March 19, 2013 • 16 mins
Is there life out there in the cosmos and if so how do we find it? How might it find us? In this episode of Stuff to Blow Your Mind, Julie and Robert discuss the history of SETI as well as what classic TV shows our alien neighbors might be listening to.
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Speaker 1 (00:03):
Welcome to stuff to Blow your mind from how Stuff
Works dot com. Hey you welcome to Stuff of all
your mind. My name is Robert Lamb and I'm Julie Douglas.
And you know, when you look at space explorestion, you
know we're looking outward, but then there's also a lot
of looking inward. Um. It's just about anything humans do.
(00:25):
You can sort of make a case for the selfishness
of it and the self absorption of it. So we
look out into space because we want to know something
about ourselves. A lot of the times we want to
know what's out there because we want to know where
we fit in. We want to know if there's intelligent
life or life out there at all, because that puts
who we are and what we are in some level
of perspective. And that's one area where set comes into play,
(00:48):
the search for extraterrestrial intelligence. Right, So, as long as
there have been humans, um, there has been this question
of are we alone in the universe? Because you can't
help but look up in the night sky and say,
is that it? You know? Is there? Are we unique?
There are all sorts of questions that roll out here. Now.
Of course, astrophysicists astrobiologists, um, astronomers are all trying to
(01:11):
answer this question, and they're looking more though, in the
infancy infancy of really this possibility of intelligent life. And
when I say infancy, I'm talking more about Mars and
the possibility of microbial life there, or Jupiter's moon Europa
and the presence of water underneath the frozen oceans, or
liquid hydrocarbon lakes on Saturdays moon Titan. So we have
(01:36):
to look there first because we know that those are
sort of the building blocks of microbial life, which then
evolves into something more significant or complex, I should say. So,
of course this leads to this question of well, are
we really unique? Um? Is life the flora and fauna
on Earth unique to us? Is that it? Um? And
(01:56):
this is a huge question and we have to unpack
it a little bit. Yeah. I mean, as we've discussed before,
when when you're talking about life, I mean, ultimately we
have the one model to go on. So we inevitably
we keep coming back to that, what is life and
so stuff on this planet? What are the parameters for
life as we have seen it so far as we
know it? And uh, and what are what's the chemical
(02:19):
formula for what is required, what elements? When do we
need to look for? It's uh, I often think about it.
It's kind of like um, shopping for a new house.
You know, you're looking at all right now, what what's
what kind of neighborhood do I want to live in? What? What?
What do I need to be close enough to? What
resources need to be nearby to make it agreeable? What?
What type of neighborhood is is too hostile to me? Uh?
(02:40):
You know, like one one area is going to be
too fancy, too too rich, just excluding completely another area, uh,
might be a war zone. You know. We have to
say to take all of this into into account even
when we're looking for extratrustrial life, because we're looking at
where where else could life exist more or less like
it exists here, You're right, So we really have to
(03:01):
turn to ourselves. And we know that the chemical composition
of earth face life consists of hydrogen, carbon, and oxygen.
So that accounts for more than of the atoms and
the human body and in all other known life. So
of those three, carbon is really the star of the show,
since it can bond with itself and other molecules really easily,
and it's a very strong bond. Now, if you kind
(03:24):
of take the lens here from from humans and um
and another life on Earth, and you sort of go
out a little bit into the universe, what do you find?
You find the most common elements in the universe are hydrogen, helium, carbon,
and oxygen. Okay, So what is this saying. This is
saying that, uh, life is not chemically special, especially if
(03:48):
you consider that the basis of it can be easily
found in the universe and then harnessed here on Earth.
And if life on Earth were composed primarily of manganese
or molly bendum, then we would have excellent reason to
suspect that we're something special in the universe. But it's not. Yeah,
all this stuff is everywhere. It's kind of you know,
(04:08):
it's kind of like you know when you you're a
certain age and you find this book that you really
dig and you're like, oh, my goodness, is it the
most n album? Say it's an album by a group,
and you're like, how this is the most precious thing? This?
I love this, this album in this book so much.
