Gravity’s Century: From Einstein’s Eclipse to Images of Black Holes

This gracefully written history of 20th-century gravity research from science writer Cowen shines a light on a key aspect of modern physics. As he explains, the current view of gravity began with a young Albert Einstein’s curiosity about what a beam of light might look like. Cowen describes how Einstein eventually published the theory of general relativity in 1916, predicting how gravity would bend light. Proving this required photographing a solar eclipse in 1919 and seeing whether, as the theory predicted, the stars whose rays pass close to the sun would seem to shift position. When astronomer Arthur Eddington announced the photos showed that the sun’s gravity did indeed bend light, Einstein became the world’s first “science superstar.” Cowen shows how successive generations of physicists have worked to understand gravity, exploring research that showed the universe was expanding (a conclusion Einstein initially resisted); observing this, and the rotation of galaxies, gave physicists their first clues about dark energy and dark matter. Other phenomena touched on include black holes, gravity waves, and even wormholes. Filled with vivid descriptions of cutting-edge work and the scientists behind it, Cowen’s book is fascinating, both a learning experience and a pleasure to read. (May)