Events at Physics

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Events During the Week of October 30th through November 6th, 2022

Monday, October 31st, 2022

Plasma Physics (Physics/ECE/NE 922) Seminar
Isotope Mass Dependence of Turbulence and Transport in H-Mode Plasmas on DIII-D
Time: 12:00 pm
Place: 1610 Engineering Hall
Speaker: George McKee, UW Madison
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Tuesday, November 1st, 2022

Non-Partisan Voter Information Session
Time: 12:00 pm
Speaker: Susan Nossal
Abstract: You are invited to an informal discussion about non-partisan voting information on Tuesday, November 1st at noon via Zoom in advance of the Tuesday, November 8th election.

Early in-person absentee voting has begun in Madison, including on the UW-Madison campus.

We will discuss where to find information about topics such as:
• Eligibility for voting
• How to register to vote
• Voter ID requirements
• Obtaining a voter-compliant ID card (for UW students)
• Early in-person absentee voting opportunities on the UW Campus and elsewhere
• Finding poll locations for those voting on election day, Tuesday, November 8th
• How to find out what is on your ballot
• How to find information if voting in another state

A few resources for non-partisan voting information are the UW voter information site(, BadgersVote (,and the State of Wisconsin MyVote site ( The Morgridge Center for Public Service is hosting a VoteFest this week (

This will be an opportunity for us all to share information with each other. Please feel welcome to bring questions. If we don’t know the answers, we will try to point people to places where they may be able to get their questions addressed. If possible, it may be helpful to log on with a device that you can use to access various websites.
Everyone is welcome! Even if you are not eligible to vote, but you would like to learn more about the voting process in Wisconsin, please come. You are welcome to come late and leave early.
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Thesis Defense
Astophysical Neutrino Source Searches Using IceCube Starting Tracks
Time: 3:00 pm
Place: 4274 Chamberlin or
Speaker: Sarah Mancina, Physics Graduate Student
Abstract: The IceCube detector is an array of optical light detectors embedded deep in the South Pole ice that aims to discover the origins of astrophysical neutrinos. Due to the detector's location, the southern equatorial sky astrophysical neutrino signal lies under a large background of muons generated in cosmic ray interactions in the atmosphere. Therefore, IceCube’s sensitivity to astrophysical neutrino sources has always been stronger in the northern sky, where the main background is atmospheric neutrinos created by cosmic ray air showers.The research presented here focuses on improving IceCube’s sensitivity to southern sky sources by selecting for starting tracks, which are created by muon neutrinos that interact inside of the IceCube detector volume. By selecting for starting tracks, we not only reduce the atmospheric muon background but also the atmospheric neutrino background, allowing for a high purity sample of astrophysical neutrinos in the southern sky. The starting tracks were used to perform four types of searches for astrophysical neutrino sources: a whole sky neutrino source search, an individual source search with locations from bright gamma ray objects, a stacked source search which looks for a signal from multiple sources of the same type, and a galactic plane template search which looks for neutrinos created in the galactic plane medium. All searches were unable to significantly detect an astrophysical neutrino source, but the starting track selection technique could be used in tandem with other selections to discover galactic sources of neutrinos in the future.
Host: Albrecht Karle
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Theory Seminar (High Energy/Cosmology)
Gravitational production of scalar dark matter
Time: 4:00 pm
Place: Chamberlin 5280
Speaker: Sarunas Verner, University of Florida
Abstract: First, I discuss the out-of-equilibrium production of scalar dark matter (DM) from the inflaton condensate during inflation and reheating. Here I assume that this scalar dark matter is only minimally coupled to gravity and consider the regime of purely gravitational dark matter. For the purely gravitational regime, scalar dark matter quanta are copiously excited during inflation resulting in an infrared (IR) dominated distribution function and a relic abundance that overcloses the universe for a reheating temperature T_{reh} > 34 GeV. I discuss the reheating mechanism and compare perturbative and non-perturbative calculations of the energy density in radiation, and compare the resulting energy density based on these different approaches. I also briefly discuss the isocurvature constraints. This talk is based on arXiv:2206.08940 and arXiv:2109.13280.
Host: George Wojcik
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Wednesday, November 2nd, 2022

Physics ∩ ML Seminar
Bayesian Updating and dynamical flows
Time: 11:00 am
Place: Online Seminar: Please sign up for our mailing list at for zoom link
Speaker: David Berman, Queen Mary University
Abstract: Statistical Inference is the process of determining a probability distribution over the space of parameters of a model given a data set. As more data becomes available this probability distribution becomes updated via the application of Bayes’ theorem. We present a treatment of this Bayesian updating process as a continuous dynamical system. Statistical inference is then governed by a first order differential equation describing a trajectory or flow in the information geometry determined by a parametric family of models. We solve this equation for some simple models and show that when the Cram´er-Rao bound is saturated the learning rate is governed by a simple 1/T power-law, with T a time-like variable denoting the quantity of data. We illustrate this with both analytic and numerical examples based on Gaussians and the inference of the coupling constant in the Ising model. Finally we compare the qualitative behaviour exhibited by Bayesian flows to the training of various neural networks on benchmarked data sets such as MNIST and CIFAR10 and show how that for networks exhibiting small final losses the simple power-law is also satisfied.
Host: Gary Shiu
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GREAT IDEAS DEI coffee hour
Time: 12:15 pm
Place: Chamberlin 5280 or online at
Abstract: We will be discussing this paper by Appleby et al, Disciplinary significance of social caring in postsecondary science, technology, engineering, and mathematics. This is a longer article, so we are asking people to focus on these sections: Abstract, Introduction, III. A Case of University Students doing Physics (sections A, B and D), IV. Our Conjecture: Social Caring Supports a Shifted Epistemology (Section A), and Discussion and Implications.

