TY - JOUR
T1 - Some surprising implications of background independence in canonical quantum gravity
AU - Ashtekar, Abhay
N1 - Funding Information:
Acknowledgments The need for clarification of the unusually strong role of diffeomorphism invariance was brought to forefront during discussions in the 2007 KITP workshop on Classical Singularities in Quantum Space-times. I would like to thank Ted Jacobson and Don Marolf for raising interesting questions and Jerzy Lewandowski for discussions. This work was supported in part by the NSF grants PHY0456913 and PHY0854743, The George A. and Margaret M. Downsbrough Endowment and the Eberly research funds of Penn State.
PY - 2009/8
Y1 - 2009/8
N2 - There is a precise sense in which the requirement of background independence suffices to uniquely select the kinematics of loop quantum gravity (LQG). Specifically, the fundamental kinematic algebra of LQG admits a unique diffeomorphism invariant state. Although this result has been established rigorously, it comes as a surprise to researchers working with other approaches to quantum gravity. The goal of this article is to explain the underlying reasons in a pedagogical fashion using geometrodynamics, keeping the technicalities at their minimum. This discussion will bring out the surprisingly powerful role played by diffeomorphism invariance (and covariance) in non-perturbative, canonical quantum gravity.
AB - There is a precise sense in which the requirement of background independence suffices to uniquely select the kinematics of loop quantum gravity (LQG). Specifically, the fundamental kinematic algebra of LQG admits a unique diffeomorphism invariant state. Although this result has been established rigorously, it comes as a surprise to researchers working with other approaches to quantum gravity. The goal of this article is to explain the underlying reasons in a pedagogical fashion using geometrodynamics, keeping the technicalities at their minimum. This discussion will bring out the surprisingly powerful role played by diffeomorphism invariance (and covariance) in non-perturbative, canonical quantum gravity.
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U2 - 10.1007/s10714-009-0802-1
DO - 10.1007/s10714-009-0802-1
M3 - Article
AN - SCOPUS:78650965716
SN - 0001-7701
VL - 41
SP - 1927
EP - 1943
JO - General Relativity and Gravitation
JF - General Relativity and Gravitation
IS - 9
ER -