2,532 research outputs found
Pure States, Mixed States and Hawking Problem in Generalized Quantum Mechanics
This paper is the continuation of a study into the information paradox
problem started by the author in his earlier works. As previously, the key
instrument is a deformed density matrix in quantum mechanics of the early
universe. It is assumed that the latter represents quantum mechanics with
fundamental length. It is demonstrated that the obtained results agree well
with the canonical viewpoint that in the processes involving black holes pure
states go to the mixed ones in the assumption that all measurements are
performed by the observer in a well-known quantum mechanics. Also it is shown
that high entropy for Planck remnants of black holes appearing in the
assumption of the Generalized Uncertainty Relations may be explained within the
scope of the density matrix entropy introduced by the author previously. It is
noted that the suggested paradigm is consistent with the Holographic Principle.
Because of this, a conjecture is made about the possibility for obtaining the
Generalized Uncertainty Relations from the covariant entropy bound at high
energies in the same way as R. Bousso has derived Heisenberg uncertainty
principle for the flat space.Comment: 12 pages,no figures,some corrections,new reference
The Universe as a Nonuniform Lattice in the Finite-Dimensional Hypercube II.Simple Cases of Symmetry Breakdown and Restoration
This paper continues a study of field theories specified for the nonuniform
lattice in the finite-dimensional hypercube with the use of the earlier
described deformation parameters. The paper is devoted to spontaneous breakdown
and restoration of symmetry in simple quantum-field theories with scalar
fields. It is demonstrated that an appropriate deformation opens up new
possibilities for symmetry breakdown and restoration. To illustrate, at low
energies it offers high-accuracy reproducibility of the same results as with a
nondeformed theory. In case of transition from low to higher energies and vice
versa it gives description for new types of symmetry breakdown and restoration
depending on the rate of the deformation parameter variation in time, and
indicates the critical points of the previously described lattice associated
with a symmetry restoration. Besides, such a deformation enables one to find
important constraints on the initial model parameters having an explicit
physical meaning.Comment: 9 pages,Revte
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#Bigbirds never die: Understanding social dynamics of emergent hashtag
We examine the growth, survival, and context of 256 novel hashtags during the 2012 U.S. presidential debates. Our analysis reveals the trajectories of hashtag use fall into two distinct classes: “winners” that emerge more quickly and are sustained for longer periods of time than other “also-rans” hashtags. We propose a “conversational vibrancy” framework to capture dynamics of hashtags based on their topicality, interactivity, diversity, and prominence. Statistical analyses of the growth and persistence of hashtags reveal novel relationships between features of this framework and the relative success of hashtags. Specifically, retweets always contribute to faster hashtag adoption, replies extend the life of “winners” while having no effect on “also-rans.” This is the first study on the lifecycle of hashtag adoption and use in response to purely exogenous shocks. We draw on theories of uses and gratification, organizational ecology, and language evolution to discuss these findings and their implications for understanding social influence and collective action in social media more generally
Quantum Mechanics at Planck's scale and Density Matrix
In this paper Quantum Mechanics with Fundamental Length is chosen as Quantum
Mechanics at Planck's scale. This is possible due to the presence in the theory
of General Uncertainty Relations. Here Quantum Mechanics with Fundamental
Length is obtained as a deformation of Quantum Mechanics. The distinguishing
feature of the proposed approach in comparison with previous ones, lies on the
fact that here density matrix subjects to deformation whereas so far
commutators have been deformed. The density matrix obtained by deformation of
quantum-mechanical density one is named throughout this paper density
pro-matrix. Within our approach two main features of Quantum Mechanics are
conserved: the probabilistic interpretation of the theory and the well-known
measuring procedure corresponding to that interpretation. The proposed approach
allows to describe dynamics. In particular, the explicit form of deformed
Liouville's equation and the deformed Shr\"odinger's picture are given. Some
implications of obtained results are discussed. In particular, the problem of
singularity, the hypothesis of cosmic censorship, a possible improvement of the
definition of statistical entropy and the problem of information loss in black
holes are considered. It is shown that obtained results allow to deduce in a
simple and natural way the Bekenstein-Hawking's formula for black hole entropy
in semiclassical approximation.Comment: 18 pages,Latex,new reference
Mechanism of Modifying Ballistic Properties of Propellant Formulations by Fast-Burning Inclusions
The combustion characteristics of binary compositions of fast-burning energetic materials (FBEM) with main composite propellant components like ammonium perchlorate (AP) and polymeric binders have been studied in a constant pressure bomb, and combustion mechanism has been proposed. Combustion behaviour of composite propellants containing granulated FBEM of different particle sizes has been investigated. FBEM additives as high as 40 per cent of fine particle size to a composite propellant have not been shown to influence markedly the burning rate, whereas incorporation of FBEM grains of 500 micrometer particle size allows not only a considerable increase in the burning rate but also modifies the burning rate-pressure dependence. A mechanism of combustion of propellant compositions containing FBEM grains has been evolved that allows criteria for FBEM performance and combustion stability
Superaging correlation function and ergodicity breaking for Brownian motion in logarithmic potentials
We consider an overdamped Brownian particle moving in a confining
asymptotically logarithmic potential, which supports a normalized Boltzmann
equilibrium density. We derive analytical expressions for the two-time
correlation function and the fluctuations of the time-averaged position of the
particle for large but finite times. We characterize the occurrence of aging
and nonergodic behavior as a function of the depth of the potential, and
support our predictions with extensive Langevin simulations. While the
Boltzmann measure is used to obtain stationary correlation functions, we show
how the non-normalizable infinite covariant density is related to the
super-aging behavior.Comment: 16 pages, 6 figure
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