Gravity (from Latin gravitas 'weight'), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are attracted to (or gravitate toward) one another.
The veteran gravitational wave hunter from Glasgow University has come to the National Press Club in Washington DC to witness the announcement of the first direct detection of ripples in the fabric of space-time caused by the merger of two "intermediate-sized" black holes.
Imagine the energy of eight Suns released in an instant. This is the gravitational "shockwave" that spread out from the biggest merger yet observed between two black holes.
The idea rests on probing any minuscule variations in gravity as it acts on slow-moving neutrons in a tiny cavity. These quantum jumps can test Newton's theory of gravity - and any variations from it - with unprecedented precision.