Cosmic Queries – Multiverses & Wormholes with Brian Cox

What properties are fundamental to the universe? On this episode, Neil deGrasse Tyson and comic co-host Chuck Nice take a deep dive into multiverses, inflation theory, wormholes, and quantum entanglement with particle physicist Brian Cox.

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

• 0:01Neil deGrasse Tyson?

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

• 0:14Neil deGrasse Tyson?

  This is StarTalk Cosmic Queries Edition. Of course, I got Chuck Nice with me to make this happen. Chuck?

• 0:21Chuck Nice?

  What's up, Neil?

• 0:22Neil deGrasse Tyson?

  All right, dude. You know, it's not, it's not often we get one of my own people in a Cosmic Queries. That's right. Just my kindred spirit. And today, we've got Professor Hair Doctor Brian Cox across the pond from the UK. Brian, welcome to StarTalk, dude. Not your first rodeo with us.

• 0:41Brian Cox?

  No, it isn't. No, we've been doing this for a few years now. I think it was about 10 years ago.

• 0:45Neil deGrasse Tyson?

  Yeah, yeah. Plus, I've been a guest on your, on your show. A couple of times I've been in the UK. I was there live. You got an audience and stuff. So that, that was fun. And so you, let me get your, make sure I get your bio. So you're a professor of particle physics, University of Manchester. That sounds very specific. It's not, you're not just a professor of physics, right?

• 1:05Brian Cox?

  Yeah.

• 1:05Neil deGrasse Tyson?

  Particle physics.

• 1:06Brian Cox?

  Yeah. I mean, my, my research history is I worked, I've worked at the particle accelerators around the world, actually, including Fermilab in Chicago, the Daisi in Hamburg, and CERN in Geneva. So that's the particle physics.

• 1:18Neil deGrasse Tyson?

  Yeah, the big one, CERN, yeah.

• 1:19Chuck Nice?

  The big one.

• 1:20Neil deGrasse Tyson?

  Yeah, good. And so out of the UK, you've hosted multiple TV shows. The one I remember most is The Universe. And you also did one on the solar system, correct? Correct me if I'm wrong.

• 1:29Brian Cox?

  Yeah, solar system.

• 1:30Neil deGrasse Tyson?

  Yeah.

• 1:30Brian Cox?

  And, uh...

• 1:31Neil deGrasse Tyson?

  Yeah, and you got another one. That was...

• 1:32Chuck Nice?

  That was the local version of that travel show.

• 1:36Brian Cox?

  This is the bit that we might be able to make.

• 1:38Chuck Nice?

  Yeah. The great, the greater travel show was The Universe. And you were like, by the way, check out this neighborhood.

• 1:44Brian Cox?

  We're gonna do multiverses, I think.

• 1:46Neil deGrasse Tyson?

  And you got another one, Brian Cox's Adventures in Space and Time. And for me, what's most important is that you have come stateside, you have crossed, you've crossed the ocean to give a multi-city staged theater tour of the universe. This is, this is bold, hairy, and audacious. I love it.

• 2:11Brian Cox?

  Yeah.

• 2:11Neil deGrasse Tyson?

  I love it. And by the time this posts, you're in the middle of the tour. This, you know, this feels like a little bit, because you got that Beatles haircut. It feels a little bit like the British Invasion, you know?

• 2:22Chuck Nice?

  Oh.

• 2:22Neil deGrasse Tyson?

  Coming across the... You know, taking us, putting us in a new place that we didn't even know we could land.

• 2:28Chuck Nice?

  Nothing wrong with that.

• 2:29Neil deGrasse Tyson?

  Yeah, nothing wrong with that. Very cool. So Chuck, you, you collected questions from our Patreon supporters.

• 2:35Chuck Nice?

  Indeed, we do have them. And of course, you know, our, our listeners very excited to ask Brian questions. So do you want to jump into this?

• 2:46Neil deGrasse Tyson?

  Let's go straight ahead. What do you have?

• 2:48Chuck Nice?

  All right. Here we go.

• 2:49Neil deGrasse Tyson?

  And, and I'm, I'll just shut up this whole time because I got nothing to add. No, if there's a little thing I'll add, Brian, I'll add it. If I'm, not Brian missed something, I'll come in, but otherwise I'm just going to shut up here.

• 3:02Chuck Nice?

  Well, we should, we can, we can take them together, can't we? Because you know, you know, the answer is. Don't worry, Brian. Don't, you ain't got to take that serious for a second.

• 3:12Chuck Nice?

  Or, or. You know, but listen, it's a testament, it's a testament, Neil. Neil is so excited about the universe that he cannot contain himself. And I, I admire that. When anything, which I cannot believe as long as Neil has been an astrophysicist, that he still gets this reaction when something is said. It, you see him go like this.

• 3:40Chuck Nice?

  I know. I'm like, dude, seriously? How long have you been doing this? I know that feeling. I know, isn't it?

• 3:48Neil deGrasse Tyson?

  It's like the, the third grade kid in the front row who knows the answer, but the teacher's not picking on him.

• 3:53Chuck Nice?

  Exactly.

• 3:54Neil deGrasse Tyson?

  Right, right. Okay.

• 3:54Chuck Nice?

  Hey, listen, that's cool though, man. That is, that's, that's awesome.

• 3:58Neil deGrasse Tyson?

  Of course, Brian, if, if we got to do a nerd fight, I'm, you know, I.

• 4:02Chuck Nice?

  Get those lights.

• 4:02Neil deGrasse Tyson?

  I sharpened my nerd, my nerd utensils here, so I'll be ready for you. Okay, Chuck, give it to us.

• 4:08Chuck Nice?

  All right, this is Marcus Gustafson, Gustafson, who says, hello and greetings from Sweden. If the strength of gravity happened to be a little stronger or a little bit weaker than it is.

• 4:26Neil deGrasse Tyson?

  How different would our universe be?

• 4:29Brian Cox?

