Friday, November 17, 2006

The dark side of the Force.

A couple of years ago, NASA was ready to give up on the Hubble Space Telescope, apparently content to allow it to go dark. Now, there are plans to repair it so it can keep doing what it does so well. Its value has just been made more evident by the images it has captured of supernovae in galaxies so distant that their light has taken half the estimated age of the universe to reach earth. As related in this article, the red-shifting of the light from these supernovae shows that the expansion of the universe has been accelerating over time. This can be explained by positing the existence of a contra-gravitational force called "dark energy". Einstein, in his theoretical work, once concluded that there is such a force, but later called this his "greatest blunder". It appears now that he was right the first time.

Here is a Hubble image of a supernova remnant, the Crab Nebula, in our own galaxy.