Ours is a science-fiction family.
That fandom probably explains our fascination with the possibility of extra-terrestrial life, and conversations in which we exchange theories about why no representative of other civilizations has ever contacted us. (I continue to assume that reports of alien abductions and Roswell conspiracies are evidence of something other than intergalactic visitations.)
The article begins with the math. Using the most conservative estimates, there are 500 quintillion, or 500 billion billion sun-like stars, a 100 billion billion earth-like planets, and 10 million billion potentially intelligent civilizations in the observable universe. If we limit the calculations to our own galaxy, and use the lowest estimate for stars in the Milky Way (100 billion), that would come to 1 billion Earth-like planets and 100,000 potentially intelligent civilizations in our galaxy. (The bases for these estimates is in the article.)
So: why hasn’t anyone called? Written? Why hasn’t SETI picked up any signs of such civilizations?
Welcome to the Fermi Paradox…
In taking a look at some of the most-discussed possible explanations for the Fermi Paradox, let’s divide them into two broad categories—those explanations which assume that there’s no sign of Type II and Type III Civilizations because there are none of them out there, and those which assume they’re out there and we’re not seeing or hearing anything for other reasons.
For his part, my son is convinced that civilizations get to a certain point in their development and destroy themselves–that technological innovation outstrips social progress/maturation, and they self-destruct. (As he notes, perhaps they are unable to combat climate change in time)… In the Fermi Paradox, this theory is called The Great Filter.
The Great Filter theory says that at some point from pre-life to Type III intelligence, there’s a wall that all or nearly all attempts at life hit. There’s some stage in that long evolutionary process that is extremely unlikely or impossible for life to get beyond.
There are more comforting theories.
Super-intelligent life might have already visited Earth before we were here. Sentient humans have only been around for about 50,000 years (assuming we can consider humanity sentient–see Wednesday’s post)…Or we might live in the galactic equivalent of “the sticks”–some out-of-the way part of the galaxy. Perhaps civilizations that endure lose interest in exploration. Or on the other hand, maybe there’s only one such civilization, and it’s a “superpredator” (the Borg??) devoid of what we would consider ethics, that exterminates (or assimilates) other intelligent civilizations once they get past a certain level.
Or maybe there’s plenty of activity and noise out there, but our technology is too primitive to hear it, or because we’re listening for the wrong things.
Like walking into a modern-day office building, turning on a walkie-talkie, and when you hear no activity (which of course you wouldn’t hear because everyone’s texting, not using walkie-talkies), determining that the building must be empty. Or maybe, as Carl Sagan has pointed out, it could be that our minds work exponentially faster or slower than another form of intelligence out there—e.g. it takes them 12 years to say “Hello,” and when we hear that communication, it just sounds like white noise to us.
Of course, it’s also possible that super-intelligent civilizations have created a tightly-regulated galaxy–sort of like Star Trek’s Federation– in which Earth has been labeled a “no go” zone because we’re part of a strict “Look but don’t touch” rule applicable to still-uncivilized planets.
As the author of this explanatory piece notes in his conclusion,
Beyond its shocking science fiction component, The Fermi Paradox also leaves me with a deep humbling. Not just the normal “Oh yeah, I’m microscopic and my existence lasts for three seconds” humbling that the universe always triggers. The Fermi Paradox brings out a sharper, more personal humbling, one that can only happen after spending hours of research hearing your species’ most renowned scientists present insane theories, change their minds again and again, and wildly contradict each other—reminding us that future generations will look at us the same way we see the ancient people who were sure that the stars were the underside of the dome of heaven, and they’ll think “Wow they really had no idea what was going on.”
Hard to say.
I’m just hoping my son’s theory is wrong–and if it’s right, that we don’t hit the Great Filter for a while…