100 years after Albert Einstein predicted the existence of gravitational waves through his theory of general relativity, a team of astrophysicists has announced the detection of these distortions made in the fabric of space. "With this new discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the Universe—objects and phenomena that are made from warped spacetime," remarks gravitational physicist Kip Thorne.
Using the recently-upgraded Laser Interferometer Gravitational-Wave Observatory [LIGO], a signal was recorded on September 14, 2015, four days before the observatory was to officially begin observations. The source was tracked back to a pair of merging black holes, one 36 times the mass of the Sun, and the other 29 masses, 1.3 billion light years away. In the fraction of a second when the two masses merged, 4.6 percent of their mass — about the mass of three suns — was converted directly into energy, briefly outshining the energy released from all of the stars and galaxies of the observable universe by ten times. This energy release created distortions in spacetime, generating gravitational waves that spread outward into the universe.
These waves, however, are extremely weak: the LIGO detector was designed to be sensitive enough to detect vibrations smaller than 1/1,000th of a proton. The observatory currently consists of two L-shaped detectors, one in Washington State, the other in Louisiana, each with 4 km (2.5 mile) long arms that house two laser beams. Under normal, calm circumstances, the wavelengths of the two beams in each facility cancel each other out, resulting in no light being detected from the lasers by the observatory. But when a gravitational wave perturbs the array, the two wavelengths fall out of sync, and the observatory records the resulting light.
"This detection is the beginning of a new era: the field of gravitational wave astronomy is now a reality," explains Gabriela González of Louisiana State University. With more LIGO-style facilities under construction, the ability to detect gravity waves could open up the study of astronomical events that would otherwise have remained invisible.
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