Sara Seager: Search for Planets and Life Outside Our Solar System
音乐与艺术生物与进化太空与探索技术与编程物理与宇宙学
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"to detect, like, is there, one, is there scientific evidence and, and second, is there some intuition"
— Sara Seager （23:23.760）
🎙️ 完整对话（1708 条）
Lex Fridman (00:00.000)
The following is a conversation with Sarah Seager, a planetary scientist at MIT known
Lex Fridman (00:06.320)
for her work on the search for exoplanets, which are planets outside of our solar system.
Lex Fridman (00:12.120)
She's an author of two books on this fascinating topic, plus in a couple days, August 18th,
Lex Fridman (00:18.440)
her new book, a memoir called The Smallest Lights in the Universe, is coming out.
Lex Fridman (00:23.680)
I read it and I can recommend it highly, especially if you love space and are a bit of a romantic
Sara Seager (00:29.720)
like me.
Lex Fridman (00:30.720)
It's beautifully written.
Sara Seager (00:32.400)
She weaves the stories of the tragedies and the triumphs of her life with the stories
Sara Seager (00:36.860)
of her love for and research on exoplanets, which represent our hope to find life out
Sara Seager (00:43.440)
there in the universe.
Lex Fridman (00:45.440)
Quick summary of the ads.
Sara Seager (00:46.760)
Three sponsors, Public Goods, that's a new one, PowerDot, and Cash App.
Lex Fridman (00:52.640)
Click the links in the description to get a discount.
Sara Seager (00:55.080)
It really is the best way to support this podcast.
Lex Fridman (00:58.920)
Just a quick side note.
Sara Seager (00:59.920)
Let me say that extraterrestrial life, aliens, I think represent our civilization longing
Sara Seager (01:06.640)
to make contact with the unknown, with others like us, or maybe others that are very different
Sara Seager (01:12.320)
from us, entities that might reveal something profound about why we're here.
Sara Seager (01:18.860)
The possibility of this is both exciting and, at least to me, terrifying, which is exactly
Sara Seager (01:25.080)
where we humans do our best work.
Sara Seager (01:28.480)
If you enjoy this thing, subscribe on YouTube, review it with 5 stars on Apple Podcast, support
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on Patreon, or connect with me on Twitter at Lex Friedman.
Sara Seager (01:37.360)
As usual, I'll do a few minutes of ads now, and never any ads in the middle that could
Sara Seager (01:41.000)
break the flow of the conversation.
Sara Seager (01:43.040)
I try to make these ad reads interesting if you do listen, but if you like, I give you
Sara Seager (01:47.400)
timestamps so you can skip to the conversation, but still, please do check out the sponsors
Lex Fridman (01:53.080)
by clicking the special links in the description.
Sara Seager (01:55.800)
That's the best way to support this podcast.
Sara Seager (01:58.800)
This show is sponsored by Public Goods, the one stop shop for affordable, sustainable,
Sara Seager (02:04.800)
healthy household products.
Sara Seager (02:06.840)
Their products have a minimalist black and white design that I find to be just clean,
Sara Seager (02:11.160)
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Lex Fridman (02:13.160)
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Sara Seager (02:16.360)
I imagine we'll all be using Public Goods products once we colonize Mars.
Sara Seager (02:21.440)
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Sara Seager (02:27.300)
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Lex Fridman (02:33.520)
and supplements.
Sara Seager (02:34.520)
I take their fish oil, for example, which I recommend highly for everyone.
Sara Seager (02:39.060)
They use a membership model to keep costs low and pass on the savings to us, the people.
Sara Seager (02:44.800)
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Lex Fridman (02:50.920)
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Sara Seager (02:53.160)
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Lex Fridman (02:58.920)
order.
Sara Seager (03:00.080)
This show is sponsored by Power Dot.
Sara Seager (03:02.480)
Get it at powerdot.com slash lex and use code lex at checkout to get 20% off and to support
Sara Seager (03:08.720)
this podcast.
Sara Seager (03:10.280)
It's an Eastim electrical stimulation device that I've been using a lot for muscle recovery,
Sara Seager (03:15.960)
mostly for my shoulders and legs as I've been doing the crazy amounts of body weight reps
Lex Fridman (03:20.880)
and 6 miles every other day now after the challenge.
Sara Seager (03:24.200)
Yes, I'm still doing it.
Sara Seager (03:26.540)
They call it the smart muscle stimulator since the app that goes with it is amazing.
Sara Seager (03:31.980)
It has 15 programs for different body parts and guides you through everything you need
Lex Fridman (03:35.360)
to do.
Sara Seager (03:36.360)
I take recovery really seriously these days and Power Dot has been a powerful addition
Lex Fridman (03:41.380)
to stretching, ice, massage, and sleep and diet.
Sara Seager (03:45.960)
It's used by professional athletes and by slightly insane, but mostly normal people
Lex Fridman (03:51.120)
like me.
Sara Seager (03:52.280)
It's portable so you can throw it in a bag and bring it anywhere.
Sara Seager (03:55.560)
Get it at powerdot.com slash lex and use code lex at checkout to get 20% off on top of the
Sara Seager (04:02.240)
30 day free trial and of course to support this podcast.
Sara Seager (04:07.480)
This show is presented by a sponsor that arguably made this whole podcast even possible.
Sara Seager (04:14.400)
Our first sponsor, the great, the powerful Cash App, the number one finance app in the
Lex Fridman (04:19.200)
App Store.
Sara Seager (04:20.200)
I will forever be grateful to them for sponsoring this podcast.
Lex Fridman (04:24.600)
They're awesome people, awesome company, awesome product.
Sara Seager (04:27.800)
Okay, back to the read.
Lex Fridman (04:29.360)
When you get it, use code LEX PODCAST.
Sara Seager (04:32.560)
Cash App lets you send money to friends, buy Bitcoin, and invest in the stock market with
Lex Fridman (04:36.520)
as little as one dollar.
Sara Seager (04:38.580)
Since Cash App allows you to buy Bitcoin, let me mention that cryptocurrency in the
Lex Fridman (04:42.880)
context of the history of money is fascinating.
Sara Seager (04:45.360)
I recommend Ascent of Money as a great book on this history.
Lex Fridman (04:48.840)
Debits and credits on ledgers started around 30,000 years ago.
Sara Seager (04:53.560)
Time flies.
Sara Seager (04:54.560)
The US dollar created over 200 years ago and the first decentralized cryptocurrency released
Sara Seager (04:59.560)
just over 10 years ago.
Lex Fridman (05:01.560)
So given that history, cryptocurrency is still very much in its early days of development,
Lex Fridman (05:06.680)
but it's still aiming to and just might redefine the nature of money.
Lex Fridman (05:11.920)
So again, if you get Cash App from the App Store or Google Play and use code LEX PODCAST,
Sara Seager (05:17.200)
you get $10 and Cash App will also donate $10 to FIRST, an organization that is helping
Lex Fridman (05:22.640)
to advance robotics and STEM education for young people around the world.
Lex Fridman (05:27.520)
And now here's my conversation with Sarah Seeger.
Lex Fridman (05:32.360)
When did you first fall in love with the stars?
Sara Seager (05:34.940)
I think I've always loved the stars.
Lex Fridman (05:37.240)
One of my first memory is of the moon.
Sara Seager (05:39.320)
I remember watching the moon and I was in the car with my dad who my parents were divorced
Lex Fridman (05:44.000)
and he was driving me and my siblings to his house for the weekend and the moon was just
Sara Seager (05:47.920)
following me.
Lex Fridman (05:49.200)
Just had no idea why that was.
Lex Fridman (05:51.400)
So like looking up at the sky and there's this glowing thing, how do you make sense
Lex Fridman (05:55.340)
of the moon at that age?
Sara Seager (05:57.840)
Like age five.
Lex Fridman (05:58.840)
There's just no way you can.
Sara Seager (05:59.840)
I think it's one of the great things about being a kid is just that curiosity that all
Lex Fridman (06:03.640)
kids have.
Sara Seager (06:04.640)
You know, I was thinking because there's these almost out there ideas of that our earth is
Lex Fridman (06:11.160)
flat, floating about on the internet.
Lex Fridman (06:14.440)
And it made me think, you know, when did I first realize that the earth is like this
Lex Fridman (06:21.120)
ball that's flying through empty space?
Sara Seager (06:25.780)
I mean, it's terrifying.
Lex Fridman (06:27.520)
It's awe inspiring.
Sara Seager (06:28.520)
I don't know how to make sense of it.
Lex Fridman (06:31.280)
It's hard because we live in our frame of reference here on this planet.
Sara Seager (06:34.840)
It's nearly impossible.
Lex Fridman (06:35.840)
None of us are lucky to go to see the curvature of earth.
Sara Seager (06:38.240)
I mean, do you remember when you realized, understood like the physics, like the layout
Lex Fridman (06:43.360)
of the solar system?
Sara Seager (06:45.880)
Was it like, did you first have to take physics to really, like high school physics to really
Lex Fridman (06:51.120)
take that in?
Sara Seager (06:52.420)
I think it's hard to say.
Lex Fridman (06:53.480)
I had this book when I was a child.
Sara Seager (06:55.220)
It was in French.
Sara Seager (06:56.220)
I grew up in Canada, where French is supposedly taught to all of us English speaking Canadians.
Lex Fridman (07:01.800)
And it was this book in French was about the solar system, and I just love flipping through
Lex Fridman (07:05.240)
it.
Sara Seager (07:06.240)
It's hard to say how much, you know, you or I understand when we're kids, but it was
Lex Fridman (07:10.120)
really great book.
Lex Fridman (07:11.560)
What about the stars?
Lex Fridman (07:12.560)
When did you first learn about the stars?
Sara Seager (07:14.920)
Like I do have this very incredible distinctive memory.
Lex Fridman (07:17.880)
And again, it had to do with my dad.
Sara Seager (07:19.120)
He took us camping.
Sara Seager (07:20.120)
Now, my dad was from the UK, and he was the type who you'd find wearing a tie on weekends.
Lex Fridman (07:26.040)
So camping was not in his sphere, his comfort zone.
Lex Fridman (07:29.280)
We had a babysitter.
Sara Seager (07:31.680)
Every summer we had a babysitter, and one summer we had Tom.
Lex Fridman (07:34.600)
He was barely older than we were.
Sara Seager (07:36.400)
He was 14.
Lex Fridman (07:37.400)
My brother was 12.
Sara Seager (07:38.400)
I would have been 11 or 10 maybe.
Lex Fridman (07:40.480)
And we went camping because Tom said camping is the thing.
Sara Seager (07:42.920)
We should try it.
Lex Fridman (07:43.920)
And I just remember I didn't aim to see the stars, but I walked out of my tent in the
Sara Seager (07:48.200)
middle of the night, and I looked up, and wow, so many stars.
Lex Fridman (07:55.360)
The dark night sky and all those stars just screaming at me.
Sara Seager (07:59.000)
I just couldn't believe that.
Lex Fridman (08:00.560)
Honestly, my first thought was, this is so incredible, mind blowing.
Lex Fridman (08:04.820)
Why wouldn't anyone have told me this existed?
Lex Fridman (08:07.320)
Can anyone else see this?
Lex Fridman (08:08.880)
Have you had an experience like that with anything?
Lex Fridman (08:12.680)
Yeah.
Sara Seager (08:13.680)
I've had that.
Lex Fridman (08:14.680)
I mean, I don't know if maybe you can tell me if it's the same.
Sara Seager (08:17.560)
I've had that with robots.
Lex Fridman (08:20.000)
There's a few robots I've met where I just fell in love with this.
Lex Fridman (08:23.240)
Is anyone else seeing this?
Sara Seager (08:25.160)
Is anyone else seeing that here in a robot is our ability to engineer some intelligent
Sara Seager (08:34.720)
beings, intelligent beings that we could love, that could love us, that we can interact with
Lex Fridman (08:39.960)
in some rich ways that we haven't yet discovered?
Sara Seager (08:44.440)
Almost like when you get a puppy, instead of a dog, and there's this immediate bond
Lex Fridman (08:49.540)
and love, and on top of that, ability to engineer it, I had to just pause and hold myself.
Sara Seager (08:58.800)
I imagine, I don't have kids, I imagine there's a magic to that as well, where it's a totally
Lex Fridman (09:03.160)
new experience.
Lex Fridman (09:04.160)
It's like, what?
Lex Fridman (09:05.160)
Well, yeah, the stars though, unlike kids or the puppy, it's only a good thing.
Lex Fridman (09:13.520)
So you felt, you weren't terrified?
Sara Seager (09:15.960)
Like to me, when I look at the stars, it's almost paralyzingly scary how little we know
Sara Seager (09:23.420)
about the universe, how alone we are.
Lex Fridman (09:26.200)
I mean, somehow it feels alone.
Sara Seager (09:28.120)
I'm not sure if it's just a matter of perspective, but it feels like, wow, there's billions
Lex Fridman (09:34.800)
of them out there and we know nothing about them.
Lex Fridman (09:39.360)
And then also immediately to me, somehow mortality comes into it.
Lex Fridman (09:42.680)
I mean, how did that make you feel at that time?
Sara Seager (09:45.200)
I think as a child without articulating it, I felt that same way.
Lex Fridman (09:48.880)
Just like, wow, this is terrifying.
Lex Fridman (09:50.600)
What's out there?
Lex Fridman (09:51.600)
Like, what is this?
Lex Fridman (09:52.600)
What does it mean about us here?
Sara Seager (09:55.720)
You're a scientist, an exo world class scientist, planetary scientist, astronomer.
Sara Seager (10:02.200)
Now I'm a bit of an idiot who likes to ask silly questions.
Lex Fridman (10:06.960)
So some questions are a little bit in the realm of speculation, almost philosophical
Sara Seager (10:12.400)
because we know so little and one of the awesome things about your work is you've actually
Sara Seager (10:17.240)
put data and real science behind some of the biggest questions that we're all curious
Sara Seager (10:20.840)
about.
Lex Fridman (10:21.840)
But nevertheless, many of the questions might be a little bit speculative.
Lex Fridman (10:25.640)
So on that topic, just in your sense, do you think we're alone in the universe, human
Lex Fridman (10:33.120)
beings?
Lex Fridman (10:34.120)
Do you think there's life out there?
Sara Seager (10:36.280)
Well, Lex, the funny thing is, is that as a scientist, I so don't even want to answer
Sara Seager (10:40.520)
that.
Sara Seager (10:41.520)
I will answer it though, but I just love to say, yeah, we naturally resist that because
Sara Seager (10:46.160)
we want numbers and hard facts and not speculation.
Lex Fridman (10:49.800)
But I do love that question.
Sara Seager (10:51.200)
It's a great question and it's one we all wonder about, but I have to give you the scientist
Sara Seager (10:55.100)
answer first, which is we'll have the capability to answer that question soon, even starting
Sara Seager (11:01.280)
soon.
Lex Fridman (11:02.280)
How do you define soon?
Lex Fridman (11:03.840)
How do I define soon?
Lex Fridman (11:05.200)
So much happened in the last hundred years.
Sara Seager (11:07.000)
Right, right.
Lex Fridman (11:08.000)
And there's a difference, right, if it's 10 years or 20 years or a hundred years.
Sara Seager (11:11.800)
Yeah, there's a difference in that.
Lex Fridman (11:14.000)
Well, soon could be a decade or two decades.
Sara Seager (11:18.920)
Journalists usually don't like that or the people want like tomorrow, they want the news.
Lex Fridman (11:23.200)
But what it's going to take is telescopes, space telescopes, or very sophisticated ground
Sara Seager (11:28.680)
or space telescopes to let us study the atmospheres of other planets far away and to look what's
Sara Seager (11:35.160)
in the atmospheres and to look for water, which is needed for life as we know it, to
Sara Seager (11:38.640)
look for gases that don't belong that we might attribute to life.
Lex Fridman (11:42.080)
So we have to do some really nitty gritty astronomy.
Lex Fridman (11:45.680)
So the promising way to answer this question scientifically is to look for hints of life.
Sara Seager (11:51.480)
That's where like many of your ideas come in of what kind of hints might we actually
Sara Seager (11:55.960)
see about this life.
Lex Fridman (11:57.200)
Right, right.
Sara Seager (11:58.200)
That's exactly what we need to do.
Lex Fridman (11:59.200)
And I like the word you chose, hint, because it's going to be a hint.
Sara Seager (12:02.600)
It's not going to be a 100% yay, we found it.
Lex Fridman (12:05.600)
And then it will take future generations to do more careful work to hopefully even find
Sara Seager (12:12.200)
a way to send a probe to these distant exoplanets and to really figure this out for us.
Lex Fridman (12:17.640)
I mean, we'll talk about the details.
Sara Seager (12:19.320)
Those are fun, but like the back to the speculation, the zoomed out big picture is, yes, I believe
Lex Fridman (12:26.480)
absolutely there is life out there somewhere.
Sara Seager (12:30.020)
Because the vastness of the universe is incredible.
Lex Fridman (12:33.760)
It's so breathtaking.
Sara Seager (12:35.780)
When we look at the night sky, if you can go to that dark sky, you can see many, many
Sara Seager (12:40.040)
hundred or even if you have good eyesight and you're somewhere very dark, you could
Sara Seager (12:43.480)
see thousands of stars.
Lex Fridman (12:44.880)
But in our galaxy, we have hundreds of billions of stars and our universe has hundreds of
Sara Seager (12:51.240)
billions of galaxies.
Lex Fridman (12:53.820)
So think about all those stars out there.
