Short answers, pulled from the story.
Oliver Heaviside proposed the existence of gravitational waves in 1893. He used an analogy between the inverse-square law of gravitation and electrostatic force to suggest that gravity might behave like light.
The LIGO observatory detected its first signal on the 14th of September 2015 at 09:50:45 GMT. Two black holes with masses of 29 and 36 solar masses merged about 1.3 billion light-years away to create this event.
Russell Alan Hulse discovered a binary pulsar system named PSR B1913+16 in 1974. Observations over the next decade showed the orbital period decreased gradually, matching predictions from general relativity for energy lost to gravitational radiation.
LIGO has arms four kilometers long running through vacuum tubes one meter wide. Passing waves stretch one arm while shortening the other by roughly 10^-18 meters.
BICEP2 announced detection on the 17th of March 2014 but withdrew it the 30th of January 2015 due to dust interference. Planck experiment results confirmed limits matching Lambda-CDM models instead.