Cosmic Queries – The Fractal Universe with Charles Liu

Do the fractal nature of the universe and the human brain have anything to do with each other? Neil deGrasse Tyson and co-hosts Chuck Nice and Gary O’Reilly welcome back Geek-In-Chief Charles Liu, for a grab bag covering deep space travel, fractal mathematics, multiverse theory, and what we might never know about the universe.

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

• 0:00Neil deGrasse Tyson?

  We had our geek in chief join us for StarTalk Special Edition Cosmic Queries Grab Bag.

• 0:06Chuck Nice?

  Yeah.

• 0:07Neil deGrasse Tyson?

  We went everywhere. Fractals in the universe, fractals in our brains.

• 0:11Chuck Nice?

  Yeah, and I made enemies on three continents.

• 0:15Neil deGrasse Tyson?

  Again.

• 0:17Neil deGrasse Tyson?

  Coming up, StarTalk Special Edition.

• 0:21Neil deGrasse Tyson?

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

• 0:34Neil deGrasse Tyson?

  This is StarTalk Special Edition, which of course means I got right beside me here Gary O'Reilly. How you doing Gary?

• 0:41Gary O'Reilly?

  I'm good Neil. How's things?

• 0:43Neil deGrasse Tyson?

  Very good, very good. And of course Chuck Nice. What's up? What's happening? This is an uncommon installment of StarTalk Special Edition where we are doing Cosmic Queries like we do over in StarTalk flagship. We're gonna do Cosmic Queries that are so focused a little bit on the themes of the show, but also it's gonna reach out into the quantum realm. Oh yeah. And who's who could best serve that in the world than our geek in chief, Charles Lu. Hey, Charles.

• 1:21Charles Liu?

  Hey Neil. Hi guys. What a pleasure to be here. Thank you for having me.

• 1:28Neil deGrasse Tyson?

  The crowd cheers. Welcome back. I'm just gonna remind people that you recently published a book, The Handy Quantum Question Book. Give me the full title of that.

• 1:38Charles Liu?

  The Handy Quantum Physics Answer Book.

• 1:41Neil deGrasse Tyson?

  Excellent.

• 1:42Charles Liu?

  Yes.

• 1:42Neil deGrasse Tyson?

  Very good.

• 1:43Charles Liu?

  Yeah.

• 1:43Neil deGrasse Tyson?

  And because we all need handy answers to quantum questions. And given that this is the state of mind you've been in answering people's queries, we thought we'd bring you on to a Cosmic Queries installment of Special Edition.

• 1:59Charles Liu?

  Happy to do it.

• 2:00Neil deGrasse Tyson?

  Chuck, Gary, you've got the questions?

• 2:02Chuck Nice?

  Yeah. Indeed.

• 2:04Neil deGrasse Tyson?

  And they're asked by our Patreon supporters. The entry level gets you this, you don't even, just the entry level gets you the access.

• 2:13Chuck Nice?

  Less than a cup of coffee per month.

• 2:16Neil deGrasse Tyson?

  Less than a Starbucks cup of coffee.

• 2:18Charles Liu?

  Yeah. Where do you get your coffee Chuck?

• 2:21Chuck Nice?

  I drink very good coffee.

• 2:28Neil deGrasse Tyson?

  Alright, so who's first up?

• 2:29Gary O'Reilly?

  This question from Marcus Razon, I believe that's how you pronounce it. If not, I apologize. Hey Neil and team, when you look at the real bottlenecks of deep space travel from payload mass and transit times to life support and propulsion, is space exploration basically just a massive energy problem? If we had something with the insane energy density of Iron Man's arc reactor, how dramatically would that rewrite the rules of interstellar travel? Thanks and cheers from Switzerland. So this question is from a regular Einstein.

• 3:05Neil deGrasse Tyson?

  And just to remind me, Iron Man's arc reactor, is that what's buried in his chest?

• 3:09Chuck Nice?

  Yes.

• 3:10Neil deGrasse Tyson?

  Okay.

• 3:11Charles Liu?

  Supposedly. Yeah.

• 3:12Chuck Nice?

  Yeah.

• 3:13Neil deGrasse Tyson?

  Okay.

• 3:14Chuck Nice?

  He gets a ton of energy for free from a physics basics.

• 3:19Charles Liu?

  Yeah.

• 3:19Chuck Nice?

  Yeah. It's so unlikely, it's ridiculous, but, but it's, but it's, but it's cool because it's Iron Man.

• 3:25Charles Liu?

  That's right.

• 3:26Chuck Nice?

  And it's the arc reactor.

• 3:27Neil deGrasse Tyson?

  Right. And just to be clear Chuck, Iron Man is the least unbelievable Marvel character of them all. So to say, oh, that's ridiculous. If you're saying that about him, then none of the other characters mean anything to you.

• 3:44Charles Liu?

  I would, no, no, no Hawkeye, the Black Widow, before she got her brain implant, retcon and things like that. There, there's some pretty good superheroes without Iron Man's armor. But Iron Man's armor, yes, indeed, it evolved. Originally, it was designed to keep his heart going because it had been damaged. But then then became more and more and more powerful until now he's like godlike because he has this armor. But the interesting question, Marcus, is indeed, if you had essentially infinite energy, would we be able to zip around the stars with no problem? And the answer alas is no. And the reason is

• 4:21Neil deGrasse Tyson?

  Damn.

• 4:22Charles Liu?

  General theory of relativity. Okay. The special theory of relativity itself would suffice as well. In 1905, as you know, Albert Einstein, who was at that time doing his PhD work in Switzerland, had basically come up with an explanation that the faster you go, you can get more and more massive at the same time. And therefore, you will never reach the speed of light because you will reach infinite mass and it takes infinite energy in order to go there. So even if you could have some spacecraft that could have a nearly infinite or an arbitrarily large amount of energy, that spacecraft still cannot exceed the speed

• 5:02Charles Liu?

  of light. So it's still limited and we are all still limited in space travel by the amount of time light takes to get from one star to the next. Which is too bad, but.

• 5:13Neil deGrasse Tyson?

  Yeah. And you know, the light from the sun is, is a little more than eight minutes. So that's not a, that's not gonna hold us back. But you wanna cross the galaxy that's, even at the speed of light, it's tens of thousands of years.

• 5:25Charles Liu?

  Well, yeah, that's right.

• 5:26Neil deGrasse Tyson?

  And we don't live that long. We don't live that long.

• 5:28Charles Liu?

  No, no, that doesn't mean we shouldn't go. I mean, if people felt like it, you can go in things like generation ships. And that would be something that if you had infinite energy, then Marcus would be right. We could go across the galaxy.

• 5:42Chuck Nice?

  As nomads.

• 5:43Charles Liu?

  Right. But it would take us as a species, many, many, many generations. And in fact, this is one of the interesting points that often comes up when people talk about the Fermi paradox, right? Where are the aliens? If they are plentiful, why haven't we seen any of them? And the math is relatively simple. Cause if you have infinite energy sources, and even if you could travel at generation ships at say, close to the speed of light, in a few hundred thousand years, you should have versions of your intelligent species all over the Milky Way galaxy. We should be able to see tracks and planets that have lights in the dark and all kinds of stuff.

• 6:23Neil deGrasse Tyson?

  Cause that travel time is a small fraction of the age of the galaxy. So you can easily do that within the time, timeframes already known.

