dipper@utastro.UUCP (Debbie Byrd) (01/18/86)
There are particles in our universe even tinier than atoms. More on the world of particles -- after this. January 18 The World of Particles Since the time of the ancient Greeks, a search has gone on for the smallest particles of nature -- tiny building blocks of matter that combine to create all things. The word "atom" was used by the Greeks to describe this most elementary particle -- and most of us learned in school that all matter is built of atoms. That's still true. But what we call atoms are not nature's most fundamental building blocks. Huge machines -- sometimes called "atom smashers" -- but known to physicists as "particle accelerators" -- are used to discover and investigate a vast variety of smaller particles in nature. There are literally hundreds of such particles -- so many that some are known by Greek letters only -- and some only by number. Most elementary particles are short-lived and not found in ordinary matter. They exist only fleetingly before decaying into the more familiar particles that join together to create matter as we know it. It has been known for some time that atoms are made of electrons orbiting a nucleus -- and that the nucleus of an atom contains entities known as protons and neutrons. But protons and neutrons can be broken down into still smaller particles -- first proposed in 1963 -- called quarks. The existence of quarks was proven in the late 1960s in a series of experiments in a California particle accelerator. Physicists are still exploring their properties -- but some believe that quarks are truly elementary particles -- pointlike -- indivisible -- matter on the smallest scale -- that combines to create the universe we know. Script by Deborah Byrd. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin