Your assumption appears to be that the expanding universe model is about objects in the universe moving away from one another through empty space at fixed initial velocities, an essentially Newtonian view of the expanding universe.

However, we do not live in a Newtonian universe. We live in a Einstinian relatavistic universe and in that universe space time is not just empty nothing through which matter moves. It is the fabric of the universe. Matter bends space time to create gravity. And space time in turn effects matter. In the expanding universe model, the recession of the galaxies is the result not of inertial (Newtonia) motion of the galaxies themselvs but rather is a consequence of the expansion of space time itself. In this model, recession rate correlates to distance and does change over time (since distance changes over time).

As an example, consider a hypothetical universe of 3 stars, A, B, and C. Let's assume that at a point in time the distance between A and B is 1 ly. The distance between A and C is 100 ly. If our hypothetical universe is expanding at 1% per year, then over the course of a year, B moves .01 ly away from A. C moves 1 ly (it is receeding from A at the speed of light although, in a strictly Newtonian sense, it isn't moving at all). Now consider these same three stars at an earlier time when they were half as far apart. Assuming the same expansion rate, B would be receding from A at .005 ly/y. C would be receding from A at .5 ly/y. Light in such a model requires more than 1 year to cross a light year because it is moving through space time and space time is itself expanding.

Of couse I'm not a cosmologist so the above explanation is purely a layman's understanding of the concept. That being said, your graph doesn't reflect the dynamics of the expanding universe model as I understand it. So either my understanding of the concept is wrong or yours is.


<font size=-1>[ This Message was edited by: Espritch on 2002-06-10 22:23 ]</font>