BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Pedro Resende (Instituto Superior Técnico\, Lisbon) DTSTART:20210319T180000Z DTEND:20210319T184000Z DTSTAMP:20260423T024655Z UID:TQFT/34 DESCRIPTION:Title: An abstract theory of physical measurements\nby Pedro Resende (Instituto Superior Técnico\, Lisbon) as part of Topological Quantum Field Theory C lub (IST\, Lisbon)\n\n\nAbstract\nSince its early days\, quantum mechanics has forced physicists to consider the interaction between quantum systems and classically described experimental devices — a fundamental tenet fo r Bohr was that the results of measurements need to be communicated using the language of classical physics.\n\nSeveral decades of progress have led to improved understanding\, but the tension between “quantum” and “ classical” persists. Ultimately\, how is classical information extracted from a measurement? Is classical information fundamental\, as in Wheeler ’s “it from bit”? In this talk\, which is based on ongoing work [1]\ , I approach the problem mathematically by considering spaces whose points are measurements\, abstractly conceived in terms of the classical informa tion they produce. Concretely\, measurement spaces are stably Gelfand quan tales [2] equipped with a compatible sober topology\, but essentially thei r definition hinges on just two binary operations\, called composition and disjunction\, whose intuitive meanings are fairly clear. Despite their si mplicity\, these spaces have interesting mathematical properties. C*-algeb ras yield measurement spaces of “quantum type\,” and Lie groupoids giv e us spaces of “classical type\,” such as those which are associated w ith a specific experimental apparatus. The latter also yield a connection to Schwinger’s selective measurements\, which have been recast in groupo id language by Ciaglia et al.\nAn interaction between the two types\, prov iding a mathematical approach to Bohr’s quantum/classical split\, can be described in terms of groupoid (or Fell bundle) C*-algebras as in [3]. I will illustrate the basic ideas with simple examples\, such as spin measur ements performed with a Stern–Gerlach apparatus.\n\nReferences\n\n[1] P. Resende\, An abstract theory of physical measurements (2021)\, available at \nhttps://arxiv.org/abs/2102.01712.\n\n[2] P. Resende\, The many groupo ids of a stably Gelfand quantale\, J. Algebra 498 (2018)\, 197–210\, \nD OI 10.1016/j.jalgebra.2017.11.042.\n\n[3] P. Resende\, Quantales and Fell bundles\, Adv. Math. 325 (2018)\, 312–374\, \nDOI 10.1016/j.aim.2017.12. 001. MR3742593\n\nSecond part of a double session\, followed by a 20 minut e discussion period.\n LOCATION:https://researchseminars.org/talk/TQFT/34/ END:VEVENT END:VCALENDAR