Comet Supercomputer at SDSC Helps Confirm Gravitational Wave Discovery

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Comet, SDSC’s petascale supercomputer

Comet, SDSC’s petascale supercomputer

The NSF-funded Comet supercomputer at SDSC was one of several high-performance computers used by researchers to help confirm that the discovery of gravitational waves before a formal announcement was made.

On September 14, scientists detected gravitational waves by both of the NSF-funded Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, according to the agency’s February 11 announcement. The waves reached Earth from the southern hemisphere, passed through the Earth, and emerged at the Earth’s surface, first at the LIGO interferometer near Livingston, Louisiana, and then, seven milliseconds later and 1,890 miles away at the second LIGO interferometer, in Hanford, Washington.

Scientists soon realized they had the tell-tale “chirp” signature of two black holes merging. At the moment of the collision, about three times the mass of the sun was converted into gravitational waves with a peak power outlet of about 50 times that of the whole visible universe, according to the NSF/LIGO announcement.

The collision of the two black holes happened 1.3 billion years ago, generating waves that have been traveling through the universe ever since. The discovery, however, immediately rippled with full force throughout and beyond the astrophysics research community, confirming Einstein’s belief that gravitational waves existed. That belief was an outgrowth of his groundbreaking general theory of relativity, which depicted gravity as a distortion of space and time triggered by the presence of matter.

Until now, scientists had found only indirect evidence of their existence. Einstein correctly thought that by the time the gravitational waves reached us they would be much weaker, so weak no one would ever be able to measure them. That’s only because he likely could not have imagined today’s technology that enables LIGO’s two detectors to detect movements that are a tiny fraction of the width of an atomic nucleus.

A computer simulation shows the collision of two black holes, a tremendously powerful event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO.

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