Why we have yet to find extraterrestrial life

Although there is plenty of habitable real estate out there, "habitable" is not the same as "inhabited," says Arizona State University Regents Professor and noted cosmologist Paul Davies. Because nobody knows how non-life transitioned to life on Earth, it is impossible to estimate the odds of it springing forth elsewhere in the universe.

Davies presented his findings on Feb. 16 at the annual meeting of the American Association for the Advancement of Science in Austin, Texas.

"During my career, opinion has shifted from life's origin being a bizarre fluke unique in the universe ('almost a miracle' in the words of Francis Crick), to the belief that the universe is teeming with life ('a cosmic imperative' in the words of Christian de Duve)," Davies said. "How can we settle the matter? For several decades astronomers have been sweeping the skies with radio telescopes hoping to stumble across a message from ET. So far they have been met by an 'eerie silence.'"

"Meanwhile, astrobiologists have considered how signatures of microbial life might be detectable in the solar system or in the atmospheres of extra-solar planets," Davies added. "If life really does form readily in Earth-like conditions, it should have started many times right here on Earth, so we should look for a 'shadow biosphere' of life, but not as we know it, under our very noses.'"

Davies is a cosmologist, theoretical physicist, astrobiologist and best-selling author. His latest book 'The Eerie Silence" is a celebration and critique of the search for cosmic company.

Davies is a member of the Breakthrough Listen Committee and formerly chaired the SETI Post-Detection Task group of the International Academy of Astronautics. He was the first person to champion the idea that life on Earth may have originated on Mars and transferred here in impact ejecta. Davies is director of the Beyond Center at ASU that researches how life began in terms of the organization of information in complex networks -- the software of life. His forthcoming book "The Demon in the Machine," is a penetrating look at the power of information to explain the physics of living matter.

Davies will detail his research in the presentation, "The search for life beyond Earth," as part of the "Is There a Future for Humanity in Space?" session, 10 a.m. CT on Feb. 17.