If aliens exist we'll know in 20 years

Jul 22 2004. ALIEN life will be discovered within 20 years or not at all, according to scientists who are scanning the skies for signs of intelligent life. Experts in California said yesterday they would need another two decades to finish analysing radio signals from 100 billion stars in the Milky Way. Their efforts were applauded yesterday by Wales' foremost astronomer, Prof Chandra Wickramasinghe, of Cardiff University, who accused critics of being impatient for results.

The Search for Extraterrestrial Intelligence (Seti) has already spent four decades checking radio waves for patterns that would betray the influence of intelligence. But despite finding nothing, the group has not lost heart.

Seth Shostak, senior astronomer at the Seti Institute in Mountain View, California, said signs of intelligent life - if any existed - would be found within 20 years. His claim was based on accepted assumptions about the chances of alien civilisations existing and on projected increases in computing power on Earth. Mr Shostak also estimated the number of alien civilisations in the Milky Way that might be broadcasting radio signals.

He used a formula created in 1961 which includes factors such as the number of stars with planets, how many of those planets might be expected to have life, and the likelihood of life evolving to an advanced stage. He concluded that there should be between 10,000 and a million transmitting aliens in the galaxy, according to a report in New Scientist magazine. To find them will involve observing and inspecting radio emissions from most of the Milky Way's 100 billion stars. The time necessary for this task can be estimated from the capabilities of planned radio telescopes - such as Seti's one-hectare Allen Telescope Array - and expected increases in the power of microchips that sift through the radio signals from space.

Within a generation, radio emissions from enough stars will be observed and analysed to find the first alien civilisation, Mr Shostak estimates. But because they will probably be between 200 and 1,000 light years away, a radio message sent from Earth would take centuries to reach the intelligent beings who sent the incoming signal. Prof Wickramasinghe, who has given talks to Seti, applauded the scientists' efforts.

"The criticism of this group has been to say that we've looked for intelligence for close on half a century and nothing has turned up, therefore there has to be nothing. I think that's an extremely false position to take."

"Forty years is too short a time to expect anything. We would be greedy if we expect the first hellos to come in the next 10 years.

"Twenty years is a more reasonable time to took forward to."

Prof Wickramasinghe is well known in astronomy circles as the proponent of a theory that the most basic elements of life drift around the cosmos and should have evolved into living organisms on other planets besides Earth. He said Seti had the right approach to the search for extra-terrestrial intelligence, using spare resources rather than devoting big money to the project. But Paul Shuch, executive director of the Seti League, a separate organisation in New Jersey, was unconvinced by Mr Shostak's latest prediction.

"It is altogether reasonable to project the development of human technology, based upon past trends and planned investments," he said.

"But predicting the date, the decade, or even the century of contact, is another matter because the 'other end' of the communication link is completely out of our hands.

"It would be nice to think we know something about the existence, distribution, technology and motivation of our potential communications partners in space, but in fact we don't."


Rhodri Clark, The Western Mail


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