Cosmological potential

The critical density is traditionally dehned as that density which separates the closed (finite) universe from the open (infinite) universe in the simplest model available, i.e. in a universe without cosmological constant or quintessence. It corresponds to a universe with zero total energy, where the kinetic energy due to expansion is exactly balanced by gravitational potential energy. The value of the critical density is 10 gcm, which amounts to very httle when compared to a chunk of iron ... 

After reviewing these observational results, I will argue that either alone presents modern cosmology with a potentially fatal crisis—beyond the ability of... 

Initially, these claims raised quite a lot of interest—but it soon became apparent that the claimed effects were deeply problematical from the point of view of prevailing cosmology and, very conveniently, that Tifft s own statistical methods were very far from being robust. This latter fact made it very easy for the community to ignore a potentially very difficult problem for the status quo. 

Of these possibilities, the constant potential universe is the one that suits the needs of a realistic cosmology, and this possibility is discussed in detail in the following sections. 

Huber C, Wachtershauser G (2006) a-hydroxy and a-amino acids under possible Hadean, volcanic origin-of-life conditions. Science 314 630-632 Huber H, Stetter KO (1998) Hyperthermophiles and their possible potential in biotechnology. J Biotechnol 64 39-52 Hurtgen MT, Arthur MA, Halverson GP (2005) Neoproterozoic sulfur isotopes, the evolution of microbial sulfur species, and the burial efficiency of sulfide as sedimentary pyrite. Geology 33 41-44 Husain V, Winkler O (2007) Semiclassical states for quantum cosmology. Phys Rev D 75 024014... 

Before continuing the study of the dynamics of the inflationary phase, let us focus on one specific example of inflationary scenario chaotic inflation. Historically, this was not the first model that was proposed but we think it was the first to provide a satisfactory scenario. The main difficulty with inflation is to have the slow roll conditions to be satisfied at some epoch. Indeed, as we saw, one need to put the field away from the minimum of its potential for the inflaton to behave like a cosmological constant. The first inflationary model ( Guth 1981) supposed a potential like that of Eq. (7.28) where the field slowly moved away from its minimum because of a phase transition. However, this led to a number of difficulties, see for example Ref. (Liddle Lyth). Fortunately, it was soon realized that it was not necessary to have a time dependent potential for inflation to proceed. Linde (Linde 1985) noticed that inflation could start as soon as the Universe would exit the Planck era. The idea was that it is reasonable to suppose that at the end of the Planck era (when p > ), no large-scale correlation could be expected in the scalar field, so that one could expect very irregular (hence, chaotic) initial condition with... 

As we have seen during the course on inflation, a scalar field can behave as a cosmological constant when its kinetic term becomes negligible in front of its potential term. However, the features of the scalar field we are interested in differ significantly from an inflationary scalar field in the former case, we want a field that is negligible at early times and which dominates afterwards, whereas in the latter case, it is the contrary. Historically, the first scalar field dark energy model was aimed to address the possibility to have some components with a constant equation of state parameter w other than 0 (matter), 1/3 (radiation), —1/3 (curvature) and —1 (cosmological constant) (Ratra Peebles 1988). 

A second relation involving a can in principle be derived when we know the current value of the dark energy equation of state parameter wbe- Indeed, since the potential does not possess a local minimum, the field never stops, so that it never behaves exactly as a cosmological constant. Moreover, even if its equation of state parameter w decays (without ever reaching) toward —1, the rate at which this transition occurs depends on the steepness of the potential the steeper the potential, the slowest w goes toward —1. In particular, one finds, at the epoch Qq 0.7,... 

Evolution is another potential effect, which could mimic a cosmological signal. This is much harder to control. For reasonable predictions of how... 

And the source term of the deflexion is the gravitational potential, , which in a cosmological context is given by a slightly modified Poisson equation,... 

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 ... 

Other anthropic explanations for the value of the cosmological constant and the why now problem have been suggested in the context of maximally extended (N = 8) supergravity (Kallosh and Linde, 2003 Linde, 2003). In particular, the former authors found that the universe can have a suffciently long lifetime only if the scalar field satisfies initially (j) Mp and if the value of the potential V(0), which plays the role of the cosmological constant, does not exceed the critical density po 10 "/Wj,. 

A planet in orbit therefore looses energy, and like a classical orbiting electron (section 3.4.2), spirals in towards the nucleus of the system. In the case of an atom this is prevented by the quantum potential and there is no reason why a cosmological quantum effect could not be responsible for the stabilization of satellite orbits. In fact, there is the evidence of planets and moons in the solar system on orbits characterized by integers, as discussed in section 5.3.1. The cosmological term. A, which Einstein included in the gravitational field equations (6.4) describes exactly such an effect. 

Only at w = c the wavelength, although indeterminate, is finite and the resulting photon has energy E = hi/. For r c, A —> oo. Thus, an infon is a photon whose wavelength has been stretched to infinity, readily identified with the quantum potential, and providing a simple interpretation of cosmological redshifts. 

The author himself regards SSCM in its present form as natural philosophy rather than proven science, but its potential to elucidate cosmic phenomena is enormous. Cosmological redshift is a relevant example. As observed it is a galactic-scale phenomenon, which should correlate with an atomic-scale counterpart. The proposed chemical redshift (5.1.2) is the most likely candidate for this role. The theory predicts an enormous number of small black holes, which, re-interpreted as penetrating a vacuum interface, may lead to the recognition of new sources of astronomical luminosity. 

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