Cosmic Queries – Theoretical Physics

Neil deGrasse Tyson, comic co-host Chuck Nice, and astrophysicist Janna Levin, PhD, answer fan-submitted Cosmic Queries on theoretical physics: black holes, quantum entanglement, energy, dark matter and a lot more!

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.

• 0:15Neil deGrasse Tyson?

  This is StarTalk. I'm Neil deGrasse Tyson, your personal astrophysicist, and today is a cosmic queries edition. Theoretical physics.

• 0:28Neil deGrasse Tyson?

  Chuck, always good to have you. Hey, always good to be here, Neil. I mean theoretically. Theoretically.

• 0:35Neil deGrasse Tyson?

  This is StarTalk in the Corona-verse. Yeah. You're sitting there in, I guess, in your Jersey home, is that right? That is correct, sir. I am the Sarah Palin of New Jersey. I can see New York from my house. And I'm in an undisclosed location somewhere. Uh huh. Some government underground bunker?

• 0:59Neil deGrasse Tyson?

  So theoretical physics, I know probably 10% of what I should to cover this myself. So we gotta bring in the big brains for this. That takes us to our close friend of StarTalk, physicist, cosmologist, Janna Levin. Jana!

• 1:16Janna Levin?

  Hey, man!

• 1:18Neil deGrasse Tyson?

  Welcome back!

• 1:19Janna Levin?

  Good to see you through the ether.

• 1:21Neil deGrasse Tyson?

  Through the ether, yeah. So get your title straight again. Professor of Physics and Astronomy at Barnard College. Why, does that mean you get double income for that?

• 1:33Janna Levin?

  Oh yeah, oh yeah. Oh no, that's a good, but I should bring that to the provost, right? Yeah. No, I mean, we, you know, we're pretty, we're pretty fluid in our subject matter.

• 1:43Neil deGrasse Tyson?

  Okay.

• 1:43Janna Levin?

  We can move around.

• 1:45Neil deGrasse Tyson?

  What it was that perhaps the subject should have never been divided in the first place?

• 1:50Janna Levin?

  Well, that's a good point, for sure. And, but that's in fact, an interesting point that even, as you well know, Neil, the word scientist is fairly modern.

• 1:59Neil deGrasse Tyson?

  Yeah.

• 1:59Janna Levin?

  Like even the idea of separating science from other... Forms of thinking about the world or meditating on the world is fairly recent.

• 2:07Neil deGrasse Tyson?

  Yeah, I think that we all used to just be called natural philosophers.

• 2:10Janna Levin?

  Absolutely, yeah.

• 2:12Neil deGrasse Tyson?

  Very.

• 2:12Chuck Nice?

  Actually, I'm gonna go with scientists is better.

• 2:16Janna Levin?

  Yeah, you like it better?

• 2:18Chuck Nice?

  I'm just saying, natural philosopher sounds like a BS artist. Yeah, I mean, I'm just saying, you know, so what do you do for a living? Oh, I'm a natural philosopher. Oh, a BSer.

• 2:32Neil deGrasse Tyson?

  Oh, no, you're unemployed.

• 2:34Chuck Nice?

  There you go, unemployed.

• 2:38Neil deGrasse Tyson?

  Chuck, you got the questions.

• 2:40Chuck Nice?

  I do, indeed, as usual.

• 2:42Neil deGrasse Tyson?

  Actually, I want to lead off with a question. Janet, we did a, we did a special Patreon Q and A a few days ago, and I don't know if it's posted yet. But I answered a question, and when I finished giving the answer, I don't, I was disappointed in my answer. And I just thought maybe you could come give me backup on this.

• 3:01Janna Levin?

  All right.

• 3:02Neil deGrasse Tyson?

  Right? So the question was, as we know, if you've fallen towards a black hole, if you observe that phenomenon, it will slow down. And it, in fact, will appear to stop just outside the event horizon. And so, whereas if you are that, thank you, Chuck.

• 3:24Janna Levin?

  Chuck, yeah, Chuck's moving real slow right now.

• 3:30Neil deGrasse Tyson?

  So if, and so whereas if you are the person falling, it just happens in real time to you. You don't think about it at all.

• 3:37Janna Levin?

  Yeah.

• 3:39Neil deGrasse Tyson?

  All right. If we, the observers of things falling into a black hole, see everything freeze at the event horizon, how does the black hole ever gain mass? As far as our measuring devices would ever.

• 3:53Janna Levin?

  Yeah, it's, it's actually

• 3:58Janna Levin?

  a little bit of a subtle question, but for a while, it's so subtle that for a while, people used to call them frozen stars because they thought that they just sort of froze and never actually became black holes. But the argument is actually that if I'm falling into a black hole, I have a little bit of mass relative to the mass of the black hole. And so I have my own gravitational field. And as I get epsilon, very, very close to the event horizon of the black hole, I actually deform the event horizon so that it bubbles around me. And I actually fall in in a finite time, even to somebody far away.

• 4:37Neil deGrasse Tyson?

  Whoa.

• 4:38Janna Levin?

  So even to somebody far away, they would have to say, so if I threw in something big, like a star or another black hole, you will see the event horizons absolutely bubble deform, enveloping each other in a finite time because of the curved spacetime of the other object, deforming the event horizon, and it will all happen before your eyes.

• 5:01Neil deGrasse Tyson?

  Wow. So what you're saying is you have your own, not your own event horizon, but you have your own deformation in this, in the fabric of spacetime.

• 5:10Janna Levin?

  Yep. And that will deform the event horizon for a second, until it absorbs me. And then, you know, black holes are perfect. They will shed any of those imperfections very, very quickly. But for a second, it will deform, you'll get absorbed, and then it'll usually send out some gravitational waves and ring down.

