Join us next Friday, October 24th, 12–1PM in 10-401 (Fish Bowl) for a talk with Brian Smith, Director of QLAB, and Alex Marshall, MIT MArch '13 alum and Vice President at Quarra Stone Company.Founded in 1989 with just six craftsmen, Quarra Stone Company has grown into one of the leading architectural stone fabricators in the U.S. Based in Madison, Wisconsin, Quarra bridges centuries-old craftsmanship with cutting-edge technology. From hand carving and 3D scanning to robotic milling and digital modeling.Their projects span from the U.S. Capitol to House of Horns by WOJR to contemporary art installations such as MIT’s own Officer Sean Collier Memorial, translating design intent into enduring material form. This work not only preserves stone’s ancient legacy but redefines its role in shaping today’s built environment.

*Special seminar: unusual time and locationSpeaker: Pierre Godfard (UNC Chapel Hill)Title: Rigidity of SU(2) quantum representations of mapping class groups at prime levelsAbstract:The property (T) conjecture for mapping class groups predicts that finite-dimensional unitary representations of mapping class groups of surfaces of genus at least 3 have no infinitesimal deformations (are rigid). This rigidity question has been extensively studied for finite image representations, where it is known as the Ivanov conjecture. A natural direction is to investigate infinite image unitary representations. Natural examples arise from unitary modular fusion categories via the Reshetikhin-Turaev construction, yielding what are called quantum representations of mapping class groups.For closed surfaces of genus at least 7, I will discuss rigidity of quantum representations arising from SU(2) and SO(3) modular categories at prime roots of unity. The strategy is to relate the problem to Ocneanu rigidity—a result asserting that modular fusion categories admit no non-trivial deformations. Ocneanu rigidity reduces our problem to constructing an injective map from deformations of the mapping class group representation in question to deformations of the modular fusion category. The construction uses modular functor theory and harmonic representatives from Hodge theory. Injectivity follows from a partial homological stability result for first cohomology groups of mapping class groups with coefficients in adjoints of SU(2) and SO(3) quantum representations.Zoom: https://mit.zoom.us/j/93615455445. For the Passcode, please contact Pavel Etingof at etingof@math.mit.edu.

Ten minutes for your mind@2:50 every day at 2:50 pm in multiple time zones:Europa@2:50, EET, Athens, Helsinki (UTC+2) (7:50 am EST) https://us02web.zoom.us/j/88298032734Atlantica@2:50, EST, New York, Toronto (UTC-4) https://us02web.zoom.us/j/85349851047Pacifica@2:50, PST, Los Angeles, Vancouver (UTC=7) (5:50 pm EST) https://us02web.zoom.us/j/85743543699Almost everything works better again if you unplug it for a bit, including your mind. Stop by and unplug. Get the benefits of mindfulness without the fuss.@2:50 meets at the same time every single day for ten minutes of quiet together.No pre-requisite, no registration needed.Visit the website to view all @2:50 time zones each day.at250.org or at250.mit.edu

Speaker: Yasuyuki Kawahigashi (University of Tokyo)Title: Modular invariance as completenessAbstract: We discuss the physical meaning of modular invariance for two-dimensional unitary conformal quantum field theories. For QFT models, while T invariance is necessary for locality, S invariance is not mandatory. The S invariance is a form of completeness of the theory that has a precise meaning as Haag duality for arbitrary multi-interval regions. We present a mathematical proof and its physical interpretation. For rational CFT's, the failure of modular invariance or Haag duality can be measured by an index, related to the quantum dimensions of the model. We show how to compute this index from the modular transformation matrices. This is a joint work with V. Benedetti, H. Casini, R. Longo, and J. M. Magan.Zoom: https://mit.zoom.us/j/93615455445. For the Passcode, please contact Pavel Etingof at etingof@math.mit.edu.

Mastering complexity at reacting electrode interfaces: from better batteries to high-performance CO2 capture-conversionBetar M. Gallant Kendall Rohsenow Associate ProfessorReactive interfaces are an inherent part of many key electrochemical decarbonization technologies and underpin their distinctive functions, from enabling the reversible cycling of unstable electrode materials in next-generation batteries to fine-tuning product selectivity in electrocatalytic reactions. In this talk, I will explore two examples that highlight how an unruly electrochemical interface—and the resulting device performance—can be powerfully modulated through the design of advanced electrolytes.First, I will discuss our efforts to identify quantitative, universal design descriptors of the lithium (Li) metal anode solid electrolyte interphase (SEI), which sensitively governs the Li Coulombic efficiency (CE), across diverse electrolyte classes and describe how these insights are unlocking new, high-performance electrolyte design strategies.Second, I will highlight our development of conversion processes that reduce CO₂ directly from the captured (liquid sorbent-bound) state, where selectivity for desired reduction products depends exquisitely on competition among multiple reactants at the electrode interface. Once revealed, this competition can be exploited to powerfully alter reaction outcomes.Bio: Betar M. Gallant obtained her SB (’08), SM (’10), and PhD (’13) degrees from the MIT MechE department, following which she was a Kavli Nanoscience Institute Postdoctoral Fellow at Caltech in the Division of Chemistry and Chemical Engineering. Her research group focuses on advanced chemistries and materials for high-energy primary and rechargeable batteries, including fluorinated cathode conversion reactions and lithium, sodium, and calcium metal anodes and their interfaces. Her group is also leading research into electrochemical CO2 capture including its integration with direct electrochemical conversion. She is the recipient of multiple awards including an Army Research Office Young Investigator Award, the NSF CAREER Award, The Electrochemical Society (ECS) Battery Division Early Career Award, an ECS-Toyota Young Investigator Award, the ACS Energy & Fuels Division Glenn Award, the ECS Charles W. Tobias Young Investigator Award, the MIT Faculty Founders $100k Breakthrough Prize, ACS Energy & Fuels Rising Star award, and the Ruth and Joel Spira Award for Distinguished Teaching at MIT. She is a co-founder of HaloGen Power, which is commercializing the highest-energy lithium primary battery to be brought to market based on chemistry developed in her group. Prof. Gallant is the Faculty Director for the MIT-GE Vernova Energy and Climate Alliance and also serves as the Energy Storage flagship lead for the Tata-MIT Alliance.

Join us in song! Come sing with the Concert Choir - Music will be provided for all!Lobby 10 "Memorial Lobby"Conducted by Ryan Turner.ABOUT MIT CONCERT CHOIRThe MIT Concert Choir, directed by Ryan Turner, is a large choral group open by audition to both graduate and undergraduate students, and to members of the MIT community. The Concert Choir is a social, academic and musical ensemble in which students learn and perform major works from the standard repertoire, as well as selected shorter and lesser-known pieces. Rehearsals culminate in a public performance each semester that is often accompanied by a professional orchestra and soloists. When appropriate, student soloists are also featured. You can find a more detailed history of MIT's Concert Choir here.