Multiple universes used to be pure speculation. Today, most cosmologists are sure they exist, perhaps in many forms and almost certainly in vast numbers, perhaps infinite in size and scope. What caused multiple universes to go from far-out guesswork to conventional wisdom? And does anyone challenge the new belief?
Martin John Rees, Baron Rees of Ludlow is a British cosmologist and astrophysicist. He served as Astronomer Royal and Master of Trinity College, Cambridge. Rees was President of the Royal Society.