Lex Fridman PodcastKonstantin Batygin: Planet 9 and the Edge of Our Solar System | Lex Fridman Podcast #201
EVERY SPOKEN WORD
150 min read · 30,092 words- 0:00 – 1:18
Introduction
- LFLex Fridman
The following is a conversation with Konstantin Batygin, planetary astrophysicist at Caltech, interested in, among other things, the search for the distant but mysterious Planet Nine in the outer regions of our solar system. A quick mention of our sponsors: Squarespace, Literati, Onnit, and NI. Check them out in the description to support this podcast. As a side note, let me say that our little sun is orbited by not just a few planets in the planetary region, but trillions of objects in the Kuiper Belt and the Oort Cloud that extends over three light years out. This, to me, is amazing, since Proxima Centauri, the closer star to our sun, is only 4.2 light years away. And all of it is mostly covered in darkness. When I get a chance to go out swimming in the ocean far from the shore, I'm sometimes overcome by the terrifying and the exciting feeling of not knowing what's there in the deep darkness. That's how I feel about the edge of our solar system. One day, I hope humans will travel there, or at the very least, AI systems that carry the flame of human consciousness. This is the Lex Fridman podcast and here's my conversation with Konstantin Batygin.
- 1:18 – 16:16
Overview of our Solar System
- LFLex Fridman
What is Planet Nine?
- KBKonstantin Batygin
Planet Nine is an object that we believe lives in the solar system beyond the orbit of Neptune. It orbits the sun with a period of about 10,000 years and, uh, is about five Earth masses.
- LFLex Fridman
So that's a hypothesized object.
- KBKonstantin Batygin
That's right.
- LFLex Fridman
There's some evidence, uh, for this kind of object. There's a bunch of different explanations. Can you give, like, an overview of the planets in our solar system, how many are there, what do we know and not know about them at a high level?
- KBKonstantin Batygin
All right. That sounds like a good plan. So look, the solar system basically is comprised of two parts, the inner and the outer solar system. The inner solar system has the planets Mercury, Venus, Earth, and Mars. Now, Mercury is about 40% of the orbital separation of- where the Earth is, is closer to the sun, Venus is about 70%. Uh, then Mars is about 160% o- further away from the sun than is the Earth. These planets that we, uh, one of them we occupy, right, are pretty small, okay? They're, to leading order, sort of heavily overgrown asteroids, if you will.
- LFLex Fridman
(laughs) Okay.
- KBKonstantin Batygin
Um, and this is- this becomes evident when you move out further in the solar system and encounter Jupiter, which is 316 Earth masses, right, ten times the size. Um, you know, and Saturn is another huge one, 90 Earth masses, at about ten times, uh, the separation from, uh, the sun as is the earth. And then you have Uranus and Neptune at 20 and 30 respectively. For a long time, that is where the kind of massive part of the solar system ended. But what we've learned in the last 30 years is that beyond Neptune, there is this expansive field of icy debris, a second icy asteroid belt, uh, in the solar system. A lot of people have heard of the asteroid belt which lives be- between Mars and Jupiter, right? Like, that's a pretty common thing that people like to imagine and draw on lunchboxes and stuff.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
But beyond Neptune, there's a much more massive and much more radially, uh, expansive, uh, field of debris. Pluto, by the way, it belongs to that second, you know, icy asteroid belt which we call the Kuiper Belt. It's just a big object within that population of bodies.
- LFLex Fridman
Oh, Pluto the planet?
- KBKonstantin Batygin
Pluto, the- the dwarf planet, the former planet, you know?
- LFLex Fridman
Why is Pluto not a planet anymore?
- KBKonstantin Batygin
I mean, it's tiny. We used to-
- LFLex Fridman
So size matters when it comes to planets?
- KBKonstantin Batygin
Oh, 100%. 100%.
- LFLex Fridman
All right.
- KBKonstantin Batygin
It's, uh, actually a fascinating story. When Pluto was discovered in 1930, the th- the reason it was discovered in the first place is because astronomers at the time were looking for a seven Earth mass planet somewhere beyond Neptune, okay? It was hypothesized that such an object exists. When they found something, they interpreted that as a seven Earth mass planet, and immediately revised its mass downward because they couldn't resolve the object with the telescope. So it looked like a, just a point mass, you know, star-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... rather than a physical disk. And they said, "Well, maybe it's not seven, maybe it's one," right? And then, sort of over the next, um, you know, I guess 40 years, Pluto's mass kept getting revised down, down- downwards, downwards, downwards, until, uh, it was realized that it's, like, 500 times less massive than the earth.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Right? I mean, like, Pluto's surface area is almost perfectly equal to the surface area of Russia-
- LFLex Fridman
Hm.
- KBKonstantin Batygin
... actually. And, you know, Russia is big but it's not a planet.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Uh, well, I mean, actually, we can, we can touch more on that-
- LFLex Fridman
That's-
- KBKonstantin Batygin
... in a little bit ...
- LFLex Fridman
... that's another discussion. Uh, so in, in some sense, early in the century, Pluto represented kind of our ignorance about the edges of the solar system, and perhaps Planet Nine is the thing that represents our ignorance about now, the modern set of ignorances about the edges of our solar system.
- KBKonstantin Batygin
That's a good way to put it.
- 16:16 – 21:11
What is the Oort Cloud?
- LFLex Fridman
Okay. You mentioned the Kuiper Belt. What's the Oort cloud? If you look at the Neptune orbit as, uh, one, then the Kuiper Belt's like 1.3 out there.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
And then we get farther and farther into the darkness.
- KBKonstantin Batygin
Sure.
- LFLex Fridman
What, what's the Oort cloud?
- KBKonstantin Batygin
So, okay, you've got the kind of main co- Kuiper Belt which is about say 1.3, 1.5. Um, then you have something called the scattered disc, which is kind of an extension of the Kuiper Belt. It's a bunch of these long, uh, very elliptical orbits that hug the orbit of Neptune but come out very far. So that, the scattered disc, um, with the current census, like the, some of the longest, uh, orbits we know of, um, have a semi-major axis, so half the orbit length roughly speaking of about 1,000, 1,000 times the distance between the Earth and the sun.
- LFLex Fridman
Wow.
- KBKonstantin Batygin
Now, if you keep moving out, okay, eventually once you're at sort of, you know, 10,000 to 100,000 roughly, that's where the Oort cloud is. Now the Oort cloud is a distinct population of icy bodies and it's distinct from the Kuiper Belt. It's, in fact, it's so expansive that it ends roughly halfway between us and the next star. Um, its, its edge is just dictated by w- to what extent does the solar gravity reach.
- LFLex Fridman
Solar gravity reaches that far?
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
So it has to... Wow.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
So, in fact the-
- LFLex Fridman
Imagining this is a little bit overwhelming. So there's-
- KBKonstantin Batygin
It can, it can be.
