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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