imagine an astronaut were all alone in a different universe. it just has an astronaut and a spaceship. is he moving? is he standing still? those questions do not mean anything. why? because when we say we are moving we mean that we can measure our distance from something else at various times. if the numbers get bigger we are moving away. if the numbers get smaller we are moving closer. to have movement you must have at least two things. an airplane can be moving at several hundred kilometers per hour, but passengers say, "i am just sitting here."