Kind: captions
Language: en
the following is a conversation with avi
loeb an astrophysicist
astronomer and cosmologist at harvard he
has authored
over 800 papers and written eight books
including his latest called
extraterrestrial
the first sign of intelligent life
beyond earth it'll be released in a
couple of weeks
so go pre-order it now to show support
for what i think is truly an important
book
in that it serves as a strong example of
a scientist being both
rigorous and open-minded about the
question
of intelligent alien civilizations in
our universe
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as a side note let me say a bit more
about why avi's work is
so exciting to me and i think to a lot
of people
in 2017 a strange interstellar object
now named amuamoa it's fun to say
was detected traveling through our solar
system based on the evidence we have it
has strange characteristics which made
it not like any asteroid or comet
that we've seen before avi was one of
the only world-class scientists who
fearlessly suggested
that we should be open-minded about
whether it is naturally made
or in fact is an artifact of an
intelligent alien civilization
in fact he suggested that the more
likely explanation
given the evidence is the latter
hypothesis but we also talk about
a lot of fascinating mysteries in our
universe including black holes
dark matter the big bang and close the
speed
of light space travel the theme
throughout is that
in scientific pursuits the weird things
the anomalies
the ideas that right now are considered
taboo should not be ignored
if we're to have a chance at finding the
next big breakthrough
the next big paradigm shift and also
if we are to inspire the world with the
power and beauty of science
if you enjoy this thing subscribe on
youtube review on apple podcast
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connect with me on twitter
and lex friedman and now here's my
conversation
with avi loeb in the introduction to
your new book
extraterrestrial you write this book
confronts one of the universe's most
profound
questions are we alone
over time this question has been framed
in different ways
is life here on earth the only life in
the universe are humans the only
sentient intelligence in the vastness of
space and time
a better more precise framing of this
question would be this
throughout the expanse of space and over
the lifetime of the universe
are there now or have ever been other
sentient civilizations
that like ours explored the stars
and left evidence of their efforts so
let me ask
are we alone that's an excellent
question uh for me
the answer is sort of clear because
i start from the principle of modesty
you know if we believe that we are alone
and special and unique
that shows organs my daughters when they
were infants they tended to think that
they are special
unique and then they went out to the
street
and realized that other kids are very
much like them and
and then they developed a sense of a
better perspective about
themselves and i think the only reason
that we are still thinking that we are
special
is because we haven't searched well
enough to find others
that might even be better than us and
you know i say that because i look at
the newspaper every morning and i see
that we
do foolish things we are not necessarily
the most intelligent ones
and if you think about it if you open a
recipe book
you see that out of the same ingredients
you can make very different cakes
depending on how you put them together
and how you heat them up
and what is the chance that by taking
the
soup of chemicals that existed on earth
and cooking it one way to get
our life that you got the best cake
possible
i mean we are probably not the sharpest
cookie in the jar
and the my question is i mean it's
pretty obvious to me that we're probably
not alone because
half of all the sun-like stars we know
now as astronomers half of the sunlight
stars
from the kepler satellite data have a
planet
the size of the earth roughly at the
same distance that the earth is
from the sun and that means that they
can have liquid water on their surface
and the chemistry of life as we know it
so if you roll the dice
billions of times just within the milky
way galaxy
and then you have tens of billions of
galaxies like it
within the observable volume of the
universe it would be extremely arrogant
to think that we're special i would
think that we're
sort of middle of the road typical forms
of life and that's why
nobody pays attention to us you know if
you go down the street on a sidewalk
and you see an ant you don't pay
attention or a special respect to that
ant you just continue to walk and
so i think that we are sort of average
not very interesting not exciting so
nobody cares about us
we tend to think that we're special but
that's a sign of immaturity and we're
very early on in our development
yes that's another thing that we have
our technology only for 100 years
and it's evolving exponentially right
now on a three-year time scale
so imagine what would happen in a
hundred years in a thousand years
in a million years or in a billion years
now the sun
is actually relatively late in the star
formation
history of the universe most of the
sun-like stars formed earlier
and some of them already died you know
became white dwarfs
and so if you imagine that
a civilization like ours existed around
a typical sun-like star
by now if they survived they could be a
billion years old
and then imagine a billionaire
technology it would look like magic to
us it
you know an approximation to god we
wouldn't be able to understand it
uh and so to in my view we should be
humble
and by the way we should probably just
listen and not speak
because there is a risk right if if
if you are inferior there is a risk if
you speak too loudly
uh something bad may happen to you you
mentioned uh
we should be humble also in the sense
with the analogy to ants
that uh they might be better than us
so there's a kind of scale that we're
talking about and in the
in the question you mentioned the word
sentient
so sentience or maybe the more basic
formulation of that is consciousness do
you think
um do you think that this thing within
