Space-time ripples, exploding stars, colliding black holes …. and the National Institute of Standards and Technology? NIST doesn’t exactly come to mind when thinking about cataclysmic events in the cosmos. But behind the scenes, NIST played an essential supporting role in the Nobel Prize-winning discovery of ripples in spacetime — gravitational waves — which scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced in 2015. NIST researchers helped calibrate the gravitational-wave detector system, ensuring that the LIGO team accurately measured the historic event.
Now, the NIST scientists have more than doubled the accuracy of those calibrations. When LIGO resumes observations in mid-December, the new calibrations will enable astronomers to more accurately pinpoint the origin and nature of future space-time disturbances.
Front side of the radiometer developed at NIST (left) and view inside the vacuum chamber (right). The radiometer helps calibrate the power of infrared lasers used at LIGO to ever so slightly nudge the detector’s mirrored test masses, simulating the passage of a gravitational wave.
Credit: NIST
The first ripple ever directly detected arrived at LIGO’s twin sites in Louisiana and Washington state on Sept. 14, 2015. Generated by the collision of two black holes, the wave had journeyed 1.3 billion light-years to reach Earth. The detection provided stunning confirmation of Albert Einstein’s century-old prediction that massive bodies undergoing acceleration not only distort but actually shake space-time.
The discovery was also a technological feat. Each LIGO observatory features two L-shaped, 4-kilometer-long arms that form an exquisitely sensitive interferometer, a device that uses light to measure distance. When a gravitational wave passes by, it alternately compresses one arm while stretching the other by an amount much less than ..
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