Kind: captions
Language: en
the following is a conversation with
sarah seeger
a planetary scientist at mit known
for her work on the search for
exoplanets which are planets outside of
her solar system
she's an author of two books on this
fascinating topic
plus in a couple days august 18th her
new book
a memoir called the smallest lights in
the universe
is coming out i read it and i can
recommend it highly
especially if you love space and are a
bit of a romantic like
me it's beautifully written she weaves
the stories of the tragedies and the
triumphs of her life
with the stories of her love for and
research on
exoplanets which represent our hope to
find life
out there in the universe quick summary
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as a quick side note let me say that
extraterrestrial life
aliens i think represent our
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why we're here the possibility of this
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now
here's my conversation with sarah seeger
when did you first fall in love with the
stars i think i've always loved the
stars
one of my first memory is of the moon i
remember watching the moon
and i was in the car with my dad who my
parents were divorced and he was driving
me and my siblings to his house for the
weekend
and the moon was just following me just
had no idea why that was
yeah so like looking up at the sky and
there's this glowing thing
how do you make sense of the moon that
at that age at age at like age five
there's just no way you can
i think it's one of the great things
about being a kid it's just that
curiosity that that all kids have
you know i was thinking because there's
these uh
uh almost uh out there ideas of of that
our earth is flat
uh floating about on the internet and it
made me think you know when did i first
realize that
the earth is um like this ball
that's uh flying through empty space
i mean it's terrifying it's uh
awe-inspiring
i don't know how to make sense of it
it's uh it's hard because we live in our
frame of reference here on this planet
yeah it's nearly impossible none of us
are lucky to go to see the curvature of
earth
i mean do you remember when you realized
understood like the physics
like the layout of the solar system this
is it was it like
did you first have to take physics to
really uh
like high school physics to really take
that in i think it's hard to say
i had this book when i was a child it
was in french i grew up in canada where
french is
supposedly taught to all of us
english-speaking canadians
and it was this friend book in french
was about the solar system and i just
love flipping through it
it's hard to say how much you know you
or i understand when we're kids but it
was really a great book
what about the stars when did you first
learn about the stars
like i do have this very incredible
distinctive memory and again it had to
do with my dad he took us camping now my
dad was from
the uk and he was the type who you'd
find wearing a tie on weekends
so camping was not in his sphere his
comfort zone
we had a babysitter every summer we got
a baby we every summer we had a
babysitter
and one summer we had tom he was barely
older than we were he was 14 my brother
was 12. i would have been 11
or 10 maybe and we went camping because
tom said camping's the thing we should
we should try it and i just remember
i didn't aim to see the stars but i
walked out of my tent in the middle of
the night
and i looked up and wow
so many stars the dark night sky and all
those stars just like screaming at me
i just couldn't believe that honestly
like my first thought was this is so
incredible mind-blowing
like why wouldn't anyone have told me
this existed can anyone else see this
have you have you had an ex have you
experienced like that with anything
like yeah i've had that i mean i don't
know if
maybe you can tell me if it's the same
uh i've had that with robots
uh there's a few robots i've met where i
just fell in love with this like
is anyone else seeing this is anyone
else seeing that
here in a robot is our ability to
engineer some intelligent beings
intelligent beings that we could love
that could love us that we can interact
with
in some rich ways that we haven't yet
discovered
like uh almost like when you get a puppy
it needs to have a dog
and there's this uh immediate bond and
love
and on top of that ability to engineer
it
it was you know i had to just pause and
and hold myself i imagine i don't have
kids i imagine there's a magic to that
as well
or it's a totally new experience it's
like what
well yeah the stars though unlike kids
or the puppy it's only a good thing
so you felt you weren't terrified like
it's
to me when i look at the stars it's
almost paralyzingly scary
how little we know about the universe
how alone we are i mean somehow it feels
alone
i'm not sure if it's a it's just a
matter of perspective but it feels like
wow there's billions of them out there
and we know nothing about them and then
also immediately to me somehow mortality
comes into it
i mean how did that make you feel at
that time i think as a child without
articulating it i felt that same way
just like wow this is terrifying what's
out there like what is this
what does it mean about us here uh you
you're a scientist an exo world class
scientist planetary scientist
astronomer uh now i'm a bit of an idiot
who likes to ask silly questions so some
questions are a little bit in the realm
of speculation
almost philosophical because we know so
little
and one of the awesome things about your
work is you've actually put data and
real science behind some of the biggest
questions that we're all curious about
but nevertheless many of the questions
might be a little bit speculative
