The Einstein@home screensaver will scan the sky for bell-like vibrations in space-time.
© B. Allen, Einstein@home
Physicists hope to exploit the downtime of a million machines.
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The Einstein@home screensaver will scan the sky for bell-like vibrations in space-time. © B. Allen, Einstein@home |
Scientists
searching for waves
of gravitational energy that stretch space and time will soon be
seeking the public's help in analysing their data.
Researchers
at the Laser Interferometer Gravitational Wave Observatory (LIGO)
hope to enlist up to a million personal computers in their search for
sources of the waves, which have long been predicted but never seen.
Their distributed-computing scheme, set to launch this month,
aims to be one of the largest projects of its kind ever created. The
software is already in beta testing.
Albert Einstein's general
theory of relativity lays out the idea that gravity distorts space
and time. As a test of his theory, Einstein predicted that waves of
gravity would ripple through the cosmos. Some claim such waves have
been spotted indirectly, from observations of how paired stars
influence each other's orbits, but nobody has seen them
firsthand.
Since 2000, researchers at LIGO have scanned the
sky for tiny shifts of space that would prove Einstein's theory. The
project is being built by the California Institute of Technology and
the Massachusetts Institute of Technology on two sites, one in
Livingston, Louisiana and the other in Hanford, Washington. It uses a
system of lasers and mirrors that can detect a shift in space as
small as the width of an atom.
Bell ringers
LIGO's
best hope for detecting gravity waves is to spot a cosmic source that
sends out regular ripples of gravitational energy. A source such as a
spinning star made of neutrons would set the detectors ringing like a
bell.
The problem is that the detectors pick up an enormous
number of unwanted vibrations. "It's a needle in a haystack
problem: 99.99% of the data is noise," says Bruce Allen, a
physicist at the University of Wisconsin at Milwaukee.
"This
kind of search is not anywhere near possible with our LIGO computing
facilities," adds Barry Barrish, head of the collaboration and a
physicist at the California Institute of Technology, Pasadena. The
data must be analysed at many frequencies, increasing the computer
power needed.
So the group is enlisting the public's help.
Starting in February, anyone can download a
program
that will
automatically analyse a small chunk of the group's data on his or her
personal computer.
The project, known as Einstein@home, will
use the computer's idle time to search particular frequencies for a
'ringing' gravity wave source. While it's at work, the programme also
displays a screensaver charting the location of the search in the
night sky. "It's really a cool kind of project," Allen
says.
Einstein@home joins a growing number of
distributed-computing projects. The original, SETI@home, launched in
1999 to search for signals from extraterrestrials, has attracted more
than 5 million users. More recent attempts to model everything from
climate change to protein folding have enlisted hundreds of thousands
of home computers.
Einstein@home will be among the most
ambitious of such projects, Allen says. LIGO is generating data sets
so large, and looking for a signal so small, that it will take around
a million active users to make a dent. But, he adds, the more the
merrier: the data set is so massive that "even all the computers
on the planet wouldn't be enough".
Published online: 1 February 2005; | doi:10.1038/news050131-7