Grabby Aliens and the Fermi Paradox: Why We Had to Be Early
Humanity might not just be early to the universe… we may have to be early.
In this episode of Entropy Rising, we dive into the Grabby Aliens theory, one of the most fascinating solutions to the Fermi Paradox. The idea is simple but unsettling: if intelligent civilizations tend to expand across the stars, then any civilization born too late would never get the chance to exist at all.
We explore:
• Why expansion may be a natural outcome of evolution
• How civilizations could spread across the galaxy in only a few million years
• Whether Dyson swarms and megastructures should already be visible
• The link between Grabby Aliens and the anthropic principle
• Whether advanced civilizations would preserve primitive life or consume all available resources
• How this theory compares to ideas like the Zoo Hypothesis and rare life scenarios
If the universe is full of expansionist civilizations, then humanity may not just be one of the first civilizations.
We may be forced to be.
Website: https://www.entropy-rising.com/
1 And I think a good analogy would be, like, what are the odds that
two independent, not related intelligent species would evolve on
the same planet at the same time?
pretty unlikely because by the time that first species evolves, they're
probably going to build tools and, take over the entire
planet like humans did much, much faster than a second intelligent
species, uh, could also co-evolve along with them, assuming that they weren't,
you know, splitting from the same genetic tree.
Hello, welcome to Entropy Rising, a podcast all about science and futurism.
I'm your host Jacob, and joining me, of course, is the ever
so wonderful co-host Lucas.
Thank you so much, Jake.
Yeah, I love, I love that you think I'm wonderful.
Always.
always.
So for today's episode, we're diving into, uh, quite a fascinating theory.
So this is one of the potential solutions to
the Fermi paradox, the Fermi paradox of course being the
question of, given how big and old the universe is, where is everyone else?
Why are we here alone?
So this theory or solution for the Fermi paradox is known as greedy aliens, and
it effectively tries to explain that we're early in the uni- It effectively
tries to argue that we are alone in the universe because we are one of
the first civilizations to evolve.
But it takes it a step further than that and says that not only are we
the first civilization to evolve, but we must be the first civilization
to evolve, or we wouldn't exist.
So we're gonna dive into this, and I think it's gonna be a fascinating episode.
I think so as well.
that big distinction of giving us an idea that this has to be the reason
why we are one of the first is what separates it from some other theories
that also put us in the first.
So I think it's gonna be really cool to dive in and, um, think a
little bit deeper into that concept.
Yeah.
And I think that is something that's interesting about this one because there
is always the possibility that we're the first because of random chance.
There's always random chance and,
and I've heard that argument before too.
I am particularly drawn to this one because it's not just we're the first
because we happen to be the first, which of course is perfectly possible.
Mm-hmm.
Uh, but it does go and take it a step further.
So Lucas, would you like to jump in and explain the greedy aliens
theory, or would you like me to?
No, no.
Yeah, I can jump in.
So the way that the greedy aliens essentially works is that it is under
the assumption that life, gets to a point to where they can go out into the
stars will want to constantly expand, take over the resources and use them to,
build into their civilization.
And because of this, if that was true and life was able to evolve over the
time that ours did, we would have already taken over all of the planets that
could support life that were lesser, and you know,
expand that and make it so that those resources couldn't be used and no
other life would have formed anyways.
Therefore, if we do exist- And greedy aliens is a
probable solution to the Fermi paradox, then the only reason why we do exist
is because we are one of the first Yeah, exactly.
I think that's a key distinction for this theory is it basically argues that
anyone who does exist necessarily must exist from a civilization that was among
the first to exist in the universe.
And the reason being is like what you said, is because if you assume every
civilization is going to be expansionist, uh, and it doesn't have to be literally
every civilization, but just most.
If you assume that there's a tendency for
civilizations to be expansionist, then once you get further into the history of
the universe, then all of the possible new areas for life to evolve will
already have been used up by these, quote-unquote, "greedy aliens".
Mm-hmm.
And I do wanna add a quick note here.
It's called greedy aliens.
It doesn't actually, like, mean that they're horrible,
greedy, warmongering aliens, right?
