Forces are caused by paticle exchange.
- You can't have instantaneous action at a distance.
- So when particles interact,something must happen to let one particle the other one is there.
- Repulsion: each time the ball us thrown or caught the people get pushed apart. It happens because the ball has momentum. (the ball is seen as the exchange particle)
- .Attraction: each time the boomerang is thrown or caught, the people get pushed together.
These exchange particles are called gauge bosens.
The repulsion between two protons is caused by the exchange of a virtual photon (gauge bosons of the electromagnetic force).
Gauge bosons are virtual particles- they only exist for a very short period…