• 6:32Charles Liu?

  That's right.

• 6:32Neil deGrasse Tyson?

  If you could do it. Yeah.

• 6:34Charles Liu?

  That's right. So we, you know, the sun's been around for four and a half billion plus years. And so by then, there should be gazillions of civilizations zipping around in their arc reactor powered spaceships. And they're just not there yet.

• 6:47Gary O'Reilly?

  Do we dare to assume that other life forms haven't yet solved that problem about traveling at the speed of light?

• 6:54Charles Liu?

  Well, this is a deep question that requires our understanding of their motivations, right? Let's say a spacecraft can go the speed of light. So there's civilization that has developed this technology. And I absolutely, you know, Gary, your point is right on. I should not presume that there are no technologies or no civilizations that have developed such technology. But we don't see them. So does that mean that either they're doing it somewhere else? And we don't see them because we haven't looked? Or because they're actually hiding their tracks so that we don't see them because they don't want to be detected? Right? And that's something along the lines of either say the three body problem where you have to hide your existence from other species or they will come and destroy you.

• 7:38Neil deGrasse Tyson?

  Or the three body, the plot of the three body problem series.

• 7:41Charles Liu?

  Correct.

• 7:42Neil deGrasse Tyson?

  Just to be precise. Yeah.

• 7:43Charles Liu?

  Yeah. Not the three body problem, that's the physics problem.

• 7:45Chuck Nice?

  Right.

• 7:46Charles Liu?

  Not solvable by analytic means. Right, right, right. And, or it can be something like the prime directive in the Star Trek world.

• 7:53Chuck Nice?

  Absolutely.

• 7:53Charles Liu?

  Where we don't want to reveal ourselves because we don't want to interfere with other civilizations developing. So those are the questions that we have to wonder about. And since we've never had open known contact with other civilizations that have technology, we do not know what they're thinking.

• 8:15Neil deGrasse Tyson?

  So just to summarize, to summarize what you're saying is, cause Gary, you say, or which one of you said, maybe they could have come up with that, even if we don't know how to do that. Well, if they did, then we would see them. So that's kinda evidence that they haven't, or like you said, they wanna stay secret.

• 8:34Charles Liu?

  Those are two possible interpretations.

• 8:36Chuck Nice?

  The other, the other is that, which I think is far more likely, that a life form would not do the traveling itself. Because we've already done that. We now have a probe that has left our solar system.

• 8:54Neil deGrasse Tyson?

  Be robotic, robotic exploration.

• 8:55Chuck Nice?

  Right. And so most likely that would be our first encounter, or if they were able to see us, they would see us through the lens of a probe or something that they sent out before they themselves would ever, you know, take that endeavor.

• 9:15Charles Liu?

  That makes sense. So if the space probes that have left our solar system, you know, Voyager one and two, Pioneer 10, Pioneer 11, if they were ever to come within sensor detector range of another civilization, they could tell immediately that it's not your average asteroid or interstellar object that's flying through. They will see things and they should know that it's there. But if they're plentiful, where are they? You know, should we be seeing many of them? We haven't seen any.

• 9:46Neil deGrasse Tyson?

  We've got a fifth probe escaping the solar system and that's the New Horizons mission that flew by Pluto.

• 9:52Chuck Nice?

  That's right. Pluto. Cause it continued on, right?

• 9:56Neil deGrasse Tyson?

  Oh yeah. Yeah.

• 9:57Chuck Nice?

  Yeah. It just went past Pluto and kept going, keeps going.

• 9:59Neil deGrasse Tyson?

  Plenty enough speed to get, get its butt out of the solar system.

• 10:02Chuck Nice?

  Out of the solar system. That's wild, man. And how long does it take to receive the information that these probes might pick up? And I mean, it's basically the speed of light is what it comes back to us?

• 10:14Neil deGrasse Tyson?

  Yeah. Back on Earth. It's hours.

• 10:16Chuck Nice?

  It's hours. Okay.

• 10:17Neil deGrasse Tyson?

  Yeah. Yeah.

• 10:17Chuck Nice?

  So it's, yeah, that's, that's not bad at all.

• 10:23Neil deGrasse Tyson?

  It's not days or weeks, it's hours.

• 10:25Chuck Nice?

  Yeah, that's pretty, I gotta say, that's pretty cool, man.

• 10:28Charles Liu?

  Right. So you can imagine a daisy chain situation where you have lots of probes in lots of different spots, and they're transmitting different pieces of information across. They're all traveling at the speed of light, but no single probe has to be so powerful or so huge that it sends its own signal all the way back. All the way back, yeah.

• 10:45Gary O'Reilly?

  So it uses a relay system.

• 10:47Charles Liu?

  Right.

• 10:47Neil deGrasse Tyson?

  Yeah, relay system, Gary, that's right.

• 10:49Chuck Nice?

  Very cool, man.

• 10:50Neil deGrasse Tyson?

  Chuck, you up?

• 10:51Chuck Nice?

  Here we go. This is Kenneth Cook, and Kenneth Cook says, Dr. Tyson, Lord Nice, Dr. Liu, and Gary, the universe's cosmic web and the brain's neural networks seem to share themes of interconnectedness, information emergence, and immense complexity arising from simple rules. Since our brains are made by the universe, yet each brain constructs an entire experience reality, could these similarities reveal something fundamental, perhaps minds or smaller expressions of the universe's organizing structure, or even evidence consistent with simulated reality? Or are we merely projecting familiar patterns

• 11:34Chuck Nice?

  onto vastly different systems? What evidence could distinguish between those possibilities? Ken Cook writing from my own little slice of the universe in Dresden, Ohio. And to that, we say our condolences there, Ken.

• 11:48Charles Liu?

  Oh, no. Ohio's a lovely place.

• 11:51Chuck Nice?

  Oh, please, Chuck. Stop trying to be so nice. I've got family in Ohio. I've got family in Ohio, okay?

• 11:58Charles Liu?

  I visited Ohio for a conference about a year ago, enjoyed it so much. There's a wonderful little comic book shop right into them.

• 12:05Neil deGrasse Tyson?

  Charles, we established, we established on a previous episode, that at the state border of every interstate, there's a picture of Chuck preventing him from entering.

• 12:13Chuck Nice?

  Absolutely.

• 12:16Chuck Nice?

  You gotta, you gotta understand. Chuck, you have to understand. Here's the thing.

• 12:20Neil deGrasse Tyson?

  But you can't call Charles Liu Chuck if we're calling Chuck.

• 12:23Chuck Nice?

  Okay, all right.

• 12:24Charles Liu?

  Charles, I would be happy to call you Charles, and you call me Chuck. All right. Well, we'll switch for a day. Yeah. The answer is, yes, there is a connection between the complexity and organization of the human brain and the complexity and organization of the universe.

• 12:40Chuck Nice?

  What?

• 12:41Charles Liu?

  But that connection is mathematical, and it's unclear because the math shows that the complexity is just a little bit different. Here's, here's how I think about it, and it's just been my opinion ever since our friend and colleague, Jana Levin, sort of talked about this a bunch of years ago, to a different question, on a different show. The idea is that when things get complicated in nature, and you gotta pack a lot of stuff into a little space, fractals start to develop.

• 13:13Chuck Nice?

  Yeah.

• 13:14Charles Liu?

