Dust in the York Canonical Basis of ADM Tetrad Gravity: the Problem of Vorticity

TL;DR

This paper extends Brown's perfect fluid formulation to ADM tetrad gravity, providing a Hamiltonian description of dust in the York basis, highlighting inertial gauge variables, and exploring linearization for cosmological applications.

Contribution

It introduces a Hamiltonian framework for dust in ADM tetrad gravity within the York basis, separating inertial and physical variables, and discusses linearization for cosmological studies.

Findings

Hamiltonian description of dust in York basis obtained

Identification of irrotational dust motions and gauge fixings

Analysis of Hamiltonian Post-Minkowskian linearization

Abstract

Brown's formulation of dynamical perfect fluids in Minkowski space-time is extended to ADM tetrad gravity in globally hyperbolic, asymptotically Minkowskian space-times. For the dust we get the Hamiltonian description in closed form in the York canonical basis, where we can separate the inertial gauge variables of the gravitational field in the non-Euclidean 3-spaces of global non-inertial frames from the physical tidal ones. After writing the Hamilton equations of the dust, we identify the sector of irrotational motions and the gauge fixings forcing the dust 3-spaces to coincide with the 3-spaces of the non-inertial frame. The role of the inertial gauge variable York time (the remnant of the clock synchronization gauge freedom) is emphasized. Finally the Hamiltonian Post-Minkowskian linearization is studied. The future application of this formalism will be the study of cosmological back-reaction (as an alternative to dark energy) in the York canonical basis.