A space, or spaces, that are left in structures, roads, or streets which allow for the expansions and contractions of the materials which are caused by heat and cool environments.

A feature of our universe deduced from the observation that the distant galaxies' light is red-shifted.

Observations so far have not succeeded in determining whether the universe is open (of infinite extent in space) or closed (of finite extent) and whether the universe in the future will continue to expand indefinitely or will eventually collapse back into an extremely dense, congested state.