  Okay. Fractal patterns are these things that sort of can self-repeating and continue to create more and more complexity in smaller and smaller spaces. But there are different mathematical ways to express fractals. The most famous is something called the Mandelbrot set, but that's not the only one. So what's happened is that astronomers have measured the fractal-like patterns of the large-scale structure of the universe, galaxies, dark matter, things like that, and compared it to the fractal patterns of the human brain, and found that while they are both fractals, they are not the same fractals. They're not the same mathematical expressions. Therefore, it is fair to say that both the human brain's

• 13:54Charles Liu?

  complexity and its structure is related to the large-scale structure of the universe in that they are naturally created, and they are fractally based. But because the mathematics are different enough, we can also say conclusively that one and the other are not exactly the same. They are not linked in any kind of physical way, but they do have a mathematical commonality, which suggests that they're both arising from the same universal laws.

• 14:24Chuck Nice?

  So you're saying, let me just, because that was a lot, but I just wanna, I wanna make sure I, I'm getting what you're saying here.

• 14:32Charles Liu?

  Sure, absolutely.

• 14:33Chuck Nice?

  That there is an overarching physical property throughout the universe that propagates this type of, we'll call it, behavior. However, the behaviors are similar enough that this overarching property is at play, but they're dissimilar enough in that they're not directly connected so that our brains are little universes.

• 14:58Charles Liu?

  Well said.

• 14:59Chuck Nice?

  Okay.

• 14:59Charles Liu?

  That is a really, really good way to put it.

• 15:02Neil deGrasse Tyson?

  That's, I was gonna try to say something like that, but Chuck said it a little better. I, I wanna emphasize that because there's a mathematical similarity between two realms, it doesn't mean there's a physical similarity. It's just a statement of how potent mathematics is. It's why you can count eight planets in the solar system, and you can count eight children in a room. It doesn't mean the children are planets, even though the counting mechanism and the number you arrive at is the same. All right?

• 15:32Chuck Nice?

  Now, wait. Suppose two of the children, one is named Mercury, another is named Jupiter.

• 15:38Neil deGrasse Tyson?

  Then they're exactly the same.

• 15:43Charles Liu?

  Now, if one of the kids were named Pluto, now we would have a problem, now, wouldn't we?

• 15:48Neil deGrasse Tyson?

  My nuance on what Charles said is the fact that fractals can be invoked to describe what we see is more the praise of the potency of math than it is the similarity of the two phenomena.

• 16:06Charles Liu?

  Let me just qualify that by saying that the math was something that we humans saw in nature and put down on paper, right? So it's not a natural, you know, amazing thing that math is so awesome. It's that if math is indeed the language with which the universe has been written, then the math reflects something deep about the universe, which we do not yet understand.

• 16:30Gary O'Reilly?

  One of Kenneth's points is about a simulation.

• 16:33Charles Liu?

  Right.

• 16:34Gary O'Reilly?

  Now, if we have the similarity of fractal brain and a fractal universe, for heaven's sake, that suggests a similar blueprint, and therefore, this could then offer a thought towards the simulated reality.

• 16:50Charles Liu?

  What a neat idea. Because you see, when we humans create our most sophisticated simulations, we also try to mimic fractal patterns.

• 17:00Gary O'Reilly?

  Yeah.

• 17:01Charles Liu?

  Right? We, for example, have seen our cell phones get smaller and smaller, and the antennae in our cell phones no longer have to extend from our cell phones. And the reason is, in part, because there's a fractal pattern, the folding of that antenna has become kind of fractal, and we have done this with our own technology. So in the sense that we, being humans, being part of the universe, have decided that we want to use this fractal pattern to create our simulations, our machines, our computers, things like that, our networks, well, isn't that also an indication that whatever we're in has

• 17:43Charles Liu?

  a natural, possibly simulated, construction that doesn't need a human being to make it? It's just the thing of the universe.

• 17:53Neil deGrasse Tyson?

  Yeah, and, and fractals are pretty easy to simulate on a computer. So, they're even almost lazy. You can get a lot of structure for very trifling investment of your starter equations with a fractal code. So, but yeah, fractal, I love, I spent about a half a year exploring fractals while I was in graduate school. It's a fun place to get lost in.

• 18:16Gary O'Reilly?

  Charles, just to, just to tie up this sort of thought, does this fractal thinking offer a bridge between general relativity and the quantum?

• 18:24Charles Liu?

  Quantum mechanics, yeah. Quantum, not yet. I, I know of people who are trying to use advanced mathematical ideas to try to put that together, right? Right now, the best bet we have is something between the, the general relativity and quantum mechanics. The bridge is something having to do with disorder rather than order. So in other words, entropy. Thinking of entropy instead of just something you can't control, but as there are a series of disordered, say, steps in thermodynamics or in causality that have some sort of structure that, but the structure we don't understand yet. So maybe fractals are hiding in that, maybe they're not.

• 19:07Chuck Nice?

  Wow, order and disorder.

• 19:09Charles Liu?

  And vice versa. Amazing stuff, right?

• 19:11Chuck Nice?

  That's really cool, man.

• 19:23Neil deGrasse Tyson?

  Here's yet another fact from Lost in Space, the latest collaboration between StarTalk and National Geographic. One of Jupiter's moons, Europa, has an outer surface of frozen water, but beneath that, the water is rendered liquid by tidal stress from Jupiter and other surrounding moons. How much liquid water is there? More than twice the total water content of all of Earth's oceans. If you like that fact, you can find 4,999

• 20:06Neil deGrasse Tyson?

  more in Lost in Space. 5,000 facts to help navigate the universe. Lost in Space is now available for preorder wherever books are sold.

• 20:33Neil deGrasse Tyson?

  All right, next up, what do we have, Gary?

• 20:34Gary O'Reilly?

  Let's start with Martin LeBlanc. You're gonna guess where this is coming from. Bonjour, Dr. Tyson, Dr. Liu and Chuck. My name is Martin, reaching out from Montreal, Quebec, Canada. That's right, not the 51st state. At least not yet, Martin. I set him up, you knock him down. You just wait, Martin, you'll see.

• 20:55Gary O'Reilly?

  We're gonna come across the Lake of America.

• 21:02Gary O'Reilly?

  I always had trouble with the theory of multiverses. My brain can't make peace with the concept. I was listening to an explainer where Dr. Tyson mentioned that multiverses came out of math equations. He goes on to say, I'll play devil's advocate here. Could the multiverses come from apophenia of the result of the math equations giving it a meaning that isn't really there?

• 21:25Charles Liu?

  Did he say apophenia?

• 21:27Gary O'Reilly?

  Yes.

• 21:27Charles Liu?

  Apophenia, what a great word. It's the best.

• 21:31Gary O'Reilly?

  Explain, because I've never seen it before.

• 21:33Charles Liu?

  Okay.

• 21:34Chuck Nice?

  Wait, I'm pretty sure apophenia sang with Prince, right?

• 21:37Gary O'Reilly?

  Yeah.

• 21:39Charles Liu?

  Apollonia, Apollonia 6.

• 21:41Chuck Nice?

  Oh, oh, oh, oh, okay, all right.

• 21:44Charles Liu?

  Okay, apophenia. Gary, I'm gonna try to spell it, see if I remember. It's A.P.O.P.H.E.N.I.A., right?

• 21:52Gary O'Reilly?