It speaks directly to me. The artist is speaking directly
to me, and only I can really appreciate it in
the way that I'm appreciating it now. And then you realize, oh,
it's a nation nationwide bestseller, or it's it's on the
(04:31):
top ten Billboard charts, or you know, the went triple
platinum or whatever, and you realize, oh, actually, this appeals
to a lot of people, and I am not special
in liking it. Yeah, and you discover that it's playing
throughout the universe, right, the same music, and it's the
same elements, those same ingredients that make us that are
out there in the stars. But we've talked about this before,
because you've talked about if his start implodes um, you know,
(04:52):
it's throwing out all sorts of material into the universe.
And you know, there's that the great quote by Lawrence
Cross says, you know the atoms in your right hand
are in your left hand all came from that one
star exploding. So it makes sense. This is this is
the stuff that's making that soup. This is the base
of the soup. Um. And if you take that logic,
(05:14):
then you start to say, Okay, it's not unique. This
is a recipe that could be executed elsewhere on the universe. Yes,
But of course the thing about recipes. Um, so we
all know is that it's it's not merely enough to
know what goes in, but you have to know, uh
what amounts going You need to know is it is
it a tablespoon of salt or a teaspoon of salt?
(05:34):
Um makes the world of difference. Um, are certain substitutions allowed,
which ones are not? How are you heating it? How
are you preparing it to make all the difference in
in the ultimate outcome of the recipe? And likewise there
is a lot of that to take into account, just
chemically with with Earth and life on Earth. In his
book The Autographs, Diyson points out the oxygen thing. You
need a lot of free oxygen and that needs to
(05:57):
be supported by some sort of a system on our
planet's ported of course, by all the vegetation that we
we have on this planet. So you have to have
the right circumstances in place to allow the right chemical
situation to be in order. So evolution is kind of
like the baking time, right. So if it takes ten
billion years for a planet become hospitable, then that's ten
(06:18):
billion years of baking time. And so you have to
consider that when when we're talking about exo planets, and
we're talking about them being just the right distance from
the star or um from a sent or a moon
to have the correct elements there for the baking. Right,
that's just one aspect of it. But again, the ingredients
for the recipe your out there, which makes it so
(06:40):
tantalizing of a question of whether or not there exists
other life and intelligent life at that UM. Of course,
we had to go back to something called the Copernican principle,
uh to really sort of understand how life may not
be that special in the first place. Yeah. And then this,
of course kind from should say chemical life. Yes, this
(07:02):
of course comes to us from a mid Polish astronomer,
Nicolas Copernicus. Um and uh. And basically the whole deal
here is that we're nothing special, and that you cannot
enter a scientific analysis of the universe with the idea
that we're something special. There are a number of different
(07:23):
things that spin off of this, For instance, UM. In
nineteen seventy four, astronomer Brandon Carter tackled the quandary of
our anti anthropic coincidence, the idea that there are a
number of coincidences that supposedly make life on Earth possible UM,
and he hypothesized that these coincidence are part of the
universe very structure, and the chance has nothing to do
with it. He proposed two variants, the most important what
(07:46):
we're talking about here is the strong anthropic principle UH.
And in this he drew on the Copernican principle UH,
which again states that there's nothing special or privileged about
Earth or humanity. Uh. We live in a universe capable
of supporting life than than only life supporting universes are possible.
You can really go down the rabbit hole with this,
But essentially it's about putting aside any idea that we
(08:09):
are special. Again, the the the album is a hit
around the universe that the building blocks are out there. Uh.
We can't enter into any kind of an analysis of
or even of a pondering of life else where in
the universe if we're thinking that we're special in some way. Yeah.
And what I really like about the comparonic in principle
(08:29):
is that it does show an evolution of understanding of
our place in the universe, because you know, Comparnicas of
sitting there saying at a time where everybody was thinking
the opposite is saying, hey, the Earth is not the
center of our solar system. And so, of course that
was a crazy thought at the time. Yeah, because for
the longest, Yeah, Earth has to be the center. We're
the center God's blessed creation. So we should be right
(08:54):
there at the center. How can this whole thing not
be about us? Right? We are it right? Um. But
then there's this idea that evolves even more like, okay, hey,
well we're not the center of the Solar system in
the Milky Way, by the way, our Milky Way, our
galaxy is not the center of universe. In fact, we're
not quite sure what the center is. Is there a center? Um?
