5,938 research outputs found

    Comment on "Why quantum mechanics cannot be formulated as a Markov process"

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    In the paper with the above title, D. T. Gillespie [Phys. Rev. A 49, 1607, (1994)] claims that the theory of Markov stochastic processes cannot provide an adequate mathematical framework for quantum mechanics. In conjunction with the specific quantum dynamics considered there, we give a general analysis of the associated dichotomic jump processes. If we assume that Gillespie's "measurement probabilities" \it are \rm the transition probabilities of a stochastic process, then the process must have an invariant (time independent) probability measure. Alternatively, if we demand the probability measure of the process to follow the quantally implemented (via the Born statistical postulate) evolution, then we arrive at the jump process which \it can \rm be interpreted as a Markov process if restricted to a suitable duration time. However, there is no corresponding Markov process consistent with the Z2Z_2 event space assumption, if we require its existence for all times t∈R+t\in R_+.Comment: Latex file, resubm. to Phys. Rev.

    Weak nuclear forces cause the strong nuclear force

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    We determine the strength of the weak nuclear force which holds the lattices of the elementary particles together. We also determine the strength of the strong nuclear force which emanates from the sides of the nuclear lattices. The strong force is the sum of the unsaturated weak forces at the surface of the nuclear lattices. The strong force is then about ten to the power of 6 times stronger than the weak force between two lattice points.Comment: 12 pages, 1 figur

    Quantum Information and Wave function Collapse

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    Inofrmation-theoretical restrictions on information transferred in the measurement of object S by information system O are studied. It is shown that such constraints, induced by Heisenberg commutation relations, result in the loss of information about the purity of S state. Consequently, it becomes impossible for O to discriminate pure and mixed S states. In individual events this effect is manifested by the stochastic outcomes of pure S state measurement, i.e. the collapse of pure S state.Comment: 8 pages, talk given on Simposium 'Frontiers of fundamental Physics', Udine, Italy, January 2008, to appear in Proceeding

    Exact Ground State and Finite Size Scaling in a Supersymmetric Lattice Model

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    We study a model of strongly correlated fermions in one dimension with extended N=2 supersymmetry. The model is related to the spin S=1/2S=1/2 XXZ Heisenberg chain at anisotropy Δ=−1/2\Delta=-1/2 with a real magnetic field on the boundary. We exploit the combinatorial properties of the ground state to determine its exact wave function on finite lattices with up to 30 sites. We compute several correlation functions of the fermionic and spin fields. We discuss the continuum limit by constructing lattice observables with well defined finite size scaling behavior. For the fermionic model with periodic boundary conditions we give the emptiness formation probability in closed form.Comment: 4 pages, 4 eps figure

    Hidden-variable theory versus Copenhagen quantum mechanics

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    The main assumptions the Copenhagen quantum mechanics has been based on will be summarized and the known (not yet decided) contradiction between Einstein and Bohr will be newly analyzed. The given assumptions have been represented basically by time-dependent Schroedinger equation, to which some further assumptions have been added. Some critical comments have been raised against the given mathematical model structure by Pauli (1933) and by Susskind and Glogover (1964). They may be removed if only the Schroedinger equation is conserved and the additional assumptions are abandoned, as shown recently. It seems to be in contradiction to the numerous declarations that the Copenhagen model has been approved by experimental results. However, in the most of these experiments only the agreement with the mere Schroedinger equation has been tested. All mentioned assumptions have been tested practically only in the EPR experiment (measurement of coincidence light transmission through two polarizers) proposed originally by Einstein (1935). Also these experimental results have been interpreted as supporting the Copenhagen alternative, which has not been, however, true. In fact the microscopic world may be described correspondingly only with the help of the hidden-variable theory that is represented by the Schroedinger equation without mentioned additional assumptions, which has the consequence that the earlier interpretation gap between microscopic and macroscopic worlds has been removed. The only difference concerns the existence of discrete states. The possibilities of the human reason of getting to know the nature will be also shortly discussed in the beginning of this contribution.Comment: 10 pages, 2 figures; v2: local refinements and improvements of the tex