so on that topic uh just in your sense
do you think
we're alone in the universe human beings
do you think there's life out there well
lex the funny thing is is that as a
scientist i so don't even want to answer
that
you do you really don't i will answer
them yeah but i just loved you resisted
naturally yeah we naturally resist that
because we want numbers and hard facts
and not speculation but i do love that
question it's a great question and it's
one we all wonder about
but i have to give you the scientist
answer first yeah sure which is
we'll have the capability to answer that
question soon even starting soon
how do you define soon how do i define
science what do you so much happen in
the last 100 years
right right and there's a difference
right if it's 10 years or 20 years or
100 years yeah
there's a difference in that well soon
could be a decade
or two decades and then by the way
journalists usually don't like that or
the people want like tomorrow they want
the news but what it's going to take is
telescopes space telescopes or very
sophisticated ground or space telespace
telescopes to
let us study the atmospheres of other
planets far away and to look what's in
the atmospheres and to look for water
which is needed for life as we know it
to look for gases that don't belong that
we might attribute to life so we have to
do some really nitty-gritty
astronomy so the the promising way to
answer this question
scientifically is to look for hints of
life that's where like many of your
ideas come in
of what kind of hints why might we
actually see about this
right right that's exactly what we need
to do and i like the word you chose hint
because it's going to be a hint it's not
going to be a 100 percent yay we found
it
and then it will take future generations
to do more careful work to hopefully
even find a way to send a probe to these
distant exoplanets
and to really figure this out for us i
mean we'll talk about the details
those are fun but like uh back to the
speculation
zoomed out big pictures yes
i believe absolutely there is life out
there somewhere
because there the vastness of the
universe
is incredible it's so breathtaking when
we look at the night sky if you can go
to that dark sky
you can see you know many many hundred
or even
if you have good eyesight and you're
somewhere very dark you could see
thousands of stars
but in our galaxy we have hundreds of
billions of stars
and our universe has hundreds of
billions of galaxies
so think about all those stars out there
and even if planets are rare even if
life is rare
just because the number of stars is so
huge
things have to come together somewhere
someplace in our universe yeah it's so
amazing to think that somebody might be
looking up on another
planet in a distant galaxy
and get back to in our lifetime at least
the short term
we have to we only have the nearest
stars
to look at it's true that there are so
many stars
so many hosts for planets that might
have life but in the practical
question of will we find it it has to be
a star
quite close to earth like a few light
years tens of light years maybe hundreds
of light years
and by the way you've introduced me to a
tool of
eyes on exoplanets i think
that nasa has put together isolated
clinics that's it
software you guys that's so cool uh but
anyway uh
can you give a sense of like who our
neighbors are
like you said uh hundreds of light years
like how many stars are close by
at like what what's our neighborhood
like we're talking about
five ten stars that we might actually
have a chance
to zoom in on i'm talking about maybe a
dozen or two dozen
stars and those are that's with planets
that look
suitable for us to follow up in detail
for life
right one thing that's really exciting
in this field is that
the very nearest star to earth called
proxima centauri
it's part of the alpha centauri star
system cool name by the way yeah
approximately whoever names them
nearby okay but it sounds cool proxima
proxima centauri appears to have a
planet around it that's an earth map
about an earth mass planet
in the so-called habitable zone or the
goldilocks zone of the host star
so think about how incredible that is
like out of all the stars out there even
the very nearest star
has planets and has a planet of huge
interest to us
yeah okay so can we talk about that
planet what uh
uh what what does it mean to be maybe
possibly habitable habitable uh
you know what uh what is how does size
come into play
how does um you know what we know about
gases and what kind of things are
necessary for life
you know what are the factors that you
make you think that it's habitable
and by the way i mean maybe one way to
talk about that is
people know about the drake equation
which is
a very high level almost framework to
think about what is the probability that
correct me if i'm wrong that there's
life out there uh
and intelligent life i think i don't
know
but then the equation named after you
now
which i think nicely focuses in on the
more
achievable and interesting uh part of
that
question which is on whether there is
habitable
planets out there or how many i guess
right
so the funny thing is was one time i met
frank drake
and i asked if he minded if i took his
equation and kind of
revamped it for this new field of
exoplanet astronomy
he was totally cool with it he's he got
total approval well maybe uh
okay so i'm not sure if he'd actually
read the stuff about my equation but he
was cool with it he was
cool with it uh okay so i just said like
15 different things but
maybe can you tell from your perspective
what is the drake equation
and what is sorry the seeger equation
sure well the drake equation as you said
it's a framework
it's a description of the number of
