Exchange Particles

In 1935 Japanese physicist Hideki Yukawa put forward the idea that the interactions/forces between two particles were caused by ‘virtual particles’ being exchanged between the two particles.

He was working on the strong nuclear force which keeps protons and neutrons together and theorised that they were exchanging a particle back and forth that ‘carried’ the force and kept them together. This is true of all the fundamental interactions.

The general term for exchange particles is bosons and they are fundamental particles like quarks and leptons.