Exploring Hidden Dimensions with Brian Greene

20:23Neil deGrasse Tyson:You have matured in the past. I have. Because I don't, 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 if you have polygons, which are flat shapes that have the same sides on them, so a triangle would be a regular polygon, a triangle, a square, a hexagon, that sort of thing. So if you ask, can you make solid objects with these as its sides? Right. There's only five. Five shapes that do that.

21:05Neil deGrasse Tyson:Five shapes. That do exactly that. Where each side is the same polygon. Okay. Only five. Right. One's a pyramid, definitely. One's a soccer ball. No, a soccer ball has two different kinds of shapes on it. Oh, really? Yes, it does. Oh, so they're not all the same. No, they're not all checked next time. All right. But it is a way to tile a sphere. Tile them so that you can do it. So one is a pyramid. Another one is a cube. Cube, of course. Right. And then there's like three others given to me. Yeah, dodecahedron and I don't even remember the rest of the name. Icosahedron. Yeah, so. And there's another one.

21:36Neil deGrasse Tyson:Okay, so now, Kepler, a mathematician, said there must be some divine reason for this. For these shapes. And we have six planets. There was Mercury, Venus, Earth, Mars, Jupiter, and Saturn. So he said, wait a minute. If the universe is special, and math is special, obviously, they have to be connected. They must be connected. So he embedded these platonic shapes in each other, 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 connection. So he spent 10 years doing this.

22:17And then it was over, he was like, I've wasted my life! Oh God, what have I done?

22:22Neil deGrasse Tyson:But the math is what took him there. The beauty of the math. And so that was my lesson, that I ain't going there. But it goes the other way too, right? Because you go back to, say, George Lemaitre. So he's a priest, a Belgian priest. 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.

23:02Einstein's math was relevant in the way that George LeMaitre was suggesting the universe is expanding. So you have to go...

23:09Neil deGrasse Tyson:Einstein didn't even know his math was relevant. So Le Matric, he used calculations of Einstein's equations to force upon him a feature of the universe that not even Einstein was imagining. Exactly right. So that's math being badass. The math discovered that. The math discovered it. Yeah. So it's all just to say that it has to be case by case. You got me. No. Wow. 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. It's infinite in any reckoning, but exactly which kind of infinity?

23:52We 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 track. Yes, in fact, he published General Relativity a little bit before Einstein did. It's a little known fact. What's his name again? His name is David Hilbert. Damn. I don't know Hilbert because it's Hilbert Space.

24:20Neil deGrasse Tyson:Hilbert Space. You have to tell me about that in a minute. But in this particular story, Einstein had visited Hilbert in June of 1915, showed him everything that he'd worked out for 10 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. I'm not trying to take it from you. That's very cool. But he did publish a little bit before him. Even though he would not have published had Einstein not visited him. Yeah, he wouldn't have known anything about this. But Albert is a brilliant guy. But the point for quantum mechanics is that there is this thing that you made reference to, Hilbert's space, which is the mathematical structure within which all these worlds live.

24:57And we understand the math of that pretty well. I did not know that.

25:00Neil deGrasse Tyson:So why does it need a mathematical structure in which they live? Well, if you're going to describe things with rigor mathematically, you've got to define things. You've got to 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? You know, everything. Who's the dude with the incompleteness theorem? Yeah, Gerdel. Gerdel. Yeah. So, yeah, so Gödel 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.

25:44Neil deGrasse Tyson:So it just has to be asserted. It has to be asserted or you have to somehow intuit it or feel it or, you know. In the general relativity. That sounds a little suspect. But the deep question is, are there interesting physical features of the world that would be undecidable in this Gerdelian sense? That's what I'm asking you. So is there a feature of general relativity where you part the curtains enough and then there's just some assumption you had to make? Yeah. And everything issues forth from that, that you cannot deduce from anything that follows. Yeah, I mean, there certainly are axioms within these theories for sure.

26:20but are there then deductions that are true but can't be proven within this structure itself? I don't know because when you look at Gödel's proof, the kinds of things that are undecidable are very contrived. Things like the set of all sets that are not subsets of themselves. You're like, well, does that ever come up in the real world? Or the barber of Seville, nobody shaves themselves, but then who shaves the barber? so they're all very self-referential and it's not obvious that they have direct relevance to things that we could

26:56Neil deGrasse Tyson:measure but it's still an important discovery hugely important and this thing about the closest I got to that barber question was I used to read brain teaser books when I was a kid and so one of them was you come to a town and only two barbers and one of them was just completely messy and the guy's unkept and his hair all but the town looks amazing and there's another barber where he's clean He's shaven. He's everything's neat. So which barber do you go to? I'm going to the messy one because he clearly does the other barber. Exactly. Exactly. Somebody cuts the guy. That's the guy. That's the closest I've gotten to the barber.

27:34Neil deGrasse Tyson:So with the many worlds, now connect that up to a multiverse. Yes. It's 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? It feels less real to me than other multiverses I've read about. 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.

28:11In some universe. Yeah. Now let me ask you this with respect to that. How do we act to this? Give me a second to like just tear up. See, I watch a lot of Rick and Morty, so this doesn't bother me. It doesn't bother me at all. I'm just like, oh, okay. Of course it works that way.

28:28Neil deGrasse Tyson:Duh. But this other me, that's me identically, except we observed a 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. Because I've seen in several films, but let me pick one specifically, H.G. Wells' The Time Machine. I'm referencing, I didn't read the novel, but I saw the movie, when is it, from the 60s. And the guy, the main protagonist, befriends a woman who shortly after they have this encounter, she's like hit by a truck. And he says, well, I have a time machine.

29:11Neil deGrasse Tyson:I can go back and fix this. So he goes back and says, oh, don't exit the park 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. One anvil. Right. And even better. Right. 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. Can't change the outcome. Okay. But when I saw that, I said, the molecules of air that are around her are in a different place because she's displacing these molecules relative to these. That's a different universe.

29:48Neil deGrasse Tyson:I'm not going to 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. If the person could really go back in time, change things, I think you would get a different universe. 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's completely different. If you take on board this idea, you are committing to different worlds where things are radically different.

30:28And one, she would live, and the other, she would die. 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 things compatible with the laws of physics are realized. Wow. That's pretty wild, man. Okay. But all right. I love that though. 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 infinite number of worlds

31:05Neil deGrasse Tyson:let me get there so watch we went from the many worlds hypothesis where it is exactly me but I 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 a many-worlds Neil. You're Neil who believes in tarot cards. So that's not a many-worlds Neil. That's just another statistically configured Neil out of the random molecules in that universe. 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.

32:03Okay. 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.

32:13Neil deGrasse Tyson:Right. But in that world, that's a different me looking at the cat because the dead cat, live cat version of me, they each have a goatee. 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 and one you without a goatee and 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 possibly yeah now one of them results in you having a goatee because that came along for the ride in that particular world so here's what i want to 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.