In this sense, what it means by greedy aliens is they're expansionist
and they use the resources.
They don't just sit on their planet and let the universe happen by them.
They actually go out and expand their borders.
And when we say conquer or use, uh, you know,
the theory posits that they would expand until they ran into another
species where they could cooperate and be very friendly, nice neighbors.
It's just until they bump into another civilization, they're gonna continue
to expand, uh, across the, what they discover to be dead universe.
Yeah.
it, goes by another name, I believe,
is grabby aliens, right?
Yeah, grabby aliens.
Yeah.
So, um, you know, I feel like that better explains it.
And it's a good theory to think about
because when you think of life itself, it is also grabby, right?
life expands naturally, and especially as civilizations get more advanced.
Like, we went from small pockets of civilizations to expanding
across the entire planet.
So it would only, you know, make sense that we would continue
to do that as far as we could.
And that's actually a really important thing that this theory also points
out, is that, yes, the universe is very large, and it takes a long
time to expand across the universe.
However, this theory points out and it argues, I think rather successfully,
that the time it would take for a upstart civilization to actually expand across
their local area of space is much,
much faster than the time it would take for another intelligent
species to evolve from nothing.
Uh, so when we think about it, we've talked about how you could potentially
colonize the entire galaxy with something like von Neumann probes, uh, even not
von Neumann probes, even just biological von Neumann probes, AKA, uh, us.
Uh, we've talked about how you can do that in, uh, maybe half a million years.
Uh, moving at, like 10% the speed of light.
Half a million to about 2.5 million, depending on how,
how fast you can move, whether it's 5% up to, like
50% the speed of light.
But in terms of evolutionary timescales, that's pretty fast.
And I think a good analogy would be, like, what are the odds that
two independent, not related intelligent species would evolve on
the same planet at the same time?
pretty unlikely because by the time that first species evolves, they're
probably going to build tools and, take over the entire
planet like humans did much, much faster than a second intelligent
species, uh, could also co-evolve along with them, assuming that they weren't,
you know, splitting from the same genetic tree.
That's obviously a different story and doesn't apply to universe wide, uh, life.
Mm-hmm.
it is a solid concept because of those reasons that, that we
kind of see examples of it happening on
a smaller scale being our planet.
it definitely is something that's interesting to think about and that
I, I feel could be very, very possible.
Yeah, absolutely.
So another thing to dive into with this, of course, and it links a
lot with the anthropic principle.
So the anthropic principle is effectively a type of bias you always
have to keep in mind, or it's sometimes called the observer effect, which
is that for an observer to exist to question their existence, uh, and
reality around them, then they must, of course, exist an environment that
supports their form of consciousness, of life, in whichever way that is.
And the way that I often see this explained is sometimes people will look
around the Earth and say, "Wow, what are the odds that this whole ecosystem
works so flawlessly, so fluidly?
There's the right amount of oxygen for human life.
There's so many edible foods for human life.
Uh, all these perfect conditions exist for human life.
W- what are the odds of that?" And some people will use that
to, to make an argument for the creator, uh, or what have you.
But this is where the anthropic principle comes in because it also points out
that the very fact that you exist to ask that question means that of course, the
environment you find yourself existing in is going to support that, right?
There could be hundreds of billions of barren planets, but you're only
ever gonna find yourself existing on the, one planet out of that hundred of
billions that could support your life.
And the grabby aliens theory makes that same argument for
us being first in the universe.
Mm-hmm.
Because it argues if you're not one of the first species to exist, then
you never get to exist because all of the available, basically land, all
the available real estate will have been consumed by these grabby aliens.
So the odds of you being a, a new upstart civilization,
young into your evolution, right, like we are, we're only,
Humans have been smart for maybe 10,000 years.
Mm-hmm.
Pretty, pretty early on, on terms
of, uh, evolutionary scales.
So the... If you find yourself being early in your own history of your species,
then you probably exist at the beginning, earlier stages of the universe before any
other life has had a chance to expand.
Yeah.
