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SUMMARY:Quantum reference frames for gravity - Caslav Brukner\, University
  of Vienna
DTSTART:20230511T131500Z
DTEND:20230511T141500Z
UID:TALK196012@talks.cam.ac.uk
CONTACT:Damian Pitalua-Garcia
DESCRIPTION:We have no experimental knowledge about whether spacetime and 
 gravity exhibit quantum phenomena or not. In this talk\, I propose an "ext
 ended symmetry principle" that states that dynamical laws are invariant wh
 en changing quantum reference frames. This principle alone implies that sp
 acetime can be placed in a quantum superposition. We study two concrete si
 tuations: a clock near a gravitational source that is in spatial superposi
 tion\, and a superposition of conformally related spacetime metrics inhabi
 ted by a massive quantised Klein-Gordon field. We construct the explicit q
 uantum frame changes and\, invoking the extended symmetry principle\, show
  how to transform to a quantum frame in which the standard theories of gen
 eral relativity and quantum field theory allow the dynamics to be determin
 ed.
LOCATION:Zoom
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