Brian David Josephson, FRS, is a Welsh physicist. He became a Nobel Prize laureate in 1973 for the prediction of the eponymous Josephson effect. As of late 2007, he was a retired professor at the University of Cambridge, where he is the head of the Mind–Matter Unification Project in the Theory of Condensed Matter (TCM) research group. He is also a fellow of Trinity College, Cambridge.

Brian Josephson attended Cambridge University, where he gained a BA in 1960. As an undergraduate he published a paper in which he calculated a thermal correction to the Mössbauer effect that reconciled previously different measurements of gravitational red shifts reported by teams in the US and UK. After completing his undergraduate degree he continued to study at Cambridge, and in 1964 was awarded his PhD in physics. In the 1970s he learned Transcendental Meditation. Josephson became a fellow of Trinity College, Cambridge in 1962 before moving to the United States to take a position as Research Assistant Professor at the University of Illinois. He returned to Cambridge University in 1967 as an Assistant Director of Research at the Cavendish Laboratory and then a professor of physics in 1974, a position he retained until his retirement in 2007.

Since 1983 Josephson has been appointed a Visiting Professor at various institutions including the Wayne State University in 1983, the Indian Institute of Science in 1984 and the University of Missouri-Rolla in 1987. Josephson has been a member of the Theory of Condensed Matter (TCM) Group, a theoretical physics group at the Cavendish Laboratory, for much of his research career. While working at TCM group he was jointly awarded the Nobel Prize in Physics in 1973 while still only a Reader in Physics. He shared the award with Japanese physicist Leo Esaki and American physicist Ivar Giaever, who each received 1/4 of the prize, with 1/2 going to Josephson. Unusually, along with Josephson, neither Esaki nor Giaever held professorships at the time of the award. It is rare that academics ranked below professors win the prestigious prize. In addition and also unusually, each of the three performed the relevant research prior to being awarded his PhD.

Josephson also directs the Mind–Matter Unification Project in the TCM Group. He currently sits on the Advisory and Editorial Board of NeuroQuantology: An Interdisciplinary Journal of Neuroscience and Quantum Physics. Josephson has received many honors and awards, including the New Scientist award, the Fritz London Memorial Prize, the Nobel Prize for Physics, the Guthrie Medal (Institute of Physics), the Elliott Cresson Medal (Franklin Institute) the Hughes Medal (Royal Society), the Holweck Prize (Institute of Physics and French Institute of Physics), the Faraday Medal (Institution of Electrical Engineers), Sir George Thomson Medal (Institute of Measurement and Control), and the Medal of the town of Marseilles.