Gravitational waves have not been directly detected by laboratory instruments here on Earth. The LIGO and VIRGO collaborations are looking for gravitational wa

Gravitational waves have not been directly detected by laboratory instruments here on Earth. The LIGO and VIRGO collaborations are looking for gravitational waves by using large laser interferometers, but haven't detected any yet. The article is referring to the first indirect detection of gravitational waves. Binary stars emit gravitational waves which carry energy away from the system. The loss of energy causes the two stars to spiral into a closer orbit until eventually they merge. Using general relativity, you can predict how the semi-major axis will change as a function of time [1]. Hulse & Taylor measured the change in semi-major axis in a binary pulsar and found that it matched the predictions of general relativity. [1] http://adsabs.harvard.edu/abs/1964PhRv..136.1224P http://adsabs.harvard.edu/abs/1964PhRv..136.1224P