Wandered across this Horizon episode on youtube about the physicist Richard Feynman.
Sometimes in life - although I am finding this increasingly more frequent! - you discover someone who you wish you could have known. Richard Feynman, for me, is one of those people.
He won the Nobel Prize for Physics in 1965 for his work on Quantumn Electro-Dynamics (QED, see below) and created Feynman diagrams. He was wonderful at explaining things and I wish he had been my Physics teacher! Exciting and interesting man.
QED is 'the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomena involving electrically charged particles interacting by means of exchange of photons and represents the quantum counterpart of classical electrodynamics giving a complete account of matter and light interaction.' (wiki) Fenyman created a simple diagram to help visualise these interactions. It is wonderfully simple, and I have always thought that true intelligence looks for the simplest answer and can explain things simply. Leonard Susskind, on Feynman, said 'he truly believed that if you couldn't explain something simply you didn't understand it'.
Time is on the vertical axis and space is on the lateral. As I understand it, as the two electrons move close to each other and eventually repel each other due to them both having the same charge. As they do, they exchange a photon.