Ideal black hole gas

The concept of a primordial blackhole fluid with intrinsic spin density is examined along with its consequence for supercluster-sized, i.e., large scale voids, and the missing mass question

Application of Parametrized Post-Newtonian Methods to the Gravitational IS of Satellite Energy Exchange Data

Project Satellite Energy Exchange (SEE) is a free-flying, high altitude satellite that utilizes space to construct a passive, low-temperature, nano-g environment in order to accurately measure the poorly known gravitational constant G plus other gravitational parameters that are difficult to measure in an earth-based laboratory. Eventually data received from SEE must be analyzed using a model of the gravitational interaction including parameters that describe deviations from general relativity and experiment. One model that can be used to fit tile data is the Parametrized post- Newtonian (PPN) approximation of general relativity (GR) which introduces ten parameters which have specified values in (GR). It is the lowest-order, consistent approximation that contains non linear terms. General relativity predicts that the Robertson parameters, gamma (light deflection), and beta (advance of the perihelion), are both 1 in GR. Another eight parameters, alpha(sub k), k=1,2,3 and zeta(sub k), k=1,2,3,4 and Xi are all zero in GR. Non zero values for alpha(sub k) parameters predict preferred frame effects; for zeta(sub k) violations of globally conserved quantities such as mass, momentum and angular momentum; and for Xi a contribution from the Whitehead theory of gravitation, once thought to be equivalent to GR. In addition, there is the possibility that there may be a preferred frame for the universe. If such a frame exists, then all observers must measure the velocity omega of their motion with respect to this universal rest frame. Such a frame is somewhat reminiscent of the concept of the ether which was supposedly the frame in which the velocity of light took the value c predicted by special relativity. The SEE mission can also look for deviations from the r(exp -2) law of Newtonian gravity, adding parameters alpha and lamda for non Newtonian behavior that describe the magnitude and range of the r(exp -2) deviations respectively. The foundations of the GR supposedly agree with Newtonian gravity to first order so that the parameters alpha and lamda are zero in GR. More important, however, GR subsequently depends on this Newtonian approximation to build up the non linear higher-order terms which forms the basis of the PPN frame work

Inflation in Einstein-Cartan theory with energy-momentum tensor with spin

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic (Bianchi Type I) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley (RS) improved energy-momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density

Inevitable inflation in Einstein-Cartan theory with improved energy-momentum tensor with spin

Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic, (Bianchi Type-1) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley improved energy momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density. Shear is not effective in preventing inflation in the ECRS model. The relation between fluid vorticity, torsion, reference axis rotation, and shear ellipsoid precession shows through clearly

Minimal coupling of electromagnetic fields in Riemann–Cartan space‐times for perfect fluids with spin density

The electromagnetic field is minimally coupled to gravity in a Riemann–Cartan space‐time containing a charged magnetized spinning fluid. It is required that the overall Lagrangian of the gravitational field, spinning matter, and the electromagnetic field be invariant under a gauge transformation of the vector potential. The theory preserves both charge conservation and particle number conservation. The electromagnetic field, via the vector potential, now interacts directly with the spin energy momentum. The spin transport equation, in addition to the usual Fermi–Walker transport term, contains a contribution due to the torque of the electromagnetic field acting on a magnetic dipole. In the absence of electromagnetism, the field equations reduce to those of the usual self‐consistent Lagrangian formalism for a perfect fluid with spin density.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71126/2/JMAPAQ-33-3-1073-1.pd

Raychaudhuri equation in the self-consistent Einstein-Cartan theory with spin-density

The physical implications of the Raychaudhuri equation for a spinning fluid in a Riemann-Cartan spacetime is developed and discussed using the self-consistent Lagrangian based formulation for the Einstein-Cartan theory. It was found that the spin-squared terms contribute to expansion (inflation) at early times and may lead to a bounce in the final collapse. The relationship between the fluid's vorticity and spin angular velocity is clarified and the effect of the interaction terms between the spin angular velocity and the spin in the Raychaudhuri equation investigated. These results should prove useful for studies of systems with an intrinsic spin angular momentum in extreme astrophysical or cosmological problems

Spin fluid spacetimes from static general relativistic solutions

A method for generating spin fluid solutions to the field equations in a Riemann-Cartan spacetime is presented. The method uses any general relativistic static perfect fluid solution as input. The resulting RC solutions are irrotational and stationary. They will support a nonzero spin density. The spin density has zero Fermi derivative and will not contribute to a circulation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49193/2/cq930516.pd

Spinning fluid cosmologies in Einstein-Cartan theory

We consider self-consistent spinning fluid cosmologies in both general relativity in Riemannian spacetimes and Einstein-Cartan theory in Riemann-Cartan spacetimes. First we extend slightly the cosmological calculation of Martin et al for general relativistic self-consistent spinning fluids. The existence of spin-squared terms in the field equations in the Einstein-Cartan theory shows, however, that an expanded class of meaningful cosmologies is possible. Under certain assumptions on the arbitrariness of the cosmological shear and expansion the results for the ad hoc Weyssenhoff spin fluid in a spherically symmetric spacetime can be reproduced.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49195/2/cq940917.pd

String fluid dynamical models in the Einstein-Cartan theory

Using the general, energy-momentum tensor for a dynamical, string fluid developed from the Ray-Hilbert variational principle, physically motivated applications to Riemann-Cartan spacetime are given within the framework of the Einstein-Cartan theory. The string density is considered for the cases when it is or is not a thermodynamical variable of the fluid. Solutions are given for both cases and compared with other models in both general relativity and the Einstein-Cartan theory. The use of a string fluid as a contributer to galactic halo density is also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49200/2/q90325.pd

Energy conditions in non-Riemannian spacetimes

We interpret the energy conditions in non-Riemannian spacetimes by applying them to a family of stationary, axially symmetric solutions for the gravitational field equations for an Einstein-Cartan theory in a Riemann-Cartan spacetime.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31126/1/0000023.pd