The abstract says "the noncommutativity of translations permits translation without momentum exchange in either gravitationally curved spacetime or the curved s

The abstract says "the noncommutativity of translations permits translation without momentum exchange in either gravitationally curved spacetime or the curved surfaces encountered by locomotors in real-world environments." The idea isn't new. This is an experimental verification of it in the case of curved surfaces, not gravitationally curved space, but it should work for both.