A reader writes:
"And I think eventually we’ll learn to harness gravity, once we understand what the hell it actually is, and then this pesky Einstienein relativistic-light-barrier will fall soon after that."
Ain’t going to happen. Apples did not start falling up when Newton refined Aristotle’s physics, and time did not start running backward when Einstein refined Newton. No advance refutes the previous evidence–it only reinterprets it. Faster than light drive is as likely as a ride on the back of a fairy-magic unicorn.
"Assuming the aliens don’t arrive…"
Is there even the slenderest scintilla of evidence that homo sapiens is not utterly alone in the universe? I do not mean a semi-unsupported hypothesis based in turn on a totally-unsupported hypothesis about the origin of life from non-life, I mean evidence, something you can bring into a court of law?
You see, the scientific method assumes as an arbitrary postulate that the laws of nature and the conditions of nature do not vary from place to place: which means that they assume that repeating the conditions of the early earth in some other solar system would repeat the unknown miracle that created life from non-life.
But who can even count all the factors involved? Suppose only planets with liquid water can generate life from non-life? In our own solar system, we have exactly one world that may have had flowing water at some point in the past (Mars) and one moon or two which may have water now (Io, Europa). That implies water-bearing planets might be common. May be a lot of those.
But that is only the first factor on a list. Suppose only planets with tides? Not so many of those. Dinky moons like Phobos and Deimos won’t do. Suppose only solar systems with large gas giants to sweep away debris? There may be less of those. Suppose multiple star systems do not provide orbits stable enough for planets to develop life? That factor eliminates half the star systems in the galaxy, perhaps more. Suppose only stars with stable orbits around the galactic center are fit for developing life? Now we have even fewer. Suppose the correct concentrations of metallic elements in the local interstellar cloud, the correct concentration of the galactic magnetosphere, the correct shockwave of the heliopause belt of the local interstellar gas cloud — you see where this is going?
Because while we can pretend we know how life emerges from non-life, until we can do it in a lab, we actually don’t know. A guess is not a datum. There may be an unknown factor: the solar system a zillion years ago may have passed through a belt of interstellar e. coli bacteria left floating in a wide cloud in interstellar space by the noble yet doomed, long-lost race of the Panspermian Forerunners. It could be one of the factors on the list. We don’t know how long this list is.
I doubt the space-spore theory of the origin of life on Earth myself, but I cannot prove it false — a doubt is not evidence. Myself, I take on faith the idea that life emerged when Auðumla, the cosmic cow, licked Buri, the primordial being, out of the rime and frost of the yawning abyss called Ginnungagap — but faith is merely a reverse of doubt. It is an opinion, an article of faith, not evidence.
The idea that simple chemicals combined in the primal oceans, perhaps stirred by a lightningbolt, and fell into place as a long-chain ameno acid whose chemical alphabet spelled out a self-replicating (and grammatically correct) molecular sentence is as arbitrary as the story about the cosmic cow, but the only difference is that it does not posit any supernatural entities — an assumption and not a conclusion. It is an opinion, an article of faith, not evidence.
Even if planets capable of developing life were as prevalent in our galaxy as sperm in an ejaculation, if nature is as wasteful on a cosmic scale as she is on the microscopic scale, there will be thousands or millions of planetary bodies where life never emerged, even if all the conditions were exactly perfectly right.
I shall not bore you with reciting the other factors in the so-called Drake Equation, except to say that they are all unknowns. We do not know how frequently intelligence can emerge from non-intelligence even on worlds with life, or civilization emerge from barbarism, or technological civilization from civilization–as far as we know, in each case on Earth each of these events happened once and spread from that center: unless the Far Eastern and Middle Eastern civilizations arose independently, in which case we have two events. Hardly enough data points to hypothesize a trend: a universe where all planets develop to the level of the aborigines of Easter Island, who cannot maintain even a Neolithic level of technology, but stay trapped in the Paleolithic level, does not strike me as innately less likely than a universe crammed with galactic empires. As for the emergence of an interplanetary or interstellar civilization from a planetary one, that has not even happened once, so we do not even have a single data point from which to make a guess. It may be too unlikely ever to occur.
