Natural SciencesPhysicsGravitationQuantum MechanicsTheoretical PhysicsGeneral RelativityPhilosophy Of PhysicsQuantum Field TheoryQuantum GravityQuantum PhysicsSpacetime GeometryCanonical QuantizationCanonical Quantum GravityQuantizationTime-dependent Quantum MechanicsVector Quantization
In canonical quantization of gravity, the state functional does not seem to depend on time. This hampers the physical interpretation of quantum gravity. I critically examine ten major attempts to circumvent this problem and discuss their shortcomings.