33:07But the universe could go on infinitely far. Okay, then that answers my question. We don't know. Because my point is, 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.

33:28Neil deGrasse Tyson:But even with an infinite number of universes with the same number of particles, you just configure them and keep reconfiguring them. My point is this. Can you reconfigure a finite number of particles to get to infinity? You can't because it's not reusing the same electron or the same proton in one world and another. It's a realization of that particle in a different configuration. Right. And that's not like a conservation of particle number. I got you. So I used to be into big numbers. I still am, but I haven't stayed with it. And one of my favorite big numbers was skews number. Do you know skews?

34:04Neil deGrasse Tyson:I don't know skew's number. It's 10 to the 10 to the 10 to the 34th power. Okay. And if you play that out, you get the total number of configurations of all the particles in the observable universe. 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. Because you're not counting objects at this point. You're counting events. You're counting things. Combinations. Combinations. 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.

34:42I would get a 10 to the 10 to the 120. Okay. Is that much different from 10 to the 10? Yeah. So I think it has to do with whether you're only looking at material particles. Yeah. Yes. Yes, it is. Versus the energy that. Oh, no. Of course. Yeah.

34:56Neil deGrasse Tyson:The energy is all in there, too. Yeah. Yeah. This is just counting up the physical particles. Sure. That makes sense. Okay. Okay. Cool. So do we actually know the amount 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 distant galaxies are accelerating away from us. 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 an issue.

35:34This issue of infinite number of worlds.

35:36Neil deGrasse Tyson:Wait, just before you get there, I just want to 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 infinity and you get a real number. And you get many worlds. You get many worlds. In which that small probability thing could happen. Exactly. So the infinity that we're about to go helps bring out of the depths 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.

36:15But 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 some world. So what does it mean to say something is unlikely if you're sure it's going to happen in some world? It's like having a drink. It's five o 'clock somewhere.

36:46Neil deGrasse Tyson:So we encounter this in astrophysics where we talk about supernovae as being an extremely rare event. Okay. Not all stars will go supernova, even high mass stars, some go black hole. It's rare. However, the galaxy has 100 billion stars in it. There's 100 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 catalog. It's a rare event that happens often. Exactly. So that was initially kind of hard to explain to the public how you get that. 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.

37:41Right. 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.

37:56Neil deGrasse Tyson:interesting so let me ask i think we chatted about this over lunch a few moons back thanks for inviting me oh it's in your inbox

38:10Neil deGrasse Tyson:and forgive me i might have had this conversation with brian cox so i'm sure yeah yeah forgive me because you're my favorite physicists out there so but so do you feel bad that i have another physicist who i a little bit 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 there are at least five you can keep on going all right yeah you buried the lead guys now you got to explain that you can't just say that you weren't at the lunch move on should i that there are levels of infinity yeah yeah yeah but do you want it do you know how counterintuitive that is i know you weren't at lunch so should do i have to drag you behind us i know man listen i'll take a doggy bag okay because that's crazy what you just said 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 maybe needed 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 because i don't know that science understands you and by you i mean life well enough to say you know what you said he said i could be so simple it's right It's trivial to copy.

39:41Science is under no obligation to understand you. 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 in the quantum mechanical infinity to reproduce you and to reproduce every variation on you where some of your particles.

40:04Neil deGrasse Tyson:Every variation conceivable. Yes. Yes. Every variation allowed by the quantum laws, which simply means. Listen to me that 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. Non-dental plan. This is the Neil with no dental plan. If that's within the bounds of quantum mechanics. The laws of physics don't prevent it. The laws of physics don't prevent it. Then we got enough material to make sure that that happens. I don't need the higher levels of infinity to get there. No, absolutely. Okay, so now let's catch up, Chuck, because everyone else out there knows about multiple infinities.

40:43Neil deGrasse Tyson:So, these are levels of infinity. I think there's a Hebrew letter associated. Aleph. Aleph. Aleph zero is 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. That's the simplest infinity. 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?

41:15Can I put them into a correspondence with the counting numbers and just list them? However, but am I not? But I'm still going towards infinity. In fact, I was going to say, aren't I dividing then when I go in between numbers? Yes. I'm kind of dividing now. You are, and you could say, well, let me put a dot in the midpoint, call that one, and then a dot and a midpoint between it and zero and call that two. You won't cover all the numbers. And there was a wonderful— I'll never reach one because 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.

41:54We'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, and 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. That would be Alice one. Alice, give me my bag. I'm going to need my weed.

42:20Neil deGrasse Tyson:Okay, so you just skipped by it and I want to 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 get that? Well, you know, you could take any given number and say multiply it by two and add one to it. And in that way, you're certain to get an odd number. You get an odd number, and now you've lined up the numbers one, two, three upward and the list that it corresponds to are all odd numbers.

43:02They all just go up. Yeah. Damn, that's wild. Wow, math is kind of cool. Who knew?

43:10Neil deGrasse Tyson:Okay, and just to taste it, if I remember correctly, Aleph 2, does it go into another dimension? The number of lines in three-dimensional space is a bigger infinity than the counting numbers on a number line. 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, 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 astoundingly strange idea, which is why mathematicians who thought about this in the early days.

43:52You're all in asylums right now.

43:56I'll never get to one. I'll never get to one.

43:59Neil deGrasse Tyson:I'll never get to one. I'll never get to one. That is so rude. That was so rude. So, and if you go to higher dimensions, in principle, does that take you to greater infinities? No, I mean, if you start to look at the number of points in the plane. Points on a line versus points in a plane. So you have to be fairly sophisticated in how you build up these infinities. Okay. But for our purpose, there is this thing that we've made reference to. It's a bit abstract, this thing called the Hilbert space. And we understand it reasonably well. It's an infinite dimensional space that David Hilbert developed.

44:40But we understand it well enough to say it does have enough room to embrace all the quantum mechanical space.

44:46Neil deGrasse Tyson:It has infinite dimensions. You think it has enough room? Yeah. 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 thought much about whether or not something can exist and whether or not it does? The likelihood of such things? Yeah, and it's a mind-blowing thing. Tell me. When you think about the sequence of steps 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.

45:28Let's go all the way back to the Big Bang. And if you look at the sequence of steps from the Big Bang.

45:32Neil deGrasse Tyson:I have ancestors that go back to the Big Bang. You do, actually. We all do, as a matter of fact. We all do, right? That's how we get here. You know, 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. And 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?

46:07Well, I think it gives you a certain... You want me to feel special? Well, you know, if you want me to be a little bit sappy, you know, I think it inspires a gratitude. The unlikeness of us being here against being at all. And therefore, it's 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. And the many worlds. What you just said can negate that, meaning that also there are an infinite number of worlds where there's just no Neil.

46:52And then there's an infinite number of worlds where there is no cat. And then there's an infinite number. 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 laws because we are allowed by those very laws of physics okay right but brian

47:33Neil deGrasse Tyson:I have a more anchored version of what you just said that I credit to Richard Dawkins. Yeah. If you look at the total possible genetic combinations that will make a human being, a viable human being. Okay. It's a stupefyingly large number. Absolutely. Like four to the three billion or something, right? Yeah. It's crazy. Or 10 to the 30th power. It's high. Right. Yeah. What matters is not even how big it is. Yeah. But it's vastly larger than the total number of people who have ever been born. Right, yeah. Which, plus or minus, it's about 100 billion. Yeah. Okay? So, Dawkins' point is, we should cherish life because most people who could ever exist will never even be born.

48:19Neil deGrasse Tyson: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... 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 get a chance to live. Then they did live if their genetic sequence was compatible with the law of physics. All right. So don't feel bad for all those little swimmers that didn't quite make it to the egg.

48:55Neil deGrasse Tyson:The sperm you're talking about? Yes, exactly. So, Brian, I get this question often. 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 are you going to cop out and say, oh, they're in the infinite dimensional Hilbert space? Well, it's easier to answer that question for other flavors of multiverse, like the inflationary multiverse that you made reference to before. That's the simplest. That's the simplest one to picture. So those are the places in our own. We're in a bubble. and there's another bubble over there in the same sort of space-time construct.

49:32Yeah, because according to inflation at 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. Some 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 bath.

50:01Neil deGrasse Tyson:Okay, so that's in one construct. Yeah. Okay, but now there are other variants of multiverses where it's sort of separate and detached. Yeah, 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 going to 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?

50:40Not really.

50:41Neil deGrasse Tyson:Okay, so that's a mathematical architecture. Can I divine an experiment that would show that they exist? 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 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.

51:18Neil deGrasse Tyson:Tell me that other universes, gravity can leak out of them. Yes. So that's another variation on the multiverse that comes from string theory, which we can talk about. Oh, we'll get there. Yeah. Okay. But just to presage what 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.

52:00That's where they occupied. Okay. I feel so silly, but they'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. And until you separate them, that's when you can see the different things.

52:48That'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 where they see. I see it as the one card, and they were explaining that they see it as the deck. But anyway, I had shared that with Jan 11, 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 string theory.

53:21So this is something— Brain isn't short for membrane. Membrane. Yeah, yeah, yeah. Sorry, yeah, yeah. I should have said that. Thank you. 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 has mentioned, they can influence each other. Gravity from one can influence things in the other.

53:39Neil deGrasse Tyson: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 whole course on field theory. You can come to my class. You teach? Yeah, I've taught field theory a number of times. I'll let you know next time. Excellent. I sit in the back. Exactly. Boy, that's not intimidating. You snooze fast, Tyson. I'm going to fail. I swear to God, I'm going to fail. No, but I'm not in a position to calculate or even really know why gravity can escape, but not the electromagnetic forces.

54:19Well, I could give you a quick mnemonic sort of to think about that. Really? Okay. 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.

54:50Neil deGrasse Tyson: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 another slice of bread? People have made proposals like that. If you're dark matter is meant to explain the gravity that we know is there, it's dark gravity. 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 into betting, what an outcome would be, an exotic particle is sort of the betting man's solution to.

55:34Neil deGrasse Tyson:Yeah. But that's put forth by particle physicists. You know, if you're a hammer, you're a little bit of bias. A little bit of bias, right? So I'm liking me the gravity spillage. No, I like the idea. 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 string theory. Yeah. Okay? I'm a little older than you, but we came of age with enough overlap. So I can speak of the 1980s as a time where string 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.

56:19Neil deGrasse Tyson:Yes. And Steve Weinberg. Steve Weinberg, for sure. A graduate of my high school. That's true. That's true. Not your high school. Yeah, I agree. Okay. So Steve Weinberg, a Nobel laureate in physics, cosmologist, you know, all the way 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 10 years later well when are you gonna do it oh in five years 20 years later oh in five years the problem is hard it's a hard problem but we're on the and And so I've never heard convergence in any conversation about strength theory landing where it had intended.

57:08A.

57:08Neil deGrasse Tyson: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 let me say that more charitably. Are we awaiting the birth of some 21st 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. It was a sign of enthusiasm. Yeah, 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.

57:51But 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 collider and determine whether these ideas are correct. And it could well be that we just don't have the brainpower 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. If I said five to ten in the next five years, did you hear that?

58:26Yeah, you did. I did hear that. This one I'm willing to stick with, though, because, you know, I'll give you an example. I mentioned this paper that I wrote with Jana Levin that you may reference to.

58:39Neil deGrasse Tyson:Is this the loaf of bread paper? No, 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? Chat GPT. Chat GPT. If I treated it as sort of a good graduate student. 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 to get. 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.

59:17And that's now. This is a hologram right now. It's an A.I. I'm not even here. So what is it going to be like in five years? It's both exciting and scary at the same time.

59:29Neil deGrasse Tyson:I have a colleague who has a similar story regarding his research where he was prompting Chad to think about a problem. Yeah. And it solved a problem that he had not been able to solve. And actually solved it. Yeah, actually solved it. Wow. In the sort of, you prompt a really good graduate student in just the way you're describing. 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.

1:00:05The fundamental particles. 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.

1:00:20Neil deGrasse Tyson:Which is for people who like unity, 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 big. Does it do that for free? It does that for free. It just comes out. I'm telling you, you look at the math. That's a nice fact. You look at the math, right? You stare at the equations and out pops Einstein's equations from general relativity. To whom does it pop?

1:00:53Neil deGrasse Tyson:Who do you have to be for it to pop out? So I had not fully embraced that reality of string theory. So I'm delighted to hear that. So that was part of the enthusiasm that people would have then had. That was really the heart of it all. So then what is the major obstacle? 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. It's tough terrain to cover. And so we've been developing mathematical tools to do that for now 30 years. We've made progress on black holes. The 80s was 40 years ago.

1:01:34I guess you're right. Oh, my God. Strength there hasn't answered that question yet. 40 years ago. 40 years ago.

1:01:40Neil deGrasse Tyson:The 40s before that was the 1940s. Yeah. I'm with you on that. All right. You know, so we've been for 40 years trying to, you know, and so we've understood things about space and time and gravity and black holes, which I didn't think we'd ever understand in my lifetime. Yeah. 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 going to happen at the Large Hadron Collider and let's check it. And so it's an interesting thing that we've made headway in the very things I thought would be too hard. And we've not made headway in the things that I thought we would be able to reach by now.

1:02:22Neil deGrasse Tyson: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. Let me do it anyway. Let me do it anyway. All right. So string theory has not been without some criticism as something that has 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?

