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London Review of Books

Warp Speed subscriber-only content

Frank Close

  • Travelling at the Speed of Thought: Einstein and the Quest for Gravitational Waves by Daniel Kennefick  Buy this book

When yachts set sail with the tide, or people gather to witness a total eclipse of the Sun, they are trusting in Isaac Newton’s theory of gravity. For more than three hundred years his theory has proved so accurate in describing the universe that it has enabled us not only to predict tides and eclipses, but even to send spaceships to Jupiter, Saturn and beyond. One of Newton’s assumptions is that the effects of gravity are transmitted instantaneously. However, it is worth asking what ‘instantaneous’ means in this context. Since Einstein, the speed of light has been recognised as a natural limit; what, then, is the speed of gravity?

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Frank Close, who teaches at Exeter College, Oxford, is the author of The Void.