Dr. Neta A. Bahcall

By Ira Polans, Program Chair

 The March meeting of the AAAP will be held on the 9th at 7:30 PM in Peyton Hall on the Princeton University campus. The speaker is Dr. Neta A. Bahcall, Eugene Higgins Professor of Astrophysics at Princeton University. Dr. Bahcall will discuss “The Dark Side of the Universe”.

What is the Universe made of? Recent observations suggest surprising results: most of the content of the Universe is dark and unexpected; 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 recent observations of clusters 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; the Universe will likely expand forever. Dr. Bahcall will discuss the observations of the dark side of the Universe and their implications.

We will not have a March meet-the-speaker dinner.

Our April speaker will be Dr. James Green, Director of the Planetary Science Division at NASA Headquarters. Dr. Green will speak on “New Discoveries in the Outer Solar System: Ceres, Pluto, and Planet X”.

We urge you and friends to attend one or both of these meetings.