The LIGO (Laser Interferometer Gravitational Wave Observatory) experiment has a strong signal for gravitational waves emitted from a binary black hole system that had two black holes actually merge together to form a single, larger black hole. The signal, observed by both LIGO facilities in Louisiana and Washington in September, 2015, matches the predicted signal from Einstein's general theory of relativity.
This is a big day for astronomers and astrophysicists who have pondered the existence of these waves, predicted by Einstein in 1916, for almost exactly one century. This is a technical marvel of an experiment to detect incredibly weak vibrations caused when a gravitational wave passes through objects and very slightly distorts their dimensions in various ways due to the stretching in space-time. A shout-out to my friend Vicky Kalogera at Northwestern, who is a member of the collaboration.
See a New York Times article here, and read the actual Physical Review Letters paper here!