us humans in terms of the
typical life form of consciousness
is the essential element that permeates
other if if there's other alien
civilizations out there that they have
something like consciousness as well
or is this i guess i'm asking can you
try to untangle the word sentient
yeah so that's that's a good question uh
i think what is most abundant depending
on how long it survives
so if you look at us as an example
we are now we do have conscious and we
do have technology
but the technologies that we are
developing are also
means for our own destruction yes we can
tell
you know we can change the climate if we
are not careful enough
we can go into nuclear wars so we are
developing
means for our own destruction through
self-inflicted wounds
and it might well be that creatures like
us
are not long-lived that the crocodiles
on other planets live for billions of
years
they don't destroy themselves they live
naturally and so if you look around
the most common thing would be dumb
animals that live for long times you
know not those that have conscious
but in terms of changing the environment
i think since i mean humans develop
tools they've developed the ability
to construct technologies that would
lift us from this planet that we were
born in and that's something
animals without a conscious
consciousness cannot really
do and and so i you know in terms of
uh looking for things that are new that
that went beyond the circumstances they
were born into
i would think that even if they are
short-lived these are
the creatures that made the biggest
difference to their environment
and we can search for them you know even
if they're short-lived
and most of the civilizations are dead
by now yeah
even if that's the case that's sad to
think about by the way well but if you
look on earth
that you know there's lots of cultures
that exist throughout time and they're
dead by now
the mayan culture was very sophisticated
died
but we can find evidence for it and
learn about it just by
archaeology digging into the ground
looking and so we can do the same thing
in space
look for dead civilizations and perhaps
we can learn a lesson
why they died and behave better so that
we will not share the same fate
so i think you know there is a lesson to
be learned from the sky
and by the way i should also say if we
find a technology that we have not
dreamed of that we can import to earth
that may be a better strategy for making
a fortune
than going to silicon valley or going to
wall street
because you learn you make a jump start
into something of the future so that's
one way to do the leap is actually to
find
to literally discover versus come up
with the idea
in our own limited human capacity like a
cognitive capacity it would look like it
would feel like cheating in an exam
where you look over the shoulder of a
student next to you
yeah but it's not good on an exam but it
is good
when you're coming up with technology
that could change the the fabric of
human civilization
but there is uh you know in my
neck of the woods of artificial
intelligence there's a lot of
trajectories one can imagine
of creating very powerful
beings uh the technology that's
essentially
you know you can call super intelligence
that could achieve
space exploration all those kinds of
things without consciousness
right without something that to us
humans looks like consciousness
and there you know there is a sad
feeling i have that consciousness too in
terms of us being humble
is a thing we humans take too seriously
that it's we think it's special just
because we have it but it could be a
thing that's actually holding us back in
some kind of way may well be
it will be uh i should say something
about ai
because i do think it offers a very
important
step into the future if you look at the
old testament the bible
there is this story about noah's ark
that you might
know about noah knew about
a great flood that is about to endanger
all life on earth so he decided to build
an ark
and the bible actually talks about
specifically what the the size of this
ark was what the dimensions were
turns out it was quite similar to um
that we will discuss in a few minutes
but at any event he built this ark
and he put animals on it so that they
were saved from the
great flood now you can think about
doing the same on earth
because there are risks for future
catastrophes you know we could have the
self-inflicted wounds that we were
talking about
like nuclear war changing the climate or
there could be
an asteroid impacting us just like the
dinosaurs died you know they
the dinosaurs didn't have science
astronomy they couldn't
have a warning system but there was this
big stone big rock that approached there
it must have been a beautiful sight yeah
just when it was approaching got very
big and then smashed them
okay and killed them so um you could
have a catastrophe like that
or in a billion years the sun will
basically boil off all the oceans
on earth and
currently all our eggs are in one basket
but we can spread them
it's sort of like the printing press if
you think about it
the revolution that gutenberg brought is
there were
very few copies of the bible at the time
and each of them was precious because it
was handwritten
but once the printing press produced
multiple copies
you know if something bad happened to
one of the copies it wasn't
a catastrophe you know it wasn't
disaster because you had many more
copies that
and so if we have copies of life
here on earth elsewhere then we avoid
the risk of it
being eliminated by a single point
breakdown catastrophe so the question is
can we build
nox spaceship that will carry life as we
know
now you might think we have to put
elephants and
whales and birds on a big spaceship but
that's not true
because all you need to know is the dna
making
the genetic making of these animals put
it on
a computer system that has ai
plus a 3d printer
so that this cubesat which is rather
small
can go with this information to another
planet and use the raw materials there
to produce synthetic life and that would
be a way of producing copies just like
the gutenberg
printing press yeah and it doesn't have
to be exact copies of the humans it
could just
contain some basic elements of life and
then
have enough life on board that it could
uh
reproduce the process of evolution on
another place
right so i mean that also makes you sad
of course because it
uh you confront the mortality of your
own little precious consciousness and
all your own memories and knowledge and
all that stuff right
but who cares i mean we don't know i
care about mine right and you care about
yours
no no i actually don't you know if you
look at the big if you're an astronomer
one thing that you learn from the
universe
is to be modest because you are not so
significant
i mean think about it all these emperors
and kings that conquered a piece of land
on
earth and were extremely proud you know
you see these images
of kings and emperors that you know
usually are alpha males
and they stand you know strong and
um they're very proud of themselves but
if you think about it
there are 10 to the power 20 planets
like the earth
in the observable volume of the universe
and
this view of conquering a piece of land
and even conquering all of earth
is just like an ant hugging a single
grain of sand
on the landscape of a huge beach that's
not very impressive
so you can't be arrogant if you see the
big picture
you have to be humble you know also we
we are short-lived you know we
within a hundred years that's it right
so what does it teach you first to be
humble modest
you never have significant powers
relative to the big scheme of things
and second you should appreciate every
day that you live
yes and and learn about the world humble
and still grateful yes exactly
well let's uh talk about the
probably the most interesting object
i've heard about
and also the most fun to pronounce
can you tell me the story of this object
and why it may be
an important event in human history and
is it possibly a piece of alien
technology
right so this is the first object that
was spotted
close to earth from outside the solar
system
and it was found in on october 19
2017 and at that time it was receding
away from us
and at first astronomers thought it must
be a piece of rock you know just like
all the asteroids and comets that we
have seen from within the solar system
and it just came from another star i
should say that the actual discovery of
this object was surprising to me because
a decade earlier
i wrote the first paper together with ed
turner and
mauro martin that tried to predict
whether the same telescope that was
serving the sky
pan stars from hawaii would find
anything from
interstellar space given what we know
about the solar system so if you assume
that other
planetary systems have similar abundance
of
rocks and you just calculate how many
should be ejected into interstellar
space
the conclusion is no it we shouldn't
find anything
with pan stars to me i apologize it's
probably revealing my
stupidity but it was surprising to me
that so few interstellar objects
from outside this whole system have ever
been detected or
not none has been you you do well
maybe talk about it that there has been
uh uh
one or two rocks since then well since
then there was one
uh called the borisov it was discovered
by
an amateur russian astronomer yeah uh
gennady borisov
and that one looked like a comet
yeah and just like a comet from within
the solar system but this is a really
important point
sorry to interrupt it you showed that
it's unlikely that a rock from another
solar system
would arrive to ours right and so the
actual detection of this one was
surprising by itself
to me yes and
but then so at first they thought maybe
it's a comet or an asteroid but then it
look it didn't look like anything we've
seen before
borisov did look like a comet so people
asked me afterwards and said
you know doesn't it convince you if
borisov
looks like a comet doesn't he convince
you that um is also natural
yeah and i said you know when i went on
the first date with my wife
uh she looked special to me yes and
since then i met many women
yes that didn't change my opinion of my
life so you know that's not an argument
anyway so why did why did the
muah look weird let me explain so first
of all
astronomers monitored the amount of
light sunlight that it reflects
and it was tumbling spinning every eight
hours
and as it was spinning the brightness
that we saw from that direction we
couldn't resolve it because it's tiny
it's
about 100 meters a few hundred feet size
of a football field
and we cannot from earth with existing
telescopes
we cannot resolve it the only way to
actually get a photograph of it
is to send the camera close to it
and that was not possible at the time
that umua was discovered because it was
already moving away from us faster than
any rocket we can send
it's sort of like a guest that appeared
for dinner
and then by the time we realized that
it's weird the guest is already out the
front door into the dark street
yeah what we would like to find is an
object like
it approaching us because then you can
send the camera irrespective of how fast
it moves
and if we were to find it in july 2017
that would have been possible because it
was approaching us at that time
actually i was visiting mount haleakala
in maui hawaii with my family for
vacation at that time in july 2017 but
nobody knew uh
at the observatory that the um
is very close that's sad to think about
that we had the opportunity at that time
yes to send up a camera but don't worry
i mean there will be more there will be
more because
you know i i operate by the copernican
principle which says we don't live at a
special place
and we don't live at a special time and
that means
you know if we surveyed the sky for a
few years
and we had sensitivity to this region
between us and the sun
and we found this object with pan stars
you know there should be many more that
we will find in the future
with surveys that might be even better
yes uh and actually in a
in three years time scale there would be
uh the so-called lsst that's a survey of
the vera rubin observatory
that would be much more sensitive and
could potentially find
an umumua-like object every month
okay so wow i'm just waiting for that
and the main reason for me to alert
everyone uh to the unusual properties of
umumua
is with the hope that next time around
