Hi Cable
Yes there is evidence of this loss of energy. As space-time expands, it requires energy to do so. This energy is extracted from our universe. This is what is usually associated with “dark energy”. Recent articles on the distribution of galaxies have proposed a rather significant amount of dark energy. Sloan Digital Sky Survey News Release
http://www.sdss.org/news/releases/20...rspectrum.html There is no theoretical explanation for the distribution for this dark energy and dark mater. It is just observed.
If you have time, check out the theory section of my paper and you will see a balloon that is expanded. Usually if you look at most college level explanations for the expansion of the universe, you will see something, putting air into the balloon to blow it up, which is supposed to represent the expansion of the universe. This would cause an increase in the amount of energy in the balloon- universe. If instead the tension of the balloon decreased, the balloon would still expand but the energy contained in the balloon would be diminished. This is somewhat like the loss of energy our universe experiences as the universe expands except instead of a two dimensional surface, it is more like a three dimensional surface.
yours,
snowflake.