<P> Humans, like all known things in the universe, are in constant motion, however, aside from obvious movements of the various external body parts and locomotion, humans are in motion in a variety of ways which are more difficult to perceive . Many of these "imperceptible motions" are only perceivable with the help of special tools and careful observation . The larger scales of "imperceptible motions" are difficult for humans to perceive for two reasons: 1) Newton's laws of motion (particularly Inertia) which prevent humans from feeling motions of a mass to which they are connected, and 2) the lack of an obvious frame of reference which would allow individuals to easily see that they are moving . The smaller scales of these motions are too small for humans to sense . </P> <Ul> <Li> Spacetime (the fabric of the universe) is actually expanding . Essentially, everything in the universe is stretching like a rubber band . This motion is the most obscure as it is not physical motion as such, but rather a change in the very nature of the universe . The primary source of verification of this expansion was provided by Edwin Hubble who demonstrated that all galaxies and distant astronomical objects were moving away from us ("Hubble's law") as predicted by a universal expansion . </Li> </Ul> <Li> Spacetime (the fabric of the universe) is actually expanding . Essentially, everything in the universe is stretching like a rubber band . This motion is the most obscure as it is not physical motion as such, but rather a change in the very nature of the universe . The primary source of verification of this expansion was provided by Edwin Hubble who demonstrated that all galaxies and distant astronomical objects were moving away from us ("Hubble's law") as predicted by a universal expansion . </Li> <Ul> <Li> The Milky Way Galaxy is moving through space . Many astronomers believe the Milky Way is moving at approximately 600 km / s relative to the observed locations of other nearby galaxies . Another reference frame is provided by the Cosmic microwave background . This frame of reference indicates that The Milky Way is moving at around 582 km / s . </Li> </Ul>

When do you say that their is motion