But it's still an important discovery. Hugely made it. Hugely important. And this thing about the bar the closest I got to that barber question was I I used to read brain teaser books when I was a kid. Okay. And So one of them is you come to a town and only two barbers. Yeah. And one of them's just completely messy and the guy's unkept and these guys And his hair all the Tom looks amazing. Uh he's clean shaven he's he's

But everything's neat, so which barber do you go to? I'm going to the messy one'cause he clearly does the other barber. Exactly. Exactly. Somebody cuts the dude. That's the guy. That's the closest I've gotten to the barber.

So with the many worlds. Now connect that up. to a multiverse. Yes. Which is just a declaration. It's a multiverse of a kind. It's one flavor. of multiverse that comes directly from the math of quantum mechanics. And the natural next question is

Can you prove it? Can you demonstrate it? Yeah, no, I understand that feeling because our consciousness feels singular and this theory is saying there are many individuals in this larger realm that have your memories, that have your experiences, and they only differ from you that they saw the cat dead and you saw the cat alive. Well how to react to this. Give me a second to like just

Tear up. See, I watch a lot of Rick and Morty, so it doesn't bother me. It doesn't bother me at all. I'm just like, of course it works that way. Duh. Uh but this other me That's me identically except we observe the different outcome of the experiment. Yeah, and then from there you continue to diverge because we know that little changes right now over time can turn into major deviations in your lives later on.

'Cause I've seen uh in several films, but let me pick one in specifically, uh HTL's uh the time machine. I'm referencing I didn't read the the novel, but I saw the movie, when is it from the sixties. And the guy, the main protagonist, befriends a woman who shortly after they have this encounter. She's like hit by a truck. Mm. And he says, Well I have a time machine. I can go back and It says, Oh, don't exit the part this way, go the other way.

She goes the other way and something else hits her and she dies. And the safe drops on her head. And so after two or three iterations of this, or in another one she's mugged and killed. Yeah. He concludes that it was just her time and he can't change Fate. Cancer is the outcome. Okay. But when I saw that, I said the molecules of air that are around her are in a different place. Cause she's displacing these molecules relative to these. That's a different universe. Yep.

I'm not gonna look at these as just this is the only thing that has to stay constant. Tell me about all the other little things that change relative to the big thing that you notice. Yeah. So in that version, I think you're right. You know, if the person could really go back in time, change things. I think you would get a different universe. I I don't know of any Uber law that says certain major events or minor events have to be preserved. But in the quantum mechanical version it

completely different. If you take on board this idea, you are committing to different worlds where things are radically different. If they are allowed, if these outcomes are compatible with the laws of physics, then they will happen in one or more of the worlds in the quantum mechanical multiverse. Wow. All, all things compatible with the laws of physics are realized. Wow.

That's pretty wild, man. Okay, so so but all right. I love that though. W wait, wait. Stop. I love that. Here's the only thing that I can't get with that. All right. In that case How do you reconcile infinity or an inf an infinite number of worlds? Let me get there. So what?

We went from the many worlds hypotheses where it is exactly me, but I'd look at a dead cat instead of a live cat, or vice versa. In the multiverses to which I've grown accustomed, there's possibly an infinite number of them, but maybe in one of them I'm there mostly myself, except I have a goatee, or I'm evil Neil instead of friendly Neil. So that's not the world's Neil. You're Neil who believes in tarot cards.

Well, so that's that's that's not a many worlds needle. That's just another statistically configured NEL out of the random molecules in that universe. Aaron Ross Powell Right. But the beautiful thing about the quantum mechanical multiverse is that When you Study the possible worlds that can emerge.

They embrace effectively anything that would have a non zero chance of occurring. Okay. And that's anything in effect that's allowed by the laws of physics. So if the laws of physics allow you to have a goatee, then there will be a world in the many worlds where you do have a goatee. Right. But in in that world, that's a different me looking at the cat. Because the the dead cat, live cat version of me, they each have a goatee.

Uh yes. So if it's a very minor event like doing a single observation. Usually a single observation can't yield such a radical change immediately. It'll be you without a goatee in one, you without a goatee in another. But then if you wait long enough and you accumulate The huge number of ways that you could have gone left, you could have gone right, you could have gone up, you could have said yes, you could have said no. When you put all of those possible different words.

Came along for the ride in that particular world. So here's what I wanna know. Back to the infinity. Yeah. Are there a finite number of particles in this universe? There are finite number of particles in the observable universe. But the universe could go on and that that that's the horizon. We don't know.

Then that means there's a finite combination of all these particles that could create these worlds. And so how do you get to infinity? But if the universe goes on and on and on, then yeah. Yeah. Yeah, there is no end. But even with an infinite number of universes with the same number of particles. You just configure them and keep reconfiguring. You can't because it's not reusing the same electron or the same proton in one world and another. Okay. Right.

And and that's so like a conservation of particle numbers. So I used to be into I used to be into big numbers. I still am, but I've haven't stayed with it. And one of my favorite big numbers I don't know Skew's number. He's ten to the ten to the ten to the thirty fourth power. Okay. And if you if you play that out, you get the total number of configurations.

of all the particles in the observable universe. Right. So it's as though if the universe were a cosmic chessboard, it'd be the total number of possible moves. Right.'Cause you're not counting objects at this point. You're counting events. You're counting things. Yes. Combinations. C combinations. Yeah, I would I would get a different number if I was to use the entropy of the observable universe, which we can calculate from the dark energy. I would get a ten to the ten to the hundred and twenty.

So, yeah. Yeah, so I think it has to do with whether you're only looking at material particles that yeah versus the energy that's the same thing. Oh no, of course. Yeah, the energy is all in there too. Yep, yep. Yeah, this is just counting up the Yeah. Sure. That makes sense. Okay. Cool. So do we do we actually know the amount of of dark energy that's in the universe? Well we measure it. We do measure it. We do measure it by the rate at which we're going to be able to do

And it's this ridiculously small number in the units that we typically use to measure these things. And that translates into this particular number for the entropy, the number of states that the universe can possibly be found in. Right. Okay. That makes sense. But the question you asked before, if we could return it for a second, because it is issue. This issue of

infinite number of worlds. I just wanna remind people that when you say if there's a chance something can happen, no matter how small, you multiply that very small number by n infinity. And you get a you get a real number. You and you get many worlds. You get many worlds in which that could ru that small probability thing could happen. Exactly. So the the infinity that you're where you're about to go helps bring out of the out of the depth.

the statistically unlikely possibilities. And that to me is the Achilles heel or a potential Achilles heel of this approach. And again, I have to say different people in this chair, they will say different things. But the issue that many of us have taken with the many worlds is just that. If an outcome has very small probability, right, that should mean it's very unlikely to happen. But from the analysis that you just gave. No matter how unlikely it is to happen, it will be realized in the

So what does it mean to say something is unlikely if you're sure it's gonna happen in some world? Exactly. This is in astrophysics where we talk about supernovae. as being an extremely rare event. Uh-huh. Okay. Not all stars will go supernova and even high mass stars, some go black hole. Right. It's rare. Right. However The galaxy has a hundred billion stars in it. There's a hundred billion galaxies in the universe. So when people realize if you have enough of a sample size.

You could deliver every single night. Supernova into your catalogue. Right. It's a rare event that happens often. Exactly. So th that was that was initially s kinda hard to explain to the public. Yeah. How how you get that. Yeah, so we have a version of that in the quantum mechanical multiverse, but it is more of an issue.

Because you're guaranteeing the existence of a world, a whole world filled with observers and experimenters who are guaranteed to see the most unlikely things on a regular basis. Right. And and that is an issue. Now there are some people who work on this who say, We've solved that. Just read our paper, read our book and they do some interesting mathematics. I am not convinced. And that to me is where the issue is. Okay. Interesting. So let me ask.

We chatted about this over lunch a a few moons back. Oh it's in your inbox. Brian Cox. So I'm Sureya. Yeah. Forgive me if'cause you're my favorite physicists out there. So but so d do you feel bad that I have another physicist who I a little bad by it is all right. So

I happened I learned this early because I said I was into big numbers when I was a kid, that there are levels of infinity. Yeah. I think they're at least five. You can keep on going. You buried the lead, guys.

Now you gotta explain that. You can't just say that. You weren't at the lunch, so should I that there are levels of infinity? Yeah, yeah, yeah, yeah. But you weren't at the lunch. Do you know how counterintuitive that is? You weren't at the lunch. So should d do I have to drag you behind us in the

I know man. Well we'll get we'll explain that in a minute. All right, go ahead. So I kept thinking to myself that You can have an infinity of universes and that would not be an a big enough infinity to exactly reproduce me. And that you would n maybe need it higher levels of infinity. to get all the combinations that people like to talk about in the multiverse. Right, right.

