So, this talk is entitled, “The Far Future
of Intelligent Life Across the Universe.”
But it might also be entitled, “The Surprisingly
Near and the Almost Unimaginably Far Future
of Intelligent Life Across the Universe.”
Or “The SNatAUF Future”, as we refer to
it.
But the Almost Unimaginably Far will be a
brief parenthesis at the end.
But the Surprisingly Near is that it is very,
and please notice the quotes, “easy” to
expand across the universe and colonize every
single galaxy that we could ever reach.
There's two points to the talk.
The fun, technical stuff is the second.
The first is why had nobody done what I did
before when I put together these numbers?
This is arguably the oldest science fiction
book from the second century where people
on a boat ended up on the moon where there
was a war with the empire of the sun and various
things happened.
As you can tell, it's not exactly the hardest
sci-fi that you can get.
But we've had galactic empires.
We've had harder sci-fi and we've had things
that look at, say, the economics or the social
aspects or the environmental aspects across
the galaxy.
But it was a surprise to me that no one had
sat down and said, “Okay, colonizing the
universe, how would we do it?
What are the numbers that we'd look at?”
Robert Bradbury started that.
This is his table on disassembling planets,
but he died before taking that any further,
and I used his numbers with great gratitude.
Especially the one on the planet Mercury.
So this is sort of the first lesson of this
talk, that there are questions out there that
can be analyzed that have not been.
There's still important unanswered questions
that people have a vague, intuitive idea as
to how space colonization might work, but
no one's actually sat down to write it out.
And there's probably gonna be things like
that and things far more near term than space
colonization.
And now on to the sort of second lesson of
the talk that was just really fun, collecting
all the numbers, putting the pieces together
from the different fields of physics and engineering
and seeing what you could do with it.
So, the challenge.
Humanity wants to colonize the universe.
How?
Energy and materials?
Probe designs?
Where do we go?
How long does it take?
The basic questions.
This is going to be using the methods of so-called
exploratory engineering, which means that
we know what we can't do, we know what we
can do, we're kind of going to move into this
nebulous area there.
And obviously, so if we assume, say a few
thousand years, which is in rounding zero,
on a cosmic scale, what could humanity achieve
if we continue as a technological civilization?
Now again, we shouldn't turn to stories here,
but we're gonna use some guiding principles.
The first one is an if it's been done in nature,
we'll be able to do it ourselves at some point.
So I'm assuming some form of AI and some form
of replication will be doable.
'Cause we're really quite good at co-opting
nature or copying it eventually.
And the second thing is that, I'm just going
to assume the task can be automated, that's
something we're really good at.
And what this means is that scale is not an
insurmountable barrier.
Just because something is big, doesn't mean
that we can't do it.
We'll get to that.
So the real limiting factors are going to
be: energy and material, and time.
So, the first thing: energy.
Now, the obvious thing is we have a sun.
Let's Dyson it.
There's various designs for Dyson spheres,
the one you see in science fiction is always
the shell, which would tear itself apart and
would just plunge into the sun if you actually
tried to do it.
Swarm lots of orbiting solar collectors, and
then there's the bubble idea, solar sails
and panels, that are just sort of floating,
using the energy of the sun itself to stay
in orbit.
We're gonna go for the swarm.
The simplest and easiest design.
And here I'm gonna always assume conservative
options.
When I get to the part about disassembling
planets, you may question the use of the term
conservative, but actually the conservative
assumption is that we can take planets apart.
The daring assumption is that we'll have super
materials so we won't need to do it.
But we need a convenient source of material
for this, close to the sun.
Hmm.
As I said, sorry Mercury, it's nothing personal.
But here are some numbers.
The mass of Mercury, let's assume 50 percent
of the mass is usable, mainly hematite oxygen
and iron.
As I said, this is conservative assumption.
We'll probably be able to use most of Mercury
if we get this done.
Useful mass of Mercury and a sphere in Mercury
orbit, using this useful mass, would have
about half of a millimeter thickness.
And that is plenty, 'cause what we're mainly
thinking is huge mirrors.
That's the majority of the Dyson Swarm.
Huge mirrors floating in space, orbiting,
concentrating solar light down on some engine
or some cell that actually does the extraction
of the energy.
And this is, I say, if we allow ourselves
to dream a bit here, and look at more extreme
materials, then we can get much thinner swarms,
which means we could use a large asteroid
rather than a planet.
And the sort of, various Mercury Conservation
Societies, which will no doubt spring up,
will probably be grateful to us for that.
Okay.
