Konstantin Batygin is a planetary astrophysicist at Caltech. Please support this podcast by checking out our sponsors:
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EPISODE LINKS:
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OUTLINE:
0:00 - Introduction
1:18 - Overview of our Solar System
16:16 - What is the Oort Cloud?
21:11 - Life in the interstellar medium
22:44 - Are there aliens out there?
25:23 - How unique is Earth?
28:04 - Did Jupiter destroy early planets?
34:18 - How hard is it to simulate the Universe?
38:50 - Quantum mechanics in evolution of objects in the Solar system
43:17 - Simulating the first formations around the Sun
49:04 - Will it be possible to simulate the full history of the Solar System?
51:24 - How far should we go with the simulation?
53:45 - Increasing immersion in video games
1:00:10 - What is Planet Nine?
1:06:39 - The origin of life
1:09:03 - Evidence of Planet Nine
1:11:33 - Discovery of Neptune
1:12:43 - When will we find Planet Nine?
1:15:22 - Planet Nine throws rocks into the Kuiper Belt
1:19:17 - Could Planet Nine be a primordial black hole?
1:29:21 - Commercial space revolution boosts science and the human condition
1:36:48 - Solving sex in space
1:37:26 - Would humans evolve if we couldn't see the stars?
1:43:09 - Military funding and science
1:47:13 - Is Oumuamua space junk from a distant alien civilization?
2:00:35 - Wild ideas create the future
2:08:24 - The perfect place to die
2:10:05 - Greatest song of all time
2:16:35 - Music enables science for Konstantin
2:18:53 - Music practice tips for busy people
2:22:43 - Memories of 1990s Russia
2:29:15 - Advice for young people
2:35:11 - Meaning of life

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The following is a conversation with Konstantin Batygin, planetary astrophysicist at Caltech, interested in, among other things, the search for the distant, the mysterious Planet 9 in the outer regions of our solar system.

Quick mention of our sponsors, Squarespace, Litterati, 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 3 light years out.

This to me is amazing, since Proxima Centauri, the closest 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.

Or at the very least, AI systems that carry the flame of human consciousness.

This is the Lux Friedman Podcast, and here's my conversation with Konstantin Batygin.

Planet 9 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 is about 5 Earth masses.

There's some evidence for this kind of object.

There's a bunch of different explanations.

Can you give 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?

So look, the solar system basically is comprised of 2 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.

further away from the Sun than is the Earth.

These planets that we occupy are pretty small.

They're 2 leading order, sort of heavily overgrown asteroids, if you will.

And this becomes evident when you move out further in the solar system and encounter Jupiter, which is

You know, and Saturn is another huge 1, 90 Earth masses at about 10 times the separation from 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's this expansive field of icy debris, a second icy asteroid belt in the solar system.

A lot of people have heard of the asteroid belt, which lives between Mars and Jupiter.

That's a pretty common thing that people like to imagine and draw on lunchboxes and stuff.

But beyond Neptune, there's a much more massive, much more radially expansive 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.

Pluto, the dwarf planet, the former planet.

So size matters when it comes to planets.

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.

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 just a point mass star rather than a physical disk.

They said, well, maybe it's not 7, maybe it's 1, right?

And then sort of over the next, you know, I guess 40 years, Pluto's mass kept getting revised downwards, downwards, downwards until it was realized that it's like 500 times less massive than the Earth.

I mean, like Pluto's surface area is almost perfectly equal to the surface area of Russia.

Actually, and you know, Russia's big, but it's not a planet.

Well, I mean, actually, we can touch more on that.

So in some sense, earlier in the century, Pluto represented kind of our ignorance about the edges of the solar system.

And perhaps planet 9 is the thing that represents our ignorance about now, the modern set of ignorances about the edges of our solar system.

By the way, just imagining this belt of debris at the edge of our solar system is incredible.

What is the Kuiper belt and what is the Oort cloud?

Yeah, okay, so look, the simple way to think about it is that if you imagine, you know, Neptune's orbit like a circle, right?

Kind of maybe a factor of 1 and a half, 1.3 times bigger, on a radius of 1.3 times bigger, you've got a whole collection of icy objects.

Most of these objects are sort of the size of Austin, you know, maybe a little bit smaller.

If you then zoom out, right, and explore the orbits of the most long period Kuiper Belt object, these are the things that have the biggest orbits and take the longest time to go around the Sun, then what you find is that Beyond a critical orbit size, beyond a critical orbit period, which is about 4,000 years, you start to see weird structure.

All the orbits sort of point into 1 direction.

And all the orbits are kind of tilted in the same way, by about 20 degrees with respect to Sun.

This is particularly pronounced in orbits that are not heavily affected by Neptune.

So there you start to see this weird dichotomy where there are objects which are stable, which Neptune does not mess with gravitationally, and unstable objects.

The unstable objects are basically all over the place because they're being kicked around by Neptune.

The stable orbits show this remarkable pattern of clustering.