So does it does it require the higher levels of infinity? You know, the the the most straightforward answer would be to say I don't fully know it because I don't know that science understands you and by you I mean life well enough. You know what he just said? He said I could be so simple it's trivial to copyright. But but but if you take on board the idea

that you are just a collection of particles that are governed by the quantum mechanical laws. If that is something you're willing to accept, then there is enough room inside of, you know, Hilbert space and the quantum mechanical infinity to reproduce you and to reproduce Every variation on you where some of your part of every variation conceivable. Yes. Yes.

Every variation allowed by the quantum laws, which simply has a tooth cavity because I've never had a cavity. If that's compatible with the laws of physics, and I think it is, then yes. So non dental plan Neil. This is the NEO with no dental plan. Then

We got enough we got enough ma not matter. We have enough material to make sure that that happens. I don't need the higher levels of infinity to get there. Okay, so now let's let's catch up, Chuck, because everyone else out there knows about multiple infinities. Uh so Please catch me up. So these are levels of infinity. I think there's a Hebrew letter associated Aleph. Aleph Aleph. Aleph Zero. Uh-huh. There's a traditional infinity. Aleph one, two, three. So

We don't have to do all five. Just get me to like the second infinity. Yeah. So the simplest one is the one that comes to mind immediately. You just count the numbers. One, two, three. And they just go on. And they just go on. And that's the simplest straightforward. But then if I ask you

How many numbers are there between zero and one on the number line? Oh wow. Now you say to yourself, well, can I enumerate them? Can I put them into a correspondence with the counting numbers and just list them? However, but am I am I not go but I'm still going towards infinity.

Aren't I dividing then when I go in between numbers? Yes. I'm kinda dividing. You are and you could say, well, let me put a dot in the midpoint, call that one, and then a dot in the midpoint between it and zero and call that two. You won't cover all the numbers. And and there was a wonderful It'll never reach one.

'Cause there'll always be a place where I can once again put something in between one and where I am. It's another way of saying it, but Cantor had a powerful argument that's actually pretty easy to understand. Uh we'd need to write it out for me to show it to you. But he established that if you try to enumerate the numbers between zero and one, just list them, you will fail. You will always miss some.

And therefore there are more than an infinity of numbers between zero and one. And that next level of infinity is the version that Neil was referring to. Alice Wahl. Yeah. Alice, give me my bag. I'm gonna need my weed. Okay. So you just skipped by it and I wanna make sure we can contemplate it briefly. The one way to know which infinity is bigger than the other is you correspond them to each other. Yes, exactly. Right. So you can say, because this is kind of a little freaky, the odd numbers

Is the same size infinity as all the counting numbers that include odd and even numbers. Of course. Now how do you how do you get that? Well, you know, you could take any given number and say multiply it by two and add one to it. Mm-hmm. And in that way you're You get an odd number and now you've lined up you've lined up the numbers one, two, three, upward and the list that it corresponds to are all odd numbers. They all just go up. Yeah. Damn, that's wild.

Wow, math is kind of cool. Who knew? Okay. And and just just to just to taste it, uh if I remember correctly, I left Two, does it go into another dimension? The number of lines in three-dimensional space. is a bigger infinity than the n counting numbers on a number one. Yeah, that may be a way of saying it. I'm not sure. There are many ways of expressing these infinities and there's actually a kind of an uh almost an algorithm

That allows you to start to build up this set of infinities. You can look at subsets of subsets and things of that sort. Look at power sets as it's called. And so it's a Стоундли стран ідея. Which is why mathematicians who thought about this in the early days. You're all in asylums right now. I'll never get to one. I'll never get to one. I'll never get to one. I'll never get to one.

So and if you go to higher dimensions, in principle, does that take you to not necessarily infinities? No, I mean if you start to look at the number of points in the plane it you know.

Points of a line versus points of a plane. So you have to be fairly sophisticated in how you build up these infinities. For our purpose, there is this thing that we've made reference to, it's a bit abstract, this thing called Hilbert space. And we understand it reasonably well. It's an infinite dimensional space. that David Helbert developed, but we understand it well enough to say it does have enough room

to embrace all the quantum mechanical states. And and within that space, in principle, there is a place That describes you. All right, so now I am however improbable in the configuration of atoms and molecules. Even here. In this actual reality. Okay. So have you th thought much about Whether or not something can exist and whether or not it does.

by which you came to be. And I'm saying let's go to your childhood, to your birth, let's keep on going further back, your grandparents' grade let's go all the way back to the Big Bang. And if you look at the sequence of steps from the big bank go back to the big bank you do actually, right? That's how we get here. You know, we we we we we have collections of particles that are configured in a certain way.

And they have a history. And it's that history which resulted in them being in the configuration that's called Neil deGrasse Tyson. And if you look at the sequence of quantum steps, each of them are incredibly unlikely in the collection of those sequences. is innumerably

Huge and therefore incredibly unlikely and yet here each of us are. So what do I do with this information? Well, I think it gives you a special special. Well, uh you know, there's uh y y if you want me to be a little bit sappy, yeah. You know, I think it inspires a gratitude. The unlikel of us being here against of of being at all. And therefore is a certain kind of thankfulness that the universe.

Turned out in a way that gave us a brief moment to stand up, look around, and appreciate everything. That's wild. So now I'm looking at that and immediately going back to our previous conversation about the two observers. Okay. With the dead cat live cat. Live cat. And the m and the mini world. What you just said. can negate that, meaning that also there are an infinite number of worlds

Where there's just no Neil. And then there's an infinite number of worlds where there is no cat. And then there's an infinite number you you know You're absolutely right. And I think that's one of the lessons if you take the many worlds approach to quantum mechanics to heart.

It is saying that clearly we are compatible with the laws of physics because we're here existence proof. Right. And if you take the many worlds seriously, then we were guaranteed to live in some world in this grand collection of many worlds. Now In some sense, this world is incredibly unlikely within the panoply of possibilities. But you're right, in that sense, we were

An inevitable outcome of the quantum law is because we are allowed by those very laws of physics. Right. But Brian, I I have a more anchored version of what you just said that I that I credit to Richard Dawkins. Yeah. If you look at the total possible genetic combat nations. Mm-hmm. that will make a human being, a viable human being. Okay. It's a stupefyingly large number. Like like four to the three billion or something, right? Right.

Yeah. What matters is not even how big it is, but it's vastly larger than the total number of people who have never been born. Right. Yeah. Which if plus or minus, it's about a hundred billion. Yeah. Okay. So Dawkins' point is We should cherish life because Most people who could ever exist don't will never even be born. That's right. Yeah. Yeah. So we can be sad that you die.

But he describes those people who die as the lucky ones who got to live in the first place because you can only die if you got to live. Right. And for me that's a little more anchored than than Yeah, but to take the point we were saying before, if the multiverse version of quantum mechanics is the right way of thinking about it. They did then they did live if their genetic sequence was compatible with the law of the physics. So don't feel bad.

Yeah, for all those little swimmers that didn't quite make it to the egg.

The sperm you're talking about? Yes, exactly. So Brian, I get this question off and surely you do as well. If we live in a multiverse and we're just one of an infinitude, where are the other universes? Yeah. And you're gonna cop out and say, oh, they're in the infinite dimensional Hilbert space?

Well, It's easier to answer that c question for other flavors of multiverse like the inflationary multiverse that you made reference to before because That's the simplest that's the simplest one to give it that one. Yeah. Right. And there's another bubble over there in the same Sort of space. In the same construct. Construct. In the same construct. Yeah, because according to inflationary cosmology, as you're making reference to, there was an energy field that gave rise to repulsive gravity.

that drove our big bang, but the math shows that it would not have used up all of that energy in the process and would be left over. The leftover energy would yield another big bang and it would not be fully used up. Yielding another big bang. And so these distinct big bangs, as you say, would give rise to these sort of bubbles in a big cosmic bubble bag. Okay, so that's in one construct. Yeah. Okay, but now There are other variants uh multiverses.

where it's sort of separate. Yeah. When you when you talk about the quantum mechanical multiverse, it's much harder to think about where those other worlds are. They're not kind of adjacent to our space. It's a more abstract place that they inhabit. And I'm gonna try to avoid using the word Hilbert space, but that's the mathematical architecture within which we can see these worlds existing.

I can't picture I can't picture where these other worlds are. If you ask me, do I have a mental image of them? Not really. Okay, so that's a mathematical architecture. Can I divine an experiment that would Show that they exist? Is it can I wormhole to them? Yeah. Do I even want to wormhole to them? Because quantum physics might give you slightly different laws of physics.

