2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/175402Spacetime manifolds that are not time orientable play a key role in a gravitational explanation of quantum theory. Such manifolds allow topology change, but also have fascinating additional properties such as net charge from source-free equations and spin half transformation properties. It is shown how the logical structure of propositions and the probabilities of quantum theory arise from such acausal space times7 pages Talk given at FFP8 in Madrid 2006General Relativity and Quantum Cosmologytext