Abstract
For a given asymptotically flat initial data set for Einstein equations a new geometric invariant is constructed. This invariant measures the departure of the data set from the stationary regime; it vanishes if and only if the data are stationary. In vacuum, it can be interpreted as a measure of the total amount of radiation contained in the data.
- Received 14 July 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.231101
©2004 American Physical Society