Einstein@Home: Astrophysics for the Masses
James Riordon, American Physical Society
One of the great challenges the physics community and scientists in general face is
informing the general public about the importance of scientific research, both for our
future and in our everyday lives. Formal classroom education and informal educational
efforts are among the time tested ways to address the challenge. In recent years, however,
new ideas have been developed that go beyond simply educating the public. Distributed
computing projects allow anyone who owns a personal computer to make a real and vital
contribution to scientific research. Such projects often include informal science
education components. Perhaps more importantly, people who join the computing efforts are
participating in real scientific research and developing increased appreciation for the
benefits that science offers.
It is with
these things in mind that the American Physical Society spearheaded the launch of the
world's first physics research-based distributed computing project, Einstein@Home, as
one of the cornerstone projects for the World Year of Physics 2005. Einstein@Home relies
on donated computational power from private PCs to analyze gravitational wave data for
signals emanating from extremely dense, rapidly rotating neutron and quark stars.
General Theory of Relativity predicts that accelerating massive objects should radiate
gravitational waves. New detectors in the US and Europe have now been built to detect
those waves. Supernova stars, colliding black holes, and other violent events likely
produce the largest gravitational bursts and are good candidates for detectable signals.
quark stars and neutron stars should also emit gravitational waves, if they are not
perfectly spherical. Unlike the sudden bursts of violent events, rotating aspherical
objects would create continuous gravitational waves, at twice the objects' rotational
frequencies. The signal frequencies would gradually decrease as gravitational radiation
saps the rotational energy. This phenomenon has already been confirmed circumstantially
through the observation of the spin down of binary star pairs. Detecting continuous waves
with gravitational observatories, however, presents extraordinary computational
pulsars may emit gravitational signals, but it is likely that most strong sources of
continuous gravitational waves are not detectable via conventional astrophysical
observation techniques, such as visible, x-ray, or radio astronomy. Ideally, researchers
would like to perform whole sky, point-by-point searches for continuous wave sources. The
computational demands of this kind of search would be daunting even for the most powerful
supercomputers currently in existence.
computing projects have recently been developed to address certain types of
computationally intensive problems by tapping into the excess computational power of
privately owned PCs. SETI@Home is one of the first and most popular distributed computing
efforts. Participants install a screensaver-based program that downloads and analyzes
small portions of data collected from the Arecibo radio antenna in Puerto Rico to
search for signals indicative of intelligent activity in space. Other distributed
computing projects are currently underway to model protein folding (Folding @Home), search
for prime numbers (the Great Internet Mersenne
Prime Search), and model the Earth's climate (ClimatePrediction.net). The computational
capacities of SETI@Home and several other projects currently exceed the power of the world's
fastest supercomputer, IBM's BlueGene/L, sometimes by factors of two or three. Typical
distributed computing projects achieve their capacities by involving tens to hundreds of
thousands of PC owners. Clearly, the potential for large computational capacity and
extensive public participation makes distributed computing an ideal tool for scientific
research, public outreach, and informal education.
2004, the APS World Year of Physics team approached LIGO spokesperson Peter Saulson with a
proposal to promote a distributed computing effort for gravitational data analysis as a
flagship project in the World Year of Physics 2005 celebration. By mid 2004, Bruce Allen
of the University of Wisconsin-Milwaukee was leading an international team of scientists
and engineers in writing code and assembling hardware for the project. Primary
institutions contributing to the project include the LIGO Scientific Collaboration (LSC),
the Albert Einstein Institute in Berlin, the University of Glasgow, the Massachusetts
Institute of Technology, and the University of Pennsylvania. Allen and LSC director Barry
Barish officially announced the launch of Einstein@Home on February 19, 2005.
like SETI@Home, is a screensaver-based program. Participants obtain software from the
Einstein@Home web page. After they install it, the program downloads several megabytes of
gravitational wave data. When a personal computer is idle for a period of time specified
by the computer user, the Einstein@Home screensaver is activated and the data analysis
algorithm runs. The program automatically uploads the analysis results to one of the
Einstein@Home servers and requests more data.
Top Left: LIGO, Hanford, WA
Top Right: LIGO, Livingstone, LA
Left: GEO600, Hannover, Germany
Einstein@Home screensaver displays a rotating image of the celestial sphere with the major
constellations outlined. Red points on the sphere indicate locations of supernova
remnants, and purple points indicate known pulsars. Three L-shaped markers represent the
directions that the gravitational wave observatories that contribute data to Einstein@Home
are pointing: a small red marker represents the 600 meter GEO600 interferometer
observatory in Hanover Germany; a green marker represents the 4 km interferometer in
Livingston Louisiana; and a blue marker represents the 2 km and 4 km interferometers in
Hanford, Washington. A moving, gun sight marker indicates the locations in the sky where
the computer is actively searching for gravitational wave signals.
was built on the Berkeley Open Interface for Network Computing (BOINC), a distributed
computing framework developed by SETI@Home pioneer David Anderson. The BOINC-based system
allows users to contribute to multiple distributed computing projects, in proportions that
the user selects. This allows people who currently subscribe to SETI@Home and other
projects to dedicate a portion of their computer's time to Einstein@Home as well.
In a matter
of four months Einstein@Home has become one of the largest and fastest growing distributed
computing projects in the world. As of June 1, 2005, over 80,000 people had signed up to
participate in Einstein@Home, and nearly 45,000 participants, representing approximately
140 countries, have completed at least some data analysis. The project typically analyses
data at a rate of about 80 teraFlops (80 trillion floating point operations per second) or
more, significantly outpacing IBM's record-setting BlueGene/L (70 teraFlops).
survey indicates that most of the Einstein@Home participants are male scientists and
engineers. The APS is currently working to diversify the user base through paid
advertising, direct mailing, and media promotion. Articles featuring Einstein@Home have
appeared in major newspapers and magazines around the world, and the project has been the
subject of numerous radio and television broadcasts.
presents an ideal opportunity for formal and informal education. Message boards on the
Einstein@Home web page host lively discussions of physics at levels ranging from
elementary introductions to graduate student subjects. Instructors at the Southern
University of Baton Rouge reported at the 2005 APS annual meeting in Tampa, Florida that
Einstein@Home has helped increase student interest and enrollment in physics classes
addressing gravitation and related topics. In Israel, Zvi Paltiel of the Weizmann
Institute of Science has organized explanatory material in Hebrew and arranged lectures
and workshops encouraging high school students to join Einstein@Home.
particularly appropriate, as we celebrate the centennial of Albert Einstein's annus
mirabilis, that Einstein@Home is helping to search for signs of gravitational waves
predicted by Einstein's Theory of General Relativity. Although Einstein did not complete
it until 1916, the path to General Relativity began with his work on Special Relativity in
miraculous year serves as the inspiration for the World Year of Physics 2005 celebrations,
but Einstein@Home will live on after the celebrations conclude. With a little luck, the
program will begin to find gravitational sources in coming years. Regardless of the
ultimate outcome, the project will continue to grow as a vital scientific, educational,
and outreach effort.
more about Einstein@Home and join the project, visit the World Year of Physics 2005 home
page at www.physics2005.org.
James Riordon is the head of media relations for the American
Physical Society. He was responsible for the initial conception of Einstein@Home as a
World Year of Physics 2005 project. He worked as a freelance science writer for seven
years prior to his position at the APS, and began his career as an applications physicist
with the short-lived Superconducting Super Collider in Waxahachie, Texas.