Long Post: Why is it so quiet out here?
Published February 21st, 2007(This is the first in my series of “Long Posts” - meaning, I was bored, find the subject fascinating, and just love reading and babbling about it. And of course I encourage discussion, if any of you get down far enough to the comment box.)
Have you ever stared up into the night sky and asked “Are we alone? Is there anyone or anything with a brain out there?” Obviously the answer is - we don’t know. In all of human history, no one has ever been able to prove the existence of extraterrestrial life. Ever.
That said, no one has ever proven the complete lack of it either. And there’s absolutey no evidence to prove they’re out there, but again, lack of evidence is not evidence to the contrary. This question is fundamental to the human experience. And if either answer is ever proven, it will be the most important scientific discovery - especially if it’s intelligent life.
The history of humans wondering is not a short one. We tend to think, for some reason, that the modern era is the first where people have wondered about who else might be in the universe. But that isn’t so. Of course, for most ancient civilizations, the concept of an off-worlder would pretty much be indistinguishable from the concept of a god, deity, spirt, etc. But in a few cases ancient civilizations came up with thoughts on ET life that really aren’t much different from our speculative fiction authors of today. In fact, you could say that science fiction stretches back all the way to the Roman era, to a man named Lucian. You see, Lucian came up with stories of travelling to the moon and Venus, of extraterrestrials and inter-planetary war. And I think I just read a book about that recently….the point being, this was around 150 AD. Makes HG Wells and Jules Verne look like they were pretty late to the party.
The Jewish Talmud discusses other worlds and other beings, though it states that none will have the free will of humans. The Ancient Greeks pretty much made the concept of other worlds impossible, given their view of the universe. And when Christianity rediscovered the Greek cosmology, they adapted it almost word for word - except that part. In 1277 the Bishop of Paris opened the door by saying God could have created more than one world - but divine revelation says that he only created one. Well, that opened the door for speculation, and so people did speculate. In the 1400s Cardinal Nicholas of Cusa speculated about alien life on the moon and on the sun.
Along came the telescope and with it, more fantastical speculation. Bruno, a priest in late 1500s Italy, came to the conclusion that all these stars must have worlds around them. He had bought into the new science of heliocentrism and couldn’t imagine all sorts of stars out there, created by God, just to be pinpricks of light at night. He, of course, was burned at the stake for being a heretic.
After Bruno though, the gates really opened. There is no shortage of philosophers and scientists thinking about other worlds and other life. I think that’s really a function of the human mind - we simply cannot imagine that we are all alone. Every civilization has stories of extra-special beings, different from humans, whether they be gods or monsters, aliens on the moon, around other stars or from the center of the earth. We seem to have an innate need to not be the only intelligence around. Maybe it’s an inferiority complex. But that brings us back to the Fermi Paradox - why don’t we have even the slightest shreds of evidence that we aren’t alone?
Right now, exoplanets are being discovered almost every month. We’re just getting started, but so far it looks like planets are almost ridiculously common. So far our technology only allows us to detect the largest of worlds - but within a decade we will be able to detect planets of earth size. That’s right - within just about anyone’s lifetime who’s reading this (assuming anyone has gotten this far), we will know if there are other earths out there - and if they could support earth-like life. Just this week, for the first time, we have analyzed the composition of an exoplanet’s atmosphere. And it wasn’t what we expected. I think there are going to be a lot of suprises in this field. So planets are common, earth-like planets are very probably (and I think they are) very common as well. The Rare-Earth hypothesis is pretty close to being disproven. But do they have life? Do they have intelligent life? If so - where’s the noise?
The galaxy is a big place. Unfathomably big. Hundreds of billions of stars, billions and billions of planets. And there are hundreds of thousands (at least) of galaxies. But the distances are VAST. Unbelievably so. If an alien is out there listening for a radio signal, he’d have to be within about 50 light years of earth to hear us. The galaxy is 100,000 light years across, and 1000 light years thick. It’s like yelling from a mountain top in California, and the absolute nearest person that might hear you is on the moon. And they’re probably further than that.
The numbers are mind-boggling, and you’re thinking - well, sounds like they’re never gonna hear us, and we won’t hear them - it’s just too far. The flip side here is that the galaxy is really old. Even at a glacial, conservative sub-light speed ship expansion rate, a space-faring race could colonize the galaxy in about 50 million years. For some scale here: the galaxy is 12 billion years old. The earth is 5 billion. The dinosaurs died 65 million years ago. So if a race jumped off their planet and started spreading out when the dinosaurs died, they should have been here a long time ago. Maybe even before we stood up and started banging sticks on things.
Two possibilities - we’re alone or we’re not. Are we right to assume that the perils of a sentient race are universal? That they’re fairly likely to blow themselves up in a war, get hit by a meteor before they can get off the planet, or possibly just evolve into something different? Maybe. But by sheer numbers - they should be here. We should know. And that’s what’s so scary - there’s nothing. By Ockham’s Razor - we’re alone. Very alone.
So maybe science-fiction authors are wrong - especially the Roddenberry-types out there who dream of untold numbers of beings - and even the McDevitt-types who write of a nearly empty galaxy. Because we’re still looking at zero.
I’m not ready to give up though, and neither are most ET-hopefuls. We can come up with many, many reasons why it seems that we’re alone. Maybe one is right. But once again - we don’t know either way. But we should never stop trying, because answering this question is one of the most important questions we can ask. And throughout history, we keep asking it. It’s not a question that will go away, and it’s not a question that is reserved for nerds and crackpots. There is an unbelievable amount of research out there, and if this stuff has piqued your interest at all, I recommend seeking it out. I love this stuff - hopefully there will be an answer in my lifetime. I can’t wait for the next generation of planet-hunting telescopes.
There is no shortage of speculation right now, in either direction. Either the galaxy is ours for the taking, to spread life throughout all we can see, or it isn’t - and we need to get moving to stake our claim.
Keep watching the skies…
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