It is common to ask what wonders we might
find while exploring space, what new civilizations we might encounter, but what would the galaxy
be like once we explore and colonize it, if we never meet anyone else out there? So today our topic is the future of the galaxy
if humanity truly is the first technological civilization to arise in it, something we
touched on briefly last year in our Episode on Uplifting. That was a two-part collaboration episode
with John Michael Godier, and while with two episodes we got to spend more time on the
topic, both John and I felt that there were a lot of implications about the future of
the galaxy that we brushed against but need more exploration. We can contemplate exploring space and settling
the galaxy and what the solution to the Fermi Paradox will be, if we will meet anyone out
there, but often what comes after gets skipped. What is the galaxy like after you’ve explored
and settled it? What challenges does a galactic wide civilization
face and can you even have such a thing? This is what John and I will be trying to
tackle today. To do that, we must first discuss the Fermi
Paradox. Of course the Fermi Paradox is a familiar
topic for regulars of either of our channels but discussion tends to focus mostly on reasons
why alien civilizations aren’t being seen by us. The core of the Fermi Paradox is that it simply
seems peculiar that a Universe as old and gigantic as ours could be absent of other
intelligent life, it seems paradoxical. Many solutions have been proposed for handling
this but most focus on why these civilizations emerge often enough but can’t be seen by
us, either because they are hard to see or have ceased to exist. We spend a lot of time discussing these proposed
solutions, and their merits and flaws, but the alternative, that we are the first civilization
to emerge in our region of the Universe, is going to be our focus for today. Not so much the reasoning behind that solution,
but what its consequences might be. What a galaxy might look like down the road
if humanity was the first civilization to emerge and went out and colonized the whole
place and perhaps beyond. Particularly the notion that we might encounter
other alien civilizations that just happened to emerge during that colonization period. As improbable as that would seem if no one
else had in the billions of years before that, this scenario is actually quite likely, for
a given definition of the term ‘alien’. From the perspective of the Fermi Paradox,
this sort of scenario is possible under what is generally known as the Rare Earth Hypothesis. The basic notion being that while there are
billions of galaxies each host to billions of stars, resulting in billions of billions
of planets, the conditions for life to emerge on those is quite rare. This is usually broken down into the idea
that life emerging might be ultra rare, that the evolutionary path to intelligence and
technology might be ultra-rare, or that such civilizations surviving to colonize the Universe,
and choosing to do so, is ultra-rare. None of these are exclusive. For instance, it could be life emerging happens
on maybe only one in a million planets, leaving millions of planets in our galaxy alone which
are inhabited or were at some point. Yet of those, perhaps the evolutionary pathway
to high intelligence is so uncommon that only one in a million planets have achieved that
thus far. It may never occur, as their Sun may die or
strip off their oceans or atmosphere before that happens, or it may be that they just
need more time. The Universe might seem old, at nearly 14
billion years, but in truth it is barely into the stellar era, and stars will be regularly
forming for at least a trillion more years and the heavier atoms needed for rocky planets
and biochemistry will continue to grow more common as time goes on. If only one in a million planets has ever
hosted life, and only one in a million saw it reach higher intelligence, than those two
combined would make it improbable any other civilization besides our own has yet arisen
in this galaxy. These barriers to life forming and reaching
intelligence are collectively referred to as filters, and we will often refer to Great
Filters, a given filter that is particularly improbable, lottery odds. One of those that had been suggested is that
even if intelligence develops fairly often, this does not necessarily lead to abstract
thinking and conceptualizing, let alone serious technology. After all, there are many species on Earth
that have fairly large brains and had them as long as various hominids have, but not
done much with them. Even of the hominids, humanity and it’s
nominally extinct near human cousins or predecessors like Neanderthal and Homo Erectus, sat around
with brains fairly parallel to our own for many thousands of years without doing much
technologically. We’ve had fire for around a million years,
but using fire for pottery and metalworking are quite recent, and it is entirely possible
