Covariant Theory Of Gravitation Research Articles

Scale Covariant Gravitation - Part Six - Stellar Structure and Evolution

view Abstract Citations (4) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Scale Covariant Gravitation - Part Six - Stellar Structure and Evolution Canuto, V. M. ; Hsieh, S. H. Abstract Using the scale covariant theory of gravitation, we derive results of interest to stellar structure and evolution. We first derive the radiative transport equation which finds an immediate application in the study of stellar evolution with a variable gravitational "constant" G. We show that the Sun's absolute luminosity scales as L ∼ GM/κ, where κ is the stellar opacity. Taking into account that the Earth-Sun distance is also affected by a variable G, it is then shown that the Earth's effective temperature scales like Teff (G2M/κ)1/4. Comparisons with previous estimates, based on simple Newtonian framework, are presented and discussed. A third result that follows from this analysis is that a polytropic equation of state of the form p ∼pγ is incompatible with a variable G, the correct result being p ∼pγ(G/β2)γ-1, where β is the gauge function relating atomic to gravitational times. Finally, we derive a formula for the age of globular clusters as a function of G, using the previously derived expression for the absolute luminosity. Numerical estimates are presented. Publication: The Astrophysical Journal Pub Date: September 1981 DOI: 10.1086/159204 Bibcode: 1981ApJ...248..801C full text sources ADS |

Primordial nucleosynthesis and Dirac's large numbers hypothesis

Consideration is given to the analysis of Falik (1979) which attempted to show that the cosmological model proposed by Canuto and Hsieh (1978) in which the gravitational constant varies with time contradicts observations of primordial helium. It is shown that the analysis was based on the assumptions that (1) the energy density of radiation in local thermodynamic equilibrium is approximately equal to the fourth power of the equilibrium temperature, where the product of the equilibrium temperature with the scale factor of the Robertson-Walker metric is constant, and (2) the gravitational constant is approximately equal to the inverse of the time even at early cosmological epochs. These assumptions are demonstrated to be invalid in the scale covariant theory of gravitation used to develop the model, thus negating the conclusion that the Canuto and Hsieh model excludes the primordial synthesis of helium.

Time-dependent cosmological constant

Within the framework of the gauge covariant theory of gravitation it is showed that a time-dependent cosmological constant arises quite naturally as a result of Weyl conformai symmetry broken by quantum effects.

Consistency of Weyl's geometry as a framework for gravitation

Recent work, quoted in the introduction, concerning a scale covariant theory of gravitation and corresponding astrophysical tests, has called for a revival of the geometrical considerations put forward by Weyl half a century ago, together with a better understanding of the mathematical foundation of Weyl's geometry. The present paper is to be regarded as a contribution in that direction.

A covariant theory of gravitation

It is shown thnt a bimetric theory of gravitation incorporating the covariance and equivalence principles can be set up, which leads to many of the results of the general theory of relativity, but which has a much simpler mathematical structure. The theory under consideration makes use of a Riemannian metric tensor g/sub uv/ and an axially flat-space metric tensor gamma /sub uv/. (LBS)

A note on the nonlinear effect in the Lorentz covariant theory of gravitation

A note on the nonlinear effect in the Lorentz covariant theory of gravitation