- In the summer of 1950, at the Los Alamos National Laboratory, famed quantum physicist Enrico Fermi was one day
chatting with colleagues about a cartoon published
in the New Yorker that depicted aliens gleefully emerging from a flying saucer. Accounts from his three
colleagues at the time, Konopinski, Teller, and York, slightly differ in the exact wording, but all agree that Fermi asked a question that would become immortalized and went along the lines of, where is everybody? It was this question that gave birth to what is commonly referred
to as the Fermi Paradox. Despite seven decades past, it remains one of the most hotly debated topics in science, and
in the era of looming AI, it has never been more pertinent. Some say it's not a paradox, or that it's not Fermi's. Others say that it's
been dissolved already. There's a lot of dissenting voices, and it can be confusing to keep track of what exactly we're even talking about. So today, let's work through the nuances of the Fermi Paradox. Let's go through its history, why there's actually two versions of it, the role of AI, and at the end of the day, what does it all mean
for our search for life elsewhere in the universe? So let's start with understanding what the Fermi Paradox is actually about. If we come back to its origins, Fermi simply asked, where is everybody? When stated in isolation
and in a modern context, I think it's easy to misinterpret Fermi's original question as
regarding what is often called the eerie silence. The fact that after decades of searching, we haven't detected any
extrasolar artificial radio transmissions. Now, I think when people hear
the phrase Fermi Paradox, this is actually what
they often have in mind. After all, that has been
our primary scientific effort to detect alien
life over the past five or six decades. And indeed, there's been
no Jodie Foster moment of a slam dunk detection. But of course, in 1950,
there had been hardly any serious radio searches yet either. Because remember, this is 10 years prior to Frank Drake's famous
Project Osmo Experiment, which really dawned the
modern radio search era. When we put Fermi's quote back into his context of that New York cartoon, it becomes clear that Fermi's question was concerning visitation. Despite this, discussions of his eponymous paradox
often miss this nuance, and the term has sort
of evolved into a catch all phrase for any and all
null evidence for aliens. Now, at this point, this
distinction might seem a little trivial, almost academic, but as we'll see, it has some important ramifications down the road. Another contentious
point is the name itself. The phrase Fermi Paradox
first appeared in print in 1977 in an article by
physicist David Stevenson, and evidently, it was pretty catchy. It's now one of the
most frequently googled topics in all of science. Of course, Fermi was almost certainly not the first person to
wonder this question. For example, Soviet rocket scientist Tsiolkovsky published
similar thoughts in 1933. Yet more, over the years, many have argued about whether it should really be called a paradox at all. Maybe it's best to call it a problem, or simply a question. Three terms which are of
course not mutually exclusive. Paradox here means logical contradiction, but as many have pointed out, the contradiction only
exists if one accepts certain assumptions. So, for example, in
Fermi's original framing of the problem, the assumption that falls into contradiction is
that which was depicted in the New Yorker magazine, i.e. visiting aliens. If one rejects that assumption though, as indeed Fermi concluded was most likely, then there is no contradiction. Aliens don't visit us because they lack the ability or the will to do so. So does this mean then
that it's a misnomer to call this a paradox? You know, honestly, part of me doesn't really care about this that much. I mean, this is semantics at this point. It's kind of similar to how I feel about the classification of Pluto. But I know that many do care, so perhaps it is best to think of this as a conditional
paradox, a logical contradiction that is conditioned upon a certain set of assumptions. And clearly that still
has utility because it allows us to apply pressure
to set assumptions. So for the rest of the video, whenever you hear me say paradox, think conditional paradox. Okay, with that in mind then, what are the conditional assumptions that are underlying the Fermi paradox that we might be able to
apply pressure to then? Fermi's original version, of course, was visitation. But even here, it's unclear exactly what he defined that to encompass. Does it include alien satellites, lurkers designed to observe us from afar, artifacts on Europa, or is it just limited to the New Yorker scenario
of aliens literally landing their ship in broad daylight in Manhattan and stealing
