  The Standard Model of cosmology of the 1980's was based on a remarkable
interplay of ideas from particle theory, experiment and astrophysical
observations. That model is now dead, and has been replaced by something far
more bizarre. Interestingly, the aspect that has survived involves perhaps the
most exotic component: dark matter that dominates the gravitational dynamics of
all galaxies, and appears to be composed of a sea of new weakly interacting
elementary particles. But this sea of dark matter appears to play second fiddle
to an unknown energy density that appears to permeate all of space, causing the
expansion of the Universe to accelerate. We are left with many more questions
than answers, and our vision of the future of the Universe has completely
changed. (Lectures Given at the XIV Canary Islands Winter School in
Astrophysics 2002: Dark Matter and Dark Energy in the Universe. Nov 2002 To
Appear in the Proceedings)
