Speaker: Yoon-Joo Kim (Columbia University)Title: The Néron model of a Lagrangian fibrationAbstract:Singular fibers in minimal elliptic fibrations were classified by Kodaira and Néron in the 1960s. In his proof, Néron constructed and systematically used a special group scheme acting on an elliptic fibration. This group scheme is now called the Néron model. A Lagrangian fibration is a higher-dimensional generalization of an elliptic fibration. Néron’s theory is restricted to 1-dimensional bases, so one cannot use Néron’s original approach to study higher-dimensional Lagrangian fibrations. The higher-dimensional analog of Néron’s definition was recently proposed by David Holmes. Quite unfortunately, Holmes also showed that such a generalized Néron model often fails to exist, even in simple cases. In this talk, we show that Holmes’s generalized Néron model does exist for an arbitrary projective Lagrangian fibration of a smooth symplectic variety, under a single assumption that the Lagrangian fibration has no fully-nonreduced fibers. This generalizes Néron’s result to many higher-dimensional Lagrangian fibrations. Such a construction has several applications. First, it extends Ngô's results on Hitchin fibrations to many Lagrangian fibrations. Second, it allows Lagrangian fibrations to be considered as a minimal model-compactification of a smooth commutative group scheme-torsor. Third, it provides a tool to study birational behaviors of Lagrangian fibrations. Finally, the notion of a Tate-Shafarevich twist can be understood via the Néron model.

Speakers: Jared Speck (Vanderbilt University)Title: The Einstein-Euler Free Boundary Problem in Spherical SymmetryAbstract: I will discuss my forthcoming paper with M. Disconzi on spherically symmetric solutions to the Einstein–Euler equations. The main result is local well-posedness for a class of initial data satisfying the physical vacuum condition. Our work provides the first rigorous existence result for a model of a dynamic, self-gravitating relativistic gaseous star with compact spatial support.

From the 1960s through the mid-1980s, phone phreaks and computer hackers authored piercing critiques of U.S. political economy, especially the telephone lines and computer networks that served as its central nervous system. But as hackers interacted with the companies, regulators, and professionals who governed the system, hackers integrated themselves into the system as experts, professionals, and reformers—and by the 1990s, the system welcomed their arrival.Presented by:JACOB BRUGGEMANPh.D. candidate, Department of History, Johns Hopkins University

Speaker: Duojia Pan, UT Southwestern Medical CenterHost: The Postdoctoral AssociationTitle: "Solid-like condensates of tumor suppressor protein Merlin/NF2 in Hippo pathway regulation"The Biology Colloquium is a weekly seminar held throughout the academic year — featuring distinguished speakers in many areas of the biological sciences from universities and institutions worldwide. More information on speakers, their affiliations, and titles of their talks will be added as available. Unless otherwise stated, the Colloquium will be held live in Stata 32-123 (Kirsch auditorium) Contact Margaret Cabral with questions.

Speaker: Sean Howe (University of Utah)Title: Sideways equidistribution of function field L-functionsAbstract:In the first part of this talk, we will explain a concise description of the asymptotic distributions of eigenvalues of Haar-random orthogonal matrices using a new $\sigma$-moment generating function that replaces the usual exponential with the plethystic exponential of symmetric function theory. Similar descriptions can be obtained also for compact symplectic, unitary, and symmetric groups.In the second part of the talk, we will explain how to use point-counting techniques to compute, for a fixed finite field $\mathbb{F}_q$, the distribution of the zeroes of the $L$-function of a random smooth degree $d$ surface in $\mathbb{P}^3_{\mathbb{F}_q}$ as $d ightarrow \infty$. The result is a simple description of the asymptotic $\sigma$-moment generating function. Comparing this with our description of the asymptotic distribution of the eigenvalues of a Haar-random orthogonal matrix, we obtain an equidistribution result that is "sideways" compared to the equidistribution results obtained by Katz and Sarnak, i.e. where the order of the limits in $d$ and $q$ have been exchanged. This sideways equidistribution is finer in that it sees the stable cohomology of local systems in all degrees instead of just the zeroth degree needed to compute monodromy.The techniques used are robust and apply also to the L-functions of more general smooth hypersurface sections, as well as some simple Dirichlet characters that were previously studied by Bergström-Diaconu-Petersen-Westerland. Time permitting, we will briefly discuss further generalizations and related work in progress joint with Bertucci / Bilu / Bilu and Das.

This talk will be a radical exploration of how higher education can advance transformative climate justice.Amid the worsening climate crisis and intensifying inequities, higher education can play a powerful role in addressing the intersecting crises facing humanity. Institutions of higher education hold untapped potential to advance social justice and reduce climate injustices. However, universities are not yet structured to accelerate social change for the public good.In Climate Justice and the University, Jennie Stephens, Professor of Climate Justice at the National University of Ireland Maynooth and a professor at Northeastern University (currently on leave), reimagines the potential of higher education to advance human well-being and promote ecological health. She will be introduced by John E. Fernández, director of the MIT Environmental Solutions Initiaitve, and converse with Naomi Oreskes, the Henry Charles Lea Professor of the History of Science and Affiliated Professor of Earth and Planetary Sciences at Harvard University.Books will be available for sale!Register here: https://docs.google.com/forms/d/e/1FAIpQLSfpiM-a3jvi5xiyTWdWgxBTi-y8h0TmuwTy8Q5_x891GZOuNA/viewform