Cosmic Queries: A Taste of Space, with Matt O’Dowd

Neil deGrasse Tyson and comic co-host Eugene Mirman answer fan submitted Cosmic Queries with Matt O’Dowd, astrophysicist and host of PBS Space Time, about vacuum decay, mapping the galaxy, diamond planets, a simulation universe and much, much, more! NOTE: StarTalk All-Access subscribers can watch or listen to this entire episode commercial-free. Find out more at https://www.startalkradio.net/startalk-all-access/

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.

• 0:21Neil deGrasse Tyson?

  This is StarTalk. I'm your host Neil deGrasse Tyson, your personal astrophysicist. And for today's edition, it's Cosmic Queries Potpourri. And I've got Eugene Mirman, visiting in from Boston. Used to be local and now you're not anymore.

• 0:37Eugene Mirman?

  I know.

• 0:38Neil deGrasse Tyson?

  Why?

• 0:39Eugene Mirman?

  Uh, you know.

• 0:40Neil deGrasse Tyson?

  You got married, got kids and stuff?

• 0:41Eugene Mirman?

  Got married, children, moved to Massachusetts.

• 0:43Neil deGrasse Tyson?

  Damn, that happens.

• 0:44Eugene Mirman?

  Yeah.

• 0:44Neil deGrasse Tyson?

  That happens. Well, welcome back.

• 0:46Eugene Mirman?

  Thank you.

• 0:46Neil deGrasse Tyson?

  We're here in the YouTube studios. Uh, I don't know why, but that's where we are. Lindsay, why are we in the YouTube studio?

• 0:53Eugene Mirman?

  We're collaborating.

• 0:54Neil deGrasse Tyson?

  We're collaborating with YouTube. Well, how do we know that? Because Matt O'Dowd is here. Uh, in from Australia. That's your home motherland.

• 1:02Matt O'Dowd?

  Well, Australia, once upon a time.

• 1:04Neil deGrasse Tyson?

  Once upon a time. And we've got you now. You're a professor of physics and astronomy.

• 1:09Matt O'Dowd?

  Happy to be got.

• 1:10Neil deGrasse Tyson?

  At, uh, at the City University of New York.

• 1:13Matt O'Dowd?

  That's right.

• 1:13Neil deGrasse Tyson?

  Lehman College up in the Bronx where I'm from.

• 1:15Matt O'Dowd?

  Hey.

• 1:15Neil deGrasse Tyson?

  And, uh, you're here because you have a YouTube channel.

• 1:20Matt O'Dowd?

  I do, yeah.

• 1:21Neil deGrasse Tyson?

  And it's part of the PBS universe. I'm very delighted to learn that PBS has, uh, a digital studio.

• 1:27Matt O'Dowd?

  Exactly.

• 1:28Neil deGrasse Tyson?

  And you, your program within that is called?

• 1:31Eugene Mirman?

  Spacetime?

• 1:32Matt O'Dowd?

  Thank you Eugene, fan. Uh, yeah, so Spacetime, it's a PBS digital studio show.

• 1:38Neil deGrasse Tyson?

  And these are shorts, like four or five minutes each, or what?

• 1:40Matt O'Dowd?

  We go a little over. We tend to go eight to 10.

• 1:44Neil deGrasse Tyson?

  Ooh.

• 1:44Eugene Mirman?

  Can people film for that?

• 1:46Neil deGrasse Tyson?

  Yeah, I know.

• 1:48Matt O'Dowd?

  I, I feel like that people take naps part, part way through, but they wake up for the end where the jokes are.

• 1:55Neil deGrasse Tyson?

  No, that's great. So that's why we've got you here. That's why we're in the YouTube studios. And you're here to help me handle these Cosmic Queries solicited from the internet.

• 2:03Matt O'Dowd?

  I got your back.

• 2:04Neil deGrasse Tyson?

  From our, from our, basically our, our social media base that gets solicited. And sometimes we solicit by topic and then some don't fit in exactly right. And so we put them all in the grab bag. And so Eugene.

• 2:16Eugene Mirman?

  Let's do it.

• 2:17Neil deGrasse Tyson?

  We haven't seen these? And so?

• 2:18Eugene Mirman?

  No.

• 2:19Matt O'Dowd?

  No idea.

• 2:19Neil deGrasse Tyson?

  The two of us will, will work. We'll work at this, alright?

• 2:22Matt O'Dowd?

  Okay, this is where we prove that we have anything up here at all.

• 2:27Eugene Mirman?

  So let's do this. Jordan Thomas, Jordan Thompson from Indianapolis asks Neil, "There once were reptilian the size of buildings, planets made of diamonds, stars five billion times that of our sun, and holes that lead to nowhere. Do you think the universe has any limitations within creation?"

• 2:54Matt O'Dowd?

  So many things to pick on.

• 2:56Neil deGrasse Tyson?

  Well, first, let me just start off by saying, I'm from New York City.

• 2:59Eugene Mirman?

  Yeah.

• 2:59Neil deGrasse Tyson?

  There are no reptiles the size of buildings. Okay, I don't know where he's from.

• 3:02Eugene Mirman?

  Yeah, this feels like, this feels like Iron Maiden lyrics.

• 3:06Matt O'Dowd?

  I want to live in this universe, actually.

• 3:08Eugene Mirman?

  Yeah, were there ever planets made of diamonds?

• 3:10Neil deGrasse Tyson?

  Planets, well, yeah, yeah. So tell us about that, what do you know of it?

• 3:14Matt O'Dowd?

  So a diamond is a very, very dense form of carbon. Put carbon under a lot of pressure and those little atoms all align into that beautiful diamond lattice that we like to wear on our fingers sometimes. But planets can be...

• 3:28Neil deGrasse Tyson?

  Crystall lattice, yeah.

• 3:28Matt O'Dowd?

  Crystall lattice, exactly, yeah. Planets are sometimes massive enough that the interiors can presumably crystallize, carbon.

• 3:37Neil deGrasse Tyson?

  And carbon's not rare in the universe, so...

• 3:39Eugene Mirman?

  So there are planets, the whole planet's made of diamonds?

• 3:42Neil deGrasse Tyson?

  In fact, there's sections of the universe where it's mostly carbon. There are places where stars, in their effluences, will actually release copious amounts of carbon.

• 3:52Matt O'Dowd?

  It's a super common material.

• 3:53Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 3:54Matt O'Dowd?

  So, I mean, the planets would be, the diamond would be inside. You need to get that pressure, and so you need a bunch of stuff on top, so there'd be carbon outside.

• 4:01Eugene Mirman?

  I knew it.

• 4:02Neil deGrasse Tyson?

  You gotta dig for it.

• 4:03Eugene Mirman?

  Planet...

• 4:04Matt O'Dowd?

  Well, not all carbon, not all diamond. And the other thing is diamonds aren't that rare anyway, even on Earth. I think we, you know...

• 4:10Eugene Mirman?

  I idolize them too much?

• 4:12Matt O'Dowd?

  Yeah, I mean, they're not that uncommon.

• 4:14Neil deGrasse Tyson?

  Wait, cool, so we got the diamond, and like I said, in New York City, there are no reptiles the size of buildings. But if you live in a small town, you know, T-Rex would be bigger than your house.

• 4:23Matt O'Dowd?

  Although, I know you know this because I think you assembled the T-Rex skeleton yourself at the museum. I didn't know.

• 4:30Neil deGrasse Tyson?

  It was a kit, you put it together.

• 4:32Matt O'Dowd?

  Exactly. Well, so reptiles descended from the same ancestor as dinosaurs, but dinosaurs themselves...

• 4:38Neil deGrasse Tyson?

  You mean, modern reptiles, yeah.

• 4:39Matt O'Dowd?

  Yeah, and were not reptiles, as far as I understand. They are basically closely related to birds. In fact, birds are dinosaurs, really.

• 4:47Neil deGrasse Tyson?

  Aren't birds more closely related to the dinosaurs than modern reptiles are?

• 4:51Matt O'Dowd?

  My understanding, really from the phylogenetic tree at the American Museum of Natural History, is that birds and dinosaurs are really the same thing. Birds are the only surviving.

• 5:02Neil deGrasse Tyson?

  My issue was that reptiles, that's what I'm saying. So, everyone's talking about birds being the descendants of dinosaurs without mentioning the crocodile. And is that true? Is that... I don't know.

• 5:11Eugene Mirman?

  Crocodile is the worst bird.

• 5:13Matt O'Dowd?

  It is, yeah.

• 5:15Eugene Mirman?

  Famously terrible bird.

• 5:16Neil deGrasse Tyson?

  Neither of us is a paleobiologist. But, so all I can say is, I don't... There were never dinosaurs the size of New York City buildings, that's all I'm saying.

• 5:26Matt O'Dowd?

  And all I want to say is, is there a limit to this universe? I would say absolutely yes, in that not everything that can exist does, but so many things...

• 5:37Neil deGrasse Tyson?

  But how do you know that?

• 5:39Matt O'Dowd?

  It's an educated guess. I think the laws of...

