Asked by: Chris Hunt, Manchester
Our ‘position’ within the Universe is an entirely relative concept. We can easily define our position relative to the Sun and planets, and with respect to the nearest stars. We can also establish our approximate location within the spiral arms of the Milky Way, even though we are nestling within it. We have even determined the relative position of the Milky Way within its local group of galaxies and with respect to even more distant clusters of galaxies. But there is no universal reference frame to which we can ‘attach’ our position in the cosmos. The Big Bang happened everywhere at once and the Universe has been expanding ever since. So every point in the Universe can be regarded as being the ‘centre’ of the expansion. Since the Universe may not actually have a physical edge (only an observational one), there is no sense in the idea of an ‘absolute’ position.