- LFLex Fridman
... like a giant, like vast, icy rock thingy.
- KBKonstantin Batygin
It's like a sphere. It's like, you know, it's like a s- almost spherical structure that engulfs, that encircles the sun, and all the long period comets come from the Oort cloud. They come... The way that they appear, I mean, for already, I don't know, hundreds of years we've been detecting occasionally like a comet will come in and-... it come, seemingly comes out of nowhere.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
The reason these long-period comets appear, they've very- on very, very long time scales, right? These Oort cloud objects that are sitting, you know, 30,000 times as far away from the sun as is the Earth, actually interact with the gravity of the galaxy, the tide, uh, effectively the tide that the galaxy exerts upon them, and their orbits slowly change and they elongate-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... to the point where once they, their closest approach to the sun starts to reach a critical distance where ice starts to sublimate, then we discover them as comets because then the ice comes off of them.
- LFLex Fridman
Wow.
- KBKonstantin Batygin
They look beautiful in the night sky, et cetera. But they're all coming from-
- LFLex Fridman
They're-
- KBKonstantin Batygin
... you know, really, really far away.
- LFLex Fridman
So, uh, is there, are any of them coming our way from collisions? Like how many collisions are there? Or is there a bunch of space for them to move around?
- KBKonstantin Batygin
Yeah, there's zero. Like, they, it's completely collisionless. Out there, the physical radii of objects are so small compared to the distance between them, right, it's just, it is truly a collisionless, uh, environment. I don't know, the, I think that probably in the age of the solar system, there have literally been zero collisions in the Oort cloud.
- LFLex Fridman
Wow. When you like draw a picture of the solar system, everything's really close together so that everything I guess here is f- spaced far apart. Do rogue planets like fly in every once in a while and join? Not rogue planets but rogue objects from out there?
- KBKonstantin Batygin
Oh, sure. Oh, sure.
- 21:11 – 22:44
Life in the interstellar medium
- KBKonstantin Batygin
thing.
- LFLex Fridman
Let me ask you about the, the millions of objects that are part of the Kuiper Belt and the part of the Oort cloud. Do you think some of them have primitive life? Because it kind of makes me sad (laughs) if there's like primitive life there and they're just kind of like lonely out there in space.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
Like how many of them do you think have life, like bacterial life?
- KBKonstantin Batygin
Probably a negligible amount. Zero, you know, like zero with like a plus on top.
- LFLex Fridman
Right.
- KBKonstantin Batygin
Uh, right? So-
- LFLex Fridman
Zero plus plus.
- KBKonstantin Batygin
Yeah. (laughs)
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Um, if, so, you know, if you and I took a little trip to the interstellar medium, I think we would develop cancer and die, uh, real fast, right?
- LFLex Fridman
That's rough, huh?
- KBKonstantin Batygin
Yeah, it's, uh, pretty hostile radiation environment. Um, you don't actually have to go to the interstellar medium, you just have to leave the Earth's magnetic field to, um, and then you're not doing so well suddenly.
- LFLex Fridman
(laughs) Yeah.
- KBKonstantin Batygin
So, you know, this, this idea of, you know, life kind of traveling between places, it's not, it's not entirely implausible, but you, you really have to twist I think a lot of parameters. One of the problems we have is we don't actually know how life originates, right? So, it's kind of a second order question of, of survival in the interstellar medium and, and how resilient it is because we, we think you require water, but, and that's certainly the case for the Earth-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... but, you know, we, uh, we really don't know for sure. That said,
- 22:44 – 25:23
Are there aliens out there?
- KBKonstantin Batygin
I will argue that the question of like are there aliens out there is a very boring question.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Because the answer is of course there are.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Right? I mean, like, we know that there are planets around almost every star.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Um, of course there, of course there are other life form... Life is not some specific thing that happened on the Earth and that's it, right? Just, that's a statistical impossibility.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Um...
- LFLex Fridman
Yeah, but the, the difficult question is before even the fact that we don't know how life or- originates, I don't think we even know what life is, like definitionally.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
Like formalizing a kind of picture of, in terms of the mechanism we would use to, to search for life out there, or even when we're on a planet to say, "Is this life?" (laughs) "Is this rock that just moved from where it was yesterday life?" (laughs) Or, or maybe not even a rock-
- KBKonstantin Batygin
Life's-
- LFLex Fridman
... something else.
- KBKonstantin Batygin
... I gotta tell you, I wanna know what life is.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Okay? And I want you to show me.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Uh... (laughs)
- LFLex Fridman
(laughs) I think there's a song to basically accompany every single (laughs) thing-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... we talk about today, and, and probably s- uh, half of them are love songs. Um, and somehow we'll integrate George Michael into the whole thing. Okay. So your intuition is l- there's life everywhere in our universe. Do you think there's intelligent life out there?
- KBKonstantin Batygin
I think it's entirely plausible. I mean, uh, it's entirely plausible, um, you know, I think, I think there's intelligent life on Earth. Um, and-
- LFLex Fridman
So yeah, taking that, like say whatever this thing we got on Earth, whether it's dolphins or humans, say that's intelligent.
- KBKonstantin Batygin
Uh, definitely dolphins. I mean-
- LFLex Fridman
Yes.
- KBKonstantin Batygin
... have you seen the dolphins?
- LFLex Fridman
Well, they do some cruel stuff to each other. So, if cruelty (laughs) -
- KBKonstantin Batygin
(laughs)
- LFLex Fridman
... is a, is a definition of intelligence, th- they're pretty good.
- 25:23 – 28:04
How unique is Earth?
- LFLex Fridman
is if we have intelligent life here on Earth, if you take dolphins, pigs, humans, from the perspective of, like, planetary science-
- KBKonstantin Batygin
Mm.
- LFLex Fridman
... how unique is Earth?
- KBKonstantin Batygin
Okay, so Earth is not a com- common outcome of the planet formation process. Um, it's probably a, something on the order of maybe a 1% effect. And by Earth, I mean, not just-
- LFLex Fridman
Small.