• 5:41Neil deGrasse Tyson?

  Name something that can exist that you think doesn't.

• 5:44Matt O'Dowd?

  Name something that can exist. Well, for example, the mathematics of, say, of relativity describe things like wormholes and, you know, quantum mechanics has its tachyons. These...

• 6:00Eugene Mirman?

  You're saying Star Trek isn't real?

• 6:03Eugene Mirman?

  Wait, what? Like if I admit I can't emit a tachyon pulse?

• 6:07Matt O'Dowd?

  I would say an infinite universe contains an infinite number of things, but it doesn't contain everything that you can imagine. I'd say the laws of physics still have to be obeyed.

• 6:18Neil deGrasse Tyson?

  Well, so I'm with you on that. So, you're not gonna have an Empire State Building-sized reptile.

• 6:23Matt O'Dowd?

  Exactly.

• 6:24Neil deGrasse Tyson?

  Because it can't hold itself up.

• 6:25Matt O'Dowd?

  Exactly.

• 6:25Neil deGrasse Tyson?

  With a very interesting... So, you know about this? They teach this... I don't think they teach this outside of, like, Physics 101. But, so, so as you get bigger...

• 6:33Eugene Mirman?

  Yeah.

• 6:34Neil deGrasse Tyson?

  Your volume grows...

• 6:39Neil deGrasse Tyson?

  Your weight goes up according to your volume. Yeah. But the strength of your limbs. Mm hmm. Goes up only according to this cross sectional area. So it's a matter of area versus volume.

• 6:50Eugene Mirman?

  So Godzilla is.

• 6:51Neil deGrasse Tyson?

  Godzilla would collapse under his own weight into a puddle of guts. Yes, correct.

• 6:57Eugene Mirman?

  Even if it was irradiated, just because.

• 7:00Neil deGrasse Tyson?

  Oh, he was irradiated.

• 7:02Eugene Mirman?

  Is that helpful?

• 7:02Neil deGrasse Tyson?

  That that that changes the volume area thing completely. Right, right.

• 7:06Eugene Mirman?

  Doesn't it affect it at all?

• 7:07Neil deGrasse Tyson?

  So it's why the it's why big animals, heavy animals have thicker legs. You can't so you can't just scale up an insect and make them this big. Because their body.

• 7:18Eugene Mirman?

  That is great news.

• 7:20Neil deGrasse Tyson?

  That's good.

• 7:20Eugene Mirman?

  First of all, that is very good.

• 7:22Neil deGrasse Tyson?

  Yeah, yeah, and it and it completely negates half the horror movies of the nineteen fifty.

• 7:26Eugene Mirman?

  Point so far the ant was gigantic, it was.

• 7:28Neil deGrasse Tyson?

  That would have to be a lot stubbier. They would have to be serious cankles to be able to. So as the ant gets bigger, the body weight goes so much grows faster than the strength of its spindly legs can support it. And it would just collapse under its own weight. So you can't just scale up insects and get big insects. It's just not gonna happen.

• 7:49Eugene Mirman?

  Well, I'm gonna remove that as a fear I had.

• 7:50Neil deGrasse Tyson?

  Because so the laws of physics prevent that. Which is why you can't have Godzilla.

• 7:55Eugene Mirman?

  Right.

• 7:55Neil deGrasse Tyson?

  As as big as Godzilla is.

• 7:56Eugene Mirman?

  How big could a person be? Like, could you have a giant person that's the size of a building?

• 8:00Neil deGrasse Tyson?

  A small. No, no, no, I'm talking about any kind of life.

• 8:03Eugene Mirman?

  Any kind of life.

• 8:03Neil deGrasse Tyson?

  Right, right, right. Right, plus.

• 8:05Eugene Mirman?

  So we don't need to fear like giant elephants or King Kong.

• 8:08Neil deGrasse Tyson?

  Plus, there's another thing that involves blood pressure.

• 8:12Eugene Mirman?

  Uh huh.

• 8:12Neil deGrasse Tyson?

  Okay, so if you're really, really big and you have to get blood to your brain, if your brain is at the top, you would need a seriously pumping valves to do this.

• 8:21Eugene Mirman?

  Well, if you had a heart, though, that was the size of a house inside your body that's the size of a skyscraper, would that be fine?

• 8:29Neil deGrasse Tyson?

  I mean, that could pump with that kind of energy. Yeah, I guess so. I mean.

• 8:32Eugene Mirman?

  Well, you'd need maybe two or three hearts, is what we're saying. If you wanted to be the size of a.

• 8:37Neil deGrasse Tyson?

  He's inventing the creature here. But but but.

• 8:39Eugene Mirman?

  I'm just adding a heart to a giant thing that doesn't exist. I think that's fair.

• 8:43Matt O'Dowd?

  I think part of the problem is these things evolved from smaller versions. And so they have to kind of co-opt those miniature organs to something that works on the large scale.

• 8:53Neil deGrasse Tyson?

  They didn't come out of the box big.

• 8:54Matt O'Dowd?

  Yeah, exactly.

• 8:55Eugene Mirman?

  So the biggest creature that ever existed is how like.

• 8:58Neil deGrasse Tyson?

  No, it is the blue whale that exists today.

• 9:01Eugene Mirman?

  Great.

• 9:02Neil deGrasse Tyson?

  So what's fascinating to me is that mammals have some of the widest size range of any branch in the tree of life.

• 9:09Matt O'Dowd?

  What is the smallest mammal?

• 9:11Neil deGrasse Tyson?

  It's like it's like it's like this big. There's a little.

• 9:14Eugene Mirman?

  You could eat it for sure.

• 9:17Matt O'Dowd?

  Like as an obdurate, yeah.

• 9:18Eugene Mirman?

  Yeah.

• 9:19Neil deGrasse Tyson?

  But you go from this to the blue whale. Now here's where the blue whale cheats. You look up blue whale in the book. It's a whale weighs four gazillion tons.

• 9:26Eugene Mirman?

  Yeah.

• 9:27Neil deGrasse Tyson?

  Not really.

• 9:28Eugene Mirman?

  Because gazillion isn't a number?

• 9:29Neil deGrasse Tyson?

  Well, no.

• 9:32Neil deGrasse Tyson?

  Not only for that reason, but it's actually floating in water.

• 9:36Matt O'Dowd?

  Right, cheating.

• 9:36Neil deGrasse Tyson?

  It is not holding up that weight. And so, once you are in water, then there is no limit to your mass.

• 9:45Eugene Mirman?

  Wait, so could Godzilla exist but only in water?

• 9:47Neil deGrasse Tyson?

  Godzilla loves being in the water.

• 9:49Matt O'Dowd?

  Exactly.

• 9:49Eugene Mirman?

  And he couldn't then exist, so it's.

• 9:50Neil deGrasse Tyson?

  But he couldn't have come out of the water and start terrorizing the town. In the same way, a crocodile is basically useless on the ground. A crocodile has to do a push-up just to walk and then go back down because his legs are not directly under it, which is a big evolutionary advance. I don't need muscles to hold up my body weight because vertically, I'm just I'm just supported.

• 10:14Eugene Mirman?

  So to redo this, Godzilla can exist but not out of the water?

• 10:17Neil deGrasse Tyson?

  It has to go into the water. That's right. And that's why huge clumsy things are can be highly nimble swimming in the water.

• 10:24Matt O'Dowd?

  Giant squids or jellyfish would just be a sack of.

• 10:27Neil deGrasse Tyson?

  Yeah, yeah, exactly.

• 10:29Eugene Mirman?

  Yeah, okay, great.

• 10:30Neil deGrasse Tyson?

  All right.

• 10:31Eugene Mirman?

  We learned a lot. Thanks.

• 10:32Neil deGrasse Tyson?

  And that was from whom?

• 10:33Eugene Mirman?

  That was from Jordan Thompson.

• 10:35Matt O'Dowd?

  Thanks, Jordan.

• 10:36Eugene Mirman?

  Yeah. Um, Susan.

• 10:38Neil deGrasse Tyson?

  Was that a Patreon question?

• 10:39Eugene Mirman?

  No, it was Instagram.

• 10:40Neil deGrasse Tyson?

  Okay.

• 10:41Eugene Mirman?

  Um, these are all sort of largely Facebook and Instagram. So this one's from.

• 10:44Neil deGrasse Tyson?

  We're supposed to read Patreon questions first because they like give us money and they bribe us to read their questions.

• 10:49Eugene Mirman?

  First of all, I'm totally with you excluding the part where I have no questions from Patreon.

• 10:53Neil deGrasse Tyson?

  Okay.

• 10:54Eugene Mirman?

  So I can make them up.

• 10:56Neil deGrasse Tyson?

  Okay. All right, go on.

• 10:58Eugene Mirman?

  If that's.

• 10:58Neil deGrasse Tyson?

  Because that's how that's how you can bribe us.

• 11:00Eugene Mirman?

  Yeah, yeah. No, I agree.

• 11:02Neil deGrasse Tyson?

  Mm-hmm.

• 11:02Eugene Mirman?

