Volume 88, Number 5, December 2009
Article Number 59002
Number of page(s) 6
Section Geophysics, Astronomy and Astrophysics
Published online 16 December 2009
EPL, 88 (2009) 59002
DOI: 10.1209/0295-5075/88/59002

About some possible empirical evidences in favor of a cosmological time variation of the speed of light

Y.-H. Sanejouand

Laboratoire U3B, UMR 6204 of CNRS, Faculté des Sciences - 2 rue de la Houssinière, Nantes, France, EU

received 4 October 2009; accepted in final form 16 November 2009; published December 2009
published online 16 December 2009

Possible empirical evidences in favor of the hypothesis that the speed of light decreases by a few centimeters per second each year are examined. Lunar laser ranging data are found to be consistent with this hypothesis, which also provides a straightforward explanation for the so-called Pioneer anomaly, that is, a time-dependent blue-shift observed when analyzing radio tracking data from distant spacecrafts, as well as an alternative explanation for both the apparent time-dilation of remote events and the apparent acceleration of the Universe. The main argument against this hypothesis, namely, the constancy of fine-structure and Rydberg constants, is discussed. Both of them being combinations of several physical constants, their constancy implies that, if the speed of light is indeed time-dependent, then at least two other “fundamental constants” have to vary as well. This puts severe constraints on the development of any future varying–speed-of-light theory.

95.55.Pe - Lunar, planetary, and deep-space probes.
98.80.Es - Observational cosmology (including Hubble constant, distance scale, cosmological constant, early Universe, etc.).
06.20.-f - Metrology.

© EPLA 2009