Software sifts through gravity’s mysteries
Physicists kick off Einstein @ Home campaign
By Alan Boyle
Science editor
Updated: 6:26 p.m. ET Feb. 19, 2005

WASHINGTON - Physicists on Saturday kicked off a campaign to enlist
Internet users to help solve one of the biggest unresolved questions
surrounding Albert Einstein's general theory of relativity: Do
gravitational waves really exist?

Eighty-nine years ago, Einstein predicted that such ripples in
space-time should be set off by dramatic cosmic events, such as black
hole collisions and stellar explosions. But to date, no one has ever
detected the waves. Two sprawling observatories have been set up in the
United States and Germany to look for them, but analyzing the data from
those efforts requires an enormous amount of computing power.

That's where Einstein @ Home enters the picture.

The screensaver-type program was released to the public on Saturday in
conjunction with the  American Physical Society's World Year of Physics
celebration, marking the centennial of Einstein's initial theories on
relativity and quantum physics.

Einstein @ Home uses the same basic platform as SETI @ Home, which
signed up more than 5 million computers to sift through radio telescope
data for signs of extraterrestrial intelligence. In this case, users
can search through data from the U.S. Laser Interferometry
Gravitational Wave Observatory, or LIGO, as well as the British-German
GEO-600 gravity-wave observatory. The program looks for the faint
signals coming from very dense, rapidly rotating compact quark stars
and neutron stars — prime candidates for the continuous emission of
gravity waves.

Both observatories have only recently undergone enough fine-tuning to
detect the signals, if they exist.

What waves could tell

Detecting the waves would allow for deeper testing of Einstein's
theories and open up an entirely new avenue for research into the
workings of our universe, LIGO director Barry Barish said.

"Does gravity really travel at the speed of light, or is it different
from electromagnetic waves?" he asked. "That could be checked, for
example, if we saw a signal from these gamma-ray bursts. If we see
light traveling a certain speed, you could ask, 'Does the gravitational
signal arrive at the same time, earlier, later?'"

In the longer term, gravity-wave study could provide a "completely
different way of looking at the universe," Barish said. Such research
could help unravel the mysteries of dark matter and dark energy —
features that dominate our cosmos but are not yet adequately explained
by Einstein's theories.

"The most romantic goal is to be to able to see signals from the early
universe with gravitational waves," Barish said. "They would be the
most valuable of all, because they're not absorbed like photons or
electromagnetic waves are. It allows you to probe back to the very
first instants after the Big Bang."

On the other hand, if LIGO and GEO-600 do not detect gravitational
waves, that would cast a cloud of uncertainty over general relativity
and our understanding of gravity itself.

Einstein @ Home's public unveiling came during the American Association
for the Advancement of Science's annual meeting in Washington.

The software has been in beta testing for months, with 10,000 users
signed up in advance of Saturday's public release, said the project's
principal investigator, Bruce Allen of the University of Wisconsin at
Milwaukee. Allen hopes hundreds of thousands of users will join the

Versions are available for Windows, Linux and Mac operating systems.
Once the program is installed — a process that should take no more than
a couple of minutes — it downloads data in the background automatically
from a central computer, analyzes the data while a user's computer is
idle, then uploads the results back to the server.

Each 12-megabyte chunk of data will be analyzed three times, and the
most intriguing signals will be flagged for the project scientists.

"Anything that survives the initial screening ... we can follow up on
ourselves," Allen told

Visit the Einstein @ Home Web site for more information and downloads.
© 2005 MSNBC Interactive