civilizations out there
of intelligent beings that are able to
communicate with us by radio waves
so if you think of like if you think of
the movie contact you've seen contact
right
we're hoping to get we're listening in
actually it's an active field of
research
listening to other stars at radio
wavelengths hoping that some
intelligent civilizations are sending us
a message and the drake equation
came like at the start of that whole
field to put the factors down on paper
to sort of illustrate what is involved
to kind of estimating and there's no
real estimate or a prediction of how
many civilizations are out there
but it's a way to frame the question and
show you each term that's involved
so i took the drake equation and i
called it a revised drake equation
and i recast it for the search for
planets by more traditional astronomy
means
we're looking at stars looking for
planets looking for rocky planets
looking for planets that are the right
temperature for life
looking for planets that might have life
that outputs gases that we might detect
in the future
it's the same spirit of the drake
equation it's not going to give us any
magic numbers
so i'm going to say hey here's exactly
what's out there it's meant to kind of
guide guide
of where we're going although the jerk
equation did i mean the initial
equation proposed actual numbers for
those variables
oh yes the equation proposed numbers and
you can still
plug your own numbers in and there's
this really cute website that lets you
for both the drake and my revised
equation plug in some numbers and see
what you get
so yeah so okay so what are what are
i mean what are the variables but maybe
also what are like the critical
variables so in my equation i set out to
what are the numbers of
inhabited planets that show signs of
life by way of gases in the atmosphere
that can be attributed to life
i could just walk through the terms
that's super simple the first thing i
say is what are the number of stars
available and it's not that
those trillions and trillions of stars
everywhere it's what are available to
like a specific search
and so for example the mit led nasa
mission tess
is surveying the sky looking for all
kinds of planets but it can also
it also has stars it has about 30 000
red dwarf stars
so we just take a number of stars that a
given survey can access
so that's what the number of stars is
then i wanted to know what kind of stars
are
uh quiet a quiet i called it
a fraction of those stars that is quiet
in the case of tess the way it's looking
for planets
is planets that transit the star they go
in front of the star as seen from the
telescope
but it turns out that some stars are
very active they're variable
and they brighten and dim with time and
that interferes with our observation
i apologize to interrupt so it's a
transiting planet so you're
really looking for a black blob
essentially that blocks the light
we're looking for a black blob that
blocks light and then trying to say
something about the size of the planet
uh from the frequency of that black
blobs appearance and the size of that
black blob that kind of thing yeah but
let's just say that
out of all the stars there are
accessible to whatever telescope some of
them are just bad
for whatever reason you're not gonna be
able to find planets around them so i
need to know the fraction
of those that are that are good so again
we have the number of stars the fraction
of them that we can actually find
planets around
um and by the way is our sun set one
such
is is our sun quiet our sun is quiet
okay
so i have actually two terms one
describes how quiet they are and one is
if we can find a planet around that star
these transiting planets for example
not all planets transit because the
planet would have to be orbiting that
star
in this kind of plane as viewed from you
but if a star is for example orbiting in
the plane of the sky it will never
transit
it will never go in front of the star so
in that case we have to have a fraction
that
takes into account that kind of
geometric
factor and hopefully it's right i mean
you can assume that it's uniformly
distributed hopefully yes we can assume
and there's evidence that it's uniformly
distributed yes
so then the next so all of these factors
so far
number of stars accessible to whatever
telescope you're thinking about
how many stars are quiet fractional
stars that are quiet fraction
that are observable in this case for the
geometric factor
those are all things we can measure and
there's one more term in the seeger
equation we can measure
i call it fraction of planets in the
habitable zone
because believe it or not we have a
handle on that for a
certain set of stars we know from our
the kepler space telescope that operated
for a number of years
we have estimates for how many planets
are in the so-called habitable zone of
the host star for a certain type of star
so all those we have measurable and then
like the drake equation itself there are
some terms we can
not measure and those ones i call them
fl
fraction of all those planets that have
life on them
because we don't know what that is and
fs i called for spectroscopy
the fraction that have we can use our
telescope and instrument tools to
look for light actually fs was the ones
that the planets that
that have life that actually gives off a
gas a useful gas that might accumulate
in the atmosphere
so we could eventually observe it uh
how do the fl and fs interplay so these
are separate terms
separate terms and so so for example
you could imagine so for example you
could imagine life
like us humans we breathe out carbon
dioxide
but our planet earth we already have a
lot of carbon dioxide on it
well we have hundreds of parts per
million but it has a really strong
