Bridgman , Percy Williams

(1882–1961) American physicist

Bridgman, the son of a journalist, was born in Cambridge, Massachusetts, and educated at Harvard where he obtained his PhD in 1908. He immediately joined the faculty, leaving only on his retirement in 1954 after serving as professor of physics from 1919 to 1926, professor of mathematics and natural philosophy from 1926 to 1950, and as Huggins Professor from 1950 to 1954.

Most of Bridgman's research has been in the field of high-pressure physics. When he began he found it necessary to design and build virtually all his own equipment and instruments. In 1909 he introduced the self-tightening joint and with the appearance of high tensile steels he could aim for pressures well beyond the scope of earlier workers. At the beginning of the century Emile Amagat and Louis Cailletet had attained pressures of some 3000 kilograms per square centimeter; Bridgman increased this enormously, regularly attaining pressures of 100,000 kg/cm².

Bridgman used such pressures to explore the properties of numerous liquids and solids. In the course of this work he discovered two new forms of ice, freezing at temperatures above 0°C. He also, in 1955, transformed graphite into synthetic diamond. Bridgman was awarded the 1946 Nobel Prize for physics for his work on extremely high-pressures.

He was also widely known as a philosopher of science and in his book The Logic of Modern Physics (1927) formulated his theory of ‘operationalism’ in which he argued that a concept is simply a set of operations. In his 70s Bridgman developed Paget's disease, which gave him considerable pain and little prospect of relief. He committed suicide in 1961.