  It's a good question, and this is widely debated, actually, because there's a question of how much you can change the fundamental properties of nature. So, as you say, the strength of gravity, the mass of the electron, the way the Higgs field works, all those things, such that you have a radically different universe. And actually, it's quite hard, because you can change some things and then change something else, and it kind of balances the change out. And so it's quite a controversial area, actually. But broadly speaking, if gravity were too strong, all else being equal, then things would collapse ultimately into black holes very quickly. So the early universe would not have formed extended structures like galaxies and solar systems,

• 5:12Brian Cox?

  or stars may be very short-lived and so on. So you can change the universe such that you would not have life in the universe if you increase the strength of gravity too much. But also, you can decrease it too much, and then stars and galaxies don't form in the early universe. And again, you probably don't have a living universe. Now, the complication comes when you say, "Okay, well, what if in the early universe, the slightly over-dense regions were a bit denser, which would have something to do with a theory we called inflation, possibly, or something, the way the Big Bang was? And then you turn gravity down a bit? Can you kind of compensate?" And it's true, you can. So it becomes an extremely difficult modeling challenge. And so you'll see research papers on this.

• 5:57Brian Cox?

  How can you change the things and fine-tune things? But broadly speaking, that's what happens. If it is too strong, then everything collapses into black holes. And if it is too weak, nothing forms at all.

• 6:08Neil deGrasse Tyson?

  Okay, so that's the physicist answer, okay? Now we'll give you the astrophysicist answer, okay? Ah. In Graduate Astrophysics 101, okay? One of the first calculations we do is what happens to the luminosity of a star? If you change the gravitational constant, okay? It's a calculation we do, alright? So what you do is you you you put a little parameter there and see what happens to that parameter as you run through the calculations for a star's luminosity. And what you find is that the luminosity of a star is extremely sensitive

• 6:49Neil deGrasse Tyson?

  to the value of Newton's gravitational constant, to the seventh power, okay? So so what's interesting about that is if the gravitational constant were different, slightly higher earlier in the universe than today, as as as Brian can attest, there are whole branches of physics that think about and wonder and worry about whether the constants have actually been constant, alright? But forget whether we can, we have godlike powers to just change it and see what happens. Were they always this good? Did they change over time? So you can look at what, how sensitive it is and constrain how much it could have possibly changed,

• 7:31Neil deGrasse Tyson?

  because you would see stars of enormous luminosities living out their lives very quickly in the early universe, and you don't see that. So it's it's to the seventh power of that term that the luminosity would be affected. And seventh power is is that times that times that times that times that, okay? All through. So we actually find that number in intro astrophysics graduate school.

• 7:58Chuck Nice?

  And can you define luminosity for me? It's not, because if you're saying that it's it's not just brightness.

• 8:03Neil deGrasse Tyson?

  Oh, yeah, yeah, yeah. So here it is, it's simple. This this example is rapidly becoming obsolete. But take a hundred watt light bulb, okay?

• 8:12Chuck Nice?

  Yeah, well, yeah.

• 8:13Neil deGrasse Tyson?

  Okay, what is that, right? Okay, in the old days, there was like these bulbs that got hot.

• 8:17Chuck Nice?

  Okay, now here's what you do first. You dial up your grandmother on a rotary phone.

• 8:24Neil deGrasse Tyson?

  So, so the wattage is its luminosity. So no matter what distance I put it from you, it will always be 100 watt bulb.

• 8:31Chuck Nice?

  Okay, gotcha.

• 8:32Neil deGrasse Tyson?

  As I get it farther away, it gets dimmer and dimmer and dimmer. So that would be its brightness. That's all.

• 8:36Chuck Nice?

  Right. So that's it. So, okay. So you're saying that gravity is like a string on that, on that, uh, on the light itself? Kind of like that would be making it less?

• 8:46Neil deGrasse Tyson?

  No, no, it would be like a knob on it.

• 8:47Chuck Nice?

  Like a knob turning it down?

• 8:49Neil deGrasse Tyson?

  Yeah, yeah.

• 8:49Chuck Nice?

  Thank you, right. So instead of pulling it back, it's turning down the watt. Okay, that's cool, man.

• 8:53Neil deGrasse Tyson?

  It's a dimmer or a thing on the bulb itself.

• 8:55Chuck Nice?

  Yeah. Yeah. Let's make the universe sexy, baby.

• 9:00Chuck Nice?

  Let's dim the lights, hey, you know?

• 9:03Chuck Nice?

  How would you like a little cosmic champagne?

• 9:07Neil deGrasse Tyson?

  Next. Time to go to the next question.

• 9:09Chuck Nice?

  Time to go to the next question.

• 9:10Brian Cox?

  I'm enjoying this.

• 9:13Chuck Nice?

  You like the sexy universe, Brian?

• 9:16Brian Cox?

  I'm gonna use it. I'm making notes. I'm gonna...

• 9:20Chuck Nice?

  All right, let's go to, uh, Sandra Bayani. And Sandra says, "Is it possible that the laws of physics change beyond our cosmic horizon so that all of our theories about multiverses stop working and stop making sense? Greetings, fellow Earthling. I cannot get enough of this show. Please, whatever you do, never stop this podcast."

• 9:46Neil deGrasse Tyson?

  Oh, Chuck, did you just add that?

• 9:48Chuck Nice?

  No, I didn't. I really didn't.

• 9:53Neil deGrasse Tyson?

  Actually, I love that question. I love that question because it brings in our horizon and multiverses and the very theories that predict the multiverse work in our universe. Why should they work in another? We're gonna take a break. And when we come back, we will get right to the heart of that question with our special guest today. He's a special guest to me, Brian Cox from over in the UK. We'll be right back.

• 10:20Speaker 03

  I'm Joel Cherico and I make pottery. You can see my pottery on my website, cosmicmugs.com. Cosmic Mugs, art that lets you taste the universe every day. And I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 10:40Neil deGrasse Tyson?

