Moving Schwarzschild Black Hole and Modified Dispersion Relations

We study the thermodynamics of a moving Schwarzschild black hole, identifying the temperature and entropy in a relativistic scenario. Furthermore, we set arguments in a framework relating invariant geometrical quantities under global spacetime transformations and the dispersion relation of the system. We then extended these arguments in order to consider more general dispersion relations, and identify criteria to rule them out.Comment: 10 pages, no figures. Several typos fixed. New reference added. Section IV was refined according to referee's comments. Accepted in PL

Spontaneous Collapse Theories and Temporal Primitivism about Time's Direction

Two views on the direction of time can be distinguished—primitivism and non-primitivism. According to the former, time’s direction is an in-built, fundamental property of the physical world. According to the latter, time’s direction is a derivative property of a fundamentally directionless reality. In the literature, non-primitivism has been widely supported since most (if not all) our fundamental dynamical laws are time-reversal invariant. In this paper, I offer a way out to the primitivist. I argue that we do have good grounds to support a primitive direction of time in the quantum realm. The rationale depends on exploiting the metaphysical and dynamical underdetermination of quantum theories to make a case in favor of primitivism. In particular, primitivism can be grounded in spontaneous collapse theories (e.g., GRW and CSL). The specific sense in which these theories capture a primitive direction of time is that, when the ontology of the theory is seriously taken into account, it does not remain invariant under time reversal. In taking GRW with a matter-density field (GRWm), I will argue that primitivism about the direction of time can be defended in the quantum case

The physics and the philosophy of time reversal in standard quantum mechanics

A widespread view in physics holds that the implementation of time reversal in standard quantum mechanics must be given by an anti-unitary operator. In foundations and philosophy of physics, however, there has been some discussion about the conceptual grounds of this orthodoxy, largely relying on either its obviousness or its mathematical-physical virtues. My aim in this paper is to substantively change the traditional structure of the debate by highlighting the philosophical commitments underlying the orthodoxy. I argue the persuasive force of the orthodoxy greatly depends on a relationalist metaphysics of time and a by-stipulation view of time-reversal invariance. Only with such philosophical background can the orthodoxy of time reversal in standard quantum mechanics succeed and be properly justified

Time Symmetry in Three Dimensions

The notion of time reversal has caused some recent controversy in philosophy of physics. In this paper, I claim that the notion is more complex than usually thought. In particular, I contend that any account of time reversal presupposes, explicitly or implicitly, an answer to the following questions: (a) What is time-reversal symmetry predicated of? (b) What sorts of transformations should time reversal perform, and upon what? (c) What role does time-reversal symmetry play in physical theories? Each dimension, I argue, not only admits divergent answers, but also opens a dimension of analysis that feeds the complexity of time reversal: modal, metaphysical, and heuristic, respectively. The comprehension of this multi-dimensionality, I conclude, shows how philosophically rich the notion of time reversal is in philosophy of physic

Roads to the past: how to go and not to go backward in time in quantum theories

In this article I shall defend, against the conventional understanding of the matter, that two coherent and tenable approaches to time reversal can be suitably introduced in standard quantum mechanics: an “orthodox” approach that demands time reversal to be represented in terms of an anti-unitary and anti-linear time-reversal operator, and a “heterodox” approach that represents time reversal in terms of a unitary, linear time-reversal operator. The rationale shall be that the orthodox approach in quantum theories assumes a relationalist metaphysics of time, according to which time reversal is nothing but motion reversal. But, when one shifts gears and turn to a substantivalist metaphysics of time the heterodox approach to time reversal in quantum mechanics comes up in a more natural way.Fil: López, Cristian Ariel. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Filosofía "Dr. Alejandro Korn"; Argentina. Universite de Lausanne; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

La mirada del fotógrafo en la construcción del imaginario doméstico: Casa Nesbitt - Richard Neutra | Julius Shulman / Casa Obregón - Obregón & Valenzuela | Paul Beer

