The Search for Extraterrestrial Intelligence
SETI (Search for Extraterrestrial Intelligence) is a scientific
area whose goal is to detect intelligent life outside Earth. One
approach, known as radio SETI, uses radio telescopes to listen
for narrow-bandwidth radio signals from space.
Such signals are not
known to occur naturally, so a detection would provide evidence of
Radio telescope signals consist primarily of noise (from celestial
sources and the receiver's electronics) and man-made signals such as TV
stations, radar, and satellites. Modern radio SETI projects analyze the
More computing power enables searches to cover greater
frequency ranges with more sensitivity. Radio SETI, therefore, has an
insatiable appetite for computing power.
Previous radio SETI projects have used special-purpose supercomputers,
located at the telescope, to do the bulk of the data analysis.
David Gedye proposed doing radio SETI using a virtual supercomputer
composed of large numbers of Internet-connected computers, and he
organized the SETI@home project to explore this idea. SETI@home was
originally launched in May 1999.
Most of the SETI programs in existence today,
including those at UC Berkeley build large computers that analyze that
data from the telescope in real time.
None of these computers look very
deeply at the data for weak signals nor do they look for a large class
of signal types (which we'll discuss further on...) The reason for this
is because they are limited by the amount of computer power available
for data analysis.
To tease out the weakest signals, a great amount of
computer power is necessary. It would take a monstrous supercomputer to
get the job done. SETI programs could never afford to build or buy that
There is a trade-off that they can make. Rather than a
huge computer to do the job, they could use a smaller computer but just
take longer to do it. But then there would be lots of data piling up.
What if they used LOTS of small computers, all working simultaneously on
different parts of the analysis? Where can the SETI team possibly find
thousands of computers they'd need to analyze the data continuously
streaming from Arecibo?
The UC Berkeley SETI team has discovered
that there are already thousands of computers that might be available
for use. Most of these computers sit around most of the time with
toasters flying across their screens accomplishing absolutely nothing
and wasting electricity to boot.
This is where SETI@home (and you!) come
into the picture. The SETI@home project hopes to convince you to allow
us to borrow your computer when you aren't using it and to help us
"…search out new life and new civilizations." We'll do this with a
screen saver that can go get a chunk of data from us over the internet,
analyze that data, and then report the results back to us. When you need
your computer back, our screen saver instantly gets out of the way and
only continues it's analysis when you are finished with your work.
It's an interesting and difficult task. There's so
much data to analyze that it seems impossible! Fortunately, the data
analysis task can be easily broken up into little pieces that can all be
worked on separately and in parallel. None of the pieces depends on the
Also, there is only a finite amount of sky that can be
seen from Arecibo. In the next two years the entire sky as seen from the
telescope will be scanned three times. We feel that this will be enough
for this project. By the time we've looked at the sky three times,
there will be new telescopes, new experiments, and new approaches to
SETI. We hope that you will be able to participate in them too!