Cosmological effects in the local static frame

What is the influence of cosmology (the expansion law and its acceleration, the cosmological constant...) on the dynamics and optics of a local system like the solar system, a galaxy, a cluster, a supercluster...? The answer requires the solution of Einstein equation with the local source, which tends towards the cosmological model at large distance. There is, in general, no analytic expression for the corresponding metric, but we calculate here an expansion in a small parameter, which allows to answer the question. First, we derive a static expression for the pure cosmological (Friedmann-Lema\^itre) metric, whose validity, although local, extends in a very large neighborhood of the observer. This expression appears as the metric of an osculating de Sitter model. Then we propose an expansion of the cosmological metric with a local source, which is valid in a very large neighborhood of the local system. This allows to calculate exactly the (tiny) influence of cosmology on the dynamics of the solar system: it results that, contrary to some claims, cosmological effects fail to account for the unexplained acceleration of the Pioneer probe by several order of magnitudes. Our expression provide estimations of the cosmological influence in the calculations of rotation or dispersion velocity curves in galaxies, clusters, and any type of cosmic structure, necessary for precise evaluations of dark matter and/or cosmic flows. The same metric can also be used to estimate the influence of cosmology on gravitational optics in the vicinity of such systems.Comment: to appear in Astron. & Astrop

Constraining an Expanding Locally Anisotropic metric from the Pioneer anomaly

It is discussed the possibility of a fine-tuneable contribution to the two way Doppler acceleration either towards, either outwards the Sun for heliocentric distances above 20 AU by considering a background described by an Expanding Locally Anisotropic (ELA) metric. This metric encodes both the standard local Schwarzschild gravitational effects and the cosmological Universe expansion effects allowing simultaneously to fine-tune other gravitational effects at intermediate scales, which may be tentatively interpreted as a covariant parameterization of either cold dark matter either gravitational interaction corrections. Are derived bounds for the ELA metric functional parameter by considering the bounds on the deviation from standard General Relativity imposed by the current updated limits for the Pioneer anomaly, taking in consideration both the natural outgassing and on-board radiation pressure, resulting in an average Doppler acceleration outwards the Sun of a_p = +0.4^{+2.1}_{-2.0} x 10^{-10} (m/s^2). It is also computed the mass-energy density for the ELA metric within the bounds obtained and are discussed the respective contributions to the cosmological mass-energy density which, for compatibility with the Lambda-CDM model, are included in Omega_{CDM}.Comment: 22 pages; 6 figures; based on arXiv:1102.2061 with updated estimative for Pioneer anomal

La Leichte Sprache allemande : une planification linguistique du politiquement correct

La Leichte Sprache ou « langue facile à comprendre » allemande s’adresse à des personnes souffrant de déficits cognitifs et vise une communication « sans barrière » (barrierefreie Kommunikation) par l’intermédiaire de documents réputés exempts de difficultés de décodage. Elle est promue par des associations citoyennes, comme le Netzwerk Leichte Sprache (réseau pour la langue facile à comprendre) et dispose d’une grande visibilité publique. La première partie de la contribution rappelle les motivations à l’origine de cette variété, motivations en termes de droits humains à l’égalité, puis examine deux pans différents de ce mouvement de planification linguistique : la réduction-facilitation d’une part, qui vise le corpus de la langue et correspond aux critères d’une langue construite, comme l’est l’esperanto ; d’autre part, la capacité de cet allemand régulé à remplir ses objectifs intégratifs ou non. Alors que l’objectif de la Leichte Sprache consiste à améliorer l’intelligibilité de documents écrits, l’analyse conclut que les principes de réécriture reposent sur des intuitions non expertes qui ne sont pas en mesure d’atteindre une bonne compréhension, laissant principalement subsister le geste social politiquement correct.Leichte Sprache or German “easy to understand language” is aimed at people with cognitive deficits and aims at “barrier-free” communication (barrierefreie Kommunikation) through documents deemed free of decoding difficulties. It is driven by citizens’ associations, such as the Netzwerk Leichte Sprache (network for easy to understand language) and has a high public visibility. After having recalled in the first part the motivations at the origin of this variety, motivations in terms of human rights to equality, the contribution will examine two different aspects of this linguistic planning movement: on the one hand, the work of reduction-facilitation, which aims at the corpus of the language and corresponds partly to the criteria of a constructed language, as is Esperanto; on the other hand, the ability of this regulated German to fulfil its integrative or non-integratory objectives. While its objective is to improve the intelligibility of written documents, the principles of rewriting are based on non-expert intuitions that are not able to achieve a good understanding, leaving mainly the politically correct social gesture