It's unlikely that the laws of physics are different, but the properties of ingredients might be different in principle if there are sufficient quantum mechanical processes that could yield worlds with those distinctions. But I don't know of an experiment, and I don't think anybody does. Where when you can say if we could get this and this result, we would establish that the multiverse is true. Yes. So that's another variation on the multiverse that comes from string theory.

Which we can talk about we might talk about, in this version, our universe is sort of like one piece of bread in a big cosmic loaf.

And the other slices of bread would be the other universes. So they would really be hovering next to us, just displaced in an actual additional dimension of space. And then you're right, gravity can influence, permeate that space. So when I was having my little ayahuasca trip, I met these beings that were in-betweeners. And they were in between dimensions. That's where they occupy.

Okay, I feel so silly. But they We're listening. Okay, they explained that they talked to you. They did. They talked to me. And they were two dimensional beings that I could see in 3D. Sounds creepy, but that's the only way I can explain it. Okay. And they explained to think of it like an infinite number, and they call them dimensions going out. And going up. And going out. But to think of them

as a deck of cards slapped up the way we see a deck of cards, we see it as one deck of cards, but it's not. It's however many cards are in that deck. Right. And until you separate them, that's when you can see the different things. That's how it was explained to me. So this is almost the reverse of that. It's as if we only see one card in the deck. That's our world. Right.

But a God's eye view would see the entire deck which would have the other cards. And that's who that's where they see. But anyway, I'm just I I had I had shared that with Jana Levin and she was like, that's pretty interesting because and then she gave me some speak that I didn't understand. Yeah, it must be the same basic idea. Actually we just wrote a paper on these so-called brain worlds in in string theory.

So this is short for membrane. Membrane. Yeah. Sorry. So these ideas, these are universes that are like a membrane and there can be multiple membranes, which would be multiple worlds. Right. And in principle, as Neil was mentioning, they can influence each other. Gravity from one can influence things in the other. So I never took I'm saddened by this. In graduate school I'm taking astrophysics classes.

But I wanted to take more physics and a physics class I never took was field theory. Yeah. A a whole course on field theory. And you can come to my class. One of these yeah I've taught field theory a number of times. Yeah, I'll let you know next. Oh boy, that's not intimidating. No, but I I w I'm not in a position to calculate or even really know why gravity can escape, but not the electromagnetic. Well, I could give you a quick mnemonic sort of to think about that, which is so in string theory,

Gravity is communicated by a string that has no ends. It's a closed loop. Okay. The electromagnetic force is communicated by photons, which in string theory are strings that have two open ends, and those ends are anchored to the membrane. They can't escape the membrane, but because the gravity particle, the graviton, has no ends, just a loop, it's not anchored. It can get off and travel between those worlds. Is that a description that would be in the book?

String theory for dummies. It's there, no doubt. Okay. So if that's the case, why isn't what we measure as dark matter just gravity leakage from a another slice of bread? like that. If your s dark matter is meant to explain the gravity that we know is there but dark gravity is dark gravity. Yeah. So if you can have some source of gravity that you don't literally see, it's a candidate.

And so people have put forward it's hard to make this idea really work, but in terms of its general possibility, sure. Because the betting person's you know, if you're if you're into betting what an outcome would be. An exotic particle is sort of the the betting man's solution to the and but that's that's put forth by particle physicists. Right. You know, if you're a hammer, you're a little bit biased, right? A little bit of bias, right? Right.

So I'm liking me the you know, this gravity spillage. No, I like the idea. It's in detail it's only when you get down to brass tacks that it's hard to make this really work. All right, so let's pick up the baton here.

on strength theory. Yeah. Okay. Where I'm a little older than you, but we we came of age with enough overlap. So I can speak of the nineteen eighties as a time where strength theory was birthed And started taking off with some vigor. Yeah. All right. Everybody I spoke to at the time. And at the time I was at the University of Texas, which had its share of strength theorists. Yes. And and Steve Weinberg was a very good thing. Steve Weinberg for sure.

A graduate of my high school. That's true. That's true. Not your high school. Yeah, I agree. So Steve Weinberg, uh a Nobel laureate in physics, uh cosmologist, you know, all the back. Anyhow, so I asked people So when you guys gonna figure this out? Because you're trying to unify quantum physics and and the large and the small. And it's oh, we're almost there five years. In five years we think we'll do it.

So, you know, ten years later. Well, when are you gonna do it? Oh, in five years twenty years later. Oh, in five years the problem is hard. It's a hard problem, but we're on the t and so I I've never heard convergence in any conversation about strength f theory landing where it had intended. Yeah. A. B, could it be, and I think I've said this on stage to you, and you didn't jump up and try to hurt me. Could it be that all of you are just

Too stupid to figure out the solution. And you're let me say that more charitably. Are we awaiting the birth of some twenty-first century Einstein to see the solution here that none of the rest of you are? Yeah, yeah, it's all possible. First off,

I would never have said five years back then. It's a very dangerous thing to make a prognostication of that sort of thing. Yeah, it was i there was huge enthusiasm. But look String theory has done miraculous things since the 1980s, and I'm happy to sort of list. the achievements, but you're right. It's not done the one thing that ultimately matters, which is make a prediction that we can test, you know, at a particle collater and determine whether these ideas are correct. And it could well be.

that we just don't have the brain power to get there. And it may not be that we're awaiting the birth of the next Einstein. Maybe we're just awaiting the next configuration of AI that may be able to do what we as individuals have not been able to do. I do think there's a real possibility of the nature of research changing in the next five to ten years. I did hear that. Because you know the uh I give you an example.

I mentioned this paper that I wrote with Jana Levin that you make reference to. Mhm. Is this the the loaf of bread paper? No, it's a sl we wrote a handful of papers together. This is a more recent one. And I wondered could chat get the answer that took us a long time to get? If I treat the Chat GPT, if I

treated it as sort of a good graduate student. Uhhuh. So I just gave it a few prompts the way you would to a graduate student. Did not give it the answer and it couldn't look up the answer. We hadn't yet published the paper. And within a half an hour, it was able to reproduce the results that took us months. Oh my gosh. And so it's as if you have the greatest graduate student known to humankind, even an army of them. At your disposal. And that's now. This is a hologram right now. It's an Avenue.

So what is it going to be like in five years? You know, it's it's both exciting and scary. It's a good thing. I have a colleague who has a similar story regarding his research where he was prompting chat. to think about a problem and it solved a problem that he could he had not been able to solve. And actually solved it. Yeah, actually solved it. Wow. You prompt a really good graduate student in just the way you're describing. Right. But catch us up

Just on why the whole field is called string theory? Well, the basic ingredient is a filament that looks like a tiny piece of string. The idea is that it can vibrate in different patterns. And the different particles that we know and love, electrons, quarks, neutrinos and so forth. Fundamental particles would each correspond to different vibrational patterns

Of this new entity called the string. So the string becomes the fundamental particle. Yes. And it's a unity because it's one thing that can manifest as many different things. depending on how it's vibrating. Which is for people who like unity, this is a be this is a beautiful thing. It's a beautiful thing and it goes even further. When you look at the math of this, you find that not only does it unify all the particles

But it unifies quantum mechanics and general relativity. The laws of the small and the laws of the biggest does it do that for free? It does that for free. It just comes out. I'm telling you, you look at the math. Einstein's equations from general relativity.

embraced that reality of strength theory. So I'm delighted to hear that. So that that was part of the enthusiasm that people would have then had. That was really the heart of it all. The major obstacle is that the theory is Mathematically complex. And the pathway from the fundamental equations to physics we can see in the laboratory is fraught. It's difficult. Tough terrain to cover. And so we've been developing mathematical tools to do that for now thirty years. We've made

Progress on black holes. The eighties was forty years ago. I guess you're right. Oh my God. Strength there hasn't answered that question yet. Yeah. Firty years ago. Forty years ago. Four years before that was the nineteen forties. Yeah. Just to put this in context. I'm with you on that. All right. You know, so we've been f for forty years trying you know. And so we've understood things about space and time and and gravity and black holes. I didn't think we'd ever understand.

On the flip side though, we've not understood the things that I thought we would have understood by now, which would be make a prediction for what's gonna happen at the large hadron collider and let's check it. And so it's an interesting thing that we've made headway on the very things I thought would be too hard. And we've not made headway on the things that I thought we would be able to reach by now. Right. So

I don't like making arguments that other people make just for the sake of bringing the argument to you, but just let me just do that. But let me do it anyway. Let me do it anyway. Uh so string theory has not been without some criticism. Yeah. As something that is consumed the ambitions of graduate students and faculty and promotions. And so it's a field without a prediction that can be tested. yet it had such a presence on the landscape of physics departments that it might have

smothered some other branches of physics that might have been a little more promising. Could you just comment on that? That sounds like jealousy to me. Well It's an interesting argument because the very graduate students and junior faculty and senior faculty who this person who's making this argument fears may have wasted their time not looking at something more promising.

