LIGO, that famous L-shaped laboratory near Hanford that confirmed the existence of gravitational waves, proving one of Einstein's theories, has discovered a THIRD black hole event (a third gravitational wave event).

If you're not familiar with the back story, the simple explanation is that Einstein believed the universe had some characteristics similar to a stretched blanket. And if there was a major event, like black holes swallowing each other, or a huge sun, that should create ripples across the blanket -- gravitational waves.

LIGO, along with a sister facility in Louisiana, detected such a gravitational wave. There needs to be two labs to make sure something else doesn't cause the vibrations. When they both read the same vibrations at the same time and they're the same shape, the scientists know it's legitimate.

Now LIGO has seen THREE such events. Why is three a big deal? Because three confirms there was no coincidence, no fluke.

Also because three confirms the existence of black holes -- the only things large and powerful enough to CREATE these gravitational waves that can be detected millions of light years away.

Prior to this, they were still technically theoretical. Scientists could point at where they THINK black holes exist, but couldn't prove they were there. Now Albert Einstein is validated, including his theory about black holes (and all the theoretical physicists since then).

Getty Images, NASA