StarTalk Radio - Cosmic Queries – The Fractal Universe with Charles Liu

Episode Date: September 18, 2026

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.NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free.Thanks to our Patrons Mike Allen, Hailey Thorn, Daniel, Kyle Jones, Halloween Jack, Chris McDermott, AmberDawn, Jesabi Lornkapi, John Olsson, 🔭reality smacks!, Sam Paterson, Calder DeFord, Heerat Singh, Dylan Ledford, Xander Soren, Victoria S, Christoffer R Hansen, Montreaux Rodgers, Chris from VA, Scott Stroud, H, Prince, Samuel, Heidi Jim, Benjamin Ruso, Jason Sturgeon, Lonny Trestrail, Susan Levaque, Willy Croezen, Luke Stancs, Clare Bear, Alan Davis, Anthony Ware, Alejandro Pedraza, Monday Olives, Hal Garland, Ralts, Vaughan Hall, Cynthia, Darrel Wallace, Bryan Marks, Tsveta Bahchevanska, Steven Webber, North.T, Tyler O'Brien, Bob, Larry Prosser, Sean Mueller, LilBopper, Bender, n1ck_knack, Hisui Hyena, and Lou Taylor for supporting us this week. Subscribe to SiriusXM Podcasts+ to listen to new episodes of StarTalk Radio ad-free and a whole week early.Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus. Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

We had our geek and chief join us for StarTalk Special Edition, Cosmic Queries grab bag. Yeah. We went everywhere. Fractals in the universe, fractals in our brains. Yeah. And I made enemies on three continents. Again. Mm-hmm.

Coming up, StarTalk, special edition. Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk Special Edition, which of course means I got right beside me here, Gary O'Reilly. How you doing, Gary? I'm good, Neil. How's things? Very good. Very good. And, of course, Chuck Nice.

Chuck your baby. What's up? What's happening? So this is an uncommon installment of StarTalk Special Edition, where we are doing cosmic queries. like we do over in StarTalk flagship. We're going to do cosmic queries that are sort of focused a little bit on the themes of the show, but also it's going to reach out into the quantum realm. Oh, yeah. And who could best serve that in the world than our geek and chief, Charles Liu.

Hey, Charles. Hey, Neil. Hi, guys. What a pleasure to be here. Thank you for having me. The crowd cheers. Charles Lou, welcome back.

I'm just to remind people that you recently published a book, The Handy Quantum Question Book. Give me the full title of that. The Handy Quantum Physics Answer Book. Excellent. Yes. Very good. Yeah.

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 bring you on to a Cosmic Queries installment of, of special edition. So, Chuck Gary, you've got the questions? Yeah. Indeed.

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. Less than a cup of coffee per month. Less than a Starbucks cup of coffee. Yeah, where do you get your coffee, Chuck? Well, I drink very good coffee.

Oh. All right, so who's first up? This question from Marcus Rodzon, I believe that's how you pronounce it. If not, I apologize. Hey, Neeland 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? interstellar travel. Thanks and cheers from Switzerland. So this question is from a regular Einstein.

And just remind me, in fact, Iron Man's arc reactor, is that what's buried in his chest? Yes. Okay. Supposedly. Yeah. Yeah. Okay. He gets a ton of energy for free from a SIP physics basics. Yeah. Yeah. It's so unlikely. It's ridiculous. But it's, but it's cool because it's Iron Man. That's right. And it's the arc react 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. No, no, no. Hawkeye, the Black Widow, before she got her brain implant retcon and things like that.

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 Nan 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 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,

have some spacecraft that could have a nearly infinite or an arbitrarily large amount of energy, that spacecraft still cannot exceed the speed 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... Yeah, and, you know, the light from the sun is a little more than eight minutes. So that's not a... That's not going to hold us back. But you want to cross the galaxy that even at the speed of light, it's tens of thousands of years. And we don't live that long.

We don't live that long. No, now 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. As nomads.

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. Because if you have infinite energy sources, and even if you could travel with 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 and the, dark and all kinds of stuff everywhere. That travel time is a small fraction of the age of the galaxy. So you can easily do that within the time frames already known if you could do it. That's right. So the sun's been around for four and a half billion plus years. And so by then, there should be gazillions of civilization zipping around in their arc reactor-powered spaceships. And they're just not there yet. Do we dare to assume that other life forms haven't yet solved that problem about traveling at the speed of light? Well, this is a deep question that requires our understanding of their motivations, right?