  We're back, StarTalk, Cosmic Queries. This is everything physics, because I've got one of my people here. One of my, one of my science and education brethren, Brian Cox from over in the UK, who, they call him a rock star over there, and we've said this on his previous appearances, but it's worth repeating, that this man had a number one song on the pop charts in the UK. So you're a literal and figurative rock star of science. Am I, have I overstated that?

• 11:13Brian Cox?

  No, I think you've understated it, if anything.

• 11:15Neil deGrasse Tyson?

  So, what was the name of the song again, that you performed?

• 11:22Brian Cox?

  The most famous song is a song called "Things Can Only Get Better", which you will say correctly is, runs a counter to the second law of thermodynamics, and you'd be right.

• 11:31Neil deGrasse Tyson?

  Oh, yes.

• 11:32Brian Cox?

  So it's an inaccurate song, but, uh, yeah.

• 11:33Neil deGrasse Tyson?

  Yeah, sometimes you gotta break some eggs to make an omelet, you know, as they say. All right, let's keep going. So Chuck, we left off with a brilliant question about, here we are in our universe that has our own horizon, and we come up with our own theories of the universe, and one of them is that there might be a multiverse. So beyond our horizon, if it's not in our universe, why should we even believe that the rules that predict a multiverse would even exist? I love that.

• 11:58Brian Cox?

  So, our horizon, first of all, there is a limit to how far we can see, which is the fact that our universe is of a finite age, or let's say there's been 13.8 billion years since the Big Bang, and so there's a, there's a finite distance you can see because light travels at a finite speed. So, we are very sure that there are galaxies way beyond our horizon, but essentially, the light has not had time to reach us from them. And, now, actually, as Neil said in the answer to the last question, you can ask, you can say, "Well, observationally, do we see any evidence of the laws of nature changing as we look out to the most distant galaxies?" And the answer is no. We have no evidence that they change in the patch of the universe we can see.

• 12:43Brian Cox?

  So that's the observational point. But when you start to talk about the laws of nature in different regions of the universe, our multiverse, as you said, then it becomes more interesting. One multiverse, there are lots of different kinds of multiverse, but one of them is called the inflationary multiverse. So we have a theory called eternal inflation, which essentially leads to the idea that there are perhaps an infinite number of bubble universes, of which ours is one. And the piece that we can see, the observational, the little piece we can observe is a patch in one bubble universe amongst perhaps an infinite number of bubble universes in the inflationary multiverse. And those theories do lend themselves, potentially,

• 13:26Brian Cox?

  to the laws of nature in each bubble possibly being different. And the way I sometimes picture it is like a snowstorm with snowflakes. So every snowflake is different because it's had a different formation history. But there's something similar about them all, which goes to the underlying structure, which is to do with the water molecule itself. So there's something similar, there's an underlying framework, but every snowflake is different. And the inflationary multiverse can be like that. So you can imagine that the laws we see, things like the strength of gravity, sort of crystallize out as these bubble universes form from the potential, which is this thing called inflation that's potentially going on all the time.

• 14:11Brian Cox?

  So it's possible that different universes have different emergent laws, things like the strength of gravity. And I think most physicists probably all expect that there'll be some kind of underlying framework, which could, something that we don't know what it is, right? Something like string theory or something, which underlies the whole thing. So that, maybe Neil wants to add.

• 14:35Neil deGrasse Tyson?

  I love your snowflake analogy, but suppose that...

• 14:40Neil deGrasse Tyson?

  Do you have enough latitude in your eternal inflationary multiverse model to have a universe that has five pointed snowflakes instead of six? I mean, is, how much room do you have to just make stuff up?

• 14:58Brian Cox?

  We don't know. This goes back to, it links to something called the string landscape, which Leonard Susskind actually wrote a great book called The Cosmic Landscape a while ago, detailing this theory. So when you look at string theory, which is-

• 15:09Neil deGrasse Tyson?

  Just remind me, Leonard Susskind is the one who's a big exponent of the holographic universe?

• 15:14Brian Cox?

  Yes.

• 15:14Neil deGrasse Tyson?

  That's the same guy?

• 15:15Brian Cox?

  He's one of the, he's been at the cutting edge of physics for decades, raising it. And then, so in the string landscape, the idea is that in string theory, it turns out you can have, there's a number that they calculate. I don't know how they do it actually, but it's something, well, I do know how they do it. It's something to do with all the extra dimensions being curled up and stuff. It doesn't matter. But essentially 10 to the power 500 different possibilities. So one with 500 naughts after it. These are the different ways that you can produce laws of physics like the ones we see from the underlying theory. And that was seen as a really disappointing-

• 15:53Neil deGrasse Tyson?

  That's a lot of wiggle room right there.

• 15:54Brian Cox?

  Well, but the way I see it, it's almost like saying, we understand DNA. So in biology, we have a theory, we have these things, A, C, T and G, right, the four different bases that come together to form DNA. And it's like saying, okay, so there's an underlying theory. It's pretty simple. It's the double helix, it's chemistry. Out of that, it's like saying, right, predict a human being. So of course-

• 16:18Neil deGrasse Tyson?

  Yeah, you can't do that.

• 16:19Brian Cox?

  You can't, because there are many different combinations of DNA. And we have no understanding yet of which ones would work and which ones wouldn't, and which ones can be realized by evolution and which ones can't, you know, it's just-

• 16:30Neil deGrasse Tyson?

  It's an astronomical number of combinations of just to make humans-

• 16:35Brian Cox?

  Yeah, exactly.

• 16:35Neil deGrasse Tyson?

  Let alone all forms of life.

• 16:36Brian Cox?

  So it's like saying, we understand the basic chemistry that gives us that thing, DNA. But then from that, predicting a particular instance of that, an organism, is of course, it depends on its history, it depends on all sorts of things. And it's the same-

• 16:53Neil deGrasse Tyson?

  However, can you-

• 16:55Chuck Nice?