You gotta assume they're really smart people because they're the very people you think who could have pushed the frontier of another field. And if they're that smart, Allow them to make a Yeah, who are you to say that they're not gonna go to the right? They were looking at the ideas that are out there found the string theoretic ideas so compelling that they were willing to take a chance.

And and that chance may not pay off in our lifetime. And tell me about the ten or eleven dimensions. Yeah. Because that sounded very cop-outy. Uh well, it's like I can't explain this. Let me throw in a dimension. Ah, good. But but it's another dimension. Good, good, good. And I think if I articulate this correctly

I think you'll have the same epiphany that you did about gravity coming out of string theory a moment ago. Because again, you wondered, do you have to put general relativity into string theory? I said, no, no, it just comes out for free, which is a beautiful thing. How about the extra dimensions? They come out.

For free too. They're forced upon you by the equation. Not at all. Literally, this is not a joke. There's an equation in string theory that basically looks like D, the number of dimensions, minus 10 times this complicated factor, must be equal to zero for this theory to be self-consistent. The complicated thing is never zero, therefore d minus ten must be zero, therefore d must equal ten. That is where the extra dimensions are forced upon you by the equations.

That's insane. That's pretty cool though. Yeah. And I mean that's So ten dimensions so we don't experience them. Why? Because we believe that they're probably too small for us to see with the naked eye. Or or what small dimension means. It means that if you head off in a given direction, you kinda return to your starting place so quickly. You can think about a straw. Right? A straw has a long dimension. that we can easily see, but has a curled up circular dimension

And if that circle of course we can see that with the naked eye, but if you made that circle liquid through it. Yes, but if you made that circle smaller and smaller and smaller, at some point you won't see it at all and you'll think it's just a line. A line. You've hidden the extra dimension. So all the other dimensions are hidden.

one explanation for why we don't know can anything exist in those hidden dimensions. In fact, I was gonna call the elegant universe hidden dimensions. That was the title I was playing with back you know, twenty five years ago. But anyway, yes, exactly. All right, so you're hiding the dimensions from us. Yes. Okay. But now that is by hand. So when we look at the math, the equations don't tell us these extra dimensions are really tiny.

Instead we're doing what you accuse me of perhaps on other things. We're saying how can we make this theory compatible with what we see? Let's envision that the extra dimensions are really small. Got it. Okay. And so how so a string is ten dimensions? A string is living in a ten dimensional space. Okay. Now, why would a string be fundamental and not because a string is one dimensional. Yeah. And dimensions are just dimensions. Why can't there be another reality?

maybe in which we're embedded with the string is not fundamental but a plane is what's fundamental. Yes, and that's one of the developments in string theory itself. So when we talk about these membranes The piece of bread or the card in the deck. And string theory takes you there. It's not something again that you put in by hand. He goes wherever his equations want to tell you. I need to say this is a purely mathematical undertaking. Totally.

You don't put things in from the outside. You study the equations and it takes decades sometimes, but you extract what the equations are trying to tell you. So before I go to queries. What is the current state of string theory? Current state is health. Yeah. I I you know, it's funny. I asked this question in a program to three string theorists, a World Science Festival program. I asked them, guys, grade

String theory. How you know if string theory was a student, you know, how would you grade it? And the grades went from B plus. I think that may have been uh Nobel laureate David Gross. I I could be getting their grades wrong, to an A plus which was Andy Stromminger, who's a string theorist at Harvard. And if you look at its theoretical insight into black holes.

the mathematical insights that it's given started whole fields of mathematics. If you have any interest in the nature of space and time and what it might be made of, These are the kinds of insights that string theory is giving. So I'd say it's very healthy, but it has not made a prediction allowing us to determine whether it's correct. of a of a viable theory. Yes. And that's why

Maybe you shouldn't call it string theory. Oh, what should we call it? Yeah, maybe call it the string hypothesis. Okay. That's a more humble Yeah. But the math makes it a theory. Well No, no, no. The theory is theory you you For a theory to be a bona fide theory.

It's gotta not only account for what you see, right, or in an organized, coherent way, it's gotta make predictions that you have verified. Right. You gotta be able to you gotta be able to make not predict it, then it's only one half of what's going on and It does it. Got it. But is that because and I don't want to sound like a you know, a jackass, but what you just explained, I I I gotta say, like Einstein had it easy.

I'm I'm serious. Yeah, right. Like Einstein had it easy compared to what you're just talking about. I agree. He wrote down his equations and within a handful of years you could test. Right, because it's like it's here. Right. It's right, it's around us. It's everywhere. Like you're talking about

stuff that is we I mean how do you get to it right we've had problems unsolved problems that have lasted much longer than these forty years in the history of science. Okay. So it took a long time to understand heat. And uh energy. That's very funny what you just said. It took us a very long time to understand heat.

No, we didn't know what it was. The fundamental basis of it. That's hilarious. No, no, we didn't know. Is is it a some fluid fluid caloric? They called it caloric that can flow. Yeah, and so and you know do you know where we did motion? Well no, that's the air looking like the air is a fluid. The air is a fluid, though that's not the heat. But go ahead. Yeah. Were cannons.

Because you'd fire cannons that the the metal gets hot. Yeah. So as it got hotter they weigh it to see if it had more heat. If the heat was a thing. Right. If it was ab if it was Ex uh like possessing. Possessing hits. Exactly. So yeah, so there we went decades and decades with other so maybe I shouldn't be so hard.

on string theory. Yeah, this is a pretty good place to have gotten. Let's wrap it up right here, folks. Thank you. Good night. Okay. And one last thing. I want to hear it again. Just'cause it was so beautiful. All right. So beautiful.

Just tell me speak to me, Bryant. 'Cause it's it's it's sweetness to my ears when I heard you say, I think it was you, that The virtual particles in the vacuum of space coming in and out of existence as predicted by quantum physics, they are quantum entangled. with each other and that quantum entanglement are wormhole. And those wormholes are Representative. The literal

fabric that stitches together the universe itself. Yeah, we were definitely talking about this at some point. Uh no, this is where are we on that? Well it's a beautiful idea. It really beautiful it really comes from Lenny Suscon and Juan Maldissena and a whole

army of string theorists who's developed these ideas. Yeah, he has a wonderful book. Very innovative guy. Yeah, I mean he's driven physics for decades. So So he and Juan Maldusena realize that these quantum entangled particles, which Einstein really in a sense predicted in his EPR paper Einstein, Podolski and Rosen, in nineteen thirty five. Maybe connected to another Einsteinian idea, which he came up with the two months. Distinct from that first paper, an Einstein Rosen paper on wormholes.

That is, two particles that are far apart can have a subtle quantum link. And that quantum link may be nothing but a wormhole yielding a shortcut through the fabric of space that in some sense makes them very close to each other. And those wormholes themselves are what Space time is comprised of. So the substrate of space itself would be wormholes. Yes. That's right. So Mark Von Romsdok, British Columbia, uh Canadian physicist.

realize that these wormholes may be the fiber stitching together the fabric of space itself. Because he could show mathematically, if you cut the quantum entanglement The fabric of space pulverizes, it falls apart because you no longer have the wormholes connecting pieces of space together. That is wild. So I'm gonna keep keep watching that.

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We should have some jingle or something that- Or some animation. Queries. Right. Questions asked by you. if you're a Patreon member Knowing that our guest today is Brian Green, the one and only. So we have a starter question from one of our own. Uh producers. Yeah. Tamson, our producer. Yeah. Our taskmaster. Um Tamson s wants to know this, Brian, if space time Had consciousness of the And could have a favorite movie. What do you think that movie would be?

I think it would be uh Planet of the Apes. Oh that scene at the end, you know, with a half submerged Duncan. You fool your damn house Damn you That's it. Wow. Yeah. Because that played Loosey goosey with space time. Yeah. To go into the future. It's another Earth. And it that's a different evolutionary path. It was the first uh time that time travel really meant something to me as a kid. I was like, Oh man, this is crazy.

Yeah. What's a good one, man? Yeah. Planet of the Earth. The original. The original. Forget about the other seventy five thousand. Return to the place, escape from the place, bride of the planet of the apes. Banality of the planet of the apes. You know what when I went back and saw that film, it's actually quite deep because the the different Species of apes.

had different roleside. Socast is the castle, sure. Right. So the chimpanzees were the academic class. Right. Because they're close why not? Of course. They're our closest cousins. And the baboons were like the police. Right? And the orangutans are the elders. No, no, no, the orangutans were the diplomats. Diplomats, that's right. So the politicians. It was politicians. It was a caste system. Yeah. That's right.