1:03:00Neil deGrasse Tyson:I sound 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've got to 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 the choice for where they think the greatest promise is. Yeah, who are you to say that they're not going to? Yeah, so it's not as if somebody was like putting a bag over their head or, you know, putting a gun to it.

1:03:39They were looking at the ideas that were out there, found the string theoretic ideas so compelling that they were willing to take a chance. And that chance may not pay off in our lifetime.

1:03:51Neil deGrasse Tyson:And tell me about the 10 or 11 dimensions. Yeah. Because that sounded very cop-out-y. Well, so when you— It's like, I can't explain this, so let me throw in a dimension. Ah, good, good, good. Let me add another dimension. Let me add another dimension. Why do you need the dimensions? 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.

1:04:21How about the extra dimensions? They come out for free, too. They're forced upon you by the equations. You don't put them in my hand. Not at all. The math does it for you. 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 10 must be zero. Therefore, D must equal 10. That is where the extra dimensions are forced upon you by the equations. Jeez, that's insane. That's pretty cool, though.

1:04:59Yeah. I mean, that's...

1:05:01Neil deGrasse Tyson:So 10 dimensions. Wow. So we don't experience them. Why? Because we believe that they're probably too small for us to see with the naked eye. I don't know what a small dimension means. It means that if you head off in a given direction, you kind of 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 it 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... You're sucking 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.

1:05:38You've hidden the extra dimension. So all the other dimensions are hidden. We think that is one explanation for why we don't see them. Can anything exist in those hidden dimensions? In fact, I was going to call the elegant universe hidden dimensions. That was the title I was playing with back 25 years ago. But anyway, yes, exactly. All right, so you're hiding the dimensions from us. Yes. 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 accused me of perhaps on other things. We're saying, how can we make this theory compatible with what we see?

1:06:16Let's envision that the extra dimensions are really small. Got it.

1:06:20Neil deGrasse Tyson:Okay. So a string is 10 dimensions? A string is living in a 10-dimensional space. Right. 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, where 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. Okay, so that's string theory upped by a dimension. And string theory takes you there. It's not something, again, that you put in by hand.

1:06:54He goes wherever his equations want to tell you. I gotta say, it's pretty fascinating. I need to say, this is a purely mathematical undertaking. It's all driven. Totally. But the beauty of it is, 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 we go to queries, what is the current state of string theory? Current state is... It's health. Yeah, 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.

1:07:31How, you know, if string theory was a student, you know, how would you grade it? And the grades went from B +, I think that may have been Nobel laureate David Gross, I could be getting their grades wrong, to an A +, which was Andy Strauminger, 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 allowance to determine whether it's correct.

1:08:14Neil deGrasse Tyson:And that's almost a violation of one of the most important tenets 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. Theory really should be preserved. That's a more humble. Yeah. But the math makes it a theory. Well, the theory, for a theory to be a bona fide theory, it's got to not only account for what you see. Right. Or in an organized, coherent way. It's got to make predictions that you have verified. Right. You've got to be able to measure it. If you have not predicted, then it's only one half of what's going on.

1:08:51Neil deGrasse Tyson:Yeah. And so we're using the word wrong. And I agree with people who are sticklers on that. Got it. But is that because, and I don't want to sound like a jackass, but what you just explained, I got to say, like, Einstein had it easy. I'm serious. Yeah. 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 it. 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, I mean, how do you get to it? Right. We've had problems, unsolved problems that have lasted much longer than these 40 years in the history of science.

1:09:30Neil deGrasse Tyson:Okay. So it took a long time to understand heat and 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 it some fluid? A fluid? Caloric? They called it caloric that could flow. Do you know where we did most of it? It kind of looks. Well, no, that's the air looking like. The air is a fluid. The air is a fluid. That's not the heat. But go ahead. One of the main centers of experiments for this were cannons. Because you fire cannons, the metal gets hot.

1:10:04Neil deGrasse Tyson:Yeah. So as it got hotter, they'd weigh it to see if it had more heat, if the heat was a thing. Right. If it was like possessing heat. Possessing heat. Possessing heat. Yeah, so we went decades and decades with other issues. 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 because it was so beautiful. All right. So beautiful. Just tell me, speak to me, Brian.

1:10:38Neil deGrasse Tyson:because 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 wormholes. and those wormholes represent the literal fabric that stitches together the universe itself. Yeah, we were definitely talking about this at some point. Where are we on that? Well, it's a beautiful idea. Beautiful. It really comes from Lenny Suskind and Juan Maldicena and a whole army of string theorists who developed these ideas.

1:11:26Neil deGrasse Tyson:He came here, gave a talk, one of our evening talks at the Planetarium. Yeah, he has a wonderful book. Very innovative guy. Yeah, I mean, he's driven physics for decades. So he and Juan Maldicena realized that these quantum entangled particles, which Einstein really, in a sense, predicted in his EPR paper, Einstein, Podolsky, and Rosen in 1935, may be connected to another Einsteinian idea, which he came up with a two months distinct from that first paper, an Einstein-Rosen paper on wormhole. 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.

1:12:17Neil deGrasse Tyson: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, Canadian physicist, realized 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. Okay. I'm going to keep watching that space. That's great.

1:13:06you may have heard the best voice in show business Morgan Freeman talking about a serious and underdiagnosed heart condition that's often missed a TTR cardiac amyloidosis or a TTRCM it's a condition that can greatly disrupt your life with symptoms like severe fatigue fatigue, shortness of breath and carpal tunnel. If left untreated, a TTRCM may become serious, leading to a shorter lifespan. A Truby helps adults with a TTRCM live longer and have fewer hospitalisations due to heart issues, so you can focus more on living for what you love. Tell your doctor if you're pregnant, plan to become pregnant or are breastfeeding, and about the medications you take.

1:13:53The most common side effects were mild and included diarrhea and abdominal pain. If you have a TTRCM, talk to your cardiologist about Atruby and visit atruby.com slash podcast. That's A-T-T-R-U-B-Y dot com slash podcast to learn more. It's time to get busy living. Brought to you by Bridge Bio. This episode of StarTalk is brought to you buy six all-new McCafe drinks at McDonald's. We're talking crafted sodas made with your favorite sodas and topped with velvety cold foam, like a Spriteberry Blast made from Sprite and Blueberry Raspberry syrup. Don't miss the Dirty Dr. Pepper or Orange Dream, too.

1:14:35And there are refreshers made from fruit flavors and add-ins like Popping Boba and Freeze-Dried Dragon Fruit. Try the Blackberry Passion Fruit Refresher, Mango Pineapple Refresher, or Strawberry watermelon refresher with freeze-dried strawberries. Try all new McCafe drinks now at McDonald's. Ever notice that after 30, a couple of drinks can hit harder the next day? That's because it's not just dehydration. Your brain and liver are doing extra work overnight. Cheers Restore is designed to support your body while you sleep. Take it after your last drink or before bed and wake up feeling like yourself.