So you really do see this, This understanding become much
(09:15):
more complex and nuanced as we get more and more
data from the world around us, because now we understand
that Earth is just one of billions of planets that
are all bathing in the same sort of primary chemicals. Um.
So that gets us to this area called the Drake equation.
So we really have to talk about this before we
(09:36):
can even sort of say, okay, we'll do aliens exist,
How would they exist? How would we contact them? All? Right,
We're gonna take a quick break and when we come
back even more on the search for extraterrestrial intelligence. Yes,
(09:57):
the Drake equation. So the Drake equation is pretty widely known.
It's been spun off into a number of interesting little
side projects, like there was a there's a really good
episode of This American Life where that's a team of
scientists try to use the Drake equation to determine whether
they have a true love match out there in the
world waiting for them, as opposed to is there another
(10:18):
life form or other life forms elsewhere in the galaxy. Yeah,
because I want to say this just at the front here,
that the Drake equation is not something that is solvable.
It is it's really about probabilities and how to organize
our thoughts about the data that we have in the
missing data. Yeah, it's about taking the one big question,
the one big probability is their life else from in
(10:39):
the universe, and breaking it down into smaller questions, smaller
probabilities that we can tackle individually. So the entire equation
looks like this, and and this is not gonna all
make a lot of sense, but just in the in
the in the interest of getting out there, it is
in equals our star multiplied by F sub p multiplied
by in sub multiplied by F sub F sub l
(11:02):
multiplied by F sub i multiplied by F subc multiplied
by capital l. And so all those numbers must by
together help us to estimate the number in of technical
logical civilizations that might be able to detect us right now. Now,
if you guys all bear with me, let me unpack
that a little bit, because I do think it's interesting.
Um our star is the rate at which stars have
(11:23):
been born in the Milky Way galaxy over the last
few billion years. That stars per year, okay, And then
all the f factors in this are fractions. So F
sub p is a fraction of stars that have planets,
and sub e is the average number of habitable planets
in any planetary system. F sub l is the fraction
of planets on which life actually begins. F sub i
(11:45):
is a fraction of all those life forms that develop intelligency.
How this becomes Tinier and jiner um. And then F
sub c is the fraction of intelligent life that develop
a civilization that uses some sort of transmitting technology. Finally, L,
which is really important here, and we'll talk more about
this later l is the longevity factor. On average, how
(12:06):
many years do those transmitters continue to operate, because, as
we know, civilizations come and go. Yeah, Like I kind
of like to think of it in terms of a
video store, like you know, and some of you may ask,
what what what is that? Because they are starting to
disappear more and more. But like in the Atlanta we
have this really cool video store called Video Drome. I
still like to go there just to brows around for
(12:27):
nostalgia and nothing else. But you know, I walk into
a video store and I have, you know, X number
of videos at my disposal for possible rent. But then
you have to you have to carve that down all right,
of all the videos here, I can only check out
ones that are checked in, so that dude decreases the number.
Then maybe I'm only interested in seeing an English language
film because I don't want to read subtitles tonight, So
(12:49):
then we have to cut that down. Then I must
say I'm only interested in seeing a horror movie, so
that cuts it down even more. And then I only
interested in seeing a horror movie that I haven't already seen,
so that cuts it down even more. And again you
just get down to there are x number of films
that I could potentially rent this evening. Now, what I
think is cool about this dract equation is that, yes,
there's no righting answer right now, and this is just
(13:11):
a way of organizing information because a lot of it
does depend on who's plugging in the data and why
right in the same way that my data I plug
into this video drum equation could be different one day
from the next. The deal is, though, is that astronomers
are actually getting at this equation right. They've already tried
to figure out about three of those different fractions, So
they're trying to figure out the fraction of stars planets,
(13:33):
the average number of habitable planets, and the fraction of
planets on which life actually begins. So they're getting to that.
So when I talk about exit planets that are habitable
and that goldilocks not too hot, not too cold, that'
from one aspect of it that they're beginning to collect
data on um and they're beginning to say like, okay, well,
now we can get these chemical signatures and try to
(13:55):
figure out, you know, how much carbon is being produced there,
how much method sane which you know something we'll talk
more about as pretty plentiful here on Earth, and that's
a that's a huge signal if there's something going on
on that planet, right probably probably cows as well as
other you know, factors that that create methane that I
(14:16):
won't go into. Uh, But anyway, my point is is
that yes, this is, uh, this is somewhat of a
thought experiment, but astronomers are scratching away at it and
they're getting some concrete information in there. Yeah. Um, I
mean historically whether the estimate the results have varied again
depending on what's going into it, and they varied from
there being one one but one civilization out there two millions.