Let's say a spacecraft can go to the speed of light. Say there's a 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. Or the three-body, the plot of the three-body problem series.

Correct. Just to be precise. Yeah. Yeah. Not the three-body problem. That's the physics problem. That's not solvable by analytic means. Right, right, right.

Or it can be something like the prime directive in the Star Trek world. Absolutely. 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. So just to summarize, to summarize what you're saying is, because 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 kind of evidence that they haven't, or like you said, they want to stay secret.

Those are two possible interpretations. 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. Be robotic, robotic exploration. 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. That makes sense. So if the space probes that have left our solar system, Voyager 1 and 2, 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? should we be seeing many of them? We haven't seen any. We've got a fifth probe escaping the solar system,

and that's the New Horizons mission that flew by Pluto. That's right. Because it continued on, right? Oh, yeah, yeah. Yeah, it just went past Pluto and kept going. With plenty enough speed to get its butt out of the solar system. 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? I mean, it's basically the speed of light is what it comes back to us. Back on Earth? It's hours. It's hours. Yeah, yeah. So, yeah, that's not bad at all. It's not days or weeks. Yeah, that's pretty, I got to say, that's pretty cool, man.

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. powerful or so huge that it sends its own signal all the way back. So it uses a relay system. Right.

Relay system, Gary. That's right. Very cool, man. Chuck you up. Here we go. This is Kenneth Cook. And Kenneth Cook says Dr. Tyson, Lord Nice, Dr. Lou 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 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. Oh, no. Ohio is a lovely place. Oh, please, Chuck. Stop trying to be so nice. I got family in Ohio. I got family in Ohio.

Okay. I visited Ohio for a conference about a year ago, enjoyed it so much as a wonderful little comic shop. Charles, we established on a previous episode that at the state border of every interstate, there's a picture of Chuck preventing him from entering. Absolutely. You got to understand. Chuck, you have to understand. Here's the thing. But you can't call Charles Liu Chuck if we're calling you Chuck. Charles, I would be happy to call you Charles.

You call you Chuck. We'll switch for a day. Yeah. The answer is, yes, there is a connection between the complexity in organization of the human brain and the complexity and organization of the universe. What? But that connection is mathematical and it's unclear because the math shows that the complexity is just a little bit different.

Here's how I think about it. And this has been my opinion ever since our friend and colleague Jan 11 sort of talked about this a bunch of years ago to a different question and a different show. The idea is that when things get complicated in nature and you've got to pack a lot of stuff into a little space, fractals start to develop. Fractal patterns are these things that sort of can self-repeat 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 a 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 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. So you're saying, let me just, because that was a lot, but I just want to.

I want to make sure I'm getting what you're saying here. Sure, absolutely. 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. Well said. Okay. That is a really, really good way to put it.

I was going to try to say something like that, but Chuck said it a little better. I want to 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. Wow. 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 arrived at is the same.

All right? Now, wait, suppose two of the children, one is named Mercury, another is named Jupiter. Then they're exactly the same. No. Now, if one's the kids were named Pluto, we would have a problem.

My nuance on what Charles said is the fact that fractals can be invoked to describe what we see is more the problem. praise of the potency of math, then it is the similarity of the two phenomena. 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. understand. One of Kenneth's points is about a simulation. Right. Now, if we have the similarity of fractal brain and a fractal universe for the moment's sake, that suggests a similar blueprint, and therefore this could then offer a thought towards the simulated reality. What a neat idea. Because you see, when we humans create our most sophisticated simulations, we also try to to mimic fractal patterns. Yeah. 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 a natural, possibly simulated construction that doesn't need a human being to make it? It's just the thing of the universe. Yeah, 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 spent about a half a year exploring fractals while I was in graduate school. It's a fun place to get lost in. Charles, just to tie up this sort of thought, does this fractural thinking offer a bridge between general relativity and the quantum?

Quantum mechanics, yeah. Quantum. Not yet. I know of people who are trying to use advanced mathematical ideas to try to put that together. Right now, the best bet we have is something between the general relativity and quantum mechanics. The bridge is something having to do with disorder rather than order. So in other words, entropy. 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. Wow. Order and disorder.

