BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CMSA - ECPv6.15.18//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:CMSA
X-ORIGINAL-URL:https://cmsa.fas.harvard.edu
X-WR-CALDESC:Events for CMSA
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20210314T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20211107T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20220313T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20221106T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20230312T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20231105T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221208T093000
DTEND;TZID=America/New_York:20221208T103000
DTSTAMP:20260501T104900
CREATED:20230817T182138Z
LAST-MODIFIED:20240228T111217Z
UID:10001250-1670491800-1670495400@cmsa.fas.harvard.edu
SUMMARY:A new proof for the nonlinear stability of slowly-rotating Kerr-de Sitter
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Allen Fang (Princeton) \nTitle: A new proof for the nonlinear stability of slowly-rotating Kerr-de Sitter \nAbstract: The nonlinear stability of the slowly-rotating Kerr-de Sitter family was first proven by Hintz and Vasy in 2016 using microlocal techniques. In my talk\, I will present a novel proof of the nonlinear stability of slowly-rotating Kerr-de Sitter spacetimes that avoids frequency-space techniques outside of a neighborhood of the trapped set. The proof uses vector field techniques to uncover a spectral gap corresponding to exponential decay at the level of the linearized equation. The exponential decay of solutions to the linearized problem is then used in a bootstrap proof to conclude nonlinear stability.
URL:https://cmsa.fas.harvard.edu/event/gr_12822/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-12.08.22-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221117T093000
DTEND;TZID=America/New_York:20221117T103000
DTSTAMP:20260501T104900
CREATED:20230817T181725Z
LAST-MODIFIED:20240118T090857Z
UID:10001249-1668677400-1668681000@cmsa.fas.harvard.edu
SUMMARY:Ringdown and geometry of trapping for black holes
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Semyon Dyatlov (MIT) \nTitle: Ringdown and geometry of trapping for black holes \nAbstract: Quasi-normal modes are complex exponential frequencies appearing in long time expansions of solutions to linear wave equations on black hole backgrounds. They appear in particular during the ringdown phase of a black hole merger when the dynamics is expected to be driven by linear effects. In this talk I give an overview of various results in pure mathematics which relate asymptotic behavior of quasi-normal modes at high frequency to the geometry of the set of trapped null geodesics\, such as the photon sphere in Schwarzschild (-de Sitter). These trapped geodesics have two kinds of behavior: the geodesic flow is hyperbolic in directions normal to the trapped set (a feature stable under perturbations) and it is completely integrable on the trapped set. It turns out that normal hyperbolicity gives information about the rate of decay of quasi-normal modes\, while complete integrability gives rise to a quantization condition.
URL:https://cmsa.fas.harvard.edu/event/gr_111722/
LOCATION:Hybrid
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-11.17.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221110T093000
DTEND;TZID=America/New_York:20221110T103000
DTSTAMP:20260501T104900
CREATED:20230817T181337Z
LAST-MODIFIED:20240118T090553Z
UID:10001248-1668072600-1668076200@cmsa.fas.harvard.edu
SUMMARY:Schwarzschild-like Topological Solitons in Gravity
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Pierre Heidmann (Johns Hopkins) \nTitle: Schwarzschild-like Topological Solitons in Gravity \nAbstract: We present large classes of non-extremal solitons in gravity that are asymptotic to four-dimensional Minkowski spacetime plus extra compact dimensions. They correspond to smooth horizonless geometries induced by topology in spacetime and supported by electromagnetic flux\, which characterize coherent states of quantum gravity. We discuss a new approach to deal with Einstein-Maxwell equations in more than four dimensions\, such that they decompose into a set of Ernst equations. We generate the solitons by applying different techniques associated with the Ernst formalism. We focus on solitons with zero net charge yet supported by flux\, and compare them to Schwarzschild black holes. These are also ultra-compact geometries with very high redshift but differ in many aspects. At the end of the talk\, we discuss the stability properties of the solitons and their gravitational signatures.
URL:https://cmsa.fas.harvard.edu/event/gr_111022/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-11.10.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221103T103000
DTEND;TZID=America/New_York:20221103T113000
DTSTAMP:20260501T104900
CREATED:20230817T180818Z
LAST-MODIFIED:20240209T063325Z
UID:10001247-1667471400-1667475000@cmsa.fas.harvard.edu
SUMMARY:Asymptotic geometry of null hypersurface in Schwarzschild spacetime and null Penrose inequality
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Pengyu Le (BIMSA) \nTitle: Asymptotic geometry of null hypersurface in Schwarzschild spacetime and null Penrose inequality \nAbstract: Null Penrose inequality is an important case of the well-known Penrose inequality on a null hypersurface. It conjectures the relation between the area of the outmost marginally trapped surface and the Bondi mass at null infinity. Following the proposal of Christodoulou and Sauter\, we employ the perturbation method to study the asymptotic geometry of null hypersurfaces at null infinity in a perturbed vacuum Schwarzshild spacetime. We explain how to apply this perturbation theory to prove null Penrose inequality on a nearly spherically symmetric null hypersurface in a perturbed vacuum Schwarzschild spacetime.