Lex Fridman (12:57.760)
And even if planets are rare, even if life is rare, just because the number of stars
Lex Fridman (13:02.120)
is so huge, things have to come together somewhere, someplace in our universe.
Sara Seager (13:06.800)
Yeah.
Lex Fridman (13:07.800)
So amazing to think that somebody might be looking up on another planet in a distant
Sara Seager (13:14.120)
galaxy.
Sara Seager (13:15.120)
I have to interrupt your reverie and get back to, in our lifetime at least, the short term.
Sara Seager (13:22.120)
We only have the nearest stars to look at.
Sara Seager (13:24.800)
It's true that there are so many stars, so many hosts for planets that might have life.
Lex Fridman (13:29.480)
But in the practical question of will we find it, it has to be a star quite close to Earth,
Lex Fridman (13:36.080)
like a few light years, tens of light years, maybe hundreds of light years.
Lex Fridman (13:40.080)
And by the way, you've introduced me to a tool of Eyes on Exoplanets, I think that NASA
Lex Fridman (13:46.800)
has put together.
Sara Seager (13:47.800)
Eyes on Exoplanets.
Lex Fridman (13:48.800)
It's a great software.
Sara Seager (13:49.800)
You can download it.
Lex Fridman (13:50.800)
It's so cool.
Lex Fridman (13:51.800)
But anyway, can you give a sense of who our neighbors are?
Lex Fridman (13:56.800)
You said hundreds of light years.
Lex Fridman (14:00.120)
How many stars are close by?
Lex Fridman (14:04.600)
What's our neighborhood like?
Lex Fridman (14:05.600)
Are we talking about five, 10 stars that we might actually have a chance to zoom in on?
Lex Fridman (14:12.640)
I'm talking about maybe a dozen or two dozen stars.
Lex Fridman (14:16.680)
And those with planets that look suitable for us to follow up in detail.
Lex Fridman (14:22.960)
For life.
Sara Seager (14:23.960)
Right.
Lex Fridman (14:24.960)
But one thing that's really exciting in this field is that the very nearest star to Earth
Sara Seager (14:29.920)
called Proxima Centauri, it's part of the Alpha Centauri star system.
Lex Fridman (14:34.240)
Cool name, by the way.
Sara Seager (14:35.240)
Yeah, Proxima.
Lex Fridman (14:36.240)
Whoever names them.
Sara Seager (14:37.240)
Nearby.
Lex Fridman (14:38.240)
Okay, but it sounds cooler than Proxima.
Sara Seager (14:40.520)
Proxima Centauri appears to have a planet around it.
Sara Seager (14:44.120)
It's about an Earth mass planet in the so called habitable zone or the Goldilocks zone
Sara Seager (14:49.560)
of the host star.
Lex Fridman (14:50.560)
So think about how incredible that is.
Sara Seager (14:52.520)
Like out of all the stars out there, even the very nearest star has planets and has
Lex Fridman (14:56.880)
a planet of huge interest to us.
Sara Seager (14:58.880)
Yeah.
Lex Fridman (14:59.880)
Okay.
Lex Fridman (15:00.880)
So can we talk about that planet?
Lex Fridman (15:04.600)
What does it mean to be maybe possibly habitable?
Lex Fridman (15:12.960)
How does size come into play?
Lex Fridman (15:14.960)
How does you know what we know about gases and what kind of things are necessary for
Lex Fridman (15:21.640)
life?
Lex Fridman (15:22.640)
You know, what are the factors that you make you think that it's habitable?
Lex Fridman (15:26.800)
And by the way, I mean, maybe one way to talk about that is people know about the Drake
Sara Seager (15:31.280)
equation, which is a very high level, almost framework to think about what is the probability
Sara Seager (15:39.400)
that, correct me if I'm wrong, that there's life out there and intelligent life, I think.
Lex Fridman (15:46.240)
I don't know.
Lex Fridman (15:47.240)
But then you have a equation named after you now, which I think nicely focuses in on the
Sara Seager (15:54.040)
more achievable and interesting part of that question, which is on whether there is habitable
Sara Seager (16:01.760)
planets out there or how many, I guess.
Lex Fridman (16:04.440)
Right, right.
Lex Fridman (16:05.440)
So the funny thing is, was one time I met Frank Drake and I asked if he minded if I
Sara Seager (16:11.000)
took his equation and kind of revamped it for this new field of exoplanet astronomy.
Sara Seager (16:17.360)
He was totally cool with it.
Lex Fridman (16:18.360)
He's totally cool.
Sara Seager (16:19.360)
He got total approval.
Lex Fridman (16:20.360)
Well, maybe.
Sara Seager (16:21.360)
Okay.
Lex Fridman (16:22.360)
So sorry.
Sara Seager (16:23.360)
I'm not sure if he'd actually read the stuff about my equation, but he was cool with it.
Lex Fridman (16:26.000)
He was cool.
Sara Seager (16:27.000)
He was cool.
Lex Fridman (16:28.000)
Okay.
Lex Fridman (16:29.000)
So I just said like 15 different things, but maybe can you tell from your perspective,
Lex Fridman (16:33.880)
what is the Drake equation and what is, sorry, the Seager equation?
Sara Seager (16:37.400)
Sure.
Lex Fridman (16:38.400)
Well, the Drake equation, as you said, it's a framework.
Sara Seager (16:41.800)
It's a description of the number of civilizations out there of intelligent beings that are able
Lex Fridman (16:48.440)
to communicate with us by radio waves.
Lex Fridman (16:53.040)
So if you think of the movie Contact, you've seen Contact, right?
Lex Fridman (16:58.040)
We're listening in, actually.
Sara Seager (16:59.040)
It's an active field of research, listening to other stars at radio wavelengths, hoping
Lex Fridman (17:03.320)
that some intelligent civilizations are sending us a message.
Lex Fridman (17:07.240)
And the Drake equation came like at the start of that whole field to put the factors down
Lex Fridman (17:12.920)
on paper to sort of illustrate what is involved to kind of estimating.
Lex Fridman (17:18.020)
And there's no real estimate or prediction of how many civilizations are out there, but
Lex Fridman (17:21.520)
it's a way to frame the question and show you each term that's involved.
Lex Fridman (17:25.680)
So I took the Drake equation and I called it a revised Drake equation and I recast it
Lex Fridman (17:32.140)
for the search for planets by more traditional astronomy means.
Sara Seager (17:37.920)
We're looking at stars, looking for planets, looking for rocky planets, looking for planets
Sara Seager (17:42.680)
that are the right temperature for life, looking for planets that might have life that outputs
Sara Seager (17:49.520)
gases that we might detect in the future.
Lex Fridman (17:52.100)
It's the same spirit of the Drake equation.
Sara Seager (17:53.840)
It's not going to give us any magic numbers.
Lex Fridman (17:55.480)
So I'm going to say, hey, here's exactly what's out there.
Sara Seager (17:58.680)
It's meant to kind of guide, guide of where we're going.
Lex Fridman (18:01.360)
So the Drake equation did, I mean the initial equation proposed actual numbers for those
Lex Fridman (18:06.480)
variables, right?
Lex Fridman (18:07.480)
Oh yes.
Sara Seager (18:08.480)
The equation proposed numbers and you can still plug your own numbers in.
Lex Fridman (18:12.240)
And there's this really cute website that lets you for both the Drake and my revised
Sara Seager (18:15.960)
equation plug in some numbers and see what you got.
Lex Fridman (18:19.280)
So yeah.
Sara Seager (18:20.280)
Okay.
Lex Fridman (18:21.280)
So what are, I mean, what are the variables, but maybe also what are like the critical
Lex Fridman (18:24.600)
variables?
Lex Fridman (18:26.320)
So in my equation, I set out to what are the numbers of inhabited planets that show signs
Sara Seager (18:33.640)
of life by way of gases in the atmosphere that can be attributed to life.
Lex Fridman (18:37.520)
I could just walk through the terms as far as I'm aware.
Lex Fridman (18:39.520)
So the first thing I say is what are the number of stars available?
Lex Fridman (18:43.200)
And it's not that those trillions and trillions of stars everywhere.
Sara Seager (18:47.760)
It's what are available to like a specific search.
Lex Fridman (18:51.320)
And so for example, the MIT led NASA mission TESS is surveying the sky, looking for all
Sara Seager (18:57.540)
kinds of planets, but it can also, it also has stars.
Lex Fridman (19:01.600)
It has about 30,000 red dwarf stars.
Lex Fridman (19:04.780)
So we just take a number of stars that a given survey can access.
Lex Fridman (19:08.920)
So that's what the number of stars is.
Sara Seager (19:11.160)
Then I wanted to know what kind of stars are quiet.
Lex Fridman (19:16.000)
I called it fraction of those stars that is quiet.
Sara Seager (19:19.120)
In the case of TESS, the way it's looking for planets is planets that transit the star.
Sara Seager (19:23.680)
They go in front of the star as seen from the telescope, but it turns out that some
Sara Seager (19:27.600)
stars are very active, they're variable and they brighten and dim with time and that interferes
Lex Fridman (19:32.580)
with our observation.
Sara Seager (19:33.580)
I apologize to interrupt.
Lex Fridman (19:35.440)
So it's a transiting planet.
Lex Fridman (19:37.280)
So you're really looking for a black blob, essentially that blocks the light.
Sara Seager (19:42.000)
We're looking for a black blob that blocks the light and then trying to say something
Sara Seager (19:45.560)
about the size of the planet from the frequency of that black blobs appearance and the size
Lex Fridman (19:51.920)
of that black blob, that kind of thing.
Sara Seager (19:53.560)
Yeah.
Lex Fridman (19:54.560)
But let's just say that out of all the stars there are accessible to whatever telescope,
Sara Seager (19:58.560)
some of them are just bad for whatever reason.
Lex Fridman (1:00:02.240)
steps that are required to take, it seems like so daunting, so daunting.
Lex Fridman (1:00:08.420)
So like this, the smart thing seems to be to do the most achievable near daunting task,
Sara Seager (1:00:15.360)
even if there doesn't seem to be a commercial application, which I think is colonizing
Sara Seager (1:00:20.680)
Mars.
Lex Fridman (1:00:21.680)
But like from your perspective, is there some Manhattan project style, huge project in space
Sara Seager (1:00:30.600)
that we might want to take on and you've had roles.
Sara Seager (1:00:34.920)
You had scientists hat roles and then you also had roles in terms of being on like committees
Lex Fridman (1:00:39.600)
and stuff, determining where funding goes and so on.
Lex Fridman (1:00:42.680)
So like, is there a huge like multi trillion, we've been throwing the T word around recently
Lex Fridman (1:00:48.840)
a lot, but these huge projects that we might want to take on?
Sara Seager (1:00:52.200)
Well, first of all, we want to find the planets like earth first, like just even finding those
Sara Seager (1:00:56.220)
earth like planets is a billion dollar endeavor, billions of dollars endeavor.
Lex Fridman (1:01:01.200)
And that's so hard because an earth is so small, so less massive, and so faint compared
Sara Seager (1:01:06.560)
to our sun.
Lex Fridman (1:01:08.100)
It's the proverbial needle in a haystack, but worse.
Lex Fridman (1:01:10.920)
And we need very sophisticated space based telescopes to be able to find these planets
Lex Fridman (1:01:15.560)
and to look, look at them and see which ones have water and which ones have signs of life
Sara Seager (1:01:19.800)
on them.
Sara Seager (1:01:20.800)
Yeah, the, the star shade project that you're part of, star shade, star shade, yeah, this
Sara Seager (1:01:24.720)
is probably the most badass thing I've ever seen.
Lex Fridman (1:01:26.680)
Right.
Lex Fridman (1:01:27.680)
You know what's interesting?
Lex Fridman (1:01:28.680)
Can you describe what it is?
Lex Fridman (1:01:29.680)
So what's amazing about star shade is it was first conceived of in the 1960s.
Sara Seager (1:01:34.920)
Imagine that and revisited every decade until now when we think we can actually build it
Lex Fridman (1:01:38.640)
and star shade is a giant specially shaped screen.
Sara Seager (1:01:42.880)
It is about, there's different versions of it, but think about 30 meters in diameter.
Lex Fridman (1:01:47.120)
So you're blocking out the sun.
Sara Seager (1:01:49.700)
You're effectively blocking out the star so that you can see the planet directly and star
Sara Seager (1:01:54.240)
shade would have a spacecraft attached to it and it would fly in space far away from
Lex Fridman (1:01:58.800)
Earth's gravity and it would have to formation fly with a space telescope.
Lex Fridman (1:02:03.660)
So the idea is that star shade blocks out the starlight in a very careful way and it
Sara Seager (1:02:08.200)
has to block that starlight out so that the planet that is 10 billion times fainter than
Sara Seager (1:02:13.360)
the star, that only the planet light goes to the telescope.
Lex Fridman (1:02:17.640)
Yeah.
Lex Fridman (1:02:19.020)
So in formation, meaning the telescope flies in, you gave a presentation on this, but like
Lex Fridman (1:02:24.840)
it, it would fly like in, um, this is extremely high precision endeavor.
Sara Seager (1:02:30.960)
Yeah.
Sara Seager (1:02:31.960)
We had this analogy like asking a friend to hold up a dime five miles away perfectly.
Sara Seager (1:02:37.040)
Like at the perfect line of sight with you.
Lex Fridman (1:02:40.460)
And the shape of it is pretty cool.
Sara Seager (1:02:41.720)
I mean, uh, I don't know exactly what the physics of that, like what the optics are
Lex Fridman (1:02:45.780)
that require that shape.
Sara Seager (1:02:47.240)
I can tell you, it turns out that if you block out a star, imagine blocking out a star with
Sara Seager (1:02:51.280)
a circle circularly or a square shaped screen, you wouldn't actually be blocking it because
Sara Seager (1:02:57.240)
the star acts like a wave.
Sara Seager (1:02:58.840)
The starlight can act like a wave and it would actually bend around the edges of the screen.
Lex Fridman (1:03:03.840)
And so instead of blocking out the light, you're expecting to see nothing.
Sara Seager (1:03:06.360)
You would see ripples and the analogy that I love to give, it's like throwing a pebble
Sara Seager (1:03:11.120)
in a pond.
Sara Seager (1:03:12.120)
You know, you get those ripples, you get these concentric ripples and they go out and light
Sara Seager (1:03:16.480)
would do something quite similar.
Sara Seager (1:03:18.640)
You'd actually see ripples of light and those ripples of light, they're actually way brighter
Sara Seager (1:03:23.800)
than the planet we'd be looking for.
Lex Fridman (1:03:26.380)
So they would introduce this noise that's a noise.
Lex Fridman (1:03:29.360)
And so the star shade, it's like a mathematical solution to the problem of diffraction it's
Lex Fridman (1:03:33.900)
called.
Lex Fridman (1:03:35.240)
And this is what the first person who thought about star shape in the 1960s worked out the
Lex Fridman (1:03:39.820)
mathematical shape or one salute, one family of solutions.
Lex Fridman (1:03:43.860)
And the idea is that when the star shade, this very special shape, like a giant flower
Sara Seager (1:03:48.320)
with petals, when it blocks out the light, the light bends around the edges, but interacts
Sara Seager (1:03:53.680)
with itself in a way to give you a very, very dark image.
Sara Seager (1:03:57.220)
It would be like throwing a pebble in a pond and instead of getting ripples, the pond would
Sara Seager (1:04:02.240)
be perfectly smooth, like incredibly smooth to one part in 10 billion.
Lex Fridman (1:04:06.760)
And all the waves would be on the outer edges, far away from where you drop that pebble.
Lex Fridman (1:04:11.980)
And so this camera would be able to get some signal from the planet then.
Lex Fridman (1:04:19.640)
Yes, and it would be hard because the planet is so faint.
Lex Fridman (1:04:22.020)
But with the star out of the way, the glare of that bright, bright, bright star, with
Lex Fridman (1:04:25.840)
that out of the way, then it becomes a much more manageable task.
Lex Fridman (1:04:30.500)
So how do we get that thing out there?
Lex Fridman (1:04:32.520)
We're working with unlimited money.
Sara Seager (1:04:34.040)
Okay, we're working with unlimited money.
Lex Fridman (1:04:35.800)
We have some more engineering problems to solve, but not too many more.
Sara Seager (1:04:39.160)
We've been burning down our so called tall pole list.
Lex Fridman (1:04:43.000)
What kind of list?
Sara Seager (1:04:44.000)
We call it technology tall pole.
Sara Seager (1:04:47.360)
It's the phrase where you have to figure out what are your hardest problems and then break
Sara Seager (1:04:51.860)
those down to solve.
Lex Fridman (1:04:53.080)
So the star shade, one of the really hard problems was how to formation fly at tens
Sara Seager (1:04:57.760)
of thousands of kilometers.
Lex Fridman (1:04:59.800)
It's like, wow, that is insane.
Lex Fridman (1:05:02.120)
And the team broke that down actually into a sensing problem because of the star shade.
Lex Fridman (1:05:06.760)
How do you see the star shade precisely enough to control it?
Sara Seager (1:05:10.200)
Because if you're shining a flashlight, you know the beam spreads out.
Lex Fridman (1:05:13.720)
So the star shade has a beacon, an LED or a laser, it's going to spread out so much
Sara Seager (1:05:17.800)
by the time it gets to the telescope.
Sara Seager (1:05:19.940)
The problem wasn't how do you tell the star shade how to move around fast enough to stay
Sara Seager (1:05:23.240)
in a straight line.