  If you look at that like, um, I don't know, an alphabet to create a language.

• 17:00Brian Cox?

  Yes.

• 17:01Chuck Nice?

  Can you rule out the nonsense? For instance, if you know English, you know that uh H L P P P five is not a word.

• 17:13Brian Cox?

  Right? There's a grammar.

• 17:14Chuck Nice?

  So are you able to kind of rule out the nonsense that, okay, these things would not happen? And so even though it is a possible combination, we know that it's kind of gibberish. How do we narrow that?

• 17:27Brian Cox?

  Well, I mean, we don't, we don't know. We haven't got the expertise. We don't really know what the underlying theory is. Um, but I mean, for example, you could imagine a bubble universe that forms and gravity is so strong that it just collapses again in a millisecond. There may be many universes like that. So that might be, you know, as you say, that might be a universe that we consider was just never got going. So it's

• 17:52Chuck Nice?

  Gibberish. That's a gibberish universe.

• 17:56Brian Cox?

  Just about form and then collapse again, for example.

• 17:59Chuck Nice?

  Eric, you'll know, you'll know if you meet a life form from there, because there's this like

• 18:10Neil deGrasse Tyson?

  So not only are the laws of physics gibberish, so is their language, right?

• 18:14Chuck Nice?

  Exactly.

• 18:15Brian Cox?

  I just want to emphasize, this is speculative stuff. So the string landscape, I said Lenders Susskind's book is great on this. Uh, and then the link, though, it's interesting, the inflation, which Neil will know about as well. That's a theory that was introduced initially just to um deal with something called the horizon problem. You mentioned the horizon. It's essentially the the unexplained point that if you look out, look in one direction out into the universe as far as you can, and then turn around and look in the other direction. Then you're looking at points that emitted light that we're receiving now. That now in the universe is something like 93 billion, I think it is light years away, right?

• 18:54Neil deGrasse Tyson?

  Yeah, it's around there.

• 18:55Brian Cox?

  So you're looking at points that in the standard model of things could never have been in contact with each other. And yet are at the same temperature to one part in a hundred thousand, which is an observation. So that means inflation was initially

• 19:09Neil deGrasse Tyson?

  Just a quick thing, Chuck, I think we did an explainer on this. Uh, there was something where I was talking about That the universe has a more uniform temperature than different parts of the same room you're in.

• 19:21Brian Cox?

  Yeah.

• 19:22Chuck Nice?

  Right. Well, that's because we were, with that explainer, we were talking about red shifting is kind of how we got into.

• 19:28Neil deGrasse Tyson?

  Oh, that's how we got there because I was saying you have an air conditioner in a corner, you have a heater over there and you're fine if it's a five degree range in a room that's talking to itself thermodynamically. And now we have across the whole frickin' universe and it's within a hundred thousandth of a degree.

• 19:43Brian Cox?

  Yeah.

• 19:43Neil deGrasse Tyson?

  Which is completely mind boggling freaky and we needed a freaky explanation.

• 19:47Brian Cox?

  So inflation was the idea that once upon a time they were in contact and then the universe expanded very, very, very, very fast for probably a small amount of time. And so, and so we thought that they couldn't have been in contact with each other, but in fact they were. And so that's why inflation was introduced. But it ended up.

• 20:07Chuck Nice?

  Interesting.

• 20:08Brian Cox?

  It ended up doing several things that it was not designed to do initially. One was that the thing that drives inflation, which has got a fancy name called inflaton field, but it doesn't matter.

• 20:18Chuck Nice?

  Oh, it's, it's, it's a, it's a breakdown in the supply chain.

• 20:21Neil deGrasse Tyson?

  Inflation.

• 20:22Brian Cox?

  Oh, it makes that look trivial. Two, two points were doubling in, if you take the two points in the universe, then they double, the distance between them doubled every 10 to the minus 37 seconds in the basic models of inflation. So it's much worse than we're going through now with prices. It's an exponential expansion. But in.

• 20:44Neil deGrasse Tyson?

  Much worse is an understatement there, just to be clear.

• 20:46Brian Cox?

  But in looking at that, Stephen Hawking actually was involved in this and many physicists in the eighties found that these theories.

• 20:55Neil deGrasse Tyson?

  Wait just a sec, Chuck, Chuck, last time we did this, he said Stephen was involved in this.

• 20:59Chuck Nice?

  I know, yeah, he's cleaning it up this time.

• 21:02Neil deGrasse Tyson?

  He's, he's, he's been a little better.

• 21:06Neil deGrasse Tyson?

  We got to hear the last name here.

• 21:09Neil deGrasse Tyson?

  This time.

• 21:10Brian Cox?

  So that that theory, it was discovered, predicted that there would be ripples in the density of particles in the universe through the big bang as inflation drew to a close, which are the ripples that we see in the cosmic microwave background radiation, which you may have talked about, and also actually in the distribution of galaxies across the sky. So there's a distribution, they're not just completely random across the sky. There are patterns in the galactic distribution. And that was predicted before it was observed by this theory. So the theory is interesting and textbook, but you'll find it in cosmology textbooks. But the eternal inflation bit, which is kind of an add on to that, ends up with this idea that inflation doesn't stop everywhere at the same time, basically.

• 21:54Brian Cox?

  So you get multiple bubble universes. And then that theory was noticed that that's a mechanism to realize the string landscape, which gives you the possibility of varying the laws of nature in each of those bubbles. So that was a history. So it's not just, it sounds fantastical, but it's not just like somebody just dreamt it up one day and said, this would be.

• 22:13Neil deGrasse Tyson?

  Right, right. I try to make that clear because otherwise they think we're just pulling stuff out of our ass. And it's, it's, even if it is out of our ass, it's very carefully withdrawn.

• 22:23Chuck Nice?

  By the way, that's, that's one of the universes.

• 22:31Neil deGrasse Tyson?

  With a central black hole. Yes. Time to go to the next question.

