Murray Gell-Mann (1929-2019), US physicist. Gell-Mann proposed a new quantum property in 1953. Called 'strangeness', this property was used to explain the strong nuclear force that holds atomic nuclei together. His later classification system for subatomic particles successfully predicted the existence of a new particle, the omega-minus. With Zweig, in 1964, he postulated quarks as being the fundamental constituents of particles such as protons and neutrons. This work led to Gell-Mann being awarded the 1969 Nobel Prize in Physics.