(14:38):
So yeah, right, Again, there's a lot of data that
needs to be plugged in here, but astronomers are if
if you will, plugging away at that. Now, I wanted
to mention the Fermi paradox, and this is something I
want you guys to all put in your back pocket
as you consider all the other information that we talked
about today. The Fermi paradox is from the Noble Prize
winning physicist and Rico Fantom and he reasoned that if
(15:02):
it takes life billions of years, should develop intelligence and
signal or travel to the stars. And if there are
billions of worlds in the universe, and if the universe
is over thirteen billion years old, then why haven't we
been visited by an extra terrestrial or why isn't the
galaxy crawling with extraterrestrials. This is something we'll get too later.
(15:25):
But that's that's a good question, right, yeah, I mean
it's Stephen Hawking brought up the same thing with time travel.
You have if time travel was possible, is possible, will
be possible? When I have we not been visited by
a time traveler. Like it's just kind of a basic,
you know, show me level of of of analysis. Okay,
they're aliens, great, show me one, show me the alien
(15:46):
put it on the table for me to see because
the time traveler erased our memory, and certainly you could,
you can, you can roll out varying levels of conspiracy
and and explanations on top of it. But you know,
at the at the very root, it's it's a question
of all right, if they're aliens, then we should have
seen them, We should see them, and then you can
you can apply your own excuses as to why don't
(16:06):
we have not Alright, Well, On that note, we're going
to actually call this an episode. We're splitting the SETI
episode up into two episodes, so this was part one.
Part two will publish very shortly, so be on the
lookout for that in the time being. If you have
any kind of feedback on part one, you can find
us on Facebook and you can find us on tumbler.
We are stuff to blow your mind on both of
(16:27):
those and we use the handle blow the Mind on Twitter,
and you can always drop us a line at below
the Mind at Discovery dot com. For more on this
and thousands of other topics, Is it how Stuff Works
dot com
Welcome to stuff to Blow your mind from how Stuff
Works dot com. Hey you welcome to Stuff of all
your mind. My name is Robert Lamb and I'm Julie Douglas.
And you know, when you look at space explorestion, you
know we're looking outward, but then there's also a lot
of looking inward. Um. It's just about anything humans do.
(00:25):
You can sort of make a case for the selfishness
of it and the self absorption of it. So we
look out into space because we want to know something
about ourselves. A lot of the times we want to
know what's out there because we want to know where
we fit in. We want to know if there's intelligent
life or life out there at all, because that puts
who we are and what we are in some level
of perspective. And that's one area where set comes into play,
(00:48):
the search for extraterrestrial intelligence. Right, So, as long as
there have been humans, um, there has been this question
of are we alone in the universe? Because you can't
help but look up in the night sky and say,
is that it? You know? Is there? Are we unique?
There are all sorts of questions that roll out here. Now.
Of course, astrophysicists astrobiologists, um, astronomers are all trying to
(01:11):
answer this question, and they're looking more though, in the
infancy infancy of really this possibility of intelligent life. And
when I say infancy, I'm talking more about Mars and
the possibility of microbial life there, or Jupiter's moon Europa
and the presence of water underneath the frozen oceans, or
liquid hydrocarbon lakes on Saturdays moon Titan. So we have
(01:36):
to look there first because we know that those are
sort of the building blocks of microbial life, which then
evolves into something more significant or complex, I should say. So,
of course this leads to this question of well, are
we really unique? Um? Is life the flora and fauna
on Earth unique to us? Is that it? Um? And
(01:56):
this is a huge question and we have to unpack
it a little bit. Yeah. I mean, as we've discussed before,
when when you're talking about life, I mean, ultimately we
have the one model to go on. So we inevitably
we keep coming back to that, what is life and
so stuff on this planet? What are the parameters for
life as we have seen it so far as we
know it? And uh, and what are what's the chemical
(02:19):
formula for what is required, what elements? When do we
need to look for? It's uh, I often think about it.
