21,850 research outputs found

    Imagining Action in/Against the Anthropocene: Narrative Impasse and the Necessity of Alternatives to Effect Resistance

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    The Anthropocene has emerged as the dominant conception of the contemporary moment, centering the human individual as both responsible for and bearing the responsibility to counteract its numerous interrelated socioeconomic, political, and environmental issues including the staggering loss of biodiversity across the globe and the reality of anthropogenic climate change. This constitutes a significant psychological impasse that disempowers and disenfranchises humans living in this epoch, discouraging any substantive individual effort. Drawing on the posthuman feminist philosophy of theorists such as Rosi Braidotti and Stacy Alaimo together with a reflection of the power of science fiction as a literature of cognitive estrangement highlighting social issues, this paper reads “The Boston Hearth Project” by T.X. Watson as a short story demonstrative of an ethos of community and hope that resists the negative affects and oppressive social structures of the Anthropocene. I argue in the course of this paper that theorists and activists alike must turn to alternative narratives, such as those modelled in the emergent science fiction genre of solarpunk, in order to reject essentializing and individualizing forces and think multiply in order to realize meaningful resistance in a time of increasing fragmentation in society and destruction of the more-than-human world

    A new class of obstructions to the smoothness of null infinity

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    Expansions of the gravitational field arising from the development of asymptotically Euclidean, time symmetric, conformally flat initial data are calculated in a neighbourhood of spatial and null infinities up to order 6. To this ends a certain representation of spatial infinity as a cylinder is used. This set up is based on the properties of conformal geodesics. It is found that these expansions suggest that null infinity has to be non-smooth unless the Newman-Penrose constants of the spacetime, and some other higher order quantities of the spacetime vanish. As a consequence of these results it is conjectured that similar conditions occur if one were to take the expansions to even higher orders. Furthermore, the smoothness conditions obtained suggest that if a time symmetric initial data which is conformally flat in a neighbourhood of spatial infinity yields a smooth null infinity, then the initial data must in fact be Schwarzschildean around spatial infinity.Comment: 24 pages, 4 figure

    Asymptotic simplicity and static data

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    The present article considers time symmetric initial data sets for the vacuum Einstein field equations which in a neighbourhood of infinity have the same massless part as that of some static initial data set. It is shown that the solutions to the regular finite initial value problem at spatial infinity for this class of initial data sets extend smoothly through the critical sets where null infinity touches spatial infinity if and only if the initial data sets coincide with static data in a neighbourhood of infinity. This result highlights the special role played by static data among the class of initial data sets for the Einstein field equations whose development gives rise to a spacetime with a smooth conformal compactification at null infinity.Comment: 25 page

    Perturbations of the asymptotic region of the Schwarzschild-de Sitter spacetime

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    The conformal structure of the Schwarzschild-de Sitter spacetime is analysed using the extended conformal Einstein field equations. To this end, initial data for an asymptotic initial value problem for the Schwarzschild-de Sitter spacetime is obtained. This initial data allows to understand the singular behaviour of the conformal structure at the asymptotic points where the horizons of the Schwarzschild-de Sitter spacetime meet the conformal boundary. Using the insights gained from the analysis of the Schwarzschild-de Sitter spacetime in a conformal Gaussian gauge, we consider nonlinear perturbations close to the Schwarzschild- de Sitter spacetime in the asymptotic region. We show that small enough perturbations of asymptotic initial data for the Schwarzschild de-Sitter spacetime give rise to a solution to the Einstein field equations which exists to the future and has an asymptotic structure similar to that of the Schwarzschild-de Sitter spacetime.Comment: Accepted version in Ann. Henri Poincar\'e. Title change: "Conformal properties of the Schwarzschild-de Sitter spacetime" to "Perturbations of the asymptotic region of the Schwarzschild-de Sitter spacetime". Sections reorganised. 64 pages, 10 figure

    Asymptotic properties of the development of conformally flat data near spatial infinity

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    Certain aspects of the behaviour of the gravitational field near null and spatial infinity for the developments of asymptotically Euclidean, conformally flat initial data sets are analysed. Ideas and results from two different approaches are combined: on the one hand the null infinity formalism related to the asymptotic characteristic initial value problem and on the other the regular Cauchy initial value problem at spatial infinity which uses Friedrich's representation of spatial infinity as a cylinder. The decay of the Weyl tensor for the developments of the class of initial data under consideration is analysed under some existence and regularity assumptions for the asymptotic expansions obtained using the cylinder at spatial infinity. Conditions on the initial data to obtain developments satisfying the Peeling Behaviour are identified. Further, the decay of the asymptotic shear on null infinity is also examined as one approaches spatial infinity. This decay is related to the possibility of selecting the Poincar\'e group out of the BMS group in a canonical fashion. It is found that for the class of initial data under consideration, if the development peels, then the asymptotic shear goes to zero at spatial infinity. Expansions of the Bondi mass are also examined. Finally, the Newman-Penrose constants of the spacetime are written in terms of initial data quantities and it is shown that the constants defined at future null infinity are equal to those at past null infinity.Comment: 24 pages, 1 figur

    On the existence and convergence of polyhomogeneous expansions of zero-rest-mass fields

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    The convergence of polyhomogeneous expansions of zero-rest-mass fields in asymptotically flat spacetimes is discussed. An existence proof for the asymptotic characteristic initial value problem for a zero-rest-mass field with polyhomogeneous initial data is given. It is shown how this non-regular problem can be properly recast as a set of regular initial value problems for some auxiliary fields. The standard techniques of symmetric hyperbolic systems can be applied to these new auxiliary problems, thus yielding a positive answer to the question of existence in the original problem.Comment: 10 pages, 1 eps figur
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