our garbage cans, which incidentally was a real problem in the 1950s? If it is just the latter, then the conditional assumptions that fall into tension here are of limited utility. Excluding alien spaceship landings represents a rather contrived and narrow corridor of all possible alien
behaviors and activities. It hardly applies much pressure to aliens as a general hypothesis. In contrast, if Fermi
imagined it to extend to lurkers and artifacts, then really there's no paradox
since we haven't applied much observational pressure to those. Alien UFO proponents would probably have a very different view
about what I just said, of course, but the scientific community certainly does not have
access to any credible evidence to that effect so
we'll just leave that aside. So the scope of Fermi's question is poorly defined and open to interpretation, but of course he can be forgiven
for this because after all it was just a casual lunchtime remark. It was never intended to spark 73 years of academic debate. Crucially though, how
one interprets Fermi's original question leads
to a split in the road. We arrive at least two different versions of what are both called the Fermi Paradox. For simplicity, I'm going to call them the direct and indirect versions. Let's start with the
indirect version first, which to me is the less interesting one. I'm going to define the
indirect Fermi Paradox as the following. It's an apparent contradiction that we haven't detected
any evidence for aliens using numerous experiments under the assumption that aliens exist and they occasionally
engage in such activities. That's the conditional part. Okay, so what are the experiments that we're referring to here? Most obviously one might
think of radio searches for artificial transmitters which spans numerous experiments such as those by the SETI Institute
and Breakthrough Listen. After decades of listening,
no one seems to be calling. An eerie silence. Beyond radio there has
been some more limited efforts to search for
optical transmissions, especially brief laser
pulses sent our way. In addition there's also been some efforts to search for weird eclipses of distant stars that could be the signature of alien megastructures, with
Boyajian's star famously stirring up a lot of interest in this some years back. And on that same note there has been some surveys
too for the infrared excesses expected from Dyson spheres, stellar energy harvesting machines hypothesized by Freeman Dyson. That's not an exhaustive list by any means but as you can see it encompasses both intended messaging such
as a laser targeted at us as well as unintended signatures such as a Dyson sphere. We haven't done nearly as
much as we'd like though. The truth is that our searches have been of limited scope and
scale with funding for alien hunting being historically very difficult to find. But looking for life in the universe should not be any more taboo
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nordvpn.com/coolworlds and let me just thank NordVPN one more time for supporting us. Coming back to our alien searches now, after 60 years of trying
should we conclude that we are alone? In short, no. Remember that the indirect Fermi paradox is conditional, one predicated upon the assumption that aliens engage in these activities. But even if we conclude that aliens do not engage in these activities, that does not mean there are no aliens. And it's precisely here that folks, including many scientists, get positively giddy generating countless remedies to this paradox. There are a dizzying number
of solutions out there. In fact there are entire
books now cataloging the hundred plus ideas
that have been proposed. Notable examples include
the zoo hypothesis, akin to Star Trek's prime directive, which posits that we're
being deliberately left alone, maybe studied as
part of an experiment with a strict no interference policy. On the other hand there's really the total opposite idea that we're not smart enough to warrant the
attention of aliens at all. I mean when was the last time you tried to converse with an insect? From an observational
perspective the answer may simply be that we've not
looked long or far enough. After all modern searches are estimated to be analogous to filling a bathtub with ocean water, seeing no fish in it, and concluding that the
ocean must be sterile. Others say that maybe
we've not been listening with the right technology, perhaps they're using neutrinos or gravitational waves or
perhaps something else entirely. And I could go on with another hundred resolutions like this and that's exactly the point and why I consider this a feeble and indirect paradox. There are so many possible explanations as to why we don't see
evidence for alien activity that it hardly excludes the presence of that alien activity
nor indeed the existence of aliens more generally. The great problem with our searches is that a null result doesn't
