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SUMMARY:Supertranslation\, angular momentum\, and covariance in 4d asympto
 tically flat space
DTSTART:20260409T123000Z
DTEND:20260409T143000Z
DTSTAMP:20260511T011300Z
UID:indico-event-51086@agenda.infn.it
DESCRIPTION:Speakers: Massimo Porrati (Istituto Nazionale di Fisica Nuclea
 re)\n\nThis talk reviews some aspects of the "angular momentum problem" in
  general relativity as well as of old and new results in the search for co
 variant and supertranslation-invariant formulas for the flux of angular mo
 mentum and other Lorentz charges in asymptotically flat spacetimes. It add
 resses in particular three problems with all existing solutions: 1) Supert
 ranslation-invariance and covariance imply invariance under spacetime tran
 slations\; 2) the flux depends on redundant auxiliary degrees of freedom t
 hat cannot be set to zero in all Lorentz frames without breaking Lorentz c
 ovariance\; 3) supertranslation-invariant Lorentz charges do not generate 
 the transformations of the Bondi mass aspect implied by the isometries of 
 the asymptotic metric. The resolution of these problems leads to new\, cov
 ariant formulas for the fluxes that make explicit the choice of reference 
 frame underpinning seemingly unambiguous results presented in the current 
 literature. This choice will be described in some detail and  an elementa
 ry method for measuring the rotational part of the angular momentum aspect
  will be presented.\n\nhttps://agenda.infn.it/event/51086/
URL:https://agenda.infn.it/event/51086/
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