[aruanan]

in strong pseudo-magnetic fields electrons orbit in tight circles that bump up against one another, potentially leading to novel electron-electron interactions.

The electrons are what could bump into each other. It was just a poor choice of words to refer to their orbits as things that could interact.

[SonOfDarkSkies]

Oh, you mean the use of the word “bump” [to describe what is probably a very complex interaction]?