Arthur Mezhlumian | Searcharxiv

arXiv2006

From the Big Bang Theory to the Theory of a Stationary Universe

We consider chaotic inflation in the theories with the effective potentials phi^n and e^{αϕ}. In such theories inflationary domains containing sufficiently large and homogeneous scalar field ϕpermanently produce new inflationary domains of a similar type. We show that under certain conditions this process of the self-reproduction of the Universe can be described by a stationary distribution of probability, which means that the fraction of the physical volume of the Universe in a state with given properties (with given values of fields, with a given density of matter, etc.) does not depend on time, both at the stage of inflation and after it. This represents a strong deviation of inflationary cosmology from the standard Big Bang paradigm. We compare our approach with other approaches to quantum cosmology, and illustrate some of the general conclusions mentioned above with the results of a computer simulation of stochastic processes in the inflationary Universe.

gr-qc↗

arXiv1996

Nonperturbative Amplifications of Inhomogeneities in a Self-Reproducing Universe

We investigate the distribution of energy density in a stationary self-reproducing inflationary universe. We show that the main fraction of volume of the universe in a state with a given density at any given moment of proper time t is concentrated near the centers of deep exponentially wide spherically symmetric wells in the density distribution. Since this statement is very surprising and counterintuitive, we perform our investigation by three different analytical methods to verify our conclusions, and then confirm our analytical results by computer simulations. If one assumes that we are typical observers living in the universe at a given moment of time, then our results may imply that we should live near the center of a deep and exponentially large void, which we will call infloid. Validity of this particular interpretation of our results is not quite clear since it depends on the as-yet unsolved problem of measure in quantum cosmology. Therefore at the moment we would prefer to consider our results simply as a demonstration of nontrivial properties of the hypersurface of a given time in the fractal self-reproducing universe, without making any far-reaching conclusions concerning the structure of our own part of the universe. Still we believe that our results may be of some importance since they demonstrate that nonperturbative effects in quantum cosmology, at least in principle, may have significant observational consequences, including an apparent violation of the Copernican principle.

gr-qc↗

arXiv1995

On Regularization Scheme Dependence of Predictions in Inflationary Cosmology

We show that there exists a large class of regularization schemes for probabilistic predictions in the theory of a self-reproducing inflationary univere, all of which eliminate the apparent dependence on the time reparametrization. However, all these schemes lead to different answers for relative probabilities of finding various types of post-inflationary universes. Besides, all these schemes fail to be reparametrization invariant beyond the range of the inflaton field close to end of inflation boundary. Therefore, we argue that at the current level of understanding, the simple regularization schemes associated with cutoffs at equal time hypersurfaces are as good as the recently proposed more complicated procedures which try to fix the time-reparametrization dependence.

gr-qc↗

arXiv1995

Inflation with $Ω\not = 1$

We discuss various models of inflationary universe with $Ω\not = 1$. A homogeneous universe with $Ω> 1$ may appear due to creation of the universe "from nothing" in the theories where the effective potential becomes very steep at large $ϕ$, or in the theories where the inflaton field $ϕ$ nonminimally couples to gravity. Inflation with $Ω< 1$ generally requires intermediate first order phase transition with the bubble formation, and with a second stage of inflation inside the bubble. It is possible to realize this scenario in the context of a theory of one scalar field, but typically it requires artificially bent effective potentials and/or nonminimal kinetic terms. It is much easier to obtain an open universe in the models involving two scalar fields. However, these models have their own specific problems. We propose three different models of this type which can describe an open homogeneous inflationary universe.

astro-ph↗

arXiv1994

Do We Live in the Center of the World?

We investigate the distribution of energy density in a stationary self-reproducing inflationary universe. We show that the main fraction of volume of the universe in a state with a given density $ρ$ at any given moment of time $t$ in synchronous coordinates is concentrated near the centers of deep exponentially wide spherically symmetric holes in the density distribution. A possible interpretation of this result is that a typical observer should see himself living in the center of the world. Validity of this interpretation depends on the choice of measure in quantum cosmology. Our investigation suggests that unexpected (from the point of view of inflation) observational data, such as possible local deviations from $Ω= 1$, or possible dependence of the Hubble constant on the length scale, may tell us something important about quantum cosmology and particle physics at nearly Planckian densities.

hep-th↗

arXiv1994

Stationary Universe Model: Inputs and Outputs

This is the text of a talk given at the Rome Conference "The Birth of the Universe and Fundemental Physics", May, 1994. We present the recent progress achieved in collaboration with A.Linde and D.Linde towards understanding the true nature of the global spatial structure of the universe as well as the most general stationary characteristics of its time-dependent state with eternally growing total volume.

astro-ph↗

arXiv1993

Stationary Universe

If the Universe contains at least one inflationary domain with a sufficiently large and homogeneous scalar field, then this domain permanently produces new inflationary domains of all possible types. We show that under certain conditions this process of the self-reproduction of the Universe can be described by a stationary distribution of probability, which means that the fraction of the physical volume of the Universe in a state with given properties (with given values of fields, with a given density of matter, etc.) does not depend on time. This represents a strong deviation of inflationary cosmology from the standard Big Bang paradigm.

gr-qc↗

arXiv1993

Towards the Theory of Stationary Universe

This talk presents some progress achieved in collaboration with A.Linde and D.Linde towards understanding the true nature of the global spatial structure of the Universe as well as the most general stationary characteristics of its time-dependent state with eternally growing total volume.

gr-qc↗