Could it be that the reason we haven't seen or heard from any advanced civilizations is that interstellar settlement only happens in small clusters? This is the essence of the Percolation Hypothesis.
Host | Matthew S Williams
On ITSPmagazine 👉 https://itspmagazine.com/itspmagazine-podcast-radio-hosts/matthew-s-williams
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Episode Notes
Could it be that the reason we haven't seen or heard from any advanced civilizations is that interstellar settlement only happens in small clusters? This is the essence of the Percolation Hypothesis. Essentially, the challenges imposed by a Relativistic Universe and alien biology could prevent a "Galactic Empire" from ever emerging.
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Resources
Beyond “Fermi’s Paradox” XV: What is the Percolation Hypothesis?: https://www.universetoday.com/148088/beyond-fermis-paradox-xv-what-is-the-percolation-theory-hypothesis/
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For more podcast Stories from Space with Matthew S Williams, visit: https://itspmagazine.com/stories-from-space-podcast
Where is Everybody? The Percolation Hypothesis | Stories From Space Podcast With Matthew S Williams
Episde 78 - Percolation Hypothesis
[00:00:00] The authors acknowledge that this podcast was recorded on the
traditional unceded lands of the Lekwungen peoples. Good morning and
welcome back to Stories from Space. I'm your host Matt Williams and today
we're going to be picking up where we left off with the Fermi Paradox. Which
asks the question, given the age of the universe, the sheer vastness of the
universe, and the fact that the ingredients for life are distributed everywhere we
look in abundance, statistically we have to assume that life is plentiful out there.
And yet, we have found no evidence of extraterrestrial civilizations, yet, nor
have we made contact with them or heard from them. In short, where is
everybody? This question has spawned many proposed answers and resolutions,
and in previous episodes we looked at some of the more popular and
conventional and even some of the more outlandish ideas that have been
suggested over time, [00:01:00] among them the possibility that extraterrestrial
intelligence doesn't exist beyond Earth, or that it is simply rare, that it has a hard
time traveling from one system to the next and leaving its mark.
That it is periodically wiped out by some ancient species that doesn't like
competition or possibly derelict technology that has run amok since its builders
went extinct. And we've also looked at the idea that planets, rocky planets,
much like Earth, that orbit within the habitable zones of their suns may have too
much water in order to support life, or that there is some kind of prime directive
that prevents advanced civilizations, that could very well be out there right now,
from making contact with us for fear of tampering with our natural, social, and
biological evolution.
Thanks for listening. And the possibility that the universe as we know it is just
one gigantic simulation that was designed to keep [00:02:00] us ignorant and
keep us here restricted to our own rock and to prevent us from knowing what's
really going on out there. And today we're going to look at one that is a personal
favorite of mine and definitely one of the resolutions that I think is among the
most likely to be true.
And it's known as the Percolation Hypothesis, which essentially states that
interstellar travel and settlement, or intergalactic for that matter, that it does not
follow a linear progression or an exponential progression. One does not simply
depart with Settler ships land on the nearest planet, and those in turn produce
other settler ships that go out on and on and on and on, with a gradually
increasing wavefront of expansion.And this is often treated as a foregone conclusion among many astronomers
speculative thinkers, when addressing the idea of the Fermi Paradox and the
growth of [00:03:00] civilizations. Instead, percolation theory tells us that the
wavefront of settler expansion That it is subject to ebbs and flows, that it will
grow outward, recede, grow in places, while in other places it will collapse.
And that gradually over time, various pockets of a civilization will suffer
collapse, and so there is no uniform expansion that we would be able to see and
notice very clearly here on Earth. And there are several parts to this theory, all
of which involve the physical constraints of the universe, things we happen to
know for a fact exist out there, all of which add up to space being hard.
And like many proposed resolutions, this one has roots that go farther back than
the proposal of the formalized theory. A good example being a paper authored
in 1981 by Carl Sagan and William I. Newman, titled Galactic Civilizations,
Population [00:04:00] Dynamics, and Interstellar Diffusion. And in this and
other papers by Sagan and Newman, such as the Solipsist Approach to
Extraterrestrial Intelligence, they essentially argued that signals or probes from
extraterrestrial civilizations may simply not have reached Earth yet, and that has
to do with the fact that To reach out and settle any amount of space in this
galaxy would take a very long time.
And by Sagan and Newman's own estimates, they argued that the time it would
take for any civilization to explore the entire galaxy, let alone set up shop on
any planet it deemed habitable, would be equal to or less than the age of our
galaxy, which is 13. 5 billion years. So this would imply that life has emerged in
the more recent past.
