#### marcus

Science Advisor

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In case there is need for discussion, it should probably have its own thread as well.

The paper expands a key assertion made on page 173 of the on-line draft of Rovelli's book "Quantum Gravity".

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"Separable Hilbert space in loop quantum gravity"

http://arxiv.org/abs/gr-qc/0403047

By Carlo Rovelli and Winston Fairbairn

Abstract:"We study the separability of the state space of loop quantum gravity. In the standard construction, the kinematical Hilbert space of the diffeomorphism-invariant states is nonseparable. This is a consequence of the fact that the knot-space of the equivalence classes of graphs under diffeomorphisms is noncountable. However, the continuous moduli labeling these classes do not appear to affect the physics of the theory. We investigate the possibility that these moduli could be only the consequence of a poor choice in the fine-tuning of the mathematical setting. We show that by simply choosing a minor extension of the functional class of the classical fields and coordinates, the moduli disappear, the knot classes become countable, and the kinematical Hilbert space of loop quantum gravity becomes separable"

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