>"The Greeks were the originators of this conception. They imagined that 'things' were built out of smaller things, like atoms and molecules. When the atomic th

>"The Greeks were the originators of this conception. They imagined that 'things' were built out of smaller things, like atoms and molecules. When the atomic theory came about, they expected the atoms themselves to have some sort of mass, shape and size, and to be a microcosm of more things. Let's take sand as an example. To the careless eye, sand seems like a fluid, since quantities of it appear to freely merge and split, but on closer inspection, it's just a bunch of tiny objects which can be described as individual `things' interacting with each other. The world of quantum mechanics and quantum field theory introduce a different conception of what things are though. It turns out that elementary particles can't be thought of as individual 'things' which have a volume. In fact, if atoms did have a volume, physics wouldn't work. We would end up with "surfaces" of electrons behaving in an impossible manner and spinning faster than the speed of light. Well then, you say, what if atoms aren't objects with a volume, but points in space? It turns out that this notion isn't easily prone to interpretation either! No one actually knows or understands what a 'point mass' is! It also has a bizarre implication: if indeed we did have volume-less point masses, we obtain something with an infinite density! In theory, the entire universe could be squeezed to a single point!"