Exploring the limits of no backward in time signalling

Abstract

We present an operational and model-independent framework to investigate the concept of no-backwards-in-time signaling. We define no-backwards-in-time signaling conditions, closely related to the spatial no-signaling conditions. These allow for theoretical possibilities in which the future affects the past, nevertheless without signaling backwards in time. This is analogous to non-local but no-signaling spatial correlations. Furthermore, our results shed new light on situations with indefinite causal structure and their connection to quantum theory.