Editing Huygens–Fresnel principle (section)

==Feynman's path integral and the modern photon wave function==
Huygens' theory served as a fundamental explanation of the wave nature of light interference and was further developed by Fresnel and Young but did not fully resolve all observations such as the low-intensity [[double-slit experiment]] first performed by G. I. Taylor in 1909.  It was not until the early and mid-1900s that quantum theory discussions, particularly the early discussions at the 1927 Brussels [[Solvay Conference]], where [[Louis de Broglie]] proposed his de Broglie hypothesis that the photon is guided by a wave function.<ref>{{cite book|last1=Baggott|first1=Jim|title=The Quantum Story|url=https://archive.org/details/quantumstoryhist00bagg|url-access=limited|date=2011|publisher=Oxford Press|isbn=978-0-19-965597-7|page=[https://archive.org/details/quantumstoryhist00bagg/page/n136 116]}}</ref>  

The wave function presents a much different explanation of the observed light and dark bands in a double slit experiment. In this conception, the photon follows a path which is a probabilistic choice of one of many possible paths in the electromagnetic field.  These probable paths form the pattern: in dark areas, no photons are landing, and in bright areas, many photons are landing.  The set of possible photon paths is consistent with Richard Feynman's path integral theory, the paths determined by the surroundings: the photon's originating point (atom), the slit, and the screen and by tracking and summing phases. The wave function is a solution to this geometry.  The wave function approach was further supported by additional double-slit experiments in Italy and Japan in the 1970s and 1980s with electrons.<ref>{{cite web|last1=Peter|first1=Rodgers|title=The double-slit experiment|url=https://physicsworld.com/a/the-double-slit-experiment/|website=www.physicsworld.com|publisher=Physics World|access-date=10 Sep 2018|date=September 2002}}</ref>