As both a fan of, and writer of science fiction, there are few questions that loom larger in my mind than are we alone? Two great minds of the last century tried to answer the question, or at least lay the foundation for how we think about the problem. The funny thing was, they couldn’t have been more different in their approach.
Many of you are familiar with the famous Drake equation, which looks something like this:
You can read the meanings of the different variables at the link, but suffice it to say that even with very conservative estimates, the number of intelligent species out there are significant. This optimistic view of the volume of critters out there for us to talk to is shared by, well, pretty much everyone who writes books, movies, or television on the subject. Star Trek, Star Wars, Babylon 5, Farscape, Stargate, they all share the assumption that there will be a vast diversity of races out there ready to trade goods, technology, culture, and maybe even genes with if you’re a sufficiently charming Starfleet Captain. Indeed, the universes devoid of anything but human life, such as Firefly, are the glaring exceptions that prove the rule.
But there is another line of thinking that has proven to be just as persuasive that argues for exactly the opposite. This is known as the Fermi Paradox. In short, Physicist Enrico Fermi asks if intelligent life is relatively common in the galaxy, why isn’t it here already? The universe is billions of years older than the Earth. Our Sun is itself a young star. There should be civilizations many millions or billions of years older than our own. Why has not even one of them colonized the entire galaxy by now? Even without faster-than-light technology, colonizing the galaxy completely would only take a few tens of millions of years. So why is the Earth overrun with humans instead of aliens from a planet near Betelgeuse?
It’s a good question, and the implication is, since we aren’t overrun with aliens, maybe there simply aren’t any. However, I don’t find the Fermi Paradox compelling, largely because I believe it rests on assumptions that require just as much hand-waving as the Drake Equation might. Here’s an attempt to explain why.
Fermi’s first assumption is that intelligence and technology are necessarily intertwined. This is a rather human-centric assumption, and not at all true. We have several examples of intelligent races right here on Earth, such as dolphins, that have language, self-awareness, complex societies, but no technology. Nor is it likely they will ever develop technology on par with our own, not even if their brain development should one day match or even exceed our own. It’s not brain power they lack, it’s hands. Without hands, they are incapable of the precise dexterity needed to produce anything much more advanced than a pointed stick. Their aquatic environment poses another challenge. Living in water means no fire. No fire means no smelting or forging of metal tools. No metal means no radios, rockets, or other means of getting off world or contacting other sentients like ourselves.
With the explosion of extrasolar planet discoveries over the last ten years, there are very good reasons to suppose that many, many populated worlds are either super-earth water worlds, or roofed water worlds such as Europa. Indeed, they may well represent the majority of habitable planets and moons. Intelligent life in these environments would be very hard-pressed to develop technology beyond stone-age levels. The same limitations would apply to any life present in the clouds of gas giants. No ground means no workbenches. This represents an entire category of potentially intelligent life that would never have a chance to colonize space, yet could be waiting for us to show up in orbit and start a chat.
Furthermore, there are very good reasons to suppose that the galaxy has only been friendly to intelligent, technological civilizations for the last couple billion years, due in large part to the number of stellar lifecycles that were necessary to get to the concentrations of heavy metals we see today, elements that are crucial to any sort of technological advancement beyond the very primitive. It is possible that we are among the first generation of critters who finally have the potential to put plans of interstellar flight into action.
The next assumption I feel is an inappropriate analogy to the period of European colonialism applied to interstellar travel. Just looking at our own history of exploration and expansion leaves the core assumption that we should expect intelligent, technological races to spread across the sky without hesitation very suspect.
Looking at our colonial period, it becomes quickly apparent that we didn’t expand for its own sake. We expanded for resources, and usually only once the surrounding resources have been stretched to their limits. Economically, expansion even across the land masses of Earth was very expensive, an undertaking mostly reserved for nation-states. Exploration and colonization was motivated by profit, not the insatiable quest for knowledge we were told in school. New lands were stripped of easily extracted resources such as precious metals, gems stones, etc, all for shipment back to the home country. The exploitation continued beyond simple extraction when new land opened up to grow crops ill suited to more northern latitudes, especially sugar. Without this profit motive, colonies would never have been formed in the first place.
It is for this reason that colonization at interstellar distances should be anything but a given. Unless someone out there ever came up with an Alcubierre Drive, odds are we’re all going to be stuck at sub-light speeds, which would impose such a huge delay in travel times between the homeworld and even the nearest potential colony worlds, that trade between them becomes effectively impossible. This fact pretty much destroys the profit motivation for space colonization. Any expedition would be, from the viewpoint of the people actually paying for it, money thrown into a hole and burned. There would never be any hope of any return on their investment beyond pure scientific knowledge.
It will basically always make more sense, at least from an economic standpoint, for a species to simply find ways to live within their means on the homeworld. With this in mind, one would expect that if a species were to expand, they would only do so once the homeworld was no longer habitable, say due to their star moving out of the main sequence, as a last ditch effort to preserve the race from extinction. There’s a good argument to be made that not enough time has passed yet for ANY habitable planet with an intelligent, technologically advanced race on board reaching that point yet, and may not for another couple billion years. And even when that first generation of advanced races start jumping ship to new worlds, they’ll likely settle down and wait it out once more instead of spreading like a virus for no reason, because no matter how you slice it, interstellar travel by any theorized method, while possible, is still going to be really expensive.
Finally, and this is the clincher for me personally, if there’s one thing science has taught us over the last several hundred years, it’s that every time we’ve assumed our position in the cosmos to be unique or privileged, we’ve turned out to not just be wrong, but HILARIOUSLY wrong. From the Earth being the center of the universe, to our galaxy being the entire universe, to the rarity of planets and solar system elsewhere, and now finally to our unchallenged status as this planet’s only sentient race, reality has an unbroken track record of punching our ego in the gut and knocking us down a peg.
My gut tells me this will prove to be the case once again, so start funding NASA again for fuck’s sake.