Albert Einstein theorized the presence of gravitational waves nearly 100 years ago, but even he thought they would be impossible to find. In February of 2016, all that changed.
In 1992, teams from CalTech and MIT designed LIGO, the Laser Interferometer Gravitational-Wave Observatory. The mission of LIGO was to detect tiny fluctuations in spacetime caused by massive objects in the universe colliding and exploding, sending ripples of gravity in their wake.
LIGO went online in 2002, but never detected anything. It was refurbished in 2010 to be 4 times more sensitive, and after 5 years of improvements, came back online in 2015. This time, they almost immediately picked up a signal.
Afte 5 months of sifting through the data to make sure it's correct, LIGO scientists announced their findings on February 11th, 2016.
This did far more than just confirm one of Einstein's theories, it also opens up a new window on the universe and was the first time anything has been detected using something other than light.
It is literally creating an entirely new field of astronomy.