system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] How can a charged particle have mass, but not have size?
gpt
Size is a concept that makes a lot of sense with beer cans, because the impact of quantum mechanics on beer cans averages out to about 0.  The smaller a thing you try to apply a non-quantum concept to the less well the concept is going to work.  Except at absolute zero (0K), all quantum things are always moving, a little.  The math for "quantum position" is statistical, you can have high certainty the object is in a smallish volume of space, but that's just not the same as "position" in the beer can sense of the term.  If "size" is the width of the smallish volume containing the object, that's pretty different from "size" in the beer can sense, and even so there is still some probability the particle is not in the volume marked by its "width".