nLab no boundary proposal

Contents

Context

Cosmology

Quantum systems

quantum logic


quantum physics


quantum probability theoryobservables and states


quantum information


quantum computation

qbit

quantum algorithms:


quantum sensing


quantum communication

Contents

Idea

The Hartle-Hawking no-boundary-proposal in quantum cosmology [Hawking 1982, Hartle & Hawking 1983] is the informal assertion that wavefunctions Ψ(X 3,g)\Psi(X^3, g) on the space of spatial cosmological geometries (X 3,g)(X^3,g) are given by the path integral over all (partially Wick-rotated) 4d geometries whose only boundary is X 3X^3, hence which have no boundary in the past.

The idea is that this describes quantum states of the universe for those cosmological evolutions where the universe appears “out of nothing”.

References

The original articles:

  • S. W. Hawking, The Boundary Conditions of the Universe, Pontif. Acad. Sci. Scr. Varia 48 (1982) 563–574

  • J. B. Hartle, S. W. Hawking, Wave function of the Universe, Phys. Rev. D 28 2960 (1983) [doi:10.1103/PhysRevD.28.2960]

  • S. W. Hawking, section 3 of: The Nature of Space and Time [arXiv:hep-th/9409195]

Review and further discussion:

Last revised on March 18, 2024 at 07:41:39. See the history of this page for a list of all contributions to it.