• 5:26Neil deGrasse Tyson?

  Wow. Okay.

• 5:27Chuck Nice?

  It's like, it's like hitting a tennis ball with an invisible racket.

• 5:34Janna Levin?

  I like it.

• 5:35Neil deGrasse Tyson?

  Yeah.

• 5:37Janna Levin?

  So that's why, like, when we heard the two black holes collide, and it happened, and it was over, and one black hole formed, it didn't take an infinite amount of time. And that's because both black holes were so big that their own gravitational disturbance of spacetime was so strong that it actually happens to us. We really, we really see it.

• 5:58Neil deGrasse Tyson?

  They don't freeze into their own event horizons.

• 6:00Janna Levin?

  Right.

• 6:01Neil deGrasse Tyson?

  That's really weird.

• 6:02Janna Levin?

  Yeah. So, so the objects are both so big, and you can actually see in the simulations of the event horizon that it looks like a big barbell for, you know, it really deforms. Yeah, dumbbell, dumbbell.

• 6:15Neil deGrasse Tyson?

  Somebody's never been to the gym, is that right?

• 6:19Janna Levin?

  I'm not much of a weightlifter, I don't know. Yeah, and so it happens fast, actually, even to us from far away.

• 6:31Neil deGrasse Tyson?

  Well, thank you for clarifying that, because I did not make that part of this evident in my answer. And Chuck, maybe we can put some indicator back to this posting from Patreon Q&A that we did just recently.

• 6:45Chuck Nice?

  Yeah, yeah. Man, that is really cool stuff, though. All right, let's go to Patreon. Speaking of Patreon, we always start with a Patreon patron, because Patreon people support us financially. Thank you, guys. And this is Cody Klubowski, or Klubowski, who says, "If time is relative to a person's experience of it, is there a universal base time? Or is time only relative?"

• 7:21Chuck Nice?

  Is there a Greenwich Mean Time for the universe?

• 7:25Neil deGrasse Tyson?

  Yeah, yeah, we're standard time.

• 7:29Neil deGrasse Tyson?

  What have you done with it?

• 7:31Janna Levin?

  Well, actually, when we say things like the universe is 13.8 billion years old, we are referencing a particular cosmic time that, on average, is about the same for every galaxy. So if you are not moving relative to the expansion of the universe, the time you will measure is this cosmic time we talk about. So it's not 13.8 billion years just for us on Earth, and a completely different age for somebody else in a different galaxy. As long as the galaxy is relatively slow-moving compared to the expansion of the universe, it's just kind of going along with things for the ride, then this is your equivalent kind of mean time.

• 8:16Janna Levin?

  It's a cosmic time that we can all agree on.

• 8:19Neil deGrasse Tyson?

  Wow. What you're saying is because galaxies have motion among other galaxies.

• 8:24Janna Levin?

  Yeah.

• 8:25Neil deGrasse Tyson?

  So, so that has nothing to do with the expanding universe.

• 8:28Janna Levin?

  Yeah.

• 8:28Neil deGrasse Tyson?

  But this motion, you can, if they go really fast or slow, there'd be a

• 8:32Janna Levin?

  Yeah.

• 8:33Neil deGrasse Tyson?

  A time shift, a relative time shift, but that's, that's, that's a detail relative to the

• 8:40Janna Levin?

  It's a tiny, small, small correction, basically. And, and if you were traveling relative to the expansion of the universe, you're the speed of light for the entire history of the universe, you would certainly disagree about the age of the universe. You would not be saying it's, it's roughly 14 billion years.

• 8:58Neil deGrasse Tyson?

  But no galaxy's doing that.

• 9:00Janna Levin?

  No galaxy's doing that. And in fact, even if they were going fast at once, there's a lot of that, that cosmic expansion slows them down. They tend to slow, you know, so all the galaxies tend to kind of get very slow moving relative to the expansion of the universe.

• 9:13Neil deGrasse Tyson?

  So, what about the fact that as I see farther away,

• 9:17Janna Levin?

  Mm-hmm.

• 9:18Neil deGrasse Tyson?

  the speed of the galaxy receding from me is getting greater and greater?

• 9:22Janna Levin?

  Yeah, it's a great question. Yeah.

• 9:24Neil deGrasse Tyson?

  So there's some distance at which it might be receding at the speed of light.

• 9:28Janna Levin?

  Yeah.

• 9:28Neil deGrasse Tyson?

  For me, I should see no time pass for that object. Is that not correct?

• 9:34Janna Levin?

  No. So actually, what's happening is the object itself is not moving in, in some sense, relative to the expansion of the universe at all. It's the space that's stretching between us. And so the space is stretching between us faster than the speed of light. But in most circumstances, a light beam can just still make its way over to us eventually, if you wait long enough. And so if the universe is slowing down, every galaxy will eventually be visible to us as we wait long enough.

• 10:09Neil deGrasse Tyson?

  Right.

• 10:09Janna Levin?

  But if the universe is actually accelerating, which is what it seems to be doing right now, there will be a distance beyond which the light will not be able to outrate the expansion of the universe. And we will never see those galaxies. And it will be like having an event horizon like you do for a black hole. It will be a cosmic event horizon where we are never to see or know or be able to communicate with what goes on beyond that distance.

• 10:34Neil deGrasse Tyson?

  Because it is receding faster than the light can overcome the stretching of the space.

• 10:38Janna Levin?

  That's right. So the light is racing and racing and racing, but the space is stretching faster and it's never going to overcome.

• 10:43Neil deGrasse Tyson?