It's kind of like um, shopping for a new house.
You know, you're looking at all right now, what what's
what kind of neighborhood do I want to live in? What? What?
What do I need to be close enough to? What
resources need to be nearby to make it agreeable? What?
What type of neighborhood is is too hostile to me? Uh?
(02:40):
You know, like one one area is going to be
too fancy, too too rich, just excluding completely another area, uh,
might be a war zone. You know. We have to
say to take all of this into into account even
when we're looking for extratrustrial life, because we're looking at
where where else could life exist more or less like
it exists here, You're right, So we really have to
(03:01):
turn to ourselves. And we know that the chemical composition
of earth face life consists of hydrogen, carbon, and oxygen.
So that accounts for more than of the atoms and
the human body and in all other known life. So
of those three, carbon is really the star of the show,
since it can bond with itself and other molecules really easily,
and it's a very strong bond. Now, if you kind
(03:24):
of take the lens here from from humans and um
and another life on Earth, and you sort of go
out a little bit into the universe, what do you find?
You find the most common elements in the universe are hydrogen, helium, carbon,
and oxygen. Okay, So what is this saying. This is
saying that, uh, life is not chemically special, especially if
(03:48):
you consider that the basis of it can be easily
found in the universe and then harnessed here on Earth.
And if life on Earth were composed primarily of manganese
or molly bendum, then we would have excellent reason to
suspect that we're something special in the universe. But it's not. Yeah,
all this stuff is everywhere. It's kind of you know,
(04:08):
it's kind of like you know when you you're a
certain age and you find this book that you really
dig and you're like, oh, my goodness, is it the
most n album? Say it's an album by a group,
and you're like, how this is the most precious thing? This?
I love this, this album in this book so much.
It speaks directly to me. The artist is speaking directly
to me, and only I can really appreciate it in
the way that I'm appreciating it now. And then you realize, oh,
it's a nation nationwide bestseller, or it's it's on the
(04:31):
top ten Billboard charts, or you know, the went triple
platinum or whatever, and you realize, oh, actually, this appeals
to a lot of people, and I am not special
in liking it. Yeah, and you discover that it's playing
throughout the universe, right, the same music, and it's the
same elements, those same ingredients that make us that are
out there in the stars. But we've talked about this before,
because you've talked about if his start implodes um, you know,
(04:52):
it's throwing out all sorts of material into the universe.
And you know, there's that the great quote by Lawrence
Cross says, you know the atoms in your right hand
are in your left hand all came from that one
star exploding. So it makes sense. This is this is
the stuff that's making that soup. This is the base
of the soup. Um. And if you take that logic,
(05:14):
then you start to say, Okay, it's not unique. This
is a recipe that could be executed elsewhere on the universe. Yes,
But of course the thing about recipes. Um, so we
all know is that it's it's not merely enough to
know what goes in, but you have to know, uh
what amounts going You need to know is it is
it a tablespoon of salt or a teaspoon of salt?
(05:34):
Um makes the world of difference. Um, are certain substitutions allowed,
which ones are not? How are you heating it? How
are you preparing it to make all the difference in
in the ultimate outcome of the recipe? And likewise there
is a lot of that to take into account, just
chemically with with Earth and life on Earth. In his
book The Autographs, Diyson points out the oxygen thing. You
need a lot of free oxygen and that needs to
(05:57):
be supported by some sort of a system on our
planet's ported of course, by all the vegetation that we
we have on this planet. So you have to have
the right circumstances in place to allow the right chemical
situation to be in order. So evolution is kind of
like the baking time, right. So if it takes ten
billion years for a planet become hospitable, then that's ten
(06:18):
billion years of baking time. And so you have to
consider that when when we're talking about exo planets, and
we're talking about them being just the right distance from
the star or um from a sent or a moon
to have the correct elements there for the baking. Right,
that's just one aspect of it. But again, the ingredients
for the recipe your out there, which makes it so
(06:40):
tantalizing of a question of whether or not there exists
other life and intelligent life at that UM. Of course,
we had to go back to something called the Copernican principle,
uh to really sort of understand how life may not
be that special in the first place. Yeah. And then this,
of course kind from should say chemical life. Yes, this
(07:02):
of course comes to us from a mid Polish astronomer,
Nicolas Copernicus. Um and uh. And basically the whole deal
here is that we're nothing special, and that you cannot
enter a scientific analysis of the universe with the idea
that we're something special. There are a number of different
(07:23):
things that spin off of this, For instance, UM. In
nineteen seventy four, astronomer Brandon Carter tackled the quandary of
our anti anthropic coincidence, the idea that there are a
number of coincidences that supposedly make life on Earth possible UM,
and he hypothesized that these coincidence are part of the
universe very structure, and the chance has nothing to do
with it. He proposed two variants, the most important what
(07:46):
we're talking about here is the strong anthropic principle UH.
