I find that even most intellectually curious people have a bit of a mental block when it comes to deep time, especially in the forward direction. They may be somewhat comfortable with thinking of the history of life in tens and even hundreds of millions of years in the past, but they find it hard to take seriously the notion that life, including life descended from humanity, is likely to persist for the same order of magnitude of time, or possibly even longer, into the future. But this is a subject dear to me, as some of my long suffering farflung correspondents will know.
I find the radical right wing libertarian and AI-centric points of view equally (albeit for different reasons) repugnant. There are actually folks out there who think, what the hell, burn all the fossil fuel, don't worry about the millions who are starving, we just have to get to the future, some of us, and it will all work out. This is so wrong on so many levels. Our grand future in space is clearly not imminent. We are only taking the baby steps. In fact, I would say our enterprise to become an interplanetary, and eventually interstellar, civilization is almost certainly doomed to failure if we cannot first learn, as a baby advanced civilization, to live sustainably on our planet, and to cooperate as a species in a sustainable and, dare I say it, ethical, manner. And as for the AI singularity, all I can say is, don't hold your breath. I see no signs at all that we are anywhere near creating artificial consciousness. And as a corollary, I think the chances that AI will "take over" anytime soon, or that we will learn how to upload our minds into machines and live forever, anytime in the foreseeable future, are pretty much exactly zero.
But if you take seriously the idea that all of human history so far is but an eyeblink compared to the time to come, when intelligent beings evolved from the biosystem of this little planet a few thousand light years out into the calm and boring disk region of a fairly ordinary barred spiral galaxy, will emerge and begin to spread life from this world into a much larger space. It seems very likely to me, from recent research on exoplanets and the requirements for the origin and prevalence of life on this planet over several billion years, that planets like Earth, with advanced life, are probably quite rare, but environments where life can exist, whether artificial habitats or modified planetary surfaces, are abundant. But the stars are very, very far away, so the next phase(s) of our future, including the future of descendants who will not be entirely recognizable as human (in all likelihood) will take shape mostly in our Solar System. And for a long, long while, almost entirely on Earth itself.
But if there is a principle of all life, it is that it seeks out new places, and new ways, to live. So it is truly inevitable, unless we blow it completely and become extinct soon, that life from Earth will expand beyond Earth, beyond the Solar System, into a wider universe.
And, of course, as all science fiction readers will recognize at once, this begs the question, who is out there already? Is life common, even if it's just microorganisms? Are there other intelligent beings, who will have their own agendas that may not comport well with ours? What problems will our descendants face from the answers to these questions? And we don't know. We just don't. But we can surmise somewhat, and make some informed speculations.
I was reading the other day in a 20 year old book on the Fermi Paradox titled Where is Everybody? I didn't actually read the book, because there was literally nothing in it I hadn't already thought about and considered, and I found about 80% of it to be fairly useless. It devoted several chapters to the possibility that aliens are already here, on Earth, and we just can't see them. To me this is a preposterous idea that isn't really even worth talking about. If you disagree, I could debate you till the cows come home, but the arguments for this possibility aren't merely flawed. They're dumb, resembling QAnon conspiracy theories at their core, in that they require the most ridiculous special pleading of extremely unlikely concatenations of events and mass delusion to be possible. So, forget that.
Then there's the idea that "they're out there, but they're ignoring us," for whatever reason. I consider this almost equally ludicrous. Mainly because it completely ignores deep time. We're not talking about just the present. We can say, with near 100% certainty, that our biosphere has never encountered life that didn't originate here on Earth. The genetic code of all organisms, and even the most minute details of biochemistry, all point to a single origin of life, about 3.5 billion years ago, on this planet. If alien civilizations were close enough that they had ever visited this planet, we would almost certainly know it. And time is long. Stars much like the sun, and planets more or less like the Earth, have existed elsewhere in this Galaxy (and in countless other galaxies) for many billions of years. So there is no reason aliens would just happen to encounter Earth now, as opposed to long ago, when their likelihood to exist was about the same as it is now. And if they ever had, it seems very likely that they would have contaminated our biosphere with living organisms that did not originate on Earth. Think this through. Sure, it's remotely possible they could have been careful not to contaminate Earth with their life (we've already done that), and were only interested in studying us, not living here or changing anything. Sure. Could be. But all of them? In all time? And nowhere even a hint of their existence? It strains credulity. Same with the "Zoo" hypothesis, that they're out there watching us, or nurturing us, or whatever. This is like a conspiracy theory; it requires that all the supposed aliens have all conspired to keep their existence secret from us for huge swaths of time. It just doesn't make sense. Much more likely, I think, is the following set of inferences:
1. Life may not be terribly rare, but the evolution of stable, highly complex biospheres like Earth's, and perhaps even moreso the actual evolution of intelligent life in such places, is very, very rare.
2. One of the reasons for drawing that conclusion is that intelligent life is likely, in times short in comparison to the age of the galaxy or the time it takes life to evolve to Earthlike complexity, to figure out how to migrate through space and colonize other worlds, which process could proceed, again, in times short compared to the geological eras of nonintelligent life, to colonize the entire Galaxy, or even beyond.
3. QED: the most likely conclusion is that we are, indeed, alone, as a smart species potentially capable of interstellar migration, in a swath of the universe large enough that we do not see evidence of others like us, and enough time for the nearest of them to colonize our galaxy has not yet transpired.
I know this kind of thinking is anathema to a lot of people. They just can't take it seriously. But I think this is, really and truly, most likely the way things are. We arose naturally on Earth, from abiogenesis, a long, long time ago, and we have yet to encounter any other life from anywhere else. And the circumstances described above are why that is the case.
But what of other life that is not intelligent, not capable of interstellar migration, or comparable to humanity in general? Might this not be common? This is the great question NASA and other space programs are to a great extent dedicated to answering. But what are the implications?
It has occurred to me that non-Earth origin life could be extremely dangerous. Not that it would cause disease, but that it would change the course of evolution irreversibly, and that the introduction of even tiny quantities of living matter could be completely catastrophic and irreversible. We do not know the extent to which the course of evolution on Earth is purely contingent-- dependent on essentially arbitrary events that have shaped the way biochemistry works. We do know that natural selection is merciless... if organisms from another planet were better able to adapt to conditions on Earth, or elsewhere where we were trying to establish our form of life, they would be unstoppable.
I am not a believer in "Providence." The universe is miraculous in a sense, but it is not, I feel sure, guided by benign intelligence. For those who believe it is, wonderful, I hope you're right, and you are certainly entitled to your philosophy. But do we take chances based on wishful thinking? I think that the only prudent conclusion is that naturally evolved biospheres must assume the worst case, and must keep themselves isolated, completely, from all other life, forever. This needs to be an imperative.
And, just perhaps, I'd like to suggest, this is also one of the reasons we have no evidence of life from elsewhere. OK, it is a modification of the Zoo hypothesis. Maybe, just maybe, intelligent life that is smart enough to survive for geological time periods, invariably learns to avoid other naturally occurring life, as too dangerous to have any intercourse with. But that, too, would require perfection of intention and historical contingency, that leads me inevitably back to the supposition that, indeed, intelligent life must be very rare, and thus, other instances of it are likely very, very far away. Many galaxies away... most galaxies are likely, I think, completely devoid of intelligent life. But since we have the potential to spread out into our own Galaxy, over long periods of time during which we will evolve into other forms beyond all recognition, perhaps that's a form of unintended Providence, after all, because a crowded universe with competing civilizations would be a dangerous place indeed.
