Kind: captions
Language: en-US
- [Instructor] This video
is about optimistic,
pessimistic, and my own estimates
of how many intelligent
alien civilizations
might be out there.
I center this video
around the Drake equation
that combines a bunch of parameters,
multiplies them together,
and then estimates
based on that the number
of alien civilizations
in our galaxy, the Milky Way galaxy
and the observable universe.
In general, this video's
probably less about
the estimates themselves
and more about the mysteries
behind the very question.
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Okay, the Drake equation
combines several parameter
added in eighth one here.
I'm not using the symbols in the equation
because it's too easy for people to forget
what each one stands for.
The variables build on each other,
hence the multiplication.
Okay, they are the number
of new stars born per year.
The percent of those
stars that have planets,
the number of habitable planets per star,
the chance of life developing
on one of those planets.
Then the chance of
intelligent life developing.
And finally, the chance of
that intelligent civilization
advancing far enough to
develop the technology
to be able to communicate,
in our case through
electromagnetic signal.
Seventh is the lifetime
of that civilization
while it's in the communicating
stage of its development.
And finally the eighth parameter
that wasn't in the original Drake equation
is the average number of times
that a civilization is born
on a planet.
That is one time it's born
and it becomes completely extinct,
and is reborn again.
This parameter makes sense since
the age of a planet can
be billions of years.
And then you multiply it all together
to get the estimated
answer to our question.
I list today's estimates
for the optimistic and the pessimistic
based on the most recent
publications that I'm aware of.
And today estimates for me based on
how I'm actually feeling today.
This estimate probably drastically changes
from day to day or from
hour to hour within the day
based on my optimism on
several of the parameters
I'll talk about.
I should say that the optimistic
and the pessimistic estimates
don't reflect the best
case and the worst case,
they simply reflect reasonable estimate
for a high value for these parameters
and a low value for these parameters.
Okay, the number of new
stars born per year.
The pessimistic one is 1.5,
and the optimistic is three.
I tend to side with the three.
The 1.5 to three stars per
year is the latest estimate
as of about five years ago from NASA.
Most recent relevant paper
that I'm aware of is in 2015.
Either way, the variability
on this parameter is not very large,
just wait until later.
Okay, the percent of
these stars with planets.
This is a little bit tricky,
but it seems to me as of 2012,
just looking at some papers,
almost everyone seems to believe
that now pretty much all
of these star systems
have planets around them.
Somebody's probably gonna
argue for the pessimistic one
being decreased to 90%, or
even the previous one of 30
or even 20%.
I don't think this affects it that much.
The evidence seems to indicate
that pretty much every star
has a planet around it.
I like big rocks and I like gravity,
so I think this is pretty exciting.
The number of habitable planets per star.
This is where we start to
get into some fun debate.
Probably mainly centered
around the word habitable.
Like what does it mean for
a planet to be habitable?
The argument for the optimistic view
is it's pretty simple to be
in a habitable zone of a star
if it's all just about the range
of distances from the star.
The more interesting argument for me
that I tend to hold is
that in order for a planet
to be habitable, meaning support life
in the broad definition of what life is,
the planet doesn't necessarily
need to be earth-like.
There could be totally
different kinds of planets
that are able to support life
that we're not even aware of.
Those who argue for the low estimate,
like the general set
of ideas behind the rare earth hypothesis
that you should check out places
a lot more constraints on habitability,
like suitably low radiation,
high star metallicity,
which by the way, from an
astronomer perspective,
a metal is anything that's
not hydrogen or helium.
So carbon is a metal, there
you go, fun facts with Lex.
Okay, continuing the list of constraints.
Low enough density to avoid
excessive asteroid bombardment,
and there's much more,
there's a long list.
I don't know which one of these
is most constraining to be honest,
but it really centers
around the question stated
by the rare earth hypothesis.
Does a habitable planet
really have to be earth-like?
And exactly how close to the
precise conditions of earth
does it have to be?
Next parameter is the
probability of life developing
on a habitable planet.