  OK, so the one where it is just exactly at the expansion rate for the light to exactly compensate for the stretching of the universe, if we see that light, that's going to be frozen, isn't it?

• 10:58Janna Levin?

  Oh, so, yes, in the same way that there's... So if it's accelerating and there's some... And that happens and there is something, it's an event horizon. Indeed, there is a last signal we will get. So if something is just on this side of that event horizon, we'll see it in the infinite future. And if something's just on the other side, the light will just seem to hover there, will never seem to get to us.

• 11:22Neil deGrasse Tyson?

  OK, but will we see it reckon time differently from how we reckon time?

• 11:29Janna Levin?

  Ah, well, it depends on what you mean by "it" there. The galaxy itself could be measuring the same cosmic time.

• 11:35Neil deGrasse Tyson?

  That's what I was wondering.

• 11:36Janna Levin?

  But light, you know, almost registers no passage of time.

• 11:40Neil deGrasse Tyson?

  Yeah, no passage of time, right.

• 11:41Janna Levin?

  Yeah. But the galaxy itself, as long as it was just being dragged along with the expansion, should agree with us that the universe is about 14 billion years old.

• 11:49Neil deGrasse Tyson?

  That's the answer.

• 11:49Janna Levin?

  Yeah.

• 11:50Chuck Nice?

  So there you go. That's it. There it is. Good light don't crack. That's all there is.

• 11:59Janna Levin?

  You're such a nut, Chuck.

• 12:03Janna Levin?

  Oh, did you notice I'm wearing my... I meant to show you this earlier. It's my space shuttle, BOLO.

• 12:10Neil deGrasse Tyson?

  Oh, very nice.

• 12:11Janna Levin?

  Yeah.

• 12:11Chuck Nice?

  Nice.

• 12:12Janna Levin?

  I always have to wear something themed for you, Neil.

• 12:15Neil deGrasse Tyson?

  Thank you. Thank you. I feel bad because I got... I don't... I feel bad.

• 12:19Janna Levin?

  It's quarantine. There's only so much we can do.

• 12:24Neil deGrasse Tyson?

  I've got another question.

• 12:25Chuck Nice?

  All right, let's go back to Patreon and um, let's go to Peter Jacobs. Peter Jacobs says.

• 12:31Neil deGrasse Tyson?

  You didn't pick him just because you can pronounce his name.

• 12:33Chuck Nice?

  Yes, I did.

• 12:37Chuck Nice?

  You know, because the other person's name was Flavi Flop. All right, Peter Jacobs wants to know this.

• 12:45Chuck Nice?

  Peter Jacobs says, is energy a thing? Or is it just a relationship between things? And he's coming to us from Queensland, Australia. Good day, mate. Good day, mate.

• 12:58Neil deGrasse Tyson?

  Good day, and actually, we have to take a break right now. And we'll come back to that because that's an excellent question. It's, I think it has a deeper, broader significance. Does the measurement of anything? Does it only have meaning with regard to something else? Can it, can it have absolute meaning without regard to whoever is looking at it or measuring it? So when we come back, we will pick up Cosmic Queries Theoretical Physics Edition with our friend and my colleague, Janna Levin.

• 13:52Neil deGrasse Tyson?

  We're back, Cosmic Queries Theoretical Physics Division.

• 14:00Neil deGrasse Tyson?

  I need help, and we got help, and we didn't have to reach too far. Janna Levin, Jenna, always good to have you.

• 14:07Janna Levin?

  Always good to be here.

• 14:09Neil deGrasse Tyson?

  All right, you got the question. Here, yeah, here.

• 14:13Chuck Nice?

  Exactly. We're all here and, yeah. So Peter Jacobs, before the break, asked if energy a thing? Is energy a thing? Or is it just a relationship between things?

• 14:29Neil deGrasse Tyson?

  Ooh, I love that. Jenna, where does that come from? Where's that going?

• 14:33Janna Levin?

  I don't know. I thought, I thought you were gonna have a prompt, but I'll do a quick one and then I'd love to hear your opinion.

• 14:40Neil deGrasse Tyson?

  Okay, okay.

• 14:41Janna Levin?

  To some, you know, I think it's both. So for instance, if I'm sitting still in space, but I'm moving in time, I still have some energy. That's what Einstein taught us. I have a kinetic energy in time, in some sense, because of my motion in time. And that's my E equals mc squared energy. And that's my basic, you can actually unambiguously break my atoms apart and get that energy out and blow things up and have real impact.

• 15:15Neil deGrasse Tyson?

  Without reference to anything else?

• 15:16Janna Levin?

  Without reference to anything else. But if you're, we're astronauts floating in space and I think I'm just moving in time with my kinetic energy equals mc squared in time, but you go whizzing past me, you think I'm moving past you. And so now you think I have a relative kinetic energy that I don't think I have. That's my motion in space. So it's kind of both.

• 15:41Neil deGrasse Tyson?

  Wow.

• 15:42Janna Levin?

  Kind of both.

• 15:44Neil deGrasse Tyson?

  Okay, so in other words, okay, the way it wouldn't be both is if the question were asked whether mass energy was something relative to something else. Because I can measure you to have a different amount of kinetic energy in time versus

• 16:00Janna Levin?

  Right. I can say I have no kinetic energy in space and you can say I have a lot of kinetic energy in space because you just saw me fly by.

• 16:07Neil deGrasse Tyson?

  And we both, because I was flying by you, but how would I know? Right. So, so, but if I add up your time kinetic, your time energy and your spatial energy, that should be a constant no matter what.

• 16:20Janna Levin?