  Um, Susan Minogue from Facebook asks.

• 11:06Eugene Mirman?

  How sure are we about our map of our galaxy and the universe in general? Could our tools, techniques, be mapping an illusion and that the universe is much smaller or larger than we've calculated?

• 11:20Neil deGrasse Tyson?

  Your show is called Spacetime.

• 11:24Eugene Mirman?

  Is everything we know based on lies?

• 11:27Matt O'Dowd?

  I mean, it could just be that there's a giant dome that's painted kind of like the Wizard of Oz set.

• 11:35Eugene Mirman?

  Right. Are we in a super complicated Truman Show?

• 11:38Matt O'Dowd?

  I think the closest thing to that is the idea of the holographic universe where you have this vastly distant shell that's a hologram and that our three dimensions are projected from two. Highly, highly hypothetical, I'm even gonna say theoretical. So, all right, how do we measure this stuff? With many scientists working independently, making measurements independently, and getting agreed upon results. In the case of the map of our universe is pointing multiple different telescopes at distant galaxies and, you know, basically calculating redshifts and, but also getting distances by different independent methods.

• 12:18Neil deGrasse Tyson?

  So I would add that we use a regular telescope that is sensitive to visible light, and that's the extension of our retina, and we see a galaxy there. Now, somebody else invents an infrared telescope, or a microwave telescope, or a radio telescope, and we scan the sky, we find the same object, but now emitting in these other bands. So, this gives us confidence that the object is real, that it's actually there, and some interesting things are happening in it. And that it's not, and then, like, as you were saying before I interrupted you, that you can get the distance to this object by multiple ways, they're not standard ways you would measure distances on Earth. On Earth, you can pace out the distance, you can get a little tape measure, you can use now one of these...

• 13:00Eugene Mirman?

  Like a wheel?

• 13:02Neil deGrasse Tyson?

  Laser thingies. So, there are multiple ways. If you get the same answer from all those ways, and all those ways are completely different from one another, you have confidence you have the right distance to the object. And so, yeah, so this, you combine all of these factors, we think the universe is real, and it is what we measure it to be. But you can take a deeper philosophical point, that there is no reality beyond the measurement.

• 13:31Neil deGrasse Tyson?

  The measurement becomes the reality of the universe that we describe. So to say it really is this other thing, you're just not measuring it to be, so I'll say, "How will you ever know that it's this other thing?"

• 13:45Eugene Mirman?

  Well, I don't know. The question wouldn't be that it's another thing, it's just that we are wrong.

• 13:48Neil deGrasse Tyson?

  Well, how would you know that we are wrong? There's, so, so we learn in quantum physics.

• 13:54Eugene Mirman?

  You learn in quantum physics.

• 13:56Neil deGrasse Tyson?

  The, the, the reality of the world only makes sense through the measurement.

• 14:04Matt O'Dowd?

  Right, in a sense, yeah.

• 14:05Neil deGrasse Tyson?

  Yeah, in a sense. So you cannot, it, it doesn't mean anything to talk about a world that is outside of a measurement.

• 14:16Matt O'Dowd?

  So, that's what, that's what, that's what Niels Bohm would say.

• 14:18Neil deGrasse Tyson?

  You have no access to it.

• 14:19Matt O'Dowd?

  I think, I think, I think others, I think, you know, for example, David Bohm and, and, and realists would, would argue otherwise. I think the important thing is not to confuse, though, the idea that the, you know, we have a subjective experience of the universe. And that, that subjective experience isn't the universe, it's a different thing to the actual universe. And, um, but nonetheless, the universe remains consistent. Our subjective experience of the universe matches other people's subjective experience. We can all make measurements that agree with each other. And that gives us confidence that there is something objectively real out there, even if we can't say exactly what it is.

• 14:56Neil deGrasse Tyson?

  And I would add to that, but I'll tie a bow on it, that I look at something and I say, "Okay, that looks red to me. Well, am I on drugs or not?" Okay, so that, so that'd be a subjective reality. So then you devise an experiment. So you have an apparatus that measures wavelengths of light. And you've already calibrated it to that this wavelength is a red over here. So now you come to this, and the machine measures red as well.

• 15:18Eugene Mirman?

  Is the machine on drugs?

• 15:20Neil deGrasse Tyson?

  You're gonna teach, you're gonna teach the machine what red means first. We have to teach it over here what red is. And then we look at this thing that I'm looking at. And so now, we both... Query the machine, what color is this? And the machine gives us the same answer. So I've removed my own brain from this experiment, and I'm getting the same answer. So, to a limit, our subjective experience is reality, but we know the limits of our subjective experience. And the whole point of science is to probe reality, reducing our subjective interpretation by as much as is humanly possible, ideally to zero.

• 15:57Matt O'Dowd?

  Yeah, or refining the subjective model so that it better and better predicts the objective reality, even though it will never be the objective reality. It's a highly effective predictive, you know, apparatus.

• 16:09Neil deGrasse Tyson?

  Mm-hmm.

• 16:10Eugene Mirman?

  Okay.

• 16:10Neil deGrasse Tyson?

  All right.

• 16:11Eugene Mirman?

  Next question.

• 16:11Neil deGrasse Tyson?

  I think we have time for like one more question.

• 16:12Eugene Mirman?

  Okay.

• 16:13Neil deGrasse Tyson?

  In this segment. All right, what do you got?

• 16:14Eugene Mirman?

  From Leo Zua, Zusa, on Instagram. How about the recent articles about the possibility of us being part of a simulation and the Big Bang being just the seeding event of such simulation? Thanks!

• 16:27Neil deGrasse Tyson?

  I'm totally there.

• 16:28Eugene Mirman?

  Yeah.

• 16:29Neil deGrasse Tyson?

  I'm digging it every minute of it. You don't like it?

• 16:30Matt O'Dowd?

  Yeah?

• 16:31Neil deGrasse Tyson?

  I'm loving it!

• 16:32Matt O'Dowd?

  I want to hear your opinion on this.

• 16:33Neil deGrasse Tyson?

  I'm loving it!

• 16:33Matt O'Dowd?

  I want to hear this.

• 16:34Neil deGrasse Tyson?

  I'm loving it!

• 16:35Eugene Mirman?

  Well...

• 16:36Matt O'Dowd?

  So who made the simulation?

• 16:37Neil deGrasse Tyson?

  Some snot-nosed kid in the parents' basement of an alien civilization. Who's bored, and they're more advanced than we are, and they have way more computing power than we are.

• 16:49Matt O'Dowd?

  Right, so it's like a little handheld Nintendo you can use.

• 16:52Neil deGrasse Tyson?

  Exactly. And so they program in enough detail to completely simulate every molecule in this universe, and we are here for their entertainment. Why else can you explain, where things are going along just fine in the world, that all of a sudden, there's a complete disruption?

• 17:07Matt O'Dowd?

  The snot-nosed kid?

• 17:08Neil deGrasse Tyson?

  Culturally, politically, economically, a complete disruption. I think that's, they throw it in for entertainment. That's what I think.

• 17:15Matt O'Dowd?

  Okay. I'm going to say, I have two things to say. Firstly... I predict that you don't believe that. That's my first prediction.

• 17:22Neil deGrasse Tyson?

  Okay.

• 17:22Matt O'Dowd?

  But I don't want to put thoughts in your head.

• 17:26Neil deGrasse Tyson?

  There's an argument for why that that's more likely than any other scenario. I'll tell you that in a minute.

• 17:31Matt O'Dowd?

  The numbers game, okay? So the idea that if you, if you, you need to produce one universe capable of producing universe simulations.

• 17:38Neil deGrasse Tyson?

  And that's all you need.

• 17:38Matt O'Dowd?

  And if that universe produces billions of universe simulations, then any universe that you happen to find yourself in.

• 17:44Neil deGrasse Tyson?

  Is more likely to simulate than the one universe that started at all.

• 17:48Eugene Mirman?

  Well, meaning if the way that like virtual reality now exists and, you know, video games have advanced, it is likely that in say a thousand years, whatever our virtual reality would be.

• 17:57Neil deGrasse Tyson?

  Or thirty years.

• 17:58Eugene Mirman?

  Thirty years.

• 17:59Neil deGrasse Tyson?

  A thousand or thirty.

• 18:00Eugene Mirman?

  Well, thirty years, that whatever it was would potentially be physical, like you could, you would be able to feel it.

• 18:06Matt O'Dowd?

  Okay, so.

• 18:06Neil deGrasse Tyson?

  No, no, no. It wouldn't, it doesn't even require that. It just requires that what you program in there has an, in your Nintendo, whatever it is, has enough complexity that in the mind of the characters in that game, they think they're real.

• 18:21Matt O'Dowd?

  Right, so.

• 18:21Neil deGrasse Tyson?

  And their free will.

• 18:22Matt O'Dowd?

  It can't simulate the whole universe, because to simulate a universe perfectly, you need a computer the size of a universe.

• 18:27Neil deGrasse Tyson?

  Do you?

• 18:27Eugene Mirman?

  Do you?

• 18:28Matt O'Dowd?