- KBKonstantin Batygin
... an Earth-mass planet.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Okay? I mean the architecture of the solar system that allows the Earth to exist in, in its kind of very temperate, um, way. One thing to understand, uh, and this is, this is pretty crucial, uh, right, is that the Earth itself formed well after the gas disk that formed the giant planets, um, well, had already dissipated. You see, stars start out with, you know, the star and then a disk of gas and dust that encircles it, okay? From this disk of gas and dust, big planets can emerge.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
And we have over the last, uh, you know, two, three decades discovered thousands of extra-solar planets-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... planet in orbit around other stars. What we see is that, uh, many of them are, you know, have these expansive hydrogen-helium atmospheres. The fact that the Earth, uh, doesn't is deeply connected to the fact that Earth took about 100 million years to form. So, we missed that, you know, train, so to speak, to get that hydrogen-helium atmosphere. That's why actually we can see the sky, right? That's why the sky is, uh, well, at least in most places, that's why the, the atmosphere is not completely opaque. Um, with that, you know, kinda thinking in mind, I, I would argue that we're getting the kinda emergent pictures that the Earth is, is not, you know, everywhere, right? We, there's sort of the sci-fi view of things where we go to some other star and we just land on random planets and they're all Earth-like. That's totally not true. But the, even a low probability event, even if you imagine that Earth is a one in a million, or one in a, you know, one in 10 million occurrence, there are 10^12 stars in the galaxy.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Right? So you just, you always win by-
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
... by-
- LFLex Fridman
Large numbers.
- KBKonstantin Batygin
That's right, by supply.
- LFLex Fridman
They save you.
- 28:04 – 34:18
Did Jupiter destroy early planets?
- LFLex Fridman
Well, you've, uh, hypothesized that there, our solar system once possessed a population of short-period planets that were destroyed by the evil Jupiter-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... uh, migrating through, uh, the s- the solar nebula. Can you explain?
- KBKonstantin Batygin
If I was to say what was the k- kind of the key outcome of searches for extra-solar planets, it is that most stars are encircled by short-period planets that are, um, you know, a few Earth masses, right? So, a few times bigger than the Earth, um, and have orbital periods that kind of range from days to, to weeks, okay?
- LFLex Fridman
Oh, wow.
- KBKonstantin Batygin
Now, if you go a- and ask the solar system, "What's in our region," right, in that region, it's completely empty, right? It's just, it's astonishingly hollow. And think, you know, from ... The sun is not some, you know, special star that decided that it was going to form the, the solar system. So I think, you know, the natural thing to assume is t- is that the same processes of planet formation that occurred everywhere else also occurred in the solar system. Following this logic, it's not implausible to imagine that the solar system once possessed a system of intra-Mercurian, like, you know, compact system of, of planets. So then, we asked ourselves, "Would such a system survive to this day?" And the answer is no. Uh, at least our calculations, uh, suggest that it's highly unlikely because of the formation of Jupiter. And Jupiter's primordial kind of wandering through the solar system would have sent this collisional field of debris that would've pushed that system of planets onto the sun.
- LFLex Fridman
So was Jupiter, with its primordial wandering, w- what did, what did Jupiter look like? Like, why was it wandering?
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
It, it didn't have the orbit it has today?
- KBKonstantin Batygin
Uh, we're pretty certain that giant planets like Jupiter, when they form, they migrate. The reason they migrate is, um, you know, on a detailed level, perhaps difficult to explain, but you know, just in a qualitative sense, uh, they form in this fluid disk of gas and dust.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
So it's kind of like thinking if I plop down a raft somewhere in the ocean, will it stay in the, where you plop it down, or will it kind of get carried around? It's not really a good analogy because it's not like Jupiter's being advected by the currents of, you know, gas and dust, but the way it...... it migrates is it carves out a hole in the, in the disk and then, uh, through, by interacting with the disk gravitationally, right, it can change its orbit. The fact that-
- LFLex Fridman
I'm interested.
- KBKonstantin Batygin
... the solar system has both Jupiter and Saturn here complicates things a lot, right? Because it's, you have to solve the problem of the evolution of the gas disk, the evolution of Jupiter's orbit in the gas disk, plus evolution of Saturn's, and their mutual interaction. The common outcome of solving that problem, though, is pretty easy to explain. Jupiter forms, its orbit shrinks, and then once Saturn forms, its orbit catches up, basically, to the orbit of Jupiter and they both come out.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
So there's this inward-outward pattern of Jupiter's, uh, early motion that happens sort of within the fir- within the last million years of the lifetime of the solar system's primordial disk. So Ju- while this is happening, if our calculations are correct, uh, which I think they are, you can destroy these in- this inner system of, you know, few Earth-mass planets.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
And then, in the aftermath of all this violence, you form the terrestrial planets, right?
- LFLex Fridman
Wh- where would they come from in that case? So y- so Jupiter clears out the space.
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
And then there's a g- a few terrestrial planets that come in, and th- those come in from the, from the disk somewhere? Like one of the-
- KBKonstantin Batygin
So they-
- LFLex Fridman
... larger objects?
- KBKonstantin Batygin
Yeah. They w- what actually happens in these calculations is you leave behind a rather mass-depleted-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... like, remnant, uh, remnant disk.
- LFLex Fridman
Gotcha.
- KBKonstantin Batygin
Only a couple Earth masses.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
So, um-
- 34:18 – 38:50
How hard is it to simulate the Universe?
- KBKonstantin Batygin
- LFLex Fridman
How hard is it to simulate all of the things that we've been talking about, each of the things we've been talking about? And maybe one day all of the things we've been talking about and beyond? Meaning, like from the initial primordial solar system, you know, bunch of disks with, I don't know, billions, trillions of objects in them. Like simulate that such that you eventually get a Jupiter and a Saturn, and then eventually you get the Jupiter and the Saturn that clear out a disk, change the gravitational landscape, then Earth pops up, like that whole thing. And then be able to do that for every other system in the, uh, every other star in the galaxy, and then be able to do that for other galaxies as well.
- KBKonstantin Batygin
Um, yeah. So, (laughs) look-
- LFLex Fridman
'Cause maybe start from the smallest simulation-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... like what is actually being done today. I mean, even the smallest simulation is probably super, super diff- even just like one object in the Kuiper belt is probably super difficult to simulate.
- KBKonstantin Batygin
I mean, I think it's super easy.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
I mean, like, it's-
- LFLex Fridman
Okay.
- KBKonstantin Batygin
... it's just not that hard. Um-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... but, um, you know, let's, let's ask the most, kind of basic problem, okay? So, the problem of having a star and something in orbit of it. That-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... you don't need a simulation for. Like, you- you can just write that down on a piece of paper.
- LFLex Fridman
Mm-hmm. There's gravity, what, like ... Yeah, I guess, I guess it's important to try to, uh, you know, one way to simulate objects in our solar system is to build a universe from scratch.
- KBKonstantin Batygin
Okay. We'll get to building the universe from scratch-
- LFLex Fridman
Okay.
- KBKonstantin Batygin
... in a sec, um, but let me just kind of go through the hierarchy of what, you know, what-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... what we do.
- LFLex Fridman
Two objects.
- KBKonstantin Batygin
Right, it's two objects, analytically solvable, like we can figure it out very easily if you just ... You don't even, I don't think you, yeah, you don't need to know calculus. Uh, it helps to know calculus, but you don't necessarily need to know calculus. Um, three objects that are gravitationally interacting, the solution is chaotic. Doesn't matter how many simulations you do, you, the answer loses meaning after, um, after some time.
