"Let us illustrate the problem of signalling with the assistance of the ubiquitous experimenters Alice and Bob. We will place Alice and Bob at some distance apart, and between them there will be a source emitting pairs of entangled particles. To avoid relativistic complications we will assume that Alice, Bob, their detectors, and the particle source are all mutually at rest in an inertial frame (the ‘lab’ frame). Pair after pair of particles are emitted by the source and detected by Alice and Bob's apparatuses, who record their results. Alice and Bob are free to alter the angle of their detectors with each run of the apparatus.