In diagram, we get energy.
We mine stuff on Mercury.
We get that stuff into orbit.
We make solar collectors from that stuff.
And we use that to get energy.
And the cycle continues.
And we build mining equipment and factories
as we go along.
The whole, completing the loop, is the main
assumption here.
If you get this loop, you get exponential
feedback.
And then the details don't really matter.
If you don't get the exponential feedback,
you won't be able to take Mercury apart in
any reasonable amount of time.
But if you do get the loop, even if it's an
inefficient loop, you will.
So, what I assumed was that it took five years
to process the material and move it into orbit
and get useful energy out of it.
As I say, 50 percent of the material usable,
a tenth efficiency for moving the material
off the planet.
A third efficiency for solar captors.
And initially, our seed is one kilometer square
of solar captors on the surface of Mercury.
This seed by the way is something that we
could do, I don't know, in 15 years, if the
entire world felt like it.
So, what happens then?
Well, on a log scale, this is the amount of
power that we get.
So for the first five years, nothing happens
because material is just being placed.
Then we get a leap as the first generation
of the Dyson Swarm comes online.
Then a second leap as the second generation
comes online.
The one made by this one.
And then it smooths out gradually.
And I stopped the curve at that point because
if you look at the mass of Mercury, that's
what it's done in the same amount of time.
As long as you can close the exponential loop,
you can can take Mercury apart in, well, this
is completely unrealistic because if we do
this, we would do it in 15 years or less.
We probably won't do it this way.
As I said, we'll probably use large asteroids,
but realistically, if we can get the feedback,
it'll be much faster than this.
So, that deals with getting the energy.
By the way, this made it into the Daily Mail
on one of those infuriating, technically correct,
but completely missing the point, in that
if you read the thing, it was, well first
of all scientists aim to begin projects within
25 years.
I don't know who those scientists are.
I'd like to meet them.
But also, it claimed that this would solve
the world's short term energy problems, which,
yes, it would.
I mean, a nuclear bomb solves your lack of
heat.
This has kind of completely missed the point.
But anyway, we've got there.
Now we need to launch.
And what are we going to launch?
Well, we have various mass drivers, quench
guns, or lasers that we should point at solar
sails from our probes.
I'm imagining a mixture of the two.
And then we launch.
The rocket, by the way, is pointing in the
right direction because it's going to have
to decelerate upon arrival.
What do we send?
Well, we send the so-called von Neumann probes,
self replicating probes.
Here's a design for a von Neumann probe, take
a happy couple, add more happy couples, give
them stuff to eat.
Give them data, manufacturing capability,
add an engine, wrap it all up, and here we
have a von Neumann probe that can eventually
create copies of itself.
Extremely inefficiently, hundreds of tons,
limited acceleration and the speed of replication
is the speed of human reproduction, and maturation.
There are some designs for a self-replicating
lunar factory.
NASA was doing some cool stuff in the 80s.
But if you adapt this design you get a 500
ton payload.
This is far too much, but this is a useful
upper bound for what we might have in mind.
And this is the smallest design, the self-replicating,
Merkle-Freitas HC molecular assembler.
But what I said, and what we're assuming is
that we can co-opt or copy nature.
And in nature, we have vibrio comma, the sort
of smallest general environment replicator
at 10 to the -16.
We've got E. coli, which is much more robust,
the smallest seed is at 10 to the -9 kilograms.
That's interesting 'cause seeds create microscopic
structures and the smallest acorn is a gram.
And the acorn is very interesting because
this is a potential huge factory, solar powered
huge factory for the production of more acorns.
If we copy that design we can sort of give
it a leg up, because we can give it extra
energy at least at the beginning.
Like give it some nuclear power.
You need legs, drills, roots, to extract resources.
Again biology has this so we can assume that
our probes will also have this.
And I'm going for a final mass of 30 grams
for this.
Many people think this is ridiculous, but
it's not clear whether people think it's ridiculously
high or ridiculously low.
Data storage limits, I'll skip over this.
Basically it's that there's ample space to
store as much as we want, including the whole
population of earth as uploads, some compressed
uploads if we felt like it.
Now, decelerating, I'm gonna look at using
a rocket.
What I've recently discovered is that you
can escape the tyranny of the rocket equation,
which I though you couldn't.
If you decelerate using a gun, you can actually
do it more efficiently than if you use a rocket.
If you wanted, in the questions, you can ask
me the difference between using a gun or a
rocket for deceleration.
But the tyranny of the rocket equation is
not... but anyway this was when the numbers,
when I stopped, that it, you had to have this.
