In its original form the density parameter Omega represented the ratio of the actual density of the universe to the critical density; i.e. the density required to halt the universe’s expansion and that would then cause it to contract. If Omega is greater than one the universe is said to be finite and closed with positive curvature. If Omega is less than one the universe is said to be infinite and open with negative curvature. If Omega is equal to one the universe is said to be open and infinite with zero curvature. According to the Big Bang Theory, the universe contains all the volume that exists and it is not expanding into previously unoccupied space. Regardless of whether the overall geometry is flat, negative or positive the universe has no edge and does not need additional room to expand. This seems to imply that the existing space is being stretched out as the universe expands. However, if space is a something – a substance of sorts - that is influenced by the presence of mass, it would seem that space itself may in a sense possess a certain amount of mass. But if space does possess a certain amount of mass, what happens as this space is thinned out over time? As galaxies are gravitationally stable this does not seem to pose a problem but on an intergalactic scale it would seem that gravitationally the influence of a massive structure such as a galaxy on other galaxies would be changing over time. I am not sure if this was what Einstein was thinking when he made his self-described “greatest blunder” by proposing a cosmological term that acted in opposition to gravity and produced a static universe. As this cosmological term – the cosmological constant - is now a prime candidate for the source of the accelerating expansion of the universe, Einstein may have been right from the beginning. However, the questions I have are: If space is indeed a substance of some sort that can expand and contract, as space expands (intergalactically) would these changes in density affect the predictions of the theory of general relativity? Or is it possible that rather than expanding, new space is somehow constantly being created to maintain a constant density?