Theory that space is itself a kind of container, so that objects have a position or motion or acceleration in relation to space itself rather than purely in relation to each other. In his famous ‘bucket’ thought experiment Newton noted that water spinning in a stationary bucket would creep up the sides, while the water stays flat if it is stationary, and the bucket is spinning. Newton concluded that to explain this asymmetry we must assume not just relative motion between objects but absolute motion with respect to space. The strongest such notion involves the idea of space as an existing thing with points which persist through time. Absolute motion is then change of place with respect to these points. However, to explain inertial effects such as the bucket experiment, one needs only a weaker notion of absolute space, relative to which there is absolute acceleration, but for which different inertial motions are all relative.