  Yes.

• 18:29Eugene Mirman?

  I don't know.

• 18:30Matt O'Dowd?

  Because, I mean, assuming it's a perfect.

• 18:33Neil deGrasse Tyson?

  Dip, dip, dip, dip. I do want to hear, but we gotta take a break.

• 18:36Eugene Mirman?

  I want to hear it.

• 18:37Matt O'Dowd?

  I have so much to say. So much to say.

• 18:39Neil deGrasse Tyson?

  When we come back, more of this Cosmic Curie on StarTalk.

• 18:50Neil deGrasse Tyson?

  We're back on StarTalk. We've got the guest Tyson Eugene Mirman.

• 18:55Eugene Mirman?

  Hello.

• 18:55Neil deGrasse Tyson?

  Back in the house. Eugene, you too, by what handle?

• 18:58Eugene Mirman?

  Uh, at Eugene Mirman.

• 19:00Neil deGrasse Tyson?

  At Eugene Mirman. You got it. And I've got a friend and colleague, Matt O'Dowd, who, who is, uh, he's an associate up at the American Museum of Natural History, my day job, where I serve as director of the planetarium. But he's, he's an affiliate of ours and a professor of his own up at Leamie College in New York.

• 19:20Matt O'Dowd?

  That's right.

• 19:20Neil deGrasse Tyson?

  So, welcome. And you've got your own YouTube channel. I'm jealous. You've got a good YouTube channel?

• 19:25Matt O'Dowd?

  Well, my, my team's YouTube channel, I would say.

• 19:27Neil deGrasse Tyson?

  Okay, that's good.

• 19:28Matt O'Dowd?

  PBS Digital Studios.

• 19:29Neil deGrasse Tyson?

  PBS Digital Studios, very good. Titled Spacetime.

• 19:32Matt O'Dowd?

  Exactly.

• 19:32Neil deGrasse Tyson?

  And we left off before the break. You asserting to my disagreement that you need a computer the size of the universe to program the universe, and I'm saying that the universe that's created doesn't have to be the whole universe. It can be just some other universe. It can be whatever less than the original universe needs to be to be whatever it is where they think it's their whole universe.

• 19:57Matt O'Dowd?

  That I agree with.

• 19:58Neil deGrasse Tyson?

  Okay, good.

• 19:59Matt O'Dowd?

  That I agree with. We have no discussion.

• 20:01Neil deGrasse Tyson?

  We agree. Let's go for a beer.

• 20:03Matt O'Dowd?

  I do have one thing to say. So this whole idea recently came up. I think it got a bit of oomph because Elon Musk asserted that this was quite likely that we were part of a simulation.

• 20:15Neil deGrasse Tyson?

  By the way, just to be clear, this thought did not originate with him.

• 20:19Matt O'Dowd?

  Of course not.

• 20:20Neil deGrasse Tyson?

  It goes back to the 90s, and there are a few philosophers who started, who set this ball rolling, and then many others, many others.

• 20:28Matt O'Dowd?

  And one of those writers, whose name I'm blanking on.

• 20:31Neil deGrasse Tyson?

  Pearl Jam?

• 20:32Matt O'Dowd?

  It might have been Pearl Jam. So the idea was that we are most likely in what he called.

• 20:38Neil deGrasse Tyson?

  You gotta know your groups and when they peaked. This is good. This is good, Eugene.

• 20:43Matt O'Dowd?

  So the idea is an ancestor simulation, the idea that some future version of ourselves, when we're more advanced.

• 20:48Neil deGrasse Tyson?

  Nick Bostrom is one of the original thinkers of this, I think. Okay, but go on.

• 20:52Matt O'Dowd?

  The idea was that in the future, scientists or kids with Nintendo would choose to simulate the entire mental life of ancestors, you know, from hundreds of years ago, just as a study, as a study in parapsychology. But that's all they have to do. They have to simulate only the activity of the mind and input all of the senses as long as they're consistent. Now, that probably will be able to do. I mean, the brain doesn't have that many connections that we can't, you know, in a couple of Moore's Law doublings, sort that out. The problem with.

• 21:24Neil deGrasse Tyson?

  I recently heard that Moore's Law is now no longer 18 months, it's three years.

• 21:28Matt O'Dowd?

  Until we hit the next, I guess, iteration of, once we move beyond silicon, maybe.

• 21:34Neil deGrasse Tyson?

  I'm just saying, I heard it.

• 21:36Matt O'Dowd?

  Yeah, you have to run.

• 21:37Neil deGrasse Tyson?

  By top people.

• 21:38Eugene Mirman?

  Sure.

• 21:39Neil deGrasse Tyson?

  I cannot.

• 21:39Matt O'Dowd?

  This might, this might take.

• 21:40Eugene Mirman?

  Very good people.

• 21:41Neil deGrasse Tyson?

  Top people.

• 21:42Eugene Mirman?

  Great.

• 21:44Neil deGrasse Tyson?

  Okay, so now, so where are you going with this?

• 21:46Matt O'Dowd?

  So the idea is it's not simulating a universe as you, as you suggested. But I think it, I think it requires a lot of assumptions that, that future us will want to simulate the entire mental life of our ancestors and, and that we're more likely to be that. But my main objection is that part of the idea is that if something goes wrong, for example, we figure out we're part of the simulation.

• 22:05Eugene Mirman?

  Mm-hmm.

• 22:06Matt O'Dowd?

  Then whoever's running the simulation can edit it and remove that thought and business as usual.

• 22:13Neil deGrasse Tyson?

  Sure.

• 22:14Matt O'Dowd?

  And so it's the most useless hypothesis.

• 22:16Neil deGrasse Tyson?

  The people who disappear and no one knows where they are.

• 22:19Matt O'Dowd?

  But that would.

• 22:19Neil deGrasse Tyson?

  Stuff happens in our lives.

• 22:20Matt O'Dowd?

  But that would be, but that would be.

• 22:22Eugene Mirman?

  We blame the Russians.

• 22:22Matt O'Dowd?

  That would be.

• 22:23Eugene Mirman?

  But actually.

• 22:24Matt O'Dowd?

  That would be.

• 22:25Eugene Mirman?

  It's just some kid.

• 22:25Neil deGrasse Tyson?

  You've had thoughts that popped into your head today that you never had in the previously in your life.

• 22:31Matt O'Dowd?

  So there's no way, there's no way that the conspiracy can be proved or denied because everything's programmed, including, you know, evidence that we see that it is true, people disappearing, you know, Roswell, all of this stuff is presumably programmed in. So I reject it because I think we need to continue on as though it's not true.

• 22:52Eugene Mirman?

  Well, you could do both. You could be like, well, maybe we're a simulation, but we should clearly live life as if we're people.

• 22:57Neil deGrasse Tyson?

  As though we have free will.

• 22:59Eugene Mirman?

  We would also still like, even in a simulation, if you murdered someone, you'd go to simulation jail, which I'm sure is terrible.

• 23:05Matt O'Dowd?

  That's true.

• 23:05Eugene Mirman?

  Yeah.

• 23:06Matt O'Dowd?

  I don't know.

• 23:07Eugene Mirman?

  All right, next question.

• 23:08Neil deGrasse Tyson?

  All right.

• 23:10Eugene Mirman?

  BigDogD1223 asks, if Venus doesn't have a magnetic field, then how does it keep its thick atmosphere? Shouldn't it end up like Mars?

• 23:21Matt O'Dowd?

  That's a good one.

• 23:23Neil deGrasse Tyson?

  So one of the things that keeps our magnetic field stoked.

• 23:27Eugene Mirman?

  Yeah.

• 23:27Neil deGrasse Tyson?

  Is that down in our sort of semi-molten iron core, you get carp, you get iron sort of moving. If you have, and, and Earth is spinning. And so since we spin it at relative, once a day.

• 23:43Eugene Mirman?

  Yeah.

• 23:43Neil deGrasse Tyson?

  It's relatively fast, much faster than Venus.

• 23:47Eugene Mirman?

  How fast does Venus spin?

• 23:48Neil deGrasse Tyson?

  Like a little less often than once a year.

• 23:51Matt O'Dowd?

  And, and in the wrong direction.

• 23:53Neil deGrasse Tyson?

  Right.

• 23:53Eugene Mirman?

  Oh, what a dumb planet. You can have that as a book title.

• 23:58Neil deGrasse Tyson?

  Yeah, what a double. So you are fewer, you are fewer days old on Venus than you are years. So that's, so it's not churning, you know, you don't get this sort of what they call differential rotation. So, so Venus, right, does not have a significant magnetic field. The magnetic field protects you from the ablative effects of the solar wind. And so there's Venus, closer to the sun, getting twice the flux of solar wind than we get. And it maintains its atmosphere. So generally, when we, what, what goes on here on Earth is, it's not that it will blow away our atmosphere. It's that if there's a water molecule high up, H2O,

• 24:44Neil deGrasse Tyson?

  the energy from the sun can break apart that water molecule, separate the hydrogen from it, then you lose the hydrogen.

• 24:49Matt O'Dowd?

