Events at Physics |
Events During the Week of January 25th through February 1st, 2026
Monday, January 26th, 2026
- Theory Seminar (High Energy/Cosmology)
- Learning Fundamental Physics from Cosmological Probes: Neutrinos and the Cosmic Microwave Background
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5280
- Speaker: Gabriele Montefalcone, U. Texas, Austin
- Abstract: The cosmic microwave background (CMB) provides a unique window onto fundamental physics, allowing us to study particles and interactions that are otherwise extremely difficult to probe in laboratory experiments. One important example is the cosmic neutrino background, which influences the evolution of the early Universe, primarily through gravity despite interacting only very weakly with ordinary matter. In this talk, I will discuss how the free-streaming nature of neutrinos is expected to leave a subtle but distinctive imprint on the CMB by inducing a phase-shift in the acoustic oscillations of the photon–baryon plasma prior to recombination, providing a clean and robust probe of neutrino physics. I will present a framework to extract this effect directly from CMB observations, and show that current data from Planck, ACT, and SPT detect it with high significance, consistent with the Standard Model prediction of three free-streaming neutrino species. I will then discuss how the same measurement can be used to test beyond standard model scenarios in which neutrinos interact more strongly, delaying their decoupling from the primordial plasma. By directly relating the observed phase shift to neutrino interactions, cosmological data can place competitive constraints on new neutrino physics using this single, well-understood observable and without the need for dedicated model-dependent analyses.
- Host: Joshua Foster
Tuesday, January 27th, 2026
- Council Meeting
- Time: 3:00 pm - 4:00 pm
- Place: 2314 Chamberlin
- Speaker: Kevin Black
- Host: Kevin Black
Wednesday, January 28th, 2026
- Department Meeting
- Time: 12:15 pm - 1:15 pm
- Place: B343 Sterling
- Speaker: Kevin Black, UW - Madison, Department of Physics
- Department Meeting
- Host: Kevin Black
Thursday, January 29th, 2026
- Astronomy Colloquium
- What Are We Learning About Super-Eddington Accretion Disks From Simulations?
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Prof. Chris Fragile, College of Charleston
- Abstract: Accretion of gas onto black holes is one of the most important processes shaping our Universe. Understanding extremely high rates of accretion (dubbed `super-Eddington') is vital to explaining the challenging observation that supermassive black holes (SMBHs) are fully formed at redshifts >7. It is also important to understanding astrophysical objects such as tidal disruption events (TDEs) and ultra-luminous X-ray sources (ULXs). While we are able to perform observations of super-Eddington accreting systems, to understand them more fully, we must turn to numerical studies. In this talk, I will present the results of some recent super-Eddington disk simulations and discuss some of the interesting things we are learning.
- Host: Sebastian Heinz
Friday, January 30th, 2026
- Physics Department Colloquium
- Atomtricity: From Gauge Field Theory to Transistors for Matter Waves
- Time: 3:30 pm - 4:30 pm
- Place: Chamberlin 2241
- Speaker: Dana Z. Anderson, Infleqtion and University of Colorado, Boulder
- Abstract: Gauge fields arise within a rather abstract theoretical framework for addressing interactions among sets of identical particles; it is central particularly to high-energy particle physics and has recently become of interest to the AMO and quantum information physics communities. The canonical electronic transistor is a three-terminal device in which a weak signal can control a much stronger one. The transistor has a central role in nearly all modern electronics products. This talk takes a fast-moving yet scenic path starting with gauge field theory to describe the principles of transistors that operate on (ultracold) atoms rather than electrons. Historically gauge field theory was developed to understand the fundamental particles and forces of nature. Notably, Maxwell’s equations can be derived directly from a gauge field theory that incorporates the speed of light and the impedance of free space as empirical constraints (among a few others). Yet gauge field theory itself is agnostic as to whether particles and forces are or are not fundamental. We have applied it to identical neutral atoms that interact (such as ultracold 87Rb atoms) via van der Waals forces. Imposing the laws of non-relativistic quantum mechanics rather than the laws of Relativity as constraints to the theory leads to a set of matter wave duals to Maxwell’s equations. These ultimately lead to what one might refer to as the “laws of atomtricity” that are duals to the laws of electromagnetism. These laws enable one to define and study the mechanics of AC matter waves, i.e., waves that are associated with alternating particle currents. Their behavior is dramatically different than the more familiar matter waves associated with the time-independent Schrödinger equation. The laws of atomtricity naturally involve the concept of impedance, which concept leads to circuit elements, and particularly to transistors and transistor circuits that can be used to generate AC matter waves. Being an applied physicist, I cannot help but tell you how the new physics and matter wave circuits can be useful.
- Host: Mark Saffman