Martin Rees is Emeritus Professor of Cosmology and Astrophysics, at the University of Cambridge, the Astronomer Royal, a member of Britain’s House of Lords, and a former President of the Royal Society. The following interview was conducted at Trinity College, Cambridge, by The Conversation’s Matt Warren.
Into space
Q: How big is the universe … and is it the only one?
Our cosmic horizons have grown enormously over the last century, but there is a definite limit to the size of the observable universe. It contains all the things from which light has been able to reach us since the

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