How well understood is motion, really? Physics is supposed to be the science that predicts and explains all motions of matter; it describes the laws that govern the forces that move things. But there are some big gaps. The motions of particles are notoriously unpredictable and inexplicable at the quantum level, but at the cosmic level we have the problem of explaining galaxy acceleration–the universe is expanding more slowly than the calculated amount of matter in it would make us expect, given the accepted rules of gravity. Physicists have taken to speaking of “dark matter” a what accounts for the extra pull, but there is absolutely no evidence for the existence of such a thing–and isn’t the idea of intrinsically invisible matter an oxymoron? It’s just sheer handwaving. So we don’t know why the cosmos is movingas it is. Do we know why animal bodies move as they do? Doesn’t the mind play a role in “determining” these movements? But physics has nothing to say about the forces that govern the mind and its capacity to induce motion. I sometimes wonder if any motion has really been explained.