Einstein would be happy: Researchers at LIGO announced the detection of gravitational waves. Simulations indicate that the signal is originated by the merging of two black holes which collided 1.3 billion light-years away. The LIGO experiment is made of two facilities separated 3002 km. Each site has two L-shaped ultra-high-vacuum arms, 4 km long on each side, containing several interferometers. Distortions in the space-time caused by a gravitational wave produce an astonishing small -yet detectable- signal equivalent to 1 part in 10²¹. Watch the videos from ligo.org or download a ring tone for your cell phone! This does not happen everyday.