Physics Colloquia

How to Give a Talk
Dr. Jean Creighton
Director of the UWM Manfred Olson Planetarium

Giving an engaging talk takes more than just knowing your material.

In this talk, I’ll outline key steps for preparing and delivering a compelling presentation for a variety of audiences. We’ll explore how to understand your listeners, define the purpose of your talk, clarify your message with visuals and explanations, rehearse effectively, engage your audience, and market your talk to generate interest. These strategies will help make your presentation more impactful and enjoyable for everyone involved.

Altermagnets: A New Technologically Relevant Class of Quantum Magnets
Daniel Agterberg
Professor, University of Wisconsin-Milwaukee

Magnetism underpins much of our current information technology. It also derives purely from quantum mechanics. Traditionally, discussion emphasizes two classes of magnets: usual ferromagnets, which underly data storage devices, and antiferromagnets, in which magnetic moments adopt an up-down structural motif. Recently, a new class of magnets, altermagnets, has generated tremendous interest. This class mixes properties of ferromagnets and antiferromagnets in a way that is promising for future applications.

From Extreme Binary Stars to Self-Driving Cars
Dr. Tony Rodriguez
Data Scientist, Waymo LLC (formerly Harvard CfA)

Compact objects -- white dwarfs (WDs), neutron stars, and black holes -- are laboratories for studying extreme physics under conditions unable to be replicated on Earth. When located in binaries, it becomes possible to measure properties of compact objects such as magnetic field strength, temperature, and the effects of mass transfer from a companion. In this talk, I will describe recent advancements in our understanding of WD magnetism.

Solving Atomic Structures of Molecules and Nanoclusters Using Superfluid Helium Droplet Cooling and Laser Alignment
Wei Kong
Department Head & Professor, Department of Chemistry - Oregon State University

We are building a prototype experimental apparatus to determine the atomic structures of molecules and nanoclusters using electron diffraction. We use superfluid helium droplets for cooling, thereby achieving effective field-induced orientation and alignment of the sample species. Electron diffraction patterns from the chosen orientation can then be accumulated until a satisfactory signal-to-noise ratio can be obtained.

How Dark is Space?
Tod R. Lauer
Astronomer, NOIRLab

We used NASA’s New Horizons spacecraft to measure the cosmic optical background (COB) intensity integrated over 0.4 ≲ λ ≲ 0.9 μm. The survey comprises 16 high Galactic-latitude fields. Images were obtained with the LORRI camera when New Horizons was 57 AU distant from the Sun. As such, the sky intensity measurements were unaffected by zodiacal light, which strongly interferes with COB measurements attempted from the inner solar system. T he survey yields a highly significant detection (6.8σ) of the COB at 11.16 ± 1.65 (1.47 sys, 0.75 ran) nW m−2 sr−1 at the LORRI pivot wavelength of 0.608 μm. The estimated integrated intensity from background galaxies, 8.17 ± 1.18 nW m−2 sr−1, can account for the great majority of this signal. The rest of the COB signal is formally classified as anomalous intensity but is not significantly different from zero. The simplest interpretation is that the COB is completely due to galaxies.

Better Together: Combining the Strengths of Rubin, Euclid, and Roman for Time-domain Science and Cosmology
Charlotte Ward
Assistant Professor, Department of Astronomy and Astrophysics in the Eberly College of Sciences at Penn State

We have entered an exciting decade for survey science, with space-based surveys such as Euclid and Roman and ground-based surveys such as Rubin Observatory's Legacy Survey of Space and Time (LSST) providing overlapping imaging datasets across the optical and IR. LSST will identify thousands of tidal disruption events (TDEs) and millions of AGN and supernovae – including hundreds of gravitationally lensed supernovae (gLSNe) from which we can measure the Hubble Constant.

Bringing XFEL Science to the Laboratory: Commissioning the Compact X-ray Light Source at Arizona State University
Sabine Botha, Research Assistant Professor, Department of Physics
Arizona State University

Compact accelerator-driven X-ray sources are emerging as a new class of laboratory-scale facilities capable of delivering capabilities traditionally available only at large national user facilities. At Arizona State University, the Compact X-ray Light Source (CXLS) is currently undergoing commissioning, while its successor, the Compact X-ray Free Electron Laser (CXFEL), is under construction. Together, these instruments aim to bring ultrashort, high-brightness X-ray pulses into the university laboratory, enabling new opportunities in structural biology, medical imaging, atomic, molecular and optical physics, and the study of condensed matter and quantum materials.

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.