  Um, so that's an interesting question. What's actually constant is a combination of my energy and my spatial momentum, my kinetic energy. Yes, that com- a combination of the squares, weirdly, of my energy and my, in time, and my kinetic energy. That, that will be the same, even though we'll disagree about what's what.

• 16:46Neil deGrasse Tyson?

  We have a way to calculate what would be the same for every observer onto you.

• 16:50Janna Levin?

  That's right. And so it's interesting. So like, let's say you tell me that, uh, you're looking three feet to your left. I might disagree that it's to your left. I might say it's to my left, or I'm sorry, my right. But we're gonna, we're gonna agree on the, the overall combination. And so it's similar with like, uh, time, energy and physical, spatial, kinetic energy. We're gonna disagree on which piece, if it's, how it's distributed, but we're gonna agree on a combination.

• 17:21Neil deGrasse Tyson?

  Excellent.

• 17:23Chuck Nice?

  That is really good.

• 17:24Neil deGrasse Tyson?

  By the way, I forgot all about that formula. We have the squares of the energies. I remember that now. I just like.

• 17:29Janna Levin?

  Yeah, E squared minus P squared.

• 17:31Neil deGrasse Tyson?

  Yeah, exactly. From my relative.

• 17:32Janna Levin?

  Minus P squared.

• 17:33Neil deGrasse Tyson?

  Yeah.

• 17:34Chuck Nice?

  Alright, so.

• 17:38Neil deGrasse Tyson?

  I felt left out a little bit on that.

• 17:40Chuck Nice?

  I'm like, hmm.

• 17:44Janna Levin?

  I feel like we could keep going, but we'd regret the rabbit hole we'd fall down.

• 17:47Chuck Nice?

  And that is a rabbit hole, man, for real. But that's, that's a very cool question. Thank you, Peter. Uh, let's go to Facebook and Steve Cotton. Uh, Steve says, well, quantum entanglement allow for FTL or instant communication to exist between worlds with light years of distance between them. This is clearly a Star Talk fan, I mean, a Star Trek fan who, who knows about subspace, which is how they get around talking to people in almost real time, even though they're in different galaxies. They have this thing called subspace. And what's it mean? Nothing. It means.

• 18:26Neil deGrasse Tyson?

  Wait, wait, Chuck, just to be clear, you're laughing at it, but at least they thought about that problem and came up with a sci-fi solution.

• 18:33Chuck Nice?

  Okay, alright, okay, I'm gonna give you that. That's.

• 18:36Neil deGrasse Tyson?

  Don't make me come here and slap you.

• 18:38Chuck Nice?

  You know what? I, I gotta give it to you. That is actually, that is a seriously, um, salient consideration. I gotta give it to you. You're right. Yeah.

• 18:50Chuck Nice?

  So anyway, so anyway, go ahead.

• 18:53Neil deGrasse Tyson?

  So Jana, let me, let me, let me.

• 18:54Janna Levin?

  I, I missed a question.

• 18:55Chuck Nice?

  Well, quantum entanglement allow for FTL or instant communication to exist between worlds with light years or distances between them.

• 19:05Neil deGrasse Tyson?

  Say, Diana, let me just ask you something. I want to prep this and ask you, do you even need quantum entanglement if you have wormholes?

• 19:14Janna Levin?

  Uh, no, you don't need quantum entanglement if you have wormholes.

• 19:18Neil deGrasse Tyson?

  And wormhole, you can actually put material things through the wormhole and and I just open a portal and it's right there and it's a back door.

• 19:26Janna Levin?

  Yeah, and Neil, as I know you've made the point before, it's not that it's faster than light travel. You've just found a shortcut. It's like somebody going uh, between New York and New Jersey by going all the way around the globe, right? And thinking it's really far away and you tell them, actually, you can just go this way. The shorter way. So the wormhole gives you a shorter way.

• 19:47Neil deGrasse Tyson?

  The wormhole is the Lincoln Tunnel, okay?

• 19:50Janna Levin?

  Yeah. So, um, so the wormhole makes a veritable shortcut where you travel slower than the speed of light and you just have a shorter distance to go.

• 19:58Neil deGrasse Tyson?

  Right. And, and you're slower than the speed of light while you're in the wormhole?

• 20:02Janna Levin?

  Totally, yeah.

• 20:04Neil deGrasse Tyson?

  Right.

• 20:04Janna Levin?

  And there, you know, the other thing that I know we've talked about before is this warp drive idea, which is that it's, space can expand faster than the speed of light and contract faster than the speed of light without violating special relativity or any of those laws. So you can also bring something closer, take a short step across the pond and then push it further away again by just expanding the space.

• 20:26Neil deGrasse Tyson?

  This would be awesome control over the space-time continuum to accomplish this.

• 20:31Janna Levin?

  Awesome control.

• 20:32Neil deGrasse Tyson?

  Okay, so, so what would, what's more likely to happen? That we perfect quantum entanglement faster than light communication? Or that we open up wormholes throughout the galaxy?

• 20:45Janna Levin?

  Quantum entanglement is actually happening. Like, we do it in the lab. I mean, we don't do it in the scale that, uh, the question was asked from one galaxy to another, because we also can't get our own selves. To another galaxy, but we can definitely do this experiment where we throw things faster than that we throw information faster than the speed of light.

• 21:06Chuck Nice?

  That's amazing. I mean, but I mean.

• 21:09Janna Levin?

  It is amazing. I mean, I even think it's amazing. Like, I know the theory, and then you find out somebody's done it in the lab, and you're like, what?

• 21:17Chuck Nice?

  I mean, because the implications there are kind of like, if you look at all of our telecommunications today, it started with one quick, one sentence, you know, Watson, come here. So.