really rule aliens out. It's effectively impossible to ever falsify the alien hypothesis. On the other hand I have
to say I am a supporter of these efforts because they
could strike gold tomorrow. They could make a positive detection that fundamentally shifts
our whole worldview upside down and if we don't look then of course we're guaranteed to fail. What we need is something firmer, something with fewer logical escape routes and that's where many
turn to what I will call the direct Fermi paradox. The direct version comes
back to Fermi's original question in its defining context. Why don't we see aliens here on earth? Now as I pointed out
earlier that's a little vague stated as such so the direct paradox is improved by focusing on colonization. I'm calling this a direct paradox because whilst we can't
be sure whether aliens are messaging us right now
but we're just not listening in the right way we can be much more assured that the earth is not presently colonized by aliens. At least leaving this guy aside but we'll come back to that. Broadly then we might
define the direct Fermi paradox as the following. It's an apparent contradiction that the earth has not
been colonized by an alien intelligence under the
assumption that aliens exist and occasionally engage
in galactic colonization. Okay so let me just quickly address the Ancient Alien stuff. Now some of you might reject the premise that the earth is
currently an alien colony. I mean after all maybe we are the aliens or we are somehow descended from aliens. After all Sir Ridley Scott liked that idea enough to make two
movies about it and look even within academia directed panspermia is recognized as a viable possibility as too is the possibility
of long-lost civilizations via the Cyrillian hypothesis. So I don't want to casually dismiss it but if we admit this is a possibility then the direct Fermi paradox loses some of its potency. So as a workaround to
this I'm going to switch out colonization for a
different kind of behavior. Instead let's consider beings who engineer a radical transformation
of a once habitable planet into a world inhospitable to biological beings such as ourselves. Almost like an anti-terraforming. This modification allows
us to retain a clean firm paradox. The earth is evidently
hospitable to biological life and so this transformation has not occurred. I'd presume such a transition to be permanent but even
if it wasn't the geological record excludes most versions of such an event like this
occurring in our past. Unlike the indirect Fermi paradox, we can't trivially
explain this away as being that we're just not looking
in the right way or something. It's categorical that
the earth is hospitable to life and thus the behavior in question has not occurred here. These planetary transformations could be occurring for a variety of reasons. It could be that an AI spreads out between the stars converting
all dumb matter into smart computer substrate. Effectively a wave of consciousness that spreads through the cosmos waking up the universe. It could also be a malicious intelligence that seeks to remove competition along the lines of the dark forest
or grabby aliens hypotheses. Or it could simply be a
rogue self-replicating machine that isn't even
necessarily intelligent at all but due to some
malfunction it spends its time shredding planets into more versions of itself. A so-called von Neumann machine. Now how hard is it for
us to imagine an entity capable of such feats? Consider that recently
many of us including on this channel have been startled by the capabilities of ChatGPT. With each iteration
and improvement many AI experts think that we
are on the cusp of AGI, artificial general intelligence. With some even claiming
that ChatGPT already shows hints of it. In that case we'd have
machines with autonomy and agency coupled with an intellect that exceeds any of us. It may very well be that
we are in the process of observing a planet-wide
transition from biology to technology. And even if this doesn't happen here, it's hard to doubt that it
never happens elsewhere. Especially given what even our diminutive brains are capable of creating
in relatively few iterations. At the same time, we're developing rockets capable of lifting over a hundred tons into space, robots that
can operate complex machinery, miniaturized space probes that can fit on your fingertip
and 3D printers lurching towards self-replication capability. Remember that all of these were once fantastical notions
but each is now powered by multiple businesses realizing these technologies. Now some of you might
question whether aliens would truly have the
capability of galactic domination though. Yes in our case AGI and robotics are on the horizon but
interstellar travel is notoriously difficult and something
