When we divide matter into its fundamental, indivisible components, are those particles truly point-like, or is there a finite minimum size?
Imagine that you wanted to know what the matter around you was made of, at a fundamental level. How would you go about figuring out the answer? You might think to approach the problem by taking a piece of that matter and splitting it into small chunks, and then taking one of those chunks and further splitting it into tinier pieces, and so on and so on, until you could split it no longer. When you reached your limit, and found a component that was no longer splitable into anything smaller, that would serve as the best approximation of “fundamental” you could arrive at. Once you discover a component of matter that’s no longer divisible into smaller components, that’s a reasonable way to define fundamental.
For most of the 19th century, we thought that atoms were the fundamental constituents of matter; the Greek word that our work atom derives from, ἄτομος, literally means “uncuttable.” Today, we know that atoms themselves aren’t truly indivisible, but can be split into nuclei and electrons, and that while we cannot split the electron, nuclei can be broken up into protons and neutrons, which can…
