What is life? That was the first question at my last festival event of the weekend--which was sold out, like every other event I attended. However you measure it, the festival looked like a hit: packed halls, riveting speakers, belly laughs, probing questions, subtle answers, and diverse crowds of audience members blocking the sidewalks afterward as they continued the debates.
Anyway, what is life? If you believe Steven Benner, a synthetic biologist, it’s a self-sustaining chemical system capable of Darwinian evolution. Paul Davies, a theoretical physicist and astrobiologist, thinks it’s all about information reproduction and processing: “No system other then life or a product of life processes complex information,” he says. And astrobiologist Margaret Turnbull is impatient with the very question. “As soon as we make a definition, it’s only a matter of time before it’s proved limited. I would much rather get out there and look for it and see what it’s like,” she says.
How will she do that? One way to hunt down Earthlike planets is to watch dense fields of stars for transits: shadows of planets passing across the stars’ faces. Another is to use starlight suppression. Stars are so bright that we can’t see planets in the dazzle, so astronomers could fly huge, Hubblelike telescopes accompanied a little ways off (80,000 kilometers) by “starshades,”vast plastic sheets to block the star’s light.
So once they find life, what will it look like? Will it be water-based, or will it rely on some other molecule that’s abundant in its home--methane, say, or ammonia? Will it have 4-letter DNA like us? Twelve-letter DNA, as Benner described having synthesized? Will it, perhaps, store its information not in a linear double helix as we do, but in clay sheets? Will it drink up sunlight? Will it gobble methane? Will it look for us?
The scientists couldn’t say, but they were all eager to find out.