Hello aliens! We are naked, and also kind of lumpy.
Author's Note—This is a piece about the universe, aliens, computers, bastards and why there may not be, but probably are,
alien computer bastards. It's long, long enough that this is only part 1 of 3. And you know how much you hate things like that. It will not help anyone win the Iowa caucuses. Plus... there's math. It's simple math, but still. Math. On a Sunday. If I were you, I'd just skip it.
If you do step past the great orange gate to see what's inside, expect to be confronted with possible answers to the Grand Mysteries of Creation™. Including, but not limited to:
- What is real?
- Where is everyone?
- And why does everything suck so badly?
You've been warned.
People like to imagine there are big signposts spread out across history–Here There Be Bronze Age and No Hunter-Gatherers Allowed. But most of history's transitions are a good deal more messy. They don't start when you think. They don't end. Ever.
Still, there are moments. Moments when something happens that completely changes the possibilities for humankind. Only most of those moments, we don't notice. Take this one for example.
"...near some star rather like the Sun there are civilizations with scientific interests and technical possibilities much greater than those now available to us. To beings of such a society, our Sun must appear as a likely site for the evolution of a new society. It is highly probably that for a long time they will have been expecting the development of science near the Sun. We shall assume that long ago they established a channel of communication that would one day become known to us..." — Giuseppe Cocconi and Philip Morrison, Cornell University, 1959
The publication of this paper in 1959 showed that humanity had just hurdled an incredible barrier. Radio telescopes had been developed that were sensitive enough to enable something that was, both then and now, quite astounding: communication with an alien civilization around some other star.
The original paper from Cocconi and Morrison mentioned a few things about which we were then completely ignorant. Were planets common around other stars? If there were planets, what about life? And if life, then what about intelligence?
We now know a bit more about the first couple of questions. We're drowning in exoplanet discoveries. Now that we know how to look, and have instruments sensitive to make a search, we can see that the universe is simply lousy with planets. We've discovered hundreds in just the last year. As far as suitability for life goes, about the best we can say at the moment is that some of those planets are small enough that they're not massive gas giants like Jupiter or Saturn. They are smaller, rockier worlds. Like ours. And some of those like-ours planets are also at the right distance from their own sun that it's possible they could have liquid water. They're not quite planets where life is likely, but they are planets where life isn't impossible.
Within the rather restricted neighborhood of stars that are closer to Earth than 50 light years, we know of about a dozen planets that fall in the "life isn't impossible" set. This number is changing rapidly. It's bound to increase by an order of magnitude, or two, in the next few years. What's special about these nearby worlds, other than just being at the same table as the Cool Planet? These guys are close enough that radio waves from Earth have already reached them. We've broadcast a big "We Are Here!" to any cosmic Horton who happens to be listening. So ... is anyone listening?
Two years after Cocconi and Morrison, astronomer Frank Drake codified the the considerations about what it takes to make an alien civilization into what's become known as the Drake Equation.
N = R * P * S * L * I * C * T
If you take the
Rate of star formation in the galaxy, multiply by the fraction of stars that have
Planets, then by the percentage of planets that that could possibly
Support life, then by the subset that actually develops
Life, then go on to the portion where
Intelligent life evolves, then look at only those places where a technological
Civilization arises, and finally limit the value by the
Time such a civilization persists, you get the
Number of civilizations out there that we might talk to. (Apologies for not using the more common notation, Drake Equation fans. I got way tired of doing subscripts.)
You can plug a lot of different values into an equation like this. Drake's original guesstimates pumped out a range of 1,000 to 100,000,000 civilizations in our galaxy. Yes, that's quite a range. Drake's made a sheer guess that between 20 percent and 50 percent of all stars had planets. As it turns out, that's probably on the low end. On the other hand, Drake looked at our solar system and figured that if a star had planets, then at least one of those planets would be in the "not impossible for life" zone. That turns out to be not so true. There are a lot of stars out there with systems that are profoundly different from ours. In any case, reasonable people using reasonable values for all the terms in the equation have since gotten numbers between 0 (making us quite an anomaly) and 35 million. Split the difference, and there would be 17 million civilizations out there.
That's the kind of number that should make Cocconi and Morrison happy. If there are 17 million planets full of aliens with their pointy ears planted next to receivers, it does seem kind of likely that someone might have their mighty listen-o-tron pointed our way. An effort at listening back definitely seems worthwhile.
Only ... static. Hmm. More static. Wait! Wow! Oh, sorry. Static.