We back, I guess, 5 years ago interpreted this pattern of clustering as a gravitational one-way sign, the existence of a planet, a distant planet, something that is shepherding and confining these orbits together.

Of course, right, you have to have some skepticism when you're talking about these things.

You have to ask the question of, okay, how statistically significant is this clustering?

And there are many authors that have indeed called that into question.

And basically, just like with all statistics where there's kind of like multiple ways to do the exercise, you can either ask the question of if I have a telescope that has surveyed this part of the sky, what are the chances that I would discover this clustering?

That basically tells you that you have 0 confidence.

Right, like that does not give you a confident answer 1 way or another.

Another way to do the statistics, which is what we prefer to do, is to say We have a whole night sky of discoveries in the Kuiper belt, right?

And if we have some object over there, which has right ascension and declination, which is a way to say it's there on the sky, and it has some brightness, that means somebody looked over there and discovered an object of, was able to discover an object of that brightness or brighter.

Through that analysis, you can construct a whole map on the sky of kind of where all of the surveys that have ever been done have collectively looked.

So if you do the exercise this way, the false alarm probability of the clustering on which the Planet 9 hypothesis is built is about

Wow, Okay, so there's a million questions here.

1, when you say bright objects, why are they bright?

Are we talking about actual objects within the Kuiper Belt or the stuff we see through the Kuiper Belt?

This is the actual stuff we see in the Kuiper Belt.

The way you go about discovering Kuiper Belt objects, It's pretty easy.

All you do is you take snapshots of the sky, right?

Choose that direction and take, you know, the high exposure snapshot.

Then you wait a night and you do it again.

And then you wait another night and you do it again.

Objects that are just random stars in the galaxy don't move on the sky, whereas objects in the solar system will slowly move.

This is no different than if you're driving down the freeway it looks like trees are going by you faster than the clouds, right?

It's just they're reflecting light off of the sun and it's going back and hitting this.

There's a little bit of a glimmer from the different objects that you can see based on the reflection from the sun.

So like there's actual light, it's not darkness.

That's right, these are just big icicles basically that are just reflecting sunlight back at you.

It's then easy to understand why it's so hard to discover them because light has to travel to something like 40 times the distance between the Earth and the Sun and then get reflected back.

Yeah, that's right, that's something like that because the Earth to the Sun is 8 minutes, I believe.

So you have to account for all of that, and then there's this huge amount of data, pixels that are coming from the pictures, and you have to integrate all of that together to paint a sort of like a high estimate of the different objects.

I mean, I'm not like this is not even a joke.

But like the way it works is if you discover 1, you right away get a license plate for it.

So, like, the first 4 numbers is the first year that this object has appeared on, you know, in the data set, if you will.

And then there's, like, this code that follows it, which basically tells you where in the sky it is.

So 1 of the really interesting Kuiper belt objects, which is very much part of the Planet 9 story is called VP113, because Joe Biden was vice president at the time, you know, got nicknamed Biden.

What's the fingerprint for any particular object?

Or you just kind of like, yeah, from night to night you take a picture, how do you know it's the same object?

Yeah, so the way you know is it appears in almost exactly the same part of the sky except for it moves by it.

And this is why actually you need at least 3 nights, because oftentimes asteroids, which are much closer to Earth, will appear to move only slightly, but then on the third night, we'll move away.

So, that third night is really there to detect acceleration.

Now, the thing that I didn't really realize until, you know, I started observing together with my partner in crime and all this, Mike Brown, is just the fact that for the first year when you make these detections, the only thing you really know with confidence is where it is on the night sky and how far away it is.

You don't know anything about the orbit because over 3 days the object just moves so little Right the that whole motion on the sky is entirely coming from motion of the earth Right.

So the earth is kind of the car the object is the tree and you see it move.

So then to get some confident information about what its orbit looks like, you have to come back a year later and then measure it again.

Oh, interesting, so do 3 nights, then come back a year later and do another 3 nights.

So you get the velocity, the acceleration from the 3 nights, and then you have the maybe, the additional formation.

Because an orbit is basically described by 6 parameters.

So you at least need 6 independent points, but in reality you need many more observations to really pin down the orbit well.

And from that you're able to construct for that 1 particular object an orbit and then there's of course, like how many objects are there?

But like in the future, that could be millions.

In fact, these things are hard to predict, but there's a new observatory called the Vera Rubin Observatory, which is coming online maybe next year.

I mean, with COVID, these things are a little bit more uncertain, but they've actually been making great progress with construction.

And so that telescope is just gonna sort of scan the night sky every day automatically and it's such an efficient survey that it might increase the census of the distant Kuiper belt, the things that I'm interested in by a factor of

Like almost like literally pictures, like visually.

I mean, sure, yeah, like the first detection you make, all you know is where it is in the sky and how far away it is.

If something is 500 times away from the sun, as far away from the sun as is the earth, you know that's planet 9.

I'm gonna use that as like, I don't know, a pickup line or a dating strategy.

Like see the person for 3 days and then don't see them at all and then see them again in a year to determine the orbit and over time you figure out if sort of from a cosmic perspective, this whole thing works out.

