Dennis Scientis — Wikipedia

Dennis William SIAHOU SCIMA ( November 18, 1926 – December 18, 1999 ) is a British physicist who, through his own works and those of his students, played a major role in the development of British physics after the Second World War. It is considered one of the fathers of modern cosmology ^{[ first ] , [ 2 ]} . He was a member of the Royal Society .

Sciama was born in Manchester in England. He is of Egyptian Jewish origin on the side of his father and of Egyptian Jewish origin and Syrian Jewish on the side of his mother ^{[ 3 ]} . His family name was initially spelled “Shama.”

Sciama obtained his PHD in 1953 at the University of Cambridge under the supervision of Paul Dirac, with a dissertation on the principle of Mach and inertia. His work later influences the formulation of the theories of tensor-scalar gravitation.

He teaches in Cornell, at King’s College in London, Harvard and the University of Texas in Austin, but spent most of his career in Cambridge (1950s and 1960s) and at the University of Oxford (1970s and early 1980s). In 1983, he moved from Oxford to Trieste, becoming professor of astrophysics at International School of Advanced Studies (Sissa), and consultant for the International Center for Theoretical Physics.

During the 1990s, he shared his time between Trieste (with a residence in Venice) and Oxford, where he was a visitor professor until the end of his life. His main home remains his house in Park Town, Oxford (in) .

Sciama relies on his extended knowledge of physics to make fruitful connections between many subjects in astronomy and astrophysics. He publishes on radio-astronomy, astronomy of X-rays, quasars, anisotropy of the cosmological diffuse background, the interstellar and intergalactic environment, particle physics and the nature of dark matter. Its most important work concerns general relativity, with and without quantum gravity, and black holes. He contributed to relaunch the classic relativist alternative to the general relativity called gravity of Einstein-Cartan.

At the start of his career, he supported Fred Hoyle’s stationary state theory and worked with Hoyle, Hermann Bondi and Thomas Gold. When the evidence against the theory of the stationary state, for example the cosmological diffuse background, accumulated in the 1960s, Sciama abandoned it.

During his retirement, Sciama defends a theory of dark matter which appeals almost exclusively to a heavy neutrino, now abandoned.

Many important astrophysicists and cosmologists from our time are preparing their doctorate under the supervision of Sciama, including in particular:

Sciama strongly influences Roger Penrose, who dedicates his book The Road to Reality In memory of Sciama. The group he led in the 1960s in Cambridge (which includes Ellis, Hawking, Rees and Carter) has a lasting influence.

Sciama was elected member of the Royal Society in 1982. He is also an honorary member of the American Academy of Arts and Sciences, the American Society of Philosophy and the Academy of Lycèens of Rome. He is president of the International Society of General Relativity and Gravitation from 1980 to 1984.

In 1959, Sciama married Lidia Dina, a social anthropologist, with whom he had two daughters.

His work in Sissa and the University of Oxford lead to the creation of a series of conferences in his honor, the Dennis Sciama Memorial Lectures ^{[ 4 ]} . In 2009, the Cosmology Institute of the University of Portsmouth chose to appoint its new building in its honor. ^{[Quote required]}

• 1959. The Unity of the Universe . London: Faber & Faber.
• 1969. The Physical Foundations of General Relativity . New York: Doubleday. Science Study Series. Short (104 pages) and clearly written non-mathematical book on the physical and conceptual foundations of General Relativity. Could be read with profit by physics students before immersing themselves in more technical studies of General Relativity.
• 1971. Modern Cosmology . Cambridge University Press.
• 1993. Modern Cosmology and the Dark Matter Problem . Cambridge University Press.

• (in) George Ellis, Antonio Alcanza et John Miller, The Renaissance of General Relativity and Cosmology : A Survey to Celebrate the 65th Birthday of Dennis Sciama , Cambridge University Press, 2005 , 344 p. (ISBN  978-0-521-02108-1 , DOI  10.1017/CBO9780511622724 , Online presentation , read online ) .
• (in) George F. R. Ellis, ‘ Obituary: Dennis Sciama (1926-99) » , Nature , vol. 403, n ^O 6771, February 17, 2000 , p. 722 .