Today

  • The Einstein-Euler system with a physical vacuum boundary in spherical symmetry

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    General Relativity Seminar Speaker: Marcelo Disconzi, Vanderbilt University Title: The Einstein-Euler system with a physical vacuum boundary in spherical symmetry Abstract: We establish local well-posedness for the Einstein-Euler system with a physical vacuum boundary in spherical symmetry. Our proof relies on a new way of thinking about Einstein’s equations in spherical symmetry that is well-adapted […]

  • Mass for the large and for the small

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    General Relativity Seminar Speaker: Tin Yau Tsang, Courant Institute, New York University Title: Mass for the large and for the small Abstract: Seeking a meaningful geometric (physical) invariant to describe a spacetime has sparked research in both mathematics and physics. In this talk, we will first see the fundamental progress made by Schoen-Yau and Witten […]

  • The Einstein-Vlasov system in a large data regime

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    https://youtu.be/gtvSMhYhD3w General Relativity Seminar Speaker: Nikolaos Athanasiou, University of Crete, Greece Title: The Einstein-Vlasov system in a large data regime Abstract: In this talk, our object of study is the Einstein-Vlasov system with a massless Vlasov matter field. Complementing various important works obtaining the stability of Minkowski spacetime as a solution to this system, we […]

  • The mass angular momentum inequality

    Virtual

    General Relativity Seminar Speaker: Gilbert Weinstein, Ariel University Title: The mass angular momentum inequality Abstract: We show that either there is a counterexample to black hole uniqueness, in the form of a regular axisymmetric stationary vacuum spacetime with an asymptotically flat end and multiple degenerate horizons which is ‘ADM stable’, or the following statement holds. […]

  • On the past maximal development of near-FLRW data for the Einstein scalar-field Vlasov system

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    General Relativity Seminar Speaker: Liam Urban (University of Vienna) Title: On the past maximal development of near-FLRW data for the Einstein scalar-field Vlasov system Abstract: In recent years, the formation of Big Bang singularities has been increasingly well understood in presence of scalar-field matter, which suppresses the geometric oscillations that one generically expects otherwise. From a cosmological perspective, […]

  • General Relativity Seminar

    Virtual

    https://youtu.be/T9D4heG-OSU General Relativity Seminar Speaker: Maximilian Ofner, University of Vienna Title: Stability and Instability of Relativistic Fluids in Slowly Expanding Spacetimes Abstract: Homogeneous and isotropic solutions to the relativistic Euler equations are known to be unstable on a Minkowski background. However, for FLRW models with a fast expansion rate, relativistic fluids stabilize. This scenario suggests […]

  • BKL bounces outside homogeneity

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    https://youtu.be/g8V7VeQwDtk General Relativity Seminar Speaker: Warren Li ( Princeton University) Title: BKL bounces outside homogeneity Abstract: In work spanning the late 20th century, physicists Belinski, Khalatnikov and Lifshitz (BKL) proposed a general ansatz for solutions to the Einstein (vacuum) equations near singularities. They suggest that the spacetime dynamics at different spatial points on the singularity decouple […]

  • Positive scalar curvature with point singularities

    CMSA Room G10 CMSA, 20 Garden Street, Cambridge, MA, United States

    https://youtu.be/m9B003wQ0PY General Relativity Seminar Speaker: Rudolf Zeidler, Mathematical Institute, University of Münster Title: Positive scalar curvature with point singularities Abstract: I will explain a certain topological construction of positive scalar curvature metrics with uniformly Euclidean ($L^\infty$) point singularities. This provides counterexamples to a conjecture of Schoen. It also shows that there are metrics with uniformly Euclidean […]

  • Unstable Fluids in Expanding Cosmologies

    Virtual

    https://youtu.be/2Aak8YqVsLw General Relativity Seminar Speaker: Elliot Marshal, School of Mathematics at Monash University Title: Unstable Fluids in Expanding Cosmologies Abstract: The FLRW solution is the simplest cosmological model in general relativity, describing a fluid-filled, spatially homogeneous universe. While there is extensive literature in the physics community on cosmological models with a linear equation of state , […]

  • Low-regularity Local Well-posedness of the Elastic Wave System

    Virtual

    General Relativity Seminar Speaker: Sifan Yu, National University of Singapore Title: Low-regularity Local Well-posedness of the Elastic Wave System Abstract: In this talk, I will present a recent work on the elastic wave system in three spatial dimensions. For admissible harmonic elastic materials, we prove a low-regularity local well-posedness result for the corresponding elastic wave equations. For such materials, we can split the […]

  • Positive mass theorem for ALE(AE) and ALF(AF) Toric 4-Manifolds

    CMSA G102 20 Garden Street, Cambridge, MA

    General Relativity Seminar Speaker: Aghil Alaee, Clark University Title: Positive mass theorem for ALE(AE) and ALF(AF) Toric 4-Manifolds Abstract: One of the fundamental conjectures in mathematical relativity is the positivity of total mass (if it is defined!) for complete non-compact Riemannian manifolds assuming appropriate lower bounds on scalar curvature. This conjecture has been proved for […]

  • Hyperbolic equations in a double null gauge

    CMSA G102 20 Garden Street, Cambridge, MA

    General Relativity Seminar Speaker: Christopher Stith, University of Michigan Title: Hyperbolic equations in a double null gauge Abstract: The hyperbolic nature of the Einstein equations is well-known and has been used in many different contexts. More recently, the double null gauge has proven to be a powerful tool for quantitative analysis of the Einstein equations. It has […]