1:15:14With ingredients like DHM and cysteine, it helps support normal alcohol metabolism and liver function. They offer a feel 50 % better or your money back guarantee. Cheers is backed by doctors, PhDs, and over 1 ,000 verified clinicians, and they've sold over 50 million doses. Take Cheers Restore after your last drink or before going to bed and wake up feeling at least 50 % better or your money back. For a limited time, our listeners are getting 20 % off their entire order by using code STARTALK at cheershealth.com. Just head to cheershealth.com and use code STARTALK for 20 % off. After you purchase, they will ask you where you heard about them.

1:16:01So please support our show and tell them that Chuck sent you. And by that, I mean StarTalk.

1:16:14Neil deGrasse Tyson:It's time for Cosmic Queries. We should have some jingle or something that's, that, or some animation. Some animation would be good. You know, Cosmic 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. Yes. From one of our own producers. Yeah, Tamsin, our producer. Yeah. Our taskmaster. Yeah. Tamsin wants to know this, Brian. If space-time had consciousness and could have a favorite movie, what do you think that movie would be? I think it would be Planet of the Apes. Really? Really. Oh.

1:17:01That scene at the end, you know, with a half-submerged or sunken statue. You blew it up. You can't go out of hell. Damn it. That's it.

1:17:18Neil deGrasse Tyson:Wow. Wow, yeah. Because that played loosey-goosey with space-time. Yeah, it certainly did. To go into the future. It's another Earth that has a different evolutionary path. It was the first time that time travel really meant something to me as a kid. I was like, oh, man, this is crazy. Yeah. That's a good one, man. Planet of the Apes. The original. The original. Forget about the other 75 ,000 follow-ups. Exactly. Return to the planet. Escape from the place. Bride of the Planet of the Apes. Banality of the Planet of the Apes. You know, when I went back and saw that film, it's actually quite deep.

1:17:55Neil deGrasse Tyson:Because the different species of apes had different roles in this society. It's a caste system. It's a caste system. It's a caste system. It's a caste system. Right. So the chimpanzees were the academic class. Right. Because they're close. Why not? Of course. They're our closest cousins. Yeah. And the baboons were like the police. Right. Yeah. Or the gorillas were the police. The gorillas were the police. The orangutans are the elders. No, no. The orangutans were the diplomats. Diplomats. That's correct. Yeah. Yeah. Right. The politicians. It wasn't politicians. It was a caste system. That's right.

1:18:24It's pretty wild. So our first few questions have been previously asked by our Patreon supporters. But you said, I'm going to have to see what Brian says about this. Oh. Right. So they were elevated. So they were elevated. It was above my pay grade right there. So they wrote in with a question, and you were like, let me get my supervisor.

1:18:50Neil deGrasse Tyson:So I punted it. I punted it. Okay. I want you to go. So this is Brian Berg. He says, hey, Dr. Tyson, Lord and Ice. Chuck, you should be able to nail this one. It's Brian from Portugal. Brian, shut up. 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.

1:19:28Ooh, nice.

1:19:30Neil deGrasse Tyson:Now, let me preface that a little more here. Sure, please. 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 gravitational field of the black hole itself, the energy density of the field. So I said, oh, so that's 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 that I was DNA is gone. So no, there's no preservation of information there. And that's what Stephen Hawking said.

1:20:09So when Stephen Hawking did his initial calculations in the 1970s, 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.

1:20:51So if you're saying that, you're saying quantum mechanics is wrong. Okay. And we're not willing to go there.

1:20:57Neil deGrasse Tyson:Yeah, quantum is so successful. Right. You got to be ready for okay to throw out. You got to be somebody more than Stephen Hawking. And this led Lenny Susskind again and Gerard Atuf, who won the Nobel Prize, and various other people to spend 25 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.

1:21:37Now, 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. Preservation. He had a gap with somebody, wasn't it?

1:21:51Neil deGrasse Tyson:Was it with Presco? John Presco? Yeah. He was a postdoc when I was a graduate student at the University of Texas. Okay. Yeah. Yeah. So Presco won the bet then. So Preskill won the bet, but Kip Thorne was also part of this. And Kip Thorne was unwilling to concede. Kip Thorne is in our archives. Check him out. Yeah, absolutely. We interviewed him in his office in Pasadena. So Hawking conceded the bet that John Preskill said the information does come out. And he gave him an encyclopedia of baseball, a lot of information he provided him as the way to. Baseball already has too much information. Now you have an encyclopedia of it.

1:22:27It made good on his bet. I don't know where Kip Thorne stands on this. I don't know that he has conceded. Okay. Okay. What's the business about the information being stored in the event horizon? Have you? Yes. What do you call that? That's the holographic. Holographic idea. And that's part of the solution for why we believe the information comes out. And that's Suskind again. Suskind again. This guy is 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 in.

1:23:01It never went in. Whoa. The imprint was left on the event horizon. Yes. Whoa.

1:23:04Neil deGrasse Tyson:Very cool, man. Super cool, man. Yeah, so we have an explainer on whether or not we're living in a black hole. We could be. Just the properties. Yeah, we could be. If it's big enough, yeah. Yeah, yeah, okay. All right, here we go. This is Rachel. Rachel says - And we're still in questions that 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.

1:23:41Could the force we attribute to dark energy, which is causing the accelerated expansion, actually be explained by a kind of cosmic centrifugal force? So she's thinking that we just on a whirly bird. Whirling dervish. We're in a whirling dervish. We're in a teacup ride. It's hard to see 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 how that would work.

1:24:21Neil deGrasse Tyson: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? Write a paper and we'll see what it works. Yeah, that was, all right, what a great question. Okay, we're going to move into regular questions now. Wait, 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.

1:25:00Neil deGrasse Tyson: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. Let's look at your descending to the singularity. The two quark particle falls. Tidal forces get greater and greater. And then it splits the two quarks. So now it becomes two pairs of quarks as they fall in. Then it becomes 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.

1:25:45Neil deGrasse Tyson:Why doesn't that happen? Well, you do feel tidal forces as you get ever closer to the center for sure. But I'm not a quark. And it's a finite time scale between when you cross the event horizon and you hit the singularity. And 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. 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 black hole. Oh, if they're thinking that an infinite energy transfer, then yeah, absolutely.

1:26:23Everything is finite timescales, finite energies. And so, yeah, exotic processes can certainly happen when the gravitational force is that powerful. Now, of course, when you get to the singularity, we have no idea what actually happens.

1:26:34Neil deGrasse Tyson:Because you street theorists haven't figured it out yet. We have not. But that's actually a real point. 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 accelerated expansion of the universe would get on the scale of nucleons and split apart the quarks. Quark antirquark pairs. And then make another pair and just keep doing that. Yep, yep, yep. I mean, there are many other processes that can happen in the world, so I wouldn't just focus on this. 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 processes.

