Acausal behaviour in quantum electrodynamics

Oscar Wallace Greenberg

Piotr Kosiński

Acausal behaviour of solutions to the free Salpeter equation is considered. It is shown that the formal properties of solutions suggest the acausal propagation of quantum phenomena. On the other hand, the same properties of solutions applied to macroscopic phenomena can be explained without appealing to the notion of acausality.

Julian Schwinger, J. C. Polkinghorne

M. I. Shirokov

Causality, in the sense of finiteness of the velocity of propagation of signals, is discussed for quantum electrodynamics. The paper proposes an appropriate quantum-mechanical criterion for causality. According to this criterion local observables like the field strengths E(x), H(x) and the current density j/sub ..mu../(x) behave causally. However, the theory contains quantities (like the electron number density) which exhibit macroscopic acausality. The reason for this result is discussed in a theory where the usual causality condition, i.e., local commutativity of the operators A/sub ..mu../ and psi, is satisfied. (AIP)

Edwin Albert Power, I. Saavedra

Abstract The problem of causality in non-relativistic scattering where a bounded region of non-linear interaction occurs is re-examined in the context of a paper by Ebel. In the model considered it is shown that the acausal behaviour cannot be accounted for in the straightforward manner that is possible for an energy-dependent but linear potential which gives rise to a similar R-matrix.

Docteur De, L’université De Grenoble, Spécialité Physique +8 more