A very thoughtful reader post

Reader "Ernie" wrote a very thoughtful post to my last entry ( see http://tinyurl.com/54d7u )

Thank you for your excellent post, Ernie.

Yes, the requirements for life to get started are rigorous. Astronomer Frank Drake produced a famous equation (the eponymous "Drake Equation") that tries to make reasonable, educated guesses about how common life is. His equation looks scary, but actually is just assigning best-guess numbers to things like how many stars there are, what percentage of stars have planets, what percentage of planets have conditions favorable for life, how many actually produce life, how many produce intelligent life, etc.

The early math guesstimated that there's a fair amount of life in the broadest sense (including simple microbes), a much smaller subset of intelligent life, and at best maybe 10 advanced, technological civilizations sharing our galaxy. Of course, the galaxy is so large that finding them will be very hard; something like finding 10 particular grains of sand scattered somewhere among all the beaches in all the world.

Some estimates place the numbers higher, others (including the above Wikipedia article) lower.

In any case, all the estimates were based on a belief that only about half of all stars will have planets to start with.

But now, we're finding that planets are actually common. Planets may even be the Universe's default state for star systems.

I can remember science texts and articles (not all that long ago) showing star formation as a neat symmetric infall to a cloudy, glowing core; a little rotation creating a lovely whirlpool effect.

But nature isn't that tidy. Star systems aren't born in a neat symmetric infall, but rather in the slow-motion teeming chaos of a condensing nebula, compressed by shockwaves from distant novas and on its way to gravitational collapse. You've seen pictures of that kind of nebula; Hubble has captured many, like this:



It's beautiful, but there's nothing neat about it. It's all swirls and eddies, columns and clouds, dense knots and tenuous veils. In short: A gorgeous, seething mess.

Messy enough, in fact, so that after the stars form, there'll almost always be stuff left over: Planets. And that's what changes one of the Drake Equation's foundation assumptions.

It means that the pool of potential life-supporting planets is much, much larger than anyone previously thought.

That doesn't make Earth any less special, at least not to those of us who live here. It takes nothing away from us or our situation, which remains as before.

But just as travel abroad lets you see your own culture and life in a new way, finding other life forms (advanced or not) in the universe would tell us a lot about ourselves.

TS Eliot said "We shall not cease from exploration and the end of all our exploring will be to arrive where we started and know the place for the first time."

With the search for extraterrestrial life, it's not just a place we're coming to know, but our very selves.