  Correct, yes.

• 21:53Charles Liu?

  Apophenia. Okay, that is basically we humans trying to make patterns out of nothing. All right. We, for example, see a rock formation and say, oh, that's a face.

• 22:07Neil deGrasse Tyson?

  No, no, no, that's called something else.

• 22:10Charles Liu?

  That's called pareidolia. That's called pareidolia, okay?

• 22:13Neil deGrasse Tyson?

  Yes.

• 22:14Charles Liu?

  But pareidolia is a kind of way where we try to make patterns, all right? So if you see a face on Mars or something. So apophenia, because apophenia is not just pictures, right? Pareidolia is only visual. Apophenia is like, for example, okay, I have been playing craps for three hours and I won three times in a row. I'm on a hot streak. Everybody's gotta join me now because the chances are that I'm gonna win again. That kind of thing.

• 22:41Neil deGrasse Tyson?

  Says the person who never took statistics.

• 22:44Charles Liu?

  Yeah. But, but you see, we humans have that apophenic idea. Or, here's, here's another one. This, it's a more general thing. Like, imagine, okay, every time Kevin Bacon releases a new movie, the stock market goes up. So every time he buys a, every time you want to invest, wait till Kevin Bacon releases a movie and then you buy.

• 23:06Neil deGrasse Tyson?

  So that's not pareidolia. That's, that's a whole other effort to create patterns and order in the universe. There's nothing to do with images. Got it.

• 23:14Charles Liu?

  Pareidolia specifically is about images.

• 23:17Neil deGrasse Tyson?

  It's a subset of apophenia.

• 23:20Charles Liu?

  At all kinds of different things, right?

• 23:21Neil deGrasse Tyson?

  Cool. I learned something today.

• 23:23Charles Liu?

  Yeah, isn't that cool? So, so the idea here now is, yes, well, let's see. We are looking at the equations like a picture or like a bunch of patterns. And then we say, oh, you know what? I think that this mathematical equation implies that. Because you saw it there, because you see patterns where they aren't there. All right, that, that's a very interesting point. The answer, I think, Canadian, sir, meister, okay, is probably not. It is not apophenia. And the reason is the equations don't present that kind of pattern for you to make inferences from. What it does is it's open-ended. When you have a wave function

• 24:06Charles Liu?

  equation or with a bunch of dimensions and so forth, it just doesn't tell you that you have to get an answer that only exists by itself. And that's it. You can create a family of solutions which do not have a specific end point or an only this is the correct answer situation. That's why multiverse is mathematically acceptable.

• 24:32Chuck Nice?

  But you, you, you kinda glossed over something there, Chuck, because you kind of just made an assumption that we know what the wave function collapse is and, you know, the many worlds theory and...

• 24:46Charles Liu?

  Oops, you're right. I'm so sorry.

• 24:47Chuck Nice?

  You kinda just put all of that in one thing.

• 24:49Charles Liu?

  I, I am thinking so, yeah, I'm so wrapped up having written the handy quantum physics answer book that sometimes I gloss over the details. So thank you, Chuck, for pointing that out to me, right? Ordinarily, when we think of quantum physics, there is an uncertainty in the universe until we actually experience it or in the quantum speak, we measure it, right? The idea is that measurement, not necessarily with a ruler or with a yardstick or something like that, the measurement is an observation of something which then confirms the universe is like that, that thing that we saw. But before something is measured, we actually don't have a mathematical certainty that that's what it is. And so, the extension

• 25:34Charles Liu?

  into this many worlds interpretation, which is the opposite of that, everything becomes concrete interpretation, that's called the Copenhagen, you mentioned the Copenhagen interpretation, right, Chuck? The, this multiverse...

• 25:45Neil deGrasse Tyson?

  He said many worlds. He said many worlds.

• 25:47Charles Liu?

  Right, this many, this many worlds interpretation suggests that if I measure it and I get this universe, what if somebody else measures it and gets this other universe? All of a sudden, you have two different universes. And then somebody else does it, or that I measure it in a different time stream, or that I have no real constraints on how the thing is measured and who measures it and where it gets measured. So with that, that's the freedom that the mathematical equations currently allow. And therefore, many worlds is mathematically acceptable, not because we've seen a pattern in it that may or may not exist, but because the equations themselves are open-ended, shall we say.

• 26:27Neil deGrasse Tyson?

  Well, I would, I would, I would add nuance to that, Chuck. Now I'm calling you Chuck, Charles, where, where, if you think there's a pattern going on in nature, and there really isn't, but that's just our, our, our brain bias installing it that way, the universe has no such brain bias. Our math doesn't have a brain bias. Nature is the ultimate judge, jury and executioner, not your absence of knowledge of statistical math, right? So, we're not gonna look at equations and come up with some pattern, because our brain likes patterns, just because we have the power to do so. The equation won't let you

• 27:09Neil deGrasse Tyson?

  do that if it's not in the equation to be had. That's all I'm trying to say.

• 27:14Charles Liu?

  You make a good point. We talk about basketball players having a hot hand, right? They've made three shots in a row. Quick, give him the ball so he'll shoot more. That's not exactly what we're talking about here, because basketball shooting is not a random process, right? It's not a thing that happens randomly. Sometimes someone does have a hot hand because of the combination of their training and their brains and the game situation is such that they are locked in to take a shot. That's not the apophenia we're talking about. That's, this is a random thing. If you're rolling dice, for example.

• 27:44Neil deGrasse Tyson?

  Okay, then pick that, we're fine.

• 27:46Charles Liu?

  Score seven three times in a row.

• 27:47Neil deGrasse Tyson?

  I, I agree halfway with you with the basketball shots. But you can pick a, a pure example of the apophenia and stick it in my sentence, and then that's how I would say it.

• 27:58Charles Liu?

  I, I'm cool with that. Yes.

• 27:59Neil deGrasse Tyson?

  But what, what they have done, what they have done is, let's say my shooting percentage is 35% from the field in basketball, right? A 35% shooting percentage, depending on how many shots you took, will tell you how many occasions you'd have a certain number of successful shots in a row. All right? Do you have five occasions where you had three in a row? Whatever. Okay, now, now you're playing in a game and that game, you're shooting 50%, okay? So, you have a hotter hand in that game than you did in the previous game. And so, you will have longer sequences of where you'll make the shot. But I'm gonna

• 28:41Neil deGrasse Tyson?

  assert that at the end of the day, what is your shooting percentage, that your shots in a row that you made will be consistent with that shooting percentage. It's not gonna go statistically off what you expect from the shooting percentage they would have earned in the first place. It, so, but to your point, it is possible for someone to have a really good game, at which point they're drawing from a higher shooting percentage than other games they've played. In which case, their whole game, they have a hot hand.

• 29:11Charles Liu?

  Probably because the defender's biting it today.

• 29:16Neil deGrasse Tyson?

  Yeah, so just to summarize, the urge to think there's a pattern unfolding is, and thanks for that new word, Chuck and our fellow from Montreal.

• 29:27Neil deGrasse Tyson?

  Give me that word again, what's it called?

• 29:28Chuck Nice?

  Apophenia.

• 29:30Neil deGrasse Tyson?

  Apophenia. So with that, we all know that we suffer from apophenia. I didn't know we had a word for it. The, the, I don't think math is susceptible to apophenia. That just want to put my concluding comment on that.