This parameter to me is super exciting,
especially because it is one
of the biggest open questions
within the reach of science.
If we discover hard evidence
of life on Mars, for example,
even if it's extinct, or on Europa,
the icy moon of Jupiter.
And maybe more concrete
evidence about life on Venus
that was recently
discovered in gaseous form
in phosphine I think in the atmosphere.
So if there is some good concrete evidence
of life on another planet,
that shows you that the probability
of life developing is quite high.
So the day to day
variability in my estimate
has to do with how optimistic
I am about us discovering life
on the planets or moons
in our solar system.
Going by recent papers,
the optimistic is 13%,
the pessimistic is .1%.
I go somewhere between those all the time,
sometimes much closer to 13%.
Today it's 1%, we're the 1%-ers folks.
But the argument I think
for the high estimate
is that life on earth appears
to have started quickly
after conditions were right for it.
So if it started super quick on earth,
maybe it's pretty easy
to start when the conditions are right.
And the conditions would be right
if we passed the previous parameter
of it being a habitable planet.
Again, these parameters
stack on top of each other,
meaning they're conditioned
on whatever the thing
that the previous parameter
represents being true.
If we stick just on
earth for our evidence,
then the argument for the pessimistic view
is that there doesn't seem to be evidence
of a biogenesis with the
origination of life occurring more
than what's on earth.
As far as I could tell, I
did not see any good evidence
that life sprung up on
earth more than once.
Meaning evidence of very different kinds
of ancestor organisms.
All right, now we're
starting to have some fun.
(Lex laughs)
The probability of
intelligent life developing.
This is of course probably wanna talk
a lot about in the context
of artificial intelligence.
Optimistic estimate I've seen is 1%,
and the pessimistic one is .1%.
I tend to actually see this
as pretty high probability.
In fact, I think that once life starts,
intelligence is basically 100%,
it's almost inevitable
if given enough time.
The open question to me
is how long do there have to be a range
of stable conditions that
support the evolution of life?
And what precisely that range
is once life gets going?
In general, the argument
for the higher value
is that the complexity
of systems seems to increase effortlessly.
And the argument for the lower value
is that humans are allegedly
the only intelligent species
on earth among a lot of the species
that have lived here.
So it may be quite difficult
even for the evolutionary process
to create something like the human brain,
which I do think is
quite a special creation
despite its, in my case,
occasional manifestation
as dad jokes on Twitter, okay.
Oh and I don't
(Lex chuckles)
understand the optimistic estimate of 1%
that I saw in a few places,
so I doubled it to 2%,
that's where I stand on the probability
of intelligent life developing,
there you go, double it.
Okay, ability to communicate.
I kind of think that this is the percent
of civilizations that become
technologically advanced.
In a more general context,
of building advanced technologies.
And I tend to see
communication as bigger here
than maybe the original
Drake estimate did,
in that it's likely
to go beyond electromagnetic
communication,
something that we're not
even aware of currently.
So the argument for the high value here
is that, again, systems seem
to increase in complexity effortlessly.
So, it seems to me that tech
advancement is inevitable
once you have a sufficiently
intelligent civilization.
The arguments that I
find somewhat interesting
for the more pessimistic estimate
is that civilizations perhaps
in time tend to isolate themselves.
They perhaps lose interest in colonization
just broadly in the whole task
of exploration and communication.
Another idea is that possibly
there is a divergent methodology
to the ways that intelligent civilizations
might communicate,
and so there might not be
intersection about them
being able to communicate with each other,
like totally new ways
of information transfer
that we're just not
even aware of currently,
which does not involve any
kind of leakage of signal
that would nevertheless
still be detectable.
So I tend to be on the optimistic side
of communication ability developing
with the 20% estimate.
Next is the lifetime of the civilization
once it's already in that communicating
advanced technology stage.
I think this is one of
the more interesting,
one of the more open parameters
that basically changes the
game in the final estimate.
This is where the most
variability comes from.
The previous parameters I find inspiring
is the scientist and engineer.