1:27:12I was just wondering if it just creates a whole universe of quarks. You'd have to sort of calculate the rate at which those processes happen versus other things. I would do that.

1:27:22Neil deGrasse Tyson:It's the entire dark energy universe. Inside you, but we're still inside the black hole? No, no, now we're just looking at the big rip. I'm just wondering, if this keeps happening, it's using up the energy of— But then, of course, if that were the case, it would no longer undergo the accelerated expansion. Exactly. It would fall to expansion. It would fall to expansion. Exactly. Okay. Okay. 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?

1:27:59Well, 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 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 then the unexpected thing is that label, the amount of time between two different locations, can be influenced by the force of gravity.

1:28:38Neil deGrasse Tyson:Right. But that doesn't require that it be a field. Yes, it 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. 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 or physics enthusiasts.

1:29:21All 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. In fact, he drew a picture.

1:29:49Neil deGrasse Tyson:He had a U. With an eyeball. Yeah, yeah. A U, a serifed U. and on one of the upwards of the U, there's an eyeball looking at the other line of the U. Oh, very nice. The universe. Looking at itself. So it's 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 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 today.

1:30:31Neil deGrasse Tyson:Let me ask you about this. But there's some thinking that, and this is wishful thinking, not because someone has researched this, 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, you know, there's an igneous rock. Because 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 what elements do when they're heated for a certain amount of time under pressure. And that repeats depending on the planet. So there are general rules of geology that apply to all planets.

1:31:06Neil deGrasse Tyson: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? Could it be as natural on a planet as rocks are to the geologists? And 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 a sense that it formed relatively quickly on the planet Earth. So it didn't take an enormous amount of time. If it took billions of years, you'd say, whoa, that was some hard stuff. Yeah, it formed in just, in fact, we used to, how long do you think it took?

1:31:43Neil deGrasse Tyson:Half a billion, I'd say. Okay, that's what we used to say. 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. Four and a half billion years. Yeah, yeah. And then the early signs of life were like 3.8, 3.9. So you say 600 million years, we used to say. And then we said, no, no, that's unfair. That's unfair. When Earth formed, 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.

1:32:14Neil deGrasse Tyson:Yeah. Let the earth cool, for goodness sake. So the cooling, you let it cool at about 4 billion years. That's half a billion years. At 4 billion years, now you start the clock, and you have life 200 million years later. Wow. That's really great. Right. In the grand scheme. In the grand scheme. Yeah, so that's what I'm saying. So life is pretty cheap, then. Yeah, it's 5 % of the total time earth has been around. Again, however, 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.

1:32:52So 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 going to turn out, but it's a possibility. It's a possibility.

1:33:05Neil deGrasse Tyson:Well, except that there are amino acids on meteorites. Yeah, we've found them already. An interesting question, though, is the way that proteins are coded 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, in all life. On another planet, if there is other form of life, the deep question will be, is it the same code? Or is it different? It 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 end of it.

1:33:46Neil deGrasse Tyson:That we've not fully explored all the ways of being alive. Exactly. Wow. All right. Well, great question. Way to go, Cody. All right. This is Aaron Bailey, who says, hey, StarTalk. I am Aaron from Florida, and we're sorry. Stop. Stop. Florida's trying. They're trying. All right. Yeah. So Aaron says, long-time viewer, first-time subscriber. Thank you. We appreciate that. According to Einstein's equations, 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 in the first question, yeah, I mean, Einstein's special and general relativity both embrace a certain kind of time travel.

1:34:31And 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.

1:34:41Neil deGrasse Tyson:Famously portrayed in Interstellar. And so if you go to the edge of a black hole and you hang out and then you come back, everyone that you meet is going to 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. Exactly. And you know who they left up in the ship? The black dude. he came back like oh god damn 23 years you know I'm serious now you know I'm on social security I don't get it you go down there you tell me you'll come right back you're worse than my kids you're worse than my kids I don't get it Matthew McConaughey alright what was the second half to that question What was the other half?

1:35:33And 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 of. And so we have these detectors all over the planet trying to capture little particles of dark matter.

1:35:57Neil deGrasse Tyson:If that's the right explanation, we haven't been able to find any of it. You don't do that? What? Okay, you know they're pulsars. Yes. They're rapidly rotating neutron stars. In a very precise way. Extremely precise. Right. And they're across the galaxy. They're not all that many of them. Right. But there's enough to map out the galaxy. So if you precisely know and measure the pulses of these pulsars. Okay. You can track a gravitational wave moving across the galaxy. Yeah. So you're kind of using them like buoys in the ocean. Oh, good analogy there. Beautiful idea. And you don't even need LIGO for that.

1:36:36Neil deGrasse Tyson:You just need high-sensitive, high-precision time detector. 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, Dr. Tyson, Lord Nice, Alex here from Mexico. Oh, I should say Alex. No, Alexander. Alexandro from Mexico. What? Isn't that racist that you assume? I can be racist. I'm black. I don't know if you realize. Okay? The world invented racism for me.

1:37:18Okay. Okay, here we go. From Mexico.

1:37:22Neil deGrasse Tyson:Did I tell you? I was giving a public talk, and I thought I'd say something funny. I was talking about the dinosaurs, and they went extinct by an asteroid that hit the Yucatan Peninsula of Mexico. And I said, but that's not what the dinosaurs called it. Okay? Okay. I thought it'd be 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 fluid dinosaurs. Spanish fluid dinosaurs. Yeah. Okay. All right. Go. And then you had Trumposaurus, who was just like, keep him out. Anyway, I've always been intrigued and confused by the idea of supersymmetry.

1:38:08If 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 in the beautiful Upper West Side. Oh, nice. Oh, look at that. Way to go, Alex, from right up the street. Upper West Side of Manhattan. Yeah, right.

1:38:34Neil deGrasse Tyson:So 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 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 main motivation for supersymmetry is to address exactly the way you framed the question, which is when we study this Higgs particle, this newest addition that we found on July 4, 2012, at least that's where the announcement was.

1:39:19When 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. Look at that.

1:39:57Neil deGrasse Tyson:So how many more particles come along? It doubles it. It really does. For every known particle, there is a partner. Electrons have - A super symmetric particle. Yeah, super symmetric electron. Do we have words for all these particles? Yes, so the electron has the electron. Quarks, squarks. Neutrinos, snootrinos. No. No. Yes. No. Yes. I don't name them. The snootrino, no. Yeah. You know why? Because somebody, when they found it, they were like, ah, neutrinos, neutrinos. And so the big hope, if you would have spoken to me as a graduate student in the 1980s, the big hope and the reason we believe that string theory might be five years away was we expected supersymmetry, which is the super in superstring theory.

