Space-Time Symmetries in Quantum Physics

UMBERTO LOMBARDO, G. Giuliani, Yifei Niu

Gordon Walter Semenoff

Cristian López, Olímpia Lombardi

ming Cheng

Where does Heisenberg’s uncertainty principle come from? We show that it requires two physical inputs, neither sufficient alone. Space-time symmetry decides which observables are conjugate: momentum generates translations, so [x,p] is constant. Quantum structure, namely the complex structure of Hilbert space, makes observables into generators, so conjugate observables do not commute. The two combine as a non-trivial central extension, the Heisenberg group. At this level the physical and mathematical origins coincide. The uncertainty principle is the Cauchy–Schwarz inequality on the Kähler state space, which is equivalently the quantum Cramér–Rao limit on detecting a symmetry transformation. Phase-space geometry alone is not an origin, and infinite dimension is the price of the canonical bound, not its source.

Michael E. Kellman

It is argued that the standard quantum mechanical description of the Bell correlations between entangled subsystems is in conflict with relativistic space-time symmetry. Proposals to abandon relativistic symmetry, in the sense of explicitly returning to an absolute time and preferred frame, are rejected on the grounds that the preferred frame is not empirically detectable, so the asymmetry is an unsatisfactory feature in physical theory. A "symmetric view" is proposed in which measurement events on space-like separated entangled subsystems are connected by a symmetric two-way mutual influence. Because of this reciprocity, there is complete symmetry of the description: Einsteinian relativity of simultaneity and space-time symmetry are completely preserved. The nature of the two-way influence is considered, as well as the possibility of an empirical test.