Even in a model where it really matters when one arrives at each point in space (e.g. if we were merely collecting the flow of starlight, and where the stars burning out set the relevant end point for useful expansion) I believe the relevant number is still very small: 4/R where R is the relevant radius of expansion in light years. The 4 is because this grows as a quartic. For my model, it is 3/R, where R is 16.7 billion light years.
Even in a model where it really matters when one arrives at each point in space (e.g. if we were merely collecting the flow of starlight, and where the stars burning out set the relevant end point for useful expansion) I believe the relevant number is still very small: 4/R where R is the relevant radius of expansion in light years. The 4 is because this grows as a quartic. For my model, it is 3/R, where R is 16.7 billion light years.