AS102 Study Guide - Midterm Guide: Classical Planet
Document Summary
So, since this discovery in 1998, astronomers have set out to find out which possibility is valid and have generally referred to the force involved in the accelerating expansion as dark energy. It seems that when astronomers don"t know anything about some facet of our universe they use dark as the modifier. First there was dark matter and remember that we still don"t know what dark matter is but we know it exists. Now we have dark energy and we really still have no idea what it is; although it must be some mysterious repulsive force working against gravity. Here is a neat video from esa (european space agency) summarizing some of the more important features of the discovery of the accelerating expansion of the universe. http://www. youtube. com/watch?v=d_2ozqc-lzw. One thing that has been determined is that dark energy appears to have become important about 6 billion years ago when the universe was just over 50% of its current age.
