Events

Title: Splitting the electron: Emergent phenomena in many-anyon systems

Please join us as collaborators, former students, and family remember the life and career of Professor Allen M. Goldman (1937-2025), whose career in the School of Physics spanned over 50 years. A reception with light refreshments follows. 

Title: he Ionization States and Dust Contents of High-Redshift Galaxies from Keck and JWST Spectroscopy

Abstract: A key goal of JWST is to explore the connection between massive stars and the state and contents of the ISM across cosmic history.  First, I will discuss the dependence of ionization parameter on metallicity and gas density.  Recent analyses using Keck and JWST spectroscopy demonstrate the importance of gas density in setting the physical conditions of the ISM at high redshift, and suggest a redshift invariance of the connection between gas density and ionization parameter between redshift z~2 to z~6, and possibly up to z~9.  Second, I will present new constraints on the shapes of the nebular dust attenuation curves and dust covering fractions from JWST/NIRSpec spectroscopy of HI Balmer and Paschen emission lines in z=2-4 galaxies.  I will discuss a few implications of the dust attenuation curves, including their affect on star-formation rates and some common emission lines ratios used to determine chemical abundances at high redshift.

Title: Using Data Science (AI/ML) to Discover Quantum Materials

Abstract: Solid state physics thrives on creating experimental realizations of predicted quantum states of matter, and on unexpected observations leading to new insights into the nature of the universe. In this talk, I will present an overview of quantum materials -- matter in which quantum fluctuations dominate the observed properties -- and how our understanding and ability to create such materials by design has changed with time. I will spend some time highlighting recent efforts by my group and others in the community to harness recent advances in data science (popularized as AI/ML) in order to accelerate the discovery of superconductors, and provide an outlook on how these tools might shape future research in solid state physics and beyond. If time permits, I will highlight connections between quantum materials discovery and recent efforts to understand and detect dark matter.

Title: The Spectral Revolution at Cosmic Dawn: Interpreting High-Redshift JWST Observations with Next-Generation Models

Abstract: JWST has revealed a remarkably diverse population of high-redshift galaxies, reshaping our understanding of early galaxy formation. However, interpreting these spectral data presents a fundamental theoretical challenge. In this talk, I will highlight key early JWST results and the limitations of existing models in extracting physical properties from spectra. I will introduce a new suite of simulations that incorporate non-equilibrium primordial, metal, and molecular chemistry alongside on-the-fly radiation transfer. These next-generation models enable first-principles forward modeling of JWST observations, offering new insights into the physical processes governing the formation and evolution of the first galaxies.

Title: "The Physics of the Cult Movie Interstellar"

Abstract: Christopher Nolan’s cult science fiction film Interstellar (2014) sprang from a treatment co-authored by physicist Kip Thorne, and so had real science — both firm and speculative — embedded in it from the outset.  The film’s venue is The Warped Side of our Universe:  objects and phenomena made, at least in part, from warped spacetime, such as black holes, wormholes, spacetime singularities, time travel, gravitational lensing, gravitational slingshots, solitary ocean waves driven by tidal gravitational forces, and braneworlds (general relativity in five macroscopic spacetime dimensions).  In this colloquium, Thorne (who was Interstellar’s executive producer and science advisor)  will discuss the science and scientific speculations underlying the movie, its visual effects, and connections to contemporary physics issues.

Speaker: Professor Kip Thorne, California Institute of Technology

The William I. Fine Theoretical Physics Institute is proud to host the 18th Annual Misel Family Public Lecture. This lecture is FREE AND OPEN TO THE PUBLIC. Questions? Please contact us at [email protected] or 612-625-6055. We look forward to seeing you there!

Abstract: In 1964, when Thorne was a student, there were hints that our universe might have a Warped Side:  Objects and phenomena made from warped space and warped time instead of from matter.  Thorne and his colleagues have spent these past sixty years turning those hints into clear understanding.  They have explored the Warped Side through theory (using mathematics and computer simulations to probe what the laws of physics predict) and through astronomical observations (primarily with gravitational waves). In this lecture he will describe what they have learned about Warped-Side phenomena:  black holes, wormholes, gravitational waves, our universe’s big-bang birth, and the possibility of time travel.

Please register through the UMN Events Calendar (registration is encouraged but not required).