• 22:34Brian Cox?

  Yeah, really.

• 22:35Neil deGrasse Tyson?

  Time to go to the next question.

• 22:37Chuck Nice?

  Okay. Love it.

• 22:40Chuck Nice?

  Okay, here we go. Kitty Wegmans says this, hello, Dr. Tyson, Dr. Cox and Lord Nice. And I bet you can't pronounce my name correctly. I, I, you win that bet.

• 22:57Chuck Nice?

  Get no argument from me.

• 23:00Neil deGrasse Tyson?

  And the name is what?

• 23:01Chuck Nice?

  I was asking.

• 23:02Neil deGrasse Tyson?

  What's the name?

• 23:02Chuck Nice?

  His name is H I D D E.

• 23:06Chuck Nice?

  W A A G E M A N S. I said Hiddie Wegmans.

• 23:11Neil deGrasse Tyson?

  Okay.

• 23:12Chuck Nice?

  And he's from the Netherlands, so.

• 23:14Neil deGrasse Tyson?

  Oh, that helps how to pronounce that, yeah. Hiddie Wegmans, maybe, maybe.

• 23:19Chuck Nice?

  Hiddie Wegmans, okay. And yes, it's, yeah, if it's Dutch, it's.

• 23:25Chuck Nice?

  He says, I'm asking myself after I watched the movie The Atom Project, if you really can time travel with wormholes. By the way, oh, here we go. Chuck Hiddie is pronounced hidden without the N. Who knew?

• 23:44Neil deGrasse Tyson?

  Hiddie.

• 23:44Chuck Nice?

  There you go.

• 23:44Neil deGrasse Tyson?

  Hiddie.

• 23:45Brian Cox?

  Wormholes.

• 23:45Neil deGrasse Tyson?

  You gotta read to the end so he can help you pronounce it.

• 23:48Chuck Nice?

  I, listen, that is, that is too much work, Neil.

• 23:56Neil deGrasse Tyson?

  All right, so, so Brian, we're talking about time travel and wormholes. I presume, I think everyone knows with Einstein relativity, you can travel into a future, all right? Or at least into the future of where you once were. So let's confine this to can you go backwards in time? Do wormholes enable this at all?

• 24:14Brian Cox?

  Wormholes are getting increasingly interesting, actually, particularly in the study of black holes. We can get on to that. But, so yes, wormholes are allowed geometries in Einstein's theory general relativity. If you just take that theory alone. What do I mean by that? So they really are shortcuts through space and time. So you could imagine, you know, traveling from New York to Sydney, it takes a long time, you go around the surface of the earth, or you could tunnel through and you could get there quicker. So, so yes, if wormholes exist and you could travel through them and they were big enough and stable enough. Then you can build a time machine. And now virtually every physicist who works on this, and Kit Thoron actually,

• 24:58Brian Cox?

  who got Nobel Prize for gravitational waves, did quite a lot of interesting work on this. And it it looks like when you bring

• 25:04Neil deGrasse Tyson?

  And he was a main advisor in the movie

• 25:06Brian Cox?

  He was, yeah.

• 25:07Neil deGrasse Tyson?

  He was in fact an executive producer.

• 25:08Brian Cox?

  Which has a wormhole.

• 25:09Neil deGrasse Tyson?

  And the robot in that movie was named Kit.

• 25:10Brian Cox?

  It was, and it has a wormhole.

• 25:12Neil deGrasse Tyson?

  If anybody noticed that.

• 25:13Brian Cox?

  So and he also actually suggested to Carl Sagan in Contact that wormholes were used in the film.

• 25:19Neil deGrasse Tyson?

  In the movie Contact, yeah. Good story, in the story.

• 25:22Brian Cox?

  So so that when you add quantum mechanics into the mix, which is the theory of everything else, because our universe hasn't just got gravity in it, it's got all sorts of other things in it as well, obviously atoms and electromagnetic radiation and so on, then it seems like the wormholes are inherently unstable, the big ones. And if you try to travel through one, it collapses. And they they were called Einstein Rosen bridges before they were wormholes. And they're they're built into the basic description of a of a black hole. If the black hole had listed that it lives forever, it's called the it's the maximally extended Schwarzschild metric, right, whatever it's called. But it was that which was discovered by Schwarzschild in 1916, just after the theory was published, then there's a wormhole in there, right?

• 26:05Brian Cox?

  So they're just fundamental to the theory. But most physicists believe, and Stephen Hawking wrote a paper actually called the chronology protection conjecture, conjecture, where he thought about this.

• 26:15Neil deGrasse Tyson?

  Oh.

• 26:16Brian Cox?

  That that

• 26:16Neil deGrasse Tyson?

  Who knew he was a rapper?

• 26:18Brian Cox?

  Yeah. Chronology, I can't even say it, you can say it, I can't say it, chronology protection conjecture. And but that that these things would not be stable and you can't travel through them, so you can't build time machines. However, it's worth saying that wormholes are becoming very, very fashionable now in what's called the ER equals EPR paradigm. So Einstein Rosen, ER is Einstein Rosen, this thing from the 1930s where Einstein and Rosen noticed that they these geometries exist in spacetime or can exist. EPR is Einstein Podolsky and Rosen spooky action at a distance. It's quantum entanglement. And so what now is very fashionable and looks is it's one of the best explanations

• 27:00Brian Cox?

  of how information gets out of a black hole is that this plays a role. So you can, there's a kind of a dual description. So we've got quantum entanglement, which is this spooky action at a distance thing where you separate things to large distances and they're still linked in some way. And the linked in some way is starting to look possibly like you can describe that in terms of wormholes, microscopic wormholes linking them together. But this is really, this is stuff that's been done now, 2020, 2022. So it's, it's on the edge, but people are taking it very seriously.

• 27:31Neil deGrasse Tyson?

  Okay. So wait, let's, let's pause there and come back. But all right. Now you've established that we agree, we can think about wormholes, but you haven't told us how to go backwards in time. When we come back, Brian Cox is going to tell you how to go back and not kill your parents. Okay.

