The Boundary Proposal ...

• Main Authors: Friedrich, Bjoern, Hebecker, Arthur
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2024
• Subjects: High Energy Physics - Theory hep-th; General Relativity and Quantum Cosmology gr-qc; FOS Physical sciences; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2403.18892; https://arxiv.org/abs/2403.18892

One of the leading ideas for the beginning of the Universe is the Hartle-Hawking `No-Boundary Proposal.' Since the Cobordism Conjecture claims that any spacetime allows for a dynamical boundary, we suggest that one may equally well consider a `Boundary Proposal'. Specifically, the corresponding euclidean instanton is a sphere with two holes around north and south pole cut out. Analogously to the Hartle-Hawking proposal, the sphere is then cut in two at the equator and half of it is dropped. The equator is glued to an expanding Lorentzian de Sitter space, implementing a beginning of the Universe with a spacelike spherical boundary at its earliest moment. This process is in principle on equal footing with the one based on the no-boundary instanton. In fact, if the Linde-Vilenkin sign choice is used, this `Boundary' creation process may even dominate. An intriguing implication arises if tensionless end-of-the-world branes, as familiar from type-IIA or M-theory, are available: Analogously to the Boundary ... : 14 pages, 3 figures ...