  But I think, I think part of it is also that Mars is much, much lighter than Venus. And so Venus is almost as massive, massive as the Earth.

• 24:56Neil deGrasse Tyson?

  Yes, there were twins.

• 24:57Matt O'Dowd?

  It holds on to its atmosphere. And, you know, the, it has so much of it. It's, it's got to be losing stuff, but the time scale is just much, much longer.

• 25:06Neil deGrasse Tyson?

  Right. And it's got nearly a hundred times the atmospheric pressure as Earth, so.

• 25:10Eugene Mirman?

  From, how, how is that?

• 25:12Neil deGrasse Tyson?

  Well, so if you go there, you would, you'd be crushed split seconds before you vaporized.

• 25:19Matt O'Dowd?

  Is that the order?

• 25:20Eugene Mirman?

  Why is it, why is it the other way around?

• 25:23Neil deGrasse Tyson?

  I don't know the full, the full origin of that.

• 25:25Eugene Mirman?

  Right.

• 25:25Matt O'Dowd?

  It's got a lot more of it.

• 25:26Eugene Mirman?

  Well, I'm not going there.

• 25:28Matt O'Dowd?

  The, the record for a, a lander on, on Venus is something like two, three hours before it crumpled in like a.

• 25:34Neil deGrasse Tyson?

  Yeah, and, and, and the big Venus people were the Russians. They, they had the Venere spacecraft.

• 25:40Eugene Mirman?

  And they sent it and they got some info and then got crushed?

• 25:43Neil deGrasse Tyson?

  Yeah, you get crushed and it melts. It's, they knew this, but it was, it's still a challenge. While we were going to Mars, they were going to Venus.

• 25:49Eugene Mirman?

  Right. Did we go to Mars because it's super easy?

• 25:53Neil deGrasse Tyson?

  It's actually hard. Mars is hard.

• 25:55Matt O'Dowd?

  Venus is closer.

• 25:55Neil deGrasse Tyson?

  But a quick thing, so, um, while we're on the subject, I, uh, allow me to, uh, tell you the story of Venus.

• 26:04Eugene Mirman?

  Sure.

• 26:05Neil deGrasse Tyson?

  Oh, okay.

• 26:06Eugene Mirman?

  I was gonna say, do you know the story of Venus?

• 26:07Neil deGrasse Tyson?

  I know the story of Venus.

• 26:08Eugene Mirman?

  Great.

• 26:09Neil deGrasse Tyson?

  So. You know, if you're from Mars, you're Martian. If you're from Earth, you're an Earthling. From Venus, you're Venusian. You know, we have these words if you are of those places.

• 26:21Eugene Mirman?

  Yeah.

• 26:22Neil deGrasse Tyson?

  It turns out Martian is X is correct. Earthling is good. But Venusian, that's an improperly formed word. We're stuck with that word because the properly formed word was already taken by a whole other branch of science. The medical doctor. If you are of Venus, you are Venereal.

• 26:44Matt O'Dowd?

  Oh, from the Latin.

• 26:46Neil deGrasse Tyson?

  From the Latin, exactly. That's the genitive form of Venus. And so when doctors found diseases peculiar to lovemaking, and Venus being the goddess of love and beauty, they said, "Listen, name it all after Venus."

• 26:59Eugene Mirman?

  Right.

• 26:59Neil deGrasse Tyson?

  So that became the category Venereal.

• 27:02Eugene Mirman?

  And aliens were like, "We would rather you didn't call us Venereal."

• 27:04Neil deGrasse Tyson?

  Right, exactly. They're pissed off ever since. So we should not be surprised that the spacecraft the Russians sent to Venus were all called the Venera series. And it's because of that genitive form.

• 27:16Matt O'Dowd?

  So war wounds should be Martian? Like that's a Martian cortusian you receive.

• 27:22Neil deGrasse Tyson?

  Yeah, that's if you want to be, yeah, if you want to be symmetric about that, consistent. Yeah, you have a Martian wound. Yeah, yeah, very bad wound.

• 27:29Matt O'Dowd?

  Let's try to make that happen.

• 27:30Neil deGrasse Tyson?

  Yeah, alright.

• 27:34Eugene Mirman?

  Nelsen from Syracuse in upstate New York.

• 27:38Neil deGrasse Tyson?

  You're almost as bad as Chuck Nice at this. He mangles the names every single time.

• 27:43Eugene Mirman?

  I'm not mangling anything.

• 27:44Matt O'Dowd?

  People choose weird names.

• 27:46Eugene Mirman?

  Yeah, meaning like people's like monikers, which isn't a word.

• 27:50Matt O'Dowd?

  I had a space-time commenter called Sssss. Well, I think I pronounced it correctly.

• 27:54Eugene Mirman?

  Yeah.

• 27:55Matt O'Dowd?

  Spelled S, space SS. And we have an obligation.

• 27:59Eugene Mirman?

  I feel like I read BigDogD1223 quite accurately.

• 28:04Neil deGrasse Tyson?

  You did justice to BigDogD12223.

• 28:06Eugene Mirman?

  Alright, so Nelsen. Also accurate from Syracuse asks, "Do scientists and theorists have any idea how much time passed before the Big Bang? Was there time before the Big Bang?"

• 28:18Neil deGrasse Tyson?

  I can't answer that.

• 28:19Matt O'Dowd?

  Yeah, I know.

• 28:20Neil deGrasse Tyson?

  We have no frickin' idea. Okay, next one. No, what do you have? What do you got for that?

• 28:24Matt O'Dowd?

  I mean, the standard wisdom was always that time started at the Big Bang, and before that, there was no time. That was, you know, the first second happened then. But, you know, I think there's new thinking now. I think ideas like eternal inflation, so the idea that possibly this universe just nucleated out of some inflating, rapidly-expanding multiverse-type thing in which time might have some sort of existence.

• 28:49Neil deGrasse Tyson?

  Yeah, but then it would be time, there'd be a meta-time for the meta-universe, basically. Whereas our bubble surely has a beginning point.

• 28:57Matt O'Dowd?

  Sure, that one dimension.

• 28:59Neil deGrasse Tyson?

  So I don't want to get semantic on it. We can say, "Time, as we measure it, began at our beginning."

• 29:04Matt O'Dowd?

  Right.

• 29:05Neil deGrasse Tyson?

  But if we are part of this multiverse, then you should think of a multi-time

• 29:09Matt O'Dowd?

  Right.

• 29:09Neil deGrasse Tyson?

  that actually is the master clock of all...

• 29:12Matt O'Dowd?

  Yeah, or it's talk instead of chain of cause and effect. There was a cause before the Big Bang of some sort.

• 29:19Eugene Mirman?

  So like roughly an hour?

• 29:21Matt O'Dowd?

  Yes, like, you know.

• 29:23Eugene Mirman?

  Forty-five minutes?

• 29:24Neil deGrasse Tyson?

  Forty-five minutes.

• 29:24Eugene Mirman?

  I don't want to be inaccurate. All right, Mr. Findle asks, "We created tools to detect and see different wavelengths of light that our eyes can't see."

• 29:34Neil deGrasse Tyson?

  That's for damn sure.

• 29:34Eugene Mirman?

  "Are there any ideas of tools that would allow us to detect and see dark matter?"

• 29:40Matt O'Dowd?

  So many ideas, depending on what on Earth that is.

• 29:46Neil deGrasse Tyson?

  Well, first, we do see the effects dark matter has on matter.

• 29:50Eugene Mirman?

  Right.

• 29:51Neil deGrasse Tyson?

  Dark matter has gravity.

• 29:52Eugene Mirman?

  What's the effect we see?

• 29:53Neil deGrasse Tyson?

  It has gravity. That's how we know it's there.

• 29:55Matt O'Dowd?

  Stars rotating too quickly.

• 29:57Neil deGrasse Tyson?

  And I keep saying this, it shouldn't ever have been named dark matter. It should have just been called Fred, because we don't know anything about it.

• 30:04Eugene Mirman?

  Meaning it's not matter, per se?

• 30:06Neil deGrasse Tyson?

  It may be matter, maybe not. So to call it any kind of matter is misleading.

• 30:10Matt O'Dowd?

  Right.

• 30:11Neil deGrasse Tyson?

  It's presumptive. That's a better word. Thank you. And, but... What it actually is, is dark gravity.

• 30:18Matt O'Dowd?

  Mm-hmm.

• 30:19Neil deGrasse Tyson?

  That is literally true.

• 30:20Matt O'Dowd?

  Yeah.

• 30:20Neil deGrasse Tyson?

  So, so we see its effects on things. And that's pretty good. That's so that's why we all know something's happening out there.

• 30:29Matt O'Dowd?

  Yeah.

• 30:30Neil deGrasse Tyson?

  All right. So now, is there some other way we can detect it? You got any ideas?

• 30:34Matt O'Dowd?

  Depends on what it is. I mean, if it is really matter and some kind of particle, then people are all over it, so.

• 30:40Neil deGrasse Tyson?

  People are, that's the over/under on that is that it's gonna be a particle.