And in this he drew on the Copernican principle UH,
which again states that there's nothing special or privileged about
Earth or humanity. Uh. We live in a universe capable
of supporting life than than only life supporting universes are possible.
You can really go down the rabbit hole with this,
But essentially it's about putting aside any idea that we
(08:09):
are special. Again, the the the album is a hit
around the universe that the building blocks are out there. Uh.
We can't enter into any kind of an analysis of
or even of a pondering of life else where in
the universe if we're thinking that we're special in some way. Yeah.
And what I really like about the comparonic in principle
(08:29):
is that it does show an evolution of understanding of
our place in the universe, because you know, Comparnicas of
sitting there saying at a time where everybody was thinking
the opposite is saying, hey, the Earth is not the
center of our solar system. And so, of course that
was a crazy thought at the time. Yeah, because for
the longest, Yeah, Earth has to be the center. We're
the center God's blessed creation. So we should be right
(08:54):
there at the center. How can this whole thing not
be about us? Right? We are it right? Um. But
then there's this idea that evolves even more like, okay, hey,
well we're not the center of the Solar system in
the Milky Way, by the way, our Milky Way, our
galaxy is not the center of universe. In fact, we're
not quite sure what the center is. Is there a center? Um?
So you really do see this, This understanding become much
(09:15):
more complex and nuanced as we get more and more
data from the world around us, because now we understand
that Earth is just one of billions of planets that
are all bathing in the same sort of primary chemicals. Um.
So that gets us to this area called the Drake equation.
So we really have to talk about this before we
(09:36):
can even sort of say, okay, we'll do aliens exist,
How would they exist? How would we contact them? All? Right,
We're gonna take a quick break and when we come
back even more on the search for extraterrestrial intelligence. Yes,
(09:57):
the Drake equation. So the Drake equation is pretty widely known.
It's been spun off into a number of interesting little
side projects, like there was a there's a really good
episode of This American Life where that's a team of
scientists try to use the Drake equation to determine whether
they have a true love match out there in the
world waiting for them, as opposed to is there another
(10:18):
life form or other life forms elsewhere in the galaxy. Yeah,
because I want to say this just at the front here,
that the Drake equation is not something that is solvable.
It is it's really about probabilities and how to organize
our thoughts about the data that we have in the
missing data. Yeah, it's about taking the one big question,
the one big probability is their life else from in
(10:39):
the universe, and breaking it down into smaller questions, smaller
probabilities that we can tackle individually. So the entire equation
looks like this, and and this is not gonna all
make a lot of sense, but just in the in
the in the interest of getting out there, it is
in equals our star multiplied by F sub p multiplied
by in sub multiplied by F sub F sub l
(11:02):
multiplied by F sub i multiplied by F subc multiplied
by capital l. And so all those numbers must by
together help us to estimate the number in of technical
logical civilizations that might be able to detect us right now. Now,
if you guys all bear with me, let me unpack
that a little bit, because I do think it's interesting.
Um our star is the rate at which stars have
(11:23):
been born in the Milky Way galaxy over the last
few billion years. That stars per year, okay, And then
all the f factors in this are fractions. So F
sub p is a fraction of stars that have planets,
and sub e is the average number of habitable planets
in any planetary system. F sub l is the fraction
of planets on which life actually begins. F sub i
(11:45):
is a fraction of all those life forms that develop intelligency.