    The Speed of Light and the Hubble Parameter: The Mass-Boom Effect

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    We prove here that Newtons universal gravitation and momentum conservation laws together reproduce Weinbergs relation. It is shown that the Hubble parameter H must be built in this relation, or equivalently the age of the Universe t. Using a wave-to-particle interaction technique we then prove that the speed of light c decreases with cosmological time, and that c is proportional to the Hubble parameter H. We see the expansion of the Universe as a local effect due to the LAB value of the speed of light co taken as constant. We present a generalized red shift law and find a predicted acceleration for photons that agrees well with the result from Pioneer 10/11 anomalous acceleration. We finally present a cosmological model coherent with the above results that we call the Mass-Boom. It has a linear increase of mass m with time as a result of the speed of light c linear decrease with time, and the conservation of momentum mc. We obtain the baryonic mass parameter equal to the curvature parameter, omega m = omega k, so that the model is of the type of the Einstein static, closed, finite, spherical, unlimited, with zero cosmological constant. This model is the cosmological view as seen by photons, neutrinos, tachyons etc. in contrast with the local view, the LAB reference. Neither dark matter nor dark energy is required by this model. With an initial constant speed of light during a short time we get inflation (an exponential expansion). This converts, during the inflation time, the Plancks fluctuation length of 10-33 cm to the present size of the Universe (about 1028 cm, constant from then on). Thereafter the Mass-Boom takes care to bring the initial values of the Universe (about 1015 gr) to the value at the present time of about 1055 gr.Comment: 15 pages, presented at the 9th Symposium on "Frontiers of Fundamental Physics", 7-9 Jan. 2008, University of Udine, Italy. Changed content

    Soil contribution on the structural identification of a historical masonry bell-tower: simplified vs advanced numerical models

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    In the last decade, structural identification techniques through dynamic in situ tests have been widely used to investigate the global dynamic behavior of ordinary buildings and built cultural heritage. The choice of proper boundary conditions at the base of the structure, however, is still a critical point in the development of sound numerical models able to reproduce building dynamic response reliably. The contribution of the foundation soil should be ascertained and, if necessary, properly modelled. The paper tries to shed light on the issue of soil-structure-interaction on the structural identification of masonry towers, with reference to the case study of the bell tower of Santa Sofia Church in Benevento (Italy). The experimental results of the dynamic identification, i.e. frequencies and modal shapes, have been interpreted and employed to calibrate both simplified and advanced numerical models of the soil-foundation-tower system. In the first case, soil compliance is represented by a set of springs attached at the base of the tower, which has been modelled as a 1D system. In the second case, a 3D finite element model comprehensive of the tower, the soil and the foundation structure has been developed. Pros and cons of the two numerical approaches on the structural identification process are highlighted and discussed.The authors thank Prof. Maria Rosaria Pecce for her precious support and suggestions. This research activity was carried out within the framework of the PON Research and Innovation 2014–2020, Axis I-Investments in Human Capital, MIUR notice AIM-“International Attraction and Mobility”- Line 1, Project: AIM 1823125-3 – Cultural Heritage. Part of the work has been developed in the framework of the 2019-2021 Reluis-DPC research program funded by the Italian Civil Protection Department, as a contribution to the geotechnical Work Package Soil-Foundation-Structure Interaction (Task 16.3)

    A novel background reduction strategy for high level triggers and processing in gamma-ray Cherenkov detectors

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    Gamma ray astronomy is now at the leading edge for studies related both to fundamental physics and astrophysics. The sensitivity of gamma detectors is limited by the huge amount of background, constituted by hadronic cosmic rays (typically two to three orders of magnitude more than the signal) and by the accidental background in the detectors. By using the information on the temporal evolution of the Cherenkov light, the background can be reduced. We will present here the results obtained within the MAGIC experiment using a new technique for the reduction of the background. Particle showers produced by gamma rays show a different temporal distribution with respect to showers produced by hadrons; the background due to accidental counts shows no dependence on time. Such novel strategy can increase the sensitivity of present instruments.Comment: 4 pages, 3 figures, Proc. of the 9th Int. Syposium "Frontiers of Fundamental and Computational Physics" (FFP9), (AIP, Melville, New York, 2008, in press

    Biological Principles in Self-Organization of Young Brain - Viewed from Kohonen Model

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    Variants of the Kohonen model are proposed to study biological principles of self-organization in a model of young brain. We suggest a function to measure aquired knowledge and use it to auto-adapt the topology of neuronal connectivity, yielding substantial organizational improvement relative to the standard model. In the early phase of organization with most intense learning, we observe that neural connectivity is of Small World type, which is very efficient to organize neurons in response to stimuli. In analogy to human brain where pruning of neural connectivity (and neuron cell death) occurs in early life, this feature is present also in our model, which is found to stabilize neuronal response to stimuli
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