Is Extraterrestrial Life More a Dream Than a Real Possibility?

Illustration for article titled Is Extraterrestrial Life More a Dream Than a Real Possibility?

There is no getting around the fact that a lot of people would be very excited if extraterrestrial life existed. But while plenty of scientists are working hard to find it, others aren't as convinced—and a team of Princeton physicists has gone as far as publishing an academic article explaining exactly why they think we're all living in a fantasy land.


In the Proceedings of the National Academy of Sciences Edwin Turner and David Spiegel, two astrophysicists from Princeton, analyze what is known about the likelihood of life on other planets using Bayesian analysis. They weigh up how many of our existing scientific conclusions about life on other planets stem from actual, real data, and how many come from the prior assumptions of scientists.

Their analysis points out that our expectations of life cropping up on other planets tend to rest on the assumption that it is only possible on other planets under the same conditions that allowed life to flourish on Earth. Sadly, our current knowledge of other planets in the universe tends to suggest Earth is a "cosmic aberration where life took shape unusually fast".

That suggests that we're all being hopelessly fantastical in assuming that other life must exist. In Turner's words, speaking to R&D Magazine:

"Fossil evidence suggests that life began very early in Earth's history and that has led people to determine that life might be quite common in the universe because it happened so quickly here, but the knowledge about life on Earth simply doesn't reveal much about the actual probability of life on other planets...

"Information about that probability comes largely from the assumptions scientists have going in, and some of the most optimistic conclusions have been based almost entirely on those assumptions..

"If scientists start out assuming that the chances of life existing on another planet as it does on Earth are large, then their results will be presented in a way that supports that likelihood. Our work is not a judgment, but an analysis of existing data that suggests the debate about the existence of life on other planets is framed largely by the prior assumptions of the participants."

Way to run the party, guys. Still, there is also some evidence we should remain hopeful. [PNAS via R&D Magazine]


Image by NASA



While I disagree that life may not be common in the universe, I do think "intelligent" life may be extremely rare.

We are going on the assumption that life started very early in Earth's development that life must be common...and I view this as a valid argument. There is nothing special about our solar system. It's composition is nothing out of the ordinary, our star is a typical long period yellow dwarf, and the only thing we have going for us our planet orbits in a position that allows for liquid water.

We won't know if life actually IS common until we find it somewhere else are can compare notes (I'd LOVE for a Europa mission to get moving — probably the best chance of finding other life), but from what we've observed, the system to get life started isn't very difficult—-just lengthy.

Now, as for intelligent was vanquished and restarted on Earth quite a few times. In the 4.6 billion years of Earth's existence, only one intelligent species has ever appeared: Hominids. And of that, the subset of homo-sapiens are the only ones that became intelligent enough to manipulate our environment. This suggests that either:

a) Intelligence is a fluke—perhaps even an unwanted flaw.

b) Intelligence is the pinnacle of any life's evolution (life keeps trying different combinations until it finds the right recipe for intelligence), but it takes an extremely long time to achieve.