yeah we haven’t talked about outer space
yet so you thought it was appropriate
for somebody to talk about outer space
so here we go what’s that that’s
something we didn’t know about 20 years
ago
something we didn’t know about when a
lot of us were born and lived most of
our lives that is a system of four
planets in orbit around a star the star
you can’t see because it’s hiding behind
this circular mask in the middle of the
picture and only little glint of the
Starlight are permitted outside of that
by turbulence in the atmosphere we would
block it all out if we could because
it’s the Starlight that makes it so hard
to take pictures of planets because
stars are a billion times brighter than
planets this system of stars is about
129 light years away very far away by
our standards but very close in this by
the standards of the cosmos nowadays we
have about 10,000 planets that we know
the existence of in the nearby portion
of our galaxy in the nearby portion of
the universe and we are developing and
perfecting ways of looking at these
objects to tell whether they are in the
right place to be warm enough and have
water and carbon on all the things that
we associate with life available for
life we are looking for markers of life
that oh that the planets might already
have our progress is marked by the fact
that we know for sure that these four
planets do not harbor life they don’t
have the right kind of atmospheric
signature and it’s not going to be very
long before we figure out how to find
actual habitable planets
you know ones that we can guarantee have
the conditions for life and maybe even
the development of the techniques to
detect detect biospheres that is places
that already harbour life and
civilizations which will have their own
distinctive signatures that we might be
able to tell from a distance whether or
suppose we knew biospheres and
civilizations suppose we knew their
addresses in the local universe we could
go to our neighbors ring their door
bells and introduce ourselves
if anybody answers that would be well
probably one of the events of the week
but mostly it would be a signal event in
our evolution as a species and one of
the most important things that could
ever happen to us in our history and
it’s fun that I get to be part of this
as an explorer of outer space and an
explorer of stars and planets part of
that is timing I was born at just the
right time for the space race one of my
very earliest memories actually probably
is my earliest memory of all was the
first Sputnik I was not quite three
years old and I remember it only because
everybody was talking about it I can
tell you however every detail of the day
that Apollo 11 landed on the moon I
followed all of that stuff of course I
even have favorite astronauts who were
not named Armstrong Aldrin and Collins I
you know to make a long story short it
was probably inevitable that I would
become an astronomer because that was
the the the next step the
forward-looking step of the exploration
of outer space and since then I’ve spent
a good deal of my career making you know
helping make stuff that makes astronomy
possible or easier putting it on
telescopes on the ground in airplanes on
outter on satellites that go into outer
space it’s been a blast it’s I had lots
of important spin-offs and it’s nothing
compared to what is going to happen next
I never thought I’d live to see pictures
like this but now it’s possible that
within my lifetime well what people
remains there are of my lifetime that we
will be able to find much more in the
way of habitable planets inhabited
planets and maybe even civilizations so
here’s a little bit about this next step
round about the beginning of the space
race there was a conference about what
might be next the conference was a bunch
of people from all kinds of scientific
fields and some non scientific fields
led by an astronomer by the name of
Frank Drake in order to frame the
discussion about what we would have to
do to find nearby civilizations Drake
kind of factored the problem in a bunch
of into a bunch of terms that could be
multiplied together if we knew their
values but at least their values could
be guessed at and be used to estimate
well you know are we talking about you
know rarity are we talking about
billions and billions and billions of
civilizations you know we don’t even
know how many planets there are we don’t
even know if planets are rare this is
1960 that got going because it turns out
that the way he decided to factor the
problem whines up corresponding and
interesting ways to thinks that we can
actually measure about the conditions
under which a civilization could develop
that we can figure out without actually
going around to from planet to planet
counting civilizations these these
factors are first of all the number of
stars per year that form in the Milky
Way galaxy then the number of planetary
systems per star and then the number the
fraction of planetary systems that have
a habitable planet a planet Cooke that
can support life
then the factor comes next up here
abbreviated life the fraction of planets
that can support life that actually
evolved life that’s not as easy as it
sounds but it’s also not as hard as I
used to think it was next is how often
life develops into intelligence the
fraction of life emergences that evolved
into intelligence next the fraction of
intelligences that develop into
civilizations by which we mean
technological civilizations