And I mean, that's, that's a really cool concept to
think about because it lets you kind of
really settle into that thought that, wow, we may be one of the first civilizations
because we are on this planet that offers these resources for life that
are so plentiful, that if there truly were those grabby aliens, that they...
this would be prime real estate, you know,
for them to wanna move to, taking into account, thought that they
are similar to us in structure and the way that they survive.
Yeah, no, absolutely.
And, and just the fact that we're
so early into our own existence kind of also shows that too.
It'd be one thing if we were hundreds of billions of years into humanity, and
we still didn't find any aliens, then we could probably posit that it's not a
case of us being early, but maybe a case of, uh, life just being extremely rare.
But we are very early into humanity as it is, and so it's very likely that this
is just, for whatever reason, the way the universe works out, we are now in
the life-bearing age for our universe, and we're in the earlier stages of that.
And so, you know, it's kinda fun to think about, right?
This theory says that humanity might be first and,
and if this theory's true, we might go on to be one of the,
you know, huge stellar empires, uh, assuming that
this theory is true and it's not just the case that life is extremely rare,
which both can kinda go hand in hand.
Yeah.
So with, with that being said, there are a few
different ways that this could play out.
What are some of the assumptions that would be needed for this theory to exist?
Yeah, no, that's completely fair.
So there are obviously with any Fermi paradox solution, you need to look
at the base assumptions that this theory makes and see if that actually
works for a Fermi paradox solution.
And I've kinda given this overlay a couple of times when we've talked
about Fermi paradox solutions.
Uh, but some of those assumptions rely on, for one, is this a universalizable
assumption that you can make?
And one of the universalizable assumptions that the grabby aliens theory needs
is that life needs to be expansionist.
Or what we should ask is that, is it the case that all life should be
expansionist for this theory to work, and if it's not, does that break the theory?
And so for that assumption, some people may disagree, uh,
I actually think that's fine.
I think that's a valid assumption that this theory can make for two reasons.
Reason A is that at least on Earth and how we understand evolution
to work, it seems like all life probably will be expansionist.
It's just life is opportunistic, and by definition, it oftentimes
tries to expand and find new niches to occupy and adapt to.
And I don't think that that's gonna change on different planets.
I really do think that's gonna be one of the underlying cases for
life anywhere, uh, in the universe.
And I, I feel like we can call that a
universalizable in my opinion.
I don't, I don't know what you think about that, Lucas.
No, I mean, it, it makes sense, right?
Now, of course, we are our own sample size- Of course our,
our planet, but it's not just our civilization.
You see the, like, like resource guarding, resource
collection, expansion, territory guarding are present in, like
hundreds of different species, so we can, of course, make that assumption
unless we meet another civilization that changes that- Of course ... um,
that, that we will want to or that our
life will continue to do that just throughout the universe.
And just thinking about it from going back to basics, just thinking about it in terms
of, of life existing in general, any form
of life that's more expansionist than the life around it is probably gonna
do better in, in Darwin's game of evolution because they're better gonna
be able to expand out, extract more resources, and out-compete, uh, less
expansionist f- uh, versions of life.
So you would imagine any planet that goes through natural selection is going
to tend toward favoring ex-expansionism.
So I do genuinely believe that's gonna be very common, and
that's, that's where I'm basing my assumptions
on, that this is very likely gonna be a universalizable truth.
Yeah.
I mean, it would, it would actually go against all of
the, the facts that we have on life so
far to say that it wouldn't.
Yeah, exactly.
Now, of course, once you start talking about advanced civilizations, things
get a little different because we can kind of separate ourselves from
biology a little bit.
We're thinking, we're rational, a- and there's always the possibility
that species may act differently than just basic biological,
you know- bacteria, right?
Uh, so this kind of brings me onto the second point of is this a valid
assumption, which is point number two.
Even if it's not universalizable, even if it's not the case that
all life expands, that's fine.
You really just need some life to be expansionist to have this theory work out.
It, it only takes...
depends, of course, on the, the density of,
of life and intelligent life in the universe, but even if one in 10 species
are actually expansionist and go out and, and expand, that's fine for this theory.
That doesn't break it at all.
