October 2, 2021 – Developments in both cosmology and particle physics suggest that our universe may just be one member of an ensemble of universes, termed the multiverse. However, there are many different versions of the multiverse proposal, so it is important to distinguish between these in assessing the plausibility of the notion. In some versions the values of the physical constants may vary across the ensemble, so this could provide a scientific basis for the suggestion that some of the constants are fine-tuned for the existence of observers. The evidence for this comes from numerous unexplained ‘coincidences’ between the constants, a notion which used to regarded as purely philosophical or even theological. But what is the universe fine-tuned for? Is it for complexity or some physical feature (such as the existence of black holes) or is for life or consciousness. And is the multiverse a proper scientific proposal or just philosophical speculation? This depends on the definition of ‘science’ but it is argued that the nature of science has continually changed as our knowledge of the universe has expanded.

Bernard Carr, PhD, is Emeritus Professor of Mathematics and Astronomy at Queen Mary University of London. He was President of the Society for Psychical Research in 2000-2004 and is currently President of the Scientific and Medical Network.

Length: 2 hours and 15 mins