Carnegie Mellon University
April 19, 2012

Press Release: Director of the Sloan Digital Sky Survey III To Deliver Carnegie Mellon's 2012 Buhl Lecture April 24

Harvard Astronomy Professor Daniel Eisenstein Will Discuss Universe's Expansion

Contact: Jocelyn Duffy / 412-268-9982 /

Daniel EisensteinPITTSBURGH—Daniel Eisenstein, director of the third phase of the Sloan Digital Sky Survey, will present Carnegie Mellon University's annual Buhl Lecture at 4:30 p.m., Tuesday, April 24 in the Mellon Institute Auditorium, 4400 Fifth Ave., Oakland. His lecture "Dark Energy and Cosmic Sound" is free and open to the public.

The acceleration of the expansion rate of the universe is one of the most vexing questions in modern physics. In his lecture, Eisenstein, an astronomy professor at Harvard University, will discuss how artifacts from the sound waves created during the first million years of the universe's existence can provide a critical observational test of the phenomenon.

After the Big Bang, the universe was a dense cloud of cosmic plasma. As the universe matured and cooled, matter began to clump together creating areas of high and low density, which would later become clusters of galaxies separated by giant voids. To this day, this structure bears the imprint of sound waves that traveled the early universe called baryon acoustic oscillations. Scientists can measure relics from the sound waves to precisely measure the location and distance of galaxies in the universe. From this information, they can measure dark energy.

The Sloan Digital Sky Survey is using data from the study of baryon acoustic oscillations, as well as other methods, to make the largest three-dimensional color map of the universe to date. Carnegie Mellon joined the survey last year, and a number of researchers from the Bruce and Astrid McWilliams Center for Cosmology are contributing to the project.

Eisenstein received his Ph.D. from Harvard and then held postdoctoral positions at the Institute for Advanced Study and the University of Chicago. He was a member of the faculty at the University of Arizona before moving to Harvard in 2010.

The Buhl Lecture is sponsored by Carnegie Mellon's Department of Physics. The lecture is funded under the auspices of the Buhl Professorship in Theoretical Physics, which was established at Carnegie Mellon in 1961 by The Buhl Foundation.


Harvard Astronomy Professor Daniel Eisenstein, pictured above, will give Carnegie Mellon's 2012 Buhl Lecture.