And if they are outside our galaxy, chances are that they will never generate a signal of any kind strong enough to reach us, unless of course they reach a level of civilization where interstellar war is commonplace, and they use weapons on the E.E. Doc Smith level of destructive waste, igniting stars into noavae and supernovae. That is, if they fought a galaxy-destroying war two million lightyears ago in Andromeda, we would be picking up the signal now; or if they fought a supercluster-destroying war one billion years ago in one of the dozens of clusters of galaxies in the Corona Borealis supercluster. But if the Andromedans only blew up the cities on the surface of one small iron-nickle core planet like ours, or several hundred thousand earthlike planets in one arm of the distant Andromeda galaxy, we would not see it. If the Corona Borealis creatures annihilated only a few smaller galaxies, ones we have not counted or named yet, I doubt we would notice.
And if we did notice, that would only tell us as much as the story of Ozymandias of Shelly: that at one time in the unimaginable far past a great peoples once lived. Except that we will not even have a Rosetta Stone to translate their boasts.
Who said: Two vast and trunkless legs of stone
Stand in the desert. Near them, on the sand,
Half sunk, a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them, and the heart that fed;
And on the pedestal these words appear:
“My name is Ozymandias, king of kings:
Look upon my works, ye Mighty, and despair!”
Nothing beside remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.
AN AFTERTHOUGHT: You may be wondering, dear reader, why if I am so skeptical about the basic SF tropes of FTL drive and alien First Contact, I do not therefore write Mundane SF, a subgenre is concerned with things happening on earth one block from my house taking place no further in the future than next week.
Good question! I am glad I put it in your mouth to ask me!
The reason is that I take these doubts as a challenge. Given the size of the universe, and the apparent rarity of life, given the Fermi Paradox, what explanation can I as an imaginative SF writer invent to make my story realistic-seeming enough to count as Jules Vern style Hard SF rather than merely be counted as STAR WARS or STAR TREK style adventure story that merely happens to be set in a scientifiction-flavored background? That is the gauntlet I have myself hurled at my own feet. Yes, I have some ideas I think make sense to explain away the paradox of the empty universe, and no, I am not telling. I came up with (or shamelessly plagiarized) at least two answers, and so I have at least two trilogies to write.
* * *
AN ADDED AFTERTHOUGHT: Let us dispense with the argument that, since the universe is so vast, any event, no matter how unlikely (including the creation of life from non-life), must have taken place at least once. By that argument there must be somewhere in the universe an exact replica of Earth with everything the same as here, except only that the opening of TALE OF TWO CITIES reads “It was the best of times, it was the blurst of times.”
The fact of the matter is we do not know by what natural process life can arise from non-life; hence we can make no good guesses about what conditions and preconditions are required for that process, nor do we know enough about the universe to know how frequently those conditions arise.
Let us suppose that one needs an earthlike planet for life to arise. This is a supposition only: for all we know, the clouds of rapidly rotating gas giants in closer-than-mercury orbits might be the prime real estate for life creation, and small rocky worlds like ours produce life on average only once every 15 billion years. Or the surface of neutron stars might be much more fertile of flat forms of two-dimensional life than any world. But leaving that speculation aside, let us assume rocky Earthlike worlds high in metals is the most fertile of soil to spontaneously give rise to organisms. Recent discoveries of exosolar planets have delighted astronomy buff and/or SF geeks(like me) world wide, and certainly cleared one of the basic obstacles: but keep in mind that an assumption of uniformity is merely an assumption. Assumptions are not facts. What if we just so happen to be in the midst of a rather thickly seeded area of the cosmos where planetary development is frequent? What if there is some peculiar property of the Hyades Cluster or the Orion Arm that makes this particular Local Interstellar Gas cloud in which the nearby stars hang particularly favorable to the development of planets?
For example, in the famous Lensman series by EE Doc Smith, the author there postulates that planets are created by near-collisions of stars, and therefore only a galaxy that intersected another galaxy edge-on would have abundant planets. All other galaxies are sterile. As a science fiction conceit, this is not as far fetched as other ideas (such as inertialess drive) — if it or something like it were true, no study of the likelihood of planets developing in our galaxy would necessarily tell us the likelihood of planets developing in other galaxies.
In other words, the argument that the mere vastness of the universe allows for any unlikely event (such as life arising from non-life) to happen frequently, is an almost meaningless argument. It is an almost meaningless argument because the word event can be made to cover anything, large or small: including the event of discovering that you are utterly alone in the universe. If the unlikely event were the development of planetary bodies in the Milky Way galaxy, and all other galaxies were as devoid of planets as Luna is of atmosphere, then even the study of our local conditions proves nothing about conditions elsewhere.