Gravitational Waves: Ripples in Spacetime

Gravitational waves are ripples in the fabric of spacetime, predicted by Albert Einstein's general theory of relativity over a century ago. They are produced by some of the most violent events in the universe, like the collision of black holes and neutron stars, and travel at the speed of light. First directly detected in 2015, they have opened a new window on the universe, allowing us to observe cosmic events that are invisible to traditional telescopes.