Primordial fluctuations

The two error terms refer to Yp and the regression slope respectively. In contrast to some earlier work, based on less homogeneous data sets and apparently affected by underlying absorption lines, notably in I Zw 18, this result, together with a similar one by Peimbert, Luridiana and Peimbert (2007), gives a primordial helium abundance in excellent agreement with the one predicted theoretically on the basis of the microwave background fluctuations and the lower estimates of deuterium abundance (see Fig. 4.3), a comparatively small value of about 2 for AT/AZ and no... 

There is considerable experimental evidence [9-15] for density fluctuations at very early times of crystallization before the full crystallographic features can be detected. What are the molecular origins of structural development in the primordial stage of polymer crystallization ... 

In the previous section we saw that temperature fluctuations on the sky are the solution to a linear differential equation relating the temperature to the underlying potential fluctuations or more specifically to the primordial potential fluctuations (as created by, say, inflation). Similarly, the mass fluctuations, S(r), are also linearly related to the primordial potential fluctuations. 

There were times on our planet when the barren dryness of uninhabited continents sharply contrasted with the densely populated sea. The continental lithosphere was then essentially represented by rock surfaces of different types. Sedimentary rocks were rare, if not absent. As rock materials became exposed to the subaerial environment at the Earth s surface, they encountered a whole range of environmental challenges such as temperature fluctuations, water, unbuffered cosmic and solar irradiation and atmospheric gases and solids instead of dissolved species. These influences resulted in rocks undergoing alterations in material properties leading to erosion and breakdown into ever-smaller particles and constituent minerals, formation of sandy sediments, and mineral soils (Ehrlich, 1996). Primordial terrestrial environments can therefore be visualized as a freshly exposed and only slightly physically pre-weathered rock surface. 

PBH formation is bound up with the primordial density fluctuations spectrum. Inflation produces a scale invariant spectrum the root mean square fluctuation e for an inhomogeneity just inside the horizon is M independent. When the propitious time (42) comes, a PBH can form only if the density contrast 5 = 5p/p at horizon scale is large enough the rule is that for equation of state p = wp, 5 must exceed w. Evidently, the fraction (5 of horizon-size volumes which actually collapse (the probability that the inhomogeneity makes a PBH), is M independent. 

It is clear from Fig. 16 that for a large range in r], a combination of ANv and e can be found so that the BBN-predicted abundances will lie within our adopted primordial abundance ranges. However, there are constraints on 77 and ANv from the CMB temperature fluctuation spectrum (see KSSW for details and further references). Although the CMB temperature fluctuation spectrum is insensitive to e, it will be modified by any changes in the universal expansion rate. While SBBN (ANv = 0) is consistent with the combined constraints from BBN and the CMB (see 5.5) for 7710 5.8 (Qb 2 0.021), values of ANv as large as ANv 6 are also allowed (KSSW). 

If further observational and associated theoretical work should confirm the current tension among the SBBN-predicted and observed primordial abundances of D, 4He, 7Li, what physics beyond the standard models of cosmology and particle physics has the potential to resolve the apparent conflicts Are those models which modify the early, radiation-dominated universe expansion rate consistent with observations of the CMB temperature fluctuation spectrum If neutrino degeneracy is invoked, is it consistent with the neutrino properties (masses and mixing angles) inferred from laboratory experiments as well as the solar and cosmic ray neutrino oscallation data ... 

Thus, a fit of 77 to observed primordial abundances not only probes the conditions in the early Universe at the time of nucleosynthesis hut can also reveal the curvature of the Universe, or at least the baryonic contribution to that curvature (Schramm and Turner 1998). Historically, primordial nucleosynthesis was the first tool for determining the geometry of the Universe. With the increased accuracy in the resolution of the angular multipole expansion of the CMBR temperature fluctuations dehvered hy WMAP, the total density of the Universe (and not just the baryonic one) can be determined independently now (see Sect. 12.2.1). 

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