that many civilizations never go down the higher-technology pathway, rather than it
being inevitable, as we often think of it. Indeed we have plenty of historical examples,
all of which come from long after civilization had already embraced a lot of technology and
innovation, like Ancient Rome, where new technologies were simply not used, even though they knew
its benefits and in no way doubted that technology's effectiveness. Quite to the contrary they often felt using
it would ultimately hurt them more than it helped. Those of us living nowadays know all too well
the advantages of technology but also its perils, and unlike our ancestors, we don’t
particularly have to worry about dying early of sickness, starvation, or other hardships
if we decline to embrace a new one, like artificial intelligence, so if many civilizations declined
to use beneficial technology even while having to endure those hardships, it may be plausible
that some opt to avoid one technology, or even all further progress, out of fear of
the consequences of using it, reasoning things are good enough as is. That fear represents one of our two remaining
filters of the Fermi Paradox humanity hasn’t hit yet, that we might destroy ourselves long
before colonizing other solar systems. The other one is that colonizing other systems
might turn out to be impossible, impractical, or undesirable for some reason. All of these filters add into the general
Rare Earth Hypothesis for the Fermi Paradox, that the galaxy seems to be an empty place
not because we can’t see other civilizations, but because there simply are not any, or the
handful that exist stuck on their homeworld or near enough that they haven’t left an
obvious footprint for us to detect yet. This scenario is our main focus for today,
as we ask what the future will be like if it is the right solution and those last two
filters, self-destruction or not colonizing the galaxy, are ones we overcome. In this regard we will also be examining why
so many of the other solutions to the Fermi Paradox just don’t seem to work, if such
civilizations are indeed common. As best as we can tell, we are not too likely
to find colonizing other planets in our solar system an insurmountable barrier or one that
folks decline to do. If you can do that, then you have the option
of making generational arkships to colonize other systems, even if you don’t get far
superior drives which might let you get ships up to near light speed or maybe even somehow
surpass it with warp drive or wormholes or other faster than light, FTL, methods. It would also seem improbable any natural
disaster could destroy your civilization at this point. As to unnatural disasters, like artificial
intelligence or humanity being replaced by cyborgs or genetically engineered super-humans,
realistically this doesn’t much matter to the Fermi Paradox since you are usually just
replacing one aggressive and advanced species with another that’s more aggressive and
advanced, and thus even better at colonizing the galaxy. Of course you might have an AI that was non-expansionist,
just taking over Earth, but if you have already colonized your solar system that won’t wipe
you out and you can just expand into the galaxy while it sits on Earth doing whatever amuses
it. If we’re assuming this galaxy is devoid
of life, than we have the whole place to ourselves, and while those planets aren’t naturally
hospitable to life there should be billions that are much easier to terraform than Mars
or Venus. Alternatively, if the galaxy isn’t devoid
of life, just technological civilizations, we have to decide what to do with those inhabited
planets. In some ways, what we think we would like
to do informs of us what aliens might do, and it’s one of our approaches to the Fermi
Paradox. If it makes sense to us to do something, it
might be likely aliens or future humanity would act that way too. Of course, there are limits on that, an alien
mind is likely to demonstrate alien behavior, and it is worth remembering that while we,
nowadays, can’t wait to explore the cosmos to meet new civilizations and learn about
them, quite a few of our ancestors would not have shared that desire entirely. Like us they were curious, a trait we’d
expect any technological civilization to share, but they might have wanted to encounter new
civilizations so they could take their planets and sacrifice them all to the Sun God in thanks. In our last collaboration we discussed the
concept of Uplifting, which is where you take something like a dolphin or chimpanzee and
modify it to be smarter and able to handle technology. In those episodes we defined three types of
uplifting, technological, physiological, and mental, none of which are exclusive either. You could encounter a species with all they
need for technology except that technology, like early homo sapiens, and technologically
uplift them. For something like chimpanzees you’d also