And that our galaxy is in a state of disequilibrium, where it's moving from one
state of being uninhabited to inhabited. And these ideas were met with criticism
[00:05:00] from other scientists who argued that this contradicts the Copernican
principle, which basically states that neither earth nor human life, life itself, is
privileged or unique as we know it.
And that life as we know it, and planets like Earth, are representative of the
norm. But, as I said, the formal theory came later. And it was proposed by noted
aerospace engineering author Jeffrey A. Landis. And in 1993, he published a
paper called The Fermi Paradox, an approach based on percolation theory.
Where he advanced the argument that as a consequence of general relativity, An
exo civilization would only be able to expand so far throughout the galaxy. Andas the title suggests, this is based on percolation theory, which describes how a
network behaves when the various links in the network are removed.
And so, as part of this theory, [00:06:00] when you remove enough of these
links, it will break down into smaller connected clusters, and that this, according
to Landis, is what we call an exo civilization. Maybe the process through which
interstellar migration occurs that there would never be such a thing as a
interstellar or galactic empire, but rather just outposts of civilization created
here or there by an advanced species that began to evolve separately and carry
on their own way.
And another argument he made was that in such a galaxy, there would be no
uniformity of motive among the civilizations, which would include whether or
not to send out settler ships in the first place. As he said, since it is possible,
given a large enough number of extraterrestrial civilizations, one or more would
have certainly undertaken to do so, possibly for motives unknowable to us.
Colonization will take an extremely long time and will be very expensive. It is
quite [00:07:00] reasonable to suppose that not all civilizations will be
interested in making such a large expenditure for a payoff far in the future.
Human society consists of a mixture of cultures which explore and colonize,
sometimes over extremely large distances, and cultures which have no interest
in doing so.
Now, to this, someone like Carl Sagan would definitely disagree. They would
say that exploration is in our blood, it's universal, and looking at human history,
especially the massive migrations that took place starting roughly 2 million
years ago, that is when early humans began to migrate out of Africa, began to
settle into Eurasia, and South and East Asia, and by roughly 200, 000 years ago,
modern Homo sapiens managed to make it all the way across Africa.
Into Europe, the rest of Asia, all the way up to the tip of Siberia, and during an
interglacial period, which began roughly [00:08:00] 50, 000 years ago, humans
completed the settlement of the South Pacific, Australia, and New Zealand and
North America. While humans living in East Asia and Siberia, they crossed the
Bering Land Bridge and completed the settlement of North America all the way
to the southern tip of modern day Chile.
So one could point to this history and say, yes, exploration has always been with
us. It's in our blood. It's in our DNA. But it's important to note that the timing of
these migrations, they played a big role. People were motivated to move from
one place to the next due to shifts in the climate, which led to certain regionsbeing no longer habitable, no longer hospitable enough to support the local
population.
Or in some cases, the migrations were made possible by the fact that glacial
period meant increased lowered sea levels. Which is what allowed humans to
complete their [00:09:00] exploration and settlement of the South Pacific and
Australia, and of course, the migration to the Americas. And in a lot of cases,
migrations were only possible thanks to technological innovations.
For example, the settlement of the Arctic Circle. This was only made possible
thanks to the invention of the sewing needle, which allowed for the creation of
warmer clothing by the stitching together of animal hides, which also provided
for better shelters. Animal skins were used by early humans to create tents and
covers for other structures, be they temporary or long term dwellings, and in
fact this is a practice that still goes on to this day.
Though we have access to synthetic fibers, there are many parts of the world
where the traditional practice is still done. Another invention that allowed for
the migration of humans across Africa was the hand [00:10:00] axe.
Specifically, sharpened stone fastened to a strong stick. This allowed humans to
fell the dense jungles that cover much of central Africa, which had previously
been impassable.
And, of course, there was the domestication of dogs, which allowed for dog
toed sleds. This came in especially handy in regions of the world that were
either mountainous or were very, very cold and still covered in glacial ice. So,
while one could argue that exploration and the desire to seek out new lands and
the curiosity that drives us, that this is something that's always been with us, that
it's in our blood as humans, in our DNA, there are certain caveats and
limitations to it.
Basically, human beings do not migrate from one place to another unless there
is population pressures at home or a lack of [00:11:00] resources at home. And
they certainly can't make the migrations unless they have the requisite
technology to carry all the things that they're going to need with them,
especially where very difficult terrain is concerned, and other natural barriers.
That can include high mountains, the ocean, dense jungles, the list goes on. So
one could see how this would very much apply to space. Keeping in mind that
space is a hostile environment, there are no safe havens where you can easily
put down, especially in interstellar space. Traveling from one end of the solar
system to the next, we've learned that there are plenty of places there whereresources are available, where we can stop to refuel or take on materials that
could be converted into resources.
