Radical new foundations for both quantum theory and space-time

[RUTA]

It would be news if they could derive mass, space and time from something else more primitive, e.g., Vigor -- haha, love that. Otherwise, they're looking at something like Einstein's equations which tell you how the spacetime metric is to be "self-consistently" related to the stress-energy tensor.

 

[marcus]

It might help to get a more direct look at what we're talking about. I'll quote from Wolfgang Wieland's July paper. To get it without the link, google "wieland new action". As far as I can see there is no spacetime manifold here, and no spacetime metric. And yet analogs of several tools familiar with traditional GR analysis are present.
==quote http://arxiv.org/pdf/1407.0025v1.pdf abstract==
New action for simplicial gravity in four dimensions

We develop a proposal for a theory of simplicial gravity with spinors as the fundamental configuration variables. The underlying action describes a mechanical system with finitely many degrees of freedom, the system has a Hamiltonian and local gauge symmetries. We will close with some comments on the resulting quantum theory, and explain the relation to loop quantum gravity and twisted geometries. The paper appears in parallel with an article by Cortês and Smolin, who study the relevance of the model for energetic causal sets and various other approaches to quantum gravity.
==endquote==
I would suggest reading the paper before jumping to the conclusion that time here is some traditional GR observer's clock time, or that the Hamiltonian conforms to conventional preconceptions.
==quote http://arxiv.org/pdf/1407.0025v1.pdf page 24==
The relevance of the model
The action (50) describes a system of finitely many degrees of freedom propagating and interacting along the simplicial edges. The system has a phase space, local gauge symmetries and a Hamiltonian. What happens if we quantize this model? Do we get yet another proposal for a theory of quantum gravity? Recent results [23, 27, 36, 58] point into a more promising direction and suggest a convergence of ideas: The finite-dimensional phase space can be trivially quantized. The constraints of the theory glue the quantum states over the individual edges so as to form a Hilbert space over the entire boundary of the underlying simplical manifold. The boundary states represent projected spin-network functions [59, 60] in the kinematical Hilbert space of loop quantum gravity.
It is clear what should be done next: For any fixed boundary data we should define a path integral over the field configurations along the edges in the bulk. At this point, many details remain open, and we have only finished this construction for the corresponding model in three-dimensions [58], yet we do know, that whatever the mathematical details of the resulting amplitudes will be, they will define a version of spinfoam gravity [61].

Finally, there is the motion of the volume-weighted time normals, which endow the entire simplicial complex with a flow of conserved energy-momentum. As shown by Cortês and Smolin in a related paper [27], these momentum-variables introduce a causal structure, and allow us to view the simplicial complex as an energetic causal set [51, 52]—a generalization of causal sets carrying a local flow of energy-momentum between causally related events.

==endquote==

 

[RUTA]

If you're going to stick p and E on the links of a simplicial manifold, you can use that structure as a base to specify Regge-calculus-like least action equations to marry up p and E with a spacetime metric. But, still, without a spacetime metric, p and E don't make sense. Putting them on the links of a graph doesn't change that.