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  • Exactly 100 years ago, in 1916, Albert Einstein

  • predicted the existence of gravitational waves, ripples

  • in the fabric of spacetime that are produced

  • by cataclysmic astrophysical events,

  • such as the collision of two black holes.

  • As they travel across the universe,

  • gravitational waves stretch and squeeze space and time.

  • One and a half billion years ago, two black holes that

  • were 30 to 40 times the size of the sun collided and they bent

  • spacetime around themselves.

  • This created waves that propagated,

  • traveled through the universe at the speed of light.

  • And on September 14, 2015, they've reached Earth

  • and we were ready to catch them.

  • We were able to do so thanks to a facility

  • called LIGO, the Laser Interferometer

  • Gravitational-Wave Observatory.

  • In Louisiana and in Washington state

  • there are two almost identical L-shaped detectors

  • that use lasers to measure the change in distance

  • between mirrors that are two and a half miles apart.

  • We're talking about changes in distance that are one

  • and 10,000th the size of a proton because that's how small

  • the effects of gravitational wave is on Earth.

  • When gravitational waves hits LIGO

  • they stretched and squeezed its arms.

  • And by doing so, they conveyed the message of something that

  • happened 1.5 billion years ago.

  • Within three minutes, we were alerted of this signal

  • and it was perfect, just as theory predicted it would be.

  • Within fractions of a second, the frequency and the amplitude

  • of the vibration increased with the unmistakable chirp pattern

  • that is expected for colliding black holes.

  • This is a groundbreaking discovery

  • that will open a new field of gravitational wave astronomy

  • where gravitational waves will be a new probe to explore

  • the mysteries of the universe.



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