civilizations that can communicate with
their neighbors explore past their
borders explore past their natural
limits all of that and finally the
lifespan of a civilization how long a
civilization might last in the 1960s all
of these things were required wild
guesses and different people’s wild
guesses led to a huge variety of even
wilder guesses about what you get when
you multiply all these seven things
together the only thing that they
thought they were sure about was how
long a civilization lasts they figured
that once it gets started it will last
until the star dies and now we know it’s
while we’re on the subject of time
though of lifespan there’s an
interesting thing to consider about the
timescales on which these things are
expected to happen in outer space
because it was the pace at which they
happened here our universe started off
in an event that we can still see it’s
not a theory but it’s called the Big
Bang we can see the Big Bang it’s not a
theory within the next few million years
after the formation of the Sun all of
the planets formed and get gradually
cleared the areas out around them during
the next 4.6 million years the next two
things on the list took place life
developed life evolved on the surface of
the earth and eventually life
gave rise to intelligence intelligence
took about three million years counting
us as the first intelligence until we
developed into what by our previous
definition is a technological
civilization we became a technological
civilization in an event that occurred
in 1963 which would take me too long to
describe but suffice it to say that we
acquired the ability to communicate with
our neighboring civilizations in 1963 so
it’s been not quite 60 years since we
became a technological civilization so
by the standards of all these times up
here we have we are not just an infant
civilization we are a newborn
civilization we on the cosmic scale of
things we just became a technological
civilization now back to that list what
do the numbers look like these days we
know we haven’t yet gone around and
counted all the civilizations to find
out where the nearest one is but we can
still measure some of these factors and
the important thing the most important
thing that I want to leave you with
today is that most of these things in
the sixty years have become fact the
three at the top signified by the
observatory dome to the left the stars
per year the planetary systems per star
the habitable planets per planetary
system those these are all measurements
these are all observational facts that
we can tell you numbers and
uncertainties in those numbers
the next thing life is also pretty solid
we know the chemical reactions we know
how long an RNA you need to make before
before it can exhibit catalysis and
self-replication the only thing that’s
that we haven’t done yet is make it a a
laboratory preparation and watch for 700
million years to see if it develops into
RNA world and the reason we haven’t done
that is because we haven’t found a
graduate student yet willing to wait
seven hundred million years to get their
PhD but
we’re we’ve run it in simulation we can
do that a lot faster and that’s the end
the answer we get is well 36% but never
mind the the numbers I’m going to tell
you what the product is at the end the
one that’s still kind of squishy is the
is how often you get intelligence once
you have life that we currently figure
to be about 0.3 percent or so there’s
still a range that can be tolerated in
what we know because what we know is
kind of solid but it’s based upon what
happened on earth the emergences of
intelligence on earth and the our
difficulty in figuring out whether the
intelligent beings on earth besides us
are really using language in a sense and
whether they’re they really invented the
tools that they’re using so that’s the
example intelligence will develop into
technological civilizations if we gave
the Dolphins longer they would probably
do so too we usually keep a factor of 2
down from this because you know there
are cetaceans and there are us we’re
civilized they’re not so there’s that
factor of 2 in there that you might
consider to be an uncertainty and then
there’s the lifespan in years and our
hard-working art director Kelly has
represented this for me as a fork in the
road indicating that there are two
possibilities here one possibility is
the dangers and potential disasters that
have been filling our brains and the
news for the well at least the last 30
40 50 years the the problems that come
about when technology is developed by a
civilization and the civilization hasn’t
learned how to control the technology
yet you know all of these things bio
weapon destruction nuclear destruction
catastrophic climate change catastrophic
acidosis of the oceans overpopulation
and resource exhaustion all of those
things
are bad for civilizations they are the
source of a small range of lifespan that
we can call infant mortality amongst
civilizations if you use our current
extrapolations of us and how long we
would last if we don’t do something
about these things we will kill
ourselves by some combination of those
things within about a thousand years so
that is the left hand fork the right
hand fork as it has a number of other
factors in it we could get hit by an
asteroid that happens every of several
tens of millions of years we could
undergo a long period of supervolcano
‘sm some of the some episodes of that
have led to mass extinctions and we
don’t really know how to stop with our