• 27:46Chuck Nice?

  And I could tell you an even simpler way. If you really want to go backwards in time, get married and do something wrong, because she will never let you forget.

• 27:55Neil deGrasse Tyson?

  Thank you, Chuck, for your marital, splitting your marital issues into this podcast. Startalk will return with Brian Cox. We're going to find out how to go back in time. Be there.

• 28:15Neil deGrasse Tyson?

  We're back. Startalk, Cosmic Queries. Got Chuck, of course, and Brian Cox, my friend and colleague from the UK is taking the United States by storm and a little bit of Canada in dozens of cities. He's bringing his major theatrical production of, do you give it a title? Or is it just everything you want to know about where we are in the universe? How about that? Is that the title?

• 28:41Brian Cox?

  Horizons.

• 28:42Neil deGrasse Tyson?

  Horizons. There it is. And Brian Cox, you can find his schedule in briancoxlive.co.uk. Just do a Google on Brian Cox Live, it'll send you there and you can see the whole schedule. And he's coming through town with a hugely visually spectacular display. And this is what, you know, This is what stages are for. If the universe is the biggest stage of them all, he's brought the universe onto into theaters. So Brian, welcome to town for this. So we left off with describing wormholes, and I have to tell the story. Just I have, Brian, I have to tell this, okay? Chuck, so Brian, you just stay on the side while I tell this to Chuck. So Chuck, I'm in the, I'm in London, and I'm a guest on Brian's show.

• 29:27Neil deGrasse Tyson?

  And we're talking about space travel and space exploration. And, and he's got a whole audience there, all UK people, okay? And they're kind of, they're new to me and I'm a little new to them, but they know Brian. But, and they know I'm American. So I talk about the future of space travel. And I say, maybe, you know, no, chemical rockets are not going to work. In order to do this, we need like warp drives or ideally wormholes. And then we can do this. And Brian kicks in and said, wormholes are unstable and they'll collapse and you can't do this. He's correct, but that's not the point. The point was the audience, do you remember what the audience said? The audience said, that's why the Americans discover everything.

• 30:04Brian Cox?

  Yeah.

• 30:06Neil deGrasse Tyson?

  They're so optimistic about everything. That's why they went to the moon and we're stuck here in London. And so you lost your audience on that comment, Brian.

• 30:16Brian Cox?

  It's true.

• 30:16Neil deGrasse Tyson?

  And I had him from that.

• 30:18Brian Cox?

  That's true, that's true.

• 30:18Neil deGrasse Tyson?

  Because they liked my American, and some of it is just me, but then I realized a lot of it is just American enthusiasm. So, so Brian, how do you use wormholes to actually travel backwards in time? Is that possible?

• 30:29Brian Cox?

  Well, so, yeah, if, if, if they were stable, or you could stabilize them in some way, then you could use them as time machines. And, and that's considered to be unlikely. But it really is true to say that we, well, it's very true to say we don't have what's called the quantum theory of gravity. So we don't really. In any sense, understand the the deep merger between relativism and quantum mechanics, which you need to understand to answer that question. And many physicists point out that we don't, you know, it feels like it's no way to build a universe. I mean, we're all aware of Back to the Future. We've all seen Back to the Future.

• 31:12Brian Cox?

  We all know the paradoxes that happen if you if time travel is a reality. So so I think if you pushed most physicists and said, don't be formal about it and don't say what I just said, which is we don't understand quantum gravity yet. And then most physicists would say, OK, we think the laws of nature will be such that there aren't stable, macroscopic, big wormholes. And that's what I think most physicists would say. So you could have a universe which permitted time travel and was not full of contradictions if there were no free will at all. So the whole universe itself is completely consistent and the time travel is built into the consistency. So that's and that's actually what you see in Interstellar.

• 31:57Brian Cox?

  So that that happens in the plot of Interstellar. He can't stop it. I'm not spoilers, you know, but he can't stop himself leaving his daughter's room in the past.

• 32:06Neil deGrasse Tyson?

  And by the way, that's that's also what happened in the story Slaughterhouse Five by Kurt Vonnegut, which is a time travel story on top of being a World War Two story. But his as and I think Kurt Vonnegut got it right. Correct me if I'm wrong, Brian. He just described your life is always there. You're always being born, you're always dying, you're always in school, you're always in love, and you just rejoin where you were on that timeline and relive that.

• 32:32Brian Cox?

  Kip Thorne's birthday party, there's a proceeding. So Neil, when we go to scientific conferences, you have a proceedings. It's a big thing. And Stephen Hawking gave a talk and it's written up in the proceedings of his birthday party because he's so eminent. And Stephen said, said that Kip has become increasingly interested in time travel through wormholes as he's got older. That's how he starts it.

• 33:01Neil deGrasse Tyson?

  That's good.

• 33:04Neil deGrasse Tyson?

  That's good. That's good. I check what this is our third of three segments. Give me, give me a few, see if you can slip in a few more questions here.

• 33:12Chuck Nice?

  All right, here we go. This is Catherine Chellarini Moore, who says, Dr. Tyson, Dr. Cox, Lord Nice, hoping that you can hear Dr. Cox elaborate on he alluded to in his YouTube video regarding time and space not being the stuff from which everything else is derived, rather that time and space may be derivative of something much bigger, much deeper.

• 33:37Brian Cox?

  This comes from the, the study of black holes primarily. And the, I would say it's fair to say the cutting edge as of now is that it looks like space and time emerge from quantum entanglement. So we mentioned entanglement before. I should say what it is, by the way. Shall I say what it is?

• 33:56Neil deGrasse Tyson?

  Sure, sure, sure.

• 33:57Brian Cox?