- LFLex Fridman
I feel like that is a metaphor for dating as well, but go on.
- KBKonstantin Batygin
(laughs) Now, look-
- LFLex Fridman
I apologize.
- KBKonstantin Batygin
Yeah. So, so, the fact that you go from analytically solvable to unpredictable, you know, when you are-... you know, when your simulation goes from two u- bodies to three bodies, should immediately tell you that the exercise of trying to engineer a calculation where you form the solar, entire solar system from scratch and hope to have some predictive answer is, is a futile one. Right? We will never, uh, succeed at such a simulation.
- LFLex Fridman
I feel like, sorry, just to clarify, you mean, like, explicitly having a clear equation that generalizes the, the whole process enough to be able to make a prediction?
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
Or do you mean actually, like, literally simulating the objects is a hopeless pursuit once it increases beyond three?
- 38:50 – 43:17
Quantum mechanics in evolution of objects in the Solar system
- KBKonstantin Batygin
the solar system.
- LFLex Fridman
You mentioned quantum mechanics.
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
And we're, we're talking about cosmic scale objects. You've talked about that the evolution of astrophysical discs can be modeled with, uh, Schrodinger's equation.
- KBKonstantin Batygin
I sure did.
- LFLex Fridman
W- why (laughs) ?
- KBKonstantin Batygin
(laughs)
- LFLex Fridman
Like, how does quantum mechanics, uh, become relevant at, when you, uh, consider the evolution of objects in a solar system?
- KBKonstantin Batygin
Yeah. Well, let me take a, take a step back and just say it, like, I remember being, you know, utterly confused by quantum mechanics when, when I first learned it. And the Schrodinger equation, which is kind of the parent equation of, of that whole field, you know, seems to come out of nowhere, right? The way that, uh, the way that I was sort of explaining it, I remember asking, you know, my professor, I was like, "But, but where does it come from?" He said, like, "Well, just, just, like, don't worry about it, and just, like, calculate the hydrogen, you know, energy levels." Right? So, the, it's like, I could do all the problems, I just did not have any intuition for, for where this parent, you know, super important equation came from. Now, down the line, I was, remember I was preparing for my own lecture, and I was trying to understand how waves, um, travel in self-gravitating discs.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
So, uh, you know, again, there's a very broad theory that's already developed, but I was looking for some simpler way to explain it, really, for the purposes of teaching class. And so, I, I thought, "Okay, what if I just imagine a disc as an infinite, uh, number of concentric circles, right? That interact with th- with each other gravitationally." That's a problem in some sense that, um, I can solve using methods from, like, the s- late 1700s, right?
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
I can write down Hamiltonian ... Well, I can write down the energy function, basically, of their, their interactions. And what I found is that when you take the continuum limit, when you go from discrete circles that are talking to each other gravitationally to a continuum disc, suddenly this gravitational interaction among them, right, the, the governing equation becomes the Schrodinger equation.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
And I had to think about that for a little bit.
- LFLex Fridman
Did you just unify (laughs) -
- KBKonstantin Batygin
(laughs)
- LFLex Fridman
... quantum mechanics and gravity?
- KBKonstantin Batygin
No. This is not the same thing as, like, you know, fusing relativity and quantum mechanics, but it did, uh, it (laughs) it did get me thinking a little bit. Uh, so the fact that waves in astrophysical discs behave just like wave functions of, of particles is kind of, like, an interesting analogy, because for me it's easier to imagine waves traveling through, you know, astrophysical discs, or really just sheets of paper.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
And the reason this is, um, that analogy exists is because there's actually nothing quantum about the Schrodinger equation. The Schrodinger equation is just a wave equation, and all of the interpretation that comes from it is quantum, but the equation itself is not a quantum being, uh-
- LFLex Fridman
So you can use it to model waves. It's w-
- KBKonstantin Batygin
Yes.
- LFLex Fridman
It's not turtles, it's waves all the way down, and you can pick which level you pick the w- the wave at, uh, so it could be at the solar system level that you can use it.
- KBKonstantin Batygin
Right. And also, it actually provides, uh, a pretty neat calculational tool because, um, as r- as I ... It's, it's difficult, so we just talked about simulations, but it's difficult to simulate the behavior of astrophysical discs on time scales that are in between a few orbits and their entire evolution.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
So, it's over a time scale of a few orbits, you have, you do a hydrodynamic, you know, simulation-... right? You do, um, that basically, that's something that you can do on a modern computer, on a timescale of say a week.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
When it comes to their evolution over their entire lifetime, you don't hope to resolve the orbits. You just kind of hope to understand how the system behaves
- NANarrator
Mm-hmm.
- 43:17 – 49:04
Simulating the first formations around the Sun
- KBKonstantin Batygin
- LFLex Fridman
That's fascinating. By the way, the astrophysical disks, how, uh, w- what are they? How broad is this definition?
- KBKonstantin Batygin
Okay. So astrophysical disks span a huge, uh, huge amount of ranges. Um, they start maybe at the smallest scale. They start with actually Kuiper Belt objects. Some Kuiper Belt objects have rings, okay?
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
So that's maybe the smallest example of an astrophysical disk. You got this little potato-shaped asteroid-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... you know, which is, you know, sort of the size of LA or something, and around it is, are some rings-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... of icy matter. That object is a small astrophysical disk. Then you have Saturn-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... and rings of Saturn. You have the next set of scale, you have the solar system itself when it was forming, you have a disk. Then you have black hole disks. Uh, you have galaxies. Disks are super common in the universe, and the reason is that stuff rotates.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
(laughs) Right? I mean, that's-
- LFLex Fridman
Gravity works.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
So, uh, and th- those rings could be the material that, uh, composes those rings, could be... it could be gas, it could be solid, it could be anything?
- KBKonstantin Batygin
That's right. So, uh, the disk that made... from which the planets emerged was predominantly hydrogen and helium gas. On the other hand, the rings of Saturn are made up of, you know, icicle, ice, little like ice cubes this big, about a centimeter across.
- LFLex Fridman
That sounds refreshing. So, uh, that's incredible.
- KBKonstantin Batygin
(laughs)
- LFLex Fridman
Hydrogen and helium gas. So, in the beginning, it was just hydrogen and helium-
- KBKonstantin Batygin
Uh-huh.
- LFLex Fridman
... around the sun. How does that lead to the first formations of solid objects-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... uh, in terms of simulation?
- KBKonstantin Batygin
Okay. Here's the story. Um, so you like... have you ever been to the desert? (laughs) Okay.
- LFLex Fridman
Yes. I've been to the Death Valley, and actually it was, uh, terrifying just as... total tangent. I'm distracting you.
