The boundary proposal
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 eucl...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
September 2024
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| In: |
Physics letters
Year: 2024, Volume: 856, Pages: 1-7 |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2024.138946 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1016/j.physletb.2024.138946 Verlag, kostenfrei, Volltext: https://www.sciencedirect.com/science/article/pii/S0370269324005045 
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| Author Notes: | Bjoern Friedrich, Arthur Hebecker |
| Summary: | 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 Proposal, one may then be able to create a compact, flat torus universe from nothing, without any exponential suppression or enhancement factors. |
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| Item Description: | Online verfügbar: 8. August 2024, Artikelversion: 9. August 2024 Gesehen am 20.03.2025 |
| Physical Description: | Online Resource |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2024.138946 |