Physicists Murray Gell-Mann and George Zweig, working separately, each posed the possibility of the quark in 1964. Its unusual name was chosen by Gell-Mann, who saw the word "quark" used as a nonsensical term in James Joyce's Finnegans Wake (1939) and liked the sound of it.
Quarks are fundamental particles that make up everything in the universe. In all, there are six brands of quark, usually paired off and called up/down quarks, charm/strange quarks and top/bottom quarks. The top quark, though theorized for decades prior, was not discovered until 1995. Quarks have a fractional charge, as opposed to the +1 or -1 electrical charge carried, respectively, by the proton and neutron [source: The Particle Adventure]. They can't be seen, even with the most powerful of telescopes. Interestingly, their existence is only confirmed by deduction. They can't be isolated for study, but we know they exist because calculations that assume and depend on their existence are correct when used in experimentation [source: Stanford University].
Zweig is a Russian-born physicist but grew up in the United States, where he got his doctorate from the California Institute of Technology in 1963. In the years leading up to his quark discovery, he worked at the European Organization for Nuclear Research (CERN).
Gell-Mann is a Nobel Prize winner, who took the award in 1969 for his work on what he called the Eightfold Way, which helped scientists classify and organize particles in the subatomic realm. He realized that neutrons and protons could each be made up of three particles that had fractional charges. Those particles are quarks. It meant that the neutron and proton were no longer elementary particles -- they could be broken further down into quarks. Gell-Mann says among the difficulties he faced was getting people to believe in the existence of quarks, because they could not be seen: they were confined inside the protons and neutrons and couldn't be pulled out for examination one at a time [source: Kruglinski].
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