# Chung ## Infrared Divergence in Quantum Electrodynamics \[Links: [Inspire](https://inspirehep.net/literature/49635)\] \[Abstract: The [[0295 Infrared divergences in scattering amplitude|infrared divergences]] of quantum electrodynamics are eliminated to all orders of perturbation theory in the matrix elements by an appropriate choice of initial and final soft photon states. The condition for this cancellation restricts these states to representations of the canonical commutation rules which are unitarily inequivalent to the usual Fock representation.\] # Epstein, Glaser, Jaffe ## Nonpositivity of the energy density in quantized field theories \[Links: [DOI](https://doi.org/10.1007/BF02749799)\] \[Abstract: It is shown that a positive definite local energy density is incompatible with the usual postulates of local field theory. The question whether it can be bounded below is briefly discussed but not solved.\] # Penrose ## Gravitational Collapse and Space-Time Singularities \[Links: [DOI](https://doi.org/10.1103/PhysRevLett.14.57)\]