Astrophysical and Cosmological Tests of Quantum Theory

We discuss several proposals for astrophysical and cosmological tests of quantum theory. The tests are motivated by deterministic hidden-variables theories, and in particular by the view that quantum physics is merely an effective theory of an equilibrium state. The proposed tests involve searching for nonequilibrium violations of quantum theory in: primordial inflaton fluctuations imprinted on the cosmic microwave background, relic cosmological particles, Hawking radiation, photons with entangled partners inside black holes, neutrino oscillations, and particles from very distant sources.Comment: 25 pages. Amendment to section 7. Contribution to: "The Quantum Universe", special issue of Journal of Physics A, dedicated to Prof. G.-C. Ghirardi on the occasion of his seventieth birthda

Timescales for dynamical relaxation to the Born rule

We illustrate through explicit numerical calculations how the Born-rule probability densities of non-relativistic quantum mechanics emerge naturally from the particle dynamics of de Broglie-Bohm pilot-wave theory. The time evolution of a particle distribution initially not equal to the absolute square of the wave function is calculated for a particle in a two-dimensional infinite potential square well. Under the de Broglie-Bohm ontology, the box contains an objectively-existing 'pilot wave' which guides the electron trajectory, and this is represented mathematically by a Schroedinger wave function composed of a finite out-of-phase superposition of M energy eigenstates (with M ranging from 4 to 64). The electron density distributions are found to evolve naturally into the Born-rule ones and stay there; in analogy with the classical case this represents a decay to 'quantum equilibrium'. The proximity to equilibrium is characterized by the coarse-grained subquantum H-function which is found to decrease roughly exponentially towards zero over the course of time. The timescale tau for this relaxation is calculated for various values of M and the coarse-graining length epsilon. Its dependence on M is found to disagree with an earlier theoretical prediction. A power law - tau inversely proportional to M - is found to be fairly robust for all coarse-graining lengths and, although a weak dependence of tau on epsilon is observed, it does not appear to follow any straightforward scaling. A theoretical analysis is presented to explain these results. This improvement in our understanding of timescales for relaxation to quantum equilibrium is likely to be of use in the development of models of relaxation in the early universe, with a view to constraining possible violations of the Born rule in inflationary cosmology.Comment: 27 pages, 8 figures; Replacement with small number of changes reflecting referees' comment

Effect of metal clusters on the swelling of gold-fluorocarbon-polymer composite films

We have investigated the phenomenon of swelling due to acetone diffusion in fluorocarbon polymer films doped with different gold concentrations below the percolation threshold. The presence of the gold clusters in the polymer is shown to improve the mixing between the fluorocarbon polymer and the acetone, which is not a good solvent for this kind of polymers. In order to explain the experimental results the stoichiometry and the morphology of the polymer--metal system have been studied and a modified version of the Flory--Huggins model has been developed

Biofilms and cyclic di-GMP (c-di-GMP) signaling: lessons from Pseudomonas aeruginosa and other bacteria

The cyclic di-GMP (c-di-GMP) second messenger represents a signaling system that regulates many bacterial behaviors and is of key importance for driving the lifestyle switch between motile loner cells and biofilm formers. This review provides an up-to-date compendium of c-di-GMP pathways connected to biofilm formation, biofilm-associated motilities, and other functionalities in the ubiquitous and opportunistic human pathogen Pseudomonas aeruginosa. This bacterium is frequently adopted as a model organism to study bacterial biofilm formation. Importantly, its versatility and adaptation capabilities are linked with a broad range of complex regulatory networks, including a large set of genes involved in c-di-GMP biosynthesis, degradation, and transmission

Geometrical view of quantum entanglement

Although a precise description of microscopic physical problems requires a full quantum mechanical treatment, physical quantities are generally discussed in terms of classical variables. One exception is quantum entanglement which apparently has no classical counterpart. We demonstrate here how quantum entanglement may be within the de Broglie-Bohm interpretation of quantum mechanics visualized in geometrical terms, giving new insight into this mysterious phenomenon and a language to describe it. On the basis of our analysis of the dynamics of a pair of qubits, quantum entanglement is linked to concurrent motion of angular momenta in the Bohmian space of hidden variables and to the average angle between these momenta

Existential Contextuality and the Models of Meyer, Kent and Clifton

It is shown that the models recently proposed by Meyer, Kent and Clifton (MKC) exhibit a novel kind of contextuality, which we term existential contextuality. In this phenomenon it is not simply the pre-existing value but the actual existence of an observable which is context dependent. This result confirms the point made elsewhere, that the MKC models do not, as the authors claim, ``nullify'' the Kochen-Specker theorem. It may also be of some independent interest.Comment: Revtex, 7 pages, 1 figure. Replaced with published versio

Web services and historical cadastral maps: the first step in the implementation of the Web C.A.R.T.E. system

In the State Archive of Como, Northern Italy, about 15000 historical cadastral maps corresponding to 246 current municipalities of Como and Lecco districts are preserved. These maps belong to different cadastral productions: the Theresian cadastre, promoted in 1718 by Emperor Carl VI and come into force in 1760 during the reign of Maria Teresa; the Lombardo- Veneto cadastre, started in 1854 and completed, with continuous updates during the time, at the end of the century; and finally some maps of 1905 belonging to the New Lands Cadastre, the first national geometric cadastre after Italian unification of 1861. Maps have not only a considerable artistic value but mostly a cultural and historical one, since they constitute a great source to derive an accurate representation of the territory and its evolutions. For these reasons, the old maps represent nowadays a valuable instrument for historians, scholars and professionals working both in the historical research field and in the urban and territorial planning. The project Web C.A.R.T.E. (Web Catalogo e Archivio delle Rappresentazioni del Territorio e delle sue Evoluzioni), sponsored by the Fondazione Provinciale della Comunità Comasca Onlus, has been started to enhance the immense cartographic heritage of the State Archive of Como using the most recent technologies of map processing and web services. After the maps digitization step, performed by the State Archive in agreement with the interested municipalities, a georeferencing and warping procedure is needed to place the cadastral maps in the actual Italian reference system, thus making it possible to overlap them to the current cartography. Being the most of the maps divided in sheets, that have been surveyed and drawn independently from each other, the preliminary step has been to combine the sheets in a single map by applying to them a roto- translation with a scale variation. The georeferencing of unified maps has then been performed and tested in different software and GIS packages to determine the optimal solution. Finally PCI Geomatica OrthoEngine has been chosen, thanks to its variety of implemented mathematical models and to the possibility of inserting not only Ground Control Points (points of known coordinates, both in the actual cartography and in the historical map, that are used to compute the mathematical model) but also Check Points, points with known coordinates that are not included in the transformation and can therefore be used to check the model accuracy. The residuals of the transformation have then been used to determine the best georeferencing model for each cadastral map, confirming the choice with statistical techniques. The following step has been the documentation of georeference d maps in terms of metadata, a series of information needed to precisely identify the data and get information about their content, accuracy, accessibility and usage constrains. Metadata schema are currently defined by national and international standards: at the Italian level, the CNIPA (Centro Nazionale per l’Informatica nella Pubblica Amministrazione) proposed in 2006 a standard which is in agreement with the European Directive INSPIRE and defines a common set of metadata related to all kinds of geographic information used by national Public Administrations. Metadata for the historical georeferenced maps have therefore been compiled according to the Italian standard; last step has been their publication on the Internet through GeoNetwork, an open source web geo-catalogue that allows users to immediately identify a data and derive (from its metadata) information about language, spatial extent, reference system, responsible person or agency, accessibility, possible limitations on the usage, data origin and production process, and other features. Digitized and georeferenced maps, accompanied by their metadata, can finally be visualized and navigated online through the implementation of a dedicated webGIS. The realization of this viewing service implies the usage of software and tools both from the server and the client-side. Applying FOSS (Free and Open Source Software) solutions, a system with interactive functionalities and able to manage large raster maps has been developed. The entire service is currently in a test phase to verify its fulfilment of specific requests and needs expressed by experts from the State Archive; for this reason it may be possible that new and improved solutions will be introduced in the future