Fluctuations Threshold Classical Cosmology Physical by Harrison E R (1 results)
More imagesPublished by American Physical Society, Physical Review D, Particles and Fields, third series, volume 1 #10, 15 May 1970, pp 2726-2730, in the full issue of pp 2721-2984. 1970
- Softcover
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Soft cover. Condition: Very Good. Original wrappers. Owner's name at top right corner. There is a little bit of the top spine cover missing (about 25mm). VG/F copy nevertheless. $450 Edward R. "Ted" Harrison (1919 2007) was a British astronomer and cosmologist, noted for his work about the increase of fluctuations in the expandi…ng universe, for his explanation of Olbers' Paradox, and for his books on cosmology for lay readers.The work of Harrison and of Soviet physicist Yakov Borisovich Zel'dovich [the Harrison paper being offered here]on structure formation from primordial density perturbations in the cosmic plasma has led to the general use of the term Harrison-Zel'dovich spectrum for primordial random fluctuations characterised by a scale-invariant power spectrum."--Wikipedia entry for Harrison [++] "The alternative picture involves the inflationary universe. Inflation relies on the existence of a quantum scalar field whose vacuum energy drives the Universe into an accelerated expansion, ironing out any wrinkles and simultaneously decreasing the curvature of spacetime virtually to zero. But the scalar field also produces small fluctuations because of quantum fluctuations in it, essentially arising from Heisenberg's uncertainty principle (see quantum mechanics). The initial fluctuations arising from inflationary models are much simpler than in the case of topological defects: the quantum fluctuations are small. so that methods from perturbation theory can be used. They are also statistically simple: the density field resulting from quantum fluctuations is of the simplest form known in probability theory - the form which is known as a Gaussian random field. The properties of such a field are described completely by the power spectrum of the fluctuations. In inflationary models the appropriate power spectrum is of a form known as the scale-invariant spectrum, which was derived (for an entirely different purpose) in the 1970s independently by Edward Harrison and by Yakov Zel'dovich.[the Harrison paper offered for sale here].This scale-invariant spectrum is particularly important because we know from very simple arguments that the Universe has to possess fluctuations that are nearly scale-invariant. The term `scale-invariant' means that fluctuations in the metric (the equivalent in Newtonian language to fluctuations in the gravitational potential) have the same amplitude on all scales."--"Primordial Density Fluctuations", adapted from P. Coles, The Routledge Critical Dictionary of the New Cosmology, Routledge Inc., New York., 1999. [++] The Zel'dovich part of this is found in Zel'dovich, Ya.B., "A hypothesis unifying the structure and entropy of the Universe', Monthly Notices of the Royal Astronomical Society, 1972, 160, 1p I am not offering it here. [++] "It was Harrison and Zel dovich who originally suggested in the 1970s that ns should be close to one The ability to reproduce the observed matter power spectrum P(k) to high accuracy is often considered as a triumph of inflation. In this work, we explore an alternative explanation for the power spectrum based on nonperturbative quantum field-theoretical methods applied to Einstein s gravity, instead of ones based on inflation models. In particular, the power spectral index, which governs the slope on the P(k) graph, can be related to critical scaling exponents derived from the Wilson renormalization group analysis. We find that the derived value fits favorably with the Sloan Digital Sky Survey telescope data. We then make use of the transfer functions, based only on the Boltzmann equations, which describe states out of equilibrium, and Einstein s general relativity, to extrapolate the power spectrum to the Cosmic Microwave Background (CMB) scales and uses the transfer function to extrapolate it to the galaxy regime."--See: Herbert W. Hamber and Lu Heng Sunny Yu: "Gravitational Fluctuations as an Alternative to Inflation", Universe 2019, 5(1), 31. [++].
