gravitational waves


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gravitational waves

(gravitational radiation) Extremely weak wavelike disturbances that were predicted by Einstein's general theory of relativity. They represent the radiation associated with the gravitational force, and are produced when massive bodies are accelerated or otherwise disturbed. They are ripples in the fabric of spacetime that travel at the speed of light, with a wide range of frequencies, and carry energy away from the source. They should affect all matter: gravitational waves hitting a suspended body, for example, should make it vibrate slightly. The interactions are very small, however.

No conclusive direct evidence of the existence of gravitational waves has been forthcoming from the various highly sensitive experiments designed to detect them. Laser interferometers could be sufficiently sensitive. They consist of two identical extremely long tubes, set at right angles and with mirrors at both ends. A laser beam is split and sent down the tubes. A relative change in the two lengths would indicate a passing gravitational wave, and would be seen in the interference patterns produced when the reflected beams are recombined.

Gravitational waves should be emitted during supernova explosions or energetic events in the cores of active galaxies. They should also be emitted by two massive stars in close orbit. Recent observations of the binary pulsar PSR 1913+16 show that its orbital period is decreasing by 76 ± 2 microseconds per year. The observed value corresponds almost exactly with the decrease predicted to result from the emission of gravitational waves (75 μs per year) and is at present the best indirect evidence for their existence.

A quantum of gravitational radiation is known as a graviton, analogous to a photon.

References in periodicals archive ?
mergers and how gravitational waves are possible during such events.
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The search for gravitational waves has been the centre of current research in Astronomy and Cosmology.
"The smoking gun will be seeing the same pattern of deviations in all of them." Taylor and colleagues at JPL and the California Institute of Technology in Pasadena have been studying the best way to use pulsars to detect signals from low-frequency gravitational waves. Pulsars are highly magnetized neutron stars, the rapidly rotating cores of stars left behind when a massive star explodes as a supernova.
For centuries, gravity had been very successfully modeled by Isaac Newton's laws of gravitational force, and Newton's theory doesn't allow for anything like gravitational waves. Then came Einstein, who claimed that no signals of any sort can go faster than the speed of light.
Professor Sheila Rowan and Professor James Hough put the PS25 wager on in 2004 that researchers at the Laser Interferometer Gravitational Wave Observatory (Ligo) would "detect gravitational waves by 2010".
"Like the day Galileo first turned his telescope to the night sky, the detection of gravitational waves opens a new window on the universe.
Almost 100 years ago, the famous scientist Albert Einstein predicted the existence of gravitational waves or ripples in the fabric of space-time in 1916.
Making the announcement at the National Press Club in Washington DC, laser physicist Prof David Reitze, from the University of Florida, said: "Ladies and gentlemen, we have detected gravitational waves. We did it."
Einstein, who envisioned the space-time as a single entity that provides the celestial objects with a fabric to stay on, extended his way of thinking to predict the creation of ripples, known as gravitational waves, in the event of these masses change their positions in a significant way.
Washington, Jumada I 2, 1437, Feb 11, 2016, SPA -- A scientific collaboration that began decades ago to detect gravitational waves - described as ripples in the fabric of space-time - has for the first time borne fruit, US researchers announced Thursday, dpa reported.
Washington, DC, United States -- US astronomers announced Monday they have captured the first images of gravitational waves, or ripples in space-time described as the "first tremors"" of the Big Bang in which the universe came into existence 14 billion years ago.