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by MattPalmer1086
606 days ago
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The vacuum has nothing to do with causality. It's just that light (if there is nothing in its way, so in a vacuum) will travel at the max speed of causality. Causality violation can happen in general relativity when something moves faster than the max speed of causality (which is the same speed as light in a vacuum). |
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The only theoretical case I’m aware of are closed timelike curves (CTC) which are paths in spacetime that loop back on themselves, allowing an object to return to its own past. A famous example is the Gödel metric, a solution to Einstein’a field equations.
It should be noted, however, that these solutions are generally regarded as unphysical because they require conditions that don’t seem to exist in our universe (such as a globally rotating universe).