need to mentally uplift, enhance their brains a bit. For something like dolphins you'd need to
physiologically uplift them too, giving them hands or digits on their fins to handle objects. One might opt to do all of the above or even
just one, like giving chimpanzees bigger brains but not technology, to see if they got it
on their own. This is one way in which we could encounter
alien civilizations, by making them, and indeed you might send out sophisticated probes in
advance of colonization waves to do just that. We often discuss how you might colonize the
galaxy by sending out automated probes to do the initial work and it seems common-sense
to include an ability to detect inhabited planets so you don’t end up accidentally
terraforming a planet some other critters already live on. Potentially such a probe might have orders
to engage in uplifting instead, where it encounters something which might make a good candidate. As to why you might do that, we’ve also
discussed the difficulties in quarantining a planet in the long term. Here’s the problem, as we expand outward,
possibly encountering inhabited but non-technological planets, we will obviously be curious about
them. We also might decide we need to seal them
off so nobody can exploit or tamper with them, but in the long term that’s a very hard
policy to maintain. Realistically, probably an impossible one,
as you'd be looking at maintaining a quarantine for potentially many millions of years before
any civilizations might arise. That is very long time to try to maintain
anything unchanging, and it would only take one lapse for someone to sneak in past that
quarantine and break it. We discussed the near impossibility of maintaining
such a long term quarantine in more detail in the Alien Civilizations series episode
“Smug Aliens”. So you might decide that the path of doing
the least harm would be to just tell your probes to uplift anyone they encounter who
is over whatever threshold you deem right, and to go ahead and terraform any planet that
is just basic microbes, grabbing samples for study later. They could be a threat to you but if your
probes aren’t all that far ahead of your colonization waves, it’s very unlikely,
even if they’re given all your technology that they’d be some sprawling interstellar
empire who could knock you over. You had a big headstart after all, you’re
already out colonizing worlds and your probe at most only carries the most recent technological
updates it got from home, which if it’s a few thousand light years away, is now as
far out of date technologically as our ancestors a few thousand years ago who thought Bronze
was the best stuff ever. Even if they’re not grateful for the boost
up, any uplifted civilization we spawn would presumably be rather intimidated by their
creator species, who they know already had a million colonized systems when the probe
arrived, and whose awesome technology is probably considered antique junk by it’s makers. However, one hardly has to encounter aliens
to do uplifting, and this is where we start needing to talk about how ‘humanity’ is
a fairly ambiguous term in regard to a future galactic civilization. Even if Earth is where that all starts from,
which is arguably still the case if some of those lifeforms had originated on alien planets
and been uplifted, they’re essentially the adopted Children of Earth. Human, or person, or citizen, are all rather
hazy concepts when you start going outside a modern context. Whose more human, an alien raised on Earth
who went to school here, eats our cuisine, coaches a baseball team, and watches our films
and TV, or a human raised on it’s native planet, with its customs and traditions? We could handwave that away by pointing to
something like DNA, but a cyborg, or a human mind uploaded into an android or just a virtual
world, has no DNA. What’s more, as we go out and colonize space,
even if folks weren’t very pro-actively using genetic engineering or transhumanist
pathways, which they likely will, we’d diverge a lot from each other. Same as a species cut in half when a land
bridge melts between two lands, living on alien worlds scattered around the galaxy is
going to result in a lot of divergence. All the more so since those are alien worlds,
aliens suns, alien geology and weather and day length and so on. Such processes take thousands of generations,
but then so too does colonizing a galaxy at sub-light speeds. And again, that’s under normal conditions,
you start playing around with genetics and cybernetics and uplifting, especially if you’re
trying to adapt people to live in alien environments, and your timeline gets expedited. You could be a ship’s captain who dropped
some colonists off somewhere, and come back to that planet a thousands year later expecting
the colonists to have mutated a bit. You’re expecting them to show some characteristics
that would represent a new ethnicity, maybe with some unique phenotypes like purple hair
