Initial wave-function of the universe is arbitrary

Abstract

We consider quantization of the gravity-scalar field system in the minisuperspace approximation. It turns out that in the gauge fixed deparametrized theory where the scale factor plays the role of time, the Hamiltonian can be uniquely defined without any ordering ambiguity as the square root of a self-adjoint operator. Moreover, the Hamiltonian degenerates to zero and the Schrödinger equation becomes well behaved as the scale factor vanishes. Therefore, there is no technical or physical obstruction for the initial wave-function of the universe to be an arbitrary vector in the Hilbert space, which demonstrates the severeness of the initial condition problem in quantum cosmology.

6 pages, v3: comments added, the results are generalized to the most general spatially flat minisuperspace model

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Cited by in corpus (3)

• Schrödinger from Wheeler-DeWitt: The Issues of Time and Inner Product in Canonical Quantum Gravity
• Big-Bang is a Boundary Condition
• A (semi)-exact Hamiltonian for the curvature perturbation $\zeta$