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Special seminar </div>
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Tuesday 18 November 3pm, Physics B17 </div>
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José Padua-Argüelles (Perimeter Institute and University of Waterloo)</div>
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Title: Entropies for gravitational systems from simplicial Lorentzian path integrals</div>
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Abstract: Recent advances have argued how gravitational entropies can be computed directly from Lorentzian path integrals, avoiding the problems of Euclidean methods associated with the conformal factor problem that makes a path integral over Euclidean geometries
manifestly ill defined. In particular, the de Sitter horizon entropy can be recovered from a real-time path integral that computes the dimension of the Hilbert space associated with a spatial ball. Similarly, the swap entropy of an evaporating black hole (central
to the replica paradigm resolution of the black hole information paradox) can be computed in this way. Quantum Regge Calculus, a lattice-like approach to quantum gravity, enables concrete realizations of these scenarios, providing insights beyond continuum
methods. This perspective clarifies aspects of gravitational path integrals and may have implications for approaches such as causal dynamical triangulations and spin foams, where Regge-like formulations play a fundamental role.</div>
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<span style="color: rgb(0, 0, 0);">| Jorma Louko</span></p>
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<span style="color: rgb(0, 0, 0);">| School of Mathematical Sciences</span></p>
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<span style="color: rgb(0, 0, 0);">| University of Nottingham Tel: +44 115 95 14942</span></p>
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<span style="color: rgb(0, 0, 0);">| Nottingham NG7 2RD jorma.louko@nottingham.ac.uk</span></p>
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<span style="color: rgb(0, 0, 0);">| United Kingdom www.nottingham.ac.uk/mathematics</span></p>
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