In our search for extra-terrestrial intelligence we examine the stars hoping to find something
in those tiny islands of warmth amid the vast ocean of night.
But what if we’re looking in the wrong place?
It’s been a bit less than a century since we realized that our galaxy was not synonymous
with the Universe, and that some of the hazy nebula we could see were far larger and further
away than we’d assumed, cousins to our own galaxy.
It took us much longer to group these into clusters and eventually superclusters, and
to see the underlying structure connecting those galaxies, in filaments like a vast spider
web or foam of soap bubbles filled in between with far larger volumes of near emptiness.
We began calling these voids, and soon discovered a truly enormous one that was subsequently
named the Bootes Void or Great Void.
It’s so big, at over 300 million light years across, that there was a lot of doubt if it
could have been formed naturally within the cosmological models of the time.
This inevitably led a lot of folks to wonder if it might in fact be unnatural in origin.
One of the most common questions I get on the channel is if this might be part of a
solution to the Fermi Paradox.
So I thought it was past time we discussed that option.
If you’re not a channel regular, the Fermi Paradox is the apparent contradiction between
how big and old the Universe is, and the seeming absence of any other intelligent life in it.
Or basically, if the Universe is teeming with alien civilizations, where is everyone?
If you are a channel regular then you know that one of our add-ons that further exacerbates
the Paradox is the Dyson Dilemma, the assumption that colonizing space is practical and something
most species will do, and that any star system they colonize, beginning with their own that
they evolved in, should eventually fill up with various habitats, solar power collectors,
and machinery so as to use up all of the sunlight produced by that star, what we call a Dyson
Swarm or Kardashev 2 Civilization.
The Dyson Dilemma doesn’t ask why we aren’t getting any signals when we look at distant
stars, it asks why we can see any other stars at all.
As long as it takes to colonize a galaxy, it’s very little time compared to the age
of those galaxies, and a very long time compared to even fairly anemic population growth rates,
and we’d expect to see dark bubbles emerging inside galaxies and slowly expanding outwards,
as system after system was colonized, and its sun slowly darkened as more of its power
was put to use by the growing civilization around it.
This would eventually eat up an entire galaxy – what’s called a Kardashev-3 civilization
– and there’s no reason they have to stop with just one galaxy.
There are some assumptions required for this reasoning, like that a civilization desires
to grow and it’s dependent on matter and energy to do so, and we’ve addressed them
in detail in our episode on the Dyson Dilemma.
That was actually our first episode on the channel, so I recommend watching the remade
version of it rather than the original.
It’s a fairly central concept to a lot of our discussions on the channel, so it’s
no surprise that folks will often think vast expanding bubble of darkness and look at the
Voids – which are vast expanding bubbles of darkness – and wonder if the solution
is just that simple.
Maybe those voids aren’t empty expanses, but rather the mostly densely populated regions
of the Universe; Giant empires far larger than even a Kardashev-3 civilization, sprawling
over many thousands of galaxies.
It’s a very attractive notion on first glance, and we’ll get to the flaws in a moment,
but what tipped me into finally doing an episode on the matter was that’s there something
in the basic concept itself that deserves a second look.
Or rather, that the empty places in the galaxy deserve a first look.
The Universe may be huge and contain billions of galaxies each hosting billions of stars,
but if you point a telescope in any random direction, you usually won’t be aimed directly
at a star.
Trace a straight line out from Earth in a random direction, and you’d get to the edge
of the observable Universe before it passed through a star most of the time, because there’s
an awful lot of nothing, and space is absurdly big.
Knowing this to be the case, we understandably focus our search for life near stars, since
it’s a lot of space to search and anything you can do to narrow it down helps.
Yet, there’s actually an awful lot of something in these places, and we’ve talked before
about colonizing things like our Oort Cloud, so maybe we should be considering searching
them as well.
More on that in a bit, but first let’s talk voids.
As I said, these are expanding empty blobs of dark space, and that’s exactly what we
would expect under the Dyson Dilemma.
However, that’s not quite right.
First, they are not completely empty.
Just as the space between galaxies is quite sparse but still contains many stars, the
voids do include a fair number of galaxies and generally have a mass density of about
10% of what we’d consider the Universal norm.