So these are the, again, conservative estimates.
This is the relativistic rocket equation.
It is incredibly nasty.
Final mass of that.
And here, basically I'm looking, you need
to decelerate from various speeds, using various
engines.
How much reaction mass do you need to end
up with your 30 gram replicator?
Matter - anti-matter, Fusion, and Fission.
And I'm looking at the three scenarios across
the diagonal.
So this is the amount of reaction mass that
you need to decelerate.
And rounding these up a bit, are model probes
of five kilograms, 15 tons, and 35 tons, entered
at these various speeds of launch.
There's another way of decelerating, which
is basically, don't bother.
The Hubble drag means that if you aim for
the most distant of distant galaxies, by the
time you get there, you'll be moving with
practically no relative velocity.
This also means that for other galaxies, you'll
arrive slower than your launch speed, so deceleration
also becomes easier.
So, I'll also model this scenario.
Now this is where the sort of social, or story
model of science fiction leads it astray.
Colonization is often thought of, well, not
even a galaxy, you start at a star, you go
to another star, you get resources, you spread
across.
This is basically the European age of exploration
ported to space.
But, here's another way of doing it.
Let's go everywhere all at once.
Launch probes to every single galaxy that
you could ever reach.
Small technical details: we might need to
go round the milky way, so some of the galaxies,
you have to go in two stages, but that's a
minor thing.
This is our exponentially increasing universe.
And this is how far we can reach in co-moving
co-ordinates at 50 percent of the speed of
light, 80 percent, 99 percent and 100, well
at light speed itself.
If we allow ourselves to re-accelerate, then
we can go further.
So if we stop and then re-accelerate, we can
go further.
And this is the number of galaxies that we
can reach from a low, if we go at half light
speed of just a mere hundred and sixty million
galaxies to a high of four billion.
These are putting all the numbers together.
The numbers of probes, there's a certain redundancy.
There's a bit I've cut out here, which is
what do you do with space dust?
You need a certain redundancy.
There's a redundancy of 40 for the high speed.
We just need a redundancy of 2 for the low
speeds.
Total energy requirements.
We have our sun.
We've Dyson'd it.
How long does it take to get this amount?
Well, for the worst possible scenario, the
fusion launch, we need six hours of the sun's
energy.
To power the launch to every single galaxy
we could ever reach at these speeds.
And if we go for the 500 ton replicator, it
goes up to 11 thousand years.
Again, we can use more stars if we want to.
We can pause along the way.
Do the old fashioned way.
But again, on the cosmic scale, these numbers
approximate to zero.
So what is going to happen if we consider
that we can expand so easily, hence aliens
can expand so easily.
By the way, the initial impetus of this was
to make the Fermi Paradox much much worse.
Because we don't need to just worry about
why don't we see aliens in our galaxy, but
why have they not come here yet?
And why have the aliens of nearby galaxies
not reached us yet?
Especially 'cause the earth is a late coming
planet amongst the earth-like planets.
Anyway that's another thing.
This, if life is rare, you'll get this, mainly
isolated bubbles.
If that's the case, then this is where we
get to the really far future.
Oh, and that's the scenario where there's
lots of lifes and then we'll have, we'll encounter
them as we expand, and we'll have to negotiate
around the frontier.
The problem there is external coordination.
What do you do when civilizations meet each
other?
There's attack versus defense, what is the
balance when you're in the cosmos?
Can you have better technology at this stage?
Or is pretty much, are you, at least for the
warfare, are you pretty much maxed out?
What about the scorched earth?
If you say, well if you attack us, we'll destroy
our resources, it'll just cost you.
You'll gain nothing.
There's negotiations, extortions, threats,
surrender, there's an interesting dynamic
there.
It's very hard to predict but these are the
considerations that we'll have if there's
lots of civilizations that'll encounter each
other.
In the empty scenario, it's a question of
internal coordination.
How do we stop the different branches of humanity
or descendants of humanity from breaking apart?
This is the amount of mass that we could eventually
reach.
This is that mass taken as a mass energy.
And this is the number of erasures that we
could theoretically do with that amount of
energy.
Now, remember what I said about the very far
future?
Computing is more efficient when it's cold.
If we wait a long, long time.
And by a long long time, I mean trillions
of years.
Don't be so ridiculous, this is, you won't
even notice trillions of years that go by.
But if we wait a really long time, the only
heat that we will get will be from the event
horizon of the cosmic expansion of the universe
itself.
And then the temperature will be extraordinarily
low.
