Edward Mills Purcell (August 30, 1912 – March 7, 1997) was an American physicist who shared the 1952Nobel Prize for Physics for his independent discovery (published 1946) of nuclear magnetic resonance in liquids and in solids.[2]Nuclear magnetic resonance (NMR) has become widely used to study themolecular structure of pure materials and the composition of mixtures. Friends and colleagues knew him asEd Purcell.
Born and raised inTaylorville, Illinois, Purcell received hisBSEE inelectrical engineering fromPurdue University, followed by his M.A. and Ph.D. in physics fromHarvard University. He was a member of the Alpha Xi chapter of thePhi Kappa Sigma fraternity while at Purdue.[3] After spending the years ofWorld War II working at theMIT Radiation Laboratory on the development of microwave radar, Purcell returned to Harvard to do research. In December 1945, he discoverednuclear magnetic resonance (NMR) with his colleaguesRobert Pound and Henry Torrey.[4] NMR provides scientists with an elegant and precise way of determining chemical structure and properties of materials, and is widely used in physics and chemistry. It also is the basis ofmagnetic resonance imaging (MRI), one of the most important medical advances of the 20th century. For his discovery of NMR, Purcell shared the 1952 Nobel Prize in physics withFelix Bloch ofStanford University.
Purcell also made contributions toastronomy as the first to detect radio emissions from neutral galactic hydrogen (the famous21 cm line due tohyperfine splitting), affording the first views of the spiral arms of theMilky Way.[5][6] This observation helped launch the field ofradio astronomy, and measurements of the 21 cm line are still an important technique in modern astronomy. He has also made seminal contributions tosolid state physics, with studies of spin-echo relaxation, nuclear magnetic relaxation, and negative spin temperature (important in the development of the laser). WithNorman F. Ramsey, he was the first to question theCP symmetry of particle physics.
Purcell was the author of the innovative introductory textElectricity and Magnetism.[7] The book, aSputnik-era project funded by an NSF grant, was influential for itsuse of relativity in the presentation of the subject at this level. The 1965 edition, now freely available due to a condition of the federal grant, was originally published as a volume of theBerkeley Physics Course. The book is also in print as a commercial third edition, as Purcell and Morin. Purcell is also remembered by biologists for his famous lecture "Life at LowReynolds Number",[8] in which he explained forces and effects dominating in limiting flow regimes (often at the micro scale). He also emphasized the time-reversibility of low Reynolds number flows with a principle referred to as theScallop theorem.