It’d be weird to assume species expanding into those areas would opt to arbitrarily
bypass entire galaxies, particularly considering we see this everywhere in the Universe.
We would also need to assume such voids were the product of many different emerging civilizations
who’d not share the same reasons for bypassing galaxies.
So too, we see their gravitational effect on nearby galaxies outside the voids, but
there’s no indication there’s a ton of secret mass concealed inside Dyson Swarms.
The other part of that is that Dyson Swarms don’t actually conceal stars, they only
change the frequency of light they emit.
You build one to tap its energy, but that eventually gets emitted as waste heat, and
if it didn’t, everyone inside would be rapidly incinerated.
That waste heat would be emitted as infrared light, corresponding to somewhere around room
temperature or colder.
Folks tend to view a Dyson Swarm as akin to a dam on a river, where the sunlight is the
water, but it’s more like a waterwheel, where the water does its job and then continues
on.
In this case, it comes in as visible sunlight and is transmuted into infrared, invisible
to our eyes but easily seen by our telescopes, and actively searched for by scientists in
the field of Dysonian SETI.
Of course, even a dam only holds water to a point, and for the same reason, once it
hits maximum capacity it overflows or bursts the dam.
I’ll put one caveat on that though.
We often figure there’s a chance a civilization exploiting a galaxy isn’t actively using
most of it, but rather storing a lot of it for long term use to survive the black hole
era after the stars all burn out.
And indeed we have discussed how you could go about disassembling stars to harvest them
for matter through Starlifting, as well as creating artificial black holes to use as
ultra-long lasting and hyper-efficient batteries.
That’s not really producing much waste heat and you do have a strong motivation in a post-biological
civilization to try to minimize power use and keep your territory very cold, as it lets
you do vastly more efficient computation, which is the life-blood of such digital empires.
See the Civilizations at the End of Time series for details.
Folks often wonder if they might just have a way to avoid producing waste heat, and of
course we can never rule out that some civilization might figure out a way to break the Laws of
Thermodynamics.
However, in this case, that doesn’t help.
You build these huge stellar engines because you need their vast amounts of matter and
energy: if your civilization can break the laws of thermodynamics, you have no motivation
to build a Dyson Swarm, because you don’t need that matter and energy.
You literally have perpetual motion machines and free lunches.
You’d also still be detectable by the gravity this region would exert on its more visible
neighbors.
You can't hide that either, if you learn to block gravity somehow, anymore than you can
hide Earth’s early radio transmissions, the evidence of that gravity’s existence
will be plain to see in its past effects from before you learned to conceal it somehow.
The next big one is time.
In our discussions of the Fermi Paradox we developed a concept called TEA, the Time Elapse
Argument, which basically argues that any puzzling phenomena we think might be artificial
and which we see lots of examples from all across the Universe, should be more common
the closer to us that we look.
Astronomy is history: if you’re looking at something a billion light years away you
are seeing it as it was a billion years ago.
Alternatively, anything artificial that’s all over the Universe is presumably something
a lot of civilizations opt to build and we should see more of them as the Universe ages
and those civilizations have more time to build them and more of them arise to build
them.
Quasars, for instance, were more common in the past: we see a higher density of them
the further off we look, so they’re not likely to be artificial in origin.
Similarly, anything we see really far away probably can’t be artificial simply because
the Universe would be so young there, as we see it today.
If you see something 10 billion light years away, in terms of the light’s age, it would
be from when the Universe was younger than the Earth is now, and thus not likely to be
the product of some vast super-civilization.
Now I did say the Voids were expanding, which argues a similar notion.
Something getting bigger as time goes on hits the basic profile for it being artificial,
however the problem is the whole Universe is expanding and the voids match that rate,
and furthermore we can see them emerging as far back as we can look in time, which is
so early that nothing could have possibly evolved yet, even ignoring that the Universe
was a hot and dense place entirely hostile to life at that point.
Though it’s possible a little later than that, in what sometimes gets called the Bathwater
period, life might have evolved, something we’ll address in the upcoming Fermi Paradox
episode on Panspermia.
Indeed that episode is part of the reason that this one is being done as a bonus episode,
since I didn’t want to displace other topics from our schedule with too heavy a focus on
the Fermi Paradox.
