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Tuesday, March 05, 2013

RANDOM THOUGHTS #130: LIFE ON OTHER PLANETS

Steve Cole writes:
    
Recent scientific work has found lots and lots of planets, at least 2300 of them. The method we use to detect them cannot detect 80% of stars with planets (because the orbital plane is at the wrong angle), so it's very likely that almost every star out there has a nice set of about ten of them. (In the case of stars with Hot Jupiters, the big planet spiraling in may have destroyed or ejected any planets that were originally closer.) We can only see the big planets so every planet we can see probably has three or four little brothers (at least).
 
How would we know if any planet has life? Well, by going there, I guess. Put that one down on the "to do" list. Maybe we could detect an alien civilization by detecting their television and radio signals? Maybe, but as our own technology gets better, the amount of power used by radio and television drops like a rock, so you may have at most a 100-year window in the history of a civilized planet where they generate enough radio waves to be noticed.
    
Some point to that old equation that makes 10 assumptions and ends up speculating that every civilization destroyed itself in a nuclear war. I don't think there's any evidence to support the inevitable self-destruction of a sapient species. To be blunt, the ONLY evidence we have (ourselves) is that it does NOT happen, at least not in the nuclear war that most think of. I'm sure it did happen, some percentage of the time out there in the galaxy, but our own history proves that sane heads prevail and that systems designed to prevent accidental war have a high degree of working as advertised. (All of those "nuclear war almost started by accident" stories, if you really read them, show that it was never really a close thing. The Cuban Missile Crisis and Reagan's Pershing missiles just prove that saner heads prevail and deals get made.) You must also remember that the original self-destruct theory was not a scientific theory about life on planets but a political statement about about nuclear disarmament.

We might consider asteroid impact as the inevitable end of any civilization, but seriously, an extinction level event is pretty rare (one in 63 million years and counting!) and if you consider that we'll surely have a perfect asteroid defense in another century, the window of vulnerability is pretty small (maybe seven thousand years from pyramids to a bulletproof planet) and almost closed. Even then, we've had ELEs five times in 4.7 billion years and better species appeared after each one, so even if we get smacked by a big rock, give it 63 million years before the cockroaches or the lobsters or the racoons have space-based communications.

The real danger (now that the Mayans are out of the game) may be overpopulation. Just my guess, but I think even that is self-correcting as the environment will eventually go bonky and cut the population by some huge percentage (disease, famine, drought, collapse of the ozone, zombies, or something). After that, the world heals and leaves the sub-billion-human population with all of the technology and the knowledge that limitless baby production is not a good plan.
  
How many planets have life? By our own evidence, around 12.5% (and maybe 25% or more if we count that moon of some gas giant with an ocean full of speculative fish, and definitely more if we assume Mars had microbial or better life at some point). The actual number in the broader universe is probably lower, but even 1% of a whole bunch is a whole bunch. Kepler has found 2300 planets in the neighborhood, and give orbital plane angles you're probably talking 10,000 or more just around here.
  
How many of those planets produced sapient life? Well, the evidence we have is arguably 50-50 (if only because you cannot prove that the Martians ever got that far, even if they had a billion years to give it the old evolutionary try).
    
I suspect that a thousand or so years in our future we may reach the "ascended beings that just no longer care about the mortal plane of existence" level.