Relativistic Quantum Mechanics & Localized Particles

[andresB]

He said that this was down to the fact that we should be considering multi-particle states in relativistic situation, before introducing Fock-space states.

There have been already a lot of answers, I only want to quote the introduction of "quantum electrodynamics" by Beretetskii-Lifshitz-Pitaevskii

 

[vanhees71]

But if you take 4D Fourier transforms then the N-point Green's functions get N times, and can for N>2 no longer be interpreted in terms of inner products of multiparticle states (where there is one time only but multiple space coordinates).

Of course not. The QFT formalism automatically takes care of the Bose/Fermi (anti-)symmetrization.