- KBKonstantin Batygin
Mm-hmm. No problem.
- LFLex Fridman
But I was, uh, uh, driving through it, and I was really surprised because it was at first hot and then as it was getting into the evening, there's this huge thunderstorm. Like-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... it was raining, and it got freezing cold. Like what the hell's... it was the apocalypse.
- 49:04 – 51:24
Will it be possible to simulate the full history of the Solar System?
- LFLex Fridman
So, do you think one day it will be possible to simulate the full history that took our solar system to what it is today?
- KBKonstantin Batygin
Yes, and it will be useless. (laughs)
- LFLex Fridman
Okay. (laughs) So you don't think your story, many of the ideas that you have about Jupiter clear in the space, like retelling that story in high resolution is not that important?
- KBKonstantin Batygin
I actually think it's important, but at every stage you have to, you have to simul- you have to design your experiments, your, your numerical computer experiments, so that they test some specific aspect of that evolution.
- LFLex Fridman
Got it.
- KBKonstantin Batygin
Um, I am not a proponent of doing huge simulations, because, um, even if we forget the information theory aspect of not being able-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... to simulate in full detail the universe, because if you do, then you, you have made an actual universe, it's not a simulation, right? By... Simulation is, in some sense, a compression-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... of information, so therefore you loo- must lose detail. But that point aside, if we are able to simulate the entire history of the solar system in excruciating detail, I mean, it'll be cool, but it's not gonna be any different from observing it.
- LFLex Fridman
Right.
- KBKonstantin Batygin
Right? Because theoretical understanding, which is what ultimately I'm interested in, um, comes from taking complex things and reducing them down to something that, you know, some mechanism-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... that you can actually quantify. Um, that's the, that's the fun part of astrophysics. Just kind of simulating things in extreme detail is, well, cool, we'll make cool visualizations, but that doesn't get to, doesn't, doesn't get you to any better understanding than you had before you did the simulation.
- LFLex Fridman
If you ask very specific questions, then you'll be able to, uh, create, like, very highly compressed, nice, beautiful theories about how things evolved, and then you can use those to then generalize to other solar systems, to, uh, other stars and other galaxies and say something generalizable about the entire universe.
- 51:24 – 53:45
How far should we go with the simulation?
- LFLex Fridman
How difficult would it be to simulate our solar system such that we would not know the difference? Meaning, if we are living in a simulation, is there a nice... Think of it as a video game.
- KBKonstantin Batygin
Mm-hmm. Sure.
- LFLex Fridman
Is there a nice compressible way of doing that? Or just kind of like you intuited with the three-body situation, is just a giant mess that you cannot create a video game that, uh, will seem realistic without actually building a universe from scratch?
- KBKonstantin Batygin
Well, so, uh, I'm, you know, I'm speculating, but one-
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
... of the... Yeah, I know, I know you, like, you have a deep understanding of this, uh, but, like, m- for me, I, I'm, I'm just gonna, like, speculate that for, um, at least in the types of simulations that we can do today, inevitably you run into the problem of resolution, right? Your... It doesn't matter what you're doing, it is discrete. Now, um, the way you would go about asking, you know, if what we're observing, is that a simulation or, uh, or is that, you know, some real continuous thing-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... uh, is you, you zoom in, right? You zoom in and try and find the, you know, the grid scale, if you will.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Um, yeah. I mean, it's a, it's a really interesting, it's a really interesting question, and because the solar system itself, and really, you know, the double pendulum is chaotic, right? Pendulum sitting on another pendulum, it moves unpredictably once you let them go. Um, you really don't need to, like, inject any randomness into a simulation for it to, to give you stochastic and unpredictable answers. Weather is a great example of this. Weather has a lapin of time of, you know, typical weather systems have a lapin of time of a few days. And there's a fundamental reason why the force... forecast always sucks, you know, two weeks in advance. It's not that we don't know the equations that govern the atmosphere. We know them well. Their solutions are meaningless though after a few days.
- LFLex Fridman
The zooming in thing is very interesting.
- 53:45 – 1:00:10
Increasing immersion in video games
- LFLex Fridman
I, I, uh, think about this a lot, whether there'll be a time soon where we would want to stay in video game worlds, whether it's virtual reality or just playing video games.
- KBKonstantin Batygin
I mean, I think that time, like, came in, like, the '90s, and it's been that time.
- LFLex Fridman
Well, it's not just, it's not just came, it's, I mean, it's accelerated. I just recently saw that WoW and Fortnite were played 140 billion hours, and those are just video games.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
And that's, like, increasing very, very quickly, especially with the people coming up now, and being born now and become, you know, becoming teenagers-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... and so on. Let's have a thought experiment wh- ... it's just you and a video game character inside a room. Where you remove the simulation, the need to simulate sort of, um, a lot of objects. If it's just you and that character, how far do you need to simulate in terms of zooming in for it to be very real to you?
- KBKonstantin Batygin
Oh, uh, yeah.
- LFLex Fridman
As real as reality. So, like, first of all-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... you kind of mentioned zooming in, which is fascinating, because we have these tools of science that allow us to zoom in, quote-unquote, in all kinds of ways.... a- a- and the world around us, but our cognitive abilities, like our perception system as humans is very limited in terms of zooming in.
- KBKonstantin Batygin
Oh, sure. Yeah.
- LFLex Fridman
So we might be very easily fooled.
- KBKonstantin Batygin
Some of the video games, like, on the PS4-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... like, look pretty real to me.
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Right? Uh, I think, you know, you would really have to interrogate... uh, I mean, I think even with what we have today, like, uh, I don't know, Ace Combat 7 is a great example, right?
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Like, I mean, the way that the clouds are rendered, uh, it's... I mean, looks just like when you're flying, you know, on a real airplane-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... the, the kind of transparency. I think that the, you know, our perception is limited enough already-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... to not be able to tell some of the, uh, you know, some of the differences.
- LFLex Fridman
There's a game called, uh, Skyrim, it's an Elder Scrolls role-playing game. And I just, uh, I played it for quite a bit.
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
And I (laughs) think I played it very different than others. Like, there'll be s- long stretches of time where I would just walk around and look at nature in the game.
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
It's incredible.
- KBKonstantin Batygin
Oh, sure.
- 1:00:10 – 1:06:39
What is Planet Nine?
- KBKonstantin Batygin
- LFLex Fridman
So, let me return us back to Planet Nine.
- KBKonstantin Batygin
Uh-huh. Always a good place to come back to.
- LFLex Fridman
So now that we did a big historical overview of our solar system, what is Planet Nine?
- KBKonstantin Batygin
Okay. Planet Nine is a hypothetical object that orbits the solar system, right? Uh, on orbital period of about 10,000 years and, um, an orbit which is, uh, slightly tilted with respect to the plane of the solar system, slightly eccentric, and the object itself we think is five times more massive than the Earth. We have never seen Planet Nine in a telescope, but we have gravitational evidence for it.