1:40:40We thought it would be found. Those particles would be found at the Large Hadron Collider. And they were not found. Wow. And they will never be found. Well, 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're going to need one. Look at that. Well, that is fascinating, though.

1:41:15Okay. Okay, and does the Higgs have the, do we have a name for the other particle? Higgsino. Higgsino. Yeah. I prefer squigs. You won't go with squarks. You might as well go with squigs.

1:41:30Neil deGrasse Tyson:The photon, what's the symbol? Photino. Really? Yeah. Okay. And the W and Z bosons, those are harder Zenos or Winos. Winos. Winos. They get a little bit, yeah. Yeah, that's getting a little funky. And how about the graviton? 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 models have gravity. Yeah. Yeah. But if you include gravity, then there is a version. It's called supergravity, and it comes out of string theory as well, and it's the gravitino. Right. All right. It's from the graviton. Yeah.

1:42:05Right. Okay. All right. All right. Well, way to go there, Alex. So we're still looking for him. Yeah. You're still looking for him. There's no evidence 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. Right, right. And that's, you know, colliders are expensive. And the bigger they are, the more money they cost.

1:42:32Neil deGrasse Tyson:And we had a big one going in our side of the pond. The superconducting super collider in Texas, funded in the 1980s under Reagan. and dug the hole, got all ready, Waxahachie, Texas. It would be three times as powerful, I think, as - About 50 TEV and we have 14 TEV. Yeah, so three times the power of the one that was built in Switzerland. And then early 90s, they zeroed the budget. And they said, oh, there was cost overruns and this sort of thing, but - Oh, some kind of defense thing. We no longer were fighting for our lives. Peace broke out in Europe. The fall of them. Yes. Peace breaks out and all of a sudden it's like, we don't need physicists.

1:43:19Neil deGrasse Tyson:We need this. 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. 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 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 yeah 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, our understanding.

1:44:16Can 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? They don't even interact with themselves. They interact with themselves. Yes, but anything that has energy interacts gravitationally. And these dark matter particles, through indirect quantum processes, do interact with ordinary matter. And that's how these detectors are set up. The universe is accelerating. Or is that the energy? Well, yes. Well, that's the dark energy. That's the energy.

1:44:48Yeah, 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 see any direct benefit that comes out. There's no bricks and mortar. 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. That's going to take you someplace else, right. Okay, gotcha. All right, this is Luke Sr. who says, best regards from Joliet. He says, Dr. Luke Laporta, Ph.D., translation scholar and sinologist. He says, could it be the entanglement phenomenon 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, you know, his word, magical way.

1:45:43In 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. Does it make sense? 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.

1:46:29To them, they don't know the difference. To them, they don't know that they're far apart. 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, affects 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 wormhole.

1:46:57Neil deGrasse Tyson:So I think for so many years, people were imagining wormholes as some kind of ride in a water park. Exactly. You know, even in the movie Contact. Right. Jodie Foster is going through. But no, you just step through. No, you step through. I think it depends on the nature of the wormhole. But yeah, there can be versions where it's effectively stepping from one place to another. Star Trek did it right, though. They had a portal where it looked like a doorway threshold. Sitting on the edge of forever. Sitting on the edge of forever. And that's a wormhole. You step through it and you're already there.

1:47:27There's no ride. There's no, you just step through it and you're already there. And that's another one where they were going to save someone's life. And they decided not to. And they realized they shouldn't. What they're going to change the future. Yes. In fact,

1:47:38Neil deGrasse Tyson:I was talking with Bill and he said that was his favorite episode. Really? Yeah. It's my favorite watching as a viewer. Yeah. For sure. Because it dealt with time travel in a very emotional way. Emotional and unorthodox way. Yeah. And causality is actually addressed. All right. Zachary E says, Yes, 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.

1:48:23Yeah. 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 100, 200, 500, 1 ,000. I don't know that there's a law of physics that prevents that can happen. Now, there is a law of Jesus, I'm bored, that will allow that. The boredom. Can you imagine living 1 ,000 years? Ugh. Oh, kill me. Just thinking about it, I want to die.

1:48:57Neil deGrasse Tyson:So wait, here's something that we did not raise, which was if there's another identical me, is it me? That's the deep question. That is the question. Now that's a consciousness question. And I think the answer to that is yes. No, I think the answer is no. Why? Because we've already kind of done that experiment. They're called twins. No, I'm saying that person has literally your memories, literally your sense of self until something, measurement tap that causes you to be different. From that. Yeah. Yeah. So it's truly you. That's wild. I mean, if I spoke to that version of you, you would adamantly claim, yes, I'm the same guy.

1:49:35That's me. It's me. It's me, damn it. That's funny. Yeah. I don't know what to say. I've never heard you say that before.

1:49:51Neil deGrasse Tyson:So that means we are living forever. The reincarnation are all over this. That's right. Right. Why? Or at least extraordinarily long. Maybe there is some physical law about maybe the proton decays. Right, right. 10 to the 38 years. 10 to 38? Yeah. It's called 10 to the whatever. More than 10 to the 38. Yeah. Yeah, 32. Wow. All right. This is Marcus Ruzon. And Marcus Ruzon says, hello, Neil and Brian. Love the show. I've been wondering something about time and light. If nothing can 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?

1:50:38Is it possible that what we perceive as time is actually just a consequence of us traveling 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. Okay. And in some poetic sense, I agree with what the questioner asks. Yeah. They're saying that if a photon had consciousness, from its perspective, 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.

1:51:26Correct. 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 experience. Precisely. All right. Okay. Well, there you go, Marcus. But thanks for the, you know. I had nothing to add to that.

1:52:02Okay. All right. This is Patrick Dietz. And Patrick says, hello, Dr. Tyson, Dr. Green, Lord Nice, Pat Dietz from Ravanna, 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 for me. It's really rough, but 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?

1:52:47Right. I get this sort of collection of words, but the problem is. Okay, by the way, people, listen, this is why I love scientists, because they know how to call you a dumbass 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. 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. This is Mr. Zoot. And Mr. Zoot says, Dear Star Talkers, Jeffrey here. Pronounce Jeffrey, Chuck.

1:53:37Screw 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? It's 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.

1:54:27Neil deGrasse Tyson:You think it'll be continuous? Yes. So if you have a particle in a box, then the energy levels are quantized, but they are dependent upon the size of the box. Because you're solving the wave equation. You're saving the wave equation in a box. You're expanding the, what's it called? The harmonics. The harmonics of the wave. And the marnics have to die. They have to fit inside the box. But if there's no box, then they could have any wavelength at all, any energy at all. What you're saying is that the energy of a free electron is not quantized. Correct. I did not know that. I've never heard that before.

