Man, has it been almost four years already?
Last time around I talked about the notion of the Great Filter(s), and where we stood in relation to that, and whether we were past it or whether it yet lay ahead of us.
Consider that particular box of the paradox checked.
Which brings us back to the question of “where is everybody?” Because if we accept the notion that we’re past the Great Filter(s), and that we’re at the very beginning of becoming the First Galactic Empire (that we know of), we also have to accept the probability that with hundreds of billions of stars, and potentially trillions of planets orbiting them, that someone else has made it this far and yet, not populated the galaxy. Or at least produced evidence of their existence that we can detect from our little corner of the galaxy.
So let’s talk about why that might be the case.
First, let’s talk radio. No pun intended. The fact of the matter is that, in terms of broadcasting our existence to the galaxy, our radio shell is rapidly dissipating and outright vanishing, because as technology improves, just spamming omnidirectional broadcasts turns out to be a relatively inefficient way to conduct the business of transmitting information. And there’s no reason to assume that we’d be unique in this regard; realistically, all civilizations would come to the same conclusion, and as a result, the window of detectability, if you will, is vanishingly small on a cosmic scale, to say nothing of the fact that even at the height of our broadcasting phase, we weren’t transmitting with enough power to be intelligible past a few light years.
So we can check one more box off the paradox.
Next, the ubiquitous “alien megastructures” concept. Dyson spheres, swarms, ringworlds, Kardashev scales (not to be confused with Karsdashian scales), and so on.
I mean, if you ask some science fiction authors, the concept seems inevitable, but realistically, why? Technology tends towards greater and greater efficiency, doing more with less, and there’s no reason to expect that to change. Yes, our power needs are constantly growing, but that is in no small part because the vast majority of the planet still lives in what most of the people capable of reading this blog post would consider crushing poverty; eventually, we’ll be past that particular hurdle and exist in a post-scarcity society where, among other things, we’ll be forced to recycle basically everything since that will probably be a much more efficient use of energy than just, for example, shooting all of our trash into the Sun. Which, coincidentally, will reduce our visible signature to the rest of the galaxy.
Not only that, but every indication is that once societies actually reach a comfortable middle class existence, population growth grinds to a halt, or even goes into reverse. We may wind up populating Mars in my lifetime, but we’ll probably be siphoning the most adventurous types right out of Earth’s gene pool in the process, at least in the long run. And while a limited Dyson swarm does seem to be one of the better ways, at least early on, to conduct asteroid mining operations via vast mirror arrays, you wouldn’t need an array all that huge for the process, and eventually you’d run out of things to use it for. I mean, there are only so many people who need a solid gold toilet, after all.
A Dyson Sphere may seem like the ultimate evolution of an intelligent species’ mastery of its home system, but we have no idea if it’s even possible to do, much less what it would look like to a telescope if it is. And again, the question of “Why?” must be asked; if you’re not making more people in any particular amount, you don’t need the real estate, and if you’re moving towards ever-increasing efficiency in your technology, you don’t need the power.
So. Another box off the paradox.
Now let’s talk beacons, the notion of civilizations actively broadcasting their presence to the stars in an attempt to make contact with other intelligent life. Well, it’s possible we caught the fringe of just such a signal once in the past, but if we use our one major such transmission as a model for what such an attempt might look like…
The Arecibo transmission was sent to a cluster of stars 25,000 light years away, and it lasted a grand total of three minutes. Which means that of the stars that might hold intelligent life in that particular cluster, they’ll have to be actively listening for those three minutes, 25,000 years from now, in order to receive it at all, and then we’ll be stuck waiting another 25,000 years for a reply… which we probably won’t care about by then anyway, if we even remember that we called them in the first place.
Incidentally, we sent a reply towards the source of the Wow! signal back in 2012, just in case it turned out that it had in fact been the edge of some attempt at communication. Unfortunately, that reply took the form of 10,000 Twitter messages, thus proving to whoever might have sent it that there is no intelligent life on Earth.
Now, it’s possible that a much more advanced civilization might create some sort of omnidirectional beacon, with enough power to reach out far enough to be detected by nearby intelligent life that happens to be listening, but by the time you’ve got the spare capacity to invest in that sort of project, judging from our own progress, there’s a fair to middling chance that you wouldn’t need to; you’d just beam your messages towards stars where you can detect evidence of intelligent life via other means, but that requires a technological civilization of a certain level of sophistication, meaning that if such an advanced race existed a mere 200 light years away, practically neighbors in galactic terms, they wouldn’t be able to detect us just yet. And once they did, it would be another 200 years before we heard from them.