It's pretty wild. So our first few questions have been previous previously asked by our Patreons uh supporters. But you said I'm gonna have to see what Brian says about this. Oh right. So they were elevated. So they were elevated. Okay. It was above my pay grade, right there.

Let me get my supervisor. So this is Brian Burke. He says, hey Dr. Tyson, Lord Nice. Chuck, you should be able to nail this one. It's Brian from Cork Portugal. Brian, shut up. Uh he says, Can you help explain the information paradox with black holes? My understanding is that quantum mechanics and hawking radiation are at odds about this. One says information is forever. The other says information disappears when a black hole evaporates. Are we any closer to understanding how this can be?

Thanks and please keep doing what you're doing. We need real science to carry on, live long and prosper. Ooh, nice. Now let me preface that a little more here. So I was delighted to learn that the evaporation of black holes, the Hawking radiation, is the exact inventory of fundamental particles that went in. even though it's being conjured out of the the gravitational field of the black hole itself, the energy density of the field.

So I say, oh, so that's a a total reckoning of ingredients. But if I went in as a DNA molecule and I come out as the various fundamental particles, the information is that I was DNA is gone. So no, there's no preservation of information there.

And that's what Stephen Hawking said. So when Stephen Hawking did his initial calculations in the nineteen seventies, He came up with this idea that black holes could actually radiate through quantum processes, the production of particles just outside the edge of a black hole, one falls in and the other races away. And the question was, do the particles race away have the information content about everything that fell in, or don't they? He said they don't.

My calculations show it's a thermal bath of particles, a vanilla featureless bath of particles, no information inside of it. We particle physicists said, Come on. Quantum mechanics doesn't allow information to be lost or destroyed. So if you're saying that, you're saying quantum mechanics is wrong. Okay. And we're not willing to go there. Yeah, quantum is so it's so successful.

Right. Okay. Somebody more than Stephen Hawking. And this led Lenny Suskin again and Gerard DeTuft who won the Nobel Prize and various other people to spend twenty five years trying to answer this question. And we believe, largely from string theory, that we do understand that the information does in a very subtle way come out of the black hole. Subtle quantum correlations between the particles that emerge from the black hole do carry all the information of, say, the DNA molecule that fell in.

So you can recover all the information we believe. Now there are still mysteries that we're still figuring out. But just about everybody, including Hawking before he passed away, agrees that we believe the information does come out. Prescoll or John Prescott. Yeah, great. He was a a postdoc when I was a graduate student at the University of Texas. Okay. Yeah. Yeah.

So Prescott won the bet then. So so Prescott won the bet, but Kip Thorne was also part of this. And Kip Thorne was unwilling to concede. Yeah, absolutely. We we interviewed him in his office in Pasadena. So so Hawking conceded the bet that John Prescott said the information does come out. And he gave him an encyclopedia of baseball a lot of information he provided him ha ha as as the way to baseball already has too much information. Now you have an encyclopedia of baseball.

I don't know where Kip Thorne stands on this. I don't know if he has conceded. Okay. Okay. Oh and what what's the business about the information being stored in the event horizon? Have you Yes? Oh that's the what do you call that? That's the the holographic idea. Incredible. Things fall into a black hole and we believe that they leave on the surface.

in some sense a copy, a residue of their information and that's how it can come back out. It never actually goes away. It never went in. The imprint the imprint was left on the event horizon. Yes. Very cool man. Super cool, man. Yeah, so we have an explainer on whether or not we're living in a black hole. Mm-hmm. Just the properties, yeah, which could be If it's big enough, yeah. Okay.

All right, here we go. This is Rachel. Rachel says And we're still in questions and I I had to call my boss. Rachel says, What's up, Dr. T Rachel here from Austin, Texas. I've been thinking about the spinning universe hypothesis.

Which suggests our cosmos might be rotating as a whole. This idea has been proposed as a potential way to resolve the Hubble tension, but it got me wondering. If the universe is indeed spinning, could the force we attribute to dark energy, which is causing the accelerated expansion, actually be explained by a kind of cosmic

centrifical force. So she's thinking that we we just on a whirly whirling dervish whirly Whirling Dervish. We're in the Whirling Dervish. We're we're in a teacup ride. It's hard to say how you'd make that work. When we See the evidence for dark energy. It seems to be so called isotropic. It's the same in every direction in which you look. Whereas if the universe is spinning, there's an axis.

There's an angular momentum that picks out some directions as different from others. That's right. So it's hard to see. So if you look at the water axis, there's no centrifugal force. Yes, but if you look off the axis, we study the motion of distant galaxies, we look across the entire sky. And so we have sufficient data, I think, to rule that possibility out.

But who knows? May write a paper and we'll uh see what we'll figure it out. Yeah, that was all right. What a great question these uh okay. Um we're gonna move into regular questions now. Well, wait, why don't we pull out one that was there and I forgot who asked it and it was about whether we'd have a

Quark catastrophe. So we had a Patreon member write in. The questioner knew that if you have two quarks in some kind of nucleon, then you try to pull them apart. There's a point where that snaps, but you've invested so much energy in it that two new quarks show up in that instant. Now you have two pairs of quarks. Right? We good with that? Yeah. Okay. So in

a black hole or maybe in the big rip, either. Mm-hmm. Let's look, let's look at the you're descending to the to the singularity. The the two quark particle falls Tidal forces get greater and greater, and then it splits the two quarks. So now it become two pairs of quarks as they fall in, then it becomes f four pairs and then eight pairs. And it'll just be this unlimited increase in the number of quarks as it descends to the singularity. Why doesn't that happen?

Well, you you do feel tidal forces as you get ever closer to the center for sure. But I'm not a quark. And and and it's a finite timescale between when you cross the event horizon and you hit the singularity and I c I can well imagine that particle pairs are created in the last moments of this, but whether all of the energy gets transformed in this way, that seems unlikely. You'd have to calculate after I rethought about it, it occurred to me it's pulling that energy out of the black hole.

So it would evaporate the whole world. Oh, if they're thinking that an infinite energy transfer, then yeah, absolutely. Everything is finite timescales, finite energies, and so yeah. Exotic processes can certainly happen when the gravitational force is that powerful. Right. Now of course when you get to the singularity, we have no idea what actually happens.

That's one of the goals that we've not yet achieved. And the big rip would be the same thing. There's a point where the Yeah, that that's true to the expansion if it was sufficiently high. If would get on the scale of Uh nucleons and split apart. The core canter core pairs. And then make another pair and just keep doing it. There are all sorts of ways that energy can transfer from the big rip or the gravitational energy of a black hole into particle production, into various kind of particles.

The entire dark energy universe. Inside you but we're still inside the black hole. No, no, no now we're just looking at the big red I'm just wondering if this keeps happening, yeah, it's using up the energy of But then of course if that were the case it would no longer undergo the accelerated expansion and say

All right, this is Michael de la Morena who says Is time a dimension or a field? It seems more like a field because it can be affected by gravity. That was another one that I punted to Brian. Mm-hmm. Is time a dimension or a field? Well uh I'd say the deep lesson of Einstein was that Space and time. can be affected by their environment. And they in turn create the very environment that then back react reacts on their own shape and structure. And so we usually think about time as

A coordinate, a label telling us when things happen, just like coordinates in space tell us where things happen. And the unexpected thing is. That label, the amount of time between two different locations, can be influenced by the force of gravity. Right. But that doesn't

Require that it be a field. Yes, I doesn't require it be a field. Right. To be influenced by a force. But I understand the intuition because we used to think that the labels, the locations of where and when things happen in a Newtonian perspective They're just inert. They just sit there. They don't do anything. Mhm. Einstein elevated them to be dynamical qualities of the world. And that's the deep lesson. Very cool. All right. Great question, Michael.

All right, this is Cody Rosenberg who says, Hello, doctors and Chuck. I'm Cody Rosenberg from Eugene, Oregon. Please know that y'all are goaded For us armchair astrophysics. physicists enthusi or physics enthusiast. Oh, all right, very nice. Anyway, do you guys think that life is inevitable? Do you think it would be weird for a universe to exist that can't be experienced or observed? Do you think we are the physical manifestations of the universe yearning to experience itself?

So it's a very John Wheeler like way of looking at the world. Wheeler loved to say that we are the way that the universe becomes cognizant of itself. It's a poetic picture. You had a you. With an eyeball. Yeah, yeah. A a U a a serifed U. And on one of the upwards of the U there's an eyeball looking at the other line of the U. So the universe looking at it itself.

So it's uh you know, narcissistic or beautiful depending on your perspective that we're here so the universe can think about itself. I don't know of any law that makes life Inevitable. It seems it was a lot of happenstance between the Big Bang and today. But, you know, we don't understand a lot about the world and maybe one day we'll find there's this law, this inevitability of the existence of galaxies and stars and planets and people, at least on one such planet.