- LFLex Fridman
And so this is where all the stuff we've been talking about, this clustering ideas, maybe you can speak to the approximate location that we suspect. And also the question I wanted to ask is, uh, what are we supposed to be imagining here? 'Cause you said there's certain objects in the Kuiper Belt that are... kind of have a direction to them, that they're all like-... like flocking in some kind of way. Mm-hmm. So that's the sense that there is some kind of gravitational object not changing their orbit, but kind of ...
- KBKonstantin Batygin
Confining them, right?
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
Confining, like grouping their orbits together. See, what would happen if Planet Nine were not there, is these orbits that roughly share a common orientation, they would just disperse, right? They would just become asym- asymmetry symmetric point everywhere. Planet Nine's gravity makes it such that these objects stay in a state that's- that's basically anti-aligned, with respect to the orbit of Planet Nine. Um, and- and sort of hang out there and kind of oscillate on time scale of about a billion years. That's one of the lines of evidence for the existence of Planet Nine. There are others. That's the one that's easiest to maybe visualize just because it's fun to think about orbits that all point into the same direction. But I should, um, you know, emphasize that, for example, the existence of objects, again, Kuiper Belt objects, that are heavily out of the plane of the solar system, things that are tilted by, say, 90 degrees, that's not... Uh, we don't expect that as an outcome of planet formation. Indeed planet formation simulations have never produced such objects without some extrinsic gravitational force.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Planet Nine on the other hand, generates them very readily. So that p- uh, provides kind of an alternative, you know, population of small bodies in the solar system that also get produced by Planet Nine through an independent kind of gravitational effect. So there are kind of... There's basically five different things that the, uh, that Planet Nine does individually that are like kind of maybe a one sigma effect where you'd say, "Yeah, okay. If that's all it was, maybe it's not... No reason to jump up and down." But because it's- it's mul- it's a multitude of these puzzles that all are explained by one hypothesis, that's- that's really the- the magnetism, the attraction of the Planet Nine model.
- LFLex Fridman
So, can you just clarify?
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
(laughs) So most orbit, most planets in the solar system orbit at approximately the same, so it's flat?
- KBKonstantin Batygin
That's right. Yeah, it's like one degree. They, the difference between them is o- about one degree.
- LFLex Fridman
So, but, nevertheless, if we looked at our solar system, it would look... And I could see every single object, it would look like a sphere?
- KBKonstantin Batygin
The inner part where the planets are would look like-
- LFLex Fridman
Flat.
- KBKonstantin Batygin
... you know, flat, right? The- the Kuiper Belt and the asteroid belt have a larger, um...
- LFLex Fridman
It gets fatter and fatter and fatter-
- KBKonstantin Batygin
Yeah, it's kind of like this.
- LFLex Fridman
... until it becomes a sphere.
- KBKonstantin Batygin
That's right. And if you look at the very outside, it's polluted by this, you know, quasi-spheroidal thing. Nobody's, of course, ever seen the Oort cloud, right? We've only seen comets that come from the Oort cloud. So the Oort cloud, which is this, right, population of distant debris, its existence is also inferred. You could say alternatively there is, you know, there's a big cosmic creature that occasionally... You know, it's sitting at 20,000 AU and occasionally throws an icy rock-
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
... towards the s- sun like that-
- LFLex Fridman
Spaghetti monster, I think-
- KBKonstantin Batygin
Right.
- LFLex Fridman
... it's called.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
Okay. You know, I mean (laughs) . S- so it's a mystery in many ways but you can kind of infer a bunch of things about it. It's- it's, by the way, both terrifying and exciting that there's this vast darkness all around us that's full of objects that are just throwing ...
- 1:06:39 – 1:09:03
The origin of life
- LFLex Fridman
Do you think it's possible that life from other solar systems was injected and that that was what was, uh, the origin of life on Earth?
- KBKonstantin Batygin
Yeah, the panspermia idea. Um ...
- LFLex Fridman
That- that's seen as a low probability event by people who study the origin of life but that's because, uh, then they would be out of a job (laughs) .
- KBKonstantin Batygin
(laughs) . Well, I don't think they'd be out of a job 'cause you just didn't say, you have to figure out how life started on there.
- LFLex Fridman
But then you have to go there. We can study life on Earth much easier, we could study it in a lab much easier because we could replicate conditions there, uh, from an early L- um, Earth much easier from a chemistry perspective, from a biology perspective. You can intuit a bunch of stuff, you can look at different parts of Earth and just ...
- KBKonstantin Batygin
To an extent. I mean, the early Earth was completely unlike the current Earth, right?
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
There was no oxygen. So, uh, one of my colleagues at Caltech, uh, Joe Kirschnik, uh, is-... um, certain, right. W- something like 100% certainty-
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
... that life started on Mars and came to Earth, uh, in, on Martian meteorites. Um.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
This is not a problem that I like to, kind of, think about too much, like the origin of life. It's a fascinating problem, but, you know, it's not physics, and I just, like, I just don't, don't love it.
- LFLex Fridman
It's the same reason you don't love... I, I thought you were a musician.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
So music, music is not physics either, so why, why are you so into-
- KBKonstantin Batygin
It's 100% physics. (laughs)
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
Okay.
- KBKonstantin Batygin
No, no, no, look-
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Uh, in all seriousness though, I, uh, there are a few things that I really, really enjoy. I genuinely enjoy physics, I genuinely enjoy music, I genuinely, you know, enjoy martial arts, and I genuinely enjoy, uh, my family. I should have said that all in a reverse order or something. But I like to focus on these things and, and not worry too much about, about everything else. You know what I mean?
- LFLex Fridman
Yes.
- KBKonstantin Batygin
Just because there is a, like you said earlier, there's a time constraint. You can't do it all.
- LFLex Fridman
There's many mysteries all around us. So, um, and they're all beautiful in, in different ways. To me, that thing I love is artificial intelligence.
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
That, uh, perhaps I love it because eventually I'm trying to suck up to our future overlords. The, um,
- 1:09:03 – 1:11:33
Evidence of Planet Nine
- LFLex Fridman
the question of... You said there's a lot of, kind of, little pieces of evidence for this thing that's Planet Nine. If we were to try to collect more evidence, or be certain, like a paper that says, like, you drop it, clear, we're done. What, what does that require? Does that require-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... us sending probes out, or do you think we can do it from telescopes here on Earth? What, what are the different ideas for conclusive evidence for Planet Nine?
- KBKonstantin Batygin
The moment Planet Nine gets imaged from a telescope on Earth, it's done. I mean, it's just there.
