Monday, June 22, 2009

Extraterrestrial life: Immanuel Kant, meet Frank Drake and Carl Sagan

From "Looking for planets like ours", a review by Michael Brown of Alan Boss's The Crowded Universe: The Search for Living Planets:
Even if the Kepler and COROT missions do find an abundance of planets, the Kantian revolution will not be complete. The new planets might be exactly the same size as Earth and orbit their stars at the same distance, and although an astronomer might be willing to call such a thing Earth-like, most people will look for more. Does it have liquid water? Does it have a recognizable atmosphere? And, inevitably, could it — does it — support life?

Finding the answers to these questions will take decades. Kepler and COROT are merely steps along the way. In the meantime, we can take solace from Kant: "I am of the opinion that it is not particularly necessary to assert that all planets must be inhabited. However, at the same time it would be absurd to deny this claim with respect to all or even to most of them."

It took nearly 250 years to prove him mostly right the first time. With a little luck and perseverance — and, as Boss shows, a lot of work by astronomers around the world — the final step may just come a little faster.
I wonder whether Kant would regard the discovery that bacteria had once lived on Mars or might live elsewhere - if it is made - as evidence for his position.

See also:

Alfred Russel Wallace on why Mars is not habitable

See also: Boldly go, but why, exactly?Extraterrestrials:

Several million UFOs later - the state of the question

Younger astronomers less likely to believe than older ones?

So what if fossil bacteria are found on Mars? Polls show many Americans expect Star Trek!

Some scientists hope that the aliens are NOT out there!

Increase in UFO sitings in Canada - what's behind that?