• 29:45Charles Liu?

  Fair enough. And the, the way that the multiverse works, right? We interpret the equations of quantum physics, not in our human sort of limitation that we're susceptible to apophenia, but rather the mathematical equations are sufficiently open-ended that it allows for the many worlds interpretation, whether or not we humans are actually staring at the equations themselves.

• 30:10Chuck Nice?

  Nice. All right.

• 30:13Neil deGrasse Tyson?

  Chuck, you're up next.

• 30:14Chuck Nice?

  Okay, this is Brian O'Brien.

• 30:19Neil deGrasse Tyson?

  Really?

• 30:19Chuck Nice?

  Yes.

• 30:20Neil deGrasse Tyson?

  Really?

• 30:21Chuck Nice?

  Exactly.

• 30:22Gary O'Reilly?

  His initials are Bob.

• 30:24Chuck Nice?

  Oh, cool.

• 30:25Neil deGrasse Tyson?

  Oh, okay.

• 30:26Chuck Nice?

  And you shall now be known as Bob, sir. There you go. What happens when spin frequencies are so fast that the wavelength produced would be shorter than Planck's constant? Does causality reverse?

• 30:47Charles Liu?

  Hmm.

• 30:48Neil deGrasse Tyson?

  Hmm.

• 30:51Charles Liu?

  Um, okay. Let me first clarify. I believe Brian O'Brien is asking about a wavelength shorter than Planck's length, not Planck's constant.

• 31:06Chuck Nice?

  Constant.

• 31:07Neil deGrasse Tyson?

  Yeah, definitely, sure.

• 31:08Charles Liu?

  Because Planck's constant is a unit of angular momentum. And from Planck's constant, you can draw things like Planck length, a Planck time, a Planck mass. So since wavelength is what he's talking about, he's thinking about the Planck length, which is, as the name suggests, figured out by a guy named Max Planck, all right, about 120-ish years ago. And this length is about 10 to the minus 35 meters. Okay, so many, many, many, many,

• 31:48Charles Liu?

  many times smaller than the diameter of a proton. And it is conceived of as sort of the physical limit beyond which things like quantum mechanics and general relativity don't work. Okay?

• 32:06Chuck Nice?

  I got you.

• 32:07Charles Liu?

  Right. The math of...

• 32:09Chuck Nice?

  It's not, it's not that something can't get smaller. It's just that all this stuff, nothing works past that.

• 32:15Charles Liu?

  Well said. Yes.

• 32:16Neil deGrasse Tyson?

  No, no, no, no, no. More precise. No, no, no, no.

• 32:18Chuck Nice?

  Go ahead, go ahead, go ahead.

• 32:20Neil deGrasse Tyson?

  Whatever happens past that, we have no frickin' idea.

• 32:23Chuck Nice?

  No idea. Okay, all right.

• 32:25Neil deGrasse Tyson?

  We're at the limits of our own theoretical understanding of how the universe works when you're inside the Planck length.

• 32:33Charles Liu?

  Right. So there is nothing especially magical about the Planck length itself, except that our theoretical physics structure doesn't explain what happens before it. Okay. So a lot of what people are trying to do to figure out the origins of the universe, the Big Bang and so forth, is talking about that era. It's often called the Planck time or the Planck era, when the universe itself had a diameter of smaller than that Planck length, that there's a lot of really creative mathematical and physical thought processes going on to try to explain it, because our existing quantum mechanics and general relativity do not apply

• 33:13Charles Liu?

  very well, and those smaller sizes. So in that case, Brian O'Brien, I love saying Brian O'Brien. I mean, what a guy. Okay. I would say that, Brian, that you would not necessarily have time go backwards. But we don't know. It is a boundary of our knowledge of physics, of what would happen if something went smaller, if the wavelength became reduced compared to, say, the Planck length.

• 33:39Neil deGrasse Tyson?

  I prefer to call it a horizon beyond which we don't know. Boundary, sounds like it is a boundary, but it's really a horizon of our knowledge, a perimeter of our ignorance.

• 33:49Charles Liu?

  I love that phrase. Neil, you used that in an article decades ago. No.

• 33:55Neil deGrasse Tyson?

  Yeah, decades. It was decades ago. Yeah.

• 33:57Charles Liu?

  2009 was when that first showed up.

• 33:59Chuck Nice?

  The perimeter of our ignorance.

• 34:01Neil deGrasse Tyson?

  Perimeter of our ignorance. But let me add a nuance to this. Okay. He was just talking about the frequency of something being faster than, or was it a wavelength?

• 34:12Charles Liu?

  Yeah, the frequency was so fast that the wavelength become small. Yeah, tiny, tiny.

• 34:17Neil deGrasse Tyson?

  Right, right. So, but there are other interesting limits. For example, how fast can a pulsar spin? Okay. And there's a limit. There's a limit. It can't spin faster than its equator moving at the speed of light.

• 34:34Chuck Nice?

  Oh, look at that!

• 34:36Neil deGrasse Tyson?

  It can't.

• 34:38Chuck Nice?

  Right, yeah.

• 34:39Neil deGrasse Tyson?

  Okay, so other stuff, exotic general relativistic things begin to happen so that that never happens. And so, but I don't think that, I thought initially that's what it was getting at, but it's another interesting limitation brought upon us by deep laws of physics, preventing you from entering a realm that you'd otherwise think, let's just go there. But no, you can't.

• 35:02Charles Liu?

  That's right. The laws of physics that we use break down at limits like that. Right?

• 35:08Neil deGrasse Tyson?

  Yeah.

• 35:09Chuck Nice?

  Wow.

• 35:09Charles Liu?

  It's very cool. Yeah. So good thinking, Brian. Maybe you can help us figure it out.

• 35:28Charles Liu?

  Hey, this is Kevin the Sommelier, and I support StarTalk on Patreon. You're listening to StarTalk with Neil deGrasse Tyson.

• 35:42Neil deGrasse Tyson?

  Gary, you're next up.

• 35:44Gary O'Reilly?

  All right. This question is from Prince.

• 35:47Charles Liu?

  No way.

• 35:49Gary O'Reilly?

  Way.

• 35:50Charles Liu?

  Who performed with Apophenia 6, right?

• 35:52Gary O'Reilly?

  Oh, yes. Just get your purple on. Okay. Hello, Dr. Tyson and Supreme Overlord Nice, new Patreon member and huge fan of the show for educating me every day a little bit more on my daily commute to work. You're welcome. I'm so glad you enjoy what we do.

• 36:08Neil deGrasse Tyson?

  May you never live closer to work so that you'll always have time to hear this show.

• 36:16Gary O'Reilly?

  Oh, that's wonderful. My question is this. Considering what we know about the history and expansion of the universe, when galaxies were much closer together, and I love this question, is it possible that intelligent civilization and intelligent civilization once became capable of interstellar travel and anticipating the universe's continued expansion deliberately seeded life on planets across the universe to preserve and extend its civilization?

• 36:46Chuck Nice?

  Oh, it's a good movie.

• 36:48Neil deGrasse Tyson?

  Charles, I want to slip this in. You said long ago, and I didn't know, because I didn't follow Star Trek into Next Generation and beyond.

• 36:55Charles Liu?

  The Next Generation, season six, episode 20, The Chase. Did that answer your question?

• 37:05Neil deGrasse Tyson?

  Geek in chief.

