Posted: Sep 29, 2011 1:32 pm
twistor59 wrote:[
QED perturbation theory is a model par excellence. However it only makes contact with measurements through the in and out states. You can't, with any certainty, ascribe elements of reality to the internals of the calculation, although this helps with visualization and, as Feynman says, organizing the mathematics. It also helps sell books with popularizations of physics.
If you consider only the in and out states as real, then quarks, gluons, W's and Z bosons are never in these in and out states, and by that arguments, they are not real. Ditto with the Higgs boson. We would have to conclude that the majority of the particles in the Standard Model are fictional!
To get the "true" answer, we have to add the contributions of diagrams of all orders. Unfortunately that appears to give infinity.
Each diagram has a probability coefficient, which gets smaller and smaller with higher terms, if the series converge. But that's besides the point. What's important is that the calculation is based on a model. If the calculations then give you predictions that are confirmed by observation, then we take the model to represent reality. That's the way science has always been. I mean, do we ever see a proton or an electron?