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Review
. 2011;14(1):2.
doi: 10.12942/lrr-2011-2. Epub 2011 Mar 29.

Varying Constants, Gravitation and Cosmology

Jean-Philippe Uzan  1
Affiliations
Review

Varying Constants, Gravitation and Cosmology

Jean-Philippe Uzan. Living Rev Relativ. 2011.

Abstract

Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

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Figures

Figure 1
Figure 1
Top: Summary of the systems that have been used to probe the constancy of the fundamental constants and their position in a space-time diagram in which the cone represents our past light cone. The shaded areas represents the comoving space probed by different tests. Bottom: The look-back time-redshift relation for the standard ΛCDM model.
Figure 2
Figure 2
Evolution of the comparison of different atomic clocks summarized in Table 7.
Figure 3
Figure 3
Summary of the values of some coefficients entering the parameterization (70) and necessary to interpret the QSO absorption spectra data. From [367]
Figure 4
Figure 4
Summary of the direct constraints on αEM obtained from the AD (blue), MM (red) and AD (green) methods (left) and on μ (right) that are summarized in Table 10.
Figure 5
Figure 5
Left: Level scheme of nuclei participating to the 4He(αα, γ)12C reaction. Right: Central abundances at the end of the CHe burning as a function of δNN for a 60 M∩ star with Z = 0. From [103].
Figure 6
Figure 6
(Left): variation of the light element abundances in function of η compared to the spectroscopic abundances. The vertical line depicts the constraint obtained on η from the study of the cosmic microwave background data. The lithium-7 problem lies in the fact that ηspectro < ηwmap. From [107]. (right): Dependence of the light element abundance on the independent variation of the BBN parameters, assuming η = ηWMAP. From [105]
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References

    1. Accetta FS, Krauss LM, Romanelli P. New limits on the variability of G from big bang nucleosynthesis. Phys. Lett. B. 1990;248:146. doi: 10.1016/0370-2693(90)90029-6. - DOI
    1. Acquaviva V, Baccigalupi C, Leach SM, Liddle AR, Perrotta F. Structure formation constraints on the Jordan-Brans-Dicke theory. Phys. Rev. D. 2005;71:104025. doi: 10.1103/PhysRevD.71.104025. - DOI
    1. Adams FC. Stars in other universes: stellar structure with different fundamental constants. J. Cosmol. Astropart. Phys. 2008;2008(08):010. doi: 10.1088/1475-7516/2008/08/010. - DOI
    1. Adelberger EG. New tests of Einstein’s equivalence principle and Newton’s inverse-square law. Class. Quantum Grav. 2001;18:2397–2405. doi: 10.1088/0264-9381/18/13/302. - DOI
    1. Agrawal V, Barr SM, Donoghue JF, Seckel D. Anthropic considerations in multiple-domain theories and the scale of electroweak symmetry breaking. Phys. Rev. Lett. 1998;80:1822. doi: 10.1103/PhysRevLett.80.1822. - DOI

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