Picture of Martyn Overy
Searching for Extraterrestrial Intelligence
by Martyn Overy - Saturday, 5 July 2003, 12:17 PM

SETI@home has used the power of millions of computers around the world, and has analysed over 5 million signals from space. 

At the University of California at Berkeley, Dan Werthimer, David Anderson, and Eric Korpela have reduced the enormous number of signals to about 200. These will now form the basis of an extended analysis.

So how did they narrow down all the signals to just 200? Certain criteria are required, to increase the likelihood of the transmissions being 'real' :

1. Signals observed in the same location in the sky on two or more telescope passes.

2. Signals observed on similar frequencies during different passes. This allows for any Doppler shifts.

3. Strong signals that provided a power-versus-time curve known as a Gaussian curve.

4. Signals that were not linked with any known sources of Earth borne interference or local or distant satellite signals.

5. Sources originating near a known star or galaxy.

6. Sources adjacent to a main sequence star similar to our sun. These are more likely to provide planets with similar conditions as Earth

What is the probability of detecting a signal from an extraterrestrial intelligent source. The odds are in the region of 1 in 10,000 according to project leader. Most of the signals are expected to be the result of man-made interference.

SETI has only been looking for extraterrestrial life, by searching for 'signals for a very short time in the age of our universe. This is a very small 'blip' on a time scale that is so enormous that the human mind can hardly appreciate the vast space that exists between us and the likely candidates for intelligent life. Even if we do eventually receive a 'message' , we will be receiving one which probably had its origin millions of years ago, such is the time it take light to travel across these vast distances. How on earth do we communicate with such a distant source, even if it still exists?

Need to find out more? Visit the SETI website:

SETI Website