• 30:44Matt O'Dowd?

  Yeah, like, like some ideas is that it might, it might self-annihilate when dark matter particles find each other. And that would produce very high-energy light. Or, or other particles that we could detect here on Earth. Um, as, as, you know, little flashes of gamma rays or cosmic rays.

• 30:59Eugene Mirman?

  Is dark matter something that's far out in space? Or is there, is it near the Earth? Or is it everywhere?

• 31:04Matt O'Dowd?

  Mm.

• 31:05Eugene Mirman?

  Meaning it might be in this room?

• 31:06Neil deGrasse Tyson?

  It's certainly in this room, but dark matter is so diffuse. It's manifest only on very large scales.

• 31:12Matt O'Dowd?

  Exactly.

• 31:13Neil deGrasse Tyson?

  So it is so dominated by ordinary matter in normal situations. It's, it's this, you can live life as though it's not there.

• 31:20Eugene Mirman?

  Right.

• 31:20Neil deGrasse Tyson?

  Same with our solar system. There's no, you don't need to invoke dark matter to calculate anything that's going on anywhere around us.

• 31:26Eugene Mirman?

  But in deeper space where there's less it has.

• 31:29Neil deGrasse Tyson?

  Bigger space.

• 31:30Matt O'Dowd?

  There's more space and so it just adds up over.

• 31:32Neil deGrasse Tyson?

  Yeah, yeah.

• 31:32Matt O'Dowd?

  Over the light years.

• 31:33Neil deGrasse Tyson?

  And here's the thing. Might we ever find, if it is a particle, might we ever find a dark matter planet? Or dark matter something else? Probably not. Because not only does this dark matter stuff, Fred, not interact with us, ordinary matter. It doesn't even interact with itself. If you don't interact with yourself, you cannot coalesce and become something.

• 31:53Eugene Mirman?

  How do you know it doesn't interact with itself?

• 31:55Neil deGrasse Tyson?

  Because it would otherwise stick to itself.

• 31:57Matt O'Dowd?

  There, there's, there's, there are ideas that would allow it to.

• 32:01Eugene Mirman?

  Hang out near each other?

• 32:02Matt O'Dowd?

  To, to, I mean, to annihilate itself when it, when they interact. But it, it's so small and spread out that it just doesn't happen very often.

• 32:09Neil deGrasse Tyson?

  You think it's only a, a frequency issue?

• 32:12Matt O'Dowd?

  By some models.

• 32:13Neil deGrasse Tyson?

  Okay.

• 32:13Matt O'Dowd?

  But or it might not interact with itself.

• 32:15Neil deGrasse Tyson?

  Okay.

• 32:15Matt O'Dowd?

  That's also possible.

• 32:16Neil deGrasse Tyson?

  Right, because we, our particles, we make molecular bonds, atomic bonds.

• 32:21Matt O'Dowd?

  Yeah, so it's not going to stick to you.

• 32:22Neil deGrasse Tyson?

  So we make molecules, and then we can be this fleshy thing called humans.

• 32:25Eugene Mirman?

  Yeah.

• 32:26Matt O'Dowd?

  It's not capable of that sort of flexibility.

• 32:28Neil deGrasse Tyson?

  But it'd be really cool if they were like humanoid dark matter entities. That would be cool.

• 32:33Matt O'Dowd?

  I like the whole idea of a dark.

• 32:34Neil deGrasse Tyson?

  They'd be completely transparent, because they don't interact with light.

• 32:36Matt O'Dowd?

  They could be right here, right now.

• 32:37Neil deGrasse Tyson?

  They could be walking amongst.

• 32:38Eugene Mirman?

  They could be all around us.

• 32:39Neil deGrasse Tyson?

  Yes.

• 32:40Eugene Mirman?

  Oh, maybe that's what angels are. Okay.

• 32:42Neil deGrasse Tyson?

  Solve that.

• 32:43Eugene Mirman?

  Yep.

• 32:43Neil deGrasse Tyson?

  One more, real quick, what do you got?

• 32:44Eugene Mirman?

  Great.

• 32:45Neil deGrasse Tyson?

  Before we break.

• 32:45Eugene Mirman?

  Someone let Mike Huckabee know. Um, Justin Kenna on Instagram asks, "Is it possible for the fabric of space to be ripped or pulled apart? Could an over-expanded black hole then be the cause of a sort of Big Bang as the matter rips a hole through the fabric of space?"

• 33:04Neil deGrasse Tyson?

  I saw that episode of Doctor Who.

• 33:05Eugene Mirman?

  Yeah.

• 33:07Neil deGrasse Tyson?

  No, so I love the idea that we might rip. It's terrifying and beautiful at the same time. We're not going to rip in what we're doing now, but in the distant future, where this dark energy pressure of the vacuum is forcing an acceleration.

• 33:25Matt O'Dowd?

  Also totally named, by the way.

• 33:27Neil deGrasse Tyson?

  An acceleration of the expansion. It, that will grow exponentially. So I'm curious, might there be a day where space is expanding so rapidly that it, its, its pliability, can I keep up with what's happening to it? And it just rips instead of continuous destruction.

• 33:46Matt O'Dowd?

  Or at the very least, atomic nuclei ripped apart and, and, yeah. So my, if that's your favorite cosmic destruction.

• 33:55Neil deGrasse Tyson?

  It would be terrifying, but oh my gosh, that'd be a new thing.

• 33:59Matt O'Dowd?

  I think even cooler is vacuum decay.

• 34:01Neil deGrasse Tyson?

  Ooh.

• 34:02Matt O'Dowd?

  So the idea.

• 34:03Neil deGrasse Tyson?

  Ooh, vacuum decay. Do you want, oh.

• 34:06Eugene Mirman?

  What's vacuum decay?

• 34:07Matt O'Dowd?

  Vacuum decay is great.

• 34:08Neil deGrasse Tyson?

  Over the commercial.

• 34:09Eugene Mirman?

  Well, decide if it's great.

• 34:10Matt O'Dowd?

  It could happen any time.

• 34:11Neil deGrasse Tyson?

  Over the commercial, he'll tell you.

• 34:12Eugene Mirman?

  Okay.

• 34:14Neil deGrasse Tyson?

  When we come back, more StarTalks Cosmic Queries.

• 34:27Neil deGrasse Tyson?

  Neil deGrasse Tyson, back at you, StarTalk. Cosmic Queries Edition. Cool, please. Grab bag. I got Eugene Mirman. Eugene! Hello. We love having you. Don't stay away for so long, next time. I'll be back soon. Yeah, call me, or something. I will. Okay. Man, great to have you.

• 34:46Matt O'Dowd?

  Hey, guys.

• 34:47Neil deGrasse Tyson?

  We're at the YouTube Studios. Why? Because you have a YouTube show.

• 34:50Matt O'Dowd?

  Sure, I do.

• 34:51Neil deGrasse Tyson?

  Called Spacetime. Great name.

• 34:53Matt O'Dowd?

  Thank you very much.

• 34:54Neil deGrasse Tyson?

  Good name.

• 34:55Matt O'Dowd?

  I didn't come up with it, but yeah.

• 34:56Neil deGrasse Tyson?

  PBS Digital Studios.

• 34:58Matt O'Dowd?

  That's right.

• 34:58Neil deGrasse Tyson?

  Very good. And so, we're doing Q&A here, and something that keeps me awake at night is wondering whether the vacuum energy of the universe is stable.

• 35:10Matt O'Dowd?

  I have lost sleep.

• 35:12Neil deGrasse Tyson?

  Have you thought about...

• 35:12Matt O'Dowd?

  I have lost sleep.

• 35:13Neil deGrasse Tyson?

  You've lost sleep too?

• 35:13Matt O'Dowd?

  Last night, I lost some sleep.

• 35:14Neil deGrasse Tyson?

  How about you? Have you? I'm about to.

• 35:16Matt O'Dowd?

  We're gonna make sure you join the class.

• 35:18Neil deGrasse Tyson?

  Yeah, yeah. What is it?

• 35:19Matt O'Dowd?

  So, ah, so vacuum decay.

• 35:22Neil deGrasse Tyson?

  Yes.

• 35:23Matt O'Dowd?

  It's scarier than the big rip that might happen due to dark energy, because it could happen at any time. It could happen spontaneously. So, the idea is that, you know, the vacuum, you know, it basically, a vacuum means there's nothing in it. But actually, the vacuum has some tiny bit of energy. The fields that permeate the universe, that give rise to particles, are through the vacuum. Now, one of those fields is the Higgs field. Okay? It's what gives subatomic particles mass. The famous Higgs boson.

• 35:51Neil deGrasse Tyson?

  It's a badass particle. If you've got to be a particle... That's the one you'd be? That's the one you want to be. The god particle. The god particle.

• 35:56Matt O'Dowd?

  We've got a good nickname. We've got the best nickname.

• 35:58Neil deGrasse Tyson?

  Uh-huh.

• 35:59Matt O'Dowd?

  So, the idea is that that Higgs field...

• 36:01Neil deGrasse Tyson?

