The new SDSS results (black dots) are the most accurate measurements to date of how the density of the Universe fluctuates from place to place on scales of millions of lightyears. These and other cosmological measurements agree with the theoretical prediction (blue curve) for a Universe composed of 5% atoms, 25% dark matter and 70% dark energy. The larger the scales we average over, the more uniform the Universe appears. Click image for a larger view.

The large-scale distribution of galaxies has long been recognized as a potent probe of the physics of the early universe. In particular, the power spectrum of galaxies is a direct reflection of the physics of inflation, which took place in the first 10^{-30} seconds following the Big Bang, and the physics of the growth of structure in the universe, which depends on the universe's growth rate and its contents, including dark matter. This paper is a definitive measurement of the galaxy power spectrum from what is now the largest and most precisely calibrated survey to date of galaxies.

Another recent paper, "Cosmological parameters from SDSS and WMAP," (Phys. Rev. D. 69 [10]: MAY 2004), uses this power spectrum, and combines it with results from other cosmological probes, especially the Cosmic Microwave Background, to constrain all this physics: the amount and nature of dark matter, the amount of dark energy, the physics in inflation, and so on. These are basic results of broad interest to all of extragalactic astronomy and cosmology, which is why these papers have been so broadly cited.

It is worth mentioning that our results confirm and extend results that had already been published by other galaxy surveys, in particularly the so-called 2dF survey. The resulting papers there have also been very widely cited.

The detailed methodology used in our papers differs in some aspects from what has been done before—indeed, we think we've done a more careful job than previous researchers. In some sense, however, we haven't really made a new discovery: one of the most dramatic results of our papers is the extent to which we confirm and are in concordance with conventional wisdom about the nature of cosmology.

The project here is one of the key science drivers of the SDDS. We have been involved in this work for many years, and carrying out this analysis was always one of the big projects we had planned to do.

One of the things which I should emphasize is that the attention this work is receiving is really the result of the entire SDDS collaboration.

The SDSS is a joint project of The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Korean Scientist Group, Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.