And now to one of my personal favorites in the “why haven’t we seen X?” series, the interstellar probe.
So it’s conceivable that we have seen such a probe (vanishingly unlikely though it may be), it’s just long dead. But realistically, you’re back to the fact that we’re not likely to be sending serious probes at planets we don’t know harbor life, so we can assume that nobody else would be quite so wasteful either, and the fact remains that unless such a probe was incredibly advanced, it would have to arrive, stop, and then linger in position for a time span so incredibly long as to largely prohibit the possibility that it would remain functioning on the off chance that intelligent life actually arose in the target system.
Hell, for all we know, we’ve had a dozen such probes fly through our solar system, report back to their homeworlds that there’s nothing of note here except some really big lizards, and then quietly die somewhere out in the distant reaches of space.
So in all likelihood, if we ever do get visited by an interstellar probe, it will be one specifically dispatched after we are detected as an intelligent civilization, and barring some loophole in physics as we know it, that means that any such probe likely won’t arrive for centuries at the very earliest.
“But what about Von Neumann probes?!” ask the sci-fi fans in the audience, to which I reply “Hopefully nobody is that stupid!”
We talk about the potential horrors of nanotechnology, the “gray goo” apocalypse, but Von Neumann probes are just that on a macroscopic scale. Even if we assume a technology vastly advanced beyond our own, the concept of sending anything capable of self-replication out into the galaxy is so wildly irresponsible that I pray it never occurs. Space is an incredibly harsh environment, and it would take just one probe to get just one line of code garbled before it decides to start disassembling entire star systems in order to make more of itself.
And the checking of that particular box leads us to the last real problem child of the paradox, the notion of robotic ships carrying frozen embryos that will be raised by robots upon their arrival at the target star system. It’s a concept that’s been explored in science fiction a few times that I can recall; rather than send whole humans in some sort of cryonic suspension, it would be vastly easier to send a cannister of fertilized eggs, much lighter and easier to shield against long term damage from cosmic radiation, and you’re going to need the robots to be slaves for the human colonists anyway so why not just skip the middleman, so to speak, and zip a few dozen of those suckers out into the void to search out and colonize strange new worlds, and possibly encounter strange new civilizations?
Except for the aforementioned problem with Von Neumann probes. Because this would probably be one of them. Any such machine would have to be capable of self-repair at the very least, and more likely, since you wouldn’t want to pack an entire industrial civilization into your compact starship, you’d make it capable of replicating at least portions of itself. And the more powerful and complex you make your robot, the greater the potential for disaster if something goes wrong.
Where does that leave us?
It leaves us in a universe where we probably won’t be able to detect another civilization until we’ve got telescopes big enough to actually see them; they probably won’t be any better in that regard than we are; there are probably no vast fleets of probes out there in the universe scouring the stars for intelligent life, and colonizing other worlds once you find one that actually supports life is going to be hard, since the only really ethical way to do so is going to be the slow boat to the stars, a vessel large enough to make the journey while housing a full living seedling of human civilization within it, tens of thousands of people willing to live and die in an artificial environment and condemn their children for generations to come to the same fate, just so they can get to a planet and…
Do what, exactly, that they haven’t already been doing? I mean, after a journey of thousands of years, dozens of generations, will they even care about settling on a planet at that point? Will they be willing to adapt to a potentially radically different environment than the one they’ve always known, or would they rather just settle into the local equivalent of the asteroid belt and crank out a few O’Neill cylinders every now and then until they get complacent and… senesce.
What’s more, how long would a civilization be willing to expend the sort of resources necessary to launch such massive interstellar arks? Each such vessel would be a fairly massive undertaking, even if you assume that robots are doing all the work, and then you have to find the people willing to take the leap, and once you’ve launched a few dozen, would there really be a point to continuing? I mean, barring the discovery of biological immortality, there’s no way that any person living at the time an ark is launched will ever get to see a message sent back to the Earth from a fledgling colony. And if you do discover a means of living forever, who the hell is going to go off into the depths of space in the first place? Who are you going to find that would be willing to trade eternity (likely eternity in a virtual Matrix-esque paradise, at that) for a pretty fair chance of dying in deep space if something goes wrong, solely for what, the spirit of adventure or even the survival of the species?
There are limits to both adventurism and altruism, and I suspect that by the time we can put together such an endeavor, you’d be hard-pressed to actually put together a crew without resorting to some pretty monstrous forms of societal (and probably genetic) manipulation.
So there you have it: The other half of my take on the Fermi Paradox. Make of it what you will.