Towards a formal description of the collapse approach to the inflationary origin of the seeds of cosmic structure

Abstract

Inflation plays a central role in our current understanding of the universe. According to the standard viewpoint, the homogeneous and isotropic mode of the inflaton field drove an early phase of nearly exponential expansion of the universe, while the quantum fluctuations (uncertainties) of the other modes gave rise to the seeds of cosmic structure. However, if we accept that the accelerated expansion led the universe into an essentially homogeneous and isotropic space-time, with the state of all the matter fields in their vacuum (except for the zero mode of the inflaton field), we can not escape the conclusion that the state of the universe as a whole would remain always homogeneous and isotropic. It was recently proposed in [A. Perez, H. Sahlmann and D.Sudarsky, "On the quantum origin of the seeds of cosmic structure," Class. Quant. Grav. 23, -2354 (2006)] that a collapse (representing physics beyond the established paradigm, and presumably associated with a quantum-gravity effectà la Penrose) of the state function of the inflaton field might be the missing element, and thus would be responsible for the emergence of the primordial inhomogeneities. Here we will discuss a formalism that relies strongly on quantum field theory on curved space-times, and within which we can implement a detailed description of such a process. The picture that emerges clarifies many aspects of the problem, and is conceptually quite transparent. Nonetheless, we will find that the results lead us to argue that the resulting picture is not fully compatible with a purely geometric description of space-time. * Electronic address: alberto.diez@fisica.ugto.mx † Electronic address: sudarsky@nucleares.unam.mx 2317

Quantum origin of the primordial fluctuation spectrum and its statistics

“…[13]. In that work, it was found the collapse of a mode with comoving wave vector k 0 must be tied with the modification of the state of the field in the higher harmonics of that mode.…”

Inflation including collapse of the wave function: the quasi-de Sitter case

“…The full formalism has been developed in Ref. [5] and we invite the reader to consult such a reference. We also should mention that we are not advocating that semiclassical gravity must be regarded as a fundamental theory; we are using it as an appropriate approximation given the energy scales of the inflationary universe (∼10 16 GeV), i.e.…”

Nonparadoxical loss of information in black hole evaporation in a quantum collapse model

“…More precise characterizations, both in the treatment of fluids and of gravitation, can be expected to involve higher order and more complicated terms, and, of course eventually, as the natural scale of the more fundamental and underlying theory is approached, one would expect the complete breakdown of the effective description. Some initial steps in the exploration of the formal adaptation of this approach to the use of semi-classical gravity in a cosmological context have been considered in [44]. We should also note the work [45] in which the general arguments against semi-classical gravity were critically considered, concluding that they are not as robust as it might have seemed initially.…”