LIGO detects third gravitational wave event from ancient black hole collision

Brittany A. Roston - Jun 1, 2017, 4:43 pm CDT
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LIGO detects third gravitational wave event from ancient black hole collision

The LIGO Scientific Collaboration has made another monumental announcement related to LIGO, the Laser Interferometer Gravitational-Wave Observatory — it has detected a gravitational wave event for the third time, a process that has been billions of years in the making. Before this detection is the story of two massive black holes that collided about three billion years ago, leaving behind one giant black hole approximately 49 times heavier than our Sun…and energy that would, over the past 18 months, wash over our planet three times.

When separated, these two black holes had masses estimated at about 32 times and 19 times that of our Sun. When merged, the pair produced what Caltech describes as ‘pure gravitational wave energy’ converted from two solar-masses’ worth of the black-hole mass. It only took about 0.12-seconds for all of that gravitational wave energy to be released, and the resulting waves have been traversing the universe for the last three billion or so years since.

To help put that in perspective (if such a thing is even possible), three billion light-years is equal to about 1/5th the distance to what researchers refer to as the edge of the visible universe. It is, in the truest sense of the word, astronomical.

Despite the huge amounts of energy and time involved in this event, however, the gravitational waves remain hard to detect on Earth — researchers describe their effects on LIGO’s arms as a ‘shudder,’ though they’re much smaller than that. The observatory’s arms stretched and shrunk in response to the passing gravitational wave by 1×10-18 meters — that is, by 0.000,000,000,000,000,001 meters, or by an amount that is 1,000 times smaller than the size of a single proton, according to Caltech.

Per the LIGO Scientific Collaboration, this third gravitational wave event was detected on January 4, 2017 a bit after 5AM EST. The waves were detected first in Hanford, Washington, where LIGO’s interferometer reacted, and yet again in Virginia, where another interferometer noted the energy a mere 3ms later. In the analysis following the detection event, researchers concluded that the data was in agreement with Albert Einstein’s predictions of general relativity, something made more than 100 years ago.


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