Smashing electrons together has been less explored compared to protons and neutrons, but electron-positron colliders like LEP have provided valuable insights into particle physics due to their cleaner interactions. While electron-electron collisions are possible, they yield less interesting results and require significantly higher energy levels, making them less practical. Neutrons cannot be accelerated in colliders, limiting their study to secondary collisions from other particle interactions. Fixed-target electron experiments serve as a lower-energy alternative for studying electron-electron and electron-nucleus collisions. Overall, electron collisions present unique challenges and opportunities in particle physics research.
