- #1

Jarek 31

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- 31

- TL;DR Summary
- (Why) Can we be certain that spacetime is orientable?

Einstein's general relativity theory assumes that spacetime is a manifold with intrinsic curvature proportional to stress-energy tensor.

But manifolds, in principle, can be non-orientable, like Möbius strip or Klein bottle:

So could spacetime be non-orientable?

If not, is that because of impossibility of getting such stress-energy tensor configuration, or are there some other reasons?

If yes, could e.g. traveling through such Klein-bottle-like wormhole perform P or T symmetry on such object?

I have found 3 peer-reviewed articles optimistic about such possibility (should they be so?):

Nonorientable spacetime tunneling: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.59.064026

Observing other universes through ringholes and Klein-bottle holes: https://aip.scitation.org/doi/abs/10.1063/1.4734422?download=true&journalCode=apc

The orientability of spacetime: https://iopscience.iop.org/article/10.1088/0264-9381/19/17/308

But manifolds, in principle, can be non-orientable, like Möbius strip or Klein bottle:

So could spacetime be non-orientable?

If not, is that because of impossibility of getting such stress-energy tensor configuration, or are there some other reasons?

If yes, could e.g. traveling through such Klein-bottle-like wormhole perform P or T symmetry on such object?

I have found 3 peer-reviewed articles optimistic about such possibility (should they be so?):

Nonorientable spacetime tunneling: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.59.064026

Observing other universes through ringholes and Klein-bottle holes: https://aip.scitation.org/doi/abs/10.1063/1.4734422?download=true&journalCode=apc

The orientability of spacetime: https://iopscience.iop.org/article/10.1088/0264-9381/19/17/308