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Varying Expansion Rates for Solar System

  1. Jan 3, 2005 #1
    Compared to the rest of the Universe:Sean M Carroll and Eugene A Lim.

    Quote:The different rescalings of Newton’s constant in the Solar System versus the universe as a whole offer a potential window for observational constraints on the parameters of our vector field. Newton’s constant enters cosmological observations in different ways, including measurements of the expansion rate in the present universe, the formation of late time large-scale structure (e.g [38]) and the properties of perturbations in the Cosmic Microwave Background. However, the most straightforward test comes from the predictions of primordial abundances from Big Bang nucleosynthesis (BBN). Changes to the effective value of Newton’s constant are equivalent to the presence of additional (or lack of some) radiation components, leading to a change in the rate of expansion.

    Also their conclusions state:We have found solutions to Einstein’s equation in the presence of other matter fields for a class of Lorentz-violating, fixed-norm vector field theories, and find that they act to rescale the value of Newton’s constant. By comparing these rescalings in the Newtonian regime
    to those in cosmology, we find an observable deviation from ordinary general relativity.
    Following this, we use the predictions of BBN to place constraints on the value of the norm of this vector field.
    Further constraints on this theory, in addition to those already cited in this paper on the βi’s, can be derived when we consider its perturbations. In particular, the presence of this vector field during inflation will modify the primordial spectrum of perturbations leading to observable features on both the temperature and polarization anisotropy spectra of the Cosmic Microwave Background. This investigation is the subject of a companion publication.

    Surely I have I read this wrong?..any deviation of Gravitational effects would be comparable to the Galaxy and Universe, NOT as to the Solar System and Universe?

    An expansion rate due to the the density of matter for our Solar System, must be coupled/offset, to the local expansion rate due to the 'local' Pressure purely from our Sun?
  2. jcsd
  3. Jan 4, 2005 #2


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    It would appear from your extract that they are comparing solar system observations, i.e. the standard GR and Newtonian tests, with cosmological deductions from BB nucleosynthesis etc.

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