1:54:57Neil deGrasse Tyson:Now you explained that it's obvious that it could only be that way. That's wild. Wow. That's absolutely wild. Very cool, man. Wow. Great question, Jeffrey. Just to highlight, because you said something important here. So we'll call it a box, but let's look at a tube. Let's look at an organ tube. Okay. Like a pipe organ. Pipe organ. Right. And you can ask, what kind of wave can you set up inside that tube? And it can only hold a wave where the complete wave is there. Right. You can't hold like a half a wave. Half a wave. Right, right. So it sets what the wavelength is. The frequency of the sound, that's the wavelength.

1:55:39Neil deGrasse Tyson:You get that from the wavelength, in each tube. So different tubes have different frequencies that resonate inside of those tubes. 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 them 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 so each atom has a unique spectra. It's really cool. That is excellent. Wow. I learned stuff on this show. It's so great. So did I. I just never thought about free electrons and their energies.

1:56:18Yeah. Okay. This is Brian Nadeau, 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. I'm a huge fan.

1:56:37Neil deGrasse Tyson:Isn't it just assumed that there's a graviton? And that assumption needs to be verified, hopefully. And what's the energy of a graviton relative to the waves that we just detected? Well, the energy, the mass of a graviton, we believe, is zero because gravity also travels at the speed of light. So it's much like a photon in that particular way. And yes, if we could ever really detect a graviton, do experiments with gravitons, scatter gravitons off of each other, then yes, we would learn an enormous amount about general relativity and quantum mechanics. Yeah, but will it help you merge them? Well, our...

1:57:16Because that's a quantum expression of gravity. That's right. In fact, the very existence of a graviton would be the first evidence that gravity is quantized. Wow. And so we're assuming that there is a graviton, but verifying it would be a huge step.

1:57:32Neil deGrasse Tyson:Who was the first to presume that? The idea of the graviton? I don't historically know. But Einstein was the gravitational wave. Yeah. Well, he was a reluctant gravitational wave person. He was really uncertain in 1916 and 1918 about whether they were real. Amazing. Yeah. Yeah. Yeah. So I'm just saying, 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. Yeah. Okay. Mm-hmm. Wow. Okay. That's super cool, man. That's a good question. Who first introduced the very idea of a graviton? I don't know the answer. It feels kind of natural if you're going to...

1:58:16Neil deGrasse Tyson:I'm going to look that one up. Quantum quantify. Yeah. All right. This is Tash Shaw. And Tash says, Dear Dr. Tyson, Dr. Green, Lord Nice, I'm Tash from Orange, Australia. I'm a long time listener so my boyfriend bought me a subscription to Patreon for Christmas Oh nice Very nice, what a nice boyfriend 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 differentiations Yeah. In fact, a proposal that was made a while ago is that at a collider, like the Large Hadron Collider, when you slam protons together, you can calculate and measure how much energy you have before the collision.

1:59:16You can measure how much energy you have after the collision. And if you 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 see why would you presume that and not as what occurred in the first neutrino experiment that's right so it could be some other particle mysterious particle carrying away but there's

1:59:48Neil deGrasse Tyson:the first neutrino they didn't experiment and there was 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 what's up with that? Well, maybe there's another particle. What's up with that? And they say, if there is a particle, it has to be neutral and it has to be very low mass. And the guy who proposed it was Italian. So little neutral one, neutrino. Oh. Like Bambino, little baby. Like Bambino, neutrino. Neutrino. What you got? Check. Let's go to Cosmic Moss. Says, hello, everyone. Love the show and every star you've had on it.

2:00:25You guys are great. I love the way you teach. Please keep the education up. Dr. 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. I don't know that I understand the question. Kind of like matter, antimatter, but the particle is already in existence. And then it's a counterpart that impedes, I guess, the entanglement. It's kind of like. Read the first sentence again. All right. He goes, could theoretically a frequency. All right. So that's the, I guess, his version of the string.

2:01:07Be matched at two points in space by a microparticle. So that's the entanglement. uninhibited by a resistance only to be met by its astrophysical counterpart.

2:01:21Neil deGrasse Tyson:The only counterpart particles are antimatter. That's it. There's no other thing. 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. There's plenty of antimatter made in the center of somebody. Most antimatter in the universe will get annihilated finding matter. Immediately in the center of the sun. The cool part was in one of the Dan Brown stories, the Catholic Church had a vial of antimatter that they carried away.

2:01:54Neil deGrasse Tyson:That's so funny. Dominus' spirit, oh, he's gone.

2:02:05Neil deGrasse Tyson:Physics jokes, people. So, yeah, I don't, it's not quite clear. If it met its, the counterpart, it would annihilate, no matter what else is going on. No matter what else is going on. Yeah, yeah. All right, so here we go. Kenny Watts says this. Hey, Dr. Tyson, Dr. Green. What's up, Lord Nice? Kenny from 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 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 2.7 degree photons they would influence but presumably if you're able to shield your environment.

2:03:17Neil deGrasse Tyson:Yeah, but the shielding would have to be temporary because 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. That's how a thermos works. Yeah, exactly. There's a time with which you do. 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 can't do that. You're not going to do that. It will not happen. Wow. 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.

2:03:58Okay, 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, where you have two metal plates and there's empty space between them.

2:04:20Neil deGrasse Tyson: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 they attract. Yeah. Yeah. Yeah. Brian, you freaky dude.

2:04:48Neil deGrasse Tyson: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. Exactly. 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 2027. It should be out. Get it out in this decade. Yeah, that's the key thing. Okay. Yeah. All right. And this year, we're recording this in 2026. This is the centennial of Edwin Hubble discovering that the Milky Way is not the only galaxy in the universe.

2:05:24Neil deGrasse Tyson:Wow. He discovers that Andromeda is not just a fuzzy spiral sitting within our stars. It's a whole other island universe out there. I love that too. That was 100 years ago. So, 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 pleasure. Chuck and baby. Yes. And we're catching you on YouTube. Were you just smart enough? That's right. On the StarTalk YouTube channel. Were you just smart enough for this conversation?

2:05:59Neil deGrasse Tyson:Today I was the dumbass. And happy to be so. All right. Until next time, Neil deGrasse Tyson, keep looking up.

2:06:34and most of those people maintain skin that's still more clear at one year with monthly dosing.

2:07:04if you have new or worsening eye problems. You should not receive a live vaccine when treated with EBCLIS. Before starting EBCLIS, tell your doctor if you have a parasitic infection.

2:07:11Neil deGrasse Tyson:Ask your doctor about EBCLIS and visit ebglis.lily.com or call 1-800-LILY-RX or 1-800-545-5979. Prime Day is June 23rd through the 26th. These deals are so appealing like portable steamers for steaming. Whoa, did I just sing soprano? I think I'm breaking into song. Shop Epic Deals on air fryers, vacuums, and skincare. I can't stop saying... Shop Epic Deals this Prime Day, June 23rd through the 26th. I think that's it. Nope, there's more. Luggage, smart glasses.