when we see something
as unusual we would take a photograph or
we would get as much evidence as
possible
because science is based on evidence not
on prejudice
and we will get back to that theme so
anyway let me let me point out some of
the properties actually yeah
the elongated nature all right other
things so
the light curve the amount of light
sunlight that was reflected from it
was changing over eight hours by a
factor of ten
meaning that the area of this object
even though we can't resolve it
the area on the sky that reflects
sunlight
was bigger by a factor of 10
in some phases as it was tumbling around
than in other phases so
even if you take a piece of paper that
is razor thin
you know it's there is a very small
likelihood that it's exactly edge-on
uh and getting a factor of 10 change in
the area that you see on the sky
is huge it's much more than any it means
that the object has an unusual geometry
it's at least a factor of a few more
than any of the comets or asteroids that
we have seen before
you mentioned reflectivity so it's not
just the geometry but
the the properties of the surface of
that thing well uh
or no if you assume the reflectivity is
the same okay then it's just geometry if
you assume the reflectivity may change
yes then it could be a combination of
the area that you see and the
reflectivity because
different directions may reflect
differently but the point is that it's
very extreme
yes and it actually the best fit
to the light curve that we saw was of a
flat object
unlike all the cartoons that you have
seen
of a cigar shape a flat object at the 90
percent confidence gives a better model
for the way that the light varied and
it's
like flat meaning like a pancake like a
pancake exactly
uh and then so that's the you know the
very first
unusual property but to me it was not
unusual enough
to think that it might be artificial it
was not
significant enough then um there was no
commentary tale you know
no dust no gas around this object and
the spitzer space telescope
really searched very deeply for
carbon-based molecules
there was nothing so it's definitely not
a comet
the way people expected it to be can you
maybe briefly mention what
uh properties a comet that you're
referring to usually has
right so a comet is a rock that has some
water ice on the surface
so you can think of it as an icy rock
actually comets were discovered a long
time ago but
uh the first model uh
that was developed for them was by fred
the whipple
who was at harvard and i think the
legend goes that he got the idea from
walking through
harvard square and seeing uh during a
winter day
and seeing these icy rocks you know and
so a comet is icy
and this is uh it's just a rock
it's just a wrap yeah so when you have
ice on the surface
when the rock gets close to the sun the
sunlight warms it up
and the the ice sublimates it evaporates
because the one thing about ice water
ice
is it doesn't become liquid if you warm
it up in vacuum
you know without an external pressure
it just goes straight into gas and
that's what you see as the
tail of a comet the only way to get
liquid water
is to have an atmosphere like on earth
that has an external pressure
only then you get liquid and that's why
it's essential to have an
atmosphere to a planet in order to have
liquid water
and the chemistry of life so if you look
at mars
mars lost its atmosphere and therefore
no liquid water on the surface anymore i
mean there may have been early
and that's what the perseverance uh
survey
you know the perseverance mission we
will try to find out whether
it had liquid water whether there was
life perhaps
on it at the time but at some point it
lost its atmosphere
and then the liquid water was gone so
the only reason that we can live
on earth is because of the atmosphere
but a comet is in vacuum
pretty much and then when it gets warmed
up on the surface
the water becomes the water ice becomes
gas and then you see this cometary tail
behind it
in addition to water there is
that there are all kinds of carbon-based
molecules of dust that comes
off the surface and those are detectable
yeah it's easy to detect it's very
prominent you see these cometary tails
that look very prominent because they
reflect sunlight
and you can see them in fact it's
sometimes difficult to see the nucleus
of the comet
because it's surrounded and shrouded
with and in this
case there was no trace of anything
that's fast now
you might say okay it's not a com so
that's what the community said okay it's
not a no problem it's still a rock you
know it's not a comet
but it's just a rock bare rock you know
okay no problem
then and that's the thing that convinced
me to write about it
and then in june 2018 you know
significantly later
there was a report that in fact the
object
exhibited an excess push
in addition to the force of gravity so
the sun acts on it by gravity but then
there was an
extra push on this object that was
figured out from the orbit
that you can trace and the the question
was what is this
excess push so for comets you get the
rocket effect when you evaporate gas
you know just like a jet engine on an
airplane
you throw a jet engine is very simple
you throw the gas back
and it pushes the airplane forward
that's all that's how it get
so in a case of a comet you throw gas in
the direction of the sun because it
and then you get a push okay so in the
case of comets you can get a push
but there was no commentary tale so then
people said oh wait a second
is it an asteroid no but it behaves like
a comet but
it doesn't look like a comet so what it
well forget about it business as usual
so that's what i mean by a
non-gravitational
acceleration so that's interesting so
like the
the primary force acting on something
like just a rock like an asteroid
would be like you can predict the
trajectory based on the
based on gravity and also here there's
detected movement that's
not cannot be accounted purely by the
gravity so if it was a comet
you would need about a tenth of
the mass of this comet the weight of
this government to be evaporated in
order
to give it and there's no sign of that
no sign ten percent of the mass
evaporating it's huge
think about it a hundred meter size