This parameter I find inspiring as a human
because the higher we can get it up
as a human civilization,
the more likely it is
that we make extensive,
deep, meaningful contact
with other intelligent
alien civilizations.
So, the optimistic
values here are very high
and they range all over the place.
But it centers around
the idea that there's one
or multiple great filters,
and once we get past them as
a technological civilization,
then we're basically immortal
from a civilization perspective
that we will increase
in the colonized space,
I guess diversifying our use
of resources such that it becomes
increasingly more difficult
to destroy ourselves
through the various existential
threats that we face.
The pessimistic estimate.
If we look at human civilizations.
An average case, and
assume we destroy ourselves
within a couple of years.
Then for humans, the stage
of advanced technology
has only lasted about 100 years
when we were able to send out
explicit electromagnetic signal.
Of course, I don't think we
chose to do so explicitly
until maybe a few decades ago.
I don't remember, I think it was the '70s.
"Stairway to Heaven" Led
Zeppelin era, there you go.
My estimate, to be honest,
in terms of the survival
of human civilization
is almost always pretty optimistic.
The actual estimate of the lifetime
ranges all over the place.
I think my current estimate
is put at 10,000 years.
I think even that really far away,
you know, that's 100 centuries from now.
We're just in the first 100, 150 years
of our advanced technological development.
And what's going to happen
in the next 100 of those,
especially given that
the rate of innovations
seems to be accelerating.
The essentials of my optimism
is grounded in the fact
that the forces of good
will be able to out-innovate
the forces of evil.
Now what that looks like
10,000 years from now
is impossible for me to even imagine,
so I'm uncomfortable with an estimate
of one billion years from now.
So that's why I put my optimistic,
but not too optimistic
estimate of the lifetime
of advanced technological
civilization at 10,000 years.
We're 100 years in, 9,900
year to go to prove me wrong.
And finally, this extra parameter
of the number of times a
civilization is born on a planet.
Given the age of a planet
and if it is habitable,
then I think, and some
optimistic estimates think that
it's possible for intelligent
civilizations to be reborn
on a planet and put that value at three.
The original estimate of course
was a part of the Drake equation,
so it was at one.
And so that's the pessimistic estimate.
Okay, so we multiply all these together.
Of course the percentages
are treated as fractions.
So 13% is .13, for example.
And the result of that multiplication
is the estimate of intelligent
alien civilizations
that are capable of
communicating in our galaxy.
And so for these three estimates,
the result is 468,000 for
the optimistic estimate.
Very very close to zero for
the pessimistic estimate.
And 0.7 for my estimate.
Now that's for our Milky Way galaxy.
Interestingly enough,
the estimates for the number of galaxies
in the observable universe
seems to be changing
and growing actually.
And the current estimate
that I'm aware of is actually
two trillion galaxies,
which is a very high number.
So if we look at the number
of alien communicating
civilizations in the universe,
it's 940 quadrillion,
which is 1,000 trillion
for the optimistic estimate.
It's 300,000 for the pessimistic estimate,
and 1.4 trillion for my
estimate as of this hour today.
Obviously there's quite
a bit of variability,
and I find it quite entertaining
that my estimate landed
on very close one, which
aligns well with the idea
that if we're pretty average
and the Milky Way is pretty average,
that we just may be the only
ones in the Milky Way galaxy,
but every galaxy's got one.
There's a bunch of takeaways
I have from this quick thought experiment.
And the reason I made the video
is I wanted to go through
the thought experiment,
provide my estimates,
and also reason through
the very question itself,
and some of the open
questions around the estimate.
So my current view is that we're not alone
in terms of communicating
alien intelligent civilizations
in the universe.
But the sense I have in terms
of the very concept of communication
is that we don't yet have
the tools and science
to understand what it means to communicate
with alien intelligence.
I tend to believe that
aliens are very unlikely
to have the humanoid form.
That much more likely, the variety of life
is greater than we imagine and
greater than we can imagine.
Some of the variability would
perhaps invalidate entirely
the very structure of the
Drake equation itself,
which makes a lot of
cosmological assumptions.
