In a validation of Albert Einstein's genius, the power of new technology, and the relevance of the scientific method (even if it takes a century), scientists working on a project called LIGO have witnessed ripples in the fabric of spacetime caused by gravitational waves. First predicted by Einstein in 1916 on the basis of general relativity, gravitational waves are cosmic shock waves that can result from the interactions of massive objects like black holes and neutron stars. Unlike electromagnetic waves, which pass through space, gravitational waves change the shape of space itself. Extremely perceptive observers would find themselves in a funhouse as gravitational waves passed through, watching objects and distances get bigger and smaller without actually moving a micron: seeing solid matter jiggle like jello.
LIGO's results are the most sensational in physics since the observation of the Higgs boson in 2013. Ethan Siegel puts the discovery into perspective on Forbes, writing "we’ve just detected two merging black holes for the first time, tested their physics, found a tremendous agreement with Einstein, and seen evidence that this happens over a billion light years away across the Universe." Meanwhile Greg Laden says "the gravity of this situation" deserves a newton of skepticism until scientists can repeat their result. And on Dynamics of Cats, Steinn Sigurðsson shares videos from the LIGO team to help everyone understand the project.