You just need some life to go out and expand, and if that's the case, then this
grabby aliens theory works as long as you don't f- find yourself in a really
rare situation where no life expands.
And, and that's the part where I would
say it starts to break this rule of universalizability because in order
for this theory to not be true, it would basically need to be the case
that no life goes out and expands, and that is, of course, possible.
Either life's extremely rare, uh, so you only get, like,
one life form in a galaxy cluster.
In which case, even if that life's expansionist, it,
it'll likely never encounter other life.
no, I mean, that, it definitely makes sense, but it's
just, uh, it just seems more unlikely.
And like, just like if you were saying,
if only one is expanding, then tho- those other planets could even be left
alone, but the aliens would branch out and they would take everything else.
But even us without being an expanding civilization, we
already have the intention to do so.
So it's like that sample size being 100 just makes that more and more plausible.
I guess another assumption this also brings up is can we actually
expand and explore the galaxy?
I know that's very related to the first point of would you want to.
Mm-hmm.
But it is important to consider could you.
And arguably, that's kind of what this whole podcast is
about, how you would go and move about the stars, and I see no reason why you
can't go and colonize the universe.
I, I know I already mentioned von Neumann
probes, but that's a great example.
We already have an idea with something like Project Sl- uh, Slingshot, where
we could potentially send a probe to our nearest star, Alpha Centauri,
fairly quickly just through some, uh, pusher lasers and solar cells.
So it's not an impossible thing to do.
To expand into the universe.
Can you make self-replicating probes?
Sure, why not?
Uh, because biology can do it, kind of
to me tells us that you can do it with technology as well.
You can design cells, you can design, uh, biological biomechanical
beings if you really needed to.
But there's no reason to think that you couldn't design
self-replicating probes as well.
And even if you couldn't design self-replicating probes, uh, the fact that
you can, get to the same end with biology.
You know, we basically are self-replicating
von Neumann probes.
I know I've read some science fiction that involves that, um, that talks
about that idea, being- Mm-hmm that life was started on the planet
and called out the fact that, uh, that's kinda how biology, uh, behaves.
And so we know that it's, it's perfectly possible to,
to reach other stars.
It, it becomes questionable, and,
and this is fair, if you could build, like
interstellar colony ships and send humans to other stars, but
I genuinely think you could.
And you can also get around that if you really want to.
I, I know Revelation Space touches on it,
and granted it doesn't work out well in that book, but you can also send ships of,
like embryos for example, 'cause those are much smaller.
You don't need to have all the same life support.
Grow them up with something like an artificial womb, and then use
that as a way to expand the galaxy.
In Revelation Space they all go crazy because it turns out you
need parents, which fair enough.
But- ... um, that's just one of the examples of how you could do this.
And I do think you could build a ship that
actually contain humans and get them to another star as well.
Oh, yeah.
Of course.
I mean, we've touched on that topic before.
And, um, like actually going across our entire galaxy and colonizing these
planets, especially if we're using, uh, like von Neumann probes to do it
that are hyper-efficient, are able to,
to colonize and move on to a new planet, Drop people off,
or whatever we are at that point.
Drop us off and then keep going.
we could colonize the entire galaxy, what, in like
150 million years?
Oh, no, no, like, uh, two and a half million years.
Two and a half million years.
Now- I think that's assuming 10% the speed of light.
Okay.
So now think about just, like, how long, evolution has taken for
things to get to a point.
Now, again, grabby aliens doesn't have to be just one.
It could... It would be all the civilizations that
evolved to an expanding point, Around the same time.
And, and, There, there's different
borders could be set up.
But it's just the assumption that you are one of the first.
So you don't even need to have the whole galaxy assuming that on the
other side of the Milky Way there's another civilization similar to us.
You know, we could split it in half.
Uh, but- And that's effectively the argument,
is you continue to expand until you bump into other civilizations.
Right.
So you, you essentially expand, you make those borders.
But We would be expanding so rapidly compared to evolution
that, we would essentially take everything, that would be useful.
Yeah, exactly.
If you are colonizing and terraforming planets as you cross them- Then
the odds of other life forming and, and developing intelligence
is, this theory argues, zero.