We might have expected it. Ten years before Cocconi and Morrison published their paper, Emil Konopinski, Edward Teller, Herbert York, and Enrico Fermi sat down to have lunch. We don't know what they ate. Probably fish. Anyway, with that much brainpower around the table, the conversation whizzed through a number of topics, including the possibility of space travel.
Eventually, Fermi asked the question that has been flummoxing folks ever since.
"Where are they?" — Enrico Fermi
As in, if intelligent life is possible—and we have what's generally considered decent evidence that it is—and there are so many opportunities for such life to develop in our exceedingly big galaxy .... then where are all the flying saucers?
A lot of people have tried to answer Fermi, and a lot of those answers come back to the same thing: space. Space has one hell of a big trick up its sleeve. The trick that it's big. You can research this in the definitive source.
"Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." ― Douglas Adams, The Hitchhiker's Guide to the Galaxy
Considering the nasty speed limit imposed by relativity—Einstein! (fist shake)—the distance between stars does make a pretty formidable barrier. Even if there are 17 million civilizations out there, they would be facing a considerable amount of elbow and/or tentacle room in a galaxy that's roughly 180,000 light years across. That's 6,000 square light years per civ. No need to run into the neighbors.
Don't worry, so am I.
Only, no. Bzzzz. Bad answer. Just because travel between stars is dauntingly long, doesn't make it impossible. It makes it ... long. As in
T back in Drake's equation. If we're forced to contemplate that space is big, we need to also consider that time is long. Deep Time is often more difficult for people to contemplate than Deep Space. After all, you can focus a telescope on a distant galaxy and say, "yup, that's far, far away." That it's also long, long ago is less obvious. Trust me: space may be big, but time is just as big.
The truth is that just one (1) civilization is all that's required to litter the universe with their stuff, so long as they have enough time. You don't even have to be better than humanity to pull off this trick. Even if our technology for traveling between the stars never advanced from its current slug-like pace, given a few million years, we could drop a probe into every. single. star system. in. the. galaxy. I propose we shape them like the markers in a game of Risk.
Actually, it needn't take even that long. So-called "von Neumann probes," based on physicist John von Neumann's idea for self-replicating machines, might spread across the galaxy in a few hundred thousand years.
There's no specific reason to think that humans are particularly early risers in the cosmic scheme. The sun and the Earth aren't especially old when compared with other systems. Far from it. We're on the youngish end. And intelligent life didn't actually crawl right up out of the muck in this place. We took a damn long and leisurely stroll to get ourselves evolved over the last 3 billion years. Over the course of that stroll, Earth had several incidents that dropped whole ecosystems into the waste bin. Things with names like The Great Dying. Had these big extinction events not occurred, some completely different branch of animalkind might have been the first to appreciate the handiness of prepackaged wet wipes while mammals weren't even on the drawing board.
Surely, somewhere out there among all the potentials, there were some planets—maybe many planets—where life got going sooner, and where the path to unreasonably large craniums was smoother. They should have had a head start on us measured in millions, if not billions, of years.
Which brings us right back to lunch with Enrico. If life is even a fraction as common as we would expect, and if it's had so long to develop, we ought to be stumbling over alien artifacts. They wouldn't be a mystery visible only to guys with tall hair doing late night duty on the History Channel, they would be everywhere. Maybe we wouldn't be sharing latte with the aliens themselves. Maybe no one among the 17 million candidates was ever up for the long, long, long ride to see wassup at the solar system next door. But probes. There should be probes. You shouldn't be able to walk to school without stepping over some civilization's equivalent of a gold record and a diagram of them waving an appendage. Nekkid.
Only ... we don't. So why not? Well, there are a lot of different thoughts about that. There's a cluster of theories around the idea that we are astoundingly unique. I call this category "Humans: Humility R Not Us." There's another set of theories based on the premise that civilizations simply don't last long before they blow themselves up, par-broil their home planet, or just get very tired. I think of these as the "Don't Make Any Long Plans" theories. There's another group that's even more fun that falls under the sobriquet "Baby in the Woods with Wolves." As in: if all babies are born in the woods, and there are wolves in the woods, noisy babies are quickly eaten and only quiet babies survive. (Warning: you are one tiny part of a quite noisy baby.) That last one is part of a broader subset of theories that proposes that there are many civilizations out there capable of listening, but for various reasons no one is talking. I call this whole group of theories "Sad."
As it happens, I have my own theory. Which is why I brought you here today. That's right, sucker, everything up til now has been preamble.
My theory is that we don't notice any aliens, because aliens don't exist. That's okay though, because neither do we.
(For the next part, tune in next week. Same Earth Time. Same Earth Channel.)