The other day I was Wiki Walking and ended up reading about the Rare Earth Hypothesis in reference to the Fermi Paradox and the Drake Equation. We’ve discovered that most stars in our galaxy appear to have planets of some kind, although ones with human-friendly environments may be quite rare. The presence of a plethora of planets presumably provides a potentially large factor for at least one part of the professor’s pretty problem.
But it’s possible that some of its other factors are extremely small. They may be much smaller than anyone had imagined. They may be so small as to ensure that we are alone in the galaxy.
It’s even possible we are alone — or nearly alone — in the universe!
Science fiction fans may be familiar with the Drake Equation (DE). It dates back to 1961, and was created by Frank Drake as a way to quantify the number of civilizations in the galaxy. Essentially, the equation starts with the total count of stars and multiplies that against several reducing factors. The final result is a (possible) count of planets with intelligent life.
The reducing factors take into account things like: not all stars have planets, not all planets are in habitable zones, life may not develop on all habitable planets, intelligent life may not always develop. (See the Wikipedia article for the specific factors.)
A great deal of science fiction assumes the DE results in lots of intelligent alien races scattered throughout the galaxy. TV science fiction often tends to assume most of them look somewhat like us, but that is more a limitation of special effects (and perhaps a failure of imagination).
Some stories have used the idea that the galaxy was somehow seeded by a race, and that’s why so many aliens look humanoid: they’re all based on the same basic model. Star Trek used the idea (in the TNG episode, The Chase, season six), and the movie Prometheus is based on the idea.
There is also a scientific concept, panspermia, which suggests that simple life forms could live in space and seed planets via falling meteors. The DE, and ideas like panspermia, are what gives hope to missions like SETI and the Arecibo Message.
And as I’ve mentioned before, I long for alien contact!
But the Rare Earth Hypothesis (REH) may dash all those hopes. (And, sadly, SETI has turned up nothing in a search that has been ongoing in some fashion since the 60s and has been in high gear for almost 20 years.)
The REH is one answer to the Fermi Paradox, which asks the obvious question: Okay, so if alien life exists… where is it?
The Paradox has many potential answers. A classic one is that aliens deliberately leave us alone until we’re “ready” or “worthy.” But generally speaking, it’s not unreasonable to believe that if aliens did exist, we would have seen some clear sign. (Isn’t it funny how the UFO craze seems to have evaporated now that just about everyone carries a video camera with them at all times?)
Given human nature, it seems unlikely that all aliens would go along with a program of leaving us alone. But as I’ve pointed out before, even in the 60s we understood the value of a “Prime Directive” (even if Kirk did violate it more often than not). By the time Picard came along (late 80s), we were much clearer on the idea. Perhaps by the time we actually (seriously) reach space, we’ll have grown up even more and will fully embrace such principles.
Or it could work like the opening to Hitchhiker’s Guide to the Galaxy, and we’ll be wiped out for merely being in the way and too unintelligent and primitive to get out of the way.
Our galaxy is billions of years old. A space-faring species could explore and colonize the entire galaxy easily within a million years using technology we can foresee today (specifically: no faster than light travel). Certainly if life is common one would think we’d have seen some indication.
The REH suggests that life is extremely uncommon. It may be so uncommon that we are alone in the galaxy (which is why we’ve seen no signs of other life). It’s possible that the probability of life in an entire galaxy is less than 1. We happened to beat the odds, but other galaxies may be devoid of complex, let alone intelligent, life.
It may turn out that single-cell life is somewhat common. Here on Earth we find life everywhere, even in extreme places such as deep-sea vents and volcanic pools. Bacteria have been found deep in the Earth. (I have some doubt even on this. To me, RNA is one hell of a jump up from organic chemistry. I have not heard a good account of how amino acids evolved into RNA.)
Multi-cellular life seems to need mitochondria to provide the necessary energy, and one theory is that mitochondria were a very low-odds accident where a smaller single-cell critter became a symbiote to a larger single-cell critter, and over time the relationship became permanent.
Many believe that our large moon was a key factor in the development of life. The moon creates strong tides, which means tidal pools. Life adapting to the daily transition may have been thus encouraged to make the jump from ocean to shore. However, others point out that the process (we think) that formed our moon — debris gathered in the Lagrange points — is a common phenomenon. Moons, obviously, are common in our Solar system.
So the REH says we don’t see evidence of other life, because there isn’t any other life.
A rather disturbing answer to the Fermi Paradox is that intelligent life always ends up killing itself off. Or possibly dying off due to apathy when individuals become too engrossed in their TWITs and Angry Birds and no one learns the skills necessary to ‘keep the train running.’ (Does that sound like a civilization you might have heard of?)
One of my favorite bits in the aforementioned Hitchhiker’s Guide to the Galaxy concerns the planet of Golgafrincham. The people there decided to rid themselves of the “useless” one-third of the population: the insurance salesmen, management consultants, hairdressers, telephone sanitizers, etc. They concocted a story about a threat to the planet and built three “Ark” spaceships, packed those folks into the B-Ark and sent them off with promises that the rest would follow in the other two arks.
The rest of Golgafrincham heaved a sigh of relief and got on with life. Only to die out shortly thereafter from a deadly disease spread via dirty telephones.
(It turns out that the B-Ark crash landed on an “utterly insignificant little blue-green planet” circling a “small unregarded yellow sun.” Yep, that’s right. We’re the descendents of the useless Golgafrinchams!)
As I look around at the world today, I have to say: I can’t help but wonder if self-destruction isn’t in our future. We muddle along with a value system that doesn’t seem designed to insure survival.
Some days I think the only real question is: what form will our self-destruction take?
I’ve got $500 riding on “Virulent Disease” but, win or lose, I’m not sure how one ends up collecting on that bet.