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  Scientists have for the first time observed ripples in the fabricof spacetime called gravitational waves, arriving at the earth froma cataclysmic event in the distant universe. It confirms a majorprediction of Albert Einstein’s 1915 general theory of relativityand opens an unprecedented new window to the cosmos, according to agroup of scientists at a press conference in Washington onThursday.
  “This is truly scientific moonshot. We did it. We landed on themoon,” exclaimed David Reitz, executive director of the LIGOLaboratory at Caltech, at the conference in the National PressClub.
  According to the National Science Foundation (NSF) experts,gravitational waves carry information about their dramatic originsand about the nature of gravity that cannot be obtained fromelsewhere. Physicists have concluded that the detectedgravitational waves were produced during the final fraction of asecond of the merger of two black holes to produce a single, moremassive spinning black hole. This collision of two black holes hadbeen predicted but never observed.
  The gravitational waves were detected on Sept 14, 2015 at 5:51 amEDT by both of the twin Laser Interferometer Gravitational-waveObservatory (LIGO) detectors, located in Livingston, Louisiana, andHanford, Washington.
  Based on the observed signals, LIGO scientists estimate that theblack holes for this event were about 29 and 36 times the mass ofthe sun, and the event took place 1.3 billion years ago. Aboutthree times the mass of the sun was converted into gravitationalwaves in a fraction of a second -- with a peak power output about50 times that of the whole visible universe. By looking at the timeof arrival of the signals -- the detector in Livingston recordedthe event 7 milliseconds before the detector in Hanford --scientists can say that the source was located in the SouthernHemisphere, according to a press release from NSF, which funded theresearch.
  According to general relativity, a pair of black holes orbitingaround each other lose energy through the emission of gravitationalwaves, causing them to gradually approach each other over billionsof years, and then much more quickly in the final minutes. Duringthe final fraction of a second, the two black holes collide atnearly half the speed of light and form a single more massive blackhole, converting a portion of the combined black holes’ mass toenergy, according to Einstein’s formula E=mc2. This energy isemitted as a final strong burst of gravitational waves. These arethe gravitational waves that LIGO observed.
  The existence of gravitational waves was first demonstrated inthe 1970s and 1980s by Joseph Taylor, Jr., and colleagues. In 1974,Taylor and Russell Hulse discovered a binary system composed of apulsar in orbit around a neutron star. Taylor and Joel M. Weisbergin 1982 found that the orbit of the pulsar was slowly shrinkingover time because of the release of energy in the form ofgravitational waves. For discovering the pulsar and showing that itwould make possible this particular gravitational wave measurement,Hulse and Taylor were awarded the 1993 Nobel Prize inPhysics.
  The new LIGO discovery is the first observation of gravitationalwaves themselves, made by measuring the tiny disturbances the wavesmake to space and time as they pass through the earth.
  “Our observation of gravitational waves accomplishes an ambitiousgoal set out over five decades ago to directly detect this elusivephenomenon and better understand the universe, and, fittingly,fulfills Einstein’s legacy on the 100th anniversary of his generaltheory of relativity,” Reitze said.
  LIGO research is carried out by the LIGO Scientific Collaboration(LSC), a group of more than 1,000 scientists from universitiesaround the United States and in 14 other countries. More than 90universities and research institutes in the LSC develop detectortechnology and analyze data; approximately 250 students are strongcontributing members of the collaboration.
  “This detection is the beginning of a new era: The field ofgravitational wave astronomy is now a reality,” says GabrielaGonzalez, LSC spokesperson and professor of physics and astronomyat Louisiana State University.
  LIGO was originally proposed as a means of detectinggravitational waves in the 1980s by Rainer Weiss from MIT; KipThorne and Ronald Drever, both from Caltech.
  “The deion of this observation is beautifully described in theEinstein theory of general relativity formulated 100 years ago andcomprises the first test of the theory in strong gravitation. Itwould have been wonderful to watch Einstein’s face had we been ableto tell him,” Weiss said.
  “With this discovery, we humans are embarking on a marvelous newquest: the quest to explore the warped side of the universe --objects and phenomena that are made from warped spacetime.Colliding black holes and gravitational waves are our firstbeautiful examples,” said Thorne.
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