Although that's another assumption that we can evaluate too.
Would it be the case that because a civilization is expanding, that it
necessarily means that new civilizations couldn't start within their borders?
And that's, that, that one I question, because
I could definitely see cases where intelligent species like
ourselves, decide not to do that.
For example, number one is that we've made the argument so many
times on this show, it almost gets
gets old, uh, but we don't think living on planets is necessarily
the best way to go about things.
we think that it's very possible you may favor living in orbital habitats,
things like O'Neill cylinders, McKendree cylinders, uh, what have you.
And in this case, planets suddenly become a little less valuable
than I think this theory posits.
Mm-hmm.
And so it's very possible that as you're expanding across the universe, if you
discover a planet that already has life on it, not intelligent life, but just
life in general, that you may decide to quarantine this planet, use it for
scientific study, uh, but allow it to go through its own natural course.
And I think especially if that life is fairly rare, you would, you
might treat these planets as like jewels a- and not jump on them.
And another thing I wanna point out, because I,
I know a critique to that might be, okay, especially if life is rare, if
we come across a biosphere, aren't we gonna wanna jump into that and use it?
Because what are the odds of finding planets that can support our life?
But just because you find a biosphere doesn't mean that
that's gonna be able to support our kind of life.
It could work on very different ratios of gases, even just different levels of
oxygen could make it very hard for us to exist, could be different temperatures,
and it could actually be, uh, harder to adapt a biosphere to support our life
than starting with a sterile planet.
so I don't necessarily know if that's true, that because a civilization is
grabby, quote-unquote, and expansionist, that it wouldn't preserve planets
that are harboring life and allow them to go through their own course.
No, I mean, it, it definitely could.
but At, at what point does that civilization
become a- advanced enough to where, like,
do we allow them to get to the point to where they expand out
into their solar system or to where they can even observe us?
Because if the grabby aliens theory is, we,
we are one of the first because if we weren't, then we wouldn't exist-
Exactly ... at the point that we are now.
And that's why that would break the theory if the grabby aliens don't
just automatically occupy planets and prevent life from forming on them or
intelligent life from evolving on them.
I mean, they could, Like, let's say they, they could allow
life, life to get to the point of how
we were maybe 1,000 years ago.
Because at that point, you know, we didn't really have
the technology to even be able to observe them.
But with how we are now, it's safe to assume that if they had
O'Neill cylinders in our solar system, we would be aware of them.
Yes.
But they, but they don't.
The whole argument for the Fermi paradox is we should be able to detect things like
Dyson swarms in the universe, and we could detect those from a very long way away.
Uh, so obviously as far as we can tell right now, that's
the ca- we don't see that.
We think we're one of the first.
But if we were one of these upstart civilizations in a quarantined planet,
then that would be something different.
And what we really would have to do is explore this in a whole other
episode on the zoo hypothesis, 'cause that's effectively what this is.
but I, I do wanna call out that one
assumption on this grabby aliens theory, and it's always kinda nagged
at me, is that I don't necessarily think you can just call it true that
an advanced civilization would make it
impossible for intelligent life to form on planets that are within its boundaries.
Yeah.
it definitely could be true, and bringing in the zoo hypothesis
is, is great because again, that is another
thing that we do here on, on Earth.
So going off of those assumptions, if we do find something like life, and,
we've talked about this a lot before, but living off planet is gonna be way
more efficient, um, than trying to, survive on a planet.
then I don't see a reason why we wouldn't wanna preserve life and
just, just for observation, scientific study, or just, like,
some kind of futuristic entertainment for,
for public masses to go and visit all these different creatures.
Yeah, absolutely.
Now of course that's assuming you find a planet that already has a biosphere.
It is worth pointing out even cold, dead rocks could eventually harbor
life down the road, so that's kinda the
argument for the grabby aliens theory is even if they're benevolent, uh,
they may deny opportunities for life down the road just because they're
taking these resources of planets that would eventually harbor life.
Yeah.
Uh, so I guess that is also kind of
playing into it too is if you only were to allow planets that already have a
biosphere to exist, then you still might be denying a bunch of opportunities.