or orange eyes, but instead find people walking around on six-legs who insist they are human. Considering our hypothetical captain is a
thousand years old, implying life extension technology, someone might come out to greet
us from the original colonists, still looking fairly human perhaps, and shooing off their
six-legged great-grandchildren. Indeed, things are just as likely to be changed
back on Earth, if not more so. Colonies might be loaded up with adventurous
mindsets but they’d still only possess a small fraction of Earth’s diversity and
technological might. You get back to Earth and send a report to
the Secretary General about how disturbed you are at the six-legged humans, and he might
reply back with a note sharing your concerns and asking to meet to discuss it in person. You go see him and are rather taken aback
to see a dolphin, and when you let your surprise slip, he reacts angrily and demands to know
what you have against Europans. Uplifted Dolphin-cyborgs having been around
Earth and the various icy moons of our solar system so long it doesn’t even occur to
him you’re a species-ist, so he just assumes you’re angry about someone whose family
migrated from Jupiter’s Moon Europa being the Secretary-General of Earth. If you headed off to Orion Nebula, a mere
1300 or so light years away - practically in our backyard in galactic terms - you might
meet humans who looked entirely human, but had assimilated into the culture of the Orions,
once racoon like creatures they’d uplifted and who modified themselves to human form,
but kept their basic culture and brain architecture, and who hated modern Earther’s as physiologically
impure. Ten thousand years ago they were animals running
around forests, and 8000 years ago they were smart racoons learning technology from their
human friends, and decided to tinker with themselves to look more humanoid, and became
so obsessed with that body-type as a sign of civilization that they eventually became
entirely human in appearance, and are disgusted by any who isn’t. Off on some other world, people didn’t uplift
dolphins or chimpanzees, they modified themselves into them, and just kept the brains. They revere the animal form but wanted to
keep the intelligence. Or maybe they meant to but that decayed, and
now the Orions come by, see chimp-like like primitives already somewhat humanoid, figure
this is some planet that got quarantined rather than uplifted, and uplift them steadily into
more human mind and form and teach them to loathe the non-humanoid, exactly opposite
their ancestors beliefs. And again, it doesn't matter if we encounter
primitive alien life or not, things like this can just happen by the sheer weight of time
and distance to diverge, indeed even that distance might not matter much, you could
easily see a far wider spectrum of divergence just inside a single solar system as time
marches on. Time, in terms of the astronomical scale,
is always hard to put in perspective. This is probably why so many sci-fi settings
take place a few centuries to a few millenia ahead in time. But imagine for the moment that humanity sets
off its first wave of colony ships in the year 2500, and that those move outward in
an expanding sphere at about 10% of light speed. When you’re going that slow, you don’t
bypass any system that is reasonably hospitable in search of close parallels to our own. So by the year 3000 you’ve settled everything
within 50 light years. A speck so small it wouldn’t even appear
as a single pixel on a galactic map. And yet, there are about 2000 stars in this
volume, enough to make an empire already dwarfing most interstellar empires we see in fiction,
and that’s assuming they are only doing planets, not the various space habitats we’d
expect as precursors to Dyson Swarms and Kardashev 2 Civilizations. By 3500 AD, they are out to 100 light years,
and something like 16,000 stars. By 4000 AD, they are 150 light years out,
a sphere now just big enough to be a pixel or two on a galactic map, and containing over
50,000 stars. They are now as far ahead from us as we were
to the Early Roman Empire, and likely a lot more diverged from us and each other, likely
a lot more different than modern Italy is from Spain or England, both prior colonies
of Rome. Even the nearest of those stars is suffering
far more communication and travel lag than any of those three countries ever had from
each other. Most people, incidentally, probably still
live back around our original star at this point, for all that they have 50,000 other
stars to call home. It is far easier to build artificial habitats
around your own star than colonize worlds around others, and by now, even assuming they
still stick to something recognizably human-ish in appearance and manner, they could easily
house 10 quadrillion people, simply by having the population double every century, and they’d
still be nothing approaching a genuine Kardashev 2 civilization, which could easily house a
