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TRIUMF - Physics 101: What is our world made of?

What is everything made of? What is the smallest possible piece of matter? Twenty-three[democritos] centuries ago a Greek philosopher, Democritos, came up with the idea that all matter is made of "atoms". Imagine taking a piece of iron, for instance, and chopping it in half, then chopping one of those pieces in half, and so on. Could you keep this up indefinitely? Democritos believed you could not - you would eventually have the smallest possible piece of iron, and he called this an atom. He imagined atoms as little spheres hooked to each other.
Given the complete lack of the scientific tools that we enjoy today, Democritos' insight is astounding. Today we know that atoms do indeed exist, and there are about 100 different kinds of atoms (we call them the chemical elements, such as oxygen, silicon, and copper). We know that almost everything we see around us is made of "molecules" - groups of atoms joined together in specific patterns.

Molecules are groups of joined atoms. But in the past 100 years we have discovered another quite remarkable fact: atoms themselves are made out of even smaller particles! The study of these particles and their properties is called subatomic physics, and this is the kind of science we do at TRIUMF.

The name TRIUMF, incidentally, comes from TRI-University Meson Facility. ("TRI" is a prefix meaning "three", though by now there are five full partner universities and six associate-member universities involved; a meson is a special kind of subatomic particle that we can produce in large numbers at TRIUMF - billions of them per second.)