[aruanan]

For example, in strong pseudo-magnetic fields electrons orbit in tight circles that bump up against one another, potentially leading to novel electron-electron interactions. Says Crommie, “this is the kind of physics that physicists love to explore.”

But the kind of English that grammarians love to deplore.

[SonOfDarkSkies]

IIRC that usage is correct because there are more than two circles bumping (i.e. "each other" where there are only two, "one another" where there are more than two)?

Have I got it wrong?