Prestigious Alum returns to host astrophysics lecture
Dr. Sean Carroll Reflects on the Expanding Universe: Nostrums and Enigmas
Jason Fenner ‘03

Dr. Sean Carroll, a 1988 Villanova graduate with a degree in astronomy and minors in both physics and philosophy, returned to Villanova on Sept. 25 to discuss the wonders of the expanding universe. Currently, he is an assistant professor at the Enrico Fermi Institute at the College of the University of Chicago.

Carroll’s lecture, although intensely mathematical, was directed to a general audience. "The plan of the talk is to start at the very beginning where you know nothing about cosmology and to tell you enough so that at the end of the talk we will be at the furthest esoteric regions of current research." Beginning with a basic timeline of the history of the universe, Carroll described the evolution of both the universe and matter. Throughout the lecture Carroll explicated the basis of all cosmology and astrophysics, that the universe is homogeneous and isotropic, that is to say, space looks the same in all directions, devoid of any vector that points in a preferred place in space.

Once the universe is known to be homogeneous and isotropic there are only three possibilities for the geometry of space: Space could be flat, positively curved or negatively curved. These facts accompanied with the knowledge that space is expanding and was smaller in the past, thanks to Edwin Hubble-- another famous University of Chicago professor, lead to the question of the speed of the accelerating universe. Carroll proceeded to discuss the different methods and theories for research on the expanding universe.

"A preponderance of evidence favors an accelerating universe. I choose the words carefully: in a criminal court to convict somebody you have to prove beyond a reasonable doubt that they have committed a crime. We have not reached that standard of evidence yet, with the accelerating universe. We cannot send it to jail for accelerating. In a civil court, to win damages, you need only show that a preponderance of evidence indicates that the event occurred, and that we have reached. The evidence is pointing in that direction. We could collect civil damages from the universe, but not send it to jail."

Carroll attained a doctorate in cosmology from the Harvard-Smithsonian Center for Astrophysics. He then entered into the realm of post-doctoral research at the Center for Theoretical Physics at MIT, where he worked with the world-renowned physicist Alan Guth on theories of time travel. His penultimate stop, to date, was at the Institute for Theoretical Physics at the University of California, Santa Barbara.