The Quest for Fine-Scale Anisotropy in the Relict Radiation

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Abstract
Up to Symposium Session IV, the observed properties of the large scale structure of the Universe have been discussed in terms of studies based on the spatial distribution of galaxies with redshift less than one; studies which indicate clustering on characteristic scales up to ~20 Mpc or equivalently ~1015M⊙. Such a survey is rather local in scope compared to what in principle could be inferred from the measurement of temperature fluctuations in the relict radiation surviving from Z ≃ 1000 as the fossil imprint of “primordial” density fluctuations on scales up to the horizon at the epoch of decoupling, M ≃ 1019M⊙. However, the investigation of structure over a still-larger sample volume and scales greater than 1015M⊙ is not a possibility which I wish to stress in this paper. Rather, given our present state of ignorance about the formation of structure, perhaps a more fruitful first approach would be to examine small angular scales in the relict radiation for insight into the evolution of density perturbations by a careful comparison between the observationally inferred “initial” spectrum of mass inhomogeneities present back at the epoch of decoupling, and the mass spectrum of clustering which characterizes the present Universe.