Lex Fridman (1:05:24.560)
The problem was how are you able to sense it well enough?
Lex Fridman (1:05:27.720)
So problems like that were broken down and money that came from NASA to solve problems
Lex Fridman (1:05:32.540)
is put towards solving it.
Lex Fridman (1:05:34.460)
So we've got through most of the hard problems right now.
Sara Seager (1:05:37.020)
Another one was that star shade, even though it's looking at a star, light from our own
Sara Seager (1:05:41.500)
sun could hit the edges of the star shade and bounce off into the telescope, believe
Lex Fridman (1:05:46.880)
it or not.
Lex Fridman (1:05:48.720)
And that would actually ruin it because we're trying to see this tiny, tiny signal.
Lex Fridman (1:05:52.960)
So then the question is how do you make a razor thin edge?
Sara Seager (1:05:55.760)
Those pedal edges would have to be like a razor.
Lex Fridman (1:05:58.640)
What materials can you use?
Lex Fridman (1:05:59.640)
So there's a series of problems like that.
Lex Fridman (1:06:01.640)
Wow.
Lex Fridman (1:06:02.640)
So there's a materials problem in there?
Lex Fridman (1:06:03.880)
Some of them.
Sara Seager (1:06:04.880)
Mm hmm.
Lex Fridman (1:06:05.880)
Wow.
Lex Fridman (1:06:06.880)
And there's one.
Lex Fridman (1:06:07.880)
So we almost finished solving all those problems and then it's just a matter of building one
Lex Fridman (1:06:12.820)
and testing it in a full scale size facility and then building the telescope.
Sara Seager (1:06:18.060)
It's just a matter of time to build everything and get it, get it up for launch.
Lex Fridman (1:06:22.220)
So this is an engineering close engineering project.
Lex Fridman (1:06:26.520)
It's a real engineering project.
Sara Seager (1:06:28.240)
I actually can tell you about two other projects that are not mine.
Sara Seager (1:06:32.320)
I like to call, call star shade mine because it was my project that I helped make it mainstream
Sara Seager (1:06:38.900)
without line is constantly shifting.
Sara Seager (1:06:40.840)
When I started, when I got this leadership role on star shade, I remember telling people
Sara Seager (1:06:44.480)
about it and it was definitely not on the mainstream okay line.
Sara Seager (1:06:47.860)
It was on the giggle factor side of the line and people would just laugh like that's dead.
Lex Fridman (1:06:52.420)
Like you can never formation fly or they'd say, why are you working on that?
Lex Fridman (1:06:55.800)
That's just so not, it's not so awesome.
Sara Seager (1:06:58.280)
There's a, there's a few things you've done in your life and that's when I first saw star
Lex Fridman (1:07:01.820)
shade, I was like, what, really?
Lex Fridman (1:07:04.700)
And then like it sinks in.
Sara Seager (1:07:07.060)
I mean, it's the same thing I felt with like Elon Musk or certain people who do crazy stuff
Lex Fridman (1:07:11.940)
and like, and then, and they get, they actually make it work.
Sara Seager (1:07:15.820)
I mean, if you get star shade information flying to like together, I mean, how awesome
Sara Seager (1:07:22.860)
is that if you actually make that happen, even like from a robot, I'm sorry, from the
Sara Seager (1:07:27.520)
robotics perspective, even if it doesn't give us good data, that's just like a cool
Sara Seager (1:07:31.600)
thing to get out there.
Lex Fridman (1:07:33.180)
I mean, it's really exciting.
Sara Seager (1:07:34.600)
Really cool.
Lex Fridman (1:07:35.600)
So there's two other topics that aren't mine, but I still love them.
Sara Seager (1:07:39.340)
One of them, let's just talk about it briefly because it's not a probe, but it's the idea
Lex Fridman (1:07:43.160)
to send a telescope very far away to 500 times the earth sun distance.
Lex Fridman (1:07:47.820)
And this is way farther than the Voyager spacecrafts are right now.
Lex Fridman (1:07:51.160)
And to use our sun as a gravitational lens, to use our sun to magnify something that's
Sara Seager (1:07:56.740)
behind it.
Lex Fridman (1:07:59.200)
It's got to sink in for a minute.
Sara Seager (1:08:00.980)
Exactly.
Lex Fridman (1:08:01.980)
But I mean, I don't know what the physics of that is, like how to use the sun.
Sara Seager (1:08:05.400)
In astronomy, and Einstein thought about this initially, we can use a massive objects, bend
Lex Fridman (1:08:11.000)
space.
Lex Fridman (1:08:12.120)
And so light that should be traveling like straight, it actually travels around the warped
Lex Fridman (1:08:16.900)
space.
Lex Fridman (1:08:18.440)
And somehow you figure out a way to use that for magnification.
Lex Fridman (1:08:23.060)
You have a way to use that for magnification.
Sara Seager (1:08:25.220)
That's right.
Sara Seager (1:08:26.220)
There are galaxies that are lensed, so called gravitational lens by intervening galaxy clusters
Sara Seager (1:08:33.060)
actually.
Lex Fridman (1:08:34.660)
And there are microlensing events where stars get magnified as an unseen gravitational lens
Sara Seager (1:08:40.740)
star passes in between us and that very distant star.
Lex Fridman (1:08:43.600)
It's actually a real tool in astronomy.
Sara Seager (1:08:45.540)
Yeah, using gravitational lensing to magnify because it bends more rays towards you than
Lex Fridman (1:08:49.940)
normally you'd normally see.
Lex Fridman (1:08:52.060)
And again, we're trying to get more higher resolution images that are basically boiled
Lex Fridman (1:08:58.740)
down to light.
Sara Seager (1:08:59.740)
Well, it boils down to light.
Lex Fridman (1:09:01.700)
And then you can maybe get more information about.
Sara Seager (1:09:04.780)
Well, in this case, you would ask me, let's say, if this thing could get built, it would
Sara Seager (1:09:10.500)
take like something like they like to say 25 years to get from here to there, 25 years
Lex Fridman (1:09:15.780)
and then it could send some information back to us.
Lex Fridman (1:09:18.300)
And then you'd say, so Sarah, how many pixels?
Lex Fridman (1:09:20.540)
And I wouldn't say one or less than one.
Sara Seager (1:09:21.900)
I'd say, you know, it could be like 10 by 10 pixels, it could be 100 pixels, which would
Sara Seager (1:09:26.300)
be awesome.
Lex Fridman (1:09:27.300)
I mean, that's still crazy that we can get a lot of information from that.
Sara Seager (1:09:30.500)
Crazy, right.
Lex Fridman (1:09:31.500)
And it's crazy for a lot of other reasons, because again, you have to line up the sun
Lex Fridman (1:09:34.340)
and your target.
Sara Seager (1:09:35.340)
You'd only have one telescope per target, because every star is behind the sun in a
Sara Seager (1:09:39.980)
different way.
Lex Fridman (1:09:42.460)
So it's a lot of complicated things.
Lex Fridman (1:09:43.980)
What about the second?
Lex Fridman (1:09:44.980)
The second one, it's called star shot.
Sara Seager (1:09:48.580)
You know, star shot means like big dreams and it's an initiative by the Breakthrough
Lex Fridman (1:09:53.540)
Foundation.
Lex Fridman (1:09:55.740)
And star shot is the concept to send thousands of little tiny spacecraft, which they now
Lex Fridman (1:10:02.700)
call star chip.
Lex Fridman (1:10:03.700)
So instead of star ship, it's star chip.
Lex Fridman (1:10:06.580)
And there's a little chip and the star chip, so like sending like thousands of little turtles
Sara Seager (1:10:13.520)
being born, they're not all going to make it.
Sara Seager (1:10:15.100)
The idea is to send lots of them, and each of these star chips, once they're launched
Sara Seager (1:10:20.700)
into, I guess, low Earth orbit, they will deploy a solar sail that's a few meters in
Lex Fridman (1:10:26.420)
diameter.
Lex Fridman (1:10:27.940)
And the idea is that on Earth, we would have a bank of, this one is still a bit on the
Sara Seager (1:10:34.040)
other side of the line, but we'd have a bank of telescopes with lasers that would be like
Sara Seager (1:10:40.420)
a gigawatt power and these lasers would momentarily shine upwards and accelerate, they'd hit these
Lex Fridman (1:10:48.660)
sails.
Sara Seager (1:10:49.660)
They'd be like a power source for the sail and would accelerate the sails to travel at
Lex Fridman (1:10:54.500)
about a 20th the speed of light.
Lex Fridman (1:10:57.700)
Is that as crazy as it sounds?
Sara Seager (1:10:59.940)
Well, like any good engineering project, it has to be broken down into the crazy parts.
Lex Fridman (1:11:05.720)
And the Breakthrough Initiative, like to their huge credit, is sponsoring, you know, getting
Sara Seager (1:11:11.500)
over these, actually, they've listed initially, they listed 19 challenges, so it's broken
Sara Seager (1:11:16.260)
down to concrete things.
Sara Seager (1:11:17.940)
Like one of them is, well, you have to buy the land and make sure the airspace is okay
Sara Seager (1:11:21.340)
with you sending up that much power overhead.
Sara Seager (1:11:24.980)
Another one is you have to have material on the sail where the lasers won't just vaporize
Sara Seager (1:11:29.100)
it.
Lex Fridman (1:11:30.100)
So there's a lot of issues, but anyway, these sails would be accelerated to 20th the speed
Sara Seager (1:11:33.580)
of light and their journey to the nearest star would no longer be tens of thousands
Sara Seager (1:11:38.460)
of years, but could be 20 years, okay, 20, so it's not as bad as tens of thousands.
Lex Fridman (1:11:45.860)
And these thousands or whatever, however many make it, they'll go by the nearest star system
Lex Fridman (1:11:52.060)
and snap some images and radio the information back to Earth because they're traveling so
Sara Seager (1:11:57.220)
fast they can't slow down, but they'll zoom by, take some photos, send it back.
Lex Fridman (1:12:01.340)
Hi, Rez.
Sara Seager (1:12:02.340)
See, just what I want you to pause on for a second is that just by making that a real
Sara Seager (1:12:06.180)
concept and the money given won't make it happen, but what it's done is it's planted
Sara Seager (1:12:11.220)
the seed and it's shifted that line from what is crazy to what is a real project.
Sara Seager (1:12:15.980)
It's shifted it just ever so slightly enough, I think, to plant the seed that we have to
Sara Seager (1:12:20.020)
find a way to somehow find a way to get there.
Lex Fridman (1:12:23.300)
That is, again, to stay on that, that is so powerful.
Sara Seager (1:12:26.380)
Make a big, crazy idea and break it down into smaller, crazy ideas, order it in a list,
Lex Fridman (1:12:34.620)
and knock it out one at a time.
Sara Seager (1:12:38.820)
I don't know, I've never heard anything more inspiring from an engineering perspective
Lex Fridman (1:12:43.260)
because that's how you solve the impossible things.
Lex Fridman (1:12:46.060)
So you open your new book discussing Rogue Planet, PSO, J318, I never said this out loud,
Sara Seager (1:12:55.300)
PSO 1.522, so a Rogue Planet, which is just this poetic, beautiful vision of a planet
Sara Seager (1:13:03.180)
that, as you write, lurches across the galaxy like a rudderless ship wrapped in perpetual
Sara Seager (1:13:10.780)
darkness, its surface swept by constant storms, its black skies raining molten iron.
Sara Seager (1:13:18.500)
Just like the vision of that, the scary, the darkness, just how not pleasant it is for
Lex Fridman (1:13:27.340)
human life, just the intensity of that metaphor, I don't know.
Lex Fridman (1:13:32.900)
And the reason you use that is to paint in a feeling of loneliness, I think, and despair.
Lex Fridman (1:13:43.700)
And why, maybe on the planet side, why does it feel, maybe it's just me, why does it feel
Lex Fridman (1:13:53.860)
so profoundly lonely on that kind of planet?
Lex Fridman (1:13:57.860)
Like what...
Sara Seager (1:13:59.420)
I think it's because we all want to be a part of something, a part of a family, or a part
Lex Fridman (1:14:06.260)
of a community, or a part of something.
Lex Fridman (1:14:10.540)
And so, our solar system, and by the way, I only, it's sort of like when you treat yourself
Sara Seager (1:14:16.980)
to like eating an entire tub of ice cream, like I sometimes treat myself to imagine things
Sara Seager (1:14:21.980)
like this and not just be so cut and dried.
Lex Fridman (1:14:25.140)
But when you imagine that, this planet's not part, because I don't want to give emotions
Sara Seager (1:14:28.380)
to a planet per se, but the planet's not part of anything.
Sara Seager (1:14:31.460)
It's somehow, it's just all on its own, just kind of out there without that warm energy
Sara Seager (1:14:37.140)
from its sun, it's just all alone out there.
Sara Seager (1:14:40.980)
To me, it was this little discovery that I actually feel pretty good being part of this
Sara Seager (1:14:45.980)
solar system.
Sara Seager (1:14:47.580)
It felt like we have a sun, we have like a little family, and it felt like it sucked
Sara Seager (1:14:52.540)
for the rogue planet to just floating about, not floating, flying rudderless.
Lex Fridman (1:14:59.900)
By the way, how many rogue planets are there in your sense?
Sara Seager (1:15:04.620)
We don't know totally.
Lex Fridman (1:15:05.620)
I mean, there's some rogue planets that are just born on their own.
Lex Fridman (1:15:08.540)
I know that sounds really weird to be, how can you be born an orphan?
Lex Fridman (1:15:11.900)
But they just are, because most planets are born out of a disc of gas and dust around
Sara Seager (1:15:17.660)
a star.
Lex Fridman (1:15:18.660)
But some of these small planets are like totally failed stars.
Sara Seager (1:15:21.580)
They're so failed, they're just small planets on their own.
Lex Fridman (1:15:24.580)
But we think that there's probably, honestly, there's another path to a rogue planet.
Sara Seager (1:15:29.060)
That's one that's been kicked out of its star system by other planets, like a game of billiard
Lex Fridman (1:15:33.060)
balls.
Sara Seager (1:15:34.060)
It just gets kicked out.
Lex Fridman (1:15:35.660)
We actually think there's probably as many rogue planets as stars.
Sara Seager (1:15:39.780)
No flying out there, fundamentally alone.
Lex Fridman (1:15:44.620)
So the book is a memoir, is about your life, and it weaves both your fascination with planets
Sara Seager (1:15:56.740)
outside the solar system and the path of your life, and you lost your husband, which is
Lex Fridman (1:16:05.780)
a kind of central part of the book that created a feeling of the rogue planet.
Lex Fridman (1:16:15.620)
By the way, what's the name of the book?
Lex Fridman (1:16:17.380)
The name of the book is The Smallest Lights in the Universe.
Lex Fridman (1:16:21.740)
What's up with the title?
Lex Fridman (1:16:22.740)
What's the meaning?
Sara Seager (1:16:23.740)
The title has a double meaning.
Lex Fridman (1:16:25.100)
On the face of it, it's the search for other Earths.
Sara Seager (1:16:27.700)
Earths are so dim compared to the big, bright, massive star beside them.
Sara Seager (1:16:32.900)
Searching for the Earths is like searching for the smallest lights in the universe.
Sara Seager (1:16:38.700)
It has this other meaning, too.
Sara Seager (1:16:42.300)
I really hope that you or the other people listening never get to the place where you've
Sara Seager (1:16:49.060)
fallen off the cliff into this horrible place of huge despair.
Lex Fridman (1:16:56.500)
And once in a while, you get a glimmer of a better life, of some kind of hope.
Lex Fridman (1:17:01.060)
And those are also the smallest lights in the universe.
Sara Seager (1:17:03.420)
Well, maybe we can tell the full story before we talk about the glimmer of hope.
Lex Fridman (1:17:11.720)
What did it feel like to first find out that your husband, Mike, was sick?
Lex Fridman (1:17:17.620)
It was incredibly frustrating.
Sara Seager (1:17:19.540)
Like, lots of us have had some kind of problem that the doctors completely ignore.
Lex Fridman (1:17:25.100)
Just that they kept blowing him off.
Sara Seager (1:17:27.340)
It's nothing.
Lex Fridman (1:17:28.340)
Are they paid to just say it's nothing?
Sara Seager (1:17:30.740)
I mean, it's just insane.
Lex Fridman (1:17:32.060)
I was just so angry.
Lex Fridman (1:17:34.580)
And we finally got to a point where he was really sick.
Lex Fridman (1:17:37.140)
He was like in bed, not able to move, basically.
Lex Fridman (1:17:41.680)
And it turned out all the things they ignored and not done any tests, he had like a 100%
Lex Fridman (1:17:47.460)
blockage in his intestine.
Sara Seager (1:17:48.940)
Like 100%.
Lex Fridman (1:17:49.940)
Like nothing could get out, nothing could get in.
Lex Fridman (1:17:53.900)
And it was pretty, pretty shocking to even hear then that it could be nothing.
Lex Fridman (1:17:58.580)
What was the progression of it in the context of the maybe the medical system, the doctors?
Lex Fridman (1:18:03.140)
I mean, what did it feel like?
Lex Fridman (1:18:05.340)
Did you feel like a human being?
Sara Seager (1:18:08.940)
I felt like a child.
Sara Seager (1:18:11.180)
Like the doctors were trying to water down the real diagnosis or treat us like we couldn't
Sara Seager (1:18:19.260)
know the truth or they didn't know.
