“There are strong reasons for believing that space goes on beyond the limits of our observational horizon. There are strong reasons because if you look in opposite directions, conditions are the same to within one part in 100,000. So if we are part of some finite structure then, if the gradient is so shallow, it is likely to go on much further.”

British cosmologist and astrophysicist

Martin John Rees, Baron Rees of Ludlow, is a British cosmologist and astrophysicist. He served as the fifteenth Astronomer Royal from 1995 to 2025, was Master of Trinity College, Cambridge, from 2004 to 2012, and led the Royal Society as president from 2005 to 2010. His work has been recognised with several physics honours, including the Wolf Prize in Physics in 2024 for fundamental contributions to high-energy astrophysics, galaxies and structure formation, and cosmology. He is known for writing and speaking about the universe at its largest scales, from the growth of galaxies to the forces that shape cosmic structure.