I don't know of any such law. Well let me ask you about this. Well but there's some thinking that and this is wishful thinking, not because someone has researched this. Okay. That you go to a different planet, you can take a geologist there.

they'll be comfortable there because they'll know what a rock of you know there's an interesting.'Cause they see their crap everywhere. Yeah, that's right. So the rocks and the minerals, there might be some more exotic ones. Exactly. But they have a sense of how what elements do when they're heated For a certain amount of time under pressure. And that repeats. depending on the planet. So we can a so there

general rules of geology that apply to all planets. So let's go to biology. Okay. Could the DNA molecule be a natural consequence of complex chemistry operating on planetary surfaces. It could it be as natural on a planet as rocksharks are to to the to the geologist. And that that's what I was about to ask, and both of you can chime in on this. How cheap is life?

So forget if it's inevitable, how cheap is life? I don't know what that means. Well in the sense that it formed relatively quickly on planet Earth. So it didn't take an enormous amount of time. If it took billions of years you say, Whoa, that was some hard stuff. Yeah. We used to how long do do you think it took? I think it's a little bit more than a

Okay. What would you say now? Okay. We used to say that because you'd start the clock at when Earth formed. Right. Right? Four and a half billion years. Yeah, yeah. And then the early early signs of life are like three point eight, three point nine. So you say six hundred million years. ثم نحن نحن نحن نحن نحن نحن نحن نحن

There was periods of heavy bombardment where the surface of the earth could not have sustained complex chemistry. Of course. Because the energy is so high it breaks apart all you let the earth cool for goodness sake. So the cooling y you it let it cool so at about four billion years. It's half a billion years. At four billion years, now you start the clock. And you have life two hundred million years later. Wow.

That's really great. Right. Yeah. Right. In the grand scheme. In in the grand scheme. Yeah. So that's what I'm saying. So life is pretty cheap then. Yeah, it's it's five percent of the total time. Earth has been around. So again, however, I I think that's likely the way to talk about it, but there are so many detailed physical chemical processes that maybe they just so happen to come together in this one planet of the trillion. that are out there. So when we understand it better

That cheapness we may explain it by a coincidence of a whole lot of factors that just happen to align on our planet. I don't think that's how it's gonna turn out, but it's a possibility. It's a possibility. Yeah. Well, except that, you know, there are amino acids on On meteorites. Yeah, we found them already. Right. Yeah. Yeah. An interesting question though is the way that proteins are coated by amino acids is uniform across all life. It's the same code.

Three base pairs on the genetic code give rise to a particular amino acid. That is the code that works for you, me and all life. On another planet, if there is other form of life, the deep question will be, is it the same code? Right. Or is it different? So doesn't need DNA at all. Right. Right. And so if it's different, that would be wonderful. That would suggest that life in a whole variety of different forms can exist throughout the universe.

All right, this is Aaron Bailey who says, Hey Star Talk. I am Aaron from Florida. And and we're sorry. Um, yeah, so Aaron says long time viewer, first time subscriber. Thank you, Aaron. We appreciate that. According to Einstein's equation.

Is time travel still possible if you are traveling to a black hole? And why can't we use gravitational detectors to measure the properties of dark matter? So on the first question, yeah, I mean Einstein's special and general relativity both embrace a certain kind of time travel.

And the black hole provides the mechanism for one kind. If you go hang out near a black hole, time for you elapses more slowly compared to someone who's far away. Famously portrayed in Interstellar. And so if you go to the edge of a black hole and you hang out and then you Then you come back. Everyone that you meet is gonna be much older. Their clock was going much faster than your clock.

And that is some people say, Well that's not time travel. That is time travel. You've traveled into their future, which would have been your future if you stayed there. The black dude. He came back like, oh god damn. Twenty three years. Six you know. You know, I'm on social security. I don't get it. You go down there, you tell me you come right back. You worse than my kids, you're worse than my kids. You worse than my kids. I don't get it, man. Matthew McConaughey.

All right. What was the second half to that question? And so the second half he says Why can't we use gravitational detectors to measure the properties of dark matter? Well, we do. The way we know dark matter exists is by the gravitational influence that it has on its environment. What we're unable to do is identify what the dark matter is made out of.

And so we have these detectors all over the planet trying to capture little particles of dark matter. If that's the right explanation. Right. We haven't been able to find any yet. Okay, you know they're pulsars. Rapidly rotating neutron stars. In a very precise way. Extremely precise. Right. And they're across the galaxies. They're not all that many of them, but there's enough to map out the galaxy. So if you precisely know and measure the pulses of these pulsars, you can track.

A gravitational wave moving across the galaxy. Yeah. And you're kinda using them like buoys in the ocean. Good analogy. Beautiful idea. And you don't even need LIGO for that. Yeah. You just need height sensitive uh uh high precision time. Yeah, for gravitational waves of a certain wavelength. This is a beautiful way of detecting their influence. Super cool, man. Yeah. All right. Let's move on to Alex Frias, who says Hey Doctor Tyson, Lord Nice, Alex here from Mexico. Oh, I should say Alex.

No, Aleksandro. Aleksandro from Medical. Isn't that racist that you assume? I could be racist. I'm black. I don't know if you realize Okay. The world invented racism for me. Okay. Okay, here we go. He said I tell you I tell you. It was I I was given a public talk and I was I thought I'd say something funny. Right. I was talking about the dinosaurs and they went extinct by an asteroid that hit the Yucatan Peninsula Yucatan Peninsula of Mexico.

And I said, um, but that's not what the dinosaurs called it. Okay. I thought it being funny. I thought it'd be funny. Right. I thought it'd be funny. And then someone in the front row said, they called it Mexico. That's funny too. Spanish. Spanish full of dinosaurs. Yeah. Okay. All right. And then you had Tromposaurus, who was just like

Keep em out. Anyway, uh I've always been intrigued and confused by the idea of super sim symmetry. Ooh, nice. If the standard model of particle physics is one of the most successful theories we have. What is telling us that it needs doubling up? What would supersymmetry fix in our understanding of the universe? And what problems might it create? Thank you both and greetings from your neighbors.

Uh in the beautiful upper west side. Oh nice. Oh look at that. Way to go, Alex from right up the street of Manhattan. So let me let me sharpen that even further. Sure. So the standard model is quite an organizational map of our particles and our forces and the like. In its current state, now that we've got the Higgs. Is it missing anything? Is it a closed box right now? And

If we do anything to it, does d does it simply make it more powerful, or do we know we need things to explain other things that we don't yet understand? Good, good. So the the main motivation for supersymmetry is to address exactly the way you frame the question, which is when we study this Higgs particle, this newest Edition that we found on july fourth, twenty twelve, at least that's where the announcement was. When you look at the mathematics, it says that the mass of the Higgs particle

should be much, much bigger than the mass that we find. And when we try to keep the mass at the value measured, we have to stand on our mathematical heads to do so. We have to tune and tune and tune. If supersymmetry were true, the terms that would push the Higgs mass up, they cancel out from those pairings. That's why we need the pairings. That's why we need the doubling. And if you can cancel out the new contributions.

You can rest easy, the Higgs mass will stay at a small value. So how many more particles come along? It doubles it. It really does. For every known particle there is a partner. Electrons have super symmetric electrons. Squirks, neutrinos. Snoutrinos. No. No. Yes. No. Yes. I don't name'em. Snoutrino. No. Yeah. You know why?'Comebody when they found it, they were like, uh neutrino, Snoutrino. And and so the big hope if you would have

spoken to me when I was a graduate student in the nineteen eighties. The big hope and the reason we believe that string theory might be five years away. was we expected super symmetry, which is the super In superstring theory, we thought it would be found, those particles would be found at the large hadron collider. And they were not found. Wow. Well, y that's probably true because the collider has a limited energy reach. Nothing in our theories tells us.

How massive the partner particles would be. If they're sufficiently massive, they'll be beyond the reach of the large hadron collider. So there's a natural explanation for why we didn't find the particles, but we were certain that we would. He wants another collider. Yeah, there you go. You don't need one. Look at that. Well, that is fascinating though. Okay. Um and and does the Higgs have the the do we have a name for the other particle?

Higzeno. Higzeno. Yeah. I prefer squigs. And how about a f the photon? What's the symmetry? Photino. Really? Really. Okay. And the W and Z bosons, those are harder Xenos or Winos. We know's getting a little funny. Well, you see, the supersymmetry that we're talking about doesn't have gravity in it when you're just talking about the standard model. Oh standard model doesn't have gravity. Yeah. But if you include gravity, then there is a version. It's called super gravity.