current technology a super volcanic
event we figure though that if a
civilization survives infancy that
there’s a decent chance that it will
figure out what it can do about some of
these other things after all we today
have the technology to protect ourselves
from asteroids we don’t put a lot of
money into it we probably should put
some more money into it because there
are small asteroids that could cause a
lot of havoc and if we knew where they
all were we could do something about it
so getting better at those sorts of
things would require a living past
infancy but once we live past infancy
and figure out what to do about them
then nothing could stop us until the Sun
ran out of hydrogen to burn which will
happen in about one and a half billion
years so there’s two really different
answers depending upon what the fork
takes and they differ by a factor of a
million if you take the short range and
use all of the things that we know about
these previous facts multiply them all
together you get a number how many
civilizations are there in the galaxy
the answer is two one of them presumably
is us and the and the other one if it
could be randomly
where in the galaxy is probably most
probably something like about 34,000
light years away so good luck finding it
the next fork though the 1.5 billion
year fork if we use that we get a number
of three million distribute three
million civilizations around the galaxy
sprinkle them uniformly and the typical
distance between them will be about 80
light years now we’re getting a little
bit more reasonable although that still
seems like a long ways we’re so
impressed by our dangers these days from
the disasters we see looming in front of
us that we’re impressed with the
possibility that infant mortality might
be fairly high amongst civilizations so
let’s make a wild guess what if half of
them make it through and half of them
don’t then you just take our two and
divided by 2 and our three million and
divided by two and you get one and a
half million civilizations to sprinkle
around the galaxy if you sprinkle though
that many civilizations around the
galaxy and ask what’s the typical
distance between neighboring ones you
get a hundred light-years by a typical
distance I mean it’s a 50/50 chance
whether that nearest civilization is
closer than a hundred light-years or
further away than a hundred light-years
so that’s a definition of our
neighborhood our neighborhood in terms
of where are our neighboring
civilizations might be is about a
hundred light years so what does that
look like this is what it looks like we
know an awful lot about the stars in the
sky and their positions and how far away
they are we’ve measured the distances to
billions of stars and we know that
within a hundred light-years of the Sun
there are about thirty eight hundred and
twenty three stars and this is all of
them plotted in the form of a sphere if
you’re sitting in the front you might be
able to tell that there’s a whole bunch
of little red dots if you’re sitting in
the back you’ll probably only see the
blue ones we don’t care about them
because they’re not going to support
life but the there there are lots and
lots of these the importance of this is
that there’s a good chance
a really good chance that one of these
dots has our nearest neighboring
civilization so what do we do well
here’s what we’re going to do during the
next 20 or 30 years astronomers are
going to continue to refine and perfect
their techniques for figuring out what
the planets of all these stars are up to
already it’s clear that about a quarter
of these stars have habitable planets
around them that is planets that we
figure have the right conditions to have
liquid water or thin atmosphere carbon
all the things that we like for for life
but we will get good during the next 20
or 30 years at detecting biospheres that
is looking for signatures in the stars
in the planets light that indicates that
life has already taken place it has
already evolved on these on these things
we might even get good at finding a
signature in an atmosphere that in a
planetary atmosphere that it is
characteristic of a civilization going
on there like you know some some
pollutant or other that that they
haven’t figured out how to get rid of
yet that is during the next 20 or 30
years there are going to be some
addresses in this neighborhood that we
introduce ourselves to the neighbors
that’s interesting and it brings up
three points that I would like to close
with first of all that sphere is a
hundred light-years in radius two
hundred light-years in diameter if you
travel at the speed of light that means
it takes you a hundred years to get from
the center to the outskirts and your
spaceship doesn’t go the speed of light
your spaceship your fastest spaceship
the fastest spaceship we’ve ever made
goes about a factor of 10,000 slower
than the speed of light we’ve got a long
way to go before we figure out how to
travel through fast so exploring in star
trek fashion by going from star to star
and planet
to planet each leg in the journey will
take many human lights and well that we
get back to the problem of the graduate
students time to degree yeah you know
we’re not going to be able to convince
very many people to do that so that’s
point number one point number two we can
however communicate because
communication that is radio waves which
are a form of light or infrared light or
visible light whatever like you want to
