Physics Colloquia

Uncovering Extreme Matter When Gravity Waves
Nicolas Yunes, Bob Uyetani Professor in Physics
University of Illinois Urbana-Champaign

Neutron stars contain matter at extreme densities and low temperatures that cannot be reproduced together in terrestrial experiments. Their collisions offer a way to study this matter through gravitational waves. In this colloquium, I will discuss how tidal deformation connects gravitational-wave measurements to stellar structure, and how approximate universal relations help overcome degeneracies in these measurements. I will then explore the connections between microscopic nuclear interactions and macroscopic stellar properties, asking what observations can tell us about matter deep inside neutron stars. A neutron star’s response does not just depend on its equilibrium structure, but also on how rapidly it is driven, how its constituents relax toward equilibrium, and how phase boundaries respond to perturbations. These effects connect dynamical tides and dissipation to the underlying matter physics. I will distinguish what observations already constrain from the signatures that remain difficult to measure, and discuss the prospects for learning more about dense matter when gravity waves.

Light-driven Molecular Transformations Captured by Ultrafast Spectroscopy
Dr. Chavdar Slavov, Assistant Professor, Department of Chemistry
University of South Florida

Femtosecond time-resolved spectroscopy reveals the excited-state pathways and chromophore dynamics that transform light absorption into photochemical and biological function. Using phytochromes, I will illustrate how the protein environment controls chromophore isomerization, which in turn initiates structural changes that regulate biological signaling.