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marcus

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## Main Question or Discussion Point

If you've followed loop-gravity research since 2011 you know there've been big changes in the past couple of years--one being the emergence of the

He has an interesting new way to look at loop-gravity where the basic spin(or) network graph reflects a finite SAMPLING of geometry possibly associated with a particular observer and there are procedures on the one hand for COARSE-GRAINING (which eliminates some vertices and leaves self-loops at the remaining ones) and on the other hand for REFINING (the reverse, which adds vertices).

His approach allows for self-loop creation and annihilation operators and a self-loop FOCK SPACE representing an overlay of geometric distortion on the observer's basic spin(or) network.

The geometry Fock space holds information which comes into play when the network is refined.

This impresses me as definitely something to keep track of, so I'll quote from Livine's October 2013 paper "Deformation Operators of Spin Networks and Coarse-Graining"

==quote page 22 http://arxiv.org/abs/1310.3362 ==

Since self-loops are the gauge-fixed counterpart of the internal loops, we imagine a different structure for loop quantum gravity. Instead of defining a loop gravity dynamics that induces transitions between states living on different graphs, one could start with a fixed background graph (reflecting a certain sampling of space, possibly as probed and measured by a given observer) with dynamics acting on that fixed graph but possibly creating and annihilating self-loops at every vertex of that graph. We could then work on a Fock space over the background graph, with spin network states living on that background graph but also on any extension of it with extra self-loops. These self-loops account for the (possible) internal structure of each vertex and represent the coarse-graining of any more refined graph that could be obtained by the dynamics from the background graph.

==endquote==

**spinor**network formulation. Livine, Wieland, Speziale are some of those involved. I see Etera Livine is a visiting fellow at Perimeter as well as being on the faculty at ENS Lyon.He has an interesting new way to look at loop-gravity where the basic spin(or) network graph reflects a finite SAMPLING of geometry possibly associated with a particular observer and there are procedures on the one hand for COARSE-GRAINING (which eliminates some vertices and leaves self-loops at the remaining ones) and on the other hand for REFINING (the reverse, which adds vertices).

His approach allows for self-loop creation and annihilation operators and a self-loop FOCK SPACE representing an overlay of geometric distortion on the observer's basic spin(or) network.

The geometry Fock space holds information which comes into play when the network is refined.

This impresses me as definitely something to keep track of, so I'll quote from Livine's October 2013 paper "Deformation Operators of Spin Networks and Coarse-Graining"

==quote page 22 http://arxiv.org/abs/1310.3362 ==

Since self-loops are the gauge-fixed counterpart of the internal loops, we imagine a different structure for loop quantum gravity. Instead of defining a loop gravity dynamics that induces transitions between states living on different graphs, one could start with a fixed background graph (reflecting a certain sampling of space, possibly as probed and measured by a given observer) with dynamics acting on that fixed graph but possibly creating and annihilating self-loops at every vertex of that graph. We could then work on a Fock space over the background graph, with spin network states living on that background graph but also on any extension of it with extra self-loops. These self-loops account for the (possible) internal structure of each vertex and represent the coarse-graining of any more refined graph that could be obtained by the dynamics from the background graph.

==endquote==

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