This short account of elementary particles written for the layman poses the questions: are quarks the fundamental building blocks of matter; what are they like; how many different kinds exist; and can they exist in the free state? What is the ultimate structure of matter? Is it made of atoms, small, simple, indivisible particles, or not? John Dalton's ?chemical atoms? turned out to be composite, composed of an electron cloud and a very small, very dense nucleus. This nucleus, in turn, was found to be composite, made up of protons and neutrons bound together by pions. All three of these (and...

This short account of elementary particles written for the layman poses the questions: are quarks the fundamental building blocks of matter; what are they like; how many different kinds exist; and can they exist in the free state? What is the ultimate structure of matter? Is it made of atoms, small, simple, indivisible particles, or not? John Dalton's 'chemical atoms' turned out to be composite, composed of an electron cloud and a very small, very dense nucleus. This nucleus, in turn, was found to be composite, made up of protons and neutrons bound together by pions. All three of these (and...