object losing ten percent of its mass
you can't miss that and uh so that's
super weird it's super weird what is
there a good explanation
in your mind and possible explanations
for this you know so i operated just
like sherlock holmes in a way
i said okay what are the possibilities
and the only thing i could think so i
ruled out
everything else and i i said it must be
the sunlight
reflected off it okay so the sunlight
reflects off the surface and gives it a
push
just like you get a push on a sail on a
boat you know from the wind reflecting
off it
now in order for this to be effective it
turns out the object needs to be
extremely thin
uh it turns out it needs to be less than
a millimeter thick
nature does not produce such things so
but
we produce it because it's called the
technology of a light sail
so we are for space exploration we are
exploring this technology because
it it has the benefit of not needing to
carry the fuel
with the spacecraft so you don't have
the fuel you just have a
uh you just have a sail and
it's being pushed either by sunlight or
by a laser beam
or whatever uh so perhaps this is the
light sail so this is
actually the same technology with the
with the starshop project yes
so yeah that's fascinating okay people
afterwards say okay you work on this
project you imagine
you know no that's a pretty good
explanation right obviously my
imagination is limited by what i know
so i you know i would not deny that you
know
working on light sales expanded my
ability to imagine this possibility yes
but let me offer another interesting
anecdote
in september this year 2020 i mean yes
uh
2020. yes um there was
another object found and it was given
the name
2020 so by the
minor planet center you know this is an
organization
actually in cambridge massachusetts that
gives names
to objects astronomical objects found in
the solar system and
they gave it that name 2020 so because
you know it looked like
uh an object in the solar system and
it moved in an orbit that is similar to
the orbit of the earth
but not the same exactly and therefore
it was bound
to the sun but it also exhibited
a deviation from what you expect based
on gravity
so the astronomers that found it
extrapolated back in time and found that
in 1966 it intercepted the earth
and then they realized they went to the
history books and they realized oh there
was a mission
called gruner surveyor lunar lander
surveyor 2 that had a rocket booster it
was a failed mission but
there was a rocket booster that was
kicked into space
and presumably this is the rocket
booster that we are seeing now
this rocket booster was sufficiently
hollow and thin
for us to recognize that it's pushed by
sunlight
so here is my point we can tell from the
orbit of an object obviously this object
didn't have any cometary tail
it was artificially made we know that it
was made by us
and it did deviate from an orbit of a
rock
so just by seeing something that doesn't
have cometary tail
and deviates from an orbit shaped by
gravity
we can tell that it's artificial in the
case of umuamua
it couldn't have been sent by humans
because it just
passed near us for a few months we know
exactly what we were doing in those
at that time and also it was moving
faster than any object that we can
launch
and so obviously it came from outside
the solar system
and the question is who produced it now
i should say that you know when i walk
on vacation on a beach i often see
natural
objects like seashells that are
beautiful and i look at them and
um and every now and then i stumble on a
plastic bottle
and that was artificially produced
and my point is that maybe omua mua was
a message in a bottle
and we should see this is simply another
window
into searching for artifacts from other
civilizations
where do you think it could have come
from and
if it's so okay from a scientific
perspective
the narrow-minded view as we'll probably
talk about throughout is you know you
kind of want to stick to the things that
uh to naturally originating objects like
asteroids and comets
okay that's the space of possible
hypotheses and then if we expand beyond
that
you start to think okay these are
artificially constructed like you just
said it could be by humans
it could be by uh by
whatever that means by some kind of
extraterrestrial alien
civilizations if if it's the alien
civilization
variety what is this object
then that will look at that an excellent
question and
let me lay out i mean we don't have
enough evidence to tell
if we had a photograph perhaps we would
have more information but
the possib there is one other peculiar
fact about umuamua
uh well other than it was very shiny i
that i didn't mention you know we didn't
detect any heat from it and
that implies that it's rather small and
shiny
uh but the other peculiar fact is that
it was it came from a very special frame
of reference
so it's sort of like finding a car in a
parking lot in a public parking lot
that you know you can't really tell
where it came from
so there is this frame of reference
where you average
over the motions of all the stars in the
neighborhood of the sun
so you find the so-called local standard
of rest
of the galaxy and that's uh
a frame of reference that is obtained by
averaging the random
motions of all the stars and the sun is
moving relative to that frame at some
speed
but this object was at rest in that
frame and only one in 500 stars
is so much at rest in that frame and
that's why i was saying it's like a
parking lot
it was parked there and we bumped into
it so the relative speed between the
solar system
and this object is just because we are
moving
it was sitting still now you ask
yourself why is it so
unusual in that context you know why
because if it was
expelled from another planetary system
most likely
it will carry the speed of the host star
that it came from because it was you
know the most loosely bound objects are
in the periphery
of the planetary system and they move
very slowly relative to the star and so
they carry
the when they are ripped apart from the
planetary system most of the objects
will have
the residual motion of the star roughly
relative to the local stuff
but this one was at rest in the locals
