Guenter Ahlers received his B.A. degree in chemistry from the University of California at Riverside in 1958 and a Ph.D. in physical chemistry from the University of California at Berkely in 1963. In 1963 he became a Member of Technical Staff at Bell Laboratories in Murray Hill, N.J. There he worked on critical phenomena near the lambda point in liquid helium and near magnetic phase transition, and on superfluid hydrodynamics. In 1970 he began research on Rayleigh-Bénard convection in liquid helium that led to the experimental observation of chaos in a fluid-mechanical system. In 1979 Ahlers moved to the University of California, Santa Barbara, where he studied pattern formation in convection and Taylor-vortex flow, and turbulent Rayleigh-Bénard convection. He and his co-workers published about 270 papers in the Journal of Fluid Mechanics, Physics of Fluids, Physical Review A, B, and E, Physical Review Letters, and elsewhere. Ahlers became a Fellow of the APS in 1971 and of the AAAS in 1990. He received the IUPAP Fritz London Memorial Award in low-temperature physics in 1978, the Alexander von Humboldt Senior US Scientist Award in 1989, and the APS fluid-dynamics prize in 2007. In 1998 he was a Guggenheim Fellow. He was elected to the National Academy of Sciences in 1982 and became a Fellow of the American Academy of Arts and Sciences in 2004.
Convection in a fluid heated from below, known as Rayleigh-Bénard convection, is an important turbulent process that occurs in the sun, planetary atmospheres, industrial manufacturing, and many other places. Physicists and engineers have made much progress in understanding this phenomenon in simple laboratory geometries, but still have a way to go before they are able to extrapolate to the extreme conditions often encountered in nature.