  So imagine you have a coin and you can toss it and it can come up heads and tails. If it was a quantum coin and there's two of them, they can be in what we call a state such that you could separate these coins out across the Milky Way to the edges of the universe. And you just look at one of them and you could toss it and it would be heads and tails. You can look at it and it's heads. You look at it again, it's tails. Fifty percent of the time looks completely normal. But actually, if you got back together after doing lots of experiments on this thing, you would find that the coins never came up heads at the same time or tails at the same time. They're always heads, tails, plus tails, heads, or heads, tails, or tails, heads. Right. They're always opposite.

• 34:41Brian Cox?

  So you can build a quantum state like that. That's called entanglement. So it's an interesting thing. It's kind of, it's like the information, all the information contained in this system of two coins is somehow spread between them and they don't behave as individual entities, even if you separate them to vast distances. So that's entanglement.

• 35:01Neil deGrasse Tyson?

  Because they're not just coins, they're also waves? And the waves know about each other outside of the local place where the coin is getting flipped?

• 35:09Brian Cox?

  No, it's, it's.

• 35:10Neil deGrasse Tyson?

  If that's the truth, then I've been saying it wrong all these years.

• 35:12Brian Cox?

  No, they, they, really, they are, the best way to consider it is it's a, it's a single system. And the the information, the structure of the system is is a proxy of the whole thing.

• 35:23Neil deGrasse Tyson?

  Why isn't that the wave function? That's gotta be the way.

• 35:26Brian Cox?

  Oh, it is the way, yeah. So so you can write.

• 35:28Neil deGrasse Tyson?

  Oh, that's what I'm trying to say.

• 35:29Brian Cox?

  The wave function, you'd write it down. It'd be a heads tails plus tails heads is an example of a wave function. And for the for the geeks there, we can have a one over root two there in front of each one, everyone equal probabilities. But. You've gone too far, Brian.

• 35:45Brian Cox?

  You had me at wave, you lost me at one over root whatever. It is equal. So you can have lots of different. So that's an entangled system. And.

• 35:55Neil deGrasse Tyson?

  No, wait. Deep in there is that the the there is a term that's squared in the wave function. So he's got to put the square root of two, so that when you square that, it's becomes a half.

• 36:04Brian Cox?

  Yeah, if I want the fifty fifty thing.

• 36:06Neil deGrasse Tyson?

  Yeah, there was a missing piece of what he was saying there.

• 36:09Brian Cox?

  It's the amplitude.

• 36:09Neil deGrasse Tyson?

  Go ahead.

• 36:10Brian Cox?

  But so so that's entanglement. It's it's a fundamentally quantum mechanical thing. And it's very well understood, and we use it in technology and quantum cryptography and so on. So it's a thing. This is how the universe works. And it does seem as if. And as I mentioned before, the idea that you can also interpret that as having wormholes connecting these things together.

• 36:31Neil deGrasse Tyson?

  I love it.

• 36:32Brian Cox?

  Essentially, what you're seeing is that entanglement and space are intimately related. And that's the the modern way of looking at this, the very modern way. And I I I think it's fair to say that most physicists would say that the entanglement is the fundamental thing. And so we're we're beginning to think now that you have a theory of quantum mechanics, quantum field theories. And on some surface or something, and then the entanglement actually produces the space. I mean, it's true to say that entanglement, I've seen it said, which is a beautiful thing to say, that entanglement is sort of the glue that keeps space together. And so entanglement is seems is fundamentally related to space.

• 37:17Brian Cox?

  And time, but it's more obscure.

• 37:21Neil deGrasse Tyson?

  So that's the next sci-fi frontier, because the latest Doctor Strange is madness through the multiverse or something. So they got the multiverse in there, and he's opening up portals, which are basically wormholes, as he, you know, jiggles his hand. So now we've got to somehow get down into the very fabric of the space and time itself. That would be good. All right. Chuck, we've got just a couple minutes. See if we can go into like lightning mode, lightning round.

• 37:48Chuck Nice?

  Okay, if we can. Well, let's lighten things up here with Lindhal Frees, who says, "Doctor Tyson, Doctor Cox, Chuck, here is, is there a perimeter edge of the universe? And where in relation to that edge is the Earth or the Milky Way located? Are we closer or farther to the center of the universe? Also, how do we know the universe is expanding? And is it just that our instruments are getting stronger?"

• 38:14Neil deGrasse Tyson?

  Okay, so we need that in a sound bite.

• 38:18Brian Cox?

  So, no, we're not at the center of the universe. We're at the center of the observable universe, because that's just a piece that we can see. But the universe extends way beyond that horizon. And so it could be infinite in extent. We don't know. But it's much bigger, I think, than the piece we can see. So no, we're not at the center of the universe. It might be an infinite universe. And we know it's expanding, just very simply, because we look at light from distant objects, and that light is stretched. And the explanation is that light is a wave, and it's traveling through expanding space. And so it gets stretched as it journeys. And the basic observation, all the way back to Hubble, is that the further away you see...

• 38:58Neil deGrasse Tyson?

  Hubble, the person, the person.

• 39:01Brian Cox?

  The further away the thing is, the more the light is stretched when it reaches us. And that's what you would expect if space were expanding. Essentially, a uniform rate. It's actually changing a bit. It's expanding a bit faster then.

• 39:13Neil deGrasse Tyson?

  Okay, so there is no, so if we went, if you said, I want to go to my horizon. Let's, Chuck, let's leave tomorrow. So what would we see?

• 39:22Brian Cox?

  Well, you'd see the same universe as far as we know. So you could go to the horizon. And look around and you'd see a completely uniform universe with the same kind of distribution of galaxies.

• 39:34Neil deGrasse Tyson?

  So it's like a ship at sea, it's carrying its horizon with it.

• 39:37Brian Cox?

  Yeah, so yes, that's a good example. If you go to the horizon on your boat and go to the horizon 20 miles away, whatever it is, and then I probably got that number wrong. And now the flat earth people will go, see, didn't know, because, but there is a horizon, whatever it is.

• 39:52Neil deGrasse Tyson?

