Localization and Causality for a free particle

Abstract

Theorems (most notably by Hegerfeldt) prove that an initially localized particle whose time evolution is determined by a positive Hamiltonian will violate causality. We argue that this apparent paradox is resolved for a free particle described by either the Dirac equation or the Klein-Gordon equation because such a particle cannot be localized in the sense required by the theorems.

9 pages,no figures,new section added

References in corpus (1)

• Photon position operators and localized bases

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