- LFLex Fridman
Can you clarify, because you, you mentioned that before, from an image, would you be able to tell?
- KBKonstantin Batygin
Yes. So from an image, the moment you see something, something that is reflecting sunlight back at you, and you know that it's hundreds of times as far away from-
- LFLex Fridman
Ah.
- KBKonstantin Batygin
... the sun as is, as is the earth, you're done.
- LFLex Fridman
So you're, you're thinking, so basically, if you have a really far away thing that's big-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... you know, five times the size of Earth, that means, uh, that-
- KBKonstantin Batygin
That is-
- LFLex Fridman
... that's Planet Nine.
- KBKonstantin Batygin
That is Planet Nine.
- LFLex Fridman
Could there be multiple objects like that? I guess-
- KBKonstantin Batygin
In principle, yeah. I mean, there's no, there's no law of physics that, uh, that doesn't allow you to have multiple objects. There's also no evidence at present for there being multiple objects.
- LFLex Fridman
I wonder if there... it's possible, so it's like, just like we're finding exoplanets-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... whether given the size of the Oort cloud, there's basically, it's rarer and rarer, but they're sprinkled Planet Nine, 10, 11, 12, like these-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... some-
- KBKonstantin Batygin
You got 13.
- LFLex Fridman
Yeah, it goes after that.
- KBKonstantin Batygin
(laughs) Yeah. So... (laughs)
- LFLex Fridman
I can just keep counting. So, like, just something about the dynamic-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... system, like, it becomes lower and lower probability event, but they gather up, like, they, they become, would they become larger and larger maybe, something like that. And I wonder, I wonder if, like, discovering Planet Nine will, will just, like, be almost like a springboard, it's like, well, what's, what's beyond that?
- KBKonstantin Batygin
It's entirely plausible. The Oort cloud itself probably holds about five Earth masses or seven Earth masses of material, um, right? So it's not, it's not nothing. And the... it all ultimately comes down to at what point will the observational surveys sample enough of the solar system to, uh, kind of reveal interesting things.
- LFLex Fridman
Mm-hmm.
- 1:11:33 – 1:12:43
Discovery of Neptune
- LFLex Fridman
- KBKonstantin Batygin
There's a great analogy here with Neptune and the story of how Neptune was discovered. Neptune was not discovered by looking at the sky, right? It was discovered by, uh, it was discovered mathematically, right? So-
- LFLex Fridman
Oh.
- KBKonstantin Batygin
Uh, yeah, the orbit of Uranus, when Uranus was found, um, this, this was 1781. Uh, it's the kind of tracking of... both the tracking of the orbit of Uranus as well as the reconstruction of the orbit of Uranus immediately revealed that it was not following the orbit that it was supposed to, right? The, the predicted orbit deviated away from where it actually was. So, uh, in the mid-1800s, right, um, a French mathematician by the name of Urbain Le Verrier did a beautifully sophisticated calculation which said, if this is due to gravity of a more distant planet, then that planet is there.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Okay? And then they found it. But the point is, the understanding of where to look for Neptune came entirely out of celestial mechanics.
- 1:12:43 – 1:15:22
When will we find Planet Nine?
- KBKonstantin Batygin
The case with Planet Nine is a little bit different, because what we can do, I think relatively well, is predict the orbit and mass of Planet Nine. We cannot tell you where it is on its orbit. The reason is we haven't seen the Kuiper Belt objects complete an orbit, their own orbit-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... even once, because it takes 4,000 years. But, you know, I plan to live on as an AI being, uh, and, you know, I'll, I'll be tracking those, uh, those orbits as, you know-
- LFLex Fridman
So all it takes-
- KBKonstantin Batygin
... for-
- LFLex Fridman
... 4,000 or 5,000 years, I mean, it could, it doesn't have to be AI, it could be longevity. There's a lot of really exciting genetic engineering research. So you'll, you'll just be a brain waiting for the (laughs) for the, your brain waiting for the orbit to complete for the basic Kuiper Belt objects.
- KBKonstantin Batygin
That's, that's right. That's like kind of the worst reason to want to live a long time, right? (laughs)
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Just like, can the brain, like, smoke a cigarette?
- LFLex Fridman
I know, right?
- KBKonstantin Batygin
Right. Can you just-
- LFLex Fridman
It's like-
- KBKonstantin Batygin
... light one up while you're waiting or...
- LFLex Fridman
(laughs) Uh...But you make me actually realize that the one way to explore the, the galaxy is by just sitting here on Earth and waiting. (laughs) So, if we can just get really good at waiting, it's like ʻOumuamua or these interstellar objects that fly in, you can just wait for them to come to you. Same with the aliens, you can wait for them to come to you. If you get really good at waiting, um, then that's one way to do the exploration because eventually the thing will come to you. Maybe that's the enti- maybe the il- intelligent alien civilizations get much better at waiting, and so they all decide, so game theoretically, to start waiting, and it's just a bunch of, like, ancient intelligent civilizations of aliens all throughout the universe that are just sitting there waiting for each other.
- KBKonstantin Batygin
Look, you can't just be good at waiting. You gotta know how to chill, okay?
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Like, like, you can't just, like, sit around and do nothing. You gotta be- you gotta, you gotta know how to chill.
- LFLex Fridman
I honestly think that as we progress-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... if the aliens are anything like us, we enjoy loving things we do. And it, it's, uh, it's very possible that we just figure out mechanisms here on Earth to enjoy our life-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... and we just stay here on Earth fore- e- uh, forever, that exploration becomes less and less of an interesting thing to do. And so you basically, yes, wait and chill. (laughs)
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
You get really optimally good at chilling, and thereby exploring, uh, uh, is not that, uh, interesting.
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
So, you know, in, in terms of 4,000 years, it would be nothing for scientists. We'll be chilling and just all kinds of scientific explorations will become possible because we'll just be here on Earth.
- KBKonstantin Batygin
So chill.
- LFLex Fridman
(laughs) So
- 1:15:22 – 1:19:17
Planet Nine throws rocks into the Kuiper Belt
- LFLex Fridman
chill.
- KBKonstantin Batygin
So chill.
- LFLex Fridman
You have a paper out recently, 'cause y- you already mentioned some of these ideas, but I'd love it if you could dig into it a little bit.
- KBKonstantin Batygin
Yeah, of course.
- LFLex Fridman
The injection of inner Oort cloud objects into the distant Kuiper belt by Planet Nine. What is this idea of, uh, Planet Nine injecting objects into the Kuiper belt?
