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PERIMETER INSTITUTE RECORDED SEMINAR ARCHIVE

PIRSA:15030075  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Even a tiny cosmological constant casts a long shadow
Speaker(s): Abhay Ashtekar
Abstract:

Surprisingly, several basic questions in classical and quantum gravity, which were resolved some 40-50 years ago for zero $Lambda$, still remain open in the $Lambda >0$ case. In particular, for $Lambda >0$, we still do not have a satisfactory notion of gravitational radiation or Bondi 4-momentum in exact general relativity, nor a positive energy theorem. Similarly, the standard constructions of `in' and `out' Hilbert spaces that we routinely use (e.g. in the analysis of black hole evaporation) do not extend to the $Lambda >0$ case. In this talk I will present some illustrative examples of these quandaries and introduce a systematic approach to resolve the open issues.

 

Date: 19/03/2015 - 1:00 pm
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