Life could exist in different dimensions,
whatever the heck that
would even mean for a physics perspective.
As Carl Sagan talked about,
it could exist on very
different time scales
and very different spacial scales,
which would make
communication to us appear
like I think Sagan said, like
noise because of our tools,
but also because of the
human-centered perspective
we have on intelligence,
that we're just not accustomed
to trying to detect signal
that operates on a different time scale
and even on a different spacial scale.
And not just life itself.
I think the variety and
extent of intelligence
and communication methodology
is greater than we can imagine
and greater than we can imagine.
Intelligent beings could operate
at different conceptual spaces
or layers of abstraction.
The nature of communication.
I think for humans it's
in a space of ideas.
It could be in a space of experiences,
or it could be in the space
of whatever lays behind
consciousness, for example.
Consciousness itself may be
aliens communicating with us.
I mean, from the current
scientific perspective,
all of this sounds pretty crazy.
But if you step away and just
think from first principle
of how little we actually understand
about the basic nature of the human mind,
then you have to think
that understanding our mind
may unlock some totally
new ways of communication
and unlock our understanding
of what it means to be an
intelligent civilization
that would totally transform the estimates
provided by the Drake equation.
And that's why I think
it's really inspiring
to scientists, engineers,
and just curious minds,
that the pursuits maybe in my field of AI,
and perhaps eventually the field of AI
starts encompassing the concepts
of artificial consciousness.
I think that provides the opportunity
for both the scientists and the engineers
to understand the human mind,
and to build artificial versions of it,
artificial general intelligence.
And that seems to hold the key.
And that is an engineering problem,
is a scientific problem,
it seems to hold the key
for us to be able to better understand
what kind of other
intelligent civilizations
might be out there.
Again, that's super
exciting, because in a sense,
understanding ourselves
is one way to search
for intelligent civilizations out there.
And in general as I had mentioned,
I think all, or at least
most of the parameters
in the Drake equation can be
illuminated through science,
and through our engineering pursuit.
So if we discover life
on Mars for example,
that shows that life is doable elsewhere.
If we are able to build
artificial general intelligence systems,
at least to me that shows
that intelligence is doable elsewhere
other than the human brain.
And as a society, if we're
able to avoid existential risks
that are before us today,
I think that shows that
survival is doable elsewhere.
Okay, looking at point three,
four, and five quickly.
Let me say that this whole idea
of other intelligent alien
civilizations out there
is really exciting and inspiring to me,
so I hope that governments, nation states,
will be able to look at the
search for intelligent life
not as a threat, not as something
that you keep as a secret,
but as something that can inspire us.
I think we're humans first
and Americans second.
We're curious descendants of apes,
and I think that idea
of threats and secrecy
I hope will become an outdated concept.
But of course, it's not just about hope.
You have to work hard to make it happen,
you have to have actual
practical ideas how we get there.
Because right now the old systems
are stuck in this place
where it's nice
to have superpowers
fighting against each other.
It was the Soviet Union
and the United States,
maybe the 21st century we define by China
versus the United States and so on.
I think it's possible, and I
think we have to build systems
that move us beyond that.
I think for point number four,
I think doing so is essential
for the survival of the human species.
Again, that's my current view,
but I think about this a
lot and I go back and forth.
It mostly has to do about,
at least my thinking,
on how much evil there is in the world.
And right now, for a time at least,
I'm quite optimistic
about the fundamental
good in human nature.
And finally, of course,
in terms of increasing
the lifetime of human civilization,
but in general, finding
intelligent life out there.
I think space exploration
is really exciting.
Generally this whole topic,
the reason I made this video.
The reason I have sometimes
these conversations about aliens
is I do believe that science
is the best tool we have,
but we can still have an open mind
to the mystery of the universe around us.
And of course, to me the most fascinating,
the mystery of the human mind itself.
So clearly, this particular human mind
has to apologize for the probably
too long boring rambling about aliens.
But I hope for the few
of you still listening
that it was at least somewhat interesting.
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Thanks for tuning in, see you next time.