## Search

Now showing items 1-10 of 25

#### Limits on a Gravitational Field Dependence of the Proton{Electron Mass Ratio from H2 in White Dwarf Stars

(American Physical SocietyPhysical Review Letters, 2014-09-18)

Spectra of molecular hydrogen (H2) are employed to search for a possible proton-to-electron
mass ratio (μ) dependence on gravity. The Lyman transitions of H2, observed with the Hubble
Space Telescope towards white dwarf ...

#### Redshifting of cosmological black bodies in BSBM varying-alpha theories

(APSPHYSICAL REVIEW D, 2014-12-04)

We analyse the behaviour of black-body radiation in theories of electromagnetism which allow
the electron charge and the fine structure constant to vary in space and time. We show that such
theories can be expressed as ...

#### Maximum Tension: with and without a cosmological constant

(OUPMonthly Notices of the Royal Astronomical Society, 2014-12-04)

We discuss various examples and ramifications of the conjecture
that there exists a maximum force (or tension) in general relativistic
systems. We contrast this situation with that in Newtonian gravity,
where no maximum ...

#### Dynamical symmetries in Brans-Dicke cosmology

(American Physical SocietyPhysical Review D, 2017-01-20)

In the context of generalized Brans-Dicke cosmology we use the Killing tensors of the minisuperspace in order to determine the unspecified potential of a scalar-tensor gravity theory. Specifically, based on the existence ...

#### Probing the Gravitational Dependence of the Fine-Structure Constant from Observations of White Dwarf Stars

(Multidisciplinary Digital Publishing InstituteUniverse, 2017-06-01)

Hot white dwarf stars are the ideal probe for a relationship between the fine-structure constant and strong gravitational fields, providing us with an opportunity for a direct observational test. We study a sample of hot ...

#### Kinematics of Einstein-Cartan universes

(American Physical SocietyPhysical Review D - Particles, Fields, Gravitation and Cosmology, 2017-05-08)

We analyze the kinematics of cosmological spacetimes with nonzero torsion, in the framework of the classical Einstein-Cartan gravity. After a brief introduction to the basic features of spaces with nonvanishing torsion, ...

#### Evolution of cyclic mixmaster universes with noncomoving radiation

(American Physical SocietyPhysical Review D, 2017-12-15)

We study a model of a cyclic, spatially homogeneous, anisotropic mixmaster universe of Bianchi type IX 'mixmaster' universe, containing the a radiation field with non-comoving ('tilted' with respect to the tetrad frame of ...

#### Cosmological models in energy-momentum-squared gravity

(American Physical SocietyPhysical Review D, 2017-12-15)

We study the cosmological effects of adding terms of higher-order in the usual energy-momentum tensor to the matter lagrangian of general relativity. This is in contrast to most studies of higher-order gravity which focus ...

#### Large-scale stability and astronomical constraints for coupled dark-energy models

(American Physical SocietyPhysical Review D, 2018-02-26)

The physics of the dark energy and the dark matter is still an open issue in cosmology. The dark energy occupies
about 68.5% of the total energy density of the universe today [1], and is believed to accelerate its observed ...

#### Evolution of initially contracting Bianchi Class A models in the presence of an ultra-stiff anisotropic pressure fluid

(Institute of PhysicsClassical and Quantum Gravity, 2016-05-12)

We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether ...