Since Albert Einstein first proposed it, then withdrew his idea because it was just too weird to believe, physicists have puzzled about ‘dark matter.’
Two recent discoveries suggest that hard evidence of dark matter has been detected. The first of these startling discoveries is that the universe has recently started speeding up (by ?recently,? they mean between 4 and 8 billion years ago). And now the Hubble Space Telescope has spotted an ancient exploding star that provides evidence that a mysterious form of ?dark energy? is causing the expansion of the universe to accelerate.