• 37:06Chuck Nice?

  Indeed it did, but it also created so many more.

• 37:12Neil deGrasse Tyson?

  So Charles, we only grant you a quota for how many times in one, in one StarTalk episode, you can out geek me. Okay?

• 37:20Charles Liu?

  Sorry.

• 37:21Neil deGrasse Tyson?

  And you're nearing your quota.

• 37:22Charles Liu?

  Sorry.

• 37:25Neil deGrasse Tyson?

  So you'd said that they came up with the reason why almost all aliens they encounter are humanoid.

• 37:30Charles Liu?

  That's right.

• 37:31Neil deGrasse Tyson?

  Is this related? Are those common facts here? So catch us up with that.

• 37:35Charles Liu?

  Sure. The classic problem with Star Trek is that all the aliens, well, with very few exceptions, have one head, two arms, two legs, and a torso. Right? Why do we all look so similar? You know, some have antennae, some have blue skin, but you know, what, what up with that? And so finally, the writers...

• 37:54Neil deGrasse Tyson?

  Or ridges on the forehead.

• 37:56Charles Liu?

  Just little details, right?

• 37:58Chuck Nice?

  And the more messed, the more messed up they look, that's when you know it's a black actor playing them.

• 38:06Charles Liu?

  The more awesome they look.

• 38:08Chuck Nice?

  Okay, there you go.

• 38:11Charles Liu?

  The story really does come down to this episode was the writer's homage to that idea. Why do we all look so similar? And the idea was that there were four races, the Cardassians, the Romulans, the Klingons, and the humans, that found some archaeological evidence that there was some really secret, amazing information on some planet somewhere. And so they were all racing, chasing this information to get to that information. And the information turned out not to be a super weapon, not to be some incredible technological advance, but it was just a little video message that's saying, yeah, billions of years ago, we seeded all of your planets because we wanted to have a legacy

• 38:56Charles Liu?

  that extended beyond our extinction. So I look like you, you look like me. Thanks, guys.

• 39:02Chuck Nice?

  And that was it. And they, but they thought it was going to be like it's incredible weapon that they would be able to use to give them supremacy over the entire galaxy.

• 39:13Neil deGrasse Tyson?

  Right. Or Oracle, or even God.

• 39:15Chuck Nice?

  Right.

• 39:17Charles Liu?

  Right. And so that was it. And so some of the representatives from the different races were like, that's it? Come on, what a waste. But then there was another deeper conversation saying, wow, so we're related after all, huh? Perhaps, you know, we could talk about that.

• 39:32Neil deGrasse Tyson?

  And the fact they looked even as different as they did from one another is completely consistent with evolution creating variation.

• 39:41Charles Liu?

  Yes.

• 39:42Neil deGrasse Tyson?

  Once you have the basic plan of the head, arms, torso, and legs.

• 39:47Charles Liu?

  Right. But let me just say that as cool as the storyline is and that this idea is, it's not necessary. Right? If you think about it, evolution doesn't need billions of years to create incredible diversity. Right? So for example, monkeys, which do have two arms and two legs, but they also have a prehensile tail. They, and we, as humans, evolved together until, what, 10, 20 million years ago, something like that? So separation was within only a few million years. It didn't require billions of years.

• 40:27Neil deGrasse Tyson?

  Good boy.

• 40:28Charles Liu?

  If you go back 100 million years ago, we don't even need to be mammals, right? We are descended from the same common ancestors as the dinosaurs. And then millions of years later, as mammals developed, we had the same common ancestors, whales. And then beyond that, then things like chimps and monkeys and things like that from there. So the seeding is actually not necessary. All that had to happen was that we would wind up in an environment where evolution by natural selection can go on, and we can have all the variety and all the commonality that we would like.

• 41:04Chuck Nice?

  Yeah, but I will say that in addition to what you just said, because that was beautiful, I think there is a deeper meaning that they were trying to show humanity, which has been borne out biologically, is that we have more variation inside of the same groups of who we are than we do between groups that we call different, proving that there can actually be no such thing as race.

• 41:39Chuck Nice?

  And so the unity of Homo sapiens is so tight that the cosmetic differences that we share are meaningless when you look at our DNA profile as a species.

• 41:56Charles Liu?

  Yeah. You have spoken genetically correctly.

• 41:59Neil deGrasse Tyson?

  That's a genetically correct statement. It's just that true racists don't care about biology. They don't care what color your skin is. That's all.

• 42:06Chuck Nice?

  I can't tell you that. By the way, I do a joke about that, and I say, proving that God loves a race war.

• 42:14Chuck Nice?

  Because all the little differences that we share all show up on the outside, for the most, for the most part. But yeah, that's a great, that's a great line. It makes no difference because racists don't care about biology.

• 42:28Neil deGrasse Tyson?

  They don't learn science.

• 42:30Chuck Nice?

  That's a great line.

• 42:31Neil deGrasse Tyson?

  They're applying science. Wait, wait, Charles, so do we answer the question, though? Which was when the universe was smaller, galaxies were closer together. My, my mild rebuttal to that was, when the galaxies were significantly closer together, the universe was much, much younger, and there might not have been time to have created all the heavy elements to make the planets, to make the life that would then evolve.

• 42:56Charles Liu?

  That's right.

• 42:56Neil deGrasse Tyson?

  And then go from galaxy to galaxy. So you're up against a different time constraint if you want interesting things to happen in the early universe.

• 43:05Charles Liu?

  Well, there's a size constraint as well, yes. And that's a great point, Neil, and we should address that point. The entire Star Trek story all happened within one small portion of one galaxy, the Milky Way. Okay, so if we're talking about an interstellar species, that's within a single galaxy. An intergalactic species seeding stuff is even less likely, although there is certainly the possibility that four and a half billion years, assuming that a galaxy forms right near the beginning of the universe's history, would be enough, and that would still give nine or so billion years for the universe to expand even larger.

• 43:45Charles Liu?

  At that point, you would wind up having a further distance to travel in co-moving coordinates. But at the same time, that's already way beyond what the technology of, say, Star Trek stories is already referring to.

• 44:00Chuck Nice?

  So how old is our galaxy, the Milky Way? Where, where, our solar system is about four and a half billion years old. How old is our galaxy?

• 44:07Charles Liu?

  We think, based on the best evidence that we have, it's about 10 billion years old.

• 44:13Neil deGrasse Tyson?

  Not even 12? You're gonna give us only 10?

• 44:15Charles Liu?

  We think we were formed around what we call cosmic noon. All right? Which is when most of the galaxies we see, the universe currently, are likely to have formed, which was about 10 billion years ago, plus or minus, like I said, one to two billion years.

• 44:30Neil deGrasse Tyson?

  Cosmic noon at the O.K. Corral.

• 44:35Chuck Nice?

  And one quick follow-up, based on that. So we see stellar nurseries, so stars are still being formed.

• 44:42Charles Liu?

  Absolutely.

• 44:43Chuck Nice?

  Do we see galaxies still being formed?

• 44:45Charles Liu?

  Yes.

• 44:46Chuck Nice?

  Oh!

• 44:47Charles Liu?

  Yes.

• 44:47Chuck Nice?

  I'm sorry.

• 44:51Neil deGrasse Tyson?

  Charles, not really, Charles.

• 44:53Charles Liu?

  Yes, really.

