Physics Colloquia

Chuck Steidel, Caltech

Imaging the "Baryon Cycle" of Forming Galaxies

The rapid increase in the universal star formation density between z~6 and z~2 (12.5-10.5 Gyr ago) was driven by high rates of accretion onto galaxy-scale dark matter halos, but was simultaneously modulated by energetic feedback from massive stars, supernovae, and AGN activity whose large-scale effects remain uncertain. The competition between rapid accretion from the intergalactic medium and outflows driven by sources of energy and momentum originating near a galaxy's center is arguably the least well-understood aspect of the current galaxy formation paradigm.

Andrew Ferguson, University of Chicago

Reconstructing All-Atom Protein Folding from Low-Dimensional Experimental Time Series

Data-driven modeling and machine learning present powerful tools that are opening up new paradigms and opportunities in the understanding, discovery, and design of soft and biological materials. In the first part of this talk, I will describe an approach integrating ideas from dynamical systems theory and nonlinear manifold learning to reconstruct multidimensional protein folding funnels from the time evolution of single experimentally measurable observables.

Dr. Tomáš Bzdušek, Paul Scherrer Institute and University of Zurich

Mathematics of Topological Insulators and Semimetals

Many properties of crystalline materials, such as conductivity or the tendency to become magnetically ordered at low temperatures, derive from their so-called “electronic band structure.” Although this is an established notion in solid state physics, dating back to the early days of quantum mechanics, our understanding of electronic band structure has been greatly challenged and revolutionized over the past 15 years by the discovery of so-called topological materials.

Gregory Rudnick, University of Kansas

The Life Cycle of Galaxies in Clusters Over 10 Billion Years

Galaxies live in a range of environments, characterized by their volume density. For example, the densest regions of the Universe are in galaxy clusters, which contain hundreds to thousands of galaxies all in pseudo gravitational virial equilibrium. These dense environments can in turn alter the properties of the galaxies themselves in striking ways via a variety of gravitational and hydrodynamic processes. The result of these processes alter galaxy shapes, their internal dynamics, and shuts off the formation of new stars.

Wynn Ho, Haverford College

The Impact of Pulsar Glitches and NICER on Gravitational Wave Searches

Pulsars are the rotating remnant of massive stars and are unique probes of dense matter physics. They are famous for having very precisely measured spin rates, and this spin evolves extremely regularly for most pulsars. However, young pulsars can occasionally undergo sudden spin changes, known as glitches.

Deep Chatterjee, University of Wisconsin-Milwaukee PhD Candidate

Title and abstract TBA

Ionel Popa, UWM Physics Faculty

Title and abstract TBA

Michelle Larson, Adler Planetarium

Title and abstract TBA

Mark Williamsen, Quantum Design, Inc

Applications of AC Bridges in Cryogenic Measurements

AC (alternating current) bridges have proven to be useful in making precise measurements at low temperature, including thermometry as well as length change with respect to either thermal expansion (dilatometry) or applied magnetic field (magnetostriction). Techniques now in use allow one leg of the bridge to be placed at the cryogenic sample site while the other legs remain at room temperature, with the intervening temperature gradient being imposed along a length of coaxial cable.

Dr. Joshua "Shua" Sanchez, Postdoctoral Fellow, Department of Physics, MIT

Quantum Criticality and Magnetic Field-Induced Superconductivity

When electrons have strong interactions with each other, new quantum phases of matter emerge, such as magnetism, nematicity, charge order, and superconductivity. In these “Quantum Materials”, the microscopic interactions can be very difficult to probe and understand, yet they give rise to macroscopic properties that are easier to study and can be harnessed for new technologies.