URL:https://cmsa.fas.harvard.edu/event/gr_11322/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221027T103000
DTEND;TZID=America/New_York:20221027T113000
DTSTAMP:20260501T104900
CREATED:20230817T180439Z
LAST-MODIFIED:20240118T090238Z
UID:10001246-1666866600-1666870200@cmsa.fas.harvard.edu
SUMMARY:Gravitational Wave\, Angular Momentum\, and Supertranslation Ambiguity
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Naqing Xie (Fudan University) \nTitle: Gravitational Wave\, Angular Momentum\, and Supertranslation Ambiguity\n\nAbstract: The supertranslation ambiguity of angular momentum is a long-standing and conceptually important issue in general relativity. Recently\, there appeared the first definition of angular momentum at null infinity that is supertranslation invariant. However\, in the compact binary coalescence community\, supertranslation ambiguity is often ignored. We have shown that\, in the linearised theory of gravitational wave\, the new angular momentum coincides with the classical definition at the quadrupole level. This talk is based on a recent joint work with Xiaokai He and Xiaoning Wu.
URL:https://cmsa.fas.harvard.edu/event/gr_102722/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221020T103000
DTEND;TZID=America/New_York:20221020T113000
DTSTAMP:20260501T104900
CREATED:20240215T103645Z
LAST-MODIFIED:20240229T093550Z
UID:10002742-1666261800-1666265400@cmsa.fas.harvard.edu
SUMMARY:Love Symmetry of Black Holes
DESCRIPTION:General Relativity Seminar \nSpeaker: Sergei Dubovsky (New York University)\n\n\n\nTitle: Love Symmetry of Black Holes\n\n\nAbstract: Perturbations of massless fields in the Kerr-Newman black hole background enjoy a (“Love”) SL(2\,ℝ) symmetry in the suitably defined near zone approximation. We show how the intricate behavior of black hole responses in four and higher dimensions can be understood from the SL(2\,ℝ) representation theory. In particular\, static perturbations of four-dimensional black holes belong to highest weight SL(2\,ℝ) representations. It is this highest-weight property that forces the static Love numbers to vanish. We show that the Love symmetry is tightly connected to the enhanced isometries of extremal black holes. The Love symmetry also exhibits a peculiar UV/IR mixing.
URL:https://cmsa.fas.harvard.edu/event/gr_102022/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-10.20.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221013T103000
DTEND;TZID=America/New_York:20221013T233000
DTSTAMP:20260501T104900
CREATED:20240215T091921Z
LAST-MODIFIED:20240229T092506Z
UID:10002712-1665657000-1665703800@cmsa.fas.harvard.edu
SUMMARY:Strong Cosmic Censorship
DESCRIPTION:General Relativity Seminar \n\nSpeaker: Professor Oscar Dias (University of Southampton) \n\nTitle: Strong Cosmic Censorship \nAbstract: Generically\, strong cosmic censorship (SCC) is the statement that physics within general relativity should be predicted from initial data prescribed on a Cauchy hypersurface. In this talk I will review how fine-tuned versions of SCC have been formulated and evolved along the last decades up to the point where we believe that Christodoulou’s version is true in asymptotically flat spacetimes. However\, I will also describe that in recent years it was found that this is no longer necessarily true for some other backgrounds\, namely in some de Sitter (with a positive cosmological constant) spacetimes or even in rotating BTZ black holes in 3-dimensional Anti-de Sitter spacetime. Finally\, I will discuss some possibilities (quantum effects\, non-smooth initial data\,…) that might restore SCC in those backgrounds where the standard formulation of the conjecture is violated.
URL:https://cmsa.fas.harvard.edu/event/gr_101322/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221006T103000
DTEND;TZID=America/New_York:20221006T233000
DTSTAMP:20260501T104900
CREATED:20240215T092242Z
LAST-MODIFIED:20240229T092649Z
UID:10002715-1665052200-1665099000@cmsa.fas.harvard.edu
SUMMARY:Duality in Einstein’s Gravity
DESCRIPTION:General Relativity Seminar \nSpeaker: Uri Kol\, CMSA \n\nTitle: Duality in Einstein’s Gravity \nAbstract: Electric-Magnetic duality has been a key feature behind our understanding of Quantum Field Theory for over a century. In this talk I will describe a similar property in Einstein’s gravity. The gravitational duality reveals\, in turn\, a wide range of new IR phenomena\, including aspects of the double copy for scattering amplitudes\, asymptotic symmetries and more.