Màster universitari en Estudis Avançats en Arquitectura: Projecte. Procés i ProgramacióLa fotografía podría ser para la arquitectura una de las herramientas más utilizadas en la divulgación de sus ideas y en muchos casos el único mecanismo que permite la visita al proyecto. El fotógrafo acentúa en la imagen los valores que a veces el espectador no consigue ver a simple vista. La aparente semejanza o familiaridad de dos imágenes de dos proyectos localizados en lugares geográficamente distantes entre sí, aunque a primera vista formalmente cercanos, son el punto de partida de esta investigación, que se desarrolla bajo una metodología comparativa con el objeto de efectuar el estudio de las obras a través de la mirada de los fotógrafos; mas no indagar sobre la influencia que tuvo una sobre la otra. El análisis busca comprender si el modo de vida que se transmite a través de las fotografías coincide con la manera en cómo se vive cada casa. Pues a través de 64 registros encontrados de ambas obras se permite viajar hacia ellas a repasando la mirada de los fotógrafos Julius Shulman y Paul Beer

Diseño de un sistema fotovoltaico para atender la demanda de iluminación de áreas comunes y baños del bloque 1B de la Universidad Tecnológica de Pereira

El presente proyecto consiste en el diseño de un sistema fotovoltaico para atender la demanda de las áreas comunes y baños del bloque 1B de la Universidad Tecnológica de Pereira. Inicialmente se estudiaron las normas establecidas por el gobierno colombiano para la instalación de sistemas fotovoltaicos; seguidamente se hizo una introducción a los conceptos de irradiación solar, transformación de energía solar a energía eléctrica a través de módulos fotovoltaicos y componentes de un sistema solar fotovoltaico. Con la ayuda de la estación meteorológica de la UTP se obtuvieron los niveles de irradiación en la zona y se identificó el recurso solar disponible, se seleccionaron los equipos necesarios como: módulos fotovoltaicos, reguladores, acumuladores, inversores, conmutadores y protecciones DC y AC; se realizaron estudios de la energía consumida por el área escogida y la optimización de esta para una mejor viabilidad del diseño en términos economícos. Finalmente, se realizaron los cálculos correspondientes para determinar las dimensiones de cada elemento y diseñar el sistema fotovoltaico, se realizó la proyección del retorno de la inversión a 20 años y se presenta una guía básica para el mantenimiento del sistema

Quantum information or quantum coding?

In this work we will deal only with the concept of information in the communicational context, in which information is primarily something that has to be transmitted for communication purposes. The aim of the paper is to consider some arguments traditionally put forward to support the idea that quantum information is qualitatively different than classical information. On the basis of the analysis of those arguments, we will conclude that there are no reasons to admit the existence of quantum information as qualitatively different from classical information: there is only one kind of information, physically neutral, which can be encoded by means of classical or of quantum states

On the Classification between ψ−Ontic and ψ−Epistemic Ontological Models

Harrigan and Spekkens (2010) provided a categorization of quantum ontological models classifying them as $\psi-$ontic or $\psi-$epistemic if the quantum state $\psi$ describes respectively either a physical reality or mere observers' knowledge. Moreover, they claimed that Einstein - who was a supporter of the statistical interpretation of quantum mechanics - endorsed an epistemic view of $\psi$. In this essay we critically assess such a classification and some of its consequences by proposing a two-fold argumentation. Firstly, we show that Harrigan and Spekkens' categorization implicitly assumes that a complete description of a quantum system (its ontic state, $\lambda$) only concerns single, individual systems instantiating absolute, intrinsic properties. Secondly, we argue that such assumptions conflict with some current interpretations of quantum mechanics, which employ different ontic states as a complete description of quantum systems. In particular, we will show that, since in the statistical interpretation ontic states describe ensembles rather than individuals, such a view cannot be considered $\psi-$epistemic. As a consequence, the authors misinterpreted Einstein's view concerning the nature of the quantum state. Next, we will focus on Relational Quantum Mechanics and Perspectival Quantum Mechanics, which in virtue of their relational and perspectival metaphysics employ ontic states $\lambda$ dealing with relational properties. We conclude that Harrigan and Spekkens' categorization is too narrow and entails an inadequate classification of the mentioned interpretations of quantum theory. Hence, any satisfactory classification of quantum ontological models ought to take into account the variations of $\lambda$ across different interpretations of quantum mechanics