- KBKonstantin Batygin
Okay, let me take a, a brief step back and say when we do calculations of Planet Nine, when we do the simulations, as far as our simulations are concerned, sort of the, uh, Neptune, like, kind of the, the Nept- trans-Neptunian solar system is entirely sourced from the inside. Namely, the Kuiper belt gets scattered by Neptune, and then Planet Nine does things to it and aligns the orbits and, and so on. And w- and then we calculate what, uh, what happens on the lifetime of the solar system, yada, yada, ya. Um, during the pandemic, one of the, kind of, questions we asked o- ourselves, and this is indeed something we, Mike and I, um, Mike Brown who's a partner in crime on this, and I do regularly, is we say, "How can we, A, disprove ourselves, and B, how can we improve our simulations? Like, what's missing?"
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
And one idea we, that maybe should have been obvious in retrospect is that all of our simulations treated the solar system as some isolated creature, right? But the solar system did not form in isolation, right? It formed in this cluster of stars. And during that phase of forming together with thousands of other stars, we believe the solar system formed this almost spherical population of icy debris that sits maybe at a few thousand times the (clears throat) separation between the Earth and the sun, maybe even a little bit closer. If Planet Nine is not there, that population is completely dormant, right? These objects just slowly orbit the, the sun, nothing interesting ha- happens to them ever. But what we realize is that if Planet Nine is there, Planet Nine can actually grab some of those objects and gravitationally re-inject them-
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
... into the distant solar system. So, we thought, "Okay, let's look into this with numerical experiments, do, do our simulations. Does this process work? And if it works, uh, what are its consequences?" So, it turns out, indeed, not only does Planet Nine inject these distant k- um, inner Oort cloud objects into the Kuiper belt, they follow roughly the same pathway as the, um, as the objects that are being scattered out. Also, there's this kind of river, two-way river of material. Some of it is coming out from, you know, by Neptune scattering, some of it is moving in. And if you work through the numbers, you kind of, at the end of the day, that it, it ch- has an effect on the best fit orbit for Planet Nine itself. So, if you realize that the data set that we're observing is not entirely composed of things that came out of the solar system, but also things that got re-injected back in, then turns out the best fit Planet Nine slightly more eccentric, that's kind of getting into the weeds. The, the point here is that, uh, you know, the existence of Planet Nine itself provides this natural bridge that connects an otherwise dormant population of icy debris of the solar system with things that we're starting to directly observe.
- LFLex Fridman
So, it can flow back, so it's not just a river-
- KBKonstantin Batygin
Yeah.
- LFLex Fridman
... flowing one way, it's maybe a smaller stream going back, and-
- KBKonstantin Batygin
Backwash.
- LFLex Fridman
You want a backwash.
- KBKonstantin Batygin
(laughs)
- LFLex Fridman
You want to incorporate that into the simulations, into your understanding of those distant objects when you're trying to make sense-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... of the various observations and so on.
- KBKonstantin Batygin
Exactly.
- LFLex Fridman
That's fascinating.
- 1:19:17 – 1:29:21
Could Planet Nine be a primordial black hole?
- LFLex Fridman
I gotta ask you, some people think-
- KBKonstantin Batygin
Mm-hmm.
- LFLex Fridman
... that, uh, many of the observations that you're describing could be described by a primordial black hole. First, what is a primordial black hole, and what do you think about this idea?
- KBKonstantin Batygin
Yeah. So, a primordial black hole is a black hole which is made not through the usual pathway of making a black hole, um, which is that you have a star which is, uh, more massive than, you know, 1.4 or so solar masses, and basically when it runs out of fuel-... uh, runs out of its nuclear fusion fuel. It can't hold itself up anymore and just the whole thing collapses on itself. (imitates explosion) Right?
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
You create a, um... I mean, one, I guess, simple way to think about it is you create an object with zero radius, uh, that has mass but zero radius, uh, singularity.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
Um, now, that's... Such black holes exist all over the place. In the galaxy there's in fact a really big one at the center of the galaxy that's like-
- LFLex Fridman
Yeah, that one terrifies me.
- KBKonstantin Batygin
Yeah. That w- that one's always looking at you when you're not looking, okay?
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Right? And it's- it's always talking about you.
- LFLex Fridman
And when you turn off the lights it s- it wakes up.
- KBKonstantin Batygin
That's right.
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
Um, but, you know, so such black holes are all over the place. We... When they merge we get to see, you know, incredible gravitational waves that they emit, et cetera, et cetera. One kind of plausible scenario however, is that when the universe was forming, basically during the Big Bang, you created a whole spectrum of black holes, uh, some with masses of five Earth masses, some with masses of 10 Earth masses, like the entire, you know, mass spectrum size, the ma- some the mass of asteroids. Now, on the smaller end over the lifetime of the universe, the small ones kind of evaporate, uh, and they're not there anymore. At least this is what we, uh, what the calculations tell us. Um, but five Earth masses is big enough to not have evaporated. So one idea is that Planet Nine is not a planet and instead it is a five Earth mass black hole, and that's why it's hard to find. Now, um, can we right away from our calculations say that's definitely true or that's not true? Absolutely not. We can't... In fact, our calculations tell you nothing other than the orbit and the mass.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
And that means the black hole, I mean, it could be a five Earth mass, you know, cup.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
It could be a five Earth mass hedgehog or a black hole, or- or really anything that's five Earth masses will do because the gravity of a black hole is no different than the gravity of a planet, right? If the sun became a black hole tomorrow it would be dark but Earth- the Earth would keep orbiting it. And, uh, like this notion that all black holes suck everything in, it- it's- it's not.
- LFLex Fridman
Mm-hmm.
- KBKonstantin Batygin
That's like a sci-fi notion.
- LFLex Fridman
Right, it's just mass. What would be the difference between a black hole and a planet in terms of observationally?
- KBKonstantin Batygin
Uh, observationally the difference would be that you will never find a black hole, right?
- LFLex Fridman
(laughs)
- KBKonstantin Batygin
The truth is they're kind of, um... I'm actually not, you know, uh... I never looked into this very carefully but there- there are some constraints that you can get to statistically say, okay, if the sun has a binary companion which is a five Earth mass black hole, then that means bla- such black holes would be extremely common and, you know-
- LFLex Fridman
Yeah.
- KBKonstantin Batygin
... you could s- sort of look for lensing events and then you say, "Okay, maybe that's not so likely." But, you know, that said, I wanna emphasize that there's a limit to what our calculations, uh, can tell you. That's the orbit and the mass.
- LFLex Fridman
So I think there's a bunch... Like, Ed Witten, I think-
- KBKonstantin Batygin
Mm-hmm.
- 1:29:21 – 1:36:48
Commercial space revolution boosts science and the human condition
- KBKonstantin Batygin
Episode duration: 2:39:53
Install uListen for AI-powered chat & search across the full episode — Get Full Transcript
Transcript of episode tm7poMupE8k
Get more out of YouTube videos.
High quality summaries for YouTube videos. Accurate transcripts to search & find moments. Powered by ChatGPT & Claude AI.
Add to Chrome