Quarks are one of six hypothetical particles that are believed to form the basic pieces of the elementary particles called hadrons. Hadrons are the proton, neutron, and pion. The quark concept was proposed in 1963 by two different researchers, American physicists Murray Gell-Mann and George Zweig. The term quark was taken from Irish writer James Joyce’s Finnegan’s Wake. At first quarks were classified as three different kinds: up, down, and strange.
The proton, for example is believed to be constituted of two up quarks and one down quark. Later theorists came up with a fourth quark. In 1974 the fourth quark named “charm” was experimentally confirmed. Therefore a fifth and sixth quark called bottom and top, were hypothesized for symmetry reasons.
Experimental evidence for the bottom quark was obtained in 1977. The top quark wasn’t confirmed till 1995, when two teams of physicists announced they had found and measured the top quark. Each kind of quark has its antiparticle, and each kind of quark or antiquark comes in three types of colors. Quarks can be either red, blue, or green, while antiquarks can be either antired, antiblue, or antigreen.
These quark and antiquark colors have nothing to do with the colors seen by the guman eye. These colors represent a quantum property. When combining to form hadrons, quarks and a Bibliography:
