Fairly simple question I s'pose. If I've a perfect disc and I spin it about its centre, does the zero-dimensional point at its very centre actually rotate? On the one hand, if I imagine being at the centre and looking out in one direction, if the disc rotates 180°, I would've thought that I should be facing in the opposite direction. On the other hand, although obviously everything either side of it rotates, the central point itself has no sides, which suggests that if one were to rotate it 180° it wouldn't have changed at all, because a point would not seem (to me at least) to be facing in any particular direction. If it did rotate 180°, then this would imply its 'north face' would now be facing south and vice-versa. Same question for a one-dimensional line going through the centre of the disc.