Sunday, June 15, 2014

Scary extra-solar planets, are the stars right?

So, for a long time I didn't really get H.P.Lovecraft, the author of a bunch of books and short stories set in a mythos that has been used by many authors since.  Even if you've never read anything by him, I hope you've at least heard the name Cthulhu at some point.  The problem is that the sense of cosmic dread that he sought to convey in his works didn't really work with me.  I've grown up knowing of the vast voids between the stars.  I've always, for as long as I've known about history, known that history began long before mankind was around and that the time between the first campfire and the present day is just a small slice of all the time that came before.  All this familiarity means that I can't really appreciate his works the way that maybe people at the time could, familiarity breeds contempt.

The first time I really got a taste of real cosmic dread was when I ran into the concept of Boltzman brain's.  To explain it simply, if the universe goes into a heat death then across the infinite future all the consciousnesses that arise through random interactions of matter will drastically outnumber the consciousnesses that arise due to things like evolving in a sane environment.  There's a lot of reasoning behind this, and I could go into it but not until I've done some posts about understanding entropy.  Thankfully the last I heard the consensus was that the universe will end in some other way so we don't have to worry about Boltzman brains.

The other thing that has given me cosmic shivers, though, is the idea of the Great Filter.  A long time ago Dr. Frank Drake tried to figure out how many alien civilizations we should expect to find in our galaxy, and developed an equation to help him do that.  You just multiply the number of stars being created each year, by the number of potentially life supporting planets per star, by what fraction of those actually develop life, by the faction of those that get intelligent life, by the fraction of those who ever develop the technology to broadcast signals into space, by the length of time they're broadcasting before stopping or being destroyed somehow.

We don't have a good idea of the exact values for many of those, estimates vary by orders of magnitudes.  But we do know that there are lots and lost of stars in our galaxy, and we know that we haven't seen a single signal that looks like an alien.  It might just be phenomenal bad luck in our timing, but that tends to suggest that the end result of the equation is at least less than one, which means that some of those intermediate terms are very small.

But which of those terms is the small one?  If very few stars have planets or few of those planets are of the sort that can support life then fine, we're special and unique snowflakes and we can go confidently into the empty universe and do fun things with it.  But it might also be that the really small term is the last one, and most civilizations quickly have nuclear wars or out of control nano-replicators or lose control of an artificial black hole or something.  That would be Very Bad for either ourselves or our descendants.

This is why the recent discovery of lots and lots of extra-solar planets fills me with a sort of cosmic horror, in addition to excitement at all the potential cool new places to visit.  Wikipedia's list of potentially habitable extra-solar planets keeps getting longer and the longer it gets the better we know that the first few potential hurdles Drake saw can't be all that high.  Maybe another of the hurdles we've already passed, developing intelligent life for instance, is the tough one, but maybe it's one in front of us as well.

Of course, you shouldn't worry all that much.  Maybe the first civilization that evolves ends up colonizing the galaxy and no intelligent life evolves naturally after that.  All of this rests on anthropic reasoning and as far as I can tell everyone is really bad at doing that sensibly.

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