http://en.wikipedia.org/wiki/File:SETIcon_II_Artwork_with_Drake_Equation_by_Danielle_Futselaar.jpg

SETIcon II Artwork, featuring the Drake Equation, by Danielle Futselaar

 

I’m a sucker for a good science fiction story. I’ll admit that straight up. The thing that gets me, though, is how many people scoff at this. There are whole industries built around poking fun at nerds and how they always have their heads in the clouds.

This confuses me, because we have whole industries built around the fruits of such labours as only the nerds and the geeks can provide. I am told with a great deal of certainty that prior to the 1960’s, that landing on the moon was synonymous with doing the impossible. There is still a saying, “shoot for the moon”, which reflects that, only now it means more “aim high” than “dream up something you can’t do, so you’ll do something amazing trying”.

And why, really, when I get down to it, do I remain confused? Because of one man. Well, lots of men (and women), but one man in particular: Frank Drake. He took, if you are not familiar with this probablistic equation, all of the variables relevant to working out just how likely there are to be active, communicating civilisations out there within our galaxy, and expressed them in a relatively easy to understand format that is pretty much self-explanatory.

The Drake Equation was born.

Copied directly from Wikipedia (linked above), The Drake equation is:

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

where:

N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone);

and

R* = the average number of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space

Now, some of these values are well-known – N, for example, is at least 1 (since, well, here we are!) – but the rest of them required populating with values that, when the equation was written, were theoretical at best, and wild stabs in the dark at worst. Now, though, we know quite a bit more.

For example, extra-solar planets – planets around stars other than the sun – have been discovered to be not only common, but extremely common. It seems likely that every sun will have planets, and that of these, every sun will have a planet of the right composition and roughly the right sort of place that life may arise.

So, where is everyone? With estimates of between 1000 and 100,000,000 civilisations bouncing around our galaxy alone, where is everyone?

Well, good question – and this is where the Drake Equation is a cause for deep introspection, because even at sub-light speeds, one sufficiently advanced race can colonize the galaxy in under a million years.

Reading one book which is a firm favourite of mine, called simply Extraterrestrial Civilizations by Isaac Asimov, an updated look at the equation suggests over half a million technological races exist… but why aren’t they here?

Now, lots of people claim to have been abducted, but I don’t find any of those claims particularly reliable. I find it likely that an intelligent species would take samples, tag, and release back into the wild (after all, that’s exactly what we do), but I’m not sure if such visitors would need to. So maybe what happens is that sufficiently advanced races cease to see physical travel as necessary, and communicate purely in ideas, whilst their corporeal forms essentially stay home?

I hope so, because the alternative that we’re alone in the universe is, quite frankly, impossible, leaving the only alternatives either that intelligent life kills itself (bad news for us) or just isn’t very chatty (in which case, we’ve got a long haul into post-sentience which is epitomised by the hockey-stick of the growing pace of change…)

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