A process known as in situ resource utilization, and this is why it's such an
integral part of mission planning today. As we continue to [00:12:00] plan to
send missions beyond Low Earth Orbit, to the Moon, to Mars, and other
destinations that are too far to make resupply missions from Earth practical, we
need to be able to take on resources locally.
And this is certainly true of the early human migrations and all migrations to
this very day. But to travel through interstellar space, chances are you need to
bring everything with you. Everything that you're going to need in order to
survive. And on top of that, you've got the challenges imposed by microgravity.
How exactly are you going to get around the physiological effects of traveling
through deep space and interstellar space? Which can be quite severe the longer
you're out there. And on top of that, you're also concerned about cosmic rays
and other sources of radiation, which could become problematic before long,
even with radiation shielding.
There are still risks, and [00:13:00] there's no guaranteed strategy for addressing
them over the long haul. And when it comes to interstellar travel, we're talking
between decades or even millennia. Which of course is a consequence of living
in a relativistic universe. In any case, if this is starting to sound a bit like the
Aurora Hypothesis, well, there's a good reason for that.
In this paper, Professor Adam Frank and his colleagues, they argued that the
settlement of the galaxy would occur in clusters, because not all potentially
habitable planets would be hospitable. So yet another challenge on top of space
radiation, microgravity, and relativity. Suddenly, the idea of a uniform,
expanding settlement front seems kind of ridiculous.
Another similar argument was made by astrophysicist Milan M. Sierkiewicz,
who wrote the 2008 study Against the Empire. And in this paper, he used two
[00:14:00] models to simulate the behaviors of an extraterrestrial civilization.
And whereas some were driven by the desire for expansion, others opted for the
optimization approach.
And this is what he called the Empire State and the City State models. And
based on his analysis, he argued that an advanced species would prefer to
optimize the space it's already occupying rather than attempting to spreadoutwards and settle other star systems, which would offer very little in the way
of payback or benefits, not for a very long time at least.
And this, of course, is touching on the Trans Hypothesis proposed in 2002 by
John M Smart, the CEO of the Foresight University, and the founder of the
Acceleration Studies Foundation, basically looking at arguments made by John
Von Newman and John d Barrow. Richard Feynman and Eric [00:15:00]
Drexler, all theorists who explore the idea of self replicating technology and
nanotechnology and how these would impact our society in drastic ways that we
can't even possibly imagine yet.
And, of course, how a more advanced civilization will have already
accomplished that and chosen to forgo the physical universe or meat space for
an optimized existence in far, far, far smaller scales of matter. Now, as I said,
this is one of my favorite proposed resolutions. Because it does seem so
plausible.
It takes into account humanity's own history of migrations, but also humanity's
history of exploring space, and how the realities of venturing beyond one's
home planet are going to be so much more challenging than any other type of
migration that has ever occurred, from our perspective. What's more, it comes
down to scientific principles that have been [00:16:00] demonstrated backwards
and forwards, so there is no need to assume further advances in technology,
such as the development of FTL travel or communications.
But above all, there is the argument that the very idea of there being vast
interstellar empires that span entire galaxies, that this is simply ridiculous. And
this is perhaps the greatest weakness of the Hart Tipler conjecture. It assumes
that a civilization would be able to easily spread from one corner of the galaxy
to the other, even if they were limited to 10 percent the speed of light.
And their estimates varied, but Hart himself produced very, very questionable
estimates, saying that it could be done in 650, 000 years. That was based on
some extremely huge assumptions and very simple math. Now, Tipler was a lot
more nuanced and realistic in his approach. He [00:17:00] believed that the
same process could be done in 300 million years.
But here, too, to not consider the challenges and constraints imposed upon
interstellar expansion, How this could lead to all kinds of delays, how not all
planets would be habitable or receiving to foreign life forms, and to not even
consider how difficult it would be to maintain communications in this empire,
or trade, Or how the civilization itself, the central civilization, would becompletely helpless in the face of a crisis in any of its peripheral settlements,
any other planets within its empire there, or engaged in an uprising.
They would be absolutely powerless to stop it because sending ships there
would take far too long to be able to do anything about it. And this is
reminiscent of the Dark Forest Hypothesis. In the centuries [00:18:00] or
millennia it would take to get to even the closest star systems, the local
civilization would have advanced considerably, while the fleet and transit
wouldn't have advanced at all.
So, yes, this theory does embrace that notion there, that galactic empires, the
very idea that they would exist, or to accept such an idea as a foregone
conclusion, is inherently naive, There really is no other way to put it. Of course,
that being said, Landis model also has some inherent assumptions, which he
acknowledged ahead of time.
