All the matter that is around you is made up of atoms. That's a pretty well-known fact at this point, and, while it gets increasingly interesting and strange the more you think about it (the properties of each different element are just functions of how many protons it has, which is pretty wild), an atom is not the fundamental unit of matter, as its name, derived from the Greek atomos, which means indivisible, would suggest. No, the physicist John Dalton disabused us of that notion back in the 1800s, and since then we have learned that an atom consists of three constituent particle types: protons, neutrons, and electrons. Hans Geiger, Ernest Marsden, and Ernest Rutherford came up with the model of an atom with those pieces (as covered in the very first Fizzix Phriday blog post), and that most of the mass of an atom...

Matter. It's basically everything. Anything you can see and touch (except holograms), and some things that you can't see or touch, is matter. There's plain old boring matter, which is all the things you see around you all the time, and is composed of atoms you see on the periodic table. But then there's all that cool weird matter (not necessarily strange or exotic matter, because those are actual, real names of types of matter). Since you're already probably pretty familiar with prosaic matter, having been interacting with it all your life, let's talk about some of the more interesting matter.

Let's begin with a journey through time (and space, if you live any distance from Cambridge). The year is 1909, nearly seventy years since the death of John Dalton, the physicist who pioneered atomic theory. It's a little over ten years since Sir Joseph John Thomson (J.J. Thomson—not to be confused with the other J.J. Thomson, who was a philosopher) discovered the electron, and created the "plum pudding" model of an atom. This model stated that atoms were a more or less homogeneous mix of positively-charged and negatively-charged particles (protons and neutrons respectively). Electrons were the negatively-charged ones, because Ben Franklin said so in the eighteenth century (simplification, and possibly slightly farcical). Atoms were more of less the coolest kid in town when it came to physics, but scientists still didn't really know all that much about them—the "plum-pudding" model was mostly a wild guess.