Positivity of the Bondi mass in Bondi's radiating spacetimes
arXiv:math/0604155
Abstract
We find two conditions related to the {\it news functions} of the Bondi's radiating vacuum spacetimes. We provide a complete proof of the positivity of the Bondi mass by using Schoen-Yau's method under one condition and by using Witten's method under another condition.
arXiv comment18 pages, final version. Rendiconti Lincei - Matematica E Applicazioni, to appear in 2006