- TL;DR Summary
- Superfluid vacuum theory or BEC vacuum theory is one candidate theory of quantum gravity but from the description in wikipedia it is not clear how gravity becomes a force it just says that curvature is density difference in virtual particles. So how does gravity becomes a force?
It has been hypothesized by quantum field theory that the vacuum is not empty due to the energy time uncertainity relationship. Instead it is filled with a sea of virtual particles popping in and out of existence and renormalized to the observed value we see today in experiments like the casimir effect and observations like dark energy. One possible mechanism of unifying gravity and the standard model of particles is to claim that gravity is an emergent phenomena of the quantum vacuum. This is called the superfluid vacuum theory where the quantum vacuum acts as a superfluid of virtual particles. Curvature is represented as density of the superfluid. To me it is not clear how gravity becomes a force in this picture. I know there are a lot of versions of this theory. Do these versions vary on how gravity emerges as a force from the dynamics of the superfluid?