The Quark

Listen on iPlayer (to 25/9/08)

By 1930s it was accepted that everything was made of protons, neutrons and electrons. In the 1960s a plethera of particles were discovered. Some particles decayed quicker than others. Particles were named lambda, p11, k, sigma, x,y, strange - the particle zoo. Murray-Gelman came up with an organising structure - a periodic table of particles. He hypothesised that all particles were a combination of 3 quarks eg Up/Down/Strange quarks eg 2 up quarks + 1 down quark was a proton, 2 down quarks + 1 up quark was a neutron. Experimental evidence for quarks was derived in the 1960s - from Stanford in California - electrons were used to bounce of protons. Protons were shown to made of 3 different particles eg football with 3 ball bearings inside it. If fire a bullet at the football some of the bullets will bounce of some of the ball bearings occassioanly.

Up down strange discovered first then charm, top, bottom. Always held together by the strong force eg 2 and 3 quarks never one quark. Look inside a prison or proton can see the quarks. Marcos Chown (book: Afterglow of creation) cf Tomatoes all quark gluon plasma. Gluon (wikipedia) glue together the quarks in a proton!

Timeline of Particle discovery (wikipedia).