Tuesday, January 01, 2013

Invaders from Space!

One of the best things ever posted on the Internet is this bit posted by one Nick Bostrom.  In it he posits that we may be alone in the whole universe based upon what he calls 'The Great Filter', which is basically a series of high hurdles that molecules on some rock in space most overcome in order to advance to the point of being able to launch a rocket into space:
You start with billions and billions of potential germination points for life, and you end up with a sum total of zero extraterrestrial civilizations that we can observe. The Great Filter must therefore be sufficiently powerful--which is to say, passing the critical points must be sufficiently improbable--that even with many billions of rolls of the dice, one ends up with nothing: no aliens, no spacecraft, no signals. At least, none that we can detect in our neck of the woods.
In the book Sphere, Michael Crichton's character Harry (played by Samuel L. Jackson in the dreadful movie adaptation) also voices extreme skepticism, pointing out that the Drake equation used by alien cheerleaders could be rendered moot if any of their assumptions weren't greater than zero:
“What it means,” Harry Adams said, “is that the probability, p, that intelligent life will evolve in any star system is a function of the probability that the star will have planets, the number of habitable planets, the probability that simple life will evolve on a habitable planet, the probability that intelligent life will evolve from simple life, and the probability that intelligent life will attempt interstellar communication within five billion years. That’s all the equation says.”
...
“But the point is that we have no facts,” Harry said. “We must guess at every single one of these probabilities. And it’s quite easy to guess one way, as Ted does, and conclude there are probably thousands of intelligent civilizations. It’s equally easy to guess, as I do, that there is probably only one civilization. Ours.”
I bring this up as Glenn Reynolds has an affinity for posting alien invasion/contact stuff, the latest linking to an article by Gregg Easterbrook that argues that any aliens would probably tend to be aggressive just due to natural selection:
James Trefil, of George Mason University, has cautioned that if evolution functions approximately the same way on other worlds that it has functioned here -- conferring survival upon the fittest -- advanced extraterrestrials might still be aggressive, territorial, and quick to reach for the sword. In that case, counting on poor alien marksmanship might not be prudent.
This is cherry picking on his part though.  At first I had the article pegged as a rehash of the Nick Bostrom article that I cited earlier, but it turns out to be the other way around as the  Easterbrook piece was written 20 years (1988) before the Bostrom piece (2008), and only a year after Sphere wherein Crichton's character derides the same Drake equation that is poked at in the Easterbrook article.  All come to the same conclusion: interstellar life is exceedingly rare, perhaps to the point that it only exists here.

Maybe it's not that bad though.  What's rarely brought up in these articles is the matter of life as it is on Earth.  For how long was the Earth ruled over by creatures that couldn't even rub two sticks together?  It can also be argued that were it not for quirks of geography and culture (and race?) that formed Western European thought, that mankind would still be living under some sort of backwards Northeast Asian / Ottoman Empire style feudalism, possibly in perpetuity.  Tribes in places like Papau New Guinea, where people can practically sit under a tree and have it feed them, can scarcely be bothered to build a boat to go to a nearby island, let alone build a rocket the moon.

And those are the easy barriers to overcome.  Researchers have said that one reason that New World tribes were held back in being able to advance was their lack of a draft animal along the lines of an ox or horse.  What if a planet never had those?  Maybe didn't have fossil fuels?  Or perhaps didn't have any minerals of any worth close to the surface?  The more barriers thrown up, the more zeros that come after the decimal point for cheerleaders of advanced alien civilizations.

Life is indeed rare, but maybe not to the extent that skeptics would have.  But what of intelligent life?
That's certainly nearly non-existent.

2 comments:

Marty Plumbo said...

In an infinite universe, with potentially infinite dimensions, do probabilities as we know them even exist?

Evil Sandmich said...

John Derbyshire at one point in time had spoken about how man has a decent idea of the size, age, and probable lifetime of the universe; like much of his stuff, it was all very depressing.

I will admit though that when I look out at the stars I tend to imagine to myself that there are infinite possibilities and that logically there must exist someone somewhere out there has solved all the 'big things' that nag mankind in it's day-to-day existence (and that ergo, such a thing is possible).

Besides that though, seeing images and science that have come back from places like Mars, Jupiter, and Saturn I am puzzled why mankind would be satiated with existence solely on earth. Indeed someone interviewed for the article cited by Reynolds notes that at some point in the not too distant future it might be feasible for man to build spacecraft that would enable him to colonize the galaxy in 50 million years. This is a long time to be sure, but a flash in the pan compared to the age of just about anything that isn't directly related to man.

I found that fascinating, that man could, maybe not collectively, but totally, know nearly everything about the galaxy in such a short amount of time. However at the same time, with such a thing being so readily feasible to any civilization that is even just somewhat more advanced than our own, where are all the extraterrestrial pioneers? It seems we should be practically tripping over evidence of extraterrestrials given some of the probability numbers bantered about.