A. P. Balachandran (Syracuse University)
Title: Causality in Quantum Field Theory
Abstract: In 1993 , Rafael Sorkin argued that standard quantum measurement theory and relativistic causality are not compatible because of the existence of entangled quantum states . He showed this by devising experiments using entangled states which transmit information to spacelike distances.It was only recently that Bostelman et al. showed that Rafael’s causality problem gets resolved in Local Quantum Field Theory. This talk presents an interpretation of their result developed during joint discussions with colleagues. It emerges naturally from earlier work by Stueckelberg , Bogoliubov , and Epstein and Glaser . The discussion also shows the resolution of an old causality problem of Fermi in atomic physics. The talk also argues that if the local algebras in a future quantum theory of gravity shares certain universal properties with those of the current Local Quantum Physics, there is a natural quantum implementation of diffeomorphisms. This observation is based on an important theorem of Connes and Stormer which is also explained.