Addemdum to: ''The Mathematical Structure of Quantum Superspace as a Consequence of Time Asymmetry''

In this paper we improve the results of sec. VI of paper [M. Castagnino, Phys. Rev. D 57, 750 (1998)] by considering that the main source of entropy production are the photospheres of the stars

The arrow of time: from universe time-asymmetry to local irreversible processes

In several previous papers we have argued for a global and non-entropic approach to the problem of the arrow of time, according to which the ''arrow'' is only a metaphorical way of expressing the geometrical time-asymmetry of the universe. We have also shown that, under definite conditions, this global time-asymmetry can be transferred to local contexts as an energy flow that points to the same temporal direction all over the spacetime. The aim of this paper is to complete the global and non-entropic program by showing that our approach is able to account for irreversible local phenomena, which have been traditionally considered as the physical origin of the arrow of time.Comment: 48 pages, 8 figures, revtex4. Accepted for publication in Foundations of Physic

Functional Approach to Quantum Decoherence and the Classical Final Limit

For a wide set of quantum systems it is demonstrated that the quantum regime can be considered as the transient phase while the final classical statistical regime is a permanent state. A basis where exact matrix decoherence appears for these final states is found. The relation with the decoherence of histories formalism is studied. A set of final intrinsically consistent histories is found.Comment: 20 pages. Phys. Rev A in press 200

Thermal Conditions for Scalar Bosons in a Curved Space Time

The conditions that allow us to consider the vacuum expectation value of the energy-momentum tensor as a statistical average, at some particular temperature, are given. When the mean value of created particles is stationary, a planckian distribution for the field modes is obtained. In the massless approximation, the temperature dependence is as that corresponding to a radiation dominated Friedmann-like model.Comment: 14 pages (TeX manuscript

Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier

We investigate the resonant states for the parabolic potential barrier known also as inverted or reversed oscillator. They correspond to the poles of meromorphic continuation of the resolvent operator to the complex energy plane. As a byproduct we establish an interesting relation between parabolic cylinder functions (representing energy eigenfunctions of our system) and a class of Gel'fand distributions used in our recent paper.Comment: 14 page

Thermodynamic Limit and Decoherence: Rigorous Results

Time evolution operator in quantum mechanics can be changed into a statistical operator by a Wick rotation. This strict relation between statistical mechanics and quantum evolution can reveal deep results when the thermodynamic limit is considered. These results translate in a set of theorems proving that these effects can be effectively at work producing an emerging classical world without recurring to any external entity that in some cases cannot be properly defined. In a many-body system has been recently shown that Gaussian decay of the coherence is the rule with a duration of recurrence more and more small as the number of particles increases. This effect has been observed experimentally. More generally, a theorem about coherence of bulk matter can be proved. All this takes us to the conclusion that a well definite boundary for the quantum to classical world does exist and that can be drawn by the thermodynamic limit, extending in this way the deep link between statistical mechanics and quantum evolution to a high degree.Comment: 5 pages, no figures. Contribution to proceedings of DICE 2006 (Piombino, Italy, September 11-15, 2006

Un modelo de partícula escalar: hipótesis mínimas

La teoría cuántica de campos en un espacio-tiempo curvo predice la creación de partículas a expensas del campo gravitatorio que, introducido a través de una métrica clásica, interactúa con los campos de materia y radiación cuantificados.Asociación Argentina de Astronomí

Decoherence time in self-induced decoherence

A general method for obtaining the decoherence time in self-induced decoherence is presented. In particular, it is shown that such a time can be computed from the poles of the resolvent or of the initial conditions in the complex extension of the Hamiltonian's spectrum. Several decoherence times are estimated: $10^{-13}-$ $10^{-15}s$ for microscopic systems, and $10^{-37}-10^{-39}s$ for macroscopic bodies. For the particular case of a thermal bath, our results agree with those obtained by the einselection (environment-induced decoherence) approach.Comment: 11 page

Scalar particles creation rate in an expanding universe

Quantum field theory in curved space-time, where the gravitational field is treated as a classical solution of Einstein field equations and matter and radiation fields are quantized in that background, predicts the creation of particles in non-static situations, such as in an expanding universe (see refs. 1, 2 & 3 for recent reviews).Asociación Argentina de Astronomí

Implicancias cosmológicas de un modelo de partícula escalar

Se muestra la posibilidad de construir un modelo de partículas de spin 0 en un universo espacialmente plano en expansión, hasta primer orden en potencias del tensor de curvatura. La arbitrariedad en la elección del núcleo G₁, generalización del Δ₁ que en el espacio-tiempo plano permite efectuar la descomposición invariante de un campo escalar en partes de frecuencia positiva y negativa, se elimina pidiendo que los datos de Cauchy sobre cada superficie espacial del universo satisfagan el límite minkowskiano. El G₁ determinado de esta manera será una función distinta sobre cada superficie de Cauchy lo que implica la mezcla de las funciones de onda de frecuencia positiva y negativa con el transcurso del tiempo, dando lugar al fenómeno de creación de partículas. Pasa a la generalidad del modelo, los parámetros introducidos quedan todos determinados, excepto uno que justamente es el de mayor interés físico. Esta arbitrariedad permite considerar dos aplicaciones cosmológicas que lo determinarían. Por un lado, es posible que el espectro de energía de las partículas creadas sea convergente, lo que permite re-introducir esta materia como fuente en las ecuaciones de Einstein y estudiar sus efectos sobre la evolución del universo. Por otro lado, el parámetro arbitrario puede quedar determinado suponiendo un origen cosmológico para la radiación cósmica de fondo, ya que aparece en un término de la expresión de la energía cuya forma coincide con los datos experimentales para los rayos X y γ difusos.Asociación Argentina de Astronomí