• 21:32Janna Levin?

  Yeah.

• 21:33Chuck Nice?

  And the dude was literally in the next room. And they thought that was like, oh, my God, that's amazing. Oh, he just called me in the, I mean, you, he could have actually went like this, Watson, it wasn't. Okay, and it would have been more effective.

• 21:50Janna Levin?

  I know.

• 21:51Chuck Nice?

  Honestly, that's what you're saying is just mind blowing.

• 21:56Janna Levin?

  But Chuck, don't you think we're, we're so unappreciative of how amazing this is right now? Like, I don't even know where to look. I got so many squares to look at on my screen. I, I don't even know. Like, I'm looking all over the place, but we're taking so for granted that this, we're doing this is amazing. This is phenomenal. We're just used to it.

• 22:13Chuck Nice?

  Wow.

• 22:14Janna Levin?

  Yeah.

• 22:14Neil deGrasse Tyson?

  So now, a quick question, is what's the difference, functional difference between a, a, a collapsed wave function in the quantum entanglement, and that information is shared instantly, not just faster than the speed of light, instantly.

• 22:31Janna Levin?

  Yeah.

• 22:32Neil deGrasse Tyson?

  What's in between that?

• 22:33Janna Levin?

  Oh, but see, here's, oh, sorry, I don't mean to interrupt you, but instantly according to whom? So, so there is some very tricky things about because, because in simultaneity is relative.

• 22:48Chuck Nice?

  All right, okay, that's it. Show's over, show's over. I gotta go. I'm sorry.

• 22:56Janna Levin?

  I can't, dropping my headphones doesn't seem like quite as dramatic.

• 23:01Chuck Nice?

  Wow.

• 23:01Neil deGrasse Tyson?

  And I am not dropping this microphone.

• 23:03Janna Levin?

  Yeah.

• 23:04Chuck Nice?

  Drop them.

• 23:05Janna Levin?

  Okay, okay, sorry, Neil. Okay, go ahead. What you were saying, yes, so it's instantaneous according to the person who does the observation.

• 23:12Neil deGrasse Tyson?

  Tunneling, you, a particle is over here, and there's a barrier of any kind, and there's a chance it'll just show up on the other side of that barrier.

• 23:21Janna Levin?

  Yeah.

• 23:22Neil deGrasse Tyson?

  But when it does so, that happens instantly.

• 23:26Janna Levin?

  Yeah.

• 23:29Janna Levin?

  That's, it does so instantly, but you can kind of calculate the natural time scale for it to happen.

• 23:38Neil deGrasse Tyson?

  Gotcha, okay.

• 23:38Janna Levin?

  It doesn't, but it doesn't mean it doesn't happen instantly. But it does mean like, oh, do I have to wait for a googolplex of years for this to happen? Or is it likely to happen in a year or in a second?

• 23:52Neil deGrasse Tyson?

  Gotcha.

• 23:53Janna Levin?

  And you can do experiments where it's more likely to happen in a short period of time. So if you do a whole bunch of them, if you put a whole bunch of particles in a box in your laboratory, you'll see a whole bunch

• 24:02Neil deGrasse Tyson?

  Right.

• 24:03Janna Levin?

  tunnel through on the other side at about a second.

• 24:05Neil deGrasse Tyson?

  Mm-hmm.

• 24:06Janna Levin?

  And so, so, so you're right, it's still instantaneous, but it's just what's the likelihood of it happening in a certain period of time?

• 24:12Neil deGrasse Tyson?

  Now, I gotta throw this in here, just, I'm being Professor Neil in this moment. But we knew for the longest time that if they were ever gonna undergo nuclear fusion anywhere in the universe, that the centers of stars would be the place that that would have to happen.

• 24:29Janna Levin?

  Yeah.

• 24:30Neil deGrasse Tyson?

  So what people did was calculate the temperature in the centers of stars. And we're getting millions of degrees. Okay? Just through the thermodynamics of that.

• 24:39Janna Levin?

  Yeah.

• 24:40Neil deGrasse Tyson?

  You run the quantum calculation, sorry, you run the calculation of is that a high enough temperature for proton to overcome their natural repulsion? You have two positive charges, they don't wanna get close to each other.

• 24:55Janna Levin?

  Yeah.

• 24:55Neil deGrasse Tyson?

  Use them, you gotta bring them together to turn them into another element. So can you overcome it? They did the math and they could not overcome the repulsion. So they said the centers of stars can't be the place where this happens. Because we did the math and we know thermodynamics. And then quantum physics gets discovered and then we learn about tunneling. And then we learned that at the temperatures in the centers of the stars, the proton can disappear from here and show up right next to the other proton bypassing the electrical barrier. And when it bypasses the barrier, it fuses, you turn hydrogen into helium. And it was the tunneling that even enabled anybody to accept

• 25:38Neil deGrasse Tyson?

  that stars could be the source of everything.

• 25:41Chuck Nice?

  What?

• 25:41Neil deGrasse Tyson?

  I just had to throw it.

• 25:42Chuck Nice?

  That is amazing!

• 25:44Neil deGrasse Tyson?

  Yes. The temperature's not high enough.

• 25:47Chuck Nice?

  Why have you never told me this story before? Well, it's not really a story, but still.

• 25:52Janna Levin?

  It's sort of a story.

• 25:53Neil deGrasse Tyson?

  It was on a need to know basis.

• 25:56Chuck Nice?

  By the way, that is just, so the, the original calculations led them to believe that this is not the place that it could actually happen.

• 26:06Neil deGrasse Tyson?