Among them, there's the assumption that interstellar travel would impose strict
limits on how far civilization would be willing to go, That they would be
content to remain within communications range and realistic travel range of
their home planet, and that any settlement beyond that would be undertaken by
offshoot of their civilization quite some [00:19:00] time later.
So this certainly has an internal logic to it, but it does rule out the possibility
that humanity or any other civilization would never achieve the kind of
breakthroughs necessary to have faster than light communications or faster than
light travel. And there is a theoretical basis for both, so we can't just assume that
this will never happen for anyone.
As Freeman Dyson and as a sort of Unspoken rule of SETI, it's understood that
if we can fathom something and prove that the physics are sound, then chances
are somebody else has already built it. So FTL remains a big unknown, both
communications and travel. And there is some speculation that whereas
quantum entanglements could allow for the transfer of information, so FTL
communications over interstellar distance, [00:20:00] that FTL travel could not.
So this would still mean there'd be limits to how far civilization could expand,
but that it would also be able to maintain tighter control or tighter cohesion
among its settlements that would be in a cluster, a local cluster of space. And it
further assumes that once planets are settled, that the process of course would
take a very long time.So there would naturally be cultural evolution that would create a divergence
that the very act of settling other star systems would lead to the rise of new
offshoots. People that have their own distinct culture and identity that would not
want to be part of the parent civilization anymore, or part of a concert of worlds,
if you will.
And there's the fact that historical allegories, a lot of them, are at play here.
They're just woven into the fabric of this. The history of [00:21:00] human
migrations, the history of colonization, the independence wars that inevitably
followed. So this is, once again, a case of speculation by projection, where we
assume what's likely to motivate an extraterrestrial intelligence or an advanced
civilization, based solely on ourselves as an example.
But, as I said, all of this does have a coherent internal logic to it, and I believe
it's the one that makes the most sense. And it certainly would explain why
humanity has not found evidence of any advanced civilizations out there.
There's no such thing as a galactic empire. It's simply not possible based on the
laws of physics as we understand them.
And when it comes to general relativity, we've tested them nine ways from
Sunday, and they still hold up. So It seems like the inherent assumptions are
safe ones, as far as physics are concerned. As for [00:22:00] the rest, there's
really nothing we can do about that. As I've said before, when it comes to any
proposed resolution to the Fermi Paradox, humanity is hampered by the fact that
we know of only one planet in our universe where life exists, and that's here.
We know of only one advanced civilization, that's ourselves, and we're only
really able to speak for one intelligent species. We cannot speak for the motives
of any other creatures that have demonstrated sentience here on Earth. Nor can
we assume what an extraterrestrial intelligence would even be like.
But, of course, that's the best reason to keep looking and to investigate these
proposed resolutions. Until we find evidence of life beyond Earth, beyond our
solar system, we're going to be stuck speculating about the kind of conditions
under which life can emerge and the commonality of it. Right now, we really
have no [00:23:00] idea if life is ubiquitous in the universe or very rare.
And of course, the same goes for intelligence, but with a much greater degree of
uncertainty. So, we really have no choice but to keep looking, and in the
meantime, these hypotheses do provide a means of tailoring our approach. So,
that's the beauty of the percolation hypothesis. It does not rule out the presence
of extraterrestrial intelligence out there in the galaxy.And it also complements several other hypotheses, like the Aurora Hypothesis
and the Transcension Hypothesis. And unlike many other proposed resolutions
to the Fermi Paradox, it doesn't suffer from the, it only takes one fallacy.
Basically, it doesn't involve an assumption about uniformity of behavior or
motives, which invariably will break down if only one civilization chooses to go
in a different direction.
In fact, it embraces [00:24:00] that. It says that there's likely to be diversity of
motivations and behavior. And that is a source of strength in this argument. In
any case, this just about brings us to the end of our ongoing series on the Fermi
Paradox. For the next installment, we will be looking at the SETI Paradox as a
proposed resolution, and this will be the final episode in this particular series.
At least until some new, fangled, interesting proposed resolution comes up,
which probably won't be long. In addition, there will be episodes that explore
concepts like the Circumstellar Habitable Zone. What is it? How do we define
it? What are the basic parameters, and why are they changing? We'll also look
at the life and times of Freeman Dyson, the famed inventor of the Dyson Sphere
and Dyson Structure concept.[00:25:00]
We'll also be looking at more indigenous astronomy by taking a look at the
Aztecs, the Maya, the Incans, the Anishinaabe, and Ojibwe, and the
Hul'q'umi'num and Inchalnith of the west coast of Canada. In the meantime,
thank you for listening. I'm Matt Williams, and this has been Stories from
Space.