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High-energy Physics See also: Mathematics and Physics Introduction The standard model Successes of the standard model ... Recommended references: Books Introduction People have a tendency to wonder what things are made of at least since the Greeks, and undoubtedly much earlier. Artisotle called Thales of Miletus (ca. 585 BCE) the founder of physical science and wrote that Thales believed everything to be made of water. That wasn't so far-fetched, considering water can be solid, liquid, or gas in everyday experience. Artistotle himself, following his teacher Plato, thought that matter was based on four fundamental substances: earth, air, and fire, as well as water. In fact, Aristotle added a fifth essence, "quintessence", that supposedly resided in the celestial world. (The term has been adopted by some modern physicists and repurposed.) Other Greek philosophers took a different approach. Instead of trying to identify the essences of matter, they were content to view matter in terms of the ability to divide it into smaller and smaller units until some ultimate indivisible unit they called the "atom" was reached. Leucippus of Miletus (ca. 450 BCE) and (especially) his student Democritus are recognized for promoting this view. Leucippus and Democritus, of course, weren't that far off, in the view of modern physics. Except that what we now call atoms are known not to be indivisible. In the early 20th century it was recognized that atoms are made of even smaller particles electrons, protons, and neutrons. Somewhat later, in the 1960s, it became apparent that protons and neutrons were themselves composed of smaller particles quarks though electrons remained indivisible. | |
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