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From Space Dust to Spacefarers
14 August 2007 (All day)
Dirt that acts like DNA? Using computer simulations, a team of physicists has shown that it's possible for dustlike particles to divide, replicate, and even evolve. The findings hint at one way that life could have gotten started on Earth, and even the incredible although remote possibility that life--and perhaps intelligence--could exist among the interstellar clouds of outer space.
Conventional wisdom says life in the universe requires carbon and liquid water. With these two simple necessities, life has crept into just about every nook and cranny on Earth, from the scalding waters of deep ocean vents to the underside of Antarctica's icy rocks. As a consequence, scientists looking for extraterrestrial life have based all of their searches and instruments on the existence of carbon and--on Mars, for example--on minerals that only could have formed in the presence of water.
Now comes the prospect that life might be able to evolve in an astoundingly simple fashion. Reporting online in today's issue of the New Journal of Physics, a team from Russia, Germany, and Australia details how computer simulations of molecular dynamics can produce conditions under which evolution appears to begin spontaneously. In their simulations, free-floating molecules begin organizing into a helixlike structure resembling DNA, and as time passes, more stable molecular arrangements begin replacing less-stable versions. The process proceeds, the authors say, because an electrical property called polarization tends to organize the particles and reduce chaos, much like tuning a radio to the proper frequency can produce clear audio from the static. The findings are particularly intriguing, they say, because molecular clouds are common across the universe, such as in vast zones of dust among the stars of the Milky Way.
The research is sound and it suggests "a mechanism whereby organic matter could assemble faster than in previous models," says plasma physicist Mark Koepke of West Virginia University in Morgantown. The shorter time could mean a greater probability that conventional life exists elsewhere in the universe, he says.
However, astrobiologist Margaret Turnbull of the Space Telescope Science Institute in Baltimore, Maryland, cautions against underestimating the critical role that water plays in life. Water is "so fabulous for life" because it shields organic molecules "from the electrical charges that would normally drive them apart." Although the researchers may indeed have found another medium within which complex molecules can interact in sophisticated ways, Turnbull says, it remains to be seen whether the right conditions exist in space for these structures to become "complex enough to seed life on young planets."