> the photon I shine on my wall with a flashlight did a few orbits around Jupiter too This is a very confusing way to essentially say that an integral of exp(−

> the photon I shine on my wall with a flashlight did a few orbits around Jupiter too This is a very confusing way to essentially say that an integral of exp(−iS) is taken over all possible paths for the action S. Your flashlight's photons don't literally do a few orbits around Jupiter. In fact, photons are quantum objects (not billiard balls) and they are "smoothed out" over spacetime, meaning they don't really have paths to take in the first place.