we seem to be making far less progress on. However I think we only feel that way because of our limited lifespans. The truth is that interstellar travel is eminently possible. We've already sent out
five such probes ourselves. Voyager 1 and 2, Pioneer
1011 and New Horizons. All of them have speeds
exceeding the solar system's escape velocity. Now the reason why we don't tend to get too excited about them is because A, they have no passengers
on board nor support systems for passengers and B, they will take tens of thousands of years to cross the useful interstellar distance of a light year. But for an AGI these aren't problems. It doesn't need a habitat and it could patiently wait for millennia to reach its destination. The remarkable fact is
that even if you're limited to just chemical rocket systems, it appears possible to colonize the entire Milky Way galaxy on a
time scale of something like 300 million years or so. No need for warp drives,
fusion-powered ships or anything else. 300 million years certainly sounds like a big number but it's short enough that our 13 billion
year old Milky Way could have been colonized 40 times over by now. In fact the motion of the stars themselves makes this even easier. Modern simulations such as those by Jonathan Carrol Nellenbach
show that galactic domination can occur in the cosmic blink of an eye with waves of sentience
inexorably consuming the stars. Putting this all together then we have the Fermi Paradox
which has persisted for more than 70 years but it's
really just in the last few years that our view
has been fundamentally shifting at a rapid pace
especially that direct variant. Because many of the
empowering technologies that were once merely speculative are now becoming increasingly
likely, nay inevitable. Any claim of some kind of great filter that prohibits the development of such technologies is
rapidly becoming untenable. Despite this there's
still the open question of motivation though. Why would an AI or whatever kind of intelligence it is
want galactic domination? I think here in this case it's actually a little bit easier for us to
imagine possible solutions. After all the history of humanity is one of global domination, a story filled with many dark and tragic chapters. If our AIs are trained from our history, experiences and behavior then sadly it's not too difficult to imagine how this could be baked into them too. The sins of the father. And when it comes to galactic domination, it only takes one bad apple to
ruin the party for everyone. Perhaps 999 out of every 1000 AGI's have enough safeguards to never do this. I could totally believe that. But if just one of them
in 10 plus billion years of galactic history chooses to do this, just one of them through
either the AI equivalent of mental illness or
ruthless competitiveness or just downright malevolence chooses to do this, then we shouldn't be here. The direct Fermi paradox
then implies something genuinely paradoxical. This behavior seems perfectly possible and yet it has never happened, never in the history of our galaxy. Perhaps the simplest explanation to this conundrum is that we are alone. It was Michael Hart in
1975 and Frank Tipler in 1980 who first introduced a version of what I'm calling the
direct Fermi paradox. Tipler even titled his paper, Extraterrestrial Intelligent
Beings do not Exist, concluding this to be the sole explanation to this dilemma. In it he argued that intelligences such as our own will eventually develop a self-replicating universal constructor with intelligence comparable
to the human level and that such a machine could colonize the galaxy in less than 300 million years with present-day rocket technology. Tipler's ideas are particularly ominous in that he predicts that
the transition is being held back by a deficiency in computer technology and not rocket technology. I concede that Tipler's solution clearly naturally explains the Fermi paradox but I don't agree that
it's the only explanation. There is another possibility, one that actually dawned
upon me during a recent vacation a few weeks back. I remember when I had this realization I had to walk up and
down the beach for hours just thinking about its
profound implications. It's a resolution that allows us to have roaming AGI and our existence without any tension. Enter the weak anthropic principle. This principle is really just a statement of survivorship bias. To see it let's take a playful example of what I will call the water paradox. There's over 700 planets
and moons in our solar system but only one in 700 has
surface liquid water, Earth. Remarkably we find ourselves on that one world, a face value that
seems like an awfully improbable outcome, an
apparent paradox even. But in truth there is no paradox because of course we are
living creatures who likely could not have developed
on a dry waterless world. Water is a necessity
to our very existence. The fact that we live on a terracous globe is naturally explained
