The expansion of the universe might have a different cause than the proposed 'dark energy', antimatter gravity which should repel: > > > http://www.physorg.com/news/2011-04-antimatter-gravity-universe-expansion.html-A completed four-year study demonstrates that 'dark energy' is real and fits Einstein's predictions:-http://www.physorg.com/news/2011-05-wigglez-galaxy-einstein.html