  Okay, can I give you a quick explanation for how it gives mass? Sure. I think this explanation works.

• 36:06Matt O'Dowd?

  Okay.

• 36:07Neil deGrasse Tyson?

  Okay? Think of a party in Los Angeles. Okay. In Hollywood.

• 36:11Matt O'Dowd?

  I've never been invited to one, but...

• 36:12Neil deGrasse Tyson?

  Okay, alright. And so, what the Higgs field does is, it will create a resistance to your ability to move through that field, depending on what kind of particle you are. And the greater is that resistance, the more you measure its mass-to-be. Okay? Because massive things don't move quickly. So, you go to a party in Los Angeles, and somebody nobody has heard of walks in. Okay? Arnold Schmednick. Okay? Fine. Walks in. No one crowds around him. He can go straight to the bar. Has very low party mass. Beyonce walks in, then a scrum builds around her.

• 36:55Neil deGrasse Tyson?

  She cannot move because people are taking selfies, getting autographs, asking her questions, paparazzi. She moves five inches a minute. Takes her a half hour to get across the thing. She has very high party mass. The party field granted her more mass than Arnold Schmegg.

• 37:13Matt O'Dowd?

  So Arnold is a neutrino and Beyonce is a... It's a massive particle.

• 37:17Neil deGrasse Tyson?

  Exactly, yeah, okay, good.

• 37:19Matt O'Dowd?

  So the universe is...

• 37:20Neil deGrasse Tyson?

  Did you get your approval on that analogy?

• 37:21Matt O'Dowd?

  I think it's good. I think it's a great start. And I direct everyone to an episode on spacetime we've done this subject that takes it only a tiny little bit further.

• 37:30Neil deGrasse Tyson?

  Okay, alright, good, good.

• 37:32Matt O'Dowd?

  But, the cool thing about the Higgs field...

• 37:34Neil deGrasse Tyson?

  I think you just dissed my example.

• 37:35Matt O'Dowd?

  No, I love this.

• 37:36Eugene Mirman?

  Well, here's what I...

• 37:37Matt O'Dowd?

  Only because I've never been invited to that party and I know that I passed through. I know.

• 37:41Eugene Mirman?

  Tell me about the vacuum that I need to be afraid of.

• 37:44Neil deGrasse Tyson?

  Okay.

• 37:45Eugene Mirman?

  Please.

• 37:46Matt O'Dowd?

  So the Higgs field works because it has a non-zero energy everywhere. There's a little bit of Higgs-iness everywhere in the universe.

• 37:53Eugene Mirman?

  Yeah.

• 37:53Matt O'Dowd?

  This little field that goes jujuju, it'll throw a volume of space.

• 37:56Eugene Mirman?

  That's how I describe it.

• 37:57Matt O'Dowd?

  Right, yeah.

• 37:57Neil deGrasse Tyson?

  And just to be clear, because in case anyone who's watching this is really young and the only concept of a vacuum is a machine that's sitting in the closet.

• 38:06Eugene Mirman?

  Right.

• 38:06Neil deGrasse Tyson?

  So that machine creates a vacuum, hence we call them vacuums, right? So, in space, unlike, who was it that said it? Nature abhors a vacuum only on the surface of the earth. Most of the universe is vacuum. So, the universe loves itself some vacuum. Okay, so...

• 38:26Matt O'Dowd?

  It's a region where there's nothing, except there isn't nothing, there's some little Higgs energy.

• 38:30Neil deGrasse Tyson?

  Exactly, go on.

• 38:31Matt O'Dowd?

  Right. And so when the universe was settling down, soon after the Big Bang, that Higgs energy found a nice, comfortable place to be.

• 38:41Neil deGrasse Tyson?

  To rest.

• 38:41Matt O'Dowd?

  A value to take. And you can sort of think of it as it was falling downhill in energy and it found a nice dip in the energy that it could be and came to rest at that particular energy. But over that little hump, there may be a deeper drop and a much more preferential, comfortable, lower energy for the Higgs field to take. The vacuum, if it could get to that lower energy point, it would go there because the universe, one thing the universe does love to do is be in a low-energy state. That's something it will do whenever it can. But it needs to realize that over that little hump, that low-energy state is there. It only takes one little part of the universe to get the message that it can have a lower Higgs state.

• 39:24Neil deGrasse Tyson?

  It takes the whole rest of the universe with it.

• 39:26Matt O'Dowd?

  Yeah, and so the idea is you have this vacuum decay. That little part of the vacuum decays to that lower-energy state, and all of physics goes out the window. Everything loses mass, all particles can suddenly move at the speed of light. Time winks out as we understand it. We will become essentially photons.

• 39:42Eugene Mirman?

  Maybe say it.

• 39:44Neil deGrasse Tyson?

  Dogs and cats start dating one another?

• 39:46Eugene Mirman?

  If they don't turn into poles.

• 39:48Matt O'Dowd?

  That is highly hypothetical. No one has proven that.

• 39:51Eugene Mirman?

  Wait, so say it again. What happens?

• 39:53Matt O'Dowd?

  So the one thing the universe realizes that it is this new energy state and not what we thought, that bubble expands and at the speed of light envelops the universe.

• 40:01Eugene Mirman?

  Okay.

• 40:02Matt O'Dowd?

  But you know, the universe is big, so it might take a while.

• 40:04Eugene Mirman?

  So it depends where it starts.

• 40:05Matt O'Dowd?

  Yeah.

• 40:06Eugene Mirman?

  But if this is happening somewhere in the universe, then we'll just get swallowed up in it?

• 40:08Neil deGrasse Tyson?

  Yeah, basically.

• 40:09Eugene Mirman?

  So what are the chances it's already happening?

• 40:12Matt O'Dowd?

  The chance is we have no idea.

• 40:15Neil deGrasse Tyson?

  By the way, I think of this loss of the vacuum state every time I fly over Crater Lake. You know, it's the volcanic caldera and there's a crater there.

• 40:22Eugene Mirman?

  Sure.

• 40:23Neil deGrasse Tyson?

  And if there's a lake in it, there's water just sitting there.

• 40:25Eugene Mirman?

  Yeah, ready to kill you.

• 40:26Neil deGrasse Tyson?

  Now, if that water knew that it had access to the ocean below, it would go like that. But it doesn't know.

• 40:36Matt O'Dowd?

  Hmm, exactly.

• 40:37Neil deGrasse Tyson?

  It's trapped in this, in this, in this, it thinks it has reached the low ground because water always finds the lowest spot.

• 40:45Eugene Mirman?

  Mm-hmm.

• 40:46Neil deGrasse Tyson?

  Because water always finds the lowest spot. It thinks it has reached the low ground, but it doesn't know that it can get lower. And so I, like I said, I lose sleep wondering.

• 40:57Matt O'Dowd?

  And part of the problem is that because the new vacuum expands at the speed of light, we can't see it coming because light can't outpace it. The first indication we get would be it arriving.

• 41:08Neil deGrasse Tyson?

  It's too late.

• 41:09Eugene Mirman?

  So it sounds like there, in a sense, there's nothing to fear because it'll just happen.

• 41:14Matt O'Dowd?

  That's not gonna help me.

• 41:15Eugene Mirman?

  Well, meaning, I think a thing to fear is like...

• 41:18Neil deGrasse Tyson?

  You can't even watch it happen.

• 41:19Eugene Mirman?

  Yeah, it'll just be, well, have been a thing and then not a thing. That's not so bad.

• 41:22Neil deGrasse Tyson?

  Yeah.

• 41:23Matt O'Dowd?

  Yeah.

• 41:24Eugene Mirman?

  I mean, I don't prefer it.

• 41:26Matt O'Dowd?

  But we're a simulation anyway, so...

• 41:28Neil deGrasse Tyson?

  Exactly.

• 41:29Eugene Mirman?

  Yeah, but one that we really love being in.

• 41:32Neil deGrasse Tyson?

  Alright, what else you got?

• 41:33Eugene Mirman?

  Alright, um, let's...

• 41:35Neil deGrasse Tyson?

  Questions from the internet, yes?

• 41:37Eugene Mirman?

  Yes, um, let's read this question. Ready? D61636 on Instagram asks, "How was the Phoenix Cluster discovered and why hasn't it devoured our solar system?"

• 41:49Matt O'Dowd?

  I hope you know the answer to this.

• 41:51Neil deGrasse Tyson?

  No, I don't, I don't know what the Phoenix Cluster is.

• 41:53Eugene Mirman?

  Well, I guess that's another thing to fear.

• 41:58Neil deGrasse Tyson?

  Well, I don't, I don't know what the Phoenix Cluster is. You know what the Phoenix Cluster is?

• 42:02Matt O'Dowd?

  I know what the Phoenix Nebula is.

• 42:03Neil deGrasse Tyson?

  Oh, what is it?

• 42:04Matt O'Dowd?

  It's a rather beautiful star-forming nebula, um, that, I guess it's some hundreds of light-years away. It's, yeah, it's, it's quite pretty.

• 42:13Neil deGrasse Tyson?