How this becomes Tinier and jiner um. And then F
sub c is the fraction of intelligent life that develop
a civilization that uses some sort of transmitting technology. Finally, L,
which is really important here, and we'll talk more about
this later l is the longevity factor. On average, how
(12:06):
many years do those transmitters continue to operate, because, as
we know, civilizations come and go. Yeah, Like I kind
of like to think of it in terms of a
video store, like you know, and some of you may ask,
what what what is that? Because they are starting to
disappear more and more. But like in the Atlanta we
have this really cool video store called Video Drome. I
still like to go there just to brows around for
(12:27):
nostalgia and nothing else. But you know, I walk into
a video store and I have, you know, X number
of videos at my disposal for possible rent. But then
you have to you have to carve that down all right,
of all the videos here, I can only check out
ones that are checked in, so that dude decreases the number.
Then maybe I'm only interested in seeing an English language
film because I don't want to read subtitles tonight, So
(12:49):
then we have to cut that down. Then I must
say I'm only interested in seeing a horror movie, so
that cuts it down even more. And then I only
interested in seeing a horror movie that I haven't already seen,
so that cuts it down even more. And again you
just get down to there are x number of films
that I could potentially rent this evening. Now, what I
think is cool about this dract equation is that, yes,
there's no righting answer right now, and this is just
(13:11):
a way of organizing information because a lot of it
does depend on who's plugging in the data and why
right in the same way that my data I plug
into this video drum equation could be different one day
from the next. The deal is, though, is that astronomers
are actually getting at this equation right. They've already tried
to figure out about three of those different fractions, So
they're trying to figure out the fraction of stars planets,
(13:33):
the average number of habitable planets, and the fraction of
planets on which life actually begins. So they're getting to that.
So when I talk about exit planets that are habitable
and that goldilocks not too hot, not too cold, that'
from one aspect of it that they're beginning to collect
data on um and they're beginning to say like, okay, well,
now we can get these chemical signatures and try to
(13:55):
figure out, you know, how much carbon is being produced there,
how much method sane which you know something we'll talk
more about as pretty plentiful here on Earth, and that's
a that's a huge signal if there's something going on
on that planet, right probably probably cows as well as
other you know, factors that that create methane that I
(14:16):
won't go into. Uh, But anyway, my point is is
that yes, this is, uh, this is somewhat of a
thought experiment, but astronomers are scratching away at it and
they're getting some concrete information in there. Yeah. Um, I
mean historically whether the estimate the results have varied again
depending on what's going into it, and they varied from
there being one one but one civilization out there two millions.
(14:38):
So yeah, right, Again, there's a lot of data that
needs to be plugged in here, but astronomers are if
if you will, plugging away at that. Now, I wanted
to mention the Fermi paradox, and this is something I
want you guys to all put in your back pocket
as you consider all the other information that we talked
about today. The Fermi paradox is from the Noble Prize
winning physicist and Rico Fantom and he reasoned that if
(15:02):
it takes life billions of years, should develop intelligence and
signal or travel to the stars. And if there are
billions of worlds in the universe, and if the universe
is over thirteen billion years old, then why haven't we
been visited by an extra terrestrial or why isn't the
galaxy crawling with extraterrestrials. This is something we'll get too later.
(15:25):
But that's that's a good question, right, yeah, I mean
it's Stephen Hawking brought up the same thing with time travel.
You have if time travel was possible, is possible, will
be possible? When I have we not been visited by
a time traveler. Like it's just kind of a basic,
you know, show me level of of of analysis. Okay,
they're aliens, great, show me one, show me the alien
(15:46):
put it on the table for me to see because
the time traveler erased our memory, and certainly you could,
you can, you can roll out varying levels of conspiracy
and and explanations on top of it. But you know,
at the at the very root, it's it's a question
of all right, if they're aliens, then we should have
seen them, We should see them, and then you can
you can apply your own excuses as to why don't
(16:06):
we have not Alright, Well, On that note, we're going
to actually call this an episode. We're splitting the SETI
episode up into two episodes, so this was part one.
Part two will publish very shortly, so be on the
lookout for that in the time being. If you have
any kind of feedback on part one, you can find
us on Facebook and you can find us on tumbler.
We are stuff to blow your mind on both of
(16:27):
those and we use the handle blow the Mind on Twitter,
and you can always drop us a line at below
the Mind at Discovery dot com. For more on this
and thousands of other topics, Is it how Stuff Works
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