BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Black holes and hot shells in the Euclidean path integral approach to quantum gravity DTSTART:20221006T143000Z DTEND:20221006T163000Z DTSTAMP:20260906T152438Z UID:e07a908e-f82e-4b43-af6a-9b63afd2b462 SEQUENCE:4 CREATED:20220930T080627Z DESCRIPTION:Abstract:Microscopic gravitational systems involving black hol es and matter present quantum and thermodynamic properties that are worth of study.Due to the breaking of the vacuum from a strong gravitational fie ld near the event horizon of a black hole\, particles\, such as gravitons or other matter fields\, are emitted to infinity with a definite temperatu re\, the Hawking temperature. Left by itself\, a black hole loses mass in this emission process until it eventually disappears.To understand more de eply the connection and conversion between black holes and hot matter fiel ds\, one has thus to enclose the black hole and the hot matter inside a he at reservoir which is maintained at constant temperature and constant radi us\, and which in turn characterizes the canonical ensemble of statistical mechanics. A thermodynamic treatment for the system black hole plus hot m atter is then possible. We model the hot matter fields by a hot thin shell that surrounds a black hole and is inside the heat reservoir.To work out the quantum partition function\, from which the thermodynamics of the syst em emerges\, we use the Euclidean path integral approach to quantum gravit y that identifies the path integral of the gravitational system with the p artition function itself. In a zeroth order\, semiclassical\, evaluation o f the path integral\, one computes the Euclidean classical action of the s ystem which\, at this order\, is equal to the system'\;s thermodynamic free energy divided by the temperature. Several important consequences re lated to the energy\, the temperature stratification\, the entropy\, and t he thermodynamic stability of the system unfold in a natural way.A most si gnificant result is the finding of the various possible thermodynamic phas es of the ensemble\, specifically\, pure black hole spaces\, pure hot shel l spaces\, hot shell with a black hole spaces\, and hot flat spaces\, and the establishing of the possible phase transitions between them through th e identification of the ground state phase of the ensemble once a temperat ure equation of state for the matter in the hot shell is given. Yet anothe r result connected with the conversion of pure black holes into curved spa ces with hot matter in the form of hot thin shells and vice versa\, is tha t the systems in some instances perform as black hole thermodynamic mimick ers and in another instance act as authentic dynamic and geometric mimicke rs. The precise setting and all these results will be explained in some de tail along the seminar. LAST-MODIFIED:20221003T143535Z LOCATION:Sala de Seminários do DF\, Pavilhão de Física\, 2º piso URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/black-holes-and-hot-shells -in-the-euclidean-path-integral-approach-to-quantum-gravity/ X-ALT-DESC;FMTTYPE=text/html:

Abstract:

Microscopic gravitational systems involving blac k holes and matter present quantum and thermodynamic properties that are w orth of study.

Due to the breaking of the vacuum from a strong gravitational field near the event horizon of a black hole\, particles\, such as gravitons or other matter fields\, are emitted to infinity with a definite temperature\, the Hawking temperature. Left by itself\, a black hole loses mass in this emission process until i t eventually disappears.

To underst and more deeply the connection and conversion between black holes and hot matter fields\, one has thus to enclose the black hole and the hot matter inside a heat reservoir which is maintained at constant temperature and co nstant radius\, and which in turn characterizes the canonical ensemble of statistical mechanics. A thermodynamic treatment for the system black hole plus hot matter is then possible. We model the hot matter fields by a hot thin shell that surrounds a black hole and is inside the heat reservoir.< br/>

To work out the quantum partition f unction\, from which the thermodynamics of the system emerges\, we use the Euclidean path integral approach to quantum gravity that identifies the p ath integral of the gravitational system with the partition function itsel f. In a zeroth order\, semiclassical\, evaluation of the path integral\, o ne computes the Euclidean classical action of the system which\, at this o rder\, is equal to the system'\;s thermodynamic free energy divided by the temperature. Several important consequences related to the energy\, t he temperature stratification\, the entropy\, and the thermodynamic stabil ity of the system unfold in a natural way.

A most significant result is the finding of the various possible th ermodynamic phases of the ensemble\, specifically\, pure black hole spaces \, pure hot shell spaces\, hot shell with a black hole spaces\, and hot fl at spaces\, and the establishing of the possible phase transitions between them through the identification of the ground state phase of the ensemble once a temperature equation of state for the matter in the hot shell is g iven. Yet another result connected with the conversion of pure black holes into curved spaces with hot matter in the form of hot thin shells and vic e versa\, is that the systems in some instances perform as black hole ther modynamic mimickers and in another instance act as authentic dynamic and g eometric mimickers. The precise setting and all these results will be expl ained in some detail along the seminar.

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