Le GN sans déterminant en « dialecte visuel » de l’allemand

Certains auteurs germanophones contemporains exploitent la discordance entre la présence attendue du déterminant du groupe nominal (GN) en allemand et l’absence d’actualisateur pour coder une variété germano-turque, désignée par le terme Kiez, qui signifie métonymiquement « langage des quartiers ». Un exemple en est la menace rituelle « ich mach dich messer », qu’on pourrait traduire littéralement par : « je te fais couteau » et qui correspond pragmatiquement à une signification de type « tu vas avoir affaire à mon couteau ». L’absence de tout déterminant pour le substantif Messer met en scène une langue inhabituelle pour le lecteur germanophone. La contribution analyse les réalisations et leurs effets chez deux auteurs germano-turcs contemporains : Feridun Zaimoglu dans le recueil Kanak Sprak, écrit dans cette « langue de canaques », et Emine Sevgi Özdamar dans l’ensemble de titre Mutterzunge, « Langue de la mère ».Some contemporary German-speaking authors exploit the discrepancy between the expected presence of the nominal group determinant (Gn) in German and the absence of an actualizer to code a German-Turkish variety, designated by the term Kiez, which metonymically means "language of the neighbourhoods". An example of this is the ritual threat "ich mach dich messer", which could be translated literally as: "I'll make you a knife", which pragmatically corresponds to a meaning such as "you're going to have to deal with my knife". The absence of any determinant for the noun “Messer” creates an unusual language for the German-speaking reader. The contribution analyses the achievements and effects of two contemporary German-Turkish authors: Feridun Zaimoglu in Kanak Sprak, written in this "language of the scoundrels", and Emine Sevgi Özdamar in the title set Mutterzunge, "Language of the mother"

Sprachwahl in der Auslandsgermanistik: Deutsch als Publikationssprache in Frankreic

The contribution discusses the choice of language of French Germanists in their scientific publications. Contrary to the international academic world and the spreading of English in it, this pilot study to a bigger survey shows that the discipline of German Studies in France only uses two languages: German as the object language and the lingua franca of the guild, and French as meta-language and conveying code for the national language community. However as a recent development a slight Anglicisation can be observed

An Expanding Locally Anisotropic (ELA) Metric Describing Matter in an Expanding Universe

It is suggested an expanding locally anisotropic metric (ELA) ansatz describing matter in a flat expanding universe which interpolates between the Schwarzschild (SC) metric near point-like central bodies of mass 'M' and the Robertson-Walker (RW) metric for large radial coordinate: 'ds^2=Z(cdt)2 - 1/Z (dr1-(Hr1/c) Z^(alpha/2+1/2)(cdt))^2-r1^2 dOmega', where 'Z=1-U' with 'U=2GM/(c^2r1)', 'G' is the Newton constant, 'c' is the speed of light, 'H=H(t)=\dot(a)/a' is the time-dependent Hubble rate, 'dOmega=dtheta^2+sin^2(theta) dvarphi^2' is the solid angle element, 'a' is the universe scale factor and we are employing the coordinates 'r1=ar', being 'r' the radial coordinate for which the RW metric is diagonal. For constant exponent 'alpha=alpha0=0' it is retrieved the isotropic McVittie (McV) metric and for 'alpha=alpha0=1' it is retrieved the locally anisotropic Cosmological-Schwarzschild (SCS) metric, both already discussed in the literature. However it is shown that only for constant exponent 'alpha=alpha0> 1' exists an event horizon at the SC radius 'r1=2GM/c^2' and only for 'alpha=alpha0>= 3' space-time is singularity free for this value of the radius. These bounds exclude the previous existing metrics, for which the SC radius is a naked extended singularity. In addition it is shown that for 'alpha=alpha0>5' space-time is approximately Ricci flat in a neighborhood of the event horizon such that the SC metric is a good approximation in this neighborhood. It is further shown that to strictly maintain the SC mass pole at the origin 'r1=0' without the presence of more severe singularities it is required a radial coordinate dependent correction to the exponent 'alpha(r1)=alpha0+alpha1 '2GM/(c^2 r1)' with a negative coefficient 'alpha1<0'. The energy-momentum density, pressures and equation of state are discussed.Comment: 6 pages; 2 figures; covers some of the derivations in arXiv:0907.0847 with corrected terminology and a new discussion of the event horizon

Le discours public sur la langue équitable en genre en Allemagne : refus d’une altera lingua

