1999/06/07 by P. P. Avelino, C. J. A. P. Martins · 6 citations
Mathematics · Physics and Astronomy · #Advanced Differential Geometry Research #Black Holes and Theoretical Physics #Classical mechanics #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Covariance #Covariant transformation #Flatness (cosmology) #Four-force #General relativity #Gravitation #Invariant (physics) #Lorentz covariance #Lorentz transformation #Mathematical physics #Mathematics #One-way speed of light #Physics #Quantum mechanics #Test theories of special relativity #Theoretical physics #Theory of relativity #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1016/s0370-2693(99)00694-2
published as Phys.Lett. B459 (1999) 468-472 · 4 LaTeX pages, no figures. To appear in Phys. Lett. B
arxiv created 1999/06/07 · openalex publication_date 1999/07/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We propose a new generalisation of general relativity which incorporates a variation in both the speed of light in vacuum (c) and the gravitational constant (G) and which is both covariant and Lorentz invariant. We solve the generalised Einstein equations for Friedmann universes and show that arbitrary time-variations of c and G never lead to a solution to the flatness, horizon or Λ problems for a theory satisfying the strong energy condition. In order to do so, one needs to construct a theory which does not reduce to the standard one for any choice of time, length and energy units. This can be achieved by breaking a number of invariance principles such as covariance and Lorentz invariance.