And vice versa. There you go. That's really cool, man. 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 4,000. 999 more in Lost in Space. 5,000 facts to help navigate the universe. Lost in Space is now available for pre-order wherever books are sold. All right. Next up, what do we have, Gary? Let's start. Is Martin LeBlanc? You're going to 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 50th state. At least not yet, Martin. I set them up, you knock them down. You just wait, Martin, you'll see. We're going to come across the Lake of America. 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 adjective here. Could the multiverse come from apophonia of the result of the math equations giving it a meaning that isn't really there? Did you say apophonia? Apophonia. What a great word.

It's the best. I've never heard that word. I've never heard that word. I'm pretty sure Apophonia sang with Prince, right? Apollonia. Apollonia 6. Oh, oh, oh, okay. Okay, apophonia.

Gary, I'm going to try to spell it, see if I remember. It's A-P-O-P-H-E-N-I-A, right? Correct, yes. Apophonia. 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. No, no, no.

That's called something else. That's called paradolia. That's called paradolia. That's called paradolia. Yes. Yes. But paradolia is a kind of way where we try to make patterns. All right.

So if you see a face on Mars or something. So apophonia, because apophonia is not just pictures, right? Parodolia is only visual. Apophonia 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 got to join me now because the chances are that I'm going to win again, that kind of thing. Says the person who never took statistics. Yeah.

But you see, we humans have that apophonic idea. Or here's another one. 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 you want to invest, wait until Kevin Bacon releases a movie and then you buy. So that's not paradox. That's a whole other effort to create patterns. patterns and order in the universe.

Correct. There's nothing to do with images. Paradolia specifically is about images. Apophilia. It's a subset of apophina. All kinds of different things. Cool. I learned something to that.

Yeah, isn't that cool? 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 you. they aren't there. All right. 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 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. But you kind of glossed over something there, Chuck, because you kind of just made an assumption that. we know what the wave function collapse is and the many world's theory.

I'm so sorry. You kind of just put all of that in one thing. I am thinking so, yeah, I'm so wrapped up having written the handy quantum physics answer book that sometimes I gloss over the detail. So thank you, Chuck, for pointing that out to me. 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. 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 into this many world's interpretation, which is the opposite of that, everything becomes concrete interpretation. That's called the Copenhagen. You mentioned the Copenhagen interpretation, right, Chuck. This multiverse. He said many worlds.

Right. 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.

Great call. I would add nuance to that, Chuck. Now I'm calling you Chuck, Charles, where if you think there's a pattern going on in nature, and there really isn't, but that's just 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 going to 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 do that if it's not in the equation to be had. That's all I'm trying to say. 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 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 apophina we're talking about. This is a random thing if you're rolling dice, for example. Okay, and they pick that. We're fine. Score seven three times in a row. I agree halfway with you with the basketball shots, but you can pick a, a piece of,

example of the apaphenia and stick it in my sentence and then that's how I would say it. I am cool with that. Yes. But 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 would have a certain number of successful shots in a row. All right. Do you have five occasions where you have three in a row?

Whatever. Okay. 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 going to 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 going to go statistically off what you expect from the shooting percentage they would have earned in the first place. 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. Probably because the defender is biting it today. 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. Do you mean that word again? What's it called? Apophonia.

Apophonia. So, we all know that we suffer from apophonia. I didn't know we had a word for it. I don't think math is susceptible to apophonia. I just want to put my concluding comment on that. Fair enough. And 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 apophonia, but rather the mathematical equations are sufficiently open-ended that it allows for the many-world's interpretation whether or not we humans are actually staring at the equations themselves. Nice. All right. Chuck, you're up next. Okay. This is Brian O'Brien. Really? Yes. Exactly. His initials of Bob. Oh, cool.

Oh, okay. 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? Hmm. Hmm. Okay. Let me first clarify. I believe

Brian O'Brien is asking about a wavelength shorter than Plunk's length, not Plunk's constant. Constant. Yeah, definitely sure. Because Plunk's constant

is a unit of angular momentum. And from Plank's constant, you can draw things like plunk length, a plunk time, a plunk mass. So since wavelength is what he's talking about, he's thinking about the plunk 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, 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. I got you. Right. The math of... It's not that something can't get smaller. is that all this stuff, nothing works past that.

Well said, yes. No, no, no, no, no, no. Go ahead, go ahead, go ahead. It means whatever happens past that, we have no freaking idea. No idea. Okay, all right. We're at the limits of our own theoretical understanding of how the universe works when you're inside the plank length. Right.

So there is nothing especially magical about the plonk 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 Plunk 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 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 plunk length. 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. I love that phrase. Neil, you used that in an article decades ago. No. Yeah, decades. It was decades ago. Yeah. 2009 was when that first showed up. The perimeter of our ignorance. 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 way? wavelength. But here's something. The frequency was so fast that the wavelength becomes small. Yeah, tiny, tiny. 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. Oh, okay. Look at that.

It can't. Right. Yeah. 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. That's right. That's right. The laws of physics that we use break down at limits like that, right? Yeah. Wow. It's very cool. Yeah.

So good thinking, Brian. Maybe you can help us figure it out. Hey, this is Kevin the Somelier, and I support StarTalk on Patreon. You're listening to StarTalk with Neil deGrasse Tyson. Gary, you're next up. All right. This question is from Prince. There you go.

Way. Who performed with Apophini as 6, right? Oh, yeah. 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.

Love it. May you never live closer to work so that you'll always have time to hear this show. 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 ceded life on planets across the universe to preserve and extend its civilization. Oh, it's a good movie. 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 Yon. The Next Generation, Season 6, Episode 20, The Chase. Did that answer your question?

Geekin-chief. Indeed it did, but it also created so many more. So Charles, we only grant you a quota for how many times in one StarTalk episode you can out geek me, okay? Sorry. And you're nearing your quota. Sorry. So you said that they came up with the reason why, Almost all aliens they encounter are humanoid.

That's right. Is this related? Are those common facts here? So to catch us up with that. 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 an tennie, some have blue skin, but, you know, what up with that? And so finally, the writers. Or ridges on the forehead, you know, whatever. Just little details, right? And the more messed up they look, that's when you know it's a black actor playing them. The more awesome they look. Okay. There you go.

But 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 Kardashians, 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 saying, yeah, billions of years ago, we seeded all of your planets because we wanted to have a legacy that extended beyond. our extinction. So I look like you. You look like me. Thanks guys. And that was it. 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. Right. Or Oracle or even God. Right. Or even God. 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. Right, right. And the fact they looked even as different as they did from one another is completely consistent with evolution creating variation. Yes. Once you have the basic plan of the head, arms, torso, and legs.

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 minutes. million years, it didn't require billions of years. Good point. 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.

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 in solidly. of the same groups of who we are, then we do between groups that we call different, proving that there can actually be no such thing as race. 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 process. file as a species.

Yeah. You have spoken genetically correctly. That's a genetically correct statement. It's just that true racists don't care about biology. You don't care what color your skin is. That's all. I can't say that. By the way, I do a joke about that.

And I say proving that God loves a race war because all the little differences that we share all show up on the outside for the most part. But yeah, that's a great line. It makes no difference because we. Racists don't care about biology. They don't learn science. That's a great line. You think they're applying to science?

Wait, wait, so do we answer the question, though, which was when the universe was smaller, galaxies were closer together. 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. That's right. 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.

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 interstellis 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. 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. So how old is our galaxy, the Milky Way guy? Our solar system is about 4.5 billion years old. How old is our galaxy? We think, based on the best evidence that we have, it's about 10 billion years old. Only 10.

Not even 12? You can give us only 10? 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. Cosmic Noon at the OK Corral. Yeah. Which galaxies?

One quick follow-ups based on that. So we see stellar nurseries. So stars are still being formed. Absolutely. Do we see galaxies still being formed? Yes. Oh. Yes.

I'm sorry. Oh, not at all. Charles, not really, Charles. Yes, really. Not in any big way. Define big. No, I got you. Do you want to define big? In any given I pick a thousand galaxies of random.

Okay. I would bet you 99.9.9.9 of those thousand galaxies were born 10 billion years ago. 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. What are galaxies? They're essentially large glomerations 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. 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 settled into a disc and swirled around and such. 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 galaxy 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. So to this day, galaxies are forming. However, okay, if that's how you're going to describe it, I'm with you. But those bits and pieces have been around since the

beginning of the universe. Not always. We think they probably have, but some of them may have, have been formed by the tidal tales of other galaxies that have collided and ripped them off from their original bodies. So, if they are forming from the collision of two other galaxies, it's detritus. That's what I'm saying. Where are you getting the whole, you know, where's the galaxy come from? At that point, what you're looking at is a garbage patch in the Pacific Ocean. That's really what you're looking at.