signal
so us humans breathing out carbon
dioxide it's not helpful for any
intelligent beings that are looking back
at earth
because there's already a lot of there's
already enough carbon dioxide we're not
adding to it
so if there is life on a planet and it's
outputting a boring gas that's not
helpful for us to uniquely
identify as being made by life versus
just being there anyway
then it's not helpful so i separated
those two terms out
soon i think we'll have evidence that
planets that can support life
at least are common so
okay this is such an awesome topic i
have a million questions uh
what okay i know it's a little bit of
speculation but what's your sense about
that
uh i think fs which is like
that uh life would produce
interesting gases that would be able to
detect like is there
one is there scientific evidence and and
second is there some intuition around
life producing gases detectable hints in
terms of
chemistry so interestingly enough that
entire question
relates to i'm gonna say almost my
life's work yeah the work i'm doing now
and the work i'm doing for the next 20
years
and i wish i could give you a concrete
number like one percent like on
the worst days it's one percent let's
say in my mind
you know in the best days it's like 80
and i could actually go into
a lot of detail here but i'll just give
you the simplest things
so first of all we make an assumption
that like us
and our life here on earth life uses
chemistry
so we use chemistry because we eat food
we breathe air and we have metabolism
that
to break down food to get energy to
store energy
and then ultimately to use it and all
life here has some kind of byproduct in
doing all that some kind of waste
product that goes into the atmosphere
so i like to think that life everywhere
uses chemistry
some people have imagined like uh let's
imagine like a windmill
like mechanical energy just getting
energy and using it without storing it
and if there was life like that it might
not need to output a gas
so we make this basic assumption of
chemistry that's the first thing
the second more complicated thing that i
and my team work on is what happens to
the gas once it is
produced by life it goes into the
atmosphere and a lot of gas
is just destroyed immediately actually
by
ultraviolet radiation or by oxygen
oxygen's incredibly
um destructive to a lot of gases so the
gas can
be produced by life but it could be just
completely destroyed by its environment
i guess we should pause on that that
you mentioned your life's work i mean
this is just a beautiful idea
that uh it's kind of paralyzing when you
look out there and you wonder is there a
life out there
a b is it's the first paralyzing
actually before i encountered your work
i feel like an idiot
but you know uh it feels like there's no
tool to answer that question
and then what you kind of provided
is this cool idea that it might be
possible to answer that by looking at
the gases i mean that's a really
interesting that's a beautiful idea and
uh yeah so we could just pause on like
that's as a powerful tool i think
that uh to build the intuition wrong
because i was totally clueless about it
and that was kind it's kind of exciting
i mean i'm sure there's a
folks probably early on in your life uh
who were very skeptical about this
notion well
maybe i'm not sure but it's generally
you would want to be skeptical it's like
well
all these kinds of other things could
generate gases you know all those
oh that's so true and that's a big part
of this growing field is how to
make sure that this gas isn't produced
by another effect
but i do want to you know again pausing
on that and going back a bit
it's incredible to think but like at
least almost 100 years ago
there's a record of someone talking
about the idea of a gas being an
indicator of life elsewhere oh
that idea was floating about it was
totally floating about
and it comes down to oxygen which on our
planet fills our atmosphere
to 20 by volume and you know we rely on
oxygen to breathe
you know when they you hear about the
people on mount everest running out of
air
they're really running out of oxygen
well they're running out of oxygen
because the air is getting thinner
as you they climb up the mountain but
without plants and bacteria there's
plants that bacteria that also
photosynthesizes and produces oxygen as
a waste product without those we would
have virtually no oxygen
our atmosphere would be devoid of oxygen
so yeah what uh if you were to analyze
uh earth is oxygen the strong indicator
here
oxygen is a huge indicator and that's
what we're hoping that there is an
intelligent civilization
not too far from here around a planet
orbiting a nearby star
with the kind of telescopes we're trying
to build and they're looking back at our
sun and they've seen our earth and they
see oxygen and they
they probably won't be like 100.00 sure
that there's life making it
but if they go through all the possible
scenarios they'll be left with a pretty
strong hint
that there's life here yeah okay but how
do you detect
that type of gases that are on the
planet
from a distance and that's going back to
that
that's what people were skeptical about
when i first started working on
exoplanets long time ago
people didn't believe we would ever ever
ever study an exoplanet atmosphere of
any kind
and now dozens of them are studied
there's a whole field of people
hundreds of people working on exoplanet
atmospheres actually wow
but first there was a point where people
didn't even know there was exoplanets
right when was the first exoplanet
detected the first exoplanet around a
sun-like star anyway was detected in the
mid-1990s
that was a big deal i kind of vaguely
remember that well at the time it was a