  It, but, but in all fairness, Arthur Eddington, I think it was him, was one of the great towering theoretical physicists at the turn of the century, 100 years ago. Someone came up to him and said, "Do you see, it's impossible, you can't overcome this electrical repulsion." And he said, "I don't care if there's any place in the universe where this is gonna happen at all, it's gonna be in the center of the star, we're gonna find out one day."

• 26:34Janna Levin?

  Yeah, I mean, you can kind of, you know, when you get in a zone and your numbers are off by not enough for you to abandon

• 26:44Neil deGrasse Tyson?

  Right.

• 26:44Janna Levin?

  the idea.

• 26:45Neil deGrasse Tyson?

  Right, right.

• 26:46Janna Levin?

  They're off by enough for you to know you haven't understood everything, but not enough for you to abandon the idea.

• 26:52Neil deGrasse Tyson?

  Right, so you stick with it.

• 26:53Chuck Nice?

  Wow, that is super.

• 26:56Neil deGrasse Tyson?

  Chuck, it was a need to know basis, I'm sorry.

• 26:58Chuck Nice?

  Yeah, that is super fascinating, though, that, I mean, that's, god, that's so cool. All right, here we go. Fred Pibonessa, whatever. Fred.

• 27:11Neil deGrasse Tyson?

  Ever applied to work at the United Nations, okay?

• 27:13Chuck Nice?

  I know, I will, I will start many global incidents.

• 27:18Chuck Nice?

  Like, "What you calling me?" Anyway.

• 27:23Neil deGrasse Tyson?

  Chuck was giving the translation, you gotta let him, you cut him through slack.

• 27:26Chuck Nice?

  Uh, it says, um, "What is space made of?" Wow, cuz, you know, we hear about the fabric of space, what is that fabric?

• 27:35Neil deGrasse Tyson?

  Ooh, okay Chuck, we don't have time to answer that until the next break.

• 27:39Chuck Nice?

  Okay.

• 27:39Neil deGrasse Tyson?

  How do you like that? So, love that question, and I know Jana loves it too, look at that smile on her. There's a lot that's gonna come out of this one.

• 27:47Janna Levin?

  Totally.

• 27:47Neil deGrasse Tyson?

  Uh, we're gonna take a quick break from StarTalk Cosmic Queries: Theoretical Physics in Discovery. Go to the right.

• 28:08Chuck Nice?

  Hey, we'd like to give a Patreon shout out to the following Patreon patrons, Marcus Guerra and Mahmoud Hyatt. Guys, thanks so much for the gravity assist. Without you, we could not do this. And for anyone else who would like their very own Patreon shout out, please go to patreon.com/stargtloradio and support us.

• 28:40Neil deGrasse Tyson?

  We're back for the third and final segment of StarTalk Cosmic Queries Theoretical Physics Edition. I love it. We should do this more often, Chuck. Man, it's really good. Really good. Of course, I need help for that. Jana Levin, Jana. So Chuck, we left off.

• 28:57Chuck Nice?

  All right. So Fred P. Vanessa, right? Nope. Yep.

• 29:06Chuck Nice?

  Nope.

• 29:08Neil deGrasse Tyson?

  P. Vanessa.

• 29:10Chuck Nice?

  Pio Vez... Pio Vazana. That's what it is.

• 29:14Neil deGrasse Tyson?

  Okay.

• 29:15Chuck Nice?

  Pio Vazana. Okay. Sorry, Fred.

• 29:19Neil deGrasse Tyson?

  Pio Vazana, but his first name is Fred.

• 29:22Chuck Nice?

  It's probably Federico or Frederico, and they just went with Fred.

• 29:27Janna Levin?

  He's making it easier for Chuck.

• 29:30Chuck Nice?

  Anyway, Fred wants to know this. What is space made of? So everybody talks about the fabric of space. What's that fabric? Is it?

• 29:38Neil deGrasse Tyson?

  Let me lead into you here, Jana. So we like to think of, just naively, that, okay, there's Earth, and then there's air, and then where there's no air, there's empty space. So we have a word for what we think contains nothing. So can't, holding aside stray atmospheric particles that might be floating up there, that's not what we were talking about here.

• 30:04Janna Levin?

  No.

• 30:05Neil deGrasse Tyson?

  Even if we were, let's talk about what's between the particles. So give me the most empty space you can.

• 30:11Janna Levin?

  Yeah.

• 30:12Neil deGrasse Tyson?

  Talk about it.

• 30:14Janna Levin?

  Wow. Well, I'm going to give an answer that I don't 100% understand or believe. Okay? But...

• 30:24Neil deGrasse Tyson?

  No, wait, Jana, I get that from Chuck all the time.

• 30:28Janna Levin?

  So, right now...

• 30:31Neil deGrasse Tyson?

  He neither understands nor believes.

• 30:33Janna Levin?

  Yeah.

• 30:34Neil deGrasse Tyson?

  Chuck's mouth all the time. That's it. That's where I'm a Viking.

• 30:37Janna Levin?

  I think that this is, I would say this, I think this is how we can understand it now.

• 30:43Neil deGrasse Tyson?

  Okay.

• 30:43Janna Levin?

  And that our understanding will change.

• 30:45Neil deGrasse Tyson?

  Good.

• 30:46Janna Levin?

  With time. So, so right now, I know that my room is full of electric and magnetic fields. And I cannot see them, but they make a fabric of the electromagnetic fields in the universe. They're just there. I know they're there because I'm looking at you right now on an electronic instrument, and this is just a reality that the fields are here. Even though I can't, my eyes aren't good detectors of them, my fingers aren't good detectors of them, and I don't notice them.

