Perhaps no amount of heat can reduce quarks into smaller pieces, and quarks are the end of the road.
1964, applied by U.S. physicist Murray Gell-Mann (b.1929), who said in correspondence with the editors of the OED in 1978 that he took it from a word in James Joyce's "Finnegans Wake" (1939), but also that the sound of the word was in his head before he encountered the printed form in Joyce. German Quark "curds, rubbish" has been proposed as the ultimate inspiration [Barnhart; Gell-Mann's parents were immigrants from Austria-Hungary]. George Zweig, Gell-Mann's co-proposer of the theory, is said to have preferred the name ace for them.
Any of a group of elementary particles supposed to be the fundamental units that combine to make up the subatomic particles known as hadrons (baryons, such as neutrons and protons, and mesons). There are six different flavors (or types) of quark: up quark, down quark, top quark, bottom quark, charm quark, and strange quark. Quarks have fractional electric charges, such as 1/3 the charge of an electron. See Note at elementary particle. See Table at subatomic particle.
Note: No quarks have been seen in the laboratory because, according to current theory, they cannot exist as free particles.