Sara Seager (1:18:21.060)
You know, I felt mixed like, it's not a good situation if you think the doctor either has
Sara Seager (1:18:24.920)
no idea what he or she is doing, or if the doctors purposely, let's just say lying to
Lex Fridman (1:18:29.780)
you to sugarcoat it.
Sara Seager (1:18:30.780)
Like, I didn't know which one of it was, but I knew it was one of those.
Lex Fridman (1:18:34.140)
What were the things he was suffering from?
Sara Seager (1:18:37.660)
Well, initially, he just had a random stomach ache.
Sara Seager (1:18:39.860)
I hate to say that out loud because I know a lot of people will have a random stomach
Sara Seager (1:18:43.380)
ache.
Lex Fridman (1:18:44.380)
But so he just had a bad stomach ache and then, hmm, this is weird.
Sara Seager (1:18:47.420)
A few days later, another bad stomach ache, kind of gets worse.
Lex Fridman (1:18:50.420)
Might go away for a few weeks, might come back.
Lex Fridman (1:18:52.940)
And at the time, all I knew was my dad had had that same thing.
Sara Seager (1:18:56.700)
Not the same identical system, but he had these really weird pains and he ended up having
Sara Seager (1:19:01.820)
the worst diagnosis.
Sara Seager (1:19:03.620)
One of the worst diagnoses you can get from a random stomach ache is pancreatic cancer
Sara Seager (1:19:07.900)
because the time, the pancreas, like you can't feel anything, so by the time you feel pain,
Lex Fridman (1:19:12.380)
it's too late.
Sara Seager (1:19:13.380)
It's spread already.
Lex Fridman (1:19:14.380)
So I was just like, beside myself, I'm like, this is like, wow, this guy, he's got a random
Sara Seager (1:19:19.220)
stomach ache.
Sara Seager (1:19:20.220)
All I know is another man I loved had a random stomach ache and it didn't end well.
Lex Fridman (1:19:24.100)
How did you deal with it emotionally, psychologically, intellectually, as a scientist?
Lex Fridman (1:19:30.380)
What was that like, that whole, because it's not immediate.
Sara Seager (1:19:34.060)
It's a long journey.
Lex Fridman (1:19:35.060)
It's a long journey and you don't know where the diagnosis is going.
Lex Fridman (1:19:38.960)
So anyone who's suffered from a major illness, there's like always branches in the road.
Lex Fridman (1:19:44.120)
So he had this intestinal blockage.
Sara Seager (1:19:47.140)
I can't imagine someone in their 40s having that and that be normal.
Lex Fridman (1:19:50.660)
But the doctor is like, it could be nothing, could just cut it out.
Sara Seager (1:19:54.540)
You don't need most of your intestine, it's a repeating pattern.
Lex Fridman (1:19:56.740)
Just cut that out, it could be fine.
Lex Fridman (1:19:57.900)
But it ended up not being fine and he was diagnosed as being terminally ill.
Lex Fridman (1:20:01.300)
Well, it really changed my life in a huge way.
Sara Seager (1:20:04.060)
First of all, I remember immediately one summer, the summer when this happened, I started asking
Lex Fridman (1:20:09.780)
everyone I knew.
Sara Seager (1:20:10.780)
I would ask you, I don't know if it's smart of my job to put you on the spot, I'd say,
Sara Seager (1:20:15.300)
you have one year to live or two or three, what will you do differently about your life
Lex Fridman (1:20:19.620)
now?
Lex Fridman (1:20:20.620)
Lex, you have one year to live, what would you do?
Sara Seager (1:20:26.580)
I mean, it's hard.
Lex Fridman (1:20:27.580)
I don't know if you want to answer that.
Sara Seager (1:20:28.580)
No, no, no.
Lex Fridman (1:20:29.580)
I think about it a lot.
Sara Seager (1:20:30.580)
I mean, that's a really good thing to meditate on.
Sara Seager (1:20:33.540)
We can talk about maybe why you bring that up, if it is or not a heavy question.
Lex Fridman (1:20:41.300)
But I get, I think about mortality a lot and for me, it feels like a really good way to
Sara Seager (1:20:52.820)
focus in on is what you're doing today, the people you have around you, the family you
Lex Fridman (1:20:57.820)
have, does it bring you joy?
Lex Fridman (1:21:04.020)
Does it bring you fulfillment?
Lex Fridman (1:21:07.180)
And basically, for me, long ago, try to be ready to die any day.
Lex Fridman (1:21:19.460)
So like today, I kind of woke up, look, if I was nervous about talking to you, I really
Sara Seager (1:21:27.340)
admire your work and the book is very good and it's super exciting topic.
Lex Fridman (1:21:33.580)
But then, you know, there's this also feeling like, if this is the last conversation I have
Sara Seager (1:21:37.780)
in my life, you know, if I die today, will this be, will this be the right, like am I
Lex Fridman (1:21:43.580)
glad today happened and it is, and I am glad today happened.
Lex Fridman (1:21:48.620)
So that's the way.
Lex Fridman (1:21:49.620)
And that's so unique.
Sara Seager (1:21:50.620)
I never got that answer from a single person.
Sara Seager (1:21:54.620)
The busyness of life, there's goals, there's dreams, there's like planning, plans.
Sara Seager (1:22:00.340)
Very few people make it happen.
Lex Fridman (1:22:02.860)
That's what I learned.
Lex Fridman (1:22:04.280)
And so a lot of these people.
Lex Fridman (1:22:05.280)
Oh, like you run out of time.
Sara Seager (1:22:07.380)
It's not so much you run out of time, but I'd come back later and be like, okay, why
Lex Fridman (1:22:09.860)
don't you do that?
Lex Fridman (1:22:10.860)
And if that's what you would do, if you're going to die a year from now, why don't you,
Lex Fridman (1:22:14.340)
why don't you make it real?
Sara Seager (1:22:16.640)
Simple things.
Lex Fridman (1:22:17.640)
Spend more time with family.
Sara Seager (1:22:18.640)
Yeah.
Lex Fridman (1:22:19.640)
Like why, why don't you do that?
Lex Fridman (1:22:20.640)
And that's what I had an answer, it turns out, unless you usually, unless you have,
Sara Seager (1:22:24.640)
you really do have a pressing end of life, people don't do their bucket lists or try
Sara Seager (1:22:29.120)
to change their career.
Lex Fridman (1:22:30.360)
And some people can't.
Lex Fridman (1:22:31.360)
So we can't, like for a lot of people, they can't do anything about it.
Lex Fridman (1:22:33.900)
And that's, that's fine.
Lex Fridman (1:22:34.900)
But the ones who can take action for some reason, never do.
Lex Fridman (1:22:38.100)
And that was one of the ways that Mike's death or at the time his impending death really,
Sara Seager (1:22:44.140)
really affected me.
Sara Seager (1:22:45.140)
Cause you know, for these sick people, what I learned, he had a bucket list and he was
Sara Seager (1:22:48.980)
able to do some of the bucket lists.
Lex Fridman (1:22:50.300)
It was awesome.
Lex Fridman (1:22:51.980)
But he got sick pretty quickly.
Lex Fridman (1:22:54.320)
So if you do only have a year to live, it's ironic cause you can't do, you can't do the
Sara Seager (1:22:58.240)
things you wanted to do because you get too sick too fast.
Lex Fridman (1:23:01.420)
What were the bucket list things for you that you realized like, what am I doing with my
Lex Fridman (1:23:05.980)
life?
Lex Fridman (1:23:06.980)
That was the major concept of him.
Sara Seager (1:23:08.540)
After he died, I didn't know.
Sara Seager (1:23:09.860)
Like I, I was just lost because when something that profound happens, all the things I was
Sara Seager (1:23:16.040)
doing, most of the things I was doing were just meaningless.
Lex Fridman (1:23:20.020)
It was so tough to, to find an answer for that.
Lex Fridman (1:23:23.940)
And that's when I settled on, I'm going to devote the rest of my life to trying to find
Lex Fridman (1:23:28.780)
another earth and to find out, to find that we're not alone.
Lex Fridman (1:23:37.420)
What is that longing for connection with others?
Lex Fridman (1:23:42.100)
What's that about?
Lex Fridman (1:23:43.100)
What do you think?
Lex Fridman (1:23:44.100)
Why is that so full of meaning?
Sara Seager (1:23:45.460)
I don't know why.
Lex Fridman (1:23:46.460)
I mean, I think it's how we're hardwired.
Sara Seager (1:23:48.300)
Like one of my friends some time ago, actually when my dad died, he never heard someone say
Lex Fridman (1:23:54.120)
this before, but he's like, Sarah, you know, why are we evolved to take death so harshly?
Lex Fridman (1:24:01.860)
Like what kind of society would we be if we just didn't care people died?
Lex Fridman (1:24:05.860)
That would be a very different type of world.
Lex Fridman (1:24:07.300)
How would we as a species have got to where we are?
Lex Fridman (1:24:11.560)
So I think that is tied hand in hand with why do we, why do we seek connection?
Sara Seager (1:24:16.140)
It's just that what we were talking about before, that subconsciousness that we don't
Lex Fridman (1:24:20.060)
understand.
Sara Seager (1:24:21.060)
Yeah.
Sara Seager (1:24:22.060)
A couple, you know, the other side, the flip side of the coin of connection and love is
Sara Seager (1:24:28.620)
a fear of loss.
Sara Seager (1:24:31.000)
It's like that was, again, I don't know, that's what makes you appreciate the moment is that
Sara Seager (1:24:36.700)
the thing ends.
Lex Fridman (1:24:37.700)
Yeah.
Sara Seager (1:24:38.700)
It's definitely a hard one.
Lex Fridman (1:24:40.020)
The thing ends, but, and it's hard to not, you wouldn't want to limit.
Sara Seager (1:24:45.300)
Like it's like my dog who I love so much, I'll start to cry.
Lex Fridman (1:24:49.220)
Like I can't think about the end.
Sara Seager (1:24:50.420)
I know he'll age much faster than I will.
Lex Fridman (1:24:52.740)
And someday it will end.
Sara Seager (1:24:53.740)
Right.
Lex Fridman (1:24:54.740)
But it's too sad to think of, but should I not have got a dog?
Sara Seager (1:24:57.420)
Right.
Sara Seager (1:24:58.420)
Should I have not brought this sort of joy into my life because I know it won't be forever.
Sara Seager (1:25:02.380)
It's
Sara Seager (1:25:03.380)
well, there's a, there's a philosopher and his Becker who wrote a book, Denial of Death
Lex Fridman (1:25:08.940)
and just, and warm with the cores.
Lex Fridman (1:25:11.780)
And there's another book talks about terror management theory, Sheldon Solomon.
Sara Seager (1:25:16.020)
I just talked to him a few weeks ago.
Sara Seager (1:25:18.820)
It's a brilliant philosopher, psychologist that their theory, whatever you make of it
Sara Seager (1:25:24.900)
is that the fear of death is at the core of everything, everything we do.
Lex Fridman (1:25:32.060)
So like you're that you think you don't think about the mortality of your dog, but you do.
Lex Fridman (1:25:40.180)
And that's what makes the experience rich.
Sara Seager (1:25:42.340)
Like there's this kind of like in the shadows lurks the, the knowledge that this won't
Sara Seager (1:25:49.900)
last forever.
Lex Fridman (1:25:51.500)
And that makes every moment just special in some kind of a weird way that the moments
Sara Seager (1:25:58.740)
are special for us humans.
Sara Seager (1:26:01.100)
I mean, sorry to use romantic terms like love, but what do you make, what did you learn about
Lex Fridman (1:26:12.500)
love from, from losing it, from losing your husband?
Lex Fridman (1:26:18.820)
Well I learned to love the things I have more.
Sara Seager (1:26:21.980)
I learned to love the people that I have more and to not let the little things bother me
Lex Fridman (1:26:28.740)
as much.
Lex Fridman (1:26:30.780)
What about the rediscovery or like the discovery of the little lights in the darkness?
Lex Fridman (1:26:41.700)
So you, the book, I think you've brilliantly described the dark parts of your journey.
Lex Fridman (1:26:52.500)
But maybe can you talk about how you were able to rediscover the lights?
Lex Fridman (1:27:00.420)
They came in many ways.
Lex Fridman (1:27:02.340)
And the way like to think about it is like grief is an ocean, you know, with tiny islands
Lex Fridman (1:27:09.040)
of the little, like, like the little lights.
Lex Fridman (1:27:10.980)
And eventually that ocean gets smaller and smaller and the islands like become continents
Lex Fridman (1:27:15.380)
with lakes.
Lex Fridman (1:27:17.180)
So initially it'd be like the children laughing one day or my colleagues at work who rallied
Lex Fridman (1:27:22.320)
around me and would take me away from my darkness to work on a project.
Sara Seager (1:27:28.580)
Later on it turned out to be a group of women my age, all widows, all with children in my
Lex Fridman (1:27:33.580)
town.
Lex Fridman (1:27:35.360)
And it would be, even though it was a bit morose getting together, still very joyful
Lex Fridman (1:27:40.060)
at the same time.
Lex Fridman (1:27:42.420)
What was the journey of rediscovering love like for you?
Lex Fridman (1:27:47.260)
So refinding, I mean, is there some, by way of advice or insight about how to, how to
Lex Fridman (1:27:57.940)
rediscover the beauty of life?
Lex Fridman (1:28:00.300)
Of life.
Sara Seager (1:28:01.300)
It's a hard one.
Lex Fridman (1:28:02.300)
I think you just have to stay open to being positive and just to get out there.
Lex Fridman (1:28:09.820)
Do you still think, do you still think about your own mortality?
Lex Fridman (1:28:13.180)
So you mentioned that that was a thing that you meditate on as a question when it was
Sara Seager (1:28:19.960)
right there in front of you.
Lex Fridman (1:28:22.420)
But do you still think about it?
Sara Seager (1:28:23.980)
I think I will after talking to you.
Lex Fridman (1:28:26.260)
But no, it's not really something I think about.
Lex Fridman (1:28:28.660)
I mean, I do think about the search for another earth and will, will I get there?
Lex Fridman (1:28:33.660)
Will I be able to conclude my search and is there one?
Sara Seager (1:28:38.860)
Like as time goes by, you know, that window to solve that problem gets smaller.
Lex Fridman (1:28:45.380)
What would bring you, again, I apologize if this makes concrete the fact that life is
Lex Fridman (1:28:51.500)
finite, but what, what would bring you joy if we discovered while you're still here?
Lex Fridman (1:28:58.020)
What would bring me joy?
Sara Seager (1:28:59.380)
Finding another earth, an earth like planet around a sun like star, knowing that there's
Sara Seager (1:29:04.280)
at least one or more out there, being able to see water, that it has signs of water and
Sara Seager (1:29:09.860)
being able to see some gases that don't belong.
Lex Fridman (1:29:12.480)
So I know that the search will continue after I'm gone enough to fuel the next generation.
Lex Fridman (1:29:18.500)
So just like opening the door and there's like this glimmer of hope.
Lex Fridman (1:29:24.140)
What do you think it will take to realize that?
Sara Seager (1:29:25.820)
I mean, we've talked about all these interesting projects, star shade, especially, but is there
Sara Seager (1:29:29.760)
something that you're particularly kind of hopeful about in the next 10, 20 years that
Lex Fridman (1:29:36.480)
might give us that, that exact glimmer of hope that there's earth like planets out there?
Sara Seager (1:29:43.780)
I have to, I stand behind star shade in all cases, so, but there is this other kind of
Sara Seager (1:29:48.900)
field that I, that everyone is involved in because star shade is hard.
Sara Seager (1:29:53.220)
Earths are hard, but there are, there's another category of planet star type that's easier.
Lex Fridman (1:29:58.900)
And these are planets orbiting small red dwarf stars.
Lex Fridman (1:30:02.780)
They're not earth like at all.
Sara Seager (1:30:04.160)
Think like earth cousin instead of earth twin, but there's a chance that we might establish
Lex Fridman (1:30:08.060)
that some of those have water and signs of life on them.
Sara Seager (1:30:11.500)
It's nearer term than star shade and we're all working hard on that too.
Sara Seager (1:30:15.500)
Let me ask by way of recommendations, I think a lot of people are curious about this kind
Sara Seager (1:30:20.220)
of stuff.
Lex Fridman (1:30:21.220)
What three books, technical or fiction or philosophical or anything really had an impact
Sara Seager (1:30:27.400)
on your life and, and or you would recommend besides of course your book.
Lex Fridman (1:30:35.860)
There's one book I wish everyone could read.
Sara Seager (1:30:38.660)
I'm not sure if you've read it.
Lex Fridman (1:30:39.780)
It's actually a children's book, like a young adult book.
Sara Seager (1:30:42.300)
It's called the giver.
Lex Fridman (1:30:43.780)
Yes.
Lex Fridman (1:30:44.780)
And it is the book that kids in school read now.
Lex Fridman (1:30:48.660)
And I only, sorry, that's not, that's wow.
Sara Seager (1:30:52.820)
Sorry, that, that caught me off guard.
Lex Fridman (1:30:57.300)
So when I first came to this country, I didn't speak much.
Sara Seager (1:30:59.620)
It's really what made me, it had a profound impact on my life and a really important moment
Lex Fridman (1:31:05.980)
because they give it to kids.
Sara Seager (1:31:07.660)
Like I think middle school, I think, or maybe elementary, something like that.
Lex Fridman (1:31:10.580)
I'm so surprised you've even heard of this book.
Sara Seager (1:31:12.580)
Yeah.
Lex Fridman (1:31:13.580)
So they give it, but like it's the value of giving the right book to a person at the right
Sara Seager (1:31:17.140)
time.