And it comes out of string theory as well, and it's the gravitino. Right. It's from the graviton. Yeah. Right. Okay. Okay. All right. All right. Well, way to go there, Alex. We're still looking for him. Yeah. Is this just a matter of A lack of detectors. Could you build enough detectors where we could get all this

Capture all this stuff? Not so much detectors, it's a matter of the energy. So how big the detector how big the collider is. And that's you know, colliders are expensive and the bigger they are, the more money they cost. And we had a big one going in our you know, our in our side of the pond. Mm-hmm. The the superconducting supercollider in Texas, funded in the nineteen eighties. uh under Reagan and dug the hole, got all ready, Waxahatchie, Texas.

It would it would be three times as powerful, I think. Yeah. About fifty T E V and we have fourteen T E V. Yeah, yeah. So three times the power of the of the one that was built in Switzerland. And then early nineties they zeroed the budget. And they said all those cost overruns and that's quite a thing. But but

Oh some kind of defense thing. We no longer were fighting for AI. The fall of them. Yes. Yes. Peace breaks out and all of a sudden it's like we don't need physicists. What do we need physicists for? And their little toys. You never heard of cost overruns in any other particle accelerator for the whole 20th century. Right. Interesting. This is Blake who says, hey, it's Blake. Greetings from warm sunny.

Columbia, South Carolina. Wait a way to rub it in there, Blake. He says there are quite a few theoretical particles that have been discussed on this show, the Graviton, the tachyon, strings, etc., but we don't seem close to actually finding any of them. Are there any exceptions? Experiments proposed that might help us capture and learn about these elusive particles if they exist, and slightly more an engineering question if we did find them.

How might we use them for the benefit of humanity? Uh do they have a use if we find them? I mean Well, if dark matter is actually found and it is a particle, look, it'll deepen our confidence or understanding, can I imagine applying dark matter particles to build something?

the whole point is they're incredibly elusive. They only interact gravitationally. How do we even capture them if they don't interact with anything? Well they do interact with themselves. They interact with themselves. Yes, but anything that has energy interacts gravitationally. And and these dark matter particles through indirect quantum processes do interact with ordinary matter. And that's how these detectors are set up.

Uh is that the energy. Yeah. But it's the same basic idea. Okay. And so yes, you can detect these things, but that's different from gathering them together and engineering with them. So I don't I don't see any direct benefit that comes out. But again it's the same argument we made before. The deeper your understanding, that's step one. And then someone figures out where that goes. Okay, gotcha. All right. This is Luke Sr. who says

Best regards from Joliet. He says, Dr. Luca Laporta, PhD translation scholar and uh Sinologist. He says, Could it be the entanglement phenomena? Is simply a matter of absence of the time dimension at the scale of the particles. and that we see two particles interacting instantaneously at a distance in some his word, magical way, In their own three dimensions only universe, they're just unaware.

that a change of state has occurred, that for them there's no before entanglement slash after entanglement. Thank you very much. It's a very well thought out question. What it w does it make sense? I i it does and I think we can interpret it more or less along this wormhole idea that we were describing before. The wormhole notion, again, this is Still very much at the forefront. We're still working out the details. But if it is the case That two distant particles

are connected by a wormhole, if they're entangled quantum mechanically, then it would be as if they're right next to each other. And so that's a variation on the same thing. I don't think you can say they live in a world without Time because the conundrum is to us beings that do have time, you do something here and it instantaneously, according to us.

affect something over there. And that would still be a puzzle no matter what. And one explanation would be well, they're actually closer together than you think by looking at them because they have this secret shortcut connection which could be the Worm World. So I think for so many years people were imagining wormholes as some kind of Uh ride or in a water park. Exactly. You know, even in the movie Contact. Right. Jodie Foster is going through but no, you just step through it.

Effectively stepping from one place to another. They had a portal. Where it looked like a doorway threshold. City on the edge of forever. Yeah. And that's a wormhole. You step through it and you're already there. There's no ride, there's no nut you just Step through it and you're already there. And that's another one where they were gonna save someone's life. And they decided not to. Yes. In fact, I was I was talking with Bill and

Uh he said that was his favorite episode. Oh really? Yeah. Yeah, it's my favorite watching as a viewer. Yeah, just because it was it dealt with time travel in a very emotional way emotional and unorthodox way. Yeah. And causality is is actually addressed.

All right, Zachary E says, hello, Dr. Tyson, Lord Nice, Dr. Green. Is it possible that through the many worlds interpretation, quantum immortality can become macroscopic? If every single possible state of every single particle in existence is equally real, I feel like the superposition of a single particle in quantum immortality theory can be expanded to incorporate the superposition of every single particle. in existence.

Yeah. And look, you know, another way of saying it is we said before that the many worlds allows a world in which anything compatible with physics is realized. Us living to a hundred, two hundred, five hundred, a thousand. I don't know that there's a law of physics that prevents that can happen. Now there is a law of Jesus on bored that will allow that. The boredom the boredom who can you imagine living a thousand years? Ugh. Who I'm oh kill me. Just thinking about it, I wanna die.

So wait, here's something that we did not raise, which was if there's another identical me, yeah, is it me? That's the deep question. That is the question. And I think the answer to that is yes. No, but I think the answer is no. Why? Because we've already kinda done that experiment. They're called twins. No, but I'm saying that person has literally your memories, literally your self of sense of self until something measured.

That causes you to be different. From that. Yeah. Yeah. So it's truly you. That's wild. I mean, if if if I spoke to that version of you, you would adamantly c claim yes, I'm the same guy. That's me. It's me. It's me, damn it. That's I don't know what to say. I've never heard you say that before. So that means w we are living forever. They're reincarnation. Yeah. Are all over this. That's right. Right. Mm.

Wow. Or at least extraordinarily long. Uh you know, maybe there is some physical law about maybe the proton decays in ten to the thirty eight years of you know that kind of thirty eight. Yeah. Or ten to call ten to the whatever. More than ten to the thirty two. Wow.

All right. This is Marcus Ruzon. And Marcus Ruzan says, Hello, Neil and Brian. Love the show. I've been wondering something about time and light. If nothing can fat travel faster than light, and the speed of light is a universal constant, Could it be that time itself? is actually an emergent property of light. Is it possible that what we perceive as time is actually just a consequence of us travelling through space time at a finite speed below the speed of light?

Is that not confirmed by the fact that from the point of view of a photon there is no time thanks and keep looking up from Singapore. Yeah. And it in some poetic sense I agree with what the questioner asks. They're saying that if a photon had consciousness. Right. From its perspective, it would not know it would not know that time is elapsing. Now I think it's really important to recognize that

You're extrapolating Einstein's result to a particle for whom the equations don't literally apply in the way that we're using them. Correct. So if you apply Einstein's ideas to any massive body, you find that they can't travel at the speed of light. And therefore they will always have this conception of time. But if you want to push it to the absolute limit, which I call poetry, not quite mathematics.

Then yes. Right. Because the key is the photon has no mass. Yes. That's the key. Yes. That's it. Yep. So once you have mass, you can't be a photon and you can't you'll never experience what that photon experiences. Precisely. Okay. Well there you go, Marcus. But thanks for the you know. I had nothing to add to that. All right. This is Patrick Diet.

And Patrick says hello, Doctor Tyson, Doctor Green, Lord Nice, Pat Dietz from Ravenna, Michigan. Could the reason we cannot see dark matter also account for the expansion of the universe due to dark matter moves faster than light? Let me read that again. Could the reason we cannot see dark matter also account for the expansion of the universe due to dark matter moving faster than light? Okay. That's a tough one to parse. It's been really rough, but yeah. I see what he's saying.

How can you see the thing that's faster than the thing that allows you to see the thing? Right. I get this sort of uh collection of words, but the problem is Okay, by the way people this is why I love scientists. Without without ever saying those words. The important point is that for a particle to be a particle of dark matter it has to have mass. Right. Once it has mass it can't travel faster than the speed of light. So the ideas don't

meld together in a consistent way. There you go. All right. I like the question, just for the fun of it. All right. Thank you, Patrick. Uh this is Mr. Zoot.

And mister Zoot says, Dear Star Talkers, Jeffrey here, pronounced Jeffrey Chuck. Screw you, Mr. Zoot. He says, I understand electron orbitals are really probability clouds, but still exist in discrete energy levels around the nucleus. What then happens during ionization? Do they stay as a probability cloud, just untethered from their anchor, so to speak? Do they still have discrete energy levels? Hey, what gives? And thanks.

So if that is a great question, somebody's thinking. And so it certainly does stay as a probability cloud or probability wave if an electron is ionized, say, from hydrogen. But if that electron is living in a universe that is not a box that's infinitely big, then we don't believe its energy levels will be quantized. Then the energy levels are quantized, but they are dependent upon the size of the box.