GREAT IDEAS stands for Group for Reading, Educating, And Talking about Inclusion, Diversity, Equity, & Advocacy in Science. It is a multimedia reading group dedicated to amplifying the experiences of underrepresented groups in science and academia in order to become better advocates for our peers. GREAT IDEAS is open to everyone (students/ faculty/ staff/ etc), and all are welcome and encouraged to engage with the material and contribute to the discussions. To keep a welcoming and safe environment for everyone, we ask that everyone understand and adhere to our community guidelines for the discussions. If you would like to submit an article for a future GREAT IDEAS discussion, you can do so on this form.
Host: GMaWiP and Climate and Diversity Committee (contact Jessie Thwaites or R. Sassella with questions)
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Thursday, November 3rd, 2022

R. G. Herb Condensed Matter Seminar
Topological Superconductivity and the Braiding of Majorana Zero Modes in Magnet-Superconductor Hybrid Systems
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Dirk Morr, UIC
Abstract: Magnet-Superconductor Hybrid (MSH) systems have proven to be versatile platforms for the engineering of topological superconductivity and the ensuing Majorana zero modes, an important step towards the realization of topological quantum computing. In particular, the experimental ability to create MSH system with widely varying magnetic structures -- from ferromagnetic and skyrmion-like to antiferromagnetic – has provided an unprecedented opportunity to manipulate and explore topological phases. In this talk, I will review some recent progress in the theoretical prediction and experimental realization of novel topological superconducting phases – ranging from topological nodal-point superconductivity to higher order topological superconductors -- in MSH systems. Moreover, I will discuss how the real-time manipulation of the magnetic structure in MSH systems provides a new path to braiding MZMs, revealing their non-Abelian statistics, and to the creation of topological quantum gates.
Host: Robert Joynt
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IceCube webinar
Join IceCube as they announce exciting new results!
Time: 1:00 pm
Place: DeLuca Forum, Discovery Building or online at
Speaker: various, IceCube
Abstract: Join us to hear exciting IceCube results!

In person at the H.F. DeLuca Forum at the Discovery Building

Or via the zoom link –
Host: WIPAC/IceCube
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Astronomy Colloquium
How Circumgalactic Medium Dynamics Impact Galaxy Evolution
Time: 3:30 pm
Place: Sterling Hall 4421
Speaker: Dr. Cassi Lochhaas, Space Telescope Science Institute
Abstract: The region of space surrounding galaxies, the circumgalactic medium (CGM), is the site of all gas flows into and out of galaxies and therefore responsible for regulating or promoting galaxy growth. It has been only in the past couple decades that we have been able to observe this tenuous medium, and even more recently that we have been able to resolve it in cosmological simulations. I will discuss the classical theories for the CGM’s role in galaxy evolution and how my work has shown these theories need serious revision in light of new simulations. Using the Figuring Out Gas & Galaxies In Enzo (FOGGIE) simulations that resolve the CGM of Milky Way-like galaxies in exquisite detail, I will describe how dynamic gas motions in the CGM – turbulence, rotation, and bulk radial flows – drive the galactic ecosystem out of hydrostatic equilibrium and drive its temperature away from the virial temperature, ultimately affecting how galaxies accrete new gas to convert into stars. These results hint at a new paradigm of non-equilibrium galaxy evolution, where the commonly-assumed balance between gas flows and star formation in galaxies is actually an emergent phenomenon that appears only through averaging over large scales in space and time.
Host: Ke Zhang
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Friday, November 4th, 2022

Grad Town Hall
Time: 1:00 pm
Place: 2103 Chamberlin
Speaker: Kevin Black and Sharon Kahn, Physics Grad Program
Abstract: We invite you to join us for a Town Hall on Friday, Nov 4, 1-2pm, 2103 Chamberlin. This will be an open forum to ask questions and discuss issues. You are welcome to submit agenda/discussion items here: We’ll have some snacks – in order to be sure that we arrange enough food, RSVP to let us know that you plan to attend here:
Host: Kevin Black and Sharon Kahn
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Physics Department Colloquium
How do we know what we know? The importance of absolute anchors in cosmology
Time: 3:30 pm
Place: 2241 Chamberlin Hall
Speaker: Francis-Yan Cyr-Racine, University of New Mexico
Abstract: Since they naturally live in angular and redshift space, astronomical observations have a built-in invariance under rescaling all length scales in the problem. Breaking this invariance requires the use of anchors, such as known distances or energy scales, that can set the absolute scale of the problem. These anchors are fundamental to our knowledge of cosmological distances throughout the Universe, and provide the backbone on which much of our knowledge of cosmology rests. These pillars have recently come under renewed scrutiny due to apparently discrepant measurements of the Hubble constant, a very important cosmological quantity which sets the size and age of the observable Universe. Here, we carefully examine the key anchors underpinning observations of the cosmic microwave background and baryon acoustic oscillations, finding ways to detach these measurements from their traditional anchors and fully restore their intrinsic scaling invariance. Not only can this help to understand the possible cause of the Hubble constant discrepancy, but it also sheds new light on the origins of cosmological constraints on new physics beyond the Standard Model. This in turn provides us with a general toolbox to design novel cosmological models that are automatically compatible with observations. The lessons we draw here about fundamental measurement anchors have broad applications outside of cosmology and astrophysics.
Host: Moritz Muenchmeyer
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