communicate with travels at the speed of
light if we knew the addresses of the
most promising planets we could
broadcast a signal in their direction
and listen for a reply the reply might
take a long time to get for instance if
our nearest civilization is on the edge
of this sphere getting the signal out
there takes a hundred years getting
their reply back takes a hundred years
nobody knows how long they’re going to
take before they figure out what to say
to us so a long time third though that’s
cheap broadcasting is cheap by the
standards of space programs telescopes
that could be used to beam those signals
are cheap it’s something that we can do
you might wonder whether it would be a
good idea to do and that brings me to
the the idea of those the numbers that
we just calculated for the civilizations
if we have 50 percent infant mortality
then there are 1,500 well sorry 1.5
million civilizations that have lived
through it and then there’s us if they
live through it they’re a lot older than
we are if they’re a lot older than we
are they’re a lot more advanced than we
are many people have done that
calculation and came to the conclusion
that since aliens are light so much more
likely to be advanced than we are it
to which I would say look
with our current technology we’re about
to be able to tell who on this on this
plot is a civilization or not they’re
doing it too they know we’re here
and still they haven’t shown up we’ve
happy that you know that that might tell
you all you need to know about the
difficulties of long distance space
travel for for humanoid like organisms
or it might just say that they’ve from a
distance and by whatever means they’ve
considered that we’re not cool enough to
come visit but that that is that is an
issue the issue is that they are very
likely to be very advanced I think
that’s a great reason to ring their
doorbell to communicate with them to
communicate with us with a civilization
that has lived through its infancy and
has figured out how to control the
technology that they have created Wow
I want to talk to them these are the
people we need to talk to these I
suppose I should just call them aliens
these are the aliens we need to talk to
they can help us they can help us get
through if we get a reply back and learn
something about what they found useful
in controlling their technologies and
living through infancy so that they
don’t die of killing the oceans runaway
thermal you know global warming all of
the things that that that make things
dangerous so there you are in 20 or 30
years we’re going to have some addresses
and we’re going to be faced with the
decision of should we introduce
ourselves to the neighbors and I say
let’s ring the doorbell thanks [Applause]
yet so you thought it was appropriate
for somebody to talk about outer space
so here we go what’s that that’s
something we didn’t know about 20 years
ago
something we didn’t know about when a
lot of us were born and lived most of
our lives that is a system of four
planets in orbit around a star the star
you can’t see because it’s hiding behind
this circular mask in the middle of the
picture and only little glint of the
Starlight are permitted outside of that
by turbulence in the atmosphere we would
block it all out if we could because
it’s the Starlight that makes it so hard
to take pictures of planets because
stars are a billion times brighter than
planets this system of stars is about
129 light years away very far away by
our standards but very close in this by
the standards of the cosmos nowadays we
have about 10,000 planets that we know
the existence of in the nearby portion
of our galaxy in the nearby portion of
the universe and we are developing and
perfecting ways of looking at these
objects to tell whether they are in the
right place to be warm enough and have
water and carbon on all the things that
we associate with life available for
life we are looking for markers of life
that oh that the planets might already
have our progress is marked by the fact
that we know for sure that these four
planets do not harbor life they don’t
have the right kind of atmospheric
signature and it’s not going to be very
long before we figure out how to find
actual habitable planets
you know ones that we can guarantee have
the conditions for life and maybe even
the development of the techniques to
detect detect biospheres that is places
that already harbour life and
civilizations which will have their own
distinctive signatures that we might be
able to tell from a distance whether or
suppose we knew biospheres and
civilizations suppose we knew their
addresses in the local universe we could
go to our neighbors ring their door
bells and introduce ourselves
if anybody answers that would be well
probably one of the events of the week
but mostly it would be a signal event in
our evolution as a species and one of
the most important things that could
ever happen to us in our history and
it’s fun that I get to be part of this
as an explorer of outer space and an
explorer of stars and planets part of
that is timing I was born at just the
right time for the space race one of my
very earliest memories actually probably
is my earliest memory of all was the
first Sputnik I was not quite three
years old and I remember it only because
everybody was talking about it I can
tell you however every detail of the day
that Apollo 11 landed on the moon I
followed all of that stuff of course I
even have favorite astronauts who were
