Science in the Contemporary World An Encyclopedia

Since World War II, nuclear physicists haveused cloud chambers and then particle acceleratorsto smash particles into ever smallerparticles, tracking the subatomic particlesthat persist briefly before decaying. (SeeParticle Accelerators; Particle Physics). In1953, the physicist Murray Gell-Mann proposedthe property of strangeness to organizethe numerous subatomic particles thathad been discovered. In 1964, Gell-Mannproposed a new type of fundamental matter,called quarks and anti-quarks, as formingsubatomic particles. Quark theory is nowpart of the standard model that attempts tocombine the four basic forces (weak nuclearforce, strong nuclear force, electromagnetism,and gravity). (See Gell-Mann, Murray;Neutrinos). Another foundation of the standardmodel came in the 1950s through thework of Richard P. Feynman