• 31:15Neil deGrasse Tyson?

  But just to be clear, the fact that light can move through empty space, from wherever it started to its destination, your retina.

• 31:23Janna Levin?

  Yeah.

• 31:24Neil deGrasse Tyson?

  Being space is permeated by electromagnetic energy.

• 31:28Janna Levin?

  Yeah. And we can see those, we can see that version of electromagnetic energy, the one that oscillates at just the right frequency that my eyes evolved to be able to detect. But I can't see the ones that my phone's detecting. Like, when my phone goes off, I don't see, like, flashes.

• 31:43Neil deGrasse Tyson?

  Versus microwave light?

• 31:45Janna Levin?

  Yeah, or even not light at all, like steady electric fields. But yes, most of them are usually light signals. But right now, there's probably just a steady electric field in this room that permeates a whole space. It's just from god knows what, and I can't see it, feel it, touch it, because I'm, my, you know, it doesn't resonate with my particles very well. So I can say that there are fields that permeate the universe, and they make a fabric of that field, of the electromagnetic field. I would say, in analogy, there is a gravitational field. And the gravitational field is analogous to a curved spacetime. It describes the curved spacetime. The gravitational field defines

• 32:27Janna Levin?

  the shape of spacetime. And my eyes are not good detectors of it, and my hands don't touch it. But I fall along it. If I were to jump off my chair, I would fall along this gravitational field. And so that is the fabric of space, in some sense.

• 32:47Neil deGrasse Tyson?

  All right, but, Jana, I think that's a cop-out answer, because...

• 32:50Janna Levin?

  Fifty cuffs. Oh, sure, you're far away. Say that to me in person.

• 32:58Neil deGrasse Tyson?

  No, I know, I totally followed the answer, but let me take you a step, I want to push you.

• 33:04Janna Levin?

  Yep.

• 33:05Neil deGrasse Tyson?

  You are describing what happens to be in the empty space of the universe in which we live. Can you imagine empty space through which there is no electromagnetic field? And where there is no curvature from matter?

• 33:27Janna Levin?

  Yeah, I cannot imagine space as separated from a gravitational field, including a flat, empty gravitational field.

• 33:38Neil deGrasse Tyson?

  But when we learn general relativity, one of the ways you start there is imagine a flat space with no matter.

• 33:47Janna Levin?

  Yep, I would still call that a gravitational field. I would just call it a flat, straight, very boring gravitational field.

• 33:57Neil deGrasse Tyson?

  A gravitational field with no sources of gravity in it.

• 34:00Janna Levin?

  Yeah.

• 34:04Neil deGrasse Tyson?

  I feel like you.

• 34:06Janna Levin?

  So let me put it this way, it doesn't mean it doesn't have space in it. So let me put it this way.

• 34:12Neil deGrasse Tyson?

  You're trying to give the existence of space, you're trying to credit the existence of space.

• 34:17Janna Levin?

  I would say that's...

• 34:17Neil deGrasse Tyson?

  Something that happens to be in it.

• 34:20Janna Levin?

  No, no, I would say it this way, I would say there are gravitational fields even with zero sources. So I would put it that way. So I would say, I take Einstein's equations, which as you said, says, put in a source, a sun, a black hole, a moon, whatever, and you will find the curvature in the shape of spacetime, also known as a gravitational field. I can take Einstein's equations and put in zero sources and find as a solution a gravitational field that is just extremely plane, where things travel on straight lines.

• 34:54Neil deGrasse Tyson?

  Okay.

• 34:55Janna Levin?

  So in other words, it's the ground state or the lowest energy state of the field. And that there is no state of the field where space doesn't exist. It just is the ground state, it is the ground state.

• 35:11Neil deGrasse Tyson?

  I know. Wait, so what about a universe that pops out in the multiverse that has no matter and no energy in it?

• 35:21Janna Levin?

  Well, are you asking what it would be?

• 35:23Neil deGrasse Tyson?

  Yeah.

• 35:24Janna Levin?

  Well, this is, you know,

• 35:29Janna Levin?

  it would be, in principle, if there are no observers, it becomes one of those questions of there's no one to measure time, there's no passage of time, there's no experience of space. It's gotta have something in it to even ask the questions.

• 35:47Neil deGrasse Tyson?

  All right, okay, so, all right.

• 35:49Janna Levin?

  But, but, but a universe that pops out of existence with nothing in it could just be a plain old flat space with nothing in it. I mean, I don't know, but you're really, you're talking about something where there's no meaning to the passage of time.

• 36:02Neil deGrasse Tyson?

  So how about, now, let's get quantum on this.

• 36:05Janna Levin?

  Yeah.

• 36:05Neil deGrasse Tyson?

  Uh, I've read about, and I just, as you said earlier, I accept it because people I trust have thought about this and are far better experts in quantum physics than I am. They describe space as a seething soup, virtual particles popping in and out of existence.

• 36:23Janna Levin?

  Yep.

• 36:24Neil deGrasse Tyson?

  Virtual matter, antimatter particle pairs.

• 36:27Janna Levin?

  Yeah.

• 36:27Neil deGrasse Tyson?

  But what is a virtual particle?

• 36:29Janna Levin?

  So, um, this goes back to the Heisenberg uncertainty principle, which is really initiates the whole quantum revolution. And the uncertainty principle...

• 36:39Neil deGrasse Tyson?

  Heisenberg, not from Breaking Bad, just to be clear.

• 36:42Janna Levin?