• 44:54Neil deGrasse Tyson?

  Not in any big way.

• 44:56Charles Liu?

  Define big.

• 44:57Neil deGrasse Tyson?

  No, I got you. Do you want to define big? In any given night, pick 1,000 galaxies at random.

• 45:03Charles Liu?

  Okay.

• 45:04Neil deGrasse Tyson?

  I would bet you 999.9 of those 1,000 galaxies were born 10 billion years ago.

• 45:12Charles Liu?

  You might be close to that answer, but you have built in a selection bias. You're choosing the galaxies in the sky right now. Right? What are galaxies? They're essentially large agglomerations of matter that we are familiar with, things like stars, planets, interstellar gas, and things like that, bound together gravitationally by an even larger blob of dark matter. Okay? So for a long time, we thought that because galaxies were only things that we sort of saw out there, just as Neil is describing right now, they had to form a single way, the way that our Milky Way galaxy formed, that a lot of stuff came together and it kind of condensed and it, you know, settled into a disk and swirled around and such.

• 45:55Charles Liu?

  We now understand that there are pieces of galaxies still coming together as we speak today, things that we wouldn't recognize looking out there as galaxies unless we looked very, very carefully. These things might only have a few hundred, a few thousand, a few million stars, but they've got the dark matter, they've got the material, and they are slowly but surely converging into a single thing which billions of years from now, we would recognize as something resembling the Milky Way galaxy.

• 46:25Chuck Nice?

  Damn.

• 46:26Charles Liu?

  So to this day, galaxies are forming.

• 46:29Neil deGrasse Tyson?

  However, okay. If that's how you're going to describe it, I'm with you.

• 46:33Charles Liu?

  There you go.

• 46:33Neil deGrasse Tyson?

  But those bits and pieces have been around since the beginning of the universe.

• 46:36Charles Liu?

  Not always. We think they probably have, but some of them may have been formed by the tidal tails of other galaxies that have collided and ripped them off from their original bodies.

• 46:53Chuck Nice?

  If they are forming from the collision of two other galaxies.

• 47:00Neil deGrasse Tyson?

  It's detritus.

• 47:01Chuck Nice?

  It's that's what I'm saying. How, where, where are you getting the whole, you know, where's the galaxy come from? What, what you, at that point, what you're looking at is a garbage patch in the, in the Pacific Ocean. That's really what you're looking at.

• 47:17Charles Liu?

  Some, some pieces of galaxies surely came from primordial histories and other pieces of galaxies came from things that were cast off from other galaxies.

• 47:29Neil deGrasse Tyson?

  That at one time were primordial. That's all I'm saying.

• 47:32Charles Liu?

  This is the same as us being formed as stars, right? We're formed of material that was ejected from other stars as they died, combined with hydrogen atoms that have been traveling through the universe since the beginning of the universe. So it's a mixture of old and new, stars, galaxies, all of it.

• 47:53Chuck Nice?

  God, that is, wow.

• 47:56Charles Liu?

  Isn't that awesome?

• 47:56Chuck Nice?

  Damn. Oh, wow. That was, that's some, that's some crazy, man. That's wild. Okay.

• 48:03Charles Liu?

  I love it.

• 48:03Chuck Nice?

  That's cool, man. All right.

• 48:06Neil deGrasse Tyson?

  Thank you, Prince.

• 48:07Chuck Nice?

  Hey, Prince. Look at that. From beyond the grave, still making, making star talk interesting.

• 48:14Charles Liu?

  Let's go crazy.

• 48:17Neil deGrasse Tyson?

  So guys, we've got time for like two more questions if we're efficient in answering them. So who's up next?

• 48:22Chuck Nice?

  All right. This is Rachel Cecil, who says, hello, Dr. Tyson, Liu, and whatever comedic nobility is joining you.

• 48:33Chuck Nice?

  All right. You know what, Rachel? I'm gonna skip your question now.

• 48:37Chuck Nice?

  I don't know. I don't know what the hell your problem is. Okay.

• 48:44Chuck Nice?

  No, here we go. She says, my name is Rachel Cecil, a high school astronomy teacher hailing from Chicago. I recently had a question.

• 48:51Neil deGrasse Tyson?

  Teacher in the house.

• 48:52Chuck Nice?

  Teacher. We love you. I recently had a question from a student that stumped me. I told them I'd get back to them after I checked with my personal astrophysicist. How do we know that the movement of galaxies are caused by the expansion of space and not just their own movement through space itself?

• 49:12Charles Liu?

  A superb question. The answer is the physics. You see, in order to push a galaxy at the speeds that we observe them to be moving, it would require an enormous amount of force. Rockets, energy, the stuff that is moving that much stuff out there, requires a propulsion, a thrust, that there is no way any physical system could ever produce. So we can only conclude that the reason that they're moving and away from us and so fast is because they are embedded in something that's growing and the galaxies are just along for the ride.

• 49:57Neil deGrasse Tyson?

  I got a better answer than that.

• 49:58Chuck Nice?

  Oh, snap.

• 50:01Chuck Nice?

  What?

• 50:04Charles Liu?

  Here we go.

• 50:05Neil deGrasse Tyson?

  So watch this. You ready? So Hubble in 1920, late 1920s, he discovers what was then interpreted as the expanding universe, because all these galaxies had speeds headed away from us. Okay. And a galaxy twice as far away was receding twice as fast. Three times as far away, three times as fast. This is the signature of some kind of an explosion. That's what explosions look like if you're in the middle of it and you're looking out. And so that forced people to think something's going on here. So now let's fast forward to

• 50:45Neil deGrasse Tyson?

  modern times. There are galaxy clusters out there. If you look at all the galaxies in the cluster and measure their speeds, they're all moving away from us. All of them. And on top of that motion, they have movement among themselves. That's what's amazing about it. This beehive of galaxies has motion in and among themselves, separate and distinct from the physical body motion of the cluster in the expanding universe. And because we can distinguish those two kinds of speeds, we can say comfortably that galaxies do move through space while they're orbiting their center of their mass of their galaxy cluster.

• 51:28Neil deGrasse Tyson?

  But the whole cluster is susceptible to this expansion of the universe. Are we good here, Charles?

• 51:35Charles Liu?

  Yes.

• 51:35Chuck Nice?

  Yeah. So let me just, I'm trying to, I just want to make sure I get what you're saying, though.

• 51:40Neil deGrasse Tyson?

  Yeah.

• 51:40Chuck Nice?

  From that, would we infer that they're moving in a medium?

• 51:45Charles Liu?

  The medium is spacetime.

• 51:46Chuck Nice?

  That's, is that the?

• 51:47Neil deGrasse Tyson?

  Correct.

• 51:48Charles Liu?

  Yeah.

• 51:48Neil deGrasse Tyson?

  They're embedded.

• 51:49Chuck Nice?

  They're embedded in the medium.

• 51:51Neil deGrasse Tyson?

  And the medium is stretching.

• 51:53Charles Liu?

  Right. Spacetime does not have to have density. It doesn't have to have material, but the medium is spacetime.

• 51:59Chuck Nice?

  It's spacetime itself.

• 52:00Neil deGrasse Tyson?

  Oh, yeah.

• 52:01Charles Liu?

  Which, well done.

• 52:02Chuck Nice?

  All right.

• 52:02Charles Liu?

  Very nice.

• 52:03Chuck Nice?