  It's way closer than 20 miles unless you're in a crow's nest.

• 39:55Brian Cox?

  Yeah, so you go to the horizon and you just see ocean and you go to the next horizon and you just see ocean. And that's what the universe is like as far as we can tell. Minus the fish.

• 40:05Chuck Nice?

  I mean, that's as simple as going to the top of a hill. You experience that any time, like you're driving up a hill or on a bike, you look at the top of the hill and it just looks like that's the end. You get at the top of the hill and it's just more of the same. It's just this time you're looking down. That's cool.

• 40:20Neil deGrasse Tyson?

  All right.

• 40:20Chuck Nice?

  All right, let's go to Elaine Bredor.

• 40:24Neil deGrasse Tyson?

  This might be the last question we have time for. Okay, go.

• 40:27Chuck Nice?

  Elaine says this, hey Neil, Chuck and Professor Cox, we have electron microscopes to probe smaller stuff than with regular light microscopes. Do you think somebody is going to come up with a quark microscope or something of that nature that will enable us to see even smaller or get closer to those strings that theorists fantasize about? Wow, Elaine.

• 40:57Neil deGrasse Tyson?

  Let me just set that up just real quick. So regular microscopes use visible light? And visible light has certain wavelengths. So if you really think about it, a visible light telescope can't see anything smaller than the wavelength of light you're using. Because the light would just wash over it and wouldn't be able to bring it into focus. So electron microscopes use, basically, I think, Brian, is it X-rays? Because electrons and X-rays are the same thing at certain, you can, you can beam electrons to have an energy level of that of an X-ray, and X-rays has really small wavelengths. So now you can see detail way smaller than visible light. So this questioner knows this about electron microscopes and wants to take it another step.

• 41:41Brian Cox?

  And there's a really great fundamental point to make here, which goes to black hole physics, actually, again. Is that, so as you make, if you, if you take the wavelength down, quantum mechanics allows you to think of light as a wave or as a stream of particles called photons. And as you shrink the wavelength, the energy of the photon goes up. So that's just basic quantum mechanics. So the smaller the wavelength, the higher the energy. So you get to a point where if you want to probe smaller and smaller distances, what actually happens is you make a black hole. Because you put so much energy into the small piece of space that a black hole forms. And then as you put more energy in, the black hole grows. And so, so you end up reversing that process.

• 42:24Brian Cox?

  Because, because as the black hole grows, then you get less and less resolution again. So there's a limit to how small you can see.

• 42:33Neil deGrasse Tyson?

  So I'll step in here, because Chuck didn't. You kept talking after you said, yeah, first you make the black hole, and then you continue.

• 42:41Brian Cox?

  You put more and more energy in.

• 42:44Neil deGrasse Tyson?

  I'm saying this sounds dangerous, Brian.

• 42:47Brian Cox?

  It's an in-principle argument, right?

• 42:49Neil deGrasse Tyson?

  In-principle? Oh, it's a thought experiment.

• 42:52Brian Cox?

  The point is that you get to a point where if you try to cram more and more energy into a smaller and smaller amount of space, which you have to do to see the small thing, you have to get more energy in, right, the smaller wavelength, then you-

• 43:03Neil deGrasse Tyson?

  Because you're using photons that are higher and higher energy.

• 43:06Brian Cox?

  Yes, or anything, electrons or whatever it is. Then, then you form, there comes a point where you form a black hole. In that region. And then you.

• 43:14Chuck Nice?

  And then you can't see anything because your microscope got sucked in.

• 43:17Neil deGrasse Tyson?

  Because you daved.

• 43:20Brian Cox?

  You'll have less resolution. So, so, so it's called, now Leonard Susskind writes about it and it's called.

• 43:26Neil deGrasse Tyson?

  Well, so ignoring the complication that you'd be dead and ignoring the complication that you'd be dead and you've destroyed the earth, you'd have less resolution.

• 43:34Brian Cox?

  No, you wouldn't because if you had a tiny mind, tiny black hole, so you wouldn't, you wouldn't notice it, except you'd stop seeing. So you can't probe smaller and smaller distances forever. I think Susskind calls it the UVIR connection, ultraviolet infrared connection. I think that's what he calls it. So, um, but it, but it's a fundamental property of the universe. So black holes stop you from doing that, going to smaller and smaller and smaller and smaller distances.

• 43:59Neil deGrasse Tyson?

  Those pesky black holes.

• 44:01Brian Cox?

  And again, it's fundamental. It's, it's, it's pointing to fundamental physics. So we go all the way back to this idea of space and time and the link to quantum.

• 44:09Neil deGrasse Tyson?

  Right, right. Dude, we gotta wrap it up there. Oh my gosh, did we cover the universe here? Whoa, whoa. Uh, I know you're active on Twitter. Where, where else are you active? Cause you're Prof Brian Cox on Twitter.

• 44:22Brian Cox?

  At Prof Brian Cox.

• 44:23Neil deGrasse Tyson?

  Uh, where else are you?

• 44:24Brian Cox?

  I'm on Facebook as well. Um, but, um, Twi- Twitter's my usual mode of, mode of communication. I don't know why. So just a habit, I suppose.

• 44:34Neil deGrasse Tyson?

  Yeah, yeah, it's a habit. It's quick and, and quick and easy and, and, and sharp. And so, uh, so it's been a delight to have you on this cosmic queries on this, his British invasion of North America. So you're nice.

• 44:48Chuck Nice?

  The Brian is coming, the Brian is coming.

• 44:50Neil deGrasse Tyson?

  Brian is coming, uh, bringing his horizons tour through multiple cities. Check it out, bryancoxlive.co.uk. Brian, always great to see you and hear from you and we'll connect again. Chuck, love you, man.

• 45:04Chuck Nice?

  Love you too.

• 45:05Neil deGrasse Tyson?

  All right. Neil deGrasse Tyson here, your personal astrophysicist. As always, keep looking up.