Abstract: The cross-disciplinary field of biophysics is growing rapidly, and new opportunities to study biophysics are being developed here at Bucknell. But what, exactly, does a physicist have to offer to the study of life? I will say a bit about the methods developed and used by biophysicists, but I will primarily address this question by leading a tour through the cell from the perspective of a physicist, highlighting the roles played electric forces, work and energy, and entropy.

Abstract: Populations of individuals often migrate or divide into new territory. Such range expansions occur in microbial colonies, expanding animal populations, viral infections, etc. In many cases, the individuals at the population frontier have to compete for space. The competition and the shape of the frontier have dramatic consequences for the evolutionary dynamics of the population. We study the survival probability of mutations occurring at inflating frontiers which increase in size over time. A frontier inflates, for example, when the population is spreading out radially. We find that inflating frontiers can enhance mutation survival probability by orders of magnitude relative to frontiers that stay the same size. Finally, we consider the fate of a population undergoing irreversible, deleterious mutations. These mutations can lead to a loss of the fittest members of the population. The loss occurs more readily in spatially distributed populations.

Abstract: The fundamental symmetries required for identical particles in quantum mechanics have thermodynamic implications. These manifest themselves in things like the rigidity of solid matter, white dwarf and neutron stars, and Bose-Einstein condensation. I will use insights from elementary quantum mechanics to analyze the origin of what are often referred to as degeneracy pressure and fermion repulsion.

Abstract: Biology utilizes energy to organize itself from the nanoscale to the macroscopic scale. We seek to determine the universal principles of organization from the molecular scale that give rise to architecture on the cellular scale. We are specifically interested in the organization of the microtubule cytoskeleton, a rigid, yet versatile network in most cell types. Microtubules in the cell are organized by motor proteins and crosslinkers. This work applies the ideas of statistical mechanics and condensed matter physics to the non-equilibrium pattern formation behind intracellular organization using the microtubule cytoskeleton as the building blocks. We examine these processes in a bottom-up manner by adding increasingly complex protein actors into the system. Our systematic experiments expose nature’s laws for nanoscale to micron scale organization and have large impacts on biology as well as illuminating new frontiers of non-equilibrium physics. Much of the work I will be sharing was done by undergraduate researchers.

Abstract: MoNDian dark matter (MDM) is a new form of dark matter that naturally accounts for Milgrom’s scaling, usually associated with modified Newtonian dynamics (MoND), and theoretically behaves like cold dark matter (CDM) at cluster and cosmological scales. The original proposal for MDM is based on the intriguing relationship between gravity and thermodynamics, and was, in part, inspired by Verlinde's work on entropic gravity. In this talk, I will discuss the theoretical background for MDM and observational tests at galactic and cluster scales.

Abstract: Founded over a century ago, statistical mechanics for systems in thermal equilibrium has been so successful that, nowadays, it forms part of a typical physics core curriculum. On the other hand, most of “real life” phenomena occur under non-equilibrium conditions. Unfortunately, statistical mechanics for such systems is far from being well established. The goal of understanding complex collective behavior from simple microscopic rules (of evolution, say) remains elusive. As an example of the difficulties we face, consider predicting the existence of a tree from an appropriate collection of H,C,O,N,... atoms! Over the last two decades, an increasing number of condensed matter theorists are devoting their efforts to this frontier. After a brief summary of the crucial differences between text-book equilibrium statistical mechanics and non-equilibrium statistical mechanics, I will give a bird’s-eye view of some key issues, ranging from the “fundamental” to (a small set of) the “applied.” The methods used also span a wide spectrum, from simple computer simulations to sophisticated field theoretic techniques. These will be illustrated in the context of an overview of our work, as well as a simple model for transport.

Abstract: Dynamical Systems, Chaos theory and Complex Systems theory has some useful mathematical tools to bring to bear on problems that are very familiar to our own lives. Furthermore, social media has some really relevant large scaled data that also lends toward a modern discussion of what happens when people socially contact.