Feynman’s Path Integral Method

Abstract

Richard Feynman, who seemed always to be able to create his own physical world, produced an alternative version of quantum theory from the conventional one. Although it is formally quite different from the conventional one, it is completely consistent with it. What it does do is conjure up a different set of images, which open up interesting new insights. Nowhere does it invoke probabilities, nor does it suggest collapse of the wave function on measurement. Rather, it reaches out to encompass all space. It talks not about particles but about paths, which carry phase from point to point. We illustrate it with a familiar example from geometrical optics.

The subject is fully explained in Feynman’s book Q.E.D. (Princeton University Press, Princeton, NJ, 1985). Our purpose is merely to give an illustration of the ideas behind it.