now one thing i can think of
if if there is a grid of uh
road posts you know like for navigation
system
so that you can find your way in the
local frame yeah
then that would be one position these
are like little sensors
of that's fascinating to think about so
there could be i mean not necessarily
literally a grid but just uh evenly
in some definition of evenly spread out
set of objects like these
right that are just out there a lot of
them another possibility is that
these are relay stations you know that
for communication
you might think in order to communicate
you need a huge beacon
yeah a very powerful beacon but it's not
true because even on earth you know we
have these relay stations so you have
a not so powerful beacon so it can be
heard only out to a limited distance but
then
you relay the message yes and it could
be one of those
now after it collided with this the
solar system of course it got a kick so
it's just like a
billiard ball you know we gave it a a
kick by colliding with
but most of them are not colliding with
stars and so that's one possibility
okay and there should be numer lots of
them if that's the case
um the other possibility
is that it's a probe you know that was
sent
uh in the direction of the um
habitable region around the sun to find
out if there is life
now it takes tens of thousands of years
for such a probe to traverse the solar
system from the outer edge of the oort
cloud
all the way to where we are and you know
it's a long journey so when it started
the journey from the edge of the solar
system to get to us now
you know we were rather primitive back
then you know we
we still didn't have any technology
there was no reason to visit you know
there was grass around and so forth
but you know maybe it is a problem uh
so you said ten thousand years as fast
so it takes that long tens of thousands
yes tens of thousands a year yeah yeah
and
uh the other thing i should say is you
know it could be just
a a an outer layer of something else
like
you know something that was ripped apart
like a surface of
an instrument that was and and you can
have lots of these pieces you know if
something breaks
lots of these pieces spread out like
space junk and
you know that it could be just space
junk
from an extra from an alien civilization
yes so it's i'm going to tell you about
space junk
let me yes what do you mean by space
junk so
um i think you know you might ask why
aren't they
looking for us one possibility is that
we are not interesting like we were
talking about
another possibility you know if there
are
millions of or billions of years uh
into their technological development
they created their own
their own habitat their own cocoon
where they feel comfortable they have
everything they need
and it it's risky for them to establish
communication with
other so they have their own cocoon and
they close off
they don't care about anything else now
in that case you might say oh
so how can we find about them if they
are closed off
the answer is they still have to deposit
trash
right that's that is something from the
law of thermodynamics
there must be some production of trash
and
you know we can still find about them
just like investigative journalists
going through the trash cans of
celebrities in hollywood you know
you can learn about the private lives of
those celebrities
by looking at the front it's fascinating
to think you know if
if we are the ants in this picture if we
if this thing is a water bottle
or if it's like a smartphone like where
where on the spectrum of possible
objects
of space because there's a lot of
interesting trash
like how interesting is this trash but
imagine a caveman
seeing a cellphone the caveman would
think since the caveman
played with rocks all of his life he
would say it's a rock
just like my fellow astronomers said yes
right exactly
that's brilliantly put actually as a
scientist do you hope it's a water
bottle or a smartphone because a smart
i hope it's even more than a smartphone
i hope that it's something that is
really sophisticated and funny
yeah see i'm the opposite i i feel like
i hope it's a water bottle
because at least we have a hope with our
current
set of skills to understand it yeah
caveman has no way of understanding the
smartphone it's like it will be
like i feel like a caveman has more to
learn from the plastic water bottle than
they do from the smartphone but suppose
we figure it out
if we if we for example come close to it
and and learn
what it's made of and i guess the
smartphone is full of like thousands of
different technologies that we could
probably pick at do you have a sense of
where
a hypothesis of where
is the cocoon that it might have come
from
no because uh okay so first of
all you know the solar system the
outermost edge of the solar system is
called the oort cloud
it's a cloud of icy rocks
um of different sizes
that were left over from the formation
of the solar system
yes and it it's thought to be roughly
a ball or a sphere and it's halfway the
extent of it is roughly halfway to the
nearest
star okay so you can imagine
each planetary system basically
touching uh the oort clouds of those
stars that are near us are touching each
other
space is full of these
billiard balls that are very densely
packed
yes and what that means is any object
that you see
irrespective whether it came from the
local standard so we said that this
object is special because it came from a
local standard of rest but even if it
didn't
you would never be able to trace where
it came from because
all these old clouds overlap so if you
take
some direction in the sky you will cross
as many stars as you have in that
direction like
there is no way to tell which old cloud
it came from so yes
i i didn't realize how densely packed
everything was uh yeah
from the perspective of the work cloud
and that's really interesting so
yeah it could be it could be nearby it
could be very far away yeah we have no
clue
you said cocoon that and you kind of uh
uh paint uh i think in the book i've
read a lot of your articles too on
scientific american which are brilliant
so i'm kind of mixing things up in my
head a little bit
but there's uh what does that
