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Within general relativity at least, I think this is impossible. The metric tensor of a pseudo-Riemannian manifold is usually taken to be everywhere nondegenerate (see e.g. this source. A metric is ...
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Within general relativity at least, I think this is impossible. The metric tensor of a pseudo-Riemannian manifold is usually taken to be everywhere nondegenerate (see e.g. this source. A metric is ...