Einstein’s general theory of relativity was, in a real sense, ahead of its time. Einstein was a clear expositor, but in the beginning, few understood him. Even Einstein could not bring himself to believe the full consequences of his discovery: the expansion of the universe, the prediction of black holes. The theory continues to surprise. It is the framework within which cosmologists discuss the Big Bang and formation of structure in the universe (such as the March 2014 announcement of primordial gravitational waves that have been frozen into the microwave background radiation). There are, even now, two huge puzzles that are probably part of this story: the fact that what we think of as normal matter accounts for only 4% of the mass of the universe, with the rest made up of 'dark matter' that does not interact with light or ordinary matter; and 'dark energy' that does not behave like ordinary matter at all, and instead causes the universe to expand.
This book offers a history of general relativity, and also of the figures active in its exploration. Some set about convincing a sceptical world of the inevitability of the existence of black holes; others were more changeable, such as Arthur Eddington, who ultimately used his position and influence to try to suppress the very idea of black holes. The personalities of these practitioners leap from the page. This is a dramatic human story, vividly told, as well as a heroic intellectual journey.