by Surabhi Agarwal

What is the Universe made of? Observations suggest surprising results: not only most of the matter in the Universe is dark and unconventional but, more surprisingly, the major component of the Universe may be in the form of ‘dark energy’ — a form of energy that opposes the pull of gravity and causes the expansion of the universe to accelerate. By combining observations of large-scale structure, distant supernovae, and the cosmic microwave background, we find evidence for a Universe that has only 5% ‘normal’ baryonic matter, 20% non-baryonic dark matter, and 75% ‘dark energy’. The observations suggest a Universe that is lightweight, with only 25% of the critical mass-density needed to halt the Universal expansion, and a geometry that is flat with no space curvature.

Neta A. Bahcall, the Eugene Higgins Professor of Astrophysics and the Director of the Undergraduate Program in Astrophysics at Princeton University will discuss her observations on the Dark Side of the Universe and their implications on Tuesday May 13^th 2014. Bahcall is a member of the National Academy of Sciences, Distinguished Research Chair at the Perimeter Institute for Theoretical Physics, past Vice-President and Councilor of the American Astronomical Society, Century Lecturer of the AAS, and Chair and member of various NASA, NSF, and Congressional committees.

Bahcall has won numerous awards during her distinguished career. Some of the most recent ones are:
•The Cecilia Payne-Gasposkin Prize, Harvard University (2013)
•Distinguished Research Chair, Perimeter Institute for Theoretical Physics, Ontario, Canada (2009 -2013 )
•Frontiers of Astronomy Lecturer, CWRU (2009)
•Evnin Lecturer, Princeton University (2008)
•Honorary Degree, Doctor of Science, The Ohio State University (2006)

She has penned hundreds of research papers. Some of her latest ones are:
•“SDSSIII Photometric Quasar Clustering: Probing the Initial Conditions of the Universe Using the Largest Volume” (S. Ho et al), JCAP (2013)
•“On the Determination of Cluster Masses: Lensing versus SZ/Xray Mass” (N. Bahcall and Allison Hume), in preparation (2013)
•“Supermassive Black Holes in Quasars” (N. Bahcall, M. DiDonato, M. Medeiros), in preparation (2013)
•“Tracing Dark Matter and Baryons in the Universe”, (N. Bahcall and B. Cook), in preparation (2013)
•“Baryon Acoustic Oscillations Using Clusters of Galaxies” (N.Bahcall, H.Yesuf, P.Bode), in preparation (2013)

See you on Tuesday, May 13^th at 8:00 p.m. in Peyton Hall, 4 Ivy Lane, Princeton. The lecture will be followed by a business meeting.