The densitized lapse ('Taub function') and the Taub time gauge in cosmology.
The role of the Taub time gauge in cosmology is linked to the use of the densitized lapse function instead of the lapse function in the variational principle approach to the Einstein equations. The spatial metric variational equations then become the Ricci evolution equations, which are then supplem...
Main Author: | |
---|---|
Format: | |
Language: | English |
Published: |
2004
|
Online Access: | http://ezproxy.villanova.edu/login?url=https://digital.library.villanova.edu/Item/vudl:177412 |
Summary: | The role of the Taub time gauge in cosmology is linked to the use of
the densitized lapse function instead of the lapse function in the variational
principle approach to the Einstein equations. The spatial metric
variational equations then become the Ricci evolution equations, which
are then supplemented by the Einstein constraints which result from the
variation with respect to the densitized lapse and the usual shift vector
field. In those spatially homogeneous cases where the least disconnect
occurs between the general theory and the restricted symmetry scenario,
the recent adjustment of the conformal approach to solving the initial
value problem resulting from densitized lapse considerations is seen to be
inherent in the use of symmetry-adapted metric variables. The minimal
distortion shift vector field is a natural vector potential for the new York
thin sandwich initial data approach to the constraints, which in this case
corresponds to the diagonal spatial metric gauge. For generic spacetimes,
the new approach suggests defining a new minimal distortion shift gauge
which agrees with the old gauge in the Taub time gauge, but which also
makes its defining differential equation agree with the vector potential
equation for solving the supermomentum constraint in any time gauge. |
---|