not named Armstrong Aldrin and Collins I
you know to make a long story short it
was probably inevitable that I would
become an astronomer because that was
the the the next step the
forward-looking step of the exploration
of outer space and since then I’ve spent
a good deal of my career making you know
helping make stuff that makes astronomy
possible or easier putting it on
telescopes on the ground in airplanes on
outter on satellites that go into outer
space it’s been a blast it’s I had lots
of important spin-offs and it’s nothing
compared to what is going to happen next
I never thought I’d live to see pictures
like this but now it’s possible that
within my lifetime well what people
remains there are of my lifetime that we
will be able to find much more in the
way of habitable planets inhabited
planets and maybe even civilizations so
here’s a little bit about this next step
round about the beginning of the space
race there was a conference about what
might be next the conference was a bunch
of people from all kinds of scientific
fields and some non scientific fields
led by an astronomer by the name of
Frank Drake in order to frame the
discussion about what we would have to
do to find nearby civilizations Drake
kind of factored the problem in a bunch
of into a bunch of terms that could be
multiplied together if we knew their
values but at least their values could
be guessed at and be used to estimate
well you know are we talking about you
know rarity are we talking about
billions and billions and billions of
civilizations you know we don’t even
know how many planets there are we don’t
even know if planets are rare this is
1960 that got going because it turns out
that the way he decided to factor the
problem whines up corresponding and
interesting ways to thinks that we can
actually measure about the conditions
under which a civilization could develop
that we can figure out without actually
going around to from planet to planet
counting civilizations these these
factors are first of all the number of
stars per year that form in the Milky
Way galaxy then the number of planetary
systems per star and then the number the
fraction of planetary systems that have
a habitable planet a planet Cooke that
can support life
then the factor comes next up here
abbreviated life the fraction of planets
that can support life that actually
evolved life that’s not as easy as it
sounds but it’s also not as hard as I
used to think it was next is how often
life develops into intelligence the
fraction of life emergences that evolved
into intelligence next the fraction of
intelligences that develop into
civilizations by which we mean
technological civilizations
civilizations that can communicate with
their neighbors explore past their
borders explore past their natural
limits all of that and finally the
lifespan of a civilization how long a
civilization might last in the 1960s all
of these things were required wild
guesses and different people’s wild
guesses led to a huge variety of even
wilder guesses about what you get when
you multiply all these seven things
together the only thing that they
thought they were sure about was how
long a civilization lasts they figured
that once it gets started it will last
until the star dies and now we know it’s
while we’re on the subject of time
though of lifespan there’s an
interesting thing to consider about the
timescales on which these things are
expected to happen in outer space
because it was the pace at which they
happened here our universe started off
in an event that we can still see it’s
not a theory but it’s called the Big
Bang we can see the Big Bang it’s not a
theory within the next few million years
after the formation of the Sun all of
the planets formed and get gradually
cleared the areas out around them during
the next 4.6 million years the next two
things on the list took place life
developed life evolved on the surface of
the earth and eventually life
gave rise to intelligence intelligence
took about three million years counting
us as the first intelligence until we
developed into what by our previous
definition is a technological
civilization we became a technological
civilization in an event that occurred
in 1963 which would take me too long to
describe but suffice it to say that we
acquired the ability to communicate with
our neighboring civilizations in 1963 so
it’s been not quite 60 years since we
became a technological civilization so
by the standards of all these times up
here we have we are not just an infant
civilization we are a newborn
civilization we on the cosmic scale of
things we just became a technological
civilization now back to that list what
do the numbers look like these days we
know we haven’t yet gone around and
counted all the civilizations to find
out where the nearest one is but we can
still measure some of these factors and
the important thing the most important
thing that I want to leave you with
today is that most of these things in
the sixty years have become fact the
three at the top signified by the
observatory dome to the left the stars
per year the planetary systems per star
the habitable planets per planetary
system those these are all measurements
these are all observational facts that
we can tell you numbers and
uncertainties in those numbers
the next thing life is also pretty solid
we know the chemical reactions we know
how long an RNA you need to make before
before it can exhibit catalysis and
self-replication the only thing that’s
