Mention of the possibility to use ideas from condensed matter, where decoherence also plays an important role.

Issue is superposition of spin networks, as basis states of the Hilbert space of the theory. Decoherence can be applied to deal with [and suppress] this superposition.

Move on to application of decoherence in gravitational setting, i.e. in the context in which coupling with metric [gravitational field] is taken into account. From here, to the context in which the same field is quantized: loop quantum gravity

Decoherence also suggests an explanation of why special bases (e.g. positions or energy levels) are “preferred” in given physical situations, again in terms of the coupling with the environment (which includes the measurement apparatus).

Clarifications requested from audience. Speaker agrees: decoherence does not select a given quantum states, so it does not coincide with the measurement process. It only gives a physical mechanism for understanding the suppression of interference. In particular, it explains why we do not observe superpositions and interference of macroscopic objects. More discussion with the audience about this point.

Set aside, for present purposes, in particular for studying physical problems, the issue of interpretation. The focus here is on the specific physical process corresponding to measurement, and the way it suppresses superposition of quantum states.

General definition of decoherence, as due to entanglement between system and environment, leading to the appearance of classical or quasi-classical description of the same system. Not an interpretation of quantum mechanics, even though it plays an important role in several interpretations of quantum mechanics. It is a physical process.

Stressing the importance of decoherence in quantum mechanics in general, and of the interest in studying it in the context of quantum gravity.

The Role of Decoherence in Quantum Loop Dynamics

CW stresses that locality of spin network structures and captured by connectivity of these networks is very different from locality of relativistic STs.  Something very distinct is going on here…

CONCLUSION: classical space and time seem to disappear in canonical q grav, and they might re-emerge from fundamental non-ST structure.