A franco-american quintet of cosmologists conducted by Jean-Pierre Luminet, from Paris Observatory (LUTH), has proposed an original explanation to account for a surprising detail observed in the Cosmic Microwave Background (CMB) recently mapped by the NASA satellite WMAP. According to the team, who published their study in the 9 october 2003 issue of "Nature", an intriguing discrepancy in the background luminous texture of the Universe can indeed be explained by a very specific global shape of space (its "topology"). The Universe could be wrapped around, a little bit like a "soccer ball", the volume of which would represent only 80% of the observable Universe! According to the leading cosmologist George Ellis, from Cape Town University (South Africa), who comments this letter in the "News & Views" of the same issue: "If confirmed, it is a major discovery about the nature of the Universe".
Cosmologists study the topology of space by analyzing in great details the temperature fluctuations of the fossil Cosmic Microwave Background [note a]. The standard cosmological model describes the Universe as a flat infinite space in eternal, accelerated expansion under the effect of a repulsive "dark energy". The data collected by the NASA satellite WMAP (Wilkinson Microwave Anisotropy Probe), which has recently produced a high resolution map of the CMB, allowed to check the validity of such an expansion model. Temperature fluctuations on small and mean scales (i.e. concerning regions of the sky of relatively modest size) are compatible with the infinite flat space hypothesis. However, on angular scales larger than 60°, the observed correlations are notably weaker that those predicted by the standard model. Thus the scientists are looking for an alternative.
Jean-Pierre Luminet | alfa
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