cocoon look like what is the
civilization that's able to harness
the power of multiple suns for example
um
look like they give when you imagine
possible civilizations that are
a million years more advanced than us
what do you think that actually like
looks like i think it's very different
than we can imagine
uh by the way i should start from the
point that
even biological life you know just
without technology
getting into the game uh could look like
something we have never seen before
take for example the nearest star which
is proxima centauri
it's four and a quarter light years away
so they will know
about the results of the 2016 elections
only next month in february 2021 yes
it's very far away um but
if you think about it um you know this
this
uh star is a is a dwarf star
and it's much cooler than it's uh
twice as cold as the sun okay and it
emits mostly infrared radiation
so if there are any creatures on
the planet close to it that is habitable
which is called proxima b
there is a planet in the habitable zone
in the zone just at the right distance
where
in principle liquid water can be on the
surface if there are any animals there
they have infrared eyes because our eyes
was
designed to be sensitive to where most
of the sunlight
is in the visible range but proxima
centaurium is mostly infrared so
you're not the nearest to see each other
in the nearest star system
these animals would be quite strange
they would have
eyes that are detectors of infrared very
different from ours
moreover this planet proxima b faces the
star
always with the same side so it has a
permanent dayside
and a permanent night side and obviously
the creatures that would
evolve on the permanent dayside which is
much warmer
would be quite different than those on
the permanent night side
between them there would be a permanent
sunset
strip and my daughters said that that's
the best
opportunity for high value real estate
because you will see the sunset
throughout your life right now the sun
never sets
on this on this trip so you know these
worlds are out of
our imagination just even the individual
creatures this
the sensor suite that they're operating
with might be very different very
different so i think when we
see something like that we would be
shocked not to speak about seeing
technology now
so i i don't even dare to imagine you
know
uh and i think you know obviously we can
bury our head
in the sand and say it's never aliens
like many of my colleagues say and it's
a self-fulfilling
prophecy if you if you never look you
will never find if you are not ready to
find
wonderful things you will never discover
them
and the other thing i would like to say
is reality
doesn't care whether you ignore it or
not you can ignore reality but it's
still there
yes so we can all agree based on twitter
that aliens don't exist that um
was a rock we can all agree and you will
get a lot of likes
they will have a big crowd of supporters
and everyone
will be happy and give each other awards
and honors and so forth
but um might still be an alien artifact
who cares what humans agree on yeah
there is a reality out there
and we have to be modest enough
to recognize that we should make our
statements based on
evidence science is not about ourself
it's not about glorifying our image it's
not about getting honors
prizes you know a lot of the scientific
a lot of the academic
activity is geared towards creating your
echo chamber where you have students
postdocs repeating your mantras
so that your voice is heard loudly so
that you can get more honors prizes
recognition
that's not the purpose of science the
purpose is to figure out what nature is
right and in the process of doing that
it's a learning experience
you make mistakes you know einstein made
three mistakes at the end of his career
he argued that in the 1930s he argued
that black holes don't exist
gravitational waves don't exist and
quantum mechanics doesn't have spooky
action at a distance
and all three turned out to be wrong
okay so
the point is that if you work at the
frontier of then you make mistakes it's
inevitable because you can't tell what
is true or not
and avoiding making mistakes in order to
preserve your image
makes you extremely boring okay you will
get a prize but you will be a
boring scientist because you will keep
repeating things we already know
if you want to make progress if you want
to innovate you have to take risks
and you have to look at the evidence
it's a dialogue with nature
you don't know the the truth in advance
you let nature tell you educate you
and then you you realize that what you
thought before
is incorrect and a lot of my colleagues
prefer to be in a state where they have
a monologue you know if you look at
these people that work on string theory
yes
uh they have a monologue they know what
and in fact
their monologue is centered on
anti-deceiter space which we don't live
in now you know it's to me it's just
like the olympics you know
you you define a hundred meters and you
say whoever runs this hundred meters
is the best athlete the fastest you know
and uh
it's completely arbitrary you could have
decided it would be 50 meters or 20
meters
who cares you just measure the ability
of people this way
so you define antidecital space as a
space where you do your mathematical
gymnastics
and then you find who can do it the best
and you give jobs based on that you give
prizes best
but as we said before you know nature
doesn't care about
you know the prizes that you give to
each other
it cares you know it has its own reality
and
we should figure it out and it's not
about us the scientific activity is
about
figuring out nature and sometimes we may
be wrong our image will not
be preserved but it's that's the fun you
know
kids explore the world out of curiosity
and
i always want to maintain my childhood
curiosity and
i don't care about the labels that i
have in fact
having tenure is is exactly the
opportunity to
behave like a child because you can make
mistakes yeah and
i was asked by the harvard gazette you
know the the new
the pravda of harvard uh
what what is the one thing that you
would like
to change about the world yes and i said
i would like my colleagues to behave