And depending on how rare life is, it could be the case that,
uh, you still kinda play into it.
But again, I think that we're gonna have to do an episode on the zoo
hypothesis and dive into that a little deeper, 'cause that could turn into
its whole other episode, and I do think it's a fascinating one to think about.
It is.
And it also kind of draws us into an assumption on
the Fermi paradox as a whole, which of course this being a solution
to is also something to consider, which is could we necessarily
detect advanced alien civilizations?
And essentially the assumption there is that advanced civilizations are gonna
build massive solar collecting things like Dyson swarms, which is something
we could detect from a very far distance even with our current technology.
In fact, we thought we observed one with something like Tabby Star,
which ended up just being a star that was occluded by some dust.
Uh, but the fact that we could even detect that, it kinda gives you an idea of why
we assume we can detect Dyson swarms.
Yeah.
I see some people, they think that,
the aliens would maybe hide that technology from us, um, by some kind
of cloaking or something like that to where we couldn't observe it.
But I, I think that it's a little bit
egotistical to think that they would even care that m- building those
structures, being broadcasted to a civilization, uh, so low beneath them
as ours would be, that they would even be concerned with something like that.
Yeah.
It's always tricky to say, and it's,
it's really tricky to try to guess the motivations of an alien intelligence.
Mm-hmm.
Um, but I could see it going either way.
But I agree with you.
W- it could be the case they just don't care, and when you find
yourself able to detect them, maybe they swing down and say hi.
Uh, but yeah, there's all kinds of ways that you could
get around that, so who knows?
Uh, but I do like that the, this theory posits that
we could be one of the first or...
It actually goes even further.
It doesn't just say that we could be one of the first.
It argues that we are one of the first- Mm-hmm
and we must be one of the first.
Yeah, I agree.
That's why I think that this one is really cool to think about because
by its nature, we would have to be.
And that is kind of... You know, it's lonely, but it's exciting.
Yeah, I like the idea we could be some galaxy-spanning empire, and it's
kind of fun to think about it in this way.
And it does fit with my model of how I expect humanity to function.
I think we're gonna continue to expand out as much as we can
and, and take over any resources we can.
So o- on that sense, I kind of agree with the grabby aliens theory.
And I guess my main critique with it and the main thing that could
counter it and make it not true, I mean,
there's a bunch of other Fermi paradox solutions that could make it not true,
but I guess my main critique with it is that it kinda breaks if you just
believe that life is extremely rare.
Mm-hmm.
That's a perfectly valid alternative and kinda breaks this theory
if, uh, if that is the case.
so a- and that is something I could also see, 'cause I,
I still think that in my head and, like, when I'm, like,
ranking which Fermi paradox solutions
do I think are actually true, I do think the odds of life being just
incredibly rare, maybe again instead of thinking it happens a couple of times
in a galaxy, it might only happen a couple of times in a galaxy cluster.
Maybe we're the only intelligent life, uh, you know,
within a couple hundred million light years of, Earth.
That also, uh, to me just seems like it's very possible.
Yeah, no.
I mean, uh, it's, it's like you said in the beginning of
the episode, random chance is always a possibility, and there is a random chance
that we, that we are the first civilization.
And if that's true, then, you know, there's, like,
the grabby aliens, like, other civilizations expanding
really has nothing to do with that.
it is easier to grab onto grabby aliens, no, no pun intended, because,
They give you this, this definite, excuse as
to why we would be here.
Yeah, no, absolutely.
With that, is there any other assumptions you can think of that
this theory needs that should be evaluated or that we should underline?
No, no, I, I, I think, I think that's about it.
Yeah, so this was a bit of a shorter episode, but it's an interesting
topic to touch on, and, uh, worth evaluating some of those assumptions.
So I hope you all enjoyed it, and I think this sparked us and inspired us to dive
into the zoo hypothesis as a solution to the Fermi paradox for next week.
So if you enjoyed the Fermi paradox and you wanna hear more about it, check out
our next episode when that's released.
Thank you all for joining.
Thank you, guys.
Bye-bye.
Bye.