It may be one of the basic building blocks of all matter, but there’s still a lot we have to learn about the proton | BBC Science Focus Magazine

A proton should be one of the simplest objects in physics. It’s a basic building block of all atoms, or, alternatively, the simplest possible atom all by itself, since hydrogen (one positively charged proton plus one negatively charged electron) is still hydrogen when it’s ionised.

Most of the atoms in the Universe are hydrogen, as are most of the atoms in your body. In fact, since electrons are tiny and weigh very little, it’s straightforward to conclude that you are mostly, specifically, protons.

Given all this, you’d think physicists would understand protons very well by now. You would be wrong.