Title: The Baryon Cycle in Action: Gas Recycling and Metallicity Trends in the ISM and CGM of Galaxies

Abstract: The formation and evolution of galaxies is governed by the baryon cycle — an intricate interplay of gas inflows, outflows, star formation, feedback, and recycling. Understanding this cycle requires tracing the evolution of metallicity and gas content in both the interstellar medium (ISM) and the circumgalactic medium (CGM). In this talk, I will present results from the MUSE Ultra Deep Field (MUDF), which enable us to probe the metallicity evolution and mass dependence of low-mass (M~10^7Msun), low star-formation rate (SFR~0.1Msun/yr) galaxies out to redshift z~2. The MUDF also includes two bright quasars at z~3.2, separated by ~500 kpc, whose sightlines intersect the IGM and CGM of these galaxies. This configuration allows us to directly connect galaxy properties observed in emission with gas seen in absorption. We find compelling evidence for gas recycling in the CGM of galaxies with high specific star-formation rates. I will also present new results from the KCWI Analysis of Gas around Galaxies (KAGG) survey, which significantly expands the sample of galaxies associated with absorption systems. In particular, we focus on Damped Lyman-alpha systems (DLAs), which trace large reservoirs of neutral hydrogen and provide robust metallicity diagnostics. Our findings show that these galaxies are detected at large impact parameters, suggesting extended distributions of neutral gas and confirming that high-redshift DLAs are integral components of the CGM. Finally, using the Qz5 survey of z~5 quasars, we examine the metallicity evolution of DLAs and the CGM. We confirm a steepening in metallicity decline beyond z > 4.7 and report, for the first time, that the cosmic HI mass density peaks at z~3–4. As expected, this is earlier in time than the peak in the star-formation rate density and molecular hydrogen mass density. These results provide critical constraints for future simulations of galaxy formation and the baryon cycle across cosmic time.

Title: New developments in oxide superconductors – the role of inherent inhomogeneity

Abstract: Superconductivity has been a major scientific topic for more than a century, yet in many important materials the emergence of this macroscopic quantum phenomenon remains poorly understood. Recent charge transport and thermodynamic measurements have revealed unusual yet universal superconducting fluctuation behavior in four well-known families of perovskite oxides – strontium titanate, strontium ruthenate, the bismuthates, and the cuprates – for which the superconducting pairing mechanisms are thought to differ. Complementary neutron and x-ray scattering measurements support the notion that both the electronic and structural order parameters in these materials couple to an underlying “hidden” inhomogeneity that is distinct from conventional point disorder, and that rare-region effects play a prominent role. These findings have far-reaching implications for the interpretation of electronic properties of perovskites in general, including thin films and heterostructures. In the case of the cuprates, inherent inhomogeneity constitutes a pivotal part of a robust phenomenological model that comprehensively captures hitherto elusive properties of the normal and superconducting states.

Title: The Curious Case of EP241021a

Abstract: Fast X-ray Transients (FXTs) are rare and poorly understood, with various potential progenitors. The launch of the Einstein Probe (EP) mission has greatly increased the rate of real-time FXT discoveries and enabled timely multi-wavelength follow-up observations. We have recently begun to do follow-up observations of FXTs with the Three Channel Imager (3KK) on the Fraunhofer Telescope at Wendelstein Observatory (FTW), located in the German Alps and operated by the Ludwig-Maximilians-Universität München.

EP241021a was the first FXT that we observed in this new campaign. The optical and NIR (OIR) counterpart shows a very peculiar panchromatic behavior in its light curve, rebrightening by almost 1.5 mag within ~2 days 5.5 days after the initial trigger. This event stands out due to its extreme brightness, peaking at an absolute magnitude of approximately -22 mag in the r band after rebrightening, and its consistently red color of J - r ≈ 1 mag. While its overall light curve can be described by two decaying power laws ~t^-1 with a steep rising phase ~t^4, its brightness and timescale distinguish it from other FXTs, including EP240414a, which exhibited similar behavior but evolved more rapidly and at lower luminosity. These characteristics, along with the absence of a gamma-ray detection, constrain possible origins for this event.

In this talk, I will discuss possible explanations for the extreme rebrightening. Traditional supernova models struggle to account for both the high luminosity and rapid evolution of EP241021a, but alternative scenarios related to the collapse of a massive star may offer a more promising explanation.