by the weak anthropic principle and I think we're all perfectly comfortable with that reasoning. So let's now apply that same reasoning to the different problem of
the direct Fermi paradox. Let's assume that intelligent life frequently arises within any given galaxy and that occasionally those intelligences go on to develop the means
to transform their galaxy from a collection of habitable planets to biologically inhospitable ones as described earlier. And yet we find ourselves living in a galaxy where this did not happen. Equipped with a weak anthropic principle though we see that there is no paradox. We necessarily must live in a galaxy where domination has not yet occurred. It's simply not possible for us to live in a galaxy devoid of
habitable planets since we require a habitable
planet in order to exist. Profoundly what this means is that it is quite possible that 99.99% of galaxies are completely infested
with colonizing AGI's and we of course do not live in one of those because there's
nowhere for us to possibly be. There's no cradle to birth us. To me this is a wonderfully elegant solution but it also implies something incredibly frustrating. Usually when we pose
versions of the Fermi paradox like this we do so in the hope of making some kind of intellectual progress of trying to maybe constrain something about alien life. And that was Tipler's goal to highlight the paradox as a vehicle for reaching a definitive conclusion. In his case the aliens don't exist. But Tipler was wrong to conclude that because of the weak
anthropic principle. At the same time he is possibly correct that we're alone but maybe
for the wrong reasons. It is perfectly possible that we are alone and obviously that naturally
explains the Fermi paradox. But so too does survivorship bias. And therein lies the
whole frustration here because unlike what Tipler thought there is no one singular conclusion that we can draw from the Fermi paradox. We can't neatly wrap this
up with this one idea. We are once again left clueless. In fact you know what? I would go a step further. I would say that the Fermi paradox is impotent as a tool for constraining the activities of alien life out there. So what is the upshot of all of this? Is there any hope of obtaining constraints barring a positive detection? Possibly. When it comes to the direct Fermi paradox the weak anthropic principle accommodates the possibility that AGI's
infest most galaxies. And if that's true we might
be able to detect them by looking outside of our own galaxy. When we look out a distant galaxy it's effectively decoupled from us. The distances are so vast that certainly with chemical rocket
systems there's no hope of intergalactic colonization. And what that means is
that if a distant galaxy goes on to spawn a
destructive roaming AGI, well that's fine. That has no bearing on our survival. And since survivorship bias is moot then the weak anthropic
principle is no longer in play. So if we could somehow design a survey to detect colonized galaxies that would be a fair and
representative sample from which we could deduce statistics. Remarkably extragalactic
searches for alien technology might be our
best bet for success as well as our most useful constraint. But of course therein lies
a formidable challenge. How does one detect a
galactic spanning empire from intergalactic distances? And what work has already
been done in that area? For answers to those questions you're just gonna have to wait
to a future Cool Words video because there's just too much to unpack there with the time that I have left. Let me finish by noting that
many of these conversations link back to the future
of our own civilization. Will we destroy ourselves
in nuclear conflict? Will our culture and technology stagnate and even reverse course? Will machines replace us all? The universe teaches us
that nothing lasts forever. There will be an end to
our story maybe tomorrow or perhaps a trillion years from now. I don't know how our story ends but the recognition of
an end is the recognition of finite time. We only have so much time to do the things we want to do both
personally and collectively. And for me the question
of life in the universe is right up there
amongst the best of them. It may even be our defining mission. So let us work together to try to reach that goal so that when our night falls we might rest easy knowing
that we accomplished our great task. So until next time stay
thoughtful and stay curious. (upbeat music) Thank you so much for watching everybody. I hope you enjoyed this video. If you did be sure to
like, share, subscribe. Let me just take a
moment to give a special thank you to our latest
donor that is Trevor Edris. Thank you so much for
your support, Trevor. If you too want to help us out right here in the Cool Words lab, then
you can use the link up above. Until the next video, see
you around the galaxy.
