Oriti continued yet more

the idea of geometrogenesis

The idea of spacetime as a collective, emergent configuration of a large number of quantum gravity building blocks—in particular as a condensate—has been argued for by several authors and from a variety of standpoints. As we will see, this suits well the group field theory framework. So the idea is: continuum spacetime is a collective state of large numbers of GFT building blocks (and perhaps specific to one phase of the system)

In this framework, it turns out that:

We identify the process of quantum spacetime condensation with a known, even if not understood, physical process: namely the big bang singularity. [That is], we identify the coming of the universe, that is of space and time, into being with the physical condensation of the “spacetime atoms”.

And: From this perspective, cosmological singularities, i.e. divergences in curvature invariants in GR, could be a sign of the breaking down of the continuum description of spacetime in a more specific sense than generally understood: they would signal the breakdown of the hydrodynamic approximation of the system of spacetime atoms, and at the same time signal the onset of a phase transition.

Note that on this view (i.e. proposing both the spacetime condensate  and the geometrogenesis), the emergence of spacetime continuum and geometry will be the result of the quantum  properties of the atoms of spacetime. It will be a quantum  phenomenon. Therefore, the order in which the two key limits/approximations needed to recover GR, the semi-classical and the continuum limit, have to be taken is clear: one has first to understand the continuum limit of the quantum system and only then one can take a classical limit and hope to recover a GR-like dynamics.



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