Strife About Complementarity [1953c]

Abstract

If one wanted to condense into a pregnant formula the fundamental achievement of quantum theory, one would say that it has done away with the dualism of matter and force, which had been the leitmotif of scientific thinking since the days of Newton. According to quantum theory, every physical agency partakes of the properties expressed by these two concepts, and its material or dynamical aspects can, so to speak, be conjured up at will by suitably selecting the conditions of observation. Thus, the same agency that usually presents itself to us as a field of electromagnetic force, spread out in space and time, can also appear in the form of a photon, i.e. a quantum of energy and momentum satisfying the conservation laws in the way characteristic for material particles. Again, the agency familiarly known under its aspect of material particle as the electron has dynamical functions of essential importance, e.g. in establishing molecular bonds of the homopolar type, which can only be described in terms of fields of force obeying specific wave-equations.

Property was thus appall’d That the self was not the same; Single nature’s double name Neither two nor one was called. The Phoenix and the Turtle.

Notes

The present essay is a revised version of the author’s contribution, entitled ‘L’évidence de la complémentarité’, to the collective volume, Louis de Broglie, physicien et penseur, Paris 1952.