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LIGO: The Search for Gravitational Waves
June 2002
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The LIGO facility at Hanford.
Credit: Caltech/NSF
LIGO scientists make adjustments to a
mirror in the contaminant-free "clean
room."
Credit: Caltech/NSF
Inside the LIGO tunnel at Livingston.
Credit: Caltech/NSF |
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The National Science Foundation (NSF) provides funding
for large, multi-user facilities that provide researchers
and educators with access to the latest technological
tools and capabilities. NSF also supports far-reaching
areas of science and engineering that hold promise
for breakthroughs that will enhance the nation's future
in profound, and possibly unpredictable, ways. The
Laser Interferometer Gravitational-Wave Observatory
(LIGO) is an example of both.
LIGO goals
- Take risks. Investing in leading-edge research
and education is a future-oriented endeavor, which
involves taking risks. Increasingly, it requires
international collaborations and integrating knowledge
across traditional disciplinary boundaries. And,
as science achieves measurements once considered
nearly impossible, it requires technological innovations
that were barely conceived of even a few decades
ago.
- Study the universe. For many years, telescopes
that detect and measure electromagnetic waves,
including visible light, have been the primary
means for astronomers and physicists to study
the universe. NSF's investment has enabled scientists
to reach out with an entirely new means of exploration--detectors
of gravitational waves. The LIGO project is spearheading
the completely new field of gravitational-wave
astronomy.
- Measure faint signals. Gravitational waves,
or ripples in the fabric of space-time, are produced
by violent events throughout the universe. LIGO
is designed to detect and measure these faintest
of signals reaching Earth from space and, at the
same time, test fundamental predictions of physics.
Its instruments are sensitive enough to measure
displacements as small as one-thousandth of the
diameter of a proton.
- Observe directly. Though Albert Einstein
predicted the existence of gravitational waves
in 1918 in his general theory of relativity, they
have never been directly observed. LIGO is expected
to provide the first hard evidence. By measuring
the effects of those waves on LIGO instruments,
scientists hope to make new discoveries and enrich
our understanding ocosmic phenomena such as black
holes, supernovae and pulsars.
- Network internationally. Scientists from
around the world collaborated on LIGO's design
and scientific objectives and will participate
in analysis of LIGO data. LIGO is the first of
an international network of detectors that together
will extract the maximum amount of information
about the sources of gravitational waves. Running
LIGO "in coincidence" with other detectors is
essential for ensuring confidence that gravitational
waves have been detected and for determining the
location and nature of the source.
- Create spin-offs. In addition to its direct
objectives, LIGO is reaping far-reaching scientific,
technological and industrial benefits. A laser
developed for LIGO by Stanford University scientists,
for example, has many potential applications.
Other spin-offs are expected in areas such as
measurement science, seismic isolation, vacuum
technology, coatings and optics.
- Educate. Educational outreach ensures that
the new knowledge reaches teachers and students,
encouraging the next generation of scientists.
Opportunities are available for middle schools,
high schools, colleges and universities to: analyze
LIGO data, contributing to knowledge about phenomena
such as gravitational waves, seismic and atmospheric
disturbances, and weather; participate in software
development; and conduct hands-on research alongside
LIGO scientists.
Cost
LIGO is the largest single enterprise undertaken by
NSF, with capital investments of nearly $300 million
and operating costs of more than $20 million/year.
Status
The two LIGO facilities at Hanford, Wash., and Livingston,
La., have been constructed and commissioned. The three
interferometers--two at Hanford and one at Livingston--have
been operated successfully alone, in coincidence with
each other, and with interferometers in Germany and
Japan; also with an older "bar"-type detector in Louisiana.
The first two rounds of LIGO scientific observations
are scheduled for summer and fall 2002.
Players
The LIGO project is headed by a team from the California
Institute of Technology and the Massachusetts Institute
of Technology. The LIGO scientific collaboration consists
of more than 350 scientists from more than 30 institutions
worldwide.
For more information, see: http://www.ligo.caltech.edu/
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