8. Gravitational waves

In 1916, Einstein published his theory of general relativity, which incorporated fundamentally new ideas about the nature of gravity, including that gravitational effects take time to travel. He also showed that under some circumstances, objects lose energy by emitting ‘ripples’ in time and space: gravitational waves. ‘Gravitational waves’ explains how these waves are very weak and only the most powerful events in the Universe generate strong enough versions to be detected. Gravitational waves differ from other kinds of waves as their only effect is to cause objects to move together and then apart again. They provide a unique new window on the Universe, allowing us to look deeper and further than ever before.