force carrier photons and magnetic attraction

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Force carrier particles mediate the fundamental forces, and for electromagnetism the force carrier is the photon. That’s what I was taught in high school. I (sort of) understand the idea that these are “virtual” particles though, not real. They mathematically model how the force acts but they aren’t actually there.

Pretending I’m an electron, I can throw a ball (photon) at a bottle (another electron) to knock away (magnetically repel) the bottle. Makes sense. But if I were a proton, then the electron is attracted. How can bouncing a particle (much less a mass less, virtual one) off the electron ever “knock it” towards a positive charge?

In: Physics

3 Answers

Anonymous 0 Comments

Virtual particles are weird, in a lot of ways.

One of those ways is that virtual particles can have properties that no known real particles have.

The specific property necessary in this case is that the virtual particle being exchanged has momentum in the *opposite* direction to the one it’s travelling in – effectively it has negative mass. So when it’s “thrown” the particle throwing it moves in the same direction it does, and when it’s caught it pulls rather than pushing.

Negative mass doesn’t exist, as far as we know, in the world of real particles. But virtual particles aren’t real particles, they’re a particular way of looking at a set of mathematical equations, and thus they’re not bound by the same rules.

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