  All right.

• 52:03Neil deGrasse Tyson?

  There you go. Last question. Bring it up.

• 52:05Gary O'Reilly?

  All right. Here we go. Edward 210. Hello, Dr. Tyson, Chuck Nice, and Dr. Charles Liu. Eddie Tooten here from Florence, South Carolina. I've got a question that's been messing with my head.

• 52:18Neil deGrasse Tyson?

  Those are the best kind.

• 52:21Gary O'Reilly?

  Not always. If dark energy continues accelerating, the expansion of the universe until distant galaxies disappear beyond our cosmic horizon, could a civilization in the far future eventually have no observable, observable evidence that those galaxies, or even the big bang, as we understand it, ever existed? If so, could a scientifically advanced civilization develop a completely wrong picture of the universe simply because it was born too late? I'd love to hear all three of your thoughts on this. Thanks and keep looking up.

• 52:56Neil deGrasse Tyson?

  Charles, let's answer simultaneously. Ready?

• 52:58Charles Liu?

  Okay.

• 52:59Neil deGrasse Tyson?

  Yes.

• 52:59Charles Liu?

  Yes.

• 53:02Neil deGrasse Tyson?

  So I'm gonna come in the back door of that, because I lose sleep over this. So just to be clear, if all the galaxies received beyond our horizon, there is no information about the origin of the universe. Everything we would know and love about what we think of the universe is just the stars in our backyard comprising the Milky Way. It would be like before Hubble discovered that there were other galaxies. When Einstein came up with relativity, the universe was the stars in the night sky. All right. That, just wrap your head around that. That's how far we've come. So now, and I, and I want your backup on this, Charles, if you want to add to it.

• 53:36Charles Liu?

  Sure.

• 53:37Neil deGrasse Tyson?

  So I lose sleep wondering, is there some chapter of the book of the universe that has been removed that we don't even know was there, simply because of when we were born into this universe? And here we are touching parts of the elephant, not seeing the elephant for itself. Is there some piece of the universe, which if it were still attached, it would be obvious what dark matter and dark energy were. But here we are in the dark, basking in our ignorance. Charles, take it from there.

• 54:19Charles Liu?

  You know what? You're absolutely right, and I'm totally okay with it.

• 54:25Neil deGrasse Tyson?

  Well, I'm not. I'm not okay with it.

• 54:27Charles Liu?

  This is the thing, right? And, and Mr. Tooten, this is exactly the philosophical context that we all live in. You are absolutely right, and Neil is absolutely right. It is almost certain that folks in that kind of a universe could not learn fundamental cosmologies as we do now. And it's almost certain that there are parts of the universe or histories of the universe that we do not know and we don't have contact with, and therefore we are in ignorance. But so what? That's okay. We will someday learn those things if we can. And if we can't, there are still all kinds of amazing things left to learn. Even though all other galaxies would recede away in your scenario, we would still have the

• 55:11Charles Liu?

  Milky Way. We would still have hundreds of billions of stars, hundreds of billions of planets, amazing things happening, evolution by natural selection, billions of years of changing history, of all kinds of amazing things to discover. Nothing would prevent us from enjoying that universe that we could access while we were there.

• 55:34Neil deGrasse Tyson?

  Charles, you sound like, you sound like a pastor who's saying, be grateful for what you have.

• 55:39Charles Liu?

  Well, I mean, I don't want to be too Panglossian, but I do want to say that it is healthy for us to wonder, what do we not know or what can we never know? While at the same time going, hey, check out the stuff that we can know and do know. This is awesome, right? So I would, I would not lose sleep over it, but rather I would go to sleep dreaming about all the awesomeness that exists because of it.

• 56:06Chuck Nice?

  Chuck, you are the most disgustingly optimistic person I have ever, ever met.

• 56:12Gary O'Reilly?

  No, I celebrate, I celebrate Charles positivity. I think that's just a brilliant way to look at that. And to Neil's point, if there's a chapter or slash page missing from the universe's storybook, does that then sort of nodder the simulation once again?

• 56:29Charles Liu?

  Oh, I do not think it needs to, but it could.

• 56:34Neil deGrasse Tyson?

  It's not a prerequisite for it.

• 56:35Charles Liu?

  Yeah. It's not necessary, but it is sufficient.

• 56:38Chuck Nice?

  Yeah. Hey, listen, if I simulated a universe for you idiots, I would definitely pull out the page.

• 56:47Neil deGrasse Tyson?

  Damn, Chuck.

• 56:49Charles Liu?

  And I would thank you for it, Chuck. Thank you.

• 56:53Gary O'Reilly?

  Oh, man. We're just some little aliens ant farm, aren't we?

• 56:58Neil deGrasse Tyson?

  All right. We gotta land this plane.

• 57:00Chuck Nice?

  Oh, man.

• 57:00Neil deGrasse Tyson?

  Charles Liu, Charles, you've, you, I was checking, you've got a whole other book coming out.

• 57:07Charles Liu?

  Yes.

• 57:08Neil deGrasse Tyson?

  And October.

• 57:10Charles Liu?

  Yes.

• 57:10Neil deGrasse Tyson?

  And it is on superheroes?

• 57:13Charles Liu?

  It is on supernatural science.

• 57:16Chuck Nice?

  What?

• 57:17Gary O'Reilly?

  Nice.

• 57:19Charles Liu?

  The real science of superheroes, mythic creatures, and the sci-fi universe.

• 57:25Chuck Nice?

  Whoa.

• 57:26Gary O'Reilly?

  When do I get one?

• 57:27Chuck Nice?

  Yeah.

• 57:28Charles Liu?

  I believe it drops in October.

• 57:32Charles Liu?

  The story is very simple.

• 57:33Neil deGrasse Tyson?

  October 2026.

• 57:34Charles Liu?

  October 2026.

• 57:35Neil deGrasse Tyson?

  So, Charles, that's gonna sell a billion copies.

• 57:38Chuck Nice?

  Yeah, man. Good for you.

• 57:39Charles Liu?

  I hope so. Thank you. I love science fiction. I love stories of the supernatural and superheroes. And I just want people to like revel in the coolness of the combination of human imagination and what the real universe has to offer. It's just great stuff.

• 57:55Chuck Nice?

  Very cool. Hey, if you want to give me a couple cases, I'll put them in the trunk of my car and make pretend I'm bootlegging them at Comic Con for you.

• 58:02Charles Liu?

  Thank you. Thank you.

• 58:05Neil deGrasse Tyson?

  All right. Well, Charles, always good to have you on here as our geek in chief.

• 58:08Charles Liu?

  Always happy to be here. Really appreciate it.

• 58:10Neil deGrasse Tyson?

  Lord Nice, you know we love you.

• 58:12Chuck Nice?

  Always a pleasure.

• 58:13Neil deGrasse Tyson?

  And Gary.

• 58:15Gary O'Reilly?

  Yes.

• 58:16Neil deGrasse Tyson?

  Thanks for putting this together. Yet another episode.

• 58:19Gary O'Reilly?

  The nod goes to Lane Unsworth in our LA office.

• 58:22Neil deGrasse Tyson?

  In our LA office.

• 58:23Chuck Nice?

  Lane is the best.

• 58:24Neil deGrasse Tyson?

  On the case. All right. Neil deGrasse Tyson here, as always, bidding you to keep looking up.