scholarly journals A GRAVITATIONAL FIELD EQUATION WITH HIGHER ORDER DERIVATIVES AND IT'S SPHERICALLY SYMMETRIC STATIC SOLUTIONS

1979 ◽  
Vol 28 (5) ◽  
pp. 143
Author(s):  
SHEY YONG-CHENG
2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Genly Leon ◽  
John D. Barrow

AbstractWe study the Einstein-aether theory in Weyl integrable geometry. The scalar field which defines the Weyl affine connection is introduced in the gravitational field equation. We end up with an Einstein-aether scalar field model where the interaction between the scalar field and the aether field has a geometric origin. The scalar field plays a significant role in the evolution of the gravitational field equations. We focus our study on the case of homogeneous and isotropic background spacetimes and study their dynamical evolution for various cosmological models.


2014 ◽  
Vol 24 (01) ◽  
pp. 1550002 ◽  
Author(s):  
S. Thirukkanesh ◽  
M. Govender ◽  
D. B. Lortan

We present a new family of spherically symmetric, static solutions of the Einstein field equations in isotropic, comoving coordinates. The radial pressure at each interior point of these models vanishes yet equilibrium is still possible. The constant density Florides solution which describes the gravitational field inside an Einstein cluster is obtained as a special case of our solution-generating method. We show that our solutions can be utilized to model strange star candidates such as Her. X-1, SAX J1808.4-3658(SS2), SAX J1808.4-3658(SS1) and PSR J1614-2230.


Author(s):  
Bahram Mashhoon

In extended general relativity (GR), Einstein’s field equation of GR can be expressed in terms of torsion and this leads to the teleparallel equivalent of GR, namely, GR||, which turns out to be the gauge theory of the Abelian group of spacetime translations. The structure of this theory resembles Maxwell’s electrodynamics. We use this analogy and the world function to develop a nonlocal GR|| via the introduction of a causal scalar constitutive kernel. It is possible to express the nonlocal gravitational field equation as modified Einstein’s equation. In this nonlocal gravity (NLG) theory, the gravitational field is local, but satisfies a partial integro-differential field equation. The field equation of NLG can be expressed as Einstein’s field equation with an extra source that has the interpretation of the effective dark matter. It is possible that the kernel of NLG, which is largely undetermined, could be derived from a more general future theory.


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