Dark
Energy and Cosmic Sound
I
present
galaxy clustering results from the Sloan Digital Sky Survey that reveal
the
signature of acoustic oscillations of the photon-baryon fluid in the
first
million years of the Universe. The scale of this feature can be
computed and hence the detection in the galaxy clustering serves
as a
standard ruler, giving a geometric distance to a redshift of 0.35. I will discuss the implications of this
measurement for the composition of the universe, including dark energy
and
spatial curvature. I will close with a discussion of the
prospects for
future redshift surveys to use the acoustic peak to map the expansion
history
of the universe.