Percy Williams Bridgman (21 April 1882 – 20 August 1961) was an American physicist who won the 1946 Nobel Prize in Physics for his work on the physics of high pressures. He also wrote extensively on the scientific method and on other aspects of the philosophy of science.
Bridgman entered Harvard University in 1900, and studied physics through to his Ph.D.. From 1910 until his retirement, he taught at Harvard, becoming a full professor in 1919. In 1905, he began investigating the properties of matter under high pressure. A machinery malfunction led him to modify his pressure apparatus; the result was a new device enabling him to create pressures eventually exceeding 100,000 kgf/cm² (10 GPa; 100,000 atmospheres). This was a huge improvement over previous machinery, which could achieve pressures of only 3,000 kgf/cm² (0.3 GPa). This new apparatus led to an abundance of new findings, including a study of the compressibility, electric and thermal conductivity, tensile strength and viscosity of more than 100 different compounds. Bridgman is also known for his studies of electrical conduction in metals and properties of crystals. He developed the Bridgman seal and is the eponym for Bridgman's thermodynamic equations.
Bridgman made many improvements to his high pressure apparatus over the years, and unsuccessfully attempted the synthesis of diamond many times.
His philosophy of science book The Logic of Modern Physics (1927) advocated operationalism and coined the term operational definition. He was also one of the 11 signatories to the Russell-Einstein Manifesto.
Bridgman committed suicide by gunshot after living with metastatic cancer for some time. His suicide note read in part, "It isn't decent for society to make a man do this thing himself. Probably this is the last day I will be able to do it myself." Bridgman's words have been quoted by many on both sides[clarification needed] of the assisted suicide debate.