Dicke, Robert Henry (1916–1997)

US physicist. In 1964 he proposed a version of the Big Bang theory known as the ‘hot Big Bang’: he suggested that the present expansion of the universe had been preceded by a collapse in which high temperatures had been generated. When Arno Penzias and Robert Wilson announced they had detected an unexpected and relatively high level of radiation at a wavelength of 7 cm/2.8 in, with a temperature of about 3.5 K (−270°C/−453°F), Dicke proposed that this was cosmic black-body radiation from the hot Big Bang.

Dicke carried out experiments to verify the supposition of the general theory of relativity that a gravitational mass is equal to its inertial mass. He was able to establish the equality to an accuracy of one part in 1011. In 1961, he put forward a theory (the Brans–Dicke theory) that the gravitational constant varies with time (by about 10−11 per year). Experiment has not supported this idea.

Dicke was born in St Louis, Missouri, and studied at Princeton and the University of Rochester. From 1946 he was on the staff at Princeton, becoming professor 1957.