When calculating the dynamics of a particle, we can use Feynman's path integral to determine the observables involved. This integrates over every possible path that the particle can take. We can even use it to calculate the vacuum energy of empty space. Now what happens to that vacuum energy calculation at a particular point if there is a nearby particle. Since the path integral calculates every possible path, some of those paths will be through the nearby particle. So I wonder what happens to the vacuum energy calculation if a nearby particle is introduced? Does it take longer for process than compared to no nearby particle? Does it take less space to get the same effect? As I understand it, a particle can influence the surrounding vacuum by polarizing the virtual particles and producing a screening effect so that other particles don't feel the full strength of a charge, for example. So I wonder if the reverse is true. Does a nearby particle influence calculations of the vacuum?