Credit: NASA
This dominant cosmological theory suggests the Universe began nearly 13.7 billion years ago, expanding rapidly from a very dense and incredibly hot state. Eventually, stars ignited and galaxies slowly formed. The Big Bang theory has been imporved and advanced especially through NASA’s Cosmic Background Explorer (COBE) and WMAP missions.

Theories of the multiverse suggest that life-containing universes are incredibly rare. We live in one of these, whether by cosmological natural selection or by the consequences of a theory yet to be formulated.


Joseph Silk was born in London, England, studied at the University of Cambridge and Harvard University, and worked for three decades at the University of California, Berkeley. He is Professor of Physics at the Institut d’Astrophysique, Université Pierre et Marie Curie, Paris, Homewood Professor in the Department of Physics and Astronomy, Johns Hopkins University, Baltimore, and Senior Fellow in the Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford.

Joseph Silk has done important early work on inhomogeneities in the cosmic microwave background and how they are influenced by density fluctuations in the matter of the early universe, in particular by a damping effect that bears his name. These were decisive contributions that helped transform cosmology into a high-precision science. He has also made pioneering advances in understanding the nature of dark matter, and explored novel indirect methods for its detection. The latter has inspired very large experiments with new types of telescopes. His studies of galaxy formation and his work on the dynamics of mass loss and the feedback mechanisms from star formation and evolution have formed a very significant basis for subsequent work in this important field. Joseph Silk is also renowned as an excellent lecturer and writer of popular books.