I was gonna use this as a metaphor to somehow map it onto the human condition.

Okay, you mentioned the Kuiper Belt, what's the Oort Cloud?

If you look at the Neptune orbit as 1, then the Kuiper Belt is like 1.3 out there,

then we get farther and farther into the darkness.

So, okay, you've got the main Kuiper Belt, which is about, say,

Then you have something called the scattered disk, which is kind of an extension of the Kuiper belt.

It's a bunch of these long, very elliptical orbits that hug the orbit of Neptune but come out very far.

So, the scattered disk with the current senses, like some of the longest orbits we know of, have a semi-major axis, so half the orbit length, roughly speaking, of about a thousand, thousand times the distance between the Earth and the Sun.

Now, if you keep moving out, eventually, once you're at sort of

to 100,000 roughly, that's where the Oort cloud is.

Now, the Oort cloud is a distinct population of icy bodies and is distinct from the Kuiper Belt.

In fact, it's so expansive that it ends roughly halfway between us and the next star.

Its edge is just dictated by to what extent does the solar gravity reach?

Imagining this is a little bit overwhelming.

So there's like a giant, like vast, icy rock thingy.

It's like, you know, it's like it'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 seemingly comes out of nowhere.

The reason these long period comets appear that on very, very long time scales, right?

These Oort Cloud objects that are sitting

times as far away from the Sun as is the Earth actually interact with the gravity of the galaxy, effectively the tide that the galaxy exerts upon them and their orbits slowly change and they elongate to the point where once 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, they look beautiful in the night sky, et cetera, but they're all coming from really, really far away.

So are any of them coming our way from collisions?

Or is there a bunch of space for them to move around?

Yeah, there's 0, 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 collision-less environment.

I don't know, I think that probably in the age of the solar system, There have literally been 0 collisions in the Oort cloud.

When you like draw a picture of the solar system, everything's really close together.

So everything I guess here is 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.

We've seen a couple of them in the last 3 or so years, maybe 4 years now.

The second 1 was Comet Borisov, discovered by a guy named Borisov.

Yeah, so the way you know they're coming from elsewhere is unlike solar system objects which travel on elliptical paths around the sun, these guys travel on hyperbolic paths.

So they come in, say hello, and then they're gone.

And the fact that they exist is totally not surprising.

The Neptune is constantly ejecting Kuiper belt objects into interstellar space.

Our solar system itself is sort of leaking icy debris and ejecting it.

So presumably every, you know, planetary systems around other stars do exactly the same thing.

Let me ask you about the millions of objects that are part of the Kuiper Belt and part of the Oort Cloud, do you think some of them have primitive life?

If there's primitive life there and they're just kind of lonely out there in space.

How many of them do you think have life, bacterial life?

So if you and I took a little trip to the interstellar medium, I think we would develop cancer and die real fast, right?

Yeah, it's a pretty hostile radiation environment.

You don't actually have to go to the interstellar medium, you just have to leave the Earth's magnetic field and then you're not doing so well suddenly.

So, you know, this idea of, you know, life kind of traveling between places, it's not entirely implausible, but you really have to twist, I think, a lot of parameters.

1 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 survival in the interstellar medium and how resilient it is because we think you require water, and that's certainly the case for the Earth, but we really don't know for sure.

That said, I will argue that the question of are there aliens out there is a very boring question, because the answer is of course there are.

I mean, like we know that there are planets around almost every star.

Life is not some specific thing that happened on the earth and that's it, right?

Yeah, but the difficult question is, before even the fact that we don't know how life originates, I don't think we even know what life is, like definitionally.

Like formalizing a kind of picture of, in terms of the mechanism we would use to search for life out there, or even when we're on a planet, to say, is this life?

Is this rock that just moved from where it was yesterday life?

Or maybe not even a rock, something else.

I gotta tell you, I wanna know what life is, okay?

I think there's a song to basically accompany every single thing we talk about today, and probably half of them are love songs, and somehow we'll integrate George Michael into the whole thing.

Okay, so your intuition is there's life everywhere in our universe.

Do you think there's intelligent life out there?

I think there's intelligent life on Earth.

So yeah, taking that, like say, whatever this thing we got on Earth, whether it's dolphins or humans, say that's intelligent.

Well, they do some cruel stuff to each other.

So if cruelty is a definition of intelligence, they're pretty good.

And then humans are pretty good in that regard.

And then there's like pigs are very intelligent.

I got actually a chance to hang out with pigs recently.

And they're, aside from the fact they were trying to eat me, they're very, they love food.

They love food, but there's an intelligence to their eyes that was kind of like haunts me because I also love to eat meat.

And then to meet the thing I later ate, and it was very intelligent and almost charismatic with the way it was expressing himself, herself, itself, was quite incredible.

So all that to say is if we have intelligent life here on Earth, if we take dolphins, pigs, humans, from the perspective of planetary science, how unique is Earth?

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Konstantin Batygin: Planet 9 and the Edge of Our Solar System | Lex Fridman Podcast #201