La contribution examine les stratégies discursives par lesquelles certains locuteurs et scripteurs refusent, en Allemagne fédérale, une langue « équitable en genre » comme variété convenant à tous les usages sociaux. Les prises de position véhémentes à son sujet s’efforcent à une destruction argumentative qui pourrait être comprise comme le refus de lui accorder un statut systémique et social : ce ne peut pas être une langue. Trois types d’arguments effectuent cette mise en altérité : (1) le refus du statut scientifique à la discussion et à la langue ; (2) le caractère risible de la langue produite ; (3) la négation du droit à l’existence de la langue équitable en genre. Le corpus est constitué d’énoncés de linguistes aussi bien que de profanes informés (écrivains, journalistes, humoristes) refusant qu’on touche à la seule vraie langue.This contribution examines the discursive strategies used by certain speakers and writers in the Federal Republic of Germany to reject a gender-inclusive language as a variety suitable for all social uses. The strong positions taken on its subject are aimed at an argumentative destruction that could be understood as a refusal to grant it a systemic and social status: it cannot be a language. Three types of argument are used to achieve this otherness (altera lingua): (1) the denial of scientific status to the discussion and to the language; (2) the ridiculousness of the language produced; (3) the denial of an existence right to gender-inclusive language. The corpus consists of statements by linguists as well as by informed speakers (writers, journalists, humorists) refusing to pervert the only true language.Der Beitrag untersucht einige Diskursstrategien, mit welchen eine geschlechtergerechte Sprache als Varietät abgelehnt wird, die alle gesellschaftlichen Funktionen der Sprache erfüllen könnte. Lautstarke bis giftige Urteile zeigen die radikale Ablehnung ihres sozialen und systemischen Status‘ durch Sprechende und Schreibende in der Bundesrepublik Deutschland: sie gilt nicht als Sprache. Drei Hauptargumente bewirken diese Andersartigkeit (altera lingua): Die Diskussion über sie und die Bildung dieser Sprache seien unwissenschaftlich, die Sprache selber lächerlich, was zur Negierung ihres Existenzrechtes führt. Äußerungen sowohl von LinguistInnen als auch von Laien (Journalisten, Schriftstellern, Kabarettisten) bilden ein Korpus von Stellungnahmen, die sich weigern, eine andere als die einzig richtige Sprache anzuerkennen

Nachbarsprachen: Historio-, Konflikt-, Kontakt- oder Ökolinguistik?

The contribution examines how the paradigms of historical, conflict, contact and ecolinguistics respectively shed different light on the relation between German and French as neighbouring languages. Historical linguistics sees the neighbourly language contacts as the result of bellicose and societal interferences; conflict linguistics centres on tensions and dominance behaviour between governments and linguistic enclaves or linguistic minorities. Contact linguistics takes account of the fact that any change in neighbourly language situations could also be seen as the result of conflict-free societal changes. Ecolinguistics follows this perspective on frame conditions – instead of historically important events – still more thoroughly, and its research focus on „linguistic landscape“ exposes bilingual landscapes as compensation for the loss of bilingualism. The survey shows after all that conflict linguistics is not the only fertile description of neighbourly language relations

De Sitter Waves and the Zero Curvature Limit

We show that a particular set of global modes for the massive de Sitter scalar field (the de Sitter waves) allows to manage the group representations and the Fourier transform in the flat (Minkowskian) limit. This is in opposition to the usual acceptance based on a previous result, suggesting the appearance of negative energy in the limit process. This method also confirms that the Euclidean vacuum, in de Sitter spacetime, has to be preferred as far as one wishes to recover ordinary QFT in the flat limit.Comment: 9 pages, latex no figure, to appear in Phys. Rev.

Cosmological Redshift in FRW Metrics with Constant Spacetime Curvature

Cosmological redshift z grows as the Universe expands and is conventionally viewed as a third form of redshift, beyond the more traditional Doppler and gravitational effects seen in other applications of general relativity. In this paper, we examine the origin of redshift in the Friedmann-Robertson-Walker metrics with constant spacetime curvature, and show that---at least for the static spacetimes---the interpretation of z as due to the "stretching" of space is coordinate dependent. Namely, we prove that redshift may also be calculated solely from the effects of kinematics and gravitational acceleration. This suggests that its dependence on the expansion factor is simply a manifestation of the high degree of symmetry in FRW, and ought not be viewed as evidence in support of the idea that space itself is expanding.Comment: Accepted for publication in MNRA