Theory of Relativity in Space: Latest science, tests and images

For some skywatchers, the upcoming total solar eclipse is an opportunity to duplicate one of the most famous experiments of the 20th century.

In the season finale of "Genius," Albert Einstein lives out his twilight years as an American citizen.

In Chapter 7 of Nat Geo's "Genius," the pressure is on as Einstein races to prove his theory of relativity amid an uproar of criticism from the scientific community.

It's not a fluke: For the third time, the LIGO gravitational wave observatory has detected ripples in space-time caused when two black holes circle each other at mind-bending speeds and collide.

The vacuum of empty space may be roiling with energy that drives the expansion of space itself, a new hypothesis proposes.

A massive cosmic object can act like a lens, magnifying and warping the images of background bodies. Learn all about this "gravitational lensing" phenomenon in the third episode of "We Don't Planet."