If the idea of an atom seemed crazy -- being so minute it was undetectable for centuries -- imagine how it would seem to then talk about an even smaller, subatomic particle. Described as an “elementary particle,” quarks are believed to be constituent parts of atomic particles (i.e., protons, neutrons and electrons). When the idea was introduced in the 1960s, it was seen by some as merely an abstract concept to help explain things we didn’t understand
. Over the following decade, further research and mounting evidence supported the quark model, finally convincing people of its validity.