Lex Fridman (1:31:18.140)
Wow.
Sara Seager (1:31:19.140)
I was, I was, cause it's very accessible.
Lex Fridman (1:31:22.300)
Do we want to share what the story is without spoiling it?
Lex Fridman (1:31:25.140)
Oh yeah, you can without spoiling, right?
Lex Fridman (1:31:28.100)
It follows this boy in this very utopic society.
Sara Seager (1:31:32.200)
That's like perfect.
Lex Fridman (1:31:33.200)
It's been all clean cut and made perfect actually.
Lex Fridman (1:31:35.140)
And as he kind of comes of age, he starts realizing something's wrong with his world.
Lex Fridman (1:31:41.340)
And so it's part of that question.
Sara Seager (1:31:42.600)
Are we going to evolve as, I mean, this isn't what's there, but it made me wonder, you know,
Lex Fridman (1:31:45.700)
are we evolving to a better place?
Sara Seager (1:31:47.660)
Is there a day when we can eliminate, you know, poverty and hunger and crime and sickness
Sara Seager (1:31:52.980)
in this book, they pretty much have in a society that the boys in and sort of follows him.
Lex Fridman (1:31:58.260)
And he becomes a chosen one to be like a receiver.
Sara Seager (1:32:01.800)
The givers, the old wise man who retains some of the harshness of the outside world so that
Sara Seager (1:32:06.820)
he can advise the people as a sort of boy comes of age and is chosen for the special
Lex Fridman (1:32:11.140)
role.
Sara Seager (1:32:12.140)
He finds the world isn't what he expects.
Lex Fridman (1:32:13.840)
And I don't know about you, but it was so profound for me because it jolts you out of
Sara Seager (1:32:17.820)
reality.
Lex Fridman (1:32:18.820)
It's like, Oh my God, what am I doing here?
Sara Seager (1:32:19.940)
I'm just going with the flow with my society.
Lex Fridman (1:32:22.860)
How do I think outside the box and the confines of my society, which surely carries negative
Sara Seager (1:32:26.820)
things with it that we don't realize today.
Sara Seager (1:32:28.860)
Yeah, and also in the flip side of that is if you do take a step outside the box on occasion,
Lex Fridman (1:32:36.540)
what's the psychological burden of that?
Lex Fridman (1:32:39.300)
Like is that, is that a step you want to take?
Lex Fridman (1:32:42.340)
Is that the journey you want to take?
Lex Fridman (1:32:44.980)
What is that life like?
Sara Seager (1:32:45.980)
I don't know.
Lex Fridman (1:32:46.980)
I felt like from the book, you have to take it.
Sara Seager (1:32:48.180)
I found from the book, I never thought like now that you're saying it, I see what you're
Lex Fridman (1:32:52.540)
saying.
Sara Seager (1:32:53.540)
The burden is huge, but I always felt like the answer is yes, you absolutely want to
Lex Fridman (1:32:56.340)
know what's outside.
Lex Fridman (1:32:57.340)
But you can't do that if you're very, it's hard to be objective about your own reality.
Lex Fridman (1:33:01.860)
Yeah.
Sara Seager (1:33:02.860)
I mean, it's a very human instinct, but, uh, it also, the book kind of shows that, uh,
Sara Seager (1:33:08.620)
it has an effect on you and this, it's a really interesting question about our society and
Sara Seager (1:33:14.060)
taking a step out.
Lex Fridman (1:33:16.320)
It's by, uh, Lois Lowry, I think is how you pronounce it.
Sara Seager (1:33:20.580)
I really do hope everyone created it and it is a young adult book, but it's still, it's
Lex Fridman (1:33:24.160)
incredibly, I'm really glad I only read it cause my kids got it for school.
Lex Fridman (1:33:27.300)
I just thought, okay, well, why don't I just see what this is about?
Lex Fridman (1:33:29.780)
And I just, wow.
Sara Seager (1:33:31.780)
Yeah.
Lex Fridman (1:33:32.780)
Yeah.
Sara Seager (1:33:33.780)
I think it's also the value of education.
Lex Fridman (1:33:35.180)
I think I'm surprised you mentioned, I've never really mentioned to anybody.
Sara Seager (1:33:38.860)
I'm sure a lot of people had the similar experience like me and maybe it's a generational thing
Lex Fridman (1:33:44.020)
though, because like the book came out, I think in the nineties.
Lex Fridman (1:33:46.340)
So if you're older than like me, that book didn't exist when we were in middle school.
Lex Fridman (1:33:50.980)
So I just do think a lot of people won't have heard of it, but it's an interesting question
Sara Seager (1:33:54.700)
of like those books.
Sara Seager (1:33:58.260)
I mean, I'm reminded often, I suppose the same is true with other subjects, but books
Sara Seager (1:34:03.060)
are special at the early age, like middle school, maybe early high school, those can
Lex Fridman (1:34:09.260)
change like the direction of your life.
Lex Fridman (1:34:11.980)
And also certainly teachers, they can change completely the direction of your life.
Sara Seager (1:34:17.940)
There's so many stories about teachers of mathematics, teachers of physics, of any kind
Sara Seager (1:34:24.140)
of subjects basically changing the direction of a human's life.
Sara Seager (1:34:27.580)
That's like not to get on the whole, almost like a political thing, but you know, we,
Sara Seager (1:34:36.220)
we undervalue teachers.
Lex Fridman (1:34:38.860)
It's a special, it's a special position that they hold.
Sara Seager (1:34:42.060)
That's so true.
Lex Fridman (1:34:43.060)
Yeah.
Sara Seager (1:34:44.060)
Well, I do have two other books or two other things.
Lex Fridman (1:34:46.740)
One is something I came across just a few days ago, actually.
Sara Seager (1:34:50.100)
It's actually a film called Picture a Scientist.
Lex Fridman (1:34:54.820)
And when you picture a scientist, you probably don't picture the women and women of color
Sara Seager (1:34:59.680)
in this film.
Lex Fridman (1:35:01.140)
And it is a way to get outside your box.
Sara Seager (1:35:03.860)
I really think everyone interested in science, even just peripherally should watch this because
Lex Fridman (1:35:09.020)
it is shocking and sobering at the same time.
Lex Fridman (1:35:12.580)
And it talks about how, well, I think one of the messages across is, you know, we really
Sara Seager (1:35:17.820)
are like, I don't know if we're hardwired to just like people like ourselves, but we're
Sara Seager (1:35:22.580)
excluding a lot of people and therefore a lot of great ideas by not being able to think
Lex Fridman (1:35:27.020)
outside of how we're all stereotyping each other.
Lex Fridman (1:35:30.780)
So it's, it's, it's hard to kind of convey that and you can just say, oh yeah, I want
Lex Fridman (1:35:34.060)
to be more diverse.
Sara Seager (1:35:35.060)
I want to be more open, but it's a nearly impossible problem to solve and the movie
Lex Fridman (1:35:38.860)
really helps open people's eyes to it.
Sara Seager (1:35:42.420)
This book I put third because unlike The Giver, people may not want to read it.
Lex Fridman (1:35:46.780)
It's not as relevant.
Lex Fridman (1:35:47.780)
But when I was in my early twenties, I went to this big, this like 800 people large conference
Lex Fridman (1:35:56.180)
run by the Wilderness Canoe Association in my hometown of Toronto.
Lex Fridman (1:36:00.340)
And there was a family friend there who I met and he said, read this book, it'll change
Lex Fridman (1:36:04.780)
your life.
Lex Fridman (1:36:06.060)
And it actually changed my life.
Lex Fridman (1:36:08.220)
And it was a book called Sleeping Island by an author, PG Downs, who just coincidentally
Sara Seager (1:36:13.820)
lived in this area, lived in the Boston area and he was a teacher, I think at a private
Lex Fridman (1:36:17.820)
school and every summer he would go to Canada with a canoe often by himself.
Lex Fridman (1:36:23.580)
And he wrote this book maybe in the forties or fifties about a trip he took in the late
Lex Fridman (1:36:27.380)
1930s.
Lex Fridman (1:36:28.380)
And it was, I was just shocked that even at that time, although that was a long time ago,
Lex Fridman (1:36:32.700)
there were large parts of Canada that were untouched by white people.
Lex Fridman (1:36:37.580)
And he went up there and interacted like with the natives.
Sara Seager (1:36:40.480)
He called the book and had a subtitle that was called, there's something like Journey
Sara Seager (1:36:45.560)
in the Barren Lands.
Lex Fridman (1:36:47.400)
And when you go up North in Canada, you pass the tree line, just like on a mountain, if
Sara Seager (1:36:50.740)
you hike up a mountain, you get so far North there aren't any trees.
Lex Fridman (1:36:53.580)
And he wrote eloquently about the land and about being out there.
Sara Seager (1:36:56.300)
There weren't even any maps of the region, like in that time.
Lex Fridman (1:37:00.520)
And I just thought to myself, wow, like that you could just take the summer off and explore
Sara Seager (1:37:04.540)
by canoe and go and see what's out there.
Lex Fridman (1:37:07.540)
And it led to me just doing that, that very thing.
Sara Seager (1:37:10.620)
Of course it's different now, but going out to where the road ends and putting the canoe
Lex Fridman (1:37:14.980)
in the water and just, well, we had to have a plan.
Sara Seager (1:37:16.740)
We didn't just explore, but go down this river, rivers with rapids and travel over lakes and
Lex Fridman (1:37:21.780)
portages and just really live.
Lex Fridman (1:37:25.540)
So just really explore, screw it.
Sara Seager (1:37:27.540)
That doesn't like, it doesn't explore just use from a topo map, from a topographical
Sara Seager (1:37:31.540)
map from the library.
Sara Seager (1:37:33.540)
There were scary elements about it, out of it, but part of the excitement or the joy
Sara Seager (1:37:41.100)
or the desire was to be scared, like it was to go out there and have live on the edge.
Lex Fridman (1:37:45.900)
And persevere.
Sara Seager (1:37:46.900)
Yeah.
Lex Fridman (1:37:47.900)
And persevere.
Sara Seager (1:37:48.900)
Yeah.
Lex Fridman (1:37:49.900)
Do you have a advice that you would give to a young person today that would like to help
Sara Seager (1:37:56.540)
you maybe on the planetary science side, discover exoplanets or maybe bigger picture, just
Lex Fridman (1:38:03.140)
succeed in life?
Sara Seager (1:38:04.140)
I do have some advice just to succeed.
Sara Seager (1:38:06.380)
It's tough advice in a way, but it is to find something that you love doing that you're
Sara Seager (1:38:11.260)
also very good at.
Lex Fridman (1:38:13.060)
And in some ways the stars have to align because you've got to find that thing you're good
Sara Seager (1:38:17.500)
at or the range of things, and it actually has to overlap with something that actually
Lex Fridman (1:38:21.780)
you love doing every day.
Lex Fridman (1:38:23.340)
So it's not a tedious job.
Lex Fridman (1:38:26.140)
That's the best way to succeed.
Lex Fridman (1:38:27.500)
What were the signals that in your own life were there to make you realize you're good
Lex Fridman (1:38:33.060)
at something?
Lex Fridman (1:38:35.780)
What were you good at that made you pursue a PhD and it made you pursue the search?
Lex Fridman (1:38:44.180)
I mean, that was the one sentence version.
Sara Seager (1:38:46.980)
In my case, it was a long slog and there were a lot of things I wasn't good at initially.
Lex Fridman (1:38:51.220)
But so initially, I was good at high school math.
Sara Seager (1:38:53.180)
I was good at high school science.
Lex Fridman (1:38:55.140)
I loved astronomy and I realized those could all fit together.
Sara Seager (1:38:58.580)
Like the day I realized you could be an astronomer for a job, it has to be one of my top days
Lex Fridman (1:39:02.740)
of my life.
Sara Seager (1:39:03.740)
I didn't know that you could be that for a job and I was good at all those things.
Lex Fridman (1:39:08.020)
And although my dad wanted me to do something more practical where he could be guaranteed
Sara Seager (1:39:11.540)
I could support myself was another option, but initially I wasn't that good at physics.
Sara Seager (1:39:16.860)
It was a slog to just get through school and grad school is a very, very long time.
Lex Fridman (1:39:21.140)
And ultimately, when faced with a choice and I had the luxury of choosing, knowing that
Lex Fridman (1:39:26.220)
I was good at something and also loved it, it really carried me through.
Sara Seager (1:39:29.060)
Now, I asked some of the smartest people in the world the most ridiculous question.
Lex Fridman (1:39:34.380)
We already talked about it a little bit, but let me ask again, why are we here?
Sara Seager (1:39:42.140)
I think you've raised this question in one of your presentations as like one of the things
Sara Seager (1:39:47.020)
that we kind of as humans long to answer and the search for exoplanets is kind of part
Sara Seager (1:39:52.940)
of that.
Lex Fridman (1:39:53.940)
But what do you think is the meaning of it all, of life?
Sara Seager (1:39:57.220)
I wish I had a good answer for you.
Lex Fridman (1:40:02.980)
I think you're the first person ever who refused to answer the question.
Sara Seager (1:40:07.140)
It's not so much refusing, I just, yeah, I mean, I wish I had a better answer.
Lex Fridman (1:40:11.540)
It's why we're here.
Sara Seager (1:40:12.860)
It's almost like the meaning is wishing there was a meaning, wishing we knew.
Lex Fridman (1:40:20.540)
I love that.
Sara Seager (1:40:21.540)
That's a great way to say it.
Lex Fridman (1:40:24.460)
Sarah, like I said, the book is excellent.
Sara Seager (1:40:27.140)
I admired your work from afar for a while and I think you're one of the great stars
Lex Fridman (1:40:33.620)
at MIT.
Sara Seager (1:40:34.620)
It makes me proud to be part of the community.
Lex Fridman (1:40:37.340)
So thank you so much for your work.
Sara Seager (1:40:40.260)
Thank you for inspiring all of us.
Lex Fridman (1:40:41.500)
Thanks for talking today.
Sara Seager (1:40:42.500)
Thank you so much, Lynx.
Lex Fridman (1:40:45.060)
Thanks for listening to this conversation with Sarah Seager.
Lex Fridman (1:40:47.500)
And thank you to our sponsors, Public Goods, Power Dot, and Cash App.
Lex Fridman (1:40:53.040)
Click the links in the description to get a discount.
Sara Seager (1:40:55.700)
It's the best way to support this podcast.
Sara Seager (1:40:57.820)
If you enjoy this thing, subscribe on YouTube, review it with five stars on Apple Podcast,
Sara Seager (1:41:02.700)
support it on Patreon, or connect with me on Twitter at Lex Friedman, spelled I'm not
Lex Fridman (1:41:07.700)
sure how.
Sara Seager (1:41:08.980)
Just keep typing stuff in until you get to the guy with the tie and the thumbnail.
Lex Fridman (1:41:14.740)
And now let me leave you with some words from Carl Sagan, somewhere something incredible
Sara Seager (1:41:20.500)
is waiting to be known.
Lex Fridman (1:41:23.000)
Thank you for listening and hope to see you next time.
Sara Seager (20:00.520)
You're not going to be able to find planets around them.
Lex Fridman (20:02.640)
So I need to know the fraction of those that are, that are good.
Lex Fridman (20:05.960)
So again, we have the number of stars, the fraction of them that we can actually find
Lex Fridman (20:09.200)
planets around.
Lex Fridman (20:10.200)
And by the way, is our sun one such, is our sun quiet?
Lex Fridman (20:16.520)
Our sun is quiet.
Sara Seager (20:17.520)
Okay.
Lex Fridman (20:18.520)
So I have actually two terms.
Sara Seager (20:20.280)
One describes how quiet they are and one is if we can find a planet around that star.
Sara Seager (20:25.580)
These transiting planets, for example, not all planets transit because the planet would
Sara Seager (20:30.180)
have to be orbiting that star in this kind of plane as viewed from you.
Lex Fridman (20:36.360)
But if a star is, for example, orbiting in the plane of the sky, it will never transit.
Sara Seager (20:40.360)
It will never go in front of the star.
Lex Fridman (20:43.000)
So in that case, we have to have a fraction that takes into account of that kind of geometric
Sara Seager (20:47.560)
factor.
Lex Fridman (20:48.640)
And hopefully, I mean, you can assume that it's uniformly distributed, hopefully.
Sara Seager (20:52.840)
Yes, we can assume and there's evidence that it's uniformly distributed, yes.
Lex Fridman (20:56.980)
So then the next, so all of these factors so far, number of stars accessible to whatever
Sara Seager (21:01.600)
telescope you're thinking about, how many stars are quiet, fraction of stars that are
Sara Seager (21:06.520)
quiet, fraction that are observable, in this case for the geometric factor, those are all
Sara Seager (21:10.380)
things we can measure.
Lex Fridman (21:11.380)
And there's one more term in the secret equation we can measure.
Sara Seager (21:14.920)
I call it fraction of planets in the habitable zone.
Lex Fridman (21:18.540)
Because believe it or not, we have a handle on that for a certain set of stars.
Sara Seager (21:23.760)
We know from our, the Kepler Space Telescope that operated for a number of years, we have
Sara Seager (21:28.520)
estimates for how many planets are in the so called habitable zone of the host star
Sara Seager (21:31.840)
for a certain type of star.
Lex Fridman (21:33.420)
So all those we have measurable.
Lex Fridman (21:34.960)
And then like the Drake equation itself, there are some terms we can not measure.
