Detecting the Undetectable: In Search of the Elusive Gravity Waves

By Mr Ghaz, June 19, 2010

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Detecting the Undetectable: In Search of the Elusive Gravity Waves

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In 1687 The English physicist Isaac Newton published his formulating the laws of gravity. He described it as a universal force that all objects on others by reason of their mass. Gravity made the apple fall on Newton’s head, and it kept the planets in their orbits around the sun.

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Newton’s laws became the cornerstone way scientists perceived the universe for more than two centuries. For Albert Einstein, however they were not sufficient. Newton’s theory explained how the force of gravity affected objects, but it did not explain what gravity was.

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According to the complex mathematical logic of Einstein’s general theory of relatively, gravity is a form of radiation emitted by accelerating bodies. Therefore it should be detectable waves moving through space at the speed of light, creating minute, fleeting deformations in a solid or liquid object as they pass.

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However, despite the theoretical existence of such waves, none had ever been detected. In practice, only waves generated by massive bodies under extreme acceleration – such as double stars collapsing into each other, or matter rushing into a black hole – were thought to be strong enough to be observed. Gravity waves emitted during less violent circumstances were thought to be so weak that they were virtually nonexistent.

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Detecting the Undetectable

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The search for gravity waves began in earnest in the early 1960’s. American scientist Joseph Weber built two gravity waves antennas consisting of large cylinders of pure aluminum. To these he attached highly sensitive vibration detectors; he hoped they would register any gravity waves passing through the antennas. In 1969 Weber announced that he was recording one gravity wave daily. But other researchers were unable to confirm or duplicate his results. Nevertheless, the Weber method is still applied in the search for gravity waves today.

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Modern gravity wave antennas are rods made either of aluminum or of the metal niobium. The rods are isolated from the slightest external shock and cooled to – 460°F. At that temperature the aluminum atoms almost cease to vibrate. Within the cylinders, vibrations of less than the diameter of the nucleus of an atom can be registered.

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In May 1986, results were compared from three gravity detectors – two in the United States and one in Europe. Although each recorded 60 to 70 disturbances, a day, none of the observations coincided exactly. The researcher’s conclusion: no gravity waves had been detected after all.

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Measuring the Universe

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However, scientists remain convinced that the search for gravity waves is not a wild goose chase. Today, the equipment has been upgraded with some advanced laser technologies to achieve levels of accuracy many times greater than that of current equipment.

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Plans exist to build two of the new instruments in the United States and one each in Germany and in Scotland. The designers predict that not only will the equipment record gravity waves for the first time but that it will continue to do so, on a regular basis. Working in unison, the detectors will, in addition, act as a kind of gravity telescope, able to pinpoint black holes, neutron stars, binary star system, and other sources of gravity waves.

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One result of these observations will be that astronomers can calculate, to an accuracy of about 3 percent, the distance that waves have traveled from their source. Armed with this information, scientists will have a far more accurate idea of the true scale of the universe.

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If everything goes as planned, gravity waves, may at least cease to be objects of purely theoretical interest and prove to have practical application. But first, they must be found.

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