Some pieces of galaxies surely came from primordial histories, and other pieces of galaxies came from things that were cast off from other galaxies. That at one time we're primordial. That's what I'm saying. 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. God, that is, wow.

Isn't that awesome? Damn. Oh, wow. That was, that's some crazy, man. That's wild. Okay. I love it. That's cool, man.

All right. Thank you, Prince. And Prince. Prince. Look at that from beyond the grave. Still making Star Talk interesting. Let's go crazy. So, guys, we've got time for like two more questions if we're efficient in answering them. So who's up next?

All right. This is Rachel Cecil who says, hello, Dr. Tyson, Lou, and whatever comedic nobility is joining you. All right. You know what, Rachel, I'm going to skip your question now. No, no. I don't know. I don't know what the hell your problem is. Okay. Hey. Hey. Hey. No, here we go. She says, my name is Rachel Cecil, a high school astronomy teacher hailing from Chicago. I recently had a question. Teacher in the house. Teacher. 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'd check with my personal astrophysicist.

Oh. How do we know that the movie? of galaxies are caused by the expansion of space and not just their own movement through space itself. A superb question. The answer is the physics. You see, in order to push a galaxy at the speeds that we observe and 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. I got a better answer than that.

Oh, snap. What? Don't get competitive. Don't get competitiveness. Here we go. 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 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 the, themselves. That's what's amazing about it. This beehive of galaxies

has motion in and among themselves separate and distinct from their physical body motion of the cluster in the expanding universe. 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. But the whole cluster is susceptible to this. expansion of the universe. Are we good here, Charles? Yes. Yeah. So let me just, I'm trying to, I just want to make sure I get what you're saying, though. Yeah.

From that, would we infer that they're moving in a medium? The medium is space time. That's it. Is that the, correct. Yeah. They're embedded in the medium. And the medium is stretching. Right. Space time does not have to have density. Exactly. Okay. But the medium is space time.

It's space time itself. Oh, yeah. Well done. All right. Very nice. All right. There you go. Last question. Bring it out. All right. Here we go. Edward Tutin. Hello, Dr. Tyson, Chuck Nice, and Dr. Charles Liu, Eddie Tutan here from Florence, South Carolina. I've got a question that's been messing with my head.

Those are the best kind. 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.

Charles, let's answer simultaneously. Ready? Okay. Yes. So I'm going to 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. Just wrap your head around that. That's how far we've come. So now, and I want your backup on this, Charles, if you want to add to it. Sure.

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. You know what? You're absolutely right, and I'm totally okay with it. Well, I'm not. All right. I'm not okay with it. This is the thing, right? And Mr. Tutin, 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 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. Charles, you sound like a pastor who's saying, be grateful for what you have. 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't know and do know. This is awesome. Right? So I would not lose sleep over it, but rather I would go to sleep dreaming about all the awesomeness that exists because of it. Chuck, you are the most disgustingly optimistic person I have

ever met. 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 nodded a simulation once again? Oh, I do not think it needs to, but it could. It's not a prerequisite for it. It's not necessary, but it is sufficient. Yeah. Hey, listen, if I simulated a universe for you, idiots, I would definitely pull out the page.

Damn, Chuck. And I would thank you for it, Chuck. Thank you. Oh, man, we're just some little. aliens ant farm, aren't we, after all right. All right, right. All right, we got to land this plane. Oh, man. Charles Liu. I was checking you've got a whole other book coming out. Yes, I do. And October. Yes. And it is on superheroes? It is on supernatural science. What? Nice.

The real science of superheroes, mythic creatures, and the sci-fi universe. Whoa. When do I get one? Yeah. I believe it drops in October. The story is very simple. October 2026. October 2026.

So, Charles, that's going to sell a billion copies. Yeah, man, good for you. 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.

There you go. 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. Thank you. Thank you. All right. Well, Charles, always good to have you on here as our deacon chief.

Always happy to be here. Really appreciate it. Lord Nice. You know we love you. Always a pleasure. And Gary. Yes. Thanks for putting this together.

Yet another episode of StarCoff. No, no, you did not go to Lane Unsworth in our L.A. In our L.A. Lane is the best. on the case. All right. Neil deGrasse Tyson here, as always, is bidding you to keep looking up.