The Continuing Search for Intelligent Life

With the elections only a two days away, I started to think about intelligent life elsewhere (if only because I was wondering about its presence locally).  The discovery last month of a planet in the "inhabitable zone" of the Gliese 581 red dwarf star system provided the scientific community (and the rest of us) with some further evidence that we are not necessarily the only location for life.  This new planet, discovered using the W. M. Keck Observatory in Hawaii, is three times the mass of Earth and believed to have a rocky surface that is tidally locked to the star, meaning that one side is always facing the star.

If you recall the Drake Equation, it estimates the likelihood of finding intelligent life elsewhere in the Milky Way.  One of these factors ("L" from below) is the length of time such civilizations release detectable signals into space.

The equation calculates "L" at about 10,000 years.  Astronomer Carl Sagan had his doubts about a civilization reaching this point and not destroying itself, whereas Astrobiologist David Grinspoon was somewhat more optimistic.  In an Astrobiology Magazine article, Grinspoon states:

AM: You say that because life and its biosphere are so intertwined, it may not be possible to have an individual definition for "life."

DG: I suspect that life can only survive on a planet for billions of years if it has become deeply embedded in the geochemical, physical, and climatic cycles of that planet in a way that stabilizes the environment. If this is the case, life will not be found in isolated, discontinuous pockets on a mostly dead world, but will always, as on Earth, permeate its planet.

I think of life not as something that happens on a planet, but as something that happens to a planet. Life is a quality that the planet takes on. And it might be something that sticks and lasts through huge environmental and physical changes, as it has on Earth.

AM: You also state that humans may be the biosphere's way of gaining consciousness and self awareness, and that we are at the very beginning of this evolution.

DG: We don't know how hard it is for a planet to evolve a biosphere, or to become a "living world," but once it gets to that state, I would bet that such biospheres survive for billions of years. So they would last for much of the lifetime of their planet's parent star, and occasionally longer.

Stars have a limited life span. Stars like our sun, for instance, burn out after 10 billion years. After that, life on any habitable planets orbiting that star will go extinct. So if you want to outlive your star of birth, you will need to become complex and sentient and comfortable with space travel. Your biosphere must wake up and consciously choose survival, as Earth's is now attempting to do through the clumsy human experiment.

I hope we are smart enough to figure all of this out so we can live long and prosper.  In the meantime, we will  keep up the search for intelligence at home and abroad.