Friday, December 3, 2010

Life Made of Arsenic Equals More Probable Aliens

NASA announces discovery of arsenic-based life in a California lake.

Here's the super-quick summary:
Until pretty much just now, it was understood that all life was built on six elements: oxygen, hydrogen, carbon, nitrogen, sulfur, and phosphorous.
This newly recognized bacteria replaces phosphorous with arsenic.

This is Big News.

(Note that the fact that the scientists' experiments are responsible for the arsenic bacteria doesn't change the fact that life is now factually possible with arsenic instead of phosphorous.)

NASA originally set the stage for this by announcing a press conference that would "impact the search for evidence of extraterrestrial life." What does arsenic-based life on Earth have to do with alien life? Well, if life can exist on Earth with a different basic chemistry, there's no reason to believe it is not possible that life could exist on other worlds with radically different chemistries. No longer is an alien world required to have sufficient O, H, C, N, S or P for life. It could have O, H, C, N, S, As. It could be theoretically be built with Helium, or Selenium, or Silicon, or Neon. This vastly, vastly increases the number of places in the universe that life could exist.

Personally, I (among others) had no doubt that there was extraterrestrial life in the universe prior to this announcement. This discovery only reinforces that. To state my own position more clearly, it's not a matter of whether life exists elsewhere, nor is this a matter of belief; it is all but utterly ridiculous to think otherwise based on the sheer numbers. The only question is "will we ever be able to communicate with the other life?"

There are estimated to be as many as 170 billion or more galaxies in the universe. Galaxies contain billions of stars on average. Even if life is so rare that intelligent life only occurs once in any given galaxy over the entire course of time, that still means 170 billion civilizations at some point or other exist. And that's an astronomically low estimate.

The Fermi paradox questions how, if there are so many life forms, we haven't heard from any. That Wikipedia article gives plenty of the counterarguments, so I won't get way into it, except to say that the key factor, from my point of view, is that aliens are going to be so alien that is is unlikely that we are listening in the right way at the right time in the right spot to identify them - or vice versa. Don't forget that only a little more than 100 years ago human beings sent no recognizable signs of our intelligent life into space, so only civilizations 100 light years away can see us yet. The galaxy is 1,000 light years thick - and 100,000 light years across. (So less than 1%of the galaxy is potentially aware of us.) Don't forget, also, that we can only detect distant civilizations if they're pretty advanced. If there are alien lions and tigers and bears living on a planet only a couple star systems over, we'll have no idea whatsoever for quite a while - but it would still be history-shattering to discover that such life existed, wouldn't it? Heck, it would be pretty much The Most Important Discovery In History to discover with certainty that bacteria-sized simple life developed independently on Mars, or Europa, or Titan.

Keep in mind also that we've been discovering exoplanets at an increasing rate only in the last two decades. We're up to about 400.

That's about all I've got to say at the moment.

(My apologies to those schooled in these matters, for whom little of this is particarly revelatory and is probably better analyzed on more specialized blogs. I think this news is so exciting that I wanted to share it with any of our readers who are not familiar or have not heard about it.)

No comments: