1. Forgive me for this novice question, but can variation in the expansion rate of the universe, be partially explained by an increasing number of stars turning mass into energy, hence reducing gravitational attraction between galaxies, and at the same time applying radiation pressure (a small pushing effect) to matter outside of galaxies? Or are these effects, if any, negligible? 2. Another related question about the voids between galaxies clusters: Are they observed to be expanding in size at a rate which confirms that the cosmological constant is truly constant everywhere, including within the threads of galaxies, after taking into account gravitational attraction? 3. Another related question about dark matter: Since dark matter is estimated at 5.5x the mass of the ordinary matter in the Universe, is this sum of all of this gravitational attraction still consistent with the expansion rate of the Universe? I believe that dark matter is thought to accumulate near the rim of spiral galaxies, but I am not sure about this. If so, is this situation also accounted for in question 2? http://en.wikipedia.org/wiki/File:080998_Universe_Content_240_after_Planck.jpg 4. I just saw this chart above for the first time, why is the percentage of dark matter and ordinary matter changing?! Is this solely the result of fusion in stars? Do we consider the matter inside Black Holes to be ordinary matter? Quite a lot covered there, thanks for any replies.