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If intelligent life exists elsewhere in our galaxy, advances in
computer processing power and radio telescope technology will ensure we
detect their transmissions within two decades. That is the bold prediction
from a leading light at the Search for Extraterrestrial Intelligence
Institute in Mountain View, California.
Seth Shostak, the SETI Institute's senior astronomer, based his
prediction on accepted assumptions about the likelihood of alien
civilisations existing, combined with projected increases in computing
power.
Shostak, whose calculations will be published in a forthcoming edition
of the space science journal Acta Astronautica, first estimated the
number of alien civilisations in our galaxy that might currently be
broadcasting radio signals.
For this he used a formula created in 1961 by astronomer Frank Drake
which factors in aspects such the number of stars with planets, how many
of those planets might be expected to have life, and so on. Shostak came
up with an estimate of between 10,000 and one million radio transmitters
in the galaxy.
To find them will involve observing and inspecting radio emissions from
most of the galaxy's 100 billion stars. The time necessary for this
formidable task can be estimated from the capabilities of planned radio
telescopes such as SETI's 1-hectare Allen Telescope Array and the
internationally run Square Kilometre Array and expected increases in the
power of the microchips that sift through radio signals from space.
Alien civilisation
Shostak assumed that computer processing power will continue to double
every 18 months until 2015 � as it has done for the past 40 years. From
then on, he assumes a more conservative doubling time of 36 months as
transistors get too small to scale down as easily as they have till
now.
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Within a generation, radio emissions from enough stars will be
observed and analysed to find the first alien civilisation, Shostak
estimates. But because they will probably be between 200 and 1000
light years away, sending a radio message back will take
centuries.
Paul Shuch, executive director of the SETI League, a separate
organisation in New Jersey, says Shostak's prediction ignores one
important factor. "It is altogether reasonable to project the
development of human technology, based upon past trends and planned
investments," he says.
"But predicting the date, the decade or even the century of
contact is another matter because the 'other end' of the
communications 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."
Shostak admits that there are myriad uncertainties surrounding
his prediction, but he defends the basis on which he made it. "I
have made this prediction using the assumptions adopted by the SETI
research community itself." |
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Marcus Chown
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