I am a cosmologist in the Department of Astronomy at Harvard University.  I have worked on a wide variety of topics in astrophysics but am best known for my use of the baryon acoustic oscillation phenomenon to measure the cosmological distance scale and thereby the evolution of dark energy.
I was born in 1970 in Israel to Drs Robert and Karolyn Eisenstein. My parents returned to the United States when I was a month old, taking up academic jobs in Pittsburgh, Pennsylvania, and later in Champaign, Illinois.  My younger brother Bill and I have always been close; he is now an environmental planner at UC Berkeley. My interest in science and math started early, fed by my parents’ scientific careers and by numerous encouraging teachers.
I was an undergraduate at Princeton University, majoring in physics and getting my first exposure to cosmology and astrophysics. College was very rewarding, not only for the excitement of pursuing advanced physics and mathematics but also for my personal development through campus activities and independent study. My senior thesis was advised by Professor David Spergel, who received the Shaw Prize in 2010. I graduated Princeton in 1992 as valedictorian.
I went to Harvard University for graduate work in physics. My 1996 PhD thesis with Professor Abraham Loeb focused on applications of the theory of cosmological structure formation to the origin of quasars and the Tully–Fisher relation of spiral galaxies.
I was a post-doctoral researcher at the Institute for Advanced Study in Princeton, New Jersey, and then a NASA Hubble Fellow at the University of Chicago. It was at this time that I started my work on the effects of baryon acoustic oscillations on the large-scale distribution of galaxies. Through my interest in the statistical methods in cosmology, I became active in the Sloan Digital Sky Survey, helping to implement the galaxy target selection and becoming the lead for the luminous red galaxy sample.  This was my introduction to observational astronomy data and to large-scale collaborative astronomy.
I moved to a junior faculty position at the University of Arizona in 2001. My group and I continued development of the baryon acoustic oscillation method, forecasting the opportunity for the study of dark energy and refining the theory through both analytic work and cosmological N-body simulations. At the same time, I was leading the analysis of clustering of luminous red galaxies from the Sloan Digital Sky Survey. Our announcement in 2005 yielded the then-strongest detection of the baryon acoustic oscillations. We produced a 4% measurement of the distance to redshift 0.35 and provided a clear connection between the cosmic structure observed today and that seen in the cosmic microwave background from 400,000 years after the Big Bang.
I became Director of the Sloan Digital Sky Survey III in 2006. SDSS-III commenced operations in 2008 and includes over 800 scientists from    fifty-one member institutions. The largest component of SDSS-III is the Baryon Oscillation Spectroscopic Survey (BOSS), which is currently the largest galaxy redshift survey in existence. With BOSS, the baryon acoustic oscillations method has fully come of age, providing a 1% distance measurement to the galaxy sample as well as robust detections of the same effect in the clustering of the intergalactic medium at redshift 2.4.  SDSS-III completed its observations in June 2014 and we are looking forward to the final data release at the end of the year.
I moved to Harvard University in 2010, where I continue development of facilities for the next generation of wide-field surveys featuring the utilization of the baryon acoustic oscillations as their key application.  Building on my work for early instrument concepts for the Gemini telescope and the NASA/DOE Joint Dark Energy Mission, I am now co-Spokesperson for the DOE-led Dark Energy Spectroscopic Instrument (DESI) and a member of SDSS-IV and the Euclid Collaboration. With these exciting new projects, cosmologists will map the Universe out to redshift 3 and use the baryon acoustic oscillation method to achieve precision on the distance scale below 0.3%.
My wife, Dr Annalisa Prahl, is a veterinarian, specializing in internal medicine. We met in Tucson, Arizona, in 2004 and were married in 2006.  Following the cosmological concept that every observer perceives their own centre of the Universe, ours is centred around our two young sons, Alexander and Julian.

24 September 2014   Hong Kong