Gravitational effects in macroscopic quantum systems: a first-principles analysis

We analyze the weak-field limit of General Relativity with matter and its possible quantisations. This analysis aims towards a predictive quantum theory to provide first-principles description gravitational effects in macroscopic systems. includes recently proposed experiments on generation (Newtonian) forces from distributions matter, phenomena like gravity-induced entanglement, cat states, Rabi oscillations, causal orderings events. Our main results include: (i) The demonstration that these do not involve true degrees freedom. (ii) show that, unlike full general relativity, weak gravity is parameterised field theory, i.e., obtained by promoting spacetime coordinates `dynamical' variables. (iii) Quantisation via gauge-fixing leads an effective account for some phenomena, but at price gauge dependence manifests more strongly observables. ambiguity manifestation problem time persists even gravity. (iv) A consistent quantisation theories essential covariant describes also discuss implication our decoherence theories, notion locality vis-a-vis information intriguing possibility solutions can be tested weak-gravity experiments.