thousand times that population. That’s hardly fast growth either. Humanity quadrupled in the 20th century after
all, hitting 6 billion right before the end of the millenia, it is 27% higher 18 years
later, at 7.6 billion in 2018. But by the year 5000 AD, they might have reached
that full Kardashev-2 status back around Earth and our solar system, 10 million, trillion
people, while off in the leading edge of colonization they’d have reached 250 lights year out. Still a tiny dot on the galactic map, but
one containing a quarter of a million stars. But back near Earth, things are already massively diverging. A trillion massive habitats, each effectively
it’s own large island in space, is fertile ground for divergence of every aspect of mind
and body. Even if things are peaceful and moving slowly,
you’d expect to see thousands of those habitats where folks had focused on marine life, possibly
had gills added, be it cybernetic or genetic. Others where they’d modified themselves
to low or no gravity, and live in giant bubble of air with floating homes and ecology adapted
to drift around the endless sky. One who’d sneered at biology in favor of
pure cybernetic existence, or abandoned the physical entirely to live inside entire moons
converted into computers, whose interior virtual landscape is so immense it would dwarf even
a classic Dyson Sphere. They might be a small minority of civilization
at this time, but each of those factions outnumbers humanity of the twenty-first century by an
order of magnitude at least, and indeed all the colonies combined, who themselves have
precious little in common with each other. Now things change, and the classic image of
sci-fi Space Opera totally shatters. In 5000 AD the solar system is finally maxed
out in population, and the earliest colonies are probably filling up the original worlds. Even now, every single colony, a quarter of
a million systems, contains not even a single percent of humanity even if they’d been
breeding at a ferocious rate. This is still the early days of colonization,
we’re not even 1% done with the timeline for colonizing the galaxy, and have not even
1% of people living outside our native solar system, and yet already we see an inevitable
divergence, with countless factions back around our Sun waiting to branch out even further,
and a quarter of a million sapling civilizations beginning to grow and branch out themselves. To envelope their own sun and to spread to
new ones, even as in all likelihood vast armadas of colony ships launched from way back at
Earth continue to head out further. You are still nothing like a galactic civilization,
and you already face so much time lag and divergence that any concept like a unified
civilization is nigh impossible. And yet we’ve only begun to explore the
scenarios and challenges for a galaxy-spanning humanity. John and I will continue that in Part 2 over
on his channel. Trying to wrap your mind around just how big
the Galaxy is, let alone the Universe, is very difficult, and I think it’s what damages
a lot of science fiction that tries to paint a portrait of interstellar civilizations and
our galaxy. They’re not absorbing the sheer scale of
things and the implications of what it would mean to civilizations. If you’d like to get a better grasp on the
sheer scope of Galaxy and the Universe beyond, then I’d recommend the course “Sizing
the Universe” over at Brilliant.org. That will walk you through both the history
of attempts to do it, and our various methods for estimating size and distance nowadays,
and will give you a much more intuitive feel for the scope of Interstellar space, and why
so many first glances at interstellar civilizations in fiction don’t hold up well when taking
into account those enormous quantities of stars spread over vast amounts space and time. Any would-be space colonist is going to have
adjust their thinking to appreciate that enormity, and if you want to learn how to quickly understand
it yourself, go to brilliant.org/IsaacArthur and sign up for free. And also, the first 200 people that go to
that link will get 20% off the annual Premium subscription. Okay, next week we will be a little closer
to home, as we return to our discussion of Orbital Infrastructure in the Upward Bound
Series to explore the possibilities of transferring power down to Earth via Power Satellites. We were talking about colonizing our region
of the galaxy today in part 1, and how it would require immense numbers of ships, and
we will be looking at those armadas of colony ships two week from now in Exodus Fleet. If you haven't already headed off to watch
part 2, there is a link on the end screen at the end of the video and one below in the
video description. If you enjoyed this episode, please like it
and share it with others, and don’t forget to subscribe to both my channel and John’s,
for alerts about when new episodes come out, and I’ll see you again in just a minute
in Part 2.