more like kids
yeah that's the one thing i would like
them to do because
something bad happens to these kids when
they become tenured professors
they start to worry about their ego yeah
and about themselves
more than about the purpose of science
which is
you know curiosity driven figuring out
from evidence evidence is the key
so when an object shows anomalies like
what's the problem discussing you know
whether it's artificial or not
you know so there was i should tell you
there was a mainstream
paper in nature published saying it must
be natural
that's it it's unusual but it must be
natural
period and then at the same time that
those main some other mainstream
scientists
tried to explain the properties yes and
they came up with interpretations like
it's a dust bunny you know the kind that
you find in a household a collection of
dust particles
pushed by sunlight something we have
never seen before
or it's a hydrogen iceberg it actually
evaporates like a
comet but hydrogen is transparent you
don't see it
and that's why we don't see the
commentary again we have never seen
something like that
in both cases the objects would not
survive
the long journey we discussed it in a
paper that i wrote afterwards
but my point is those that try to
explain the unusual properties
went into great length at discussing
things that we have never seen before
okay so even when you think about a
natural origin
you have to come up with scenarios that
of things that were never seen before
and by the way they look less plausible
to me personally
but my point is if we discuss things
that were never seen before
right why not discuss why not
contemplate
an artificial origin what's the problem
why do people have
this pushback you know i worked on on
dark matter
and we don't know what most of the
matter in the universe is
it's called dark metal it's just an
acronym because we have no clue
we simply don't know so it could be all
kinds of particles and over the years
people suggested weakly interacting
massive particles axions
all kinds of particles and experiments
were made
they cost hundreds of millions of
dollars they put upper limits
constraints that ruled out many of the
possibilities that were proposed
as natural initially the mainstream
community regarded it as a mainstream
activity to search
the nature of the dark matter and they
nobody complained that it's speculative
to consider weakly interacting massive
particles
now i asked you why is it speculative to
consider
extraterrestrial technologies we have
a proof that it exists here on earth yes
we also know
that the conditions of of of earth are
reproduced
in billions of systems throughout the
milky way galaxy
so what's more conservative than to say
if you arrange for similar
conditions you get the same outcome how
can you imagine this to be specula it's
not speculative at all
and nevertheless it's regarded the
periphery and at the same time you have
physicists theoretical physics
working on extra dimensions super
symmetry
uh super string theory the multiverse
maybe we live in a simulation all of
these ideas that have no
grounding in reality some of which
sound to me like you know just like what
someone would say
uh science fiction basically because you
have no way to test it
uh you know through experiments and
experiments really are key it's not just
the nuance
you say okay forget about experiment and
some philosophers try to say
you know if there is a consensus what's
the problem the point is
it's key then that's what galileo it's
key to have feedback from reality
you know you can think that you have a
billion dollars or that you are more
rich than you know uh elon musk
that's fine you can feel very happy
about it
you can talk about it with your friends
and all of you will be happy and
think about what you can do with the
money then you go to an atm machine and
you make an experiment
you check how much money you have in in
your checking account
and if it turns out that you know you
you don't have much you can't
you can't materialize your dreams
okay so you realize you have a reality
check yes and my point is
without experiments giving you a reality
check without the atm machine showing
you whether your ideas are bankrupt or
not
without putting skin in the game and by
skinning the game i mean
don't just talk about theoretical ideas
make them testable
if you don't make them testable they're
worthless
they're just like theology that is not
testable
by the way theology has some tests let
me give you
that's interesting three examples yes um
it turns out that my book already
inspired a phd student at harvard in the
english department
to pursue a phd in that direction and
she invited me to the phd exam a couple
of months ago
and in the exam one of the examiners a
professor
asked her do you know why jordano bruno
was burnt at the stake and she said
no i think it's because he was an
obnoxious guy and
irritated a lot of people yes which is
true
but the professor said no it's because
giordano bruno said that other stars
are just like the sun and they could
have a planet like the earth
around them that could host life
and that was offensive to the church why
was it offensive
because there is the possibility that
this life sinned
okay and if that life sinned on planets
around other stars
it should have been saved by christ and
then you need
multiple copies of christ and that's
unacceptable
how can you have duplicates of christ
right and so they burned the guy
it was about that's okay i'm just like
loading this all in because that's kind
of brilliant
so he he was actually already into it's
not just about the stars it's
anticipating that there could be other
life forms yeah
like why if this star if there's other
stars
why would it be special why would our
star be special
he was making the right argument and he
would just follow that
all along to say like there should be
other earth like
places there should be other life and
then there's different copies of christ
yes so that was offensive so i said i
said to that um
i said to that professor i said great
you know i wanted to introduce some
scientific tone to the discussion
and i said this is great because now you
basically laid the f