Discovering Dark Energy and New Developments in our Understanding

Editor's Note: Bruce Macintosh, the original speaker scheduled to talk on "Pictures of Distant Worlds", has been called out of town.  This talk will be given instead.

Our Universe has provided many surprises to astronomers. One hundred years ago, Edwin Hubble showed it is expanding. In the 1990s, we found that the expansion is not slowing down as expected, but speeding up. This led to a Nobel Prize in Physics (for our speaker's students) and a consensus that we live in a universe that is made up of invisible dark matter, mysterious dark energy, and only a pinch of the atoms we, and everything we can see in the Universe, are made of. Recent observations indicate that even this picture may be too simple to account for all the evidence. Perhaps the dark energy is not the factor Einstein invented (and discarded) in his ideas about the universe, but something else that evolves with time. Nature is more inventive than human imagination!

Speaker: Robert Kirshner, California Institute of Technology