Any particle, such as a proton or neutron, in the nucleus of an atom. The center of an atom, consisting of one or more protons and associated neutrons. A process by which a systems changes from one state to another state with different properties, as a result of small changes in temperature or pressure. Not seen under everyday conditions, but produced at high temperatures or in reactions between atoms. Made of two up quarks and one down quark, a proton has a positive charge.
Quarks combine with gluons to make the protons and neutrons that make up every atom in the universe.
The basic characteristic that differentiates the six varieties of quark. Thought to have existed a few millionths of a second after the Big Bang, before matter cooled and organized into hadrons and atoms. Also thought to exist at the centers of neutron stars. RHIC The Relativistic Heavy Ion Collider, a physics research machine at Brookhaven National Laboratory. Will collide two beams of atomic nuclei at 99.95 percent the speed of light.