by Jasper Gilley
As the human species has carried on with its pattern of continual expansion and the making of first contact between various hitherto-separated locales of humanity, a pretty significant question we’ve come across is: where is the next civilization with which we’ll make first contact? This seems like a pretty irrelevant question until you consider the fact that the universe is unbelievably big and old, and somewhere in there, another “advanced” civilization should have developed that would make first contact with us! Current estimates for the age of the universe range from 13.5 to 14 billion years old, with a 59 million year margin of error. And the observable universe is a sphere about 92 billion light-years in diameter.
Of course, when looking for “advanced” intelligent life in the universe, one must factor in the number of planets that orbit in the “habitable zone” of their star and the number of planets that have water (we don’t yet know of any substance that can support life like water can), but still, there should be a lot of planets capable of supporting “advanced” life. Additionally, the Sun is a pretty normal star, and there should be lots of similar stars far older that might have spawned a civilization capable of coming to us, or at least sending us some messages. In fact, this unresolved question of the apparent absence of advanced extraterrestrial life seems so strange to some that it has become known as the Fermi Paradox, after Enrico Fermi, an Italian physicist who first started asking these questions.
Now, this bars the possibility that first contact has already been made, and we are living in a simulation a la The Matrix. We can’t just entirely brush away this possibility since it would be a perfectly viable explanation to the Fermi Paradox: hypothetically, a hostile alien civilization came to Earth thousands of years ago and made humans incapable of accessing the base reality. Unfortunately, simulation theory is somewhat of an axiom, since there’s no way to disprove it. Therefore, we’re going to assume it isn’t the case (sorry Elon Musk) in order to continue discussing the Fermi Paradox.
One interesting thing about the Fermi Paradox is that it’s only as accurate or helpful as those who thought of it (namely, humans), and we as a species have a fundamental assumption about evolutionary biology that isn’t necessarily true. Namely, our definition of what qualifies as an “advanced” species is wholly dependent on our own characteristics! In other words, we judge the “advanced-ness” of other species relative to the strengths of the human species. Of course, our species has innumerable qualities that distinguish us from other species, but the most fundamental of these is our technological adeptness. What really sets us apart from monkeys and algae and koalas is the fact that we’ve developed the wheel, the catapult, the printing press, the internal combustion engine, and the internet, and therefore we naturally judge the developmental level of monkeys and algae and koalas by how much they measure up to our technological achievements.
Additionally, all natural selection really cares about is how many offspring we have, so any other defining characteristics are icing on the evolutionary cake. But there are a plethora of other defining characteristics that a species might have aside from technological adeptness! You could just as easily measure evolutionary success by population size (in which case bacteria would beat us handily), body size (in which case whales would beat us handily), adaptation to an extreme environment (in which case anglerfish and archaea would beat us handily), or a number of other “icing on the cake” defining characteristics. To reference an apocryphal Albert Einstein quote, “everybody is a genius, but if you judge a fish by its ability to climb a tree, it will spend its whole life thinking it is stupid.” (Einstein never actually said this, by the way. The quote first appeared decades after Einstein’s death in a self-help book, but it’s still relevant nonetheless.)
Therefore, the civilization that we’re really looking for that will fulfill the Fermi Paradox isn’t an arbitrarily-defined “advanced” civilization, but rather a technologically adept civilization. This is a much less arbitrary definition, and what’s more, we can actually think scientifically and probabilistically about the Fermi Paradox now. First of all, there have got to be some funky and unique evolutionary pressures that will give a species the defining characteristic of technological adeptness. Of course, evolutionary biology on the whole has no idea what the probability of this development occurring is. There are countless species that are defined by large population size, or large body size, or adaptation to an extreme environment, but only one species that is defined by technological adeptness. There are currently about 8.7 million eukaryotic species in existence, and between 1 and 4 billion have existed on Earth, ever. That suggests the probability of technologically-competent life arising on a biologically diverse planet is equal to
Of course, this also assumes that other planets are equally as likely as Earth to develop technologically advanced life, that is, it assumes that life develops (broadly speaking) in a linear fashion. On the contrary, it’s very possible that as you are talking about more and more remote evolutionary possibilities (and technological competence is a pretty remote possibility!), the probability of that existing gets logarithmically lower and lower. This expression is therefore pretty generous.
This adds an entirely new factor into exobiologists’ criteria in the search for planets with “advanced” life, and diminishes the probability of finding said life very significantly. A planet with life comparable to ours must:
- be in its star’s habitable zone
- have liquid water somewhere
- have microbial life
- have sufficient biodiversity to support development of technologically-advanced life
And obviously, the fourth criterion is the critical one. From what we can currently tell, there are lots of stars like the Sun, and lots of those stars have planets, and some planets are in their star’s habitable zone, and a few of those have liquid water, and a very few of those might have microbial life, and we don’t know the frequency of planets that meet the fourth criterion, but all indicators suggest it’s extremely small (orders of magnitude smaller than any of the other criteria.)
Looking at the situation biologically, it’s easy to see why the Fermi Paradox exists. Moreover, the Fermi Paradox seems pretty redundant. Most of the time, we kind of take for granted that planets with life are going to have advanced life sooner or later, and this is pretty clearly not the case. It may be a while yet before first contact is made.
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