Learn about gravitational waves and how they can be detected, in this video from NOVA: Black Hole Apocalypse. According to Einstein's general theory of relativity, massive accelerating objects create ripples in spacetime. In the 1970s, Rainer "Rai" Weiss developed the idea to build a laser interferometer to detect this stretching and squeezing of spacetime—gravitational waves. Animations illustrate the basic principle behind the device: a beam of light travels through a splitter, toward two different mirrors, and then the reflected beams of light rejoin. If the distance the light travels along each arm is the same, the beams cancel each other out; however, if a gravitational wave changes the distances, the beams no longer cancel out and a photodetector senses light. This resource is part of the NOVA: Black Hole Apocalypse Collection.
Visit the program page.