that we haven’t done yet is make it a a
laboratory preparation and watch for 700
million years to see if it develops into
RNA world and the reason we haven’t done
that is because we haven’t found a
graduate student yet willing to wait
seven hundred million years to get their
PhD but
we’re we’ve run it in simulation we can
do that a lot faster and that’s the end
the answer we get is well 36% but never
mind the the numbers I’m going to tell
you what the product is at the end the
one that’s still kind of squishy is the
is how often you get intelligence once
you have life that we currently figure
to be about 0.3 percent or so there’s
still a range that can be tolerated in
what we know because what we know is
kind of solid but it’s based upon what
happened on earth the emergences of
intelligence on earth and the our
difficulty in figuring out whether the
intelligent beings on earth besides us
are really using language in a sense and
whether they’re they really invented the
tools that they’re using so that’s the
example intelligence will develop into
technological civilizations if we gave
the Dolphins longer they would probably
do so too we usually keep a factor of 2
down from this because you know there
are cetaceans and there are us we’re
civilized they’re not so there’s that
factor of 2 in there that you might
consider to be an uncertainty and then
there’s the lifespan in years and our
hard-working art director Kelly has
represented this for me as a fork in the
road indicating that there are two
possibilities here one possibility is
the dangers and potential disasters that
have been filling our brains and the
news for the well at least the last 30
40 50 years the the problems that come
about when technology is developed by a
civilization and the civilization hasn’t
learned how to control the technology
yet you know all of these things bio
weapon destruction nuclear destruction
catastrophic climate change catastrophic
acidosis of the oceans overpopulation
and resource exhaustion all of those
things
are bad for civilizations they are the
source of a small range of lifespan that
we can call infant mortality amongst
civilizations if you use our current
extrapolations of us and how long we
would last if we don’t do something
about these things we will kill
ourselves by some combination of those
things within about a thousand years so
that is the left hand fork the right
hand fork as it has a number of other
factors in it we could get hit by an
asteroid that happens every of several
tens of millions of years we could
undergo a long period of supervolcano
‘sm some of the some episodes of that
have led to mass extinctions and we
don’t really know how to stop with our
current technology a super volcanic
event we figure though that if a
civilization survives infancy that
there’s a decent chance that it will
figure out what it can do about some of
these other things after all we today
have the technology to protect ourselves
from asteroids we don’t put a lot of
money into it we probably should put
some more money into it because there
are small asteroids that could cause a
lot of havoc and if we knew where they
all were we could do something about it
so getting better at those sorts of
things would require a living past
infancy but once we live past infancy
and figure out what to do about them
then nothing could stop us until the Sun
ran out of hydrogen to burn which will
happen in about one and a half billion
years so there’s two really different
answers depending upon what the fork
takes and they differ by a factor of a
million if you take the short range and
use all of the things that we know about
these previous facts multiply them all
together you get a number how many
civilizations are there in the galaxy
the answer is two one of them presumably
is us and the and the other one if it
could be randomly
where in the galaxy is probably most
probably something like about 34,000
light years away so good luck finding it
the next fork though the 1.5 billion
year fork if we use that we get a number
of three million distribute three
million civilizations around the galaxy
sprinkle them uniformly and the typical
distance between them will be about 80
light years now we’re getting a little
bit more reasonable although that still
seems like a long ways we’re so
impressed by our dangers these days from
the disasters we see looming in front of
us that we’re impressed with the
possibility that infant mortality might
be fairly high amongst civilizations so
let’s make a wild guess what if half of
them make it through and half of them
don’t then you just take our two and
divided by 2 and our three million and
divided by two and you get one and a
half million civilizations to sprinkle
around the galaxy if you sprinkle though
that many civilizations around the
galaxy and ask what’s the typical
distance between neighboring ones you
get a hundred light-years by a typical
distance I mean it’s a 50/50 chance
whether that nearest civilization is
closer than a hundred light-years or
further away than a hundred light-years
so that’s a definition of our
neighborhood our neighborhood in terms
of where are our neighboring
civilizations might be is about a
hundred light years so what does that
look like this is what it looks like we
know an awful lot about the stars in the
sky and their positions and how far away
they are we’ve measured the distances to
billions of stars and we know that
within a hundred light-years of the Sun
