Causal horizon from quantum fluctuations

We propose a simple model of quantum void where the flow of time is deduced directly from quantum fluctuations and the consequent particle-antiparticle creations. Given a certain number of space-like separated pair creation events, assumed to happen all at the same initial time, we show that past and future can be foliated into a sequence of adapted manifolds based on how many events causally influence them. We also give an explicit construction for the simplest case of one space dimension.