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Search Results: 1 - 10 of 286 matches for " Gregori "
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An Entropy-Weighted Sum over Non-Perturbative Vacua
Gregori, Andrea
High Energy Physics - Phenomenology , 2007,
Abstract: We discuss how, in a Universe restricted to the causal region connected to the observer, General Relativity implies the quantum nature of physical phenomena and directly leads to a string theory scenario, whose dynamics is ruled by a functional that weights all configurations according to their entropy. The most favoured configurations are those of minimal entropy. Along this class of vacua a four-dimensional space-time is automatically selected; when, at large volume, a description of space-time in terms of classical geometry can be recovered, the entropy-weighted sum reduces to the ordinary Feynman's path integral. What arises is a highly predictive scenario, phenomenologically compatible with the experimental observations and measurements, in which everything is determined in terms of the fundamental constants and the age of the Universe, with no room for freely-adjustable parameters. We discuss how this leads to the known spectrum of particles and interactions. Besides the computation of masses and couplings, CKM matrix elements, cosmological constant, expansion parameters of the Universe etc..., all resulting, within the degree of the approximation we used, in agreement with the experimental observations, we also discuss how this scenario passes the tests provided by cosmology and the constraints imposed by the physics of the primordial Universe.
Michael Frede (1940–2007)
Pavel Gregori
Prolegomena , 2008,
Canal network effects on the water balance in southeastern Srem
Gregori? Enike
Journal of Agricultural Sciences , 2009, DOI: 10.2298/jas0902118g
Abstract: This paper presents the results of research and analyses of the effects of a drainage canal network on the water balance of southeastern Srem. The paper was derived from a doctoral thesis which contains a detailed study of key components of the water balance of southeastern Srem, including actual amounts of water removed via the drainage canal network. A linear multiple regression model was used to establish an analytical relationship between the amounts of evacuated water (a dependent variable) and four key parameters (total precipitation, total potential evapotranspiration, average stage of the Sava River, and average groundwater level - independent variables). This correlation allows for the forecasting of hydrologic events based on historic measured data and provides answers to some important questions regarding water management and soil conservation practices. The efficiency of the drainage canal network is closely linked with its maintenance. The paper shows that canal maintenance is inadequate, mainly due to financial issues. In some parts of the studied area, drainage canals have become virtual open sewers. For this reason, the future development of the drainage system must be part of comprehensive and integrated water management in southeastern Srem. .
Relativity as classical limit in a combinatorial scenario
Andrea Gregori
Physics , 2009,
Abstract: We discuss how the finiteness and universality of the speed of light arise in the theoretical framework introduced in [1], and derive generalized coordinate transformations, that allow to investigate physical systems in a non-classical regime.
Beyond Quantum Mechanics and General Relativity
Andrea Gregori
Physics , 2010,
Abstract: In this note I present the main ideas of my proposal about the theoretical framework that could underlie, and therefore "unify", Quantum Mechanics and Relativity, and I briefly summarize the implications and predictions.
A note on the phases of natural evolution
Andrea Gregori
Physics , 2007,
Abstract: The natural evolution of life seems to proceed through steps characterized by phases of relatively rapid changes, followed by longer, more stable periods. In the light of the string-theory derived physical scenario proposed in [1], we discuss how this behaviour can be related to a sequence of resonances of the energy of natural sources of radiation and absorption energies of the DNA, responsible for mutagenesis. In a scenario in which these energy scales run independently as functions of the age of the Universe, the conditions for evolutionary mutagenesis are satisfied only at discrete points of the time axis, and for a short period, corresponding to the width of the resonance. We consider in particular the evolution of the primates through subsequent steps of increasing cranio-facial contraction, and the great Eras of life (Paleozoic, Mesozoic, Cenozoic), showing that the transitions occur at the predicted times of resonance.
Entropy, String Theory, and our World
Andrea Gregori
Physics , 2002,
Abstract: We investigate the consequences of two assumptions for String (or M) Theory, namely that: 1) all coordinates are compact and bound by the horizon of observation, 2) the ``dynamics'' of compactification is determined by the ``second law of thermodynamics'', i.e. the principle of entropy. We discuss how this leads to a phenomenologically consistent scenario for our world, both at the elementary particle's and at the cosmological level, without any fine tuning or further ``ad hoc'' constraint.
Naturally Time Dependent Cosmological Constant
Andrea Gregori
Physics , 2004,
Abstract: In the light of the proposal of hep-th/0207195, we discuss in detail the issue of the cosmological constant, explaining how can string theory naturally predict the value which is experimentally observed, without low-energy supersymmetry.
On the Time Dependence of Fundamental Constants
Andrea Gregori
Physics , 2002,
Abstract: We discuss how the results of recent measurements on the spectra of quasars are predicted by the non-perturbative solution of String Theory proposed in hep-th/0207195.
Weak Scale in Heterotic String
Andrea Gregori
Physics , 2000,
Abstract: We investigate the possibility of lowering the string scale in four dimensional heterotic models possessing a non-perturbative extension of the gauge group. In particular, we consider a class of compactifications in which the perturbative gauge sector is massive, and all the gauge bosons are non-perturbative, with a coupling independent on the Planck and string scales.
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