3 ms·
> All possible ways you can pop out particles from the vacuum that interacts with your experimental particle and pop back into the vacuum etc. This is a neat s
by frutiger 3y ago
> All possible ways you can pop out particles from the vacuum that interacts with your experimental particle and pop back into the vacuum etc.
This is a neat statement, but really those diagrams are notation for elements in a perturbation expansion series. Nothing in the theory says that these particles actually pop out and actually interact with the incoming/outgoing momenta. In fact they travel off-shell so we know that they cannot be physical.
- l33tman 3y agoIf you're referring to Feynman diagrams, sure in the modern treatment they don't mean what people usually think they mean, but it's also not accurate to state that particles don't pop in/out. It's a simplification for sure, but you really do need to enumerate all the field configurations and there is really no difference from a first principles point of view between your "physical" particles and the "off-shell" excitations. You can argue about the reality of the contributing terms but it sure looks like they're needed or you won't get the right results.