J. Guven et N. Omurchadha, CONSTRAINTS IN SPHERICALLY SYMMETRICAL CLASSICAL GENERAL-RELATIVITY .2. IDENTIFYING THE CONFIGURATION-SPACE - A MOMENT OF TIME SYMMETRY, Physical review. D. Particles and fields, 52(2), 1995, pp. 776-795
We continue our investigation of the configuration space of general re
lativity begun in the preceding paper. Here we examine the Hamiltonian
constraint when the spatial geometry is momentarily static (MS). We b
egin with a heuristic description of the presence of apparent horizons
and singularities. A peculiarity of MS configurations is that not onl
y do they satisfy the positive quasilocal mass (QLM) theorem, they als
o satisfy its converse: the QLM is positive everywhere, if and only if
the (nontrivial) spatial geometry is nonsingular. We derive an analyt
ical expression for the spatial metric in the neighborhood of a generi
c singularity. The corresponding curvature singularity shows up in the
traceless component of the Ricci tenser. As a consequence of the conv
erse, if the energy density of matter is monotonically decreasing, the
geometry cannot be singular. A. supermetric on the configuration spac
e which distinguishes between singular geometries and nonsingular ones
is constructed explicitly. Global necessary and sufficient criteria f
or the formation of trapped surfaces and singularities are framed in t
erms of inequalities which relate some appropriate measure of the mate
rial energy content on a given support to a measure of its volume. The
sufficiency criteria are cast in the following form: if the material
energy exceeds some universal constant times the proper radius l(0) of
the distribution, the geometry will possess an apparent horizon for o
ne constant and a singularity for some other larger constant. A more a
ppropriate measure of the material energy for casting the necessary cr
iteria is the maximum value of the energy density of matter rho(max):
if rho(max)l(0)(2) < some constant the distribution of matter will not
possess a singularity for one constant and an apparent horizon for so
me other smaller constant. These inequalities provide an approximate c
haracterization of the singular (nonsingular) and trapped (nontrapped)
partitions on the configuration space. Their strength is gauged by ex
ploiting the exactly solvable piecewise constant density star as a tem
plate. Finally, we provide a more transparent derivation of the lower
bound on the binding energy conjectured by Arnowitt, Deser, and Misner
and proven by Bizon, Malec, and O Murchadha and speculate on possible
improvements.