Algebras of Quantum Variables for Loop Quantum Gravity, I. Overview

Abstract: The operator algebraic framework plays an important role in mathematical physics. Many different operator algebras exist for example for a theory of quantum mechanics. In Loop Quantum Gravity only two algebras have been introduced until now. In the project about 'Algebras of Quantum Variables (AQV) for LQG' the known holonomy-flux -algebra and the Weyl C-algebra will be modified and a set of new algebras will be proposed and studied. The idea of the construction of these algebras is to establish a finite set of operators, which generates (in the sense of Woronowicz, Schm\"udgen and Inoue) the different O*- or C*-algebras of quantum gravity and to use inductive limits of these algebras. In the Loop Quantum Gravity approach usually the basic classical variables are connections and fluxes. Studying the three constraints appearing in the canonical quantisation of classical general relativity in the ADM-formalism some other variables like curvature appear. Consequently the main difficulty of a quantisation of gravity is to find a suitable replacement of the set of elementary classical variables and constraints. The algebra of quantum gravity is supposed to be generated by a set of the operators associated to holonomies, fluxes and in some cases even the curvature. There are two reasonable choices for this algebra: The set of constraints of Quantum Gravity are contained in or at least the constraints are affilliated with this algebra. Secondly, the algebra of quantum variables is said to be physical if it contains complete observables. In the project of 'Algebras of Quantum Variables for LQG' different algebras will be studied with respect to the property of being a physical algebra. Furthermore the existence of KMS-states on these algebras will be argued.