AAAS: 'One hundred billion trillion' planets where alien life could flourish

By Richard Alleyne, Science Correspondent in Chicago

Dr Alan Boss, of the Carnegie Institution in Washington DC, said there could be as many Earths as there are stars in the universe Photo: REUTERS

Life on Earth used to be thought of as a freak accident that only happened once.

But scientists are now coming to the conclusion that the universe is teeming with living organisms.

The change in thinking has come about because of the new belief there are an abundant number of habitable planets like Earth.

Alan Boss, of the Carnegie Institution in Washington DC, said there could be as many Earths as there are stars in the universe - one hundred billion trillion.

Because of this, he believes it is "inevitable" that life must have flourished elsewhere over the billions of years the universe has existed.

"If you have a habitable world and let it evolve for a few billion years then inevitably some sort of life will form on it," said Dr Boss.

"It is sort of running an experiment in your refrigerator - turn it off and something will grow in there.

"It would be impossible to stop life growing on these habitable planets."

He believes his views will be proved by NASA's Kepler outer space-based telescope, which takes off in the next three weeks with a mission to track down Earth-like habitable planets.

Within four years Dr Boss, who was speaking at the American Association for the Advancement of Science meeting, believes it will have found one in our galaxy and that will prove his theories about their abundance.

He then would like researchers to build even bigger telescopes and send out an unmanned spacecraft to take photographs of the distant planet that could be up to 30 light years away. It would, however, take at least 2,000 years to report back.

Dr Boss said: "We already know enough now to say that the universe is probably loaded with terrestrial planets similar to the Earth," he says.

"We should expect that there are going to be many planets which are habitable, so probably some are going to be inhabited as well."

Whether the life we find is intelligent is, however, less than inevitable.

"Intelligent life seems to be fleeting," he said. "In terms of the universe it only exists for a fraction of time."

He said it would be a massive coincidence for us to find intelligent life that exists at the same time as us. It is more likely to be bacteria or microbes.

"It is unlikely that 'we' will exist for a further 100,000 years," he said.

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