big deal but it was also incredibly
controversial
because in exo you know planets
we only had one example of a planetary
system our own solar system
and in our solar system jupiter our big
massive planet
is really far from our star and this
first exoplanet around a sun-like star
was incredibly close to its star it's
star so close that people just couldn't
believe it was a planet actually
so maybe zoom out what the heck is an
exoplanet
an exoplanet is our name like is the
name that we call
a planet orbiting a star other than our
sun
right extra solar i guess is the number
you can call it extrasolar
exoplanet is simpler but i think it's
worth pausing to remember
that each one of those stars out there
in our night sky is the sun
right and you know our sun has planets
mercury venus earth mars etc
and so for a long time people have
wondered do those other stars or other
suns have planets
and they do and it appears that nearly
every star has a planet has a planet we
call exoplanet
and there are thousands of known
exoplanets already so there's already
yeah like there's so many things about
space
that it's hard to put in into one's
brain
because it starts filling it with awe so
yeah if you visualize
the fact that the stars that we see in
the sky
aren't just stars they're like they're
sons
and they very likely as you're saying
will have planets around them there's
all these planets
roaming about in this like dimly lit
darkness with potentially uh
life i mean it's just mind-blowing but
um maybe can you
give a brief like history of
and like of discovering all the
exoplanets so there's no exoplanets in
the 90s
and then there's a lot of exoplanets now
so how did that come about so many
planets
how did it come about well maybe another
way to ask is what is the methodology
that was used to discover them i can say
that
but i'd like to just say something else
first where so in exoplanets
you know the line between what is
considered completely crazy
and what is considered mainstream
research legit is constantly shifting
this is awesome yeah so before when i
started on exoplanets
it was still sketchy like it wasn't
considered a career or a thing
a place where you should be investing
and right now
now today it's so many people are
working in this field
a good i don't know at least a thousand
probably more i don't know if that
sounds like a lot to you but it's a lot
no it's a legitimate field of inquiry
yeah legitimate field of increase and
what's helped us is everything that's
helped
everyone else it's software it's
computers it's hardware
it's like our phones you have a
fantastic detector in there like they
didn't always have that i don't know if
you remember
the so-called olden days we didn't have
digital cameras we had film
you take a film camera you send the film
away and eventually it comes back and
then you see your pictures
and they could all be horrible yeah so
yeah it sent me digital
it just changed everything data changed
everything yeah and so one thing that
really helped exoplanets were detectors
that were very sensitive because when
we're looking for
this the transiting planets what we're
doing is we're monitoring a star's
brightness as a function of time
it's like click taking a picture of the
stars every few seconds
or minutes and we're measuring the
brightness of a star
like every frame and we're looking for a
drop in brightness that's characteristic
of a planet going in front of the star
and then finishing its so-called transit
and to make that measurement we have to
have precise detectors
and uh the the detectors that are making
the measurement
can you do it from earth is it uh are
they floating about in space
like what kind of telescope both so on
the ground people are using telescopes
small telescopes that are almost just
like a glorified telephoto lens
and they're looking at big swaths of the
sky and from the ground
people can find giant planets like the
size of jupiter so it's about 10 to 12
times the size of earth
we can find big planets because we can
reach about
one percent precision so i'm not sure
how much technical you want to get but
well yeah well how many pixels are we
talking about like what uh
you mentioned phones there's a bunch of
uh megapixels
i think so for exoplanets you want to
think about it as like a pixel or less
than a pixel we're not getting any
information
but to be more technical our telescope
you know spreads the light out over many
pixels
but we're not getting information we're
not tiling the planet with pixels
it's just like a point of light or in
most cases we don't even see the planet
itself just the planet's effect on the
star
but another thing that really helped was
computers because
transiting planets are actually quite
rare i mean they don't all go in front
of their star right
and so to find transiting planets we
look at a big part of the sky at once or
we look at
tens of thousands or hundreds of
thousands or even in some cases millions
of stars at one time
and so you know you're not going to do
this by hand going through a million
stars
counting up the brightness we so we have
computer software and
computer code that does the job for us
and looks for
a you know counts the brightness and
looks for a signal
that could be due to a transiting planet
and you know i just finished a job
called uh deputy science director for
the mit led nasa mission test
and it was my purview to make sure that
we got the
planet candidates the transiting light
curves out to the community so people
could follow them up
and figure out if they're actual planets
or false positives
so publish the data so that people could
just uh yeah publish data all the
all the data scientists out there could
crunch and see if they can exactly
they can discover something and in fact
