Feynman Path Integral

Because it sums over infinitely many possibilities, the path integral never allows faster-than-light paths, which also removes the need to rely on the Dirac equation. It even addresses a problem in quantum field theory: by integrating over the interactions of infinitely many excitable particles, it yields a meaningful probability amplitude. Yet while it can handle infinitely many paths, the problem may not be fully solved, since an event built from infinitely many events can again give rise to infinitely many events. To push past this, Feynman introduced one further idea.