APL Colloquium

April 21, 2017

Colloquium Topic: Are Fundamental Constants Actually Constant? Nuclear Physics and the Oklo Natural Nuclear Reactors

Text books are filled with tables of physical constants. Some like c, h or G we think of as “fundamental” because we don’t think they can be derived from any theory; they’re just given to us as parameters in our universe. How certain is it that they are constant, and is it actually possible to tell if they have changed with time? These questions are of interest since Dirac first suggested G might have evolved over the age of the universe, and recently have become even more so as the multiverse has emerged as an answer to why our present universe is so compatible with life. We’ll briefly review some of the numerical accidents that lead to the existence of our present universe; discuss whether you could ever detect a dimensional constant changing (answer: no!), and then go over the fascinating story of the Oklo nuclear reactors and the answer they give on the question of whether Coulomb’s law has changed over the last two billion years.

Colloquium Speaker: Chris Gould

Chris Gould is an Alumni Distinguished Undergraduate Professor of Physics Emeritus at North Carolina State University. He served for a decade as Department Head of Physics and later served for seven years as Associate Dean in the College of Sciences and a year as Interim Head of Biological Sciences. He is a nuclear physicist by training, with interests in cosmology, energy research, and science education. He is a Fellow of the American Physical Society, and as a member of the KamLAND collaboration, was co-recipient of the 2016 Breakthrough prize in fundamental physics “For the fundamental discovery and exploration of neutrino oscillations”.