And then if we take all this energy, and run
it, this is the amount of erasures that we
can do.
The Landauer Limit, or the Bekenstein Bound.
One or the other of that.
Erasures are important 'cause that's the thing
that gains entropy.
You can't avoid getting entropy when you erase
stuff on a computer.
So if you have reversible computation, maybe
quantum reversible computations, how often
do you need to erase?
And then that'll give you, by the way, ten
to the one hundred and twenty-two is a very
large number indeed.
I think that's one of the biggest understatements
I've every said.
But this gives you the idea of the amount
of computation that you could theoretically
run.
I say theoretically because we have a problem
getting this mass energy.
This mass into energy, and then waiting that
long.
The problem is that proton decay is just too
damn fast.
Proton decay is on the scale of ten to the
thirty four years or so.
And it seems that the protons will decay before
the black holes start evaporating.
And that is very annoying 'cause otherwise
we could just chuck out all the stuff into
the black holes, wait, and harvest the energy
as they start evaporating.
But this is theoretical maximum.
Anyway, so, this is the end of the talk.
The point of this was, nobody had done these
computations before me and Anders Sandberg
and Bradbury, while he was still alive, did
some of them, and we sort of put it together,
so you can really put together interesting
stuff that is there.
And the second thing is, this is really cool
and shows the potential massive amounts of
value that could exist in the universe.
And if we can ensure that that's flourishing
value, that would be really nice.
Thank you.
Do you wanna take some questions?
Go ahead with the questions, I've been a bit
long.
Yeah, we'll take 'em from here so feel free
to join me here.
Okay.
We'll just do a couple of questions.
And then he has office hours at 10:30.
Yeah, we're gonna try to take 'em on the phone
if that's fine?
Okay.
Okay.
Thanks.
It just picks up better for recording.
Mm-hmm (affirmative).
Yeah.
Questions were sort of brief, so I'm gonna
try to add context but feel free to clarify
if I missed your question.
We had one question, what about aliens?
I think you touched on this a bit with the
external coordination.
So, I'm going to spin that as like, which of
the external coordination problems would you
expect to be most challenging?
Whether there is a principled way of resolving
disagreements or not.
So, whether they, you have to have wars or
not basically.
But we can talk about that more later.
'Cause that's getting esoteric.
Yeah.
Sure.
Someone wanted to hear your explanation of
the difference between using a rocket and
a gun for deceleration.
When you use a rocket, you have to accelerate
or decelerate your fuel that you will then
use to continue to decelerate.
If you use a gun... so in one thing, so, if
you're accelerating the bullet by shooting
the gun, that's all in one impulse, and you
don't get the fuel for the bullet that is
accelerated to the same extent.
You can also, this is probably more realistic,
eject your bullet, have it deploy a solar
sail and then just paint it with a laser from
your gun, and that will avoid the rocket equation
as well.
It's basically, you don't need to... you're
just decelerating the payload, you're not...
yeah, if the payload carries the fuel, you
have the rocket equation.
If the payload does not carry the fuel, and
the fuel is stored in the gun or the rest
of the thing itself, you can avoid the rocket
equation.
It's Eric Drexler who came up with that and
it took me a long time to convince myself
about it, but the equations work out.
Cool.
Thanks.
Yeah, someone else asked what point or points,
I assume during a plan like this, do you place
the greatest probability on a great filter?
And they made reference to the Fermi Paradox.
I put the great filter early, at the very
beginning of life, pre-life or at the very
beginning of life.
If I had to bet, I would bet on, either pre-life
or mitochondria kind of thing, or maybe oxygen.
But, we can talk about that more in office
hours, 'cause there's a lot of interesting
other points there.
Yeah.
And a final question before we wrap up, you
said that science fiction often talks about
the British colonization model, but you think
we might be able to go to many galaxies simultaneously,
is there an assumption then, that you would
have enough energy early on in the process
to do this simultaneous-
Yes.
You just needed ... so for the small probes,
you need six hours of the sun's energy to
launch all the probes to all the galaxies.
All right.
And I mean, and these, yes, we have some slack.
Alright, cool. Unfortunately, we're gonna have to cut it
there.
Yeah.
Thanks so much.
I'll just mention you have alternate designs.
Maybe you just want to hit a single super
cluster, and you can do that with a... so
if you have heavier probes, you can just hit
super clusters and radiate out from there.
There's other designs that you can do.
But you can just blast every galaxy with that
kind of energy.
Cool.
Again, thank you so much.
We appreciate it.