  Let me back up for a minute. So, uh, I don't know if this answers that specific question, but it relates to it.

• 42:21Eugene Mirman?

  Sure.

• 42:22Neil deGrasse Tyson?

  If a black hole shows up somewhere, it doesn't automatically become some kind of huge vacuum sucking up everything that it didn't previously suck in before, given the mass that it once was. So, black holes are not giant sucking machines. If Earth, if Earth, if the Sun became a black hole, all the planets won't all of a sudden just get sucked into the Sun.

• 42:45Eugene Mirman?

  But we would be harmed.

• 42:46Neil deGrasse Tyson?

  Well, it would be cold.

• 42:48Eugene Mirman?

  It'd be very cold.

• 42:49Neil deGrasse Tyson?

  That's the only change.

• 42:50Eugene Mirman?

  Like, super cold.

• 42:51Neil deGrasse Tyson?

  Super cold.

• 42:52Matt O'Dowd?

  As cold as it gets.

• 42:52Neil deGrasse Tyson?

  As cold as is possible.

• 42:54Matt O'Dowd?

  So is this how we reassure people after the vacuum decay thing?

• 42:56Eugene Mirman?

  Now I get why people are afraid of science. The more you know, the more there is to fear.

• 43:01Neil deGrasse Tyson?

  So, if in this cluster there's some black hole they might have read about, I haven't gotten the latest on that, but if that's the case, you needn't fear freshly formed black holes. Because the gra, the gravity...

• 43:12Neil deGrasse Tyson?

  The reason why black holes are scary is because you can get very close to them. Because they're very small. And when you get close to them, you feel extraordinary gravitational effects on you. If you maintain the distance you've always had from that object, it makes no difference to you.

• 43:26Eugene Mirman?

  Like if a black hole was in Chicago, would we be fine here in New York?

• 43:29Matt O'Dowd?

  How big is the black hole?

• 43:30Neil deGrasse Tyson?

  It depends on how big the black hole is.

• 43:31Eugene Mirman?

  The size of a nice shoes.

• 43:33Matt O'Dowd?

  In, in, yeah.

• 43:35Neil deGrasse Tyson?

  Yeah, it would systematically eat the earth.

• 43:37Matt O'Dowd?

  Yeah, that would be, that would be like the massive Jupiter, I'm guessing.

• 43:40Neil deGrasse Tyson?

  Yeah, yeah, yeah.

• 43:41Eugene Mirman?

  So, uh, what if it was the size of a dime? So what if it was the size of a dime, would that destroy the earth?

• 43:46Matt O'Dowd?

  That would be the massive more than the earth.

• 43:48Neil deGrasse Tyson?

  No, no, earth is, earth is a black hole the size of like a grape.

• 43:51Matt O'Dowd?

  It's nine millimeters in diameter.

• 43:53Eugene Mirman?

  So a pomegranate seed, black hole, what would that do?

• 43:56Neil deGrasse Tyson?

  He's still coming with food.

• 43:58Matt O'Dowd?

  That sounds, that sounds rough too. The types of black hole that the Large Hadron Collider would produce in its, when it collides beams, those would be so infinitesimally small that it shouldn't be a problem. They should, they should decay instantly, for one thing.

• 44:12Eugene Mirman?

  Very reassuring. So the thing, so basically.

• 44:14Neil deGrasse Tyson?

  You should be okay.

• 44:15Eugene Mirman?

  Basically.

• 44:16Neil deGrasse Tyson?

  You'll probably be okay.

• 44:17Eugene Mirman?

  Time for another question.

• 44:18Neil deGrasse Tyson?

  Yeah, yeah, yeah, let's do it.

• 44:19Eugene Mirman?

  Right? When it comes to the multiverse theory, is there any way to know the ages of the various universes? Or would they all be the same age?

• 44:27Matt O'Dowd?

  Hmm, wow. So I think the answer is absolutely no way. Given that there's no way to, to test whether, uh, they exist.

• 44:37Neil deGrasse Tyson?

  So here's an interesting fact of science. Generally, if you don't know anything, your first question is the simplest. Does it exist?

• 44:46Eugene Mirman?

  Right.

• 44:46Neil deGrasse Tyson?

  Then when you confirm that it exists, then you ask the next round of questions. How long has it existed? Will it die? Then you go, how big is it? What are the properties? So, right now, we don't, we don't even know if multiverses exist.

• 45:00Eugene Mirman?

  Right.

• 45:00Neil deGrasse Tyson?

  Much less start handing out ages to them. The, the idea is, these things pop in and out of existence. Forever in some meta clock.

• 45:09Eugene Mirman?

  Right.

• 45:10Neil deGrasse Tyson?

  All right.

• 45:10Eugene Mirman?

  And yeah. So how would we, how would you know if there was another universe?

• 45:13Matt O'Dowd?

  Well, it also depends on the type of multiverse. I mean, there are many different types to choose from.

• 45:17Eugene Mirman?

  What's, what's, what's an example, like five examples?

• 45:20Matt O'Dowd?

  Five examples, easy, easy. Let me write. So there's the quantum multiverse, the idea of many worlds that, that, that the universe splits into, to multiple realizations of itself at every little subatomic decision.

• 45:31Eugene Mirman?

  Mm hmm.

• 45:33Matt O'Dowd?

  That one is the same, they're all the same age because they all started from the same branching chain. Then you have the.

• 45:40Neil deGrasse Tyson?

  This is the famous many worlds interpretation.

• 45:43Matt O'Dowd?

  So then you have the, the idea of the multiverse that, that expands from the, what I mentioned earlier in the, the show, the, the eternally inflating multiverse. So one part of it just stops inflating so crazily fast and just does regular big bang inflation. And those should, those should just be appearing all the time in that greater multiverse. One cool thing about those is that it may be possible to detect them if you happen to have two universes that kind of appeared like champagne bubbles and overlapped in the, in the very beginning.

• 46:15Neil deGrasse Tyson?

  Intersected.

• 46:15Matt O'Dowd?

  And, and merged. You would see like rings on the cosmic microwave background radiation, sort of coffee stains of where they interacted back in the beginning. And we haven't seen them yet, but we will keep looking.

• 46:28Eugene Mirman?

  Coffee stained universes. Somebody's a poet.

• 46:33Neil deGrasse Tyson?

  Oh, there's another one where the actual spacetime that you're in has pockets of non-causally connected expanding sections. So in other words, we look out to our horizon, but beyond that horizon, there's a whole other universe, but part of our spacetime, but we can't, we don't have access to it. And so that there's this huge fabric of spacetime and just universes dotting the space within it. And so.

• 46:59Matt O'Dowd?

  And that type should be as all, they all should be the same age.

• 47:01Neil deGrasse Tyson?

  Exactly.

• 47:02Matt O'Dowd?

  They started with the same big bang.

• 47:03Neil deGrasse Tyson?

  Exactly. That would be the same big bang that birthed it.

• 47:04Matt O'Dowd?

  That's three.

• 47:05Neil deGrasse Tyson?

  But my favorite one is the one where it's just this frothy foam that is birthing universes back and forth.

• 47:11Matt O'Dowd?

  And just for completeness, number five, the, the Fekkand universe of Lee Smolin, where black holes, when they form, they create new universes.

• 47:20Neil deGrasse Tyson?

  Because inside of a black hole, the mathematics tells you a whole other spacetime emerges. On the other side. After, because you fall in, you'll get to that after you see the future history of the universe from whence you came unfold.

• 47:33Eugene Mirman?

  No.

• 47:34Neil deGrasse Tyson?

  Yeah, so, yeah, that's... I got shivers just then.

• 47:36Eugene Mirman?

  Yeah, yeah. So the answer is, we don't know, but some of our ideas are really great.

• 47:42Neil deGrasse Tyson?

  We gotta stop it here. So you've been watching, if you've seen this on YouTube, or otherwise listening to StarTalk, a Cosmic Queries edition. I've been your host, Neil deGrasse Tyson, your personal astrophysicist. I think Eugene Mirman. Eugene, thanks for coming back.

• 47:57Eugene Mirman?

  Thank you very much for having me.

• 47:58Neil deGrasse Tyson?

  Call me sometime, Eugene.

• 47:59Eugene Mirman?

  I will.

• 47:59Neil deGrasse Tyson?

  All right, you're in Boston now.

• 48:00Eugene Mirman?

  I'm gonna start texting you science questions.

• 48:02Neil deGrasse Tyson?

  Okay, then I know you're alive. You're gonna say, "You up?"

• 48:08Eugene Mirman?

  I will. I'll be like, "How does the universe work, Neil? I'm at a bar with some friends, we wanna know."

• 48:13Neil deGrasse Tyson?

  Exactly, exactly. And I think my friend and colleague, Matt O'Dowd, who's got his own YouTube channel on PBS Digital Studios, and it's called... Spacetime. Spacetime. If I type in spacetime, it goes to you. Type it straight into... Doesn't go to Einstein's theory, it goes to you. We're number three, or something like that? Great having you. Thanks a lot. All right, good. So as always, I've been...