I will present galaxy clustering results from the Sloan Digital Sky Survey that reveal the fossil imprint of sound waves that propagated through the cosmic gas in the first million years of the Universe. The scale of this feature can be computed and hence the detection in the galaxy clustering serves as a cosmic yardstick, giving a geometric distance to the galaxies in the survey. I will discuss the implications of this measurement for the composition of the universe, including dark energy and spatial curvature, and the prospects for future redshift surveys to use the acoustic signature to map the expansion history of the universe. This talk is intended for a general audience.

There will be a reception and book signing after the lecture for Mr. Graun, who has recently published the book: "The Next Step: Finding and Viewing Messier's Objects."

Since 1924, Steward Observatory has been hosting public evening lectures in astronomy. The four lectures for the Spring 2005 semester will be held on Monday nights at 7:30pm in Room N210 of Steward Observatory. Following all talks, there will be opportunities for viewing the night sky (weather permitting) with the use of the 21-inch telescope at the Campus Station of the Observatory operated by undergraduate majors in astronomy and related sciences. All of the lectures and the use of the telescope are free of charge and open to the general public.

As Hubble and other Great Observatories peer further back into the origins of our universe, it seems we find ourselves commensurately further away from a full understanding for the origin and evolution of galaxies. The largest galaxies that we can see to the furthest distances are particularly puzzling, showing abundances and colors that present challenges for current theories of galaxy formation. I will describe recent progress from cosmological hydrodynamic simulations towards unraveling some of these puzzles. While simulations suggest a physical mechanism for the "downsizing" of galaxies, i.e., the reduction in the characteristic mass of actively star forming objects, this mechanism cannot yet explain the strength of downsizing seen in the real universe. I will then go on to describe work towards understanding the progenitors of massive galaxies as observed at z~4 by the GOODS legacy project, and present preliminary comparisons and predictions that will help us constrain the early evolution of massive systems.

There has been tremendous interest and excitement surrounding the recent mission to Saturn's moon Titan. The DISR instrument, based at the University of Arizona, took all those strange but somehow familiar images as it fell towards the surface of Titan almost a billion miles away. Dr. Lisa McFarlane, DISR imaging team member, will give a presentation to share some of the excitement surrounding this mission, including images from the descent to Titan and a few photos and personal experiences from the encounter in Europe. The presentation will include a sense of what the DISR instrument was supposed to do and how well it performed. Work in progress will be touched upon and a few assembled collections of images, not yet released, will be shown.

“The Majestic Clockwork”, an episode from the excellent BBC series The Ascent of Man, written by and featuring philosopher Jacob Bronowski. The application of mathematics to the study of the motion of celestial objects, by Kepler, Newton, and eventually Einstein, brought about great advances in astronomy, physics, and mathematics. (Video, color, 1974: 52 minutes.)

The Fast Multipole Method (FMM) was named one of ten “algorithms with the greatest influence on the development and practice of science and engineering in the 20th century” in Computing in Science & Engineering (Jan/Feb 2000). Its inventors Rokhlin and Greengard won the 2001 AMS Steele prize. Is there anything left to say after more than 1000 papers devoted to fast numerical solutions of Poisson's equation? Comparitively less attention has been devoted to the FMM with periodic boundary conditions, a problem central to computational astronomy, chemistry, and biology. I will discuss some of the finer points of efficiently implementing the FMM, in particular a technique for extending the FMM to periodic boundary conditions.