Lex Fridman (21:39.280)
And those ones, I call them FL, fraction of all those planets that have life on them.
Sara Seager (21:46.280)
Because we don't know what that is.
Lex Fridman (21:47.400)
And FS, I called for spectroscopy, the fraction that have, we can use our telescope and instrument
Sara Seager (21:55.300)
tools to look for light.
Sara Seager (21:58.080)
The FS was the ones that, the planets that have life that actually gives off a gas, a
Sara Seager (22:03.880)
useful gas that might accumulate in the atmosphere, so we could eventually observe it.
Lex Fridman (22:10.160)
How do the FL and FS interplay?
Lex Fridman (22:12.280)
So these are separate terms?
Lex Fridman (22:14.320)
Separate terms.
Lex Fridman (22:15.560)
And so?
Lex Fridman (22:16.560)
So for example, you could imagine, so for example, you could imagine life, like us humans,
Sara Seager (22:23.720)
we breathe out carbon dioxide.
Lex Fridman (22:26.680)
And our planet Earth, we already have a lot of carbon dioxide on it.
Sara Seager (22:29.560)
Well, we have hundreds of parts per million, but it has a really strong signal.
Lex Fridman (22:33.600)
So us humans breathing out carbon dioxide, it's not helpful for any intelligent beings
Sara Seager (22:37.500)
that are looking back at Earth, because there's already a lot of, there's already enough carbon
Lex Fridman (22:41.120)
dioxide, we're not adding to it.
Lex Fridman (22:43.060)
So if there is life on a planet, and it's outputting a boring gas that's not helpful
Sara Seager (22:47.320)
for us to uniquely identify as being made by life versus just being there anyway, then
Sara Seager (22:54.440)
it's not helpful.
Lex Fridman (22:55.440)
So I separated those two terms out.
Sara Seager (22:57.960)
Soon I think we'll have evidence that planets that can support life at least are common.
Lex Fridman (23:04.320)
So okay, this is such an awesome topic, I have a million questions.
Lex Fridman (23:11.080)
What okay, I know this is a little bit of speculation, but what's your sense about that,
Sara Seager (23:16.080)
I think FS, which is like, that life would produce interesting gases that would be able
Sara Seager (23:23.760)
to detect, like, is there, one, is there scientific evidence and, and second, is there some intuition
Lex Fridman (23:30.480)
around life producing gases with detectable hints in terms of chemistry?
Lex Fridman (23:36.820)
So interestingly enough, that entire question relates to, I'm going to say almost my life's
Sara Seager (23:43.160)
work, the work I'm doing now and the work I'm doing for the next 20 years, and I wish
Sara Seager (23:46.520)
I could give you a concrete number, like 1%, like on the worst days, it's 1%, let's say
Lex Fridman (23:51.440)
in my mind.
Sara Seager (23:52.440)
You know, in the best days, it's like 80%.
Lex Fridman (23:54.480)
And I could actually go into a lot of detail here, but I'll just give you the simplest
Sara Seager (23:58.400)
things.
Lex Fridman (23:59.920)
So first of all, we make an assumption that like us, and our life here on Earth, life
Sara Seager (24:05.800)
uses chemistry.
Lex Fridman (24:07.700)
So we use chemistry because we eat food, we breathe air, and we have metabolism that to
Sara Seager (24:13.120)
break down food to get energy to store energy, and then ultimately to use it.
Lex Fridman (24:18.820)
And all life here has some kind of byproduct in doing all that, some kind of waste product
Sara Seager (24:22.560)
that goes into the atmosphere.
Lex Fridman (24:24.400)
So I like to think that life everywhere uses chemistry.
Sara Seager (24:28.700)
Some people have imagined, like, let's imagine like a windmill, like mechanical energy, just
Lex Fridman (24:34.280)
getting energy and using it without storing it.
Lex Fridman (24:37.120)
And if there was life like that, it might not need to output a gas.
Lex Fridman (24:40.840)
So we make this basic assumption of chemistry, that's the first thing.
Sara Seager (24:44.040)
The second more complicated thing that I and my team work on is what happens to the gas
Lex Fridman (24:47.960)
once it is produced by life, it goes into the atmosphere.
Lex Fridman (24:51.980)
And a lot of gas is just destroyed immediately, actually, by ultraviolet radiation or by oxygen.
Lex Fridman (24:59.600)
Oxygen is incredibly destructive to a lot of gases.
Lex Fridman (25:03.540)
So the gas can be produced by life, but it could be just completely destroyed by its
Lex Fridman (25:07.280)
environment.
Sara Seager (25:08.280)
I guess we should pause on that, that you mentioned your life's work.
Sara Seager (25:13.800)
This is just the beautiful idea that it's kind of paralyzing when you look out there
Lex Fridman (25:19.280)
and you wonder, is there a life out there?
Sara Seager (25:22.720)
It's the first paralyzing, actually, before I encountered your work, I feel like an idiot.
Lex Fridman (25:27.360)
But you know, it feels like there's no tool to answer that question.
Lex Fridman (25:32.860)
And then what you kind of provided is this cool idea that it might be possible to answer
Sara Seager (25:40.000)
that by looking at the gases.
Lex Fridman (25:41.240)
I mean, that's a really interesting, that's a beautiful idea.
Lex Fridman (25:45.720)
And yeah, so we could just pause on like, that's a powerful tool, I think, to build
Lex Fridman (25:55.280)
the intuition around, because I was totally clueless about it.
Lex Fridman (25:57.800)
And that was kind of exciting.
Sara Seager (25:59.440)
I mean, I'm sure there's folks probably early on in your life who were very skeptical about
Sara Seager (26:05.760)
this notion.
Sara Seager (26:06.760)
Well, maybe I'm not sure, but generally you would want to be skeptical, it's like, well,
Sara Seager (26:13.320)
all these kinds of other things could generate gases, you know, all those kinds of things.
Lex Fridman (26:17.000)
Oh, that's so true.
Lex Fridman (26:18.000)
And that's a big part of this growing field is how to make sure that this gas isn't produced
Lex Fridman (26:23.240)
by another effect.
Lex Fridman (26:24.240)
But I do want to, you know, again, pausing on that and going back a bit.
Sara Seager (26:29.000)
It's incredible to think, but like, at least almost 100 years ago, there's a record of
Sara Seager (26:33.100)
someone talking about the idea of a gas being an indicator of life elsewhere.
Lex Fridman (26:38.720)
That idea was floating about somewhere.
Sara Seager (26:40.240)
Yes, it was totally floating about.
Lex Fridman (26:42.040)
And it comes down to oxygen, which on our planet fills our atmosphere to 20% by volume.
Lex Fridman (26:48.440)
And you know, we rely on oxygen to breathe.
Sara Seager (26:50.600)
You know, when you hear about the people in Mount Everest running out of air, they're
Sara Seager (26:54.280)
really running out of oxygen, well, they're running out of oxygen because the air is getting
Lex Fridman (26:57.660)
thinner as they climb up the mountain.
Lex Fridman (27:01.680)
But without plants and bacteria, there's bacteria that also photosynthesizes and produces oxygen
Lex Fridman (27:08.680)
as a waste product.
Sara Seager (27:09.680)
Without those, we would have virtually no oxygen.
Lex Fridman (27:13.040)
Our atmosphere would be devoid of oxygen.
Lex Fridman (27:15.480)
So yeah, if you were to analyze Earth, is oxygen the strong indicator here?
Lex Fridman (27:21.900)
Oxygen is a huge indicator.
Lex Fridman (27:22.900)
And that's what we're hoping, that there is an intelligent civilization not too far from
Sara Seager (27:26.720)
here around a planet orbiting a nearby star with the kind of telescopes we're trying to
Sara Seager (27:31.440)
build.
Lex Fridman (27:32.440)
And they're looking back at our sun and they've seen our Earth and they see oxygen.
Lex Fridman (27:36.740)
And they probably won't be like 100.0% sure that there's life making it.
Lex Fridman (27:41.620)
But if they go through all the possible scenarios, they'll be left with a pretty strong hint
Sara Seager (27:45.820)
that there's life here.
Lex Fridman (27:46.820)
Yeah.
Lex Fridman (27:47.820)
Okay, but how do you detect that type of gases that are on the planet from a distance?
Lex Fridman (27:55.360)
And that's going back to that, that's what people were skeptical about.
Sara Seager (28:00.160)
When I first started working on exoplanets a long time ago, people didn't believe we
Lex Fridman (28:04.800)
would ever, ever, ever study an exoplanet atmosphere of any kind.
Lex Fridman (28:09.500)
And now dozens of them are studied.
Sara Seager (28:11.320)
There's a whole field of people, hundreds of people working on exoplanet atmospheres
Sara Seager (28:14.520)
actually.
Lex Fridman (28:15.520)
Wow.
Lex Fridman (28:16.520)
But first there was a point where people didn't even know there was exoplanets, right?
Lex Fridman (28:20.240)
When was the first exoplanet detected?
Sara Seager (28:23.100)
The first exoplanet around a sun like star anyway was detected in the mid 1990s.
Lex Fridman (28:27.200)
That was a big deal.
Sara Seager (28:29.600)
Kind of vaguely remember that.
Lex Fridman (28:30.600)
Well, at the time it was a big deal, but it was also incredibly controversial.
Sara Seager (28:34.840)
Because in exoplanets, we only had one example of a planetary system, our own solar system.
Lex Fridman (28:41.280)
And in our solar system, Jupiter, our big massive planet, is really far from our star.
Lex Fridman (28:48.000)
And this first exoplanet around a sun like star was incredibly close to its star, so
Lex Fridman (28:53.000)
close that people just couldn't believe it was a planet actually.
Lex Fridman (28:56.180)
So maybe zoom out, what the heck is an exoplanet?
Sara Seager (29:00.080)
An exoplanet is our name, like is the name that we call a planet orbiting a star other
Sara Seager (29:05.500)
than our sun.
Lex Fridman (29:07.000)
Right.
Sara Seager (29:08.000)
Extrasolar, I guess is another.
Lex Fridman (29:09.000)
You can call it extrasolar.
Sara Seager (29:10.000)
Okay.
Lex Fridman (29:11.000)
Exoplanet is simpler.
Lex Fridman (29:12.000)
But I think it's worth pausing to remember that each one of those stars out there in
Lex Fridman (29:17.140)
our night sky is a sun.
Lex Fridman (29:18.800)
And you know, our sun has planets, Mercury, Venus, Earth, Mars, etc.
Lex Fridman (29:23.440)
And so for a long time, people have wondered, do those other stars or other suns have planets?
Lex Fridman (29:29.160)
And they do.
Lex Fridman (29:30.160)
And it appears that nearly every star has a planet, has a planet we call exoplanet.
Lex Fridman (29:34.040)
And there are thousands of known exoplanets already.
Lex Fridman (29:37.000)
So there's already, yeah, like, there's so many things about space that it's hard to
Sara Seager (29:42.120)
put into one's brain, because it starts filling it with awe.
Lex Fridman (29:47.520)
So yeah, if you visualize the fact that the stars that we see in the sky aren't just stars,
Sara Seager (29:54.920)
they're like, they're suns.
Lex Fridman (29:57.160)
And they very likely, as you're saying, would have planets around them.
Sara Seager (30:03.520)
There's all these planets roaming about in this like, dimly lit darkness, with potentially
Lex Fridman (30:11.240)
life.
Sara Seager (30:12.240)
I mean, it's just mind blowing.
Lex Fridman (30:14.920)
But maybe can you give a brief, like, history of discovering all the exoplanets?
Lex Fridman (30:23.120)
So there's no exoplanets in the 90s.
Lex Fridman (30:26.320)
And then there's a lot of exoplanets now.
Lex Fridman (30:28.500)
So how did that come about?
Lex Fridman (30:29.600)
So many planets.
Lex Fridman (30:31.520)
How did it come about?
Sara Seager (30:32.520)
Well, maybe another way to ask is, what is the methodology that was used to discover
Lex Fridman (30:37.120)
them?
Lex Fridman (30:38.120)
I can say that.
Lex Fridman (30:39.120)
But I'd like to just say something else first where, so exoplanets, you know, the line
Lex Fridman (30:43.680)
between what is considered completely crazy.
Lex Fridman (30:47.160)
And what is considered mainstream research, legit, is constantly shifting.
Lex Fridman (30:51.600)
This is awesome.
Sara Seager (30:52.600)
Yeah.
Lex Fridman (30:53.600)
So before, when I started on exoplanets, it was still sketchy.
Sara Seager (30:56.040)
Like, it wasn't considered a career, a thing, a place where you should be investing.
Lex Fridman (31:01.280)
And right now, now, today, it's so many people are working in this field, a good, I don't
Sara Seager (31:06.840)
know, at least 1000, probably more.
Lex Fridman (31:08.480)
I don't know if that sounds like a lot to you, but it's a lot.
Sara Seager (31:10.840)
No, it's a legitimate field of inquiry.
Lex Fridman (31:13.800)
Yeah.
Sara Seager (31:14.800)
Legitimate field of inquiry.
Lex Fridman (31:15.800)
And what's helped us is everything that's helped everyone else.
Sara Seager (31:18.000)
It's software, it's computers, it's hardware.
Lex Fridman (31:21.720)
It's like our phones.
Sara Seager (31:22.720)
You have a fantastic detector in there.
Lex Fridman (31:23.960)
Like, they didn't always have that.
Sara Seager (31:25.120)
I don't know if you remember the so called olden days.
Lex Fridman (31:28.080)
We didn't have digital cameras.
Sara Seager (31:29.300)
We had film.
Sara Seager (31:30.580)
You take a film camera, you send the film away, and eventually it comes back, and then
Sara Seager (31:33.680)
you see your pictures.
Lex Fridman (31:34.680)
And they could all be horrible.
Sara Seager (31:35.680)
Yeah.
Lex Fridman (31:36.680)
So yeah, I mean, digital.
Sara Seager (31:37.680)
It just changed everything.
Lex Fridman (31:38.680)
Data changed everything.
Sara Seager (31:39.680)
Yeah, and so one thing that really helped exoplanets were detectors that were very sensitive.
Sara Seager (31:45.920)
Because when we're looking for the transiting planets, what we're doing is we're monitoring
Sara Seager (31:51.100)
a star's brightness as a function of time.
Lex Fridman (31:53.840)
It's like click, taking a picture of the stars every few seconds or minutes.
Lex Fridman (31:58.840)
And we're measuring the brightness of a star, like every frame.
Lex Fridman (32:02.960)
And we're looking for a drop in brightness that's characteristic of a planet going in
Sara Seager (32:06.700)
front of the star, and then finishing its so called transit.
Lex Fridman (32:11.680)
And to make that measurement, we have to have precise detectors.
Lex Fridman (32:15.960)
And the detectors that are making the measurement, can you do it from Earth?
Lex Fridman (32:22.080)
Are they floating about in space, like what kind of telescope?
Lex Fridman (32:25.920)
So on the ground, people are using telescopes, small telescopes that are almost just like
Lex Fridman (32:30.260)
a glorified telephoto lens.
Lex Fridman (32:32.520)
And they're looking at big swaths of the sky.
Lex Fridman (32:35.140)
And from the ground, people can find giant planets like the size of Jupiter.
Lex Fridman (32:38.820)
So it's about 10 to 12 times the size of Earth.
Lex Fridman (32:41.700)
We can find big planets, because we can reach about 1% precision.
Lex Fridman (32:46.320)
So not sure how technical you want to get.
Lex Fridman (32:48.680)
Well, how many pixels are we talking about?
Sara Seager (32:53.080)
You mentioned phones, there's a bunch of megapixels, I think.
Lex Fridman (32:56.820)
So for exoplanets, you want to think about it as like a pixel or less than a pixel, we're
Sara Seager (33:01.240)
not getting any information.
Lex Fridman (33:03.940)
But to be more technical, our telescope spreads the light out over many pixels, but we're
Sara Seager (33:08.040)
not getting information.
Lex Fridman (33:09.300)
We're not tiling the planet with pixels.
Sara Seager (33:12.300)
It's just like a point of light, or in most cases, we don't even see the planet itself,
Lex Fridman (33:16.320)
just the planet's effect on the star.
Lex Fridman (33:17.920)
But another thing that really helped was computers, because transiting planets are actually quite
Lex Fridman (33:22.640)
rare.
Sara Seager (33:23.640)
I mean, they don't all go in front of their star.
Lex Fridman (33:25.560)
And so to find transiting planets, we look at a big part of the sky at once, or we look
Sara Seager (33:29.880)
at tens of thousands or hundreds of thousands, or even in some cases, millions of stars at
Lex Fridman (33:34.100)
one time.
Lex Fridman (33:35.520)
And so you're not going to do this by hand, going through a million stars, counting up
Lex Fridman (33:39.400)
the brightness.
Lex Fridman (33:40.400)
So we have computer software and computer code that does the job for us and counts the
Lex Fridman (33:47.600)
brightness and looks for a signal that could be due to a transiting planet.
Lex Fridman (33:51.880)
And I just finished a job called Deputy Science Director for the MIT led NASA mission test.
Lex Fridman (33:59.440)
And it was my purview to make sure that we got the planet candidates, the transiting
Sara Seager (34:05.880)
light curves, out to the community so people could follow them up and figure out if they're
Lex Fridman (34:10.280)
actual planets or false positives.
Lex Fridman (34:13.360)
So publish the data so that people could just, all the data scientists out there could crunch
Lex Fridman (34:19.260)
and see if they can discover something.
Sara Seager (34:21.080)
They can discover something.
