In 1915, Albert Einstein unveiled his masterwork - a theory, in his words, `of incomparable beauty': the General Theory of Relativity. It is sometimes overshadowed - wrongly, argues John Gribbin - by his work of 1905, the Special Theory of Relativity and E = mc². Just over 100 years later, the first direct detection of gravitational radiation is seen as the ultimate proof of the General Theory's accuracy. The General Theory describes the evolution of the Universe, black holes, the behaviour of orbiting neutron stars, and why clocks run slower on Earth than in space. It even suggests the possibility of time travel. In this `beautifully written and highly accessible account of the genesis of a great theory' (Physics World), Gribbin vividly illustrates what an incomparable scientist Albert Einstein really was.