the nasa policy for this mission
is that all the data becomes public as
soon as possible
so anyone could act it's not as easy as
it sounds though to download the data
and look for planets
but there is a group called
planethunters.org and they take the data
and they actually crowdsource it out to
people to look for planets yeah and they
often find
fine signals that our computers and our
team missed so
we mentioned exoplanets what about earth
like
or i don't know what the right
distinction is if is it habitable or is
it earth-like planets
but what are those different categories
and how can we tell the difference and
detect each
right right so we're not at earth-like
planets yet
all the planets we're finding are so
different from
what we have in our solar system they're
just easier planets to find but like
in which way for example there could be
a jupiter-sized planet where an earth
should be
we find planets that are the same size
as earth
but are orbiting way closer to their
star than mercury is to our sun
and they're so close that because close
to a star means they also orbit faster
and some of these hot super earths we
call them
their year their time to go around their
star is less than a day
and they're heated so much by their star
they're heated so much by the star
we think the surface is hot enough to
melt rock so instead of
running out by the bay or the river
you'll have like liquid lava
there'll be liquid lava lakes on these
planets we think
and life can't survive way too hot
the molecules for life would just be
molecules needed for life just wouldn't
wouldn't be able to survive those
temperatures
we have some other planets one of the
most mysterious things out there
factoid if you will is that the most
common type of planet we know about so
far
is a planet that's in between earth and
neptune size
it's two to three times the size of
earth and we have no solar system
counterpart of that planet
that is like going outside to the forest
and finding some kind of
creature or animal that just no one has
ever seen before and then discovering
that is the most common thing out there
and so we're not even sure what they are
we have a lot of thoughts as to the
different types of planet it could be
that people don't really know i mean
what are your thoughts about what it
could be
well one thought and this is more when
we want to be rather than might be
is that these so-called mini neptunes we
call them
that they are water worlds that they
could be scaled up versions of jupiter's
icy moons
such that they are planets that are made
of more than half of water
by mass so yeah and what's the
connection between water and life
and the possibility of seeing that from
a gas perspective
okay so all life on earth needs liquid
water
and so there's been this idea in
astronomy or astrobiology for a long
time called follow the water
find water that will give you a chance
of finding life
but we could still zoom out and the kind
of the community
consensus is that we need some kind of
liquid
for life to originate and to survive
because molecules have to react
if you don't have a way that molecules
can interact with each other
you can't really make anything and so
when we think of all the liquids out
there water is the most abundant
liquid in terms of planetary materials
there really aren't that many liquids
like i mentioned liquid rock way too hot
for life
we have some really cold liquids like
almost gasoline like ethane and methane
lakes that have been found on
one of saturn's moons titan that's so
cold though
and for exoplanets we can't study really
cold planets because they're just simply
too
dark and too cold so we usually so we're
usually just left with
looking for planets with liquid water
and
to your point it's remember as
we talked about how planets are less
than a pixel
in in that way to say so we can't see
oceans on planet we're not going to see
continents and oceans not yet anyway
but we can see gases in the atmosphere
and if it's a small rocky planet
and this is going into some more detail
it's a small if we see a small rocky
planet with water vapor in the
atmosphere
we're pretty sure that means there has
to be a liquid water reservoir
because it's not intuitive in any way
but water
is broken up by ultraviolet radiation
from the star
or from the sun and on most planets
when water is broken up into and o the h
the hydrogen will escape to space
because just like when you think of
a child letting go of a helium-filled
balloon it
floats upwards and hydrogen's a light
gas and will leave from earth
leave from the planet so ultimately if
you have water
unless there's an ocean like a way to
keep replenishing water vapor in the
atmosphere that water vapor should be
destroyed
by ultraviolet radiation got it so
there's a
okay so there's a need for liquid
i mean i guess what is water well is
water essential is
other liquids i mean the chemistry here
is probably super complicated there's
not it does but you know there's not an
infinite number of liquids
right there's maybe like five liquids
that can exist inside or on the surface
of a planet
and water is the one that exists for the
largest range of temperatures and
pressures
and it's also the easiest type of planet
for us to find and study as one with
water vapor
rather than a cold planet that has
ethane and methane lakes
what's your personal in terms of solar
systems
and planets that you're most hopeful
about uh in terms of our closest
neighbors
that you kind of have a sense that
there might be uh somebody living
over there whether it's bacteria or
somebody that looks like us
i'm hopeful that every star nearby has
has a planet has some life because it
almost has to for us to make progress
