Quark
The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964. Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until deep inelastic scattering experiments at the Stanford Linear Accelerator Center in 1968. Accelerator experiments have provided evidence for all six flavors. The top quark, first observed at Fermilab in 1995, was the last to be discovered.
Paris in the Belle Époque
The physicist Henri Becquerel (1852-1908), while studying the fluorescence of uranium salts, discovered radioactivity in 1896, and in 1903 was awarded the Nobel Prize in physics for his discovery. Pierre Curie (1859-1906) and Marie Curie (1867-1934) jointly carried on Becquerel's work, discovering radium and polonium (1898). They jointly received the Nobel Prize for physics in 1903. Marie Curie became the first female professor at the University of Paris and won the Nobel Prize for chemistry in 1911. She was the first woman to be buried in the Panthéon.