Lex Fridman (34:22.080)
And in fact, the NASA policy for this mission is that all the data becomes public as soon
Sara Seager (34:26.760)
as possible.
Sara Seager (34:28.360)
It's not as easy as it sounds, though, to download the data and look for planets.
Lex Fridman (34:33.680)
But there is a group called PlanetHunters.org, and they take the data and they actually crowdsource
Lex Fridman (34:38.600)
it out to people to look for planets.
Sara Seager (34:40.200)
Yeah.
Lex Fridman (34:41.200)
And they often find signals that our computers and our team missed.
Lex Fridman (34:44.940)
So we mentioned exoplanets.
Lex Fridman (34:46.880)
What about Earth like, or I don't know what the right distinction is, is it habitable
Sara Seager (34:51.920)
or is it Earth like planets, but what are those different categories and how can we
Lex Fridman (34:55.940)
tell the difference and detect each?
Sara Seager (34:57.840)
Right, right.
Lex Fridman (34:58.840)
So we're not at Earth like planets yet.
Sara Seager (35:01.360)
All the planets we're finding are so different from what we have in our solar system.
Lex Fridman (35:06.680)
They're just easier planets to find, but like...
Lex Fridman (35:08.640)
In which way?
Lex Fridman (35:09.640)
For example, there could be a Jupiter sized planet where an Earth should be.
Sara Seager (35:14.740)
We find planets that are the same size as Earth, but are orbiting way closer to their
Lex Fridman (35:20.720)
star than Mercury is to our sun.
Sara Seager (35:24.080)
They're so close that, because close to a star means they also orbit faster.
Lex Fridman (35:29.160)
And some of these hot super Earths we call them, their year, their time to go around
Sara Seager (35:33.860)
their star is less than a day.
Lex Fridman (35:36.940)
And they're heated so much by their star, they're heated so much by the star.
Sara Seager (35:40.480)
We think the surface is hot enough to melt rock.
Lex Fridman (35:42.920)
So instead of running out by the bay or the river, you'll have like liquid lava.
Sara Seager (35:47.520)
There'll be liquid lava lakes on these planets, we think.
Lex Fridman (35:51.480)
And life can't survive.
Sara Seager (35:53.520)
Way too hot.
Sara Seager (35:54.520)
The molecules needed for life just wouldn't be able to survive those temperatures.
Sara Seager (35:59.760)
We have some other planets.
Sara Seager (36:00.760)
One of the most mysterious things out there, factoid, if you will, is that the most common
Sara Seager (36:07.000)
type of planet we know about so far is a planet that's in between Earth and Neptune size.
Lex Fridman (36:12.920)
It's two to three times the size of Earth.
Lex Fridman (36:15.680)
And we have no solar system counterpart of that planet.
Sara Seager (36:19.840)
That is like going outside to the forest and finding some kind of creature or animal that
Sara Seager (36:24.000)
just no one has ever seen before and then discovering that is the most common thing
Lex Fridman (36:27.360)
out there.
Lex Fridman (36:29.320)
And so we're not even sure what they are.
Sara Seager (36:30.560)
We have a lot of thoughts as to the different types of planet it could be, but people don't
Sara Seager (36:34.300)
really know.
Lex Fridman (36:35.300)
I mean, what are your thoughts about what it could be?
Sara Seager (36:37.560)
Well, one thought, and this is more when we want to be rather than might be, is that these
Lex Fridman (36:43.260)
so called mini Neptunes, we call them, that they are water worlds, that they could be
Sara Seager (36:48.540)
scaled up versions of Jupiter's icy moons, such that they are planets that are made of
Lex Fridman (36:54.360)
more than half of water by mass.
Lex Fridman (36:57.400)
And what's the connection between water and life and the possibility of seeing that from
Lex Fridman (37:02.040)
a gas perspective?
Sara Seager (37:03.600)
Okay, so all life on Earth needs liquid water.
Lex Fridman (37:07.580)
And so there's been this idea in astronomy or astrobiology for a long time called follow
Sara Seager (37:12.400)
the water, find water, that will give you a chance of finding life, but we could still
Sara Seager (37:16.960)
zoom out and the community consensus is that we need some kind of liquid for life to originate
Lex Fridman (37:24.680)
and to survive because molecules have to react.
Lex Fridman (37:28.360)
You don't have a way that molecules can interact with each other.
Sara Seager (37:31.560)
You can't really make anything.
Lex Fridman (37:32.800)
And so when we think of all the liquids out there, water is the most abundant liquid in
Sara Seager (37:38.100)
terms of planetary materials.
Lex Fridman (37:39.640)
There really aren't that many liquids.
Sara Seager (37:40.920)
Like I mentioned, liquid rock, way too hot for life.
Sara Seager (37:44.640)
We have some really cold liquids, like almost gasoline, like ethane and methane lakes that
Sara Seager (37:49.600)
have been found on one of Saturn's moons, Titan.
Lex Fridman (37:52.880)
That's so cold though.
Lex Fridman (37:53.920)
And for exoplanets, we can't study really cold planets because they're just simply too
Lex Fridman (37:57.420)
dark and too cold.
Lex Fridman (38:00.480)
So we usually are just left with looking for planets with liquid water.
Lex Fridman (38:05.040)
And to your point, remember as we talked about how planets are less than a pixel in that
Sara Seager (38:12.920)
way to say, so we can't see oceans on planet.
Sara Seager (38:15.440)
We're not going to see continents and oceans, not yet anyway, but we can see gases in the
Sara Seager (38:19.520)
atmosphere.
Lex Fridman (38:20.520)
And if it's a small rocky planet, and this is going into some more detail, if we see
Sara Seager (38:26.840)
a small rocky planet with water vapor in the atmosphere, we're pretty sure that means there
Sara Seager (38:31.200)
has to be a liquid water reservoir because it's not intuitive in any way, but water is
Sara Seager (38:37.480)
broken up by ultraviolet radiation from the star or from the sun.
Lex Fridman (38:42.360)
And on most planets when water is broken up into H and O, the H, the hydrogen will escape
Sara Seager (38:47.600)
to space.
Sara Seager (38:48.600)
Because just like when you think of a child letting go of a helium filled balloon, it
Sara Seager (38:53.440)
floats upwards and hydrogen is a light gas and will leave from the planet.
Lex Fridman (38:58.860)
So ultimately if you have water, unless there's an ocean, like a way to keep replenishing
Sara Seager (39:03.220)
water vapor in the atmosphere, that water vapor should be destroyed by ultraviolet radiation.
Sara Seager (39:08.480)
Got it, so there's a, okay, so there's a need for liquid, I mean, I guess it was water.
Sara Seager (39:16.400)
Is water essential or are the liquids, I mean, the chemistry here is probably super complicated.
Lex Fridman (39:21.080)
It does, but you know, there's not an infinite number of liquids.
Sara Seager (39:24.160)
There's maybe like five liquids that can exist inside or on the surface of a planet.
Lex Fridman (39:28.680)
And water is the one that exists for the largest range of temperatures and pressures.
Lex Fridman (39:32.440)
And it's also the easiest type of planet for us to find and study is one with water vapor
Lex Fridman (39:37.360)
rather than a cold planet that has ethane and methane lakes.
Sara Seager (39:41.360)
What's your personal, in terms of solar systems and planets that you're most hopeful about
Sara Seager (39:48.760)
in terms of our closest neighbors that you kind of have a sense that there might be somebody
Sara Seager (39:57.320)
living over there, whether it's bacteria or somebody that looks like us.
Lex Fridman (40:02.840)
I'm hopeful that every star nearby has a planet.
Sara Seager (40:06.520)
That has some life.
Lex Fridman (40:07.520)
Because it almost has to for us to make progress.
Sara Seager (40:09.840)
We have to have that dream condition.
Lex Fridman (40:12.560)
So the dream condition is like life is just super abundant out there.
Sara Seager (40:16.760)
Yeah, the dream, yes, the dream condition is that life is super abundant and it's based
Sara Seager (40:21.280)
on the thought that if there is a planet with water and continents, that it also has the
Sara Seager (40:27.480)
ingredients for life and that the kind of base kernel thought is that if the ingredients
Lex Fridman (40:36.300)
for life is there, life will form.
Sara Seager (40:37.680)
Life will form.
Lex Fridman (40:38.680)
That's what we're holding on to.
Sara Seager (40:39.680)
With a relatively high probability.
Lex Fridman (40:41.880)
Yes, that's it.
Sara Seager (40:43.520)
Okay, let's go into land of speculation.
Lex Fridman (40:46.740)
What about intelligent life?
Sara Seager (40:49.600)
Us humans consider ourselves intelligent, surprisingly or unsurprisingly.
Lex Fridman (40:56.320)
Do you think about from your perspective of looking at planets from a gas composition
Sara Seager (41:02.560)
perspective and in general of how we might see intelligent life and your intuition about
Lex Fridman (41:10.400)
whether that life is even out there?
Sara Seager (41:12.400)
I think the life is out there somewhere.
Lex Fridman (41:14.760)
The huge numbers of stars and planets.
Sara Seager (41:17.520)
I like to think that life had a chance to evolve to be intelligent.
Sara Seager (41:21.480)
I'm not convinced the life is anywhere near here, only because if it's hard for intelligent
Sara Seager (41:26.620)
life to evolve, then it will be far away by definition.
Sara Seager (41:29.720)
Well, the sad thing is maybe from the artificial intelligence perspective is it makes me sad
Sara Seager (41:36.080)
there might be intelligent life out there that we're just not like the pathways of evolution
Sara Seager (41:43.160)
can go in all these different directions where we might not be able to communicate with it
Sara Seager (41:47.440)
or even know that or even detect its intelligence or even comprehend its intelligence.
Sara Seager (41:52.720)
I'm convinced cats are more intelligent than humans that we're just not able to comprehend
Sara Seager (41:59.480)
the measures, the proper measures of their intelligence.
Lex Fridman (42:04.980)
My dog is so funny.
Sara Seager (42:06.200)
He's a golden doodle.
Lex Fridman (42:07.200)
His name's Leo.
Sara Seager (42:08.280)
We joke that he's either a really dumb dog and sorry, he's not here to defend himself,
Lex Fridman (42:12.420)
but he's either really dumb or he's a super genius just pretending to be dumb.
Sara Seager (42:16.280)
Yeah.
Lex Fridman (42:17.280)
And it's possible he's a multidimensional projection of alien life here monitoring one
Sara Seager (42:25.400)
of the top scientists in the world trying to find aliens just to make sure that humans
Lex Fridman (42:33.480)
don't get out of hand.
Sara Seager (42:34.480)
That's funny.
Lex Fridman (42:35.480)
Oh, I'm definitely going to go in and ask him about that when I get home.
Sara Seager (42:39.960)
She's onto something.
Lex Fridman (42:40.960)
Yeah.
Lex Fridman (42:41.960)
What might we look for in terms of signs of intelligent life?
Sara Seager (42:46.580)
From your toolkit, do you think there are things that we might be able to use or maybe
Sara Seager (42:54.240)
in the next couple of decades discover that would be different than life that's like bacteria,
Lex Fridman (43:00.960)
that's primitive life?
Sara Seager (43:03.080)
I still love SETI, Search for Extraterrestrial Intelligence.
Sara Seager (43:06.320)
I like to hope that if there is a civilization out there, they're trying to send us a message.
Sara Seager (43:10.880)
I think, like, think about it, I don't know.
Lex Fridman (43:13.040)
What are your thoughts?
Sara Seager (43:14.040)
Like, if you think about our Earth, there's no structure we've built that intelligent
Lex Fridman (43:18.720)
civilizations could see from far away.
Sara Seager (43:20.680)
There's literally nothing, not even the Great Wall of China.
Lex Fridman (43:23.640)
And so to think, like, why would this other civilization build a giant structure that
Lex Fridman (43:27.700)
we could see?
Sara Seager (43:28.700)
Yeah, so with SETI, the idea is that we're both trying to hear signals and send signals,
Lex Fridman (43:33.760)
right?
Lex Fridman (43:34.760)
Well, we haven't sent one.
Sara Seager (43:35.760)
They call that METI, messaging.
Lex Fridman (43:37.240)
And there's a big kind of fear over METI, because do you want to tell them you're here?
Sara Seager (43:42.880)
It's kind of this, like, let's wait till they call us.
Lex Fridman (43:45.040)
Yeah.
Sara Seager (43:46.040)
It's like a dating game, you have to, like, how many days do I wait before I call, kind
Lex Fridman (43:51.960)
of thing.
Sara Seager (43:52.960)
Yeah.
Lex Fridman (43:53.960)
But the funny thing is, if no one's sending us a message, if everybody's only listening,
Lex Fridman (43:57.360)
how do you make progress?
Lex Fridman (43:59.920)
That's right.
Sara Seager (44:00.920)
And, I mean, but there's also, there's the Voyager spacecraft that we have these little
Lex Fridman (44:04.960)
pixels of robots flying out all over the place.
Sara Seager (44:09.960)
Some of them, like the Voyager, reach out really far.
Lex Fridman (44:13.320)
And they have some stuff on them.
Sara Seager (44:15.200)
Okay, I just...
Sara Seager (44:16.200)
We do, we have the Voyager, but they're not really going anywhere in particular.
Lex Fridman (44:19.160)
And they're moving very, very slowly on a cosmic scale.
Lex Fridman (44:21.960)
Yeah.
Lex Fridman (44:22.960)
And me saying they're far is kind of silly.
Lex Fridman (44:24.760)
Yeah.
Sara Seager (44:25.760)
It's all relative in astronomy.
Lex Fridman (44:26.760)
It's all relative.
Sara Seager (44:27.760)
Yeah.
Lex Fridman (44:28.760)
Yeah.
Sara Seager (44:29.760)
I just...
Lex Fridman (44:30.760)
So from the, if you look at Earth from an alien perspective, from visually and from
Sara Seager (44:36.320)
gas composition, I wonder if it's possible to determine the degree of maybe productive
Lex Fridman (44:44.880)
energy use.
Sara Seager (44:45.880)
I wonder if it's possible to tell, like, how busy these Earthlings are.
Lex Fridman (44:51.240)
Well, let's zoom out again and think about oxygen.
Lex Fridman (44:55.720)
So when cyanobacteria arose like billions of years ago and figured out how to harness
Sara Seager (45:00.200)
the energy of the sun for photosynthesis, they reengineered the entire atmosphere.
Sara Seager (45:05.240)
20% of the atmosphere has oxygen now.
Lex Fridman (45:09.080)
Like that is a huge scale.
Sara Seager (45:11.040)
You know, they almost poisoned everything else by making this, what was apparently very
Lex Fridman (45:15.080)
poisonous to everything that was alive.
Lex Fridman (45:17.400)
But imagine...
Lex Fridman (45:18.400)
So are we doing anything at that scale?
Sara Seager (45:19.400)
Like, are we changing anything at like 20% of the Earth with a giant structure or 20%
Lex Fridman (45:23.600)
of this or 20% of that?
Sara Seager (45:24.840)
Like we aren't actually.
Lex Fridman (45:26.200)
Yeah.
Sara Seager (45:27.200)
Yeah.
Lex Fridman (45:28.200)
That's humbling to think that we're not actually having that much of an impact.
Sara Seager (45:32.400)
I know.
Lex Fridman (45:33.400)
But we are because in a way we're destroying our entire planet.
Lex Fridman (45:35.440)
But it's humbling to think that from far away, people probably can't even tell.
Lex Fridman (45:40.520)
But from the perspective of the planet, when we say we're destroying, you know, global
Sara Seager (45:45.000)
warming, all that kind of stuff, what we really mean is we're destroying it for a bunch of
Lex Fridman (45:51.320)
different species, including humans.
Lex Fridman (45:54.040)
But like, I think the Earth will be okay.
Sara Seager (45:55.640)
Oh, the Earth will be, the Earth will remain, whatever happens to us, the Earth will still
Sara Seager (46:00.840)
be here.
Lex Fridman (46:01.840)
And it'll still be difficult to detect any difference.
Sara Seager (46:03.800)
Like it's sad to think that if humans destroy ourselves, except potentially with nuclear
Lex Fridman (46:09.560)
war, it'd be hard to tell that anything even happened.
Sara Seager (46:12.280)
Yeah.
Lex Fridman (46:13.280)
It's hard to tell from far away that anything happened.
Lex Fridman (46:15.800)
What about, what are your thoughts now?
Lex Fridman (46:17.680)
This is really getting into speculation land.
Sara Seager (46:21.760)
You've mentioned exoplanets were in the realm of, you know, this is beautiful edge between
Lex Fridman (46:28.220)
science and science fiction.
Sara Seager (46:31.600)
That some of us, a rare few are brave enough to walk, I think in academia, you were brave
Lex Fridman (46:37.940)
enough to do that.
Sara Seager (46:39.880)
I think in some sense, artificial intelligence sometimes walks that line a little bit.
Sara Seager (46:47.360)
There is so much excitement about extraterrestrial life and aliens in this world.
Sara Seager (46:52.760)
I mean, I don't know what, how to comprehend that excitement, but to me, it's great to
Sara Seager (46:59.600)
see people curious because to me, extraterrestrial life and aliens is at the core, a scientific
Sara Seager (47:06.800)
question.
Lex Fridman (47:08.400)
And it's almost looks like people are excited about science.
Lex Fridman (47:11.240)
They're excited by discovery, discovery, right?
Lex Fridman (47:16.020)
And then the possibility that there's alien life that visited earth or is here on earth
Sara Seager (47:21.360)
now is, is a excitement about discovery in your lifetime, essentially.