we have to have that dream condition so
the dream condition is like
life is just super abundant out there
yeah the dream
yes the dream condition is that life is
super abundant and it's based on
the thought that if there is a planet
with water
and continents that it also has the
ingredients for life and that
the kind of base does the base
the base kernel thought is that if the
ingredients for life is there life will
form
that's what we're holding on with the
relatively high probability
yes that's that's it okay let's go into
land of speculation
uh what about intelligent life
uh us humans consider ourselves
intelligent surprisingly
or unsurprisingly do you think about
from your perspective of looking at
planets from a
gas composition perspective
and in general of how we might see
intelligent life
and uh your intuition about whether that
life is even out there
i think the life is out there somewhere
the huge numbers of stars and planets
i like to think that life had a chance
to evolve to be intelligent
i'm not convinced the life is anywhere
near here only because
if it's hard for intelligent life to
evolve then it will be far away by
definition
well the sad thing is uh maybe from the
artificial intelligence perspective
is it makes me sad there might be
intelligent life out there that we're
just not
like the pathways of evolution
can go in all these different directions
where we might not be able to
communicate with it
or even know that or even detect its
intelligence or even comprehend
its intelligence yeah convince cats are
more intelligent than humans
that that we're just not able to
comprehend
the the measures the the proper measures
of their intelligence
my dog is so funny he's the golden
doodle his name's leo
we joke that he's either a really dumb
dog and so he's not here to defend
himself but he's either really dumb
or he's a super genius just pretending
to be dumb yeah
i mean it's possible he's he's a
multi-dimensional projection
of alien life uh here monitoring
uh one of the you know one of the top
scientists in the world trying to find
aliens just to make sure
just just to make sure that humans don't
get out of hand that's funny oh
i'm definitely going to go in and ask
him ask him about that
ask him about that he's on to something
yeah what might we
look for in terms of signs of
intelligent life
from your toolkit do you think there are
things
that we should we might be able to use
or maybe in the next couple of decades
discover
that would be different than life that's
like bacteria
that's primitive life i still love seti
search for extraterrestrial intelligence
i like to hope that if there is a
civilization out there they're trying to
send us a message
i think like think about it i don't know
what are your thoughts like if you think
about our earth
there's no structure we've built that
intelligent civilizations could see from
far away
there's literally nothing not even the
great wall of china and so to think like
why would this other civilization
build a giant structure that we could
see
yeah so with seti the idea is that we're
both trying to hear signals and send
signals right
we haven't sent one they call that medi
messaging and there's a big kind of
fear over medi because do you want to
tell them you're here
it's kind of this like let's wait till
they call us yeah
so uh we should have a dating game we
have to
like how how many days do i wait before
i call kind of thing
yes it and so but the funny thing is if
no one's sending us a message if
everybody's only listening
how do you make progress that's right
and so i mean but there's also
there's the voyager spacecraft so we we
have these little pixels of
uh robots flying out all over the place
some of them like the voyager reach out
really far
and they have some stuff stuff on them
okay i just
we do we have the voyager but they're
not really going anywhere in particular
and they're moving
very very slowly on a cosmic scale yeah
and let me say
they're far is kind of silly because
yeah it's all relative in astronomy it's
all relative yeah
yeah i just i so from uh if you look at
earth from an alien perspective
from visually and from gas composition
i wonder if it's possible to determine
the degree
of maybe um productive
energy use i wonder if it's possible to
tell
like how busy these earthlings are well
let's zoom out again and think about
oxygen
so when cyanobacteria arose like
billions of years ago and figured out
how to harness the energy of the sun for
photosynthesis
they re-engineered the entire atmosphere
of the atmosphere has oxygen now like
that is a huge scale you know they
almost poisoned everything else
by making this what was apparently very
poisonous to everything that was alive
but imagine so are we doing anything at
that scale like are we changing anything
in like 20
of the earth with a giant structure or
20 of this or 20
of that like we aren't actually yeah
yeah that's
that's uh that's humbling to think that
we're not actually having that much of
an impact i know
but we are because in a way we're
destroying our entire planet but it's
humbling to think that from far away
people probably can't even tell but from
the perspective of the planet
when we say we're destroying you know
global warming all that kind of stuff
um what we really mean is we're
destroying it
for a bunch of different species
including humans
but like i think the earth will be okay
oh the earth will be the earth will
remain
whatever whatever happened to us the
earth will still be here and it'll still
be difficult to detect any difference
like it's sad to think that
if humans destroy ourselves except
potentially when you clear war
it'd be hard to tell that anything even
happened yeah it will be hard to tell
from far away
