Physics in Real and Counterfactual Universes

  • Speaker
  • Martin Rees, Ph.D.Astronomer Royal, Fellow of Trinity College, Emeritus Professor of Cosmology and Astrophysics , University of Cambridge
Date & Time


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Simons Foundation Lectures are free public colloquia related to basic science and mathematics. These high-level talks are intended for professors, students, postdocs and business professionals, but interested people from the metropolitan area are welcome as well.
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Over 13.8 billion years, the material emerging from the big bang has transformed into our complex cosmos. But what would the universe look like if a different set of forces and cosmological parameters shaped its evolution?

In this lecture, Martin Rees will describe how the emergence and properties of galaxies, stars, planets and life depend on a few key numbers: the ‘constants’ of microphysics and the parameters that describe our expanding universe. According to some cosmologists and string theorists, domains may actually exist where these constants have different values. It is therefore interesting to explore what range of values would permit the emergence of complexity. Even those who are allergic to this concept of a multiverse may find their insight enhanced by exploring ‘counterfactual’ universes, just as some historians speculate about ‘counterfactual’ scenarios such as what would have happened if the British triumphed during the American Revolutionary War.

About the Speaker

Rees is an astrophysicist and cosmologist, mainly based in Cambridge, who has contributed to the study of galaxy formation, black holes and many phenomena in high-energy astrophysics.

He is a foreign associate of the National Academy of Sciences, the Russian Academy of Sciences, the Pontifical Academy, the Japan Academy and several other academies. He belongs to the British House of Lords and was president of the Royal Society between 2005 and 2010.

In addition to his research publications, Rees has written and lectured extensively for general audiences. His ten books include “Just Six Numbers,” “Our Cosmic Habitat,” “Gravity’s Fatal Attraction” and the recently-published “On the Future: Prospects for Humanity.”

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