Lex Fridman (47:29.040)
I mean, what do you make, what do you make of that?
Sara Seager (47:33.180)
There's recent events where DARPA or DOD released footage of these unmanned aerial phenomena.
Lex Fridman (47:44.280)
They're calling them now UAP.
Sara Seager (47:46.240)
They got everybody like super excited.
Lex Fridman (47:48.160)
Like maybe there is like what, what, what's, what's here on earth.
Lex Fridman (47:52.220)
Do you follow the, this world of people who are thinking about aliens that are already
Lex Fridman (47:58.880)
here or have visited?
Sara Seager (48:00.360)
I don't really follow it.
Lex Fridman (48:01.360)
They follow me.
Sara Seager (48:02.360)
Because in this field, if you're a scientist of any kind, you get, people contact us, me.
Sara Seager (48:11.080)
There's a lot of them about, Hey, I have stuff you should see, Hey, the aliens are already
Sara Seager (48:15.680)
here.
Lex Fridman (48:16.680)
I need to tell you about it.
Lex Fridman (48:17.680)
And I know there are people out there who really believe there's a psychology to it.
Lex Fridman (48:22.640)
There's a psychology to it and it's fascinating, but okay.
Lex Fridman (48:25.800)
So it's similar to artificial intelligence, but I still, but like you, I'm still enamored
Lex Fridman (48:29.200)
with the point that it is out there and that people believe so strongly.
Lex Fridman (48:32.560)
And that's so many people out there believe, believe.
Lex Fridman (48:37.600)
And I don't know, I I'm not as allergic to it as some scientists are because ultimately
Sara Seager (48:44.400)
if aliens showed up or do show up or have showed up you know, these are going to be
Lex Fridman (48:50.360)
very difficult to study scientific phenomena.
Sara Seager (48:55.320)
Like in, in fact, like going back to cats and dogs, like I just, I think we should be
Sara Seager (49:01.320)
more open minded about developing new tools and looking for intelligent life on earth
Sara Seager (49:08.440)
that we haven't yet found.
Sara Seager (49:10.360)
Or even understanding the nature of our own intelligence because it kind of is an alien
Sara Seager (49:15.160)
life form, the thing that's living, you know, in our skull.
Lex Fridman (49:19.040)
It's so true.
Lex Fridman (49:20.040)
And we don't understand consciousness.
Lex Fridman (49:21.040)
Yeah.
Sara Seager (49:22.040)
It's true.
Sara Seager (49:23.040)
We don't understand how biology is hard, you know, unpacking it and working it all out.
Sara Seager (49:28.480)
It's a stretch.
Lex Fridman (49:29.480)
And they say too that our thinking mind is like the tip of a pyramid and that everything
Lex Fridman (49:34.120)
else is happening under the hood and, but what is happening?
Lex Fridman (49:37.640)
But the thing with, so the typical scientist response to, you know, are there aliens here
Sara Seager (49:42.560)
is that we need to see major evidence, not like a sketchy picture of something.
Lex Fridman (49:50.000)
We need some cold hard evidence and we just don't have that.
Sara Seager (49:53.600)
That's exactly right.
Lex Fridman (49:54.600)
Yeah.
Lex Fridman (49:55.600)
But from my perspective, I admire people that dream and I think that's beautiful.
Sara Seager (50:00.080)
The thing I don't like, there's two sides of the, of the folks that probably listened
Sara Seager (50:05.200)
to this, this podcast is, oh, those that dream, I think is beautiful, that, that wander what's
Lex Fridman (50:12.160)
out there, what's here on earth.
Lex Fridman (50:14.140)
And then the other ones who are very conspiratorial and thinking that stuff is being hidden and
Lex Fridman (50:19.520)
it becomes about institutions.
Sara Seager (50:20.840)
Right, right, right.
Lex Fridman (50:21.840)
Okay.
Sara Seager (50:22.840)
I got it.
Lex Fridman (50:23.840)
I have a funny thing to talk about that.
Lex Fridman (50:24.840)
So one of my colleagues had a really good answer to that and it's not me saying this,
Lex Fridman (50:28.600)
so I can say this, but he said, look, he works with NASA, not at NASA.
Sara Seager (50:32.360)
He works with government, not in the government.
Lex Fridman (50:35.140)
It's kind of mean, but he'd say, trust me, they couldn't hide it if they tried.
Lex Fridman (50:37.640)
Do you know what I'm saying?
Lex Fridman (50:39.640)
Like, we're not smart enough or good enough.
Sara Seager (50:42.360)
Not we or not me or not you, but whoever to cover it up.
Lex Fridman (50:45.280)
It just, it's sort of a myth.
Sara Seager (50:47.960)
Yeah.
Sara Seager (50:48.960)
It makes it sad because the people at NASA, the people at MIT, the people in academia,
Sara Seager (50:57.040)
the people in these institutions and yes, even in government are often trying, they're
Lex Fridman (51:03.560)
like just curious descendants of apes.
Sara Seager (51:06.280)
They're just, they, they want to do good.
Lex Fridman (51:08.800)
They want to discover stuff.
Sara Seager (51:09.960)
They're not trying to hide stuff.
Sara Seager (51:11.480)
In fact, most of them would, in terms of leaks, would love to discover this and release this
Sara Seager (51:18.520)
kind of stuff.
Lex Fridman (51:19.520)
There's a, did you ever watch the show called The X Files?
Sara Seager (51:23.160)
Yeah.
Lex Fridman (51:24.160)
Scully and Mulder.
Sara Seager (51:25.160)
Yeah.
Lex Fridman (51:26.160)
And what I love actually, I used to put it up during my talks, my public talks.
Sara Seager (51:29.920)
There's a picture of a UFO or what looks like UFO and it says, I want to believe.
Lex Fridman (51:35.360)
So that's, that's where I think a lot of us are coming from.
Sara Seager (51:38.040)
I want to believe.
Lex Fridman (51:40.400)
And it's so great.
Lex Fridman (51:41.400)
And one time I put that up and this very, very nice couple approached me really nervous
Lex Fridman (51:46.040)
afterwards and they said, Hey, can we take you out for lunch sometime?
Lex Fridman (51:49.720)
And I said, sure.
Lex Fridman (51:50.720)
And they were like the nicest people.
Lex Fridman (51:52.740)
And just one of many who has an alien, alien abduction story and the woman, um, could never
Lex Fridman (51:59.000)
have kids.
Sara Seager (52:00.000)
They were older, but they didn't have kids, which for them was a real source of regret.
Lex Fridman (52:02.980)
But it was because the aliens who had abducted her had made it so that she couldn't have
Sara Seager (52:06.560)
kids.
Lex Fridman (52:07.560)
And she had apparently something implanted behind her ear, which was somehow unimplanted
Sara Seager (52:12.280)
later.
Lex Fridman (52:13.280)
And they're just so sincere and they're such a lovely couple and they just wanted to share
Sara Seager (52:18.480)
their story.
Lex Fridman (52:19.480)
That's a, that's a real, whatever that is, that's the real thing.
Sara Seager (52:23.640)
The mystery of the human mind is more powerful than any alien or, I mean, it's as interesting
Lex Fridman (52:30.720)
I think as the universe.
Lex Fridman (52:32.000)
And I think they're somehow intricately linked, maybe getting a sense of numbers.
Lex Fridman (52:38.840)
How many stars are there in, um, maybe, I don't know what the radius that's reasonable
Sara Seager (52:46.880)
to think about.
Sara Seager (52:47.880)
I don't know if the observable universe is like way too big to think about, but in terms
Sara Seager (52:52.360)
of when we think about how many habitable planets there are, what are the numbers we're
Lex Fridman (52:56.600)
working with in your sense?
Lex Fridman (52:58.960)
What are the scale?
Lex Fridman (52:59.960)
Honestly, the numbers are probably like billions of trillions of stars.
Sara Seager (53:03.760)
Yeah.
Sara Seager (53:04.760)
You know, in the UK, I think, I don't know if we do that here, but they will call a billion
Sara Seager (53:07.720)
trillion where you put like one billion followed by a trillion.
Lex Fridman (53:10.880)
Yeah.
Sara Seager (53:11.880)
It's kind of weird, but here, I don't even know how to say the number 10 to the 20.
Lex Fridman (53:14.960)
Like if you know what that is, that's one followed by 20 zeros.
Sara Seager (53:17.600)
That's a big number.
Lex Fridman (53:18.600)
We don't have a name for that number.
Sara Seager (53:20.220)
There's so many per star.
Lex Fridman (53:22.640)
I think we kind of mentioned this.
Sara Seager (53:23.840)
Is there a good sense, there's probably argument about this, but per star, how many planets
Lex Fridman (53:30.320)
are there?
Sara Seager (53:31.320)
We don't have that number yet per se, you know, we're not really there, but some people
Lex Fridman (53:35.640)
think that there's many planets per star.
Sara Seager (53:38.240)
There's this analogy of filling the coffee cup, like, you know, you don't usually just
Lex Fridman (53:43.840)
pour one drop, you fill it.
Lex Fridman (53:45.360)
And that planetary systems, we see stars being born that have a disc of gas and dust and
Lex Fridman (53:51.160)
that ultimately forms planets.
Lex Fridman (53:53.280)
So the idea, this kind of concept is that planets, so many planets form too many.
Lex Fridman (53:58.940)
And eventually some get kicked out and you're left with like a full planetary system, a
Sara Seager (54:02.680)
dynamically full system.
Lex Fridman (54:04.000)
And so there have to be a lot because so many form and a bunch survive.
Lex Fridman (54:08.080)
I mean, that makes perfect intuitive sense, right?
Lex Fridman (54:11.080)
Like why wouldn't that happen?
Sara Seager (54:12.880)
Right.
Lex Fridman (54:13.880)
Well, there's other thoughts too, though.
Sara Seager (54:16.340)
These big planets that are really close to the star, we think they formed far away from
Lex Fridman (54:20.720)
the star where there's enough material to form and they migrated inwards.
Lex Fridman (54:25.220)
And some of these planets migrating inwards due to interaction with other planets or with
Lex Fridman (54:28.600)
the disc itself, they may have cleared it out.
Lex Fridman (54:32.120)
And kicked other planets out of the system.
Lex Fridman (54:34.700)
So there's a lot of ideas floating around.
Sara Seager (54:36.540)
We're not entirely sure.
Lex Fridman (54:39.120)
And what about Earth like planets?
Sara Seager (54:41.440)
That's another level of uncertainty.
Lex Fridman (54:43.680)
It's a level of uncertainty.
Sara Seager (54:44.760)
If we think of an Earth like planet being an Earth around a sun in the same orbit, an
Sara Seager (54:51.440)
Earth like planet being an Earth sized planet in an Earth like orbit about a sun like star,
Sara Seager (54:55.800)
we're not there yet.
Lex Fridman (54:56.800)
You know, we're not able to detect enough of those to give you a hard number.
Sara Seager (55:00.760)
Some people have extrapolated.
Lex Fridman (55:03.080)
And they will say as many as one in five stars like our sun could be hosting a true Earth
Sara Seager (55:08.560)
like planet.
Lex Fridman (55:09.560)
Wow.
Sara Seager (55:10.560)
On the topic of space exploration, there's been a lot of exciting developments with NASA,
Sara Seager (55:15.280)
with SpaceX, with other companies successfully getting rockets into space with humans and
Sara Seager (55:23.680)
getting them to land back, especially with SpaceX.
Lex Fridman (55:27.920)
What are your thoughts about Elon Musk and SpaceX, Crew Dragon, while working with NASA
Lex Fridman (55:33.920)
to launch astronauts?
Lex Fridman (55:35.680)
What's your sense about these exciting new developments?
Sara Seager (55:39.720)
Well, SpaceX and other so called commercial companies are only good news for my field,
Sara Seager (55:46.200)
because they're lowering the cost of getting to space by having reusable rockets.
Sara Seager (55:50.600)
It's just been it's incredible.
Lex Fridman (55:52.200)
And we need cheaper access to space.
Lex Fridman (55:53.840)
So from a very practical viewpoint, it's all good.
Sara Seager (55:56.760)
Without getting people, there's this dream that we have to go to Mars, boots on Mars.
Sara Seager (56:01.520)
Boots on Mars.
Lex Fridman (56:03.960)
What do you think about that?
Sara Seager (56:04.960)
You mentioned probes.
Lex Fridman (56:06.080)
What's the value of humans?
Lex Fridman (56:08.560)
Is that interesting to you from both scientific and a human perspective?
Lex Fridman (56:13.880)
Human mostly.
Sara Seager (56:14.880)
I think it's such in our desire to explore because part of what it means to be human.
Lex Fridman (56:19.400)
So wanting to go to another planet and be able to live there for some time.
Sara Seager (56:23.440)
It's just just what it means to be human.
Sara Seager (56:26.520)
You know, oftentimes in science and engineering, big, huge discoveries are made when we didn't
Sara Seager (56:32.160)
intend to.
Lex Fridman (56:33.680)
So often this kind of pure exploratory type of research or this pure exploration research,
Sara Seager (56:37.720)
it can lead to something really important like the laser, we couldn't really live without
Lex Fridman (56:41.060)
that now.
Sara Seager (56:42.060)
At the grocery, you scan your foods, there's surgery that involves lasers, GPS, we all
Lex Fridman (56:46.860)
use our GPS.
Sara Seager (56:47.860)
We don't have GPS because someone thought, hey, it'd be great to have a navigation system.
Lex Fridman (56:53.120)
And so I do support, I do, I just, but I really think it comes primarily just from the desire
Sara Seager (56:58.480)
to explore.
Lex Fridman (56:59.480)
Do you think something, there's a lot of criticism and a lot of excitement about Mars.
Lex Fridman (57:06.380)
Do you think there's value in trying to go to put humans on Mars, first of all, and second
Lex Fridman (57:12.880)
of all, colonize Mars?
Lex Fridman (57:15.680)
Do you think there's something interesting that might come from there?
Lex Fridman (57:18.920)
I'm convinced there will be something interesting.
Sara Seager (57:20.680)
I just don't know what it is yet, but I don't think, I don't think having some commercial
Sara Seager (57:24.880)
value or value in the metric of something useful is really what's motivating us.
Lex Fridman (57:29.480)
So really, you see, exploration is a long term investment into something awesome that
Lex Fridman (57:33.640)
eventually will be commercial value.
Sara Seager (57:35.560)
I do actually.
Lex Fridman (57:36.560)
Yeah.
Sara Seager (57:37.560)
I do.
Lex Fridman (57:38.560)
So what about visiting, okay, I apologize, but Amy, there's an exciting longing to visit
Sara Seager (57:48.640)
Earth like planets elsewhere.
Lex Fridman (57:51.140)
So what's the closest Earth like planet you think is worth visiting and how hard is it?
Sara Seager (57:59.200)
Wow, it is very hard.
Sara Seager (58:01.560)
I mean, our nearest, call it Earth mass planet, it's orbiting a star very different from
Sara Seager (58:05.640)
our own sun, an M Dwarf star, a small red star, Proxima Centauri.
Lex Fridman (58:10.460)
It's over four light years away and we can't travel at the speed of light.
Sara Seager (58:15.340)
We can't even travel, I mean, it would take tens of thousands of years to get there with
Lex Fridman (58:18.640)
conventional methods.
Sara Seager (58:19.640)
So, you know, the movies like multigenerational, yeah, this movie Passenger, have you seen
Lex Fridman (58:23.920)
that movie?
Sara Seager (58:24.920)
Passenger.
Lex Fridman (58:25.920)
No.
Sara Seager (58:26.920)
It's about a big spaceship that is traveling to another planet and everyone's hibernating.
Sara Seager (58:30.400)
I won't give you the spoiler alert because one person wakes up and then it's kind of
Sara Seager (58:33.320)
a problem.
Lex Fridman (58:34.320)
Okay, got it.
Lex Fridman (58:35.320)
But yeah, the multigenerational ships, I mean, when you think about where we're headed as
Sara Seager (58:40.940)
a species, maybe we don't send people, maybe we end up sending raw biological materials
Lex Fridman (58:48.200)
and instructions to print out humans, it sounds kind of farfetched, but already we're printing
Sara Seager (58:54.640)
like liver cells in the lab and beating heart cells, we're starting to reconstruct body
Sara Seager (59:01.360)
parts.
Sara Seager (59:02.360)
I mean, the thing is, it is so hard to get to another planet that this thought of printing
Sara Seager (59:06.080)
humans or printing life forms actually could be easier.
Sara Seager (59:09.080)
Yeah, that's somehow so sad to think, to think of the idea that we would launch a successful
Sara Seager (59:16.680)
spaceship that has multigenerational, like non human life and it's going to reach other
Sara Seager (59:23.520)
intelligent life and by the time they figure out where it came from, human civilization
Sara Seager (59:30.120)
will be extinct.
Lex Fridman (59:31.120)
Wow.
Sara Seager (59:32.120)
Yeah, that is really, I mean, that's, so that's one, there's a, there's a tempting thing to
Lex Fridman (59:36.480)
think about.
Lex Fridman (59:37.480)
What are the possible trajectories?
Sara Seager (59:38.480)
So, you know, Elon keeps talking about multi planetary, us becoming multi planetary species.
Sara Seager (59:47.040)
I mean, sure, Mars is a part of that, but like the dream is to really expand outside
Lex Fridman (59:55.000)
the solar system.
Lex Fridman (59:57.080)
And it's, it's not clear, just like, as you said, like what the actual scientific engineering
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