URL:https://cmsa.fas.harvard.edu/event/gr_10622/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220929T103000
DTEND;TZID=America/New_York:20220929T113000
DTSTAMP:20260501T104900
CREATED:20240216T091125Z
LAST-MODIFIED:20240229T111436Z
UID:10002755-1664447400-1664451000@cmsa.fas.harvard.edu
SUMMARY:General-relativistic viscous fluids
DESCRIPTION:General Relativity Seminar \nSpeaker: Marcelo Disconzi\, Vanderbilt University \nTitle: General–relativistic viscous fluids\n\nAbstract: The discovery of the quark-gluon plasma that forms in heavy-ion collision experiments provides a unique opportunity to study the properties of matter under extreme conditions\, as the quark-gluon plasma is the hottest\, smallest\, and densest fluid known to humanity. Studying the quark-gluon plasma also provides a window into the earliest moments of the universe\, since microseconds after the Big Bang the universe was filled with matter in the form of the quark-gluon plasma. For more than two decades\, the community has intensely studied the quark-gluon plasma with the help of a rich interaction between experiments\, theory\, phenomenology\, and numerical simulations. From these investigations\, a coherent picture has emerged\, indicating that the quark-gluon plasma behaves essentially like a relativistic liquid with viscosity. More recently\, state-of-the-art numerical relativity simulations strongly suggested that viscous and dissipative effects can also have non-negligible effects on gravitational waves produced by binary neutron star mergers. But despite the importance of viscous effects for the study of such systems\, a robust and comprehensive theory of relativistic fluids with viscosity is still lacking. This is due\, in part\, to difficulties to preserve causality upon the inclusion of viscous and dissipative effects into theories of relativistic fluids. In this talk\, we will survey the history of the problem and report on a new approach to relativistic viscous fluids that addresses these issues.
URL:https://cmsa.fas.harvard.edu/event/general-relativistic-viscous-fluids/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-09.29.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220922T103000
DTEND;TZID=America/New_York:20220922T113000
DTSTAMP:20260501T104900
CREATED:20240216T113602Z
LAST-MODIFIED:20240229T110700Z
UID:10002767-1663842600-1663846200@cmsa.fas.harvard.edu
SUMMARY:A scale-critical trapped surface formation criterion for the Einstein-Maxwell system
DESCRIPTION:General Relativity Seminar \n\n\nSpeaker: Nikolaos Athanasiou\n\nTitle: A scale-critical trapped surface formation criterion for the Einstein-Maxwell system\n\nAbstract: Few notions within the realm of mathematical physics succeed in capturing the imagination and inspiring awe as well as that of a black hole. First encountered in the Schwarzschild solution\, discovered a few months after the presentation of the Field Equations of General Relativity at the Prussian Academy of Sciences\, the black hole as a mathematical phenomenon accompanies and prominently features within the history of General Relativity since its inception. In this talk we will lay out a brief history of the question of dynamical black hole formation in General Relativity and discuss a result\, in collaboration with Xinliang An\, on a scale-critical trapped surface formation criterion for the Einstein-Maxwell system.
URL:https://cmsa.fas.harvard.edu/event/a-scale-critical-trapped-surface-formation-criterion-for-the-einstein-maxwell-system/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-09.22.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220915T103000
DTEND;TZID=America/New_York:20220915T113000
DTSTAMP:20260501T104900
CREATED:20240214T111637Z
LAST-MODIFIED:20240229T104038Z
UID:10002693-1663237800-1663241400@cmsa.fas.harvard.edu
SUMMARY:The Gregory-Laflamme instability of black strings revisited
DESCRIPTION:General Relativity Seminar\n\nTitle: The Gregory-Laflamme instability of black strings revisited\n \nAbstract: In this talk I will discuss our recent work that reproduces and extends the famous work of Lehner and Pretorius on the end point of the Gregory-Laflamme instability of black strings. We consider black strings of different thicknesses and our numerics allow us to get closer to the singularity than ever before. In particular\, while our results support the picture of the formation of a naked singularity in finite asymptotic time\, the process is more complex than previously thought. In addition\, we obtain some hints about the nature of the singularity that controls the pinch off of the string.
URL:https://cmsa.fas.harvard.edu/event/title-tba-3/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-09.15.22-1.png
END:VEVENT
END:VCALENDAR