You're expanding the what's it called? The harmonics. The harmonics of the wave. And the harmonics have to die. They have to fit inside the box. But if there's no box, then they could have any wavelength at all. The energy of a free electron is not quantized. Correct. I did not know that. That's I've never heard of that before either. That makes that's w that's wild. Wow. That's absolutely wild.

Very cool, man. Wow, great, great question. Uh Jeff. Just a highlight, because he said something important here. So what's we'll call it a box. But let's let's let's look at a tube. Let's look at a like a a a an organ tube. Okay. Okay. So What kind of wave can you set up inside that tube? And it'll can only hold a wave.

where the complete wave is there. Right. You can't hold like a half a wave. Right, right. So it sets what the wavelength is. So the the the the the frequency of the sound, that's the wavelength. um you get that from the wavelength in each tube. So different tubes have different frequencies that resonate inside of those tubes. Right. And so when I think of atoms, I think of you got the nucleus with the protons sets up a box.

And so you then you do the math and you get a set of wavelengths, I'll call'em that, that fit inside this box and it's unique for every atom. And that's what gives you the spectra of each atom. That's where each atom has a unique spectrum. Right. Yeah. It's really cool. That is excellent. Wow, I learned stuff on this show. It's so great. So did I. I I I just never thought about free electrons and their energies. Yeah. Okay.

Um this is Brian Nadu who says, Hey Dr. Tyson, Dr. Green, Lord Nice. Brian from upstate New York here. Would the discovery and verification of the graviton assist at all in reconciling general relativity and quantum I love that isn't it just assumed that there's a graviton? And that assumption needs to be verified, hopefully. Aaron Powell And what's the energy of a graviton relative to the waves that we just detected? Well, the energy that the mass of a graviton we believe Uh is zero.

Because gravity also travels at the speed of light. Oh so it's much like a photon in that particular way. And yes, if we could ever really detect a graviton to it Experiments with gravitons, scatter gravitons off of each other, then yes, we would learn an enormous amount about general relativity and quantum mechanics. That's right. In fact, the very existence of a graviton would be the first evidence that gravity is quantized. And so we're assuming that

There is a graviton, but verifying it would be a huge stuff. The idea of the graviton? I don't historically know. So but Einstein was the gravitational wave. Yeah. Well you have a wave. He was a reluctant gravitational wave person. He was really uncertain in nineteen sixteen and nineteen eighteen about whether they were real. Okay. Amazing. Yeah. Yeah. So so I'm just saying w the quantum assumption is that where you have a wave you also have a particle. Yeah.

And like the photon is a wave and a particle. Okay. Mm-hmm. Wow. Okay. That's super cool, man. That's a good question though. Who first introduced the very idea of a graviton? I don't know the answer. It feels kinda natural if you if you're if you're gonna look that one up quantum quantum quantify.

Alright, this is Tash. Pshaw and Tosh says Dear Doctor Tyson, doctor Green, Lord Nice, I'm Tosh from Orange, Australia. I'm a longtime listener, so my boyfriend bought me a subscription to Patreon for Christmas. Oh nice. Very nice. What a nice boyfriend. Very nice gift, yeah. Yeah. That's a smart man.

I have read that other dimensions could potentially be detected through gravitational and other anomalies. I was wondering how we would be able to distinguish these from any effects of dark matter. So Would there be dimensional d differentiations? Yeah. In fact, uh a proposal that was made a while ago is that at a collider like the heart large hadron collider, when you slam protons together

You can calculate and measure how much energy you have before the collision. You can measure how much energy you have after the collision. And if we have less energy after the collision, that energy must have gone. somewhere. That is so cool. And the possibility is the energy went into the other dimensions. And so this was a missing energy signature of extra dimensions that we were again hoping we would Why would you presume that and not

As what occurred in the neutr first neutrino experiment. So it could be some other particle, mysterious particle carrying away. An imbalance. Yeah, there was an imbalance. There was like you start with this much energy and they have less. Right. And you accounted for all the particles. Right. So maybe there's another particle. But what's up with that? And they say if there is a particle It has to ha be neutral and it has to be l very low mass. And the guy who proposed it was Italian.

So little neutral one, neutrino. Oh. Like bambino, little baby. Bambino. Neutrino. What you got, Jack? Let's go to cosmic ma.

Says hello everyone. Love the show and every star you've had on it. You guys are great. I love the way you teach. Please keep the education up. Doctor Tyson, Dr. Green could theoretically a frequency be matched at two points in space by a microparticle uninhibited by resistance. only to be met by its astrophysical counterpart. Neil, I think you should take this one.

and then it's a counterpart that impedes, I guess, the entanglement. It's kinda like Okay, read the first sentence again. All right, he goes. Uh could theoretically a frequency All right, so that's the I guess his version of the string string. in space by a microparticle. So that's the entanglement. Maybe uninhibited by a resistance. only to be met by its astrophysical counterpart.

The only counterpart particles are antimatter. That's it. Yeah, there's no other That's what I'm saying. And there's not much antimatter in the universe. Right. In fact, well, other than the centers of stars, we probably make all the antimatter there is in the universe on Earth.

Would you say? I haven't done the calculation, but I can imagine that. I mean just think about that. Most antimatter in the universe will get annihilated finding matter. Immediately in the centers of the sun. So uh The cool part was in one of the Dan Brown stories, the Catholic Church had a vial of antimatter that they That's so funny. Dominus the spirit oh, he's gone. Physics jokes

All right. So yeah, I don't I'm not qu quite clear. If it met its astronaut the counterpart, it would annihilate no matter what else is.

Hey, Dr. Tyson, Dr. Green. Sup Lord Nice Kenny from uh Dothan, Alabama. Is the reason why we can't reach the absolute zero degrees in temperature because of the CMB is it due to the act of time using energy to move forward, creating heat? And if we were to reach absolute zero degrees, would space time move forward in that region? Yeah. So yeah So my understanding of absolute zero is

That you know, all particle motion stops except it doesn't because you have quantum fluctuations, even at absolute That's the key point right there. Okay. That's the real barrier. Okay. So but why isn't the cosmic microwave background a barrier? Well, if you didn't shield yourself from two point seven degree photons, they would influence. But presumably if you're able to shield your environment. Yeah, but the shielding would have to be temporary because the the heat transfers. Yeah, sure.

But an experiment takes place over a period of time. So as long as your time scales are set right. So I think it's really the uncertainty principle is a true barrier against truly having particles at a definite location, not moving. That would mean position and speed were both nailed down at the same time. Which is not happening. You're not gonna do that. Not happening. Wow. Yeah.

So the wave function would cease to exist if you were ever to get to the place where you could get the particle to stay. Exactly frozen, like still and definable in one point. Okay, so what is the temperature of that state of matter? Well, it depends on the details. I mean you can calculate the quantum fluctuations of a field and if you tell me how it interacts and its mass. You can calculate its quantum fluctuations, and indeed that's how you make predictions about the Casimir effect.

Oh. Evacuated completely. And yet those plates can pull together because the fluctuations of the field inside are a little bit less than the fluctuations outside and that imbalance. You can actually calculate it and you can determine how the plates come together. That is so freaky, man. It's all freaky. That is so freaky. I love it. It's all freaky. Oh my goodness. And then and then they attract. Yeah. Yeah. Yeah. Right. You freaky dude.

So we should do this every week. What do you think? No, Brian, you have a life. Thank you, Brian. My pleasure. This is great. You're working on a quantum physics book. Yep. Yep. This is the decade, the centennial decade of the discovery of quantum physics. So we can't have too much quantum physics.

out there. And this is for the general public? Yeah, so we're finishing it up now in twenty twenty seven. It should be out. Get it out in this decade. Yeah, that's the key thing. Okay. All right. And this year we're recording this in twenty twenty six. This is the centennial of Edwin Hubble discovering that the Milky Way is not the only galaxy in the universe. Wow. He uh he discovers that Andromeda is not just a fuzzy spiral.

sitting within our stars. Right. It's a whole other uh island universe out there. I love that. That was a hundred years ago. So uh this has been a special edition because it's an extended conversation with my friend and colleague, Brian Green, right up the street. At Columbia University. And delight thanks for spending the afternoon in my office. My pleasure. It was great fun. All right. And Chuck.

Always a good baby. Yes. And catching you on YouTube were just smart enough. That's right, on the Star Talk YouTube channel. Were you just smart enough for this conversation? Today I was the dumbass. And happy to be so. All right. Till next time, Neil DeGrafton. Världens kanske mest ikoniska handbörjare behöver ingen introduktion. Du vet att den består av 100% nötkö och är oemotståndligt god Big Mac och Company. Det vet vad den finns. Bara på McDonald's för bara 79 kronor.

Det kan verka som att det inte går. utan fossila bränsen. Men med fossil fri elektricitet.