there are about thirty eight hundred and
twenty three stars and this is all of
them plotted in the form of a sphere if
you’re sitting in the front you might be
able to tell that there’s a whole bunch
of little red dots if you’re sitting in
the back you’ll probably only see the
blue ones we don’t care about them
because they’re not going to support
life but the there there are lots and
lots of these the importance of this is
that there’s a good chance
a really good chance that one of these
dots has our nearest neighboring
civilization so what do we do well
here’s what we’re going to do during the
next 20 or 30 years astronomers are
going to continue to refine and perfect
their techniques for figuring out what
the planets of all these stars are up to
already it’s clear that about a quarter
of these stars have habitable planets
around them that is planets that we
figure have the right conditions to have
liquid water or thin atmosphere carbon
all the things that we like for for life
but we will get good during the next 20
or 30 years at detecting biospheres that
is looking for signatures in the stars
in the planets light that indicates that
life has already taken place it has
already evolved on these on these things
we might even get good at finding a
signature in an atmosphere that in a
planetary atmosphere that it is
characteristic of a civilization going
on there like you know some some
pollutant or other that that they
haven’t figured out how to get rid of
yet that is during the next 20 or 30
years there are going to be some
addresses in this neighborhood that we
introduce ourselves to the neighbors
that’s interesting and it brings up
three points that I would like to close
with first of all that sphere is a
hundred light-years in radius two
hundred light-years in diameter if you
travel at the speed of light that means
it takes you a hundred years to get from
the center to the outskirts and your
spaceship doesn’t go the speed of light
your spaceship your fastest spaceship
the fastest spaceship we’ve ever made
goes about a factor of 10,000 slower
than the speed of light we’ve got a long
way to go before we figure out how to
travel through fast so exploring in star
trek fashion by going from star to star
and planet
to planet each leg in the journey will
take many human lights and well that we
get back to the problem of the graduate
students time to degree yeah you know
we’re not going to be able to convince
very many people to do that so that’s
point number one point number two we can
however communicate because
communication that is radio waves which
are a form of light or infrared light or
visible light whatever like you want to
communicate with travels at the speed of
light if we knew the addresses of the
most promising planets we could
broadcast a signal in their direction
and listen for a reply the reply might
take a long time to get for instance if
our nearest civilization is on the edge
of this sphere getting the signal out
there takes a hundred years getting
their reply back takes a hundred years
nobody knows how long they’re going to
take before they figure out what to say
to us so a long time third though that’s
cheap broadcasting is cheap by the
standards of space programs telescopes
that could be used to beam those signals
are cheap it’s something that we can do
you might wonder whether it would be a
good idea to do and that brings me to
the the idea of those the numbers that
we just calculated for the civilizations
if we have 50 percent infant mortality
then there are 1,500 well sorry 1.5
million civilizations that have lived
through it and then there’s us if they
live through it they’re a lot older than
we are if they’re a lot older than we
are they’re a lot more advanced than we
are many people have done that
calculation and came to the conclusion
that since aliens are light so much more
likely to be advanced than we are it
to which I would say look
with our current technology we’re about
to be able to tell who on this on this
plot is a civilization or not they’re
doing it too they know we’re here
and still they haven’t shown up we’ve
happy that you know that that might tell
you all you need to know about the
difficulties of long distance space
travel for for humanoid like organisms
or it might just say that they’ve from a
distance and by whatever means they’ve
considered that we’re not cool enough to
come visit but that that is that is an
issue the issue is that they are very
likely to be very advanced I think
that’s a great reason to ring their
doorbell to communicate with them to
communicate with us with a civilization
that has lived through its infancy and
has figured out how to control the
technology that they have created Wow
I want to talk to them these are the
people we need to talk to these I
suppose I should just call them aliens
these are the aliens we need to talk to
they can help us they can help us get
through if we get a reply back and learn
something about what they found useful
in controlling their technologies and
living through infancy so that they
don’t die of killing the oceans runaway
thermal you know global warming all of
the things that that that make things
dangerous so there you are in 20 or 30
years we’re going to have some addresses
and we’re going to be faced with the
decision of should we introduce
ourselves to the neighbors and I say
let’s ring the doorbell thanks [Applause]
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