It’s also being done because that’s more or less the end of the arguments, making for
a short episode by this channel’s standards.
Voids aren’t hidden K3 civilizations, because we don’t see their waste heat, and according
to known physics, that can’t be possible.
Voids aren’t hidden K3 civilizations because we don’t see their hidden galaxies exerting
any gravitational telltales on regions bordering those voids.
Voids aren’t hidden K3 civilizations because they aren’t devoid of galaxies, just low
on them.
They’ve been explained as a natural phenomena, simply the result of the universe not being
quite evenly distributed when it began and the matter clumping up under the influence
of gravity.
We’re still debating and theorizing about why the Universe was anisotropic – not evenly
distributed – when it began, but we know it was, and whatever caused that predated
any intelligence in this Universe.
At least which originated in this Universe, and we can’t casually rule out that various
civilizations might be immigrants from some earlier or parallel Universe, but that wouldn’t
fit with them living in the voids either.
They’re not vacuuming mass out to their universe in some extreme example of cosmic
mining: the expansion of the voids is just an expansion of space and the decreasing density
of the matter in them, not the raw quantity of matter in them.
Things are spreading out, not disappearing.
As to the bigger voids, we believe them just to be mergers of previous smaller voids, which
happens with galaxies too.
Our own galaxy has cannibalized dozens of smaller ones, and indeed many of stars we
may one day colonize in the Milky Way might not have originated in this galaxy, or may
have been formed by nebula shocked into star production by such mergers, and many of those
extra-galactic stars I mentioned earlier and have discussed using as waypoints between
galaxies in other episodes might have formed here and been ejected by those galactic mergers
as well.
But a final thought on the matter: in a more general sense, just as superclusters of galaxies
don’t contain all our mass, with much in the voids, and just as galaxies don’t contain
all our stars with many in the intergalactic void, there is an awful lot of space between
the stars in the interstellar voids, and that isn’t devoid of mass either.
People often debate the notion of Kardashev-2 civilizations and Dyson Swarms being inevitable
because you don’t need stars for energy if you have controlled fusion reactors or
something better, like feedable kugelblitz black holes.
This isn’t an exemption to the Dyson Dilemma, because we have a pair of assumptions in the
concept that Thermodynamics still applies and faster than light travel is not possible.
So you’d still harvest stars for their matter, for fuel and building supplies, and you’d
also still clump together because you want minimum signal lag time and travel time between
everyone.
This produces the same net effect, big globes glowing in the infrared spectrum, same as
a Dyson Swarm.
However, this does have one weakness, in that it assumes that you have a signal lag time
and care about it.
We can’t be sure no one is ever going to find a loophole around the speed of light,
and communication, just sending info and data rather than mass, would probably be the easiest
such loophole to use.
In a post-biological civilization that’s all you really need, and as we mentioned earlier,
cold is your friend if you’re a digital empire, it makes all your power generation
more efficient and makes all your computation more efficient too.
In such a case, you don’t want to be clumped up anymore, you want to be as spread out as
you can be to be as cold as you can be.
In which case, all those interstellar voids look very attractive as places to live, those
intergalactic voids even better, and those supervoids best yet, and it would be very
hard to spot such civilizations.
Even without FTL communication, they might not care about lag time to their neighbors
if it’s buying them vastly more efficient processing, which essentially means a bigger
population in this context anyway.
If you recall the episodes where we’ve discussed such civilizations, like Matrioshka Brains,
you’d already be talking about running whole modern civilizations of billions on a trickle
of power so they’d hardly need to worry about getting lonely because their neighbor
civilizations were far away.
Or they could be huddled around a black hole in the void, isolating themselves from the
larger universe, as we discussed in our “Civilizations at the End of Time: Black Hole Farming”
episode.
If this is a practical and successful strategy for a long-term civilization, why wait until
the universe is dying to do it?
So this concept is not without its flaws, you’d still expect them to disassemble stars
for raw materials for instance, but it does leave the door open to the idea that maybe
we’re looking for signals in the wrong places, that maybe we should take a peak not at the
stars, but the vast voids between them.
Until next time, thanks for watching, and have a great week!