that anything happened what about what
are your thoughts now this is really
getting into speculation land there
you've you've mentioned exoplanets were
in the realm of you know there's this
beautiful edge
between science and science fiction
that uh some of us a rare few are brave
enough to walk
i think in academia you were brave
enough to do that
i think in some sense artificial
intelligence sometimes walks that line
a little bit um there is so much
excitement about
extraterrestrial life and aliens in this
world
i mean i don't know what how to
comprehend
that excitement but to me it's great to
see people
curious because to me extraterrestrial
life and aliens
is at the core a scientific question
and it's almost looks like people are
excited about science they're
excited by discovery discovery right
and then the possibility that there's
alien life that visited earth
or is here on earth now is
is uh excitement about discovery
in your lifetime essentially i mean
what do you make what do you make of
that there's recent events where darpa
um or dod released footage
of uh these um unmanned
aerial phenomena they're calling them
now uap
they got everybody like super excited
like maybe there is like what
what what's what's here on earth uh do
you follow
the this world of people who are
thinking about
aliens that are already here or have
visited i don't really follow it they
follow me i'd say
because in this field if you're a
scientist of any kind you get
the people contact us me
there's a lot of them about hey i have
stuff you should see
hey the aliens are already here i need
to tell you about it
and i know there are people out there
who really believe
there's a psychology to it there's a
psychology to it and
it's fascinating but okay so it's
similar to artificial intelligence but i
still but like you i'm still enamored
with the point that it is out there
and that people believe so strongly and
that so many people out there
believe i believe and uh
i don't know i i i'm not as allergic to
it as
some scientists are because ultimately
if aliens
showed up or do show up or have showed
up
you know these are going to be very
difficult to study scientific phenomena
like in fact like going back to cats and
dogs
like i just i think we should be more
open-minded about
uh developing new tools and looking for
intelligent life on earth that we
haven't yet found
or even understanding the nature of our
own intelligence
because it kind of is an alien life form
the thing that's living
you know in our skull it's so true when
we don't understand consciousness
yeah it's true we don't understand how
biology is hard
you know unpacking it and working it all
out it's a stretch and they say too that
our thinking mind is like the tip of the
pyramid
that everything else is happening under
the hood and but what is happening
but the thing with so the typical
scientists response to you know are
there aliens here
is that we need to see major evidence
not like a sketchy picture of something
we need some cold hard evidence and we
just don't have that
that's exactly right but from my
perspective i
admire people that dream and i think
that's beautiful
the thing i don't like there's two sides
of the of the folks
uh that probably listen to this this
podcast is oh
those that dream i think is beautiful
that uh
that wonder what's out there what's here
on earth and then the other ones
who are very conspiratorial in thinking
that stuff is being hidden
right becomes about institutions okay
i have a funny thing to tell you about
that so one of my colleagues had a
really good answer to that
and it's not me saying this so i can say
this but he said look he works with nasa
not at nasa he works with government not
in the government
it's kind of me but he'd say trust me
they couldn't hide it if they tried
do you know what i'm saying like
everybody we're not we're not smart
enough or good enough
not we or not me or not you but whoever
to cover it up it just
it's sort of a myth yeah
it makes it sad because um the people at
nasa the people at mit
the people in academia the people in
these institutions
and yes even in government are often
trying they're like just curious
descendants of apes
they're just they they want to do good
they want to discover stuff they're not
trying to hide stuff
in fact most of them would in terms of
leaks
would uh love to discover this and
release this kind of stuff
and there's a did you ever watch this
show called the x-files
yeah scully and mulder yeah and what i
love actually i used to put it up during
my talks
my public talks there's a picture of a
ufo or what looks like ufo and it says
i want to believe so that's
that's where i think a lot of us are
coming from i want to believe
and it's so great and one time i put
that up
and this very very nice couple
approached me really nervous afterwards
and they said hey can we take you out
for lunch sometime
and i said sure and they were like the
nicest people
and just one of many who has an alien
alien abduction story
and the woman um could never have kids
they were older but they didn't have
kids which for them was a real source of
regret but it was because the aliens who
had abducted her had made it so that she
couldn't have kids
and she had apparently something
implanted behind her ear which was
somehow unimplanted later
and they were just so sincere and
they're such a lovely couple
they just wanted to share their story
that's that's a real
whatever that is that's the real thing
the mystery of the human mind
right is more powerful than any alien
or i mean it's uh as interesting i think
as the universe and
i think they're somehow intricately
linked
maybe getting a sense of numbers
how many stars are there in
maybe i don't know what