  Oh, no, but, but, do you think they were fans of physics? I don't know. But Heisenberg, German physicist, who realized that there is a level of uncertainty to how much we can know, but the real impact of what Heisenberg said is he said, in some sense, "I can never know a particle is precisely there, so I can never know a particle's not there." So if I have empty space, the uncertainty principle ensures that I cannot declare it to have nothing in it because I can never say with certainty a particle isn't there. In the same way that I can't say for certainty a particle is there.

• 37:22Janna Levin?

  And so, virtual particles are in some sense, a manifestation of this fundamental uncertainty. You cannot have an absolute vacuum-empty state. It cannot be. Uncertainty doesn't allow it. It says that there is always some possibility.

• 37:38Neil deGrasse Tyson?

  How do you measure it?

• 37:40Janna Levin?

  Oh, you know what? We've never measured a vacuum fluctuation. And this is a really interesting, really interesting point, which is something I didn't appreciate until fairly recently, but we do see effects, like there's something called the Casimir effect.

• 37:56Neil deGrasse Tyson?

  Oh.

• 37:57Janna Levin?

  So the Casimir effect, where we put two metal plates together, and it's a way of limiting the number of vacuum states that can exist because of these boundaries. It's sort of like excluding all pot, not every possibility is allowed. And it creates a difference in the vacuum fluctuations on one side of the plates than on the other side of plates. And that creates a pressure differential. And you can actually measure it.

• 38:23Neil deGrasse Tyson?

  So I'd forgotten about that Casimir effect.

• 38:26Janna Levin?

  Yeah.

• 38:26Neil deGrasse Tyson?

  So as I understand it, you have to, you need very flat plates, very parallel, and they have to be separated from each other on the level of the wavelength of the, of the virtual particles themselves.

• 38:40Janna Levin?

  Right. It's a very subtle, small, small detail, very fascinating experiment.

• 38:46Neil deGrasse Tyson?

  And when you do that, they want to actually pull together with a force, a new force that just shows up because of this.

• 38:51Janna Levin?

  And it's like saying the quantum pressure of the fluctuations on one side exceeds the quantum pressure of the fluctuations the other side, because you've made it impossible for some states to exist between these boundaries, basically. And, but, but it's not exactly a direct measurement. You don't measure a virtual particle. And so in some subtle sense, it's a, it's a beautiful indirect measurement. But we, we can't be like, oh, I just saw a particle pop into existence and disappear again.

• 39:22Chuck Nice?

  So basically, what you're saying for Fred is that there can never be nothing.

• 39:27Janna Levin?

  There can never be nothing.

• 39:29Chuck Nice?

  There can never be nothing.

• 39:30Janna Levin?

  There can never be nothing.

• 39:31Chuck Nice?

  That's basically what it comes down to.

• 39:33Janna Levin?

  Yeah.

• 39:33Chuck Nice?

  Just, yeah. Damn.

• 39:35Neil deGrasse Tyson?

  So not even nothing has nothing?

• 39:38Chuck Nice?

  Nothing, right. Nothing is...

• 39:39Neil deGrasse Tyson?

  Nothing has nothing.

• 39:40Chuck Nice?

  Nothing is something.

• 39:42Janna Levin?

  Which is one of the arguments...

• 39:43Chuck Nice?

  Which, by the way, I keep trying to tell my wife that. Like...

• 39:50Janna Levin?

  Um, it's one of the arguments for dark energy is that what dark energy is, and it's connected to the two questions, that what dark energy is...

• 40:00Neil deGrasse Tyson?

  With that mysterious pressure in the vacuum of space.

• 40:02Janna Levin?

  It's the mysterious pressure in the vacuum of space from quantum behaviors, and it's because even in an empty, flat space, the universe that you asked about, Neil, there is a gravitational field, and the gravitational field has an energy associated with it, and it's the energy associated with the quantum fluctuations.

• 40:22Chuck Nice?

  Wow. Okay. God. Damn.

• 40:26Janna Levin?

  Woo, I'm exhausted.

• 40:27Neil deGrasse Tyson?

  We gotta do more theoretical physics.

• 40:30Janna Levin?

  I love this. I love theoretical physics.

• 40:33Chuck Nice?

  It's amazing. This is crazy stuff.

• 40:36Neil deGrasse Tyson?

  Yeah.

• 40:36Chuck Nice?

  This is cra... I gotta tell you the truth. I am so sorry that I spent so much of my young life, uh, doing drugs. I could've been do... I could've been doing this! This is just as good! I could've been easily... I was hanging out with the ru... Here I am, hanging out with the stupid people who wanna smoke weed and drink. I should've been hanging out with the doggone physicists!

• 41:02Janna Levin?

  I know, man. I'm telling you.

• 41:05Chuck Nice?

  Damn!

• 41:06Neil deGrasse Tyson?

  That's how we roll.

• 41:09Neil deGrasse Tyson?

  Yeah, always great to have you on.

• 41:11Janna Levin?

  Always fun to be on, guys.

• 41:13Neil deGrasse Tyson?

  We need more installments of theoretical physics.

• 41:15Janna Levin?

  Yeah, happy to. Anytime, and everyone hang in there. It's good to see you all.

• 41:20Neil deGrasse Tyson?

  Thank you. In the Corona-verse, Chuck.

• 41:21Janna Levin?

  In the Corona-verse.

• 41:22Neil deGrasse Tyson?

  Stay safe.

• 41:23Chuck Nice?

  A pleasure. Stay safe, guys.

• 41:25Neil deGrasse Tyson?

  All right, good.

• 41:25Janna Levin?

  Stay safe, guys.

• 41:26Neil deGrasse Tyson?

  Neil deGrasse Tyson, your personal astrophysicist, signing off from Cosmic Queries Theoretical Physics Edition. As always, keep looking out.