>>120476691. because the only phenomenon we know of that exhibits negative spacetime curvature is dark energy and we have no idea how that shit works. A lot of physicists think that DE isn't even a thing, but an indicator that GR is an incomplete theory of gravity and doesn't accurately work on cosmological scales.
2. Any form of faster-than-light travel is absolute fiction as it breaks causality.
>>12047708Casimir effect is a tiny ass effect relevant on quantum scale. We have no fucking clue how it manifests itself at GR scales since it requires a working theory of quantum gravity, which we don't currently have.
