Hemeroteca de la sección ‘Ciencia y tecnología’

The First Detection of Gravitational Waves

Por • 17 ago, 2017 • Category: Ciencia y tecnología

This article deals with the first detection of gravitational waves by the advanced Laser Interferometer Gravitational Wave Observatory (LIGO) detectors on 14 September 2015, where the signal was generated by two stellar mass black holes with masses 36 M ⊙ and 29 M ⊙ that merged to form a 62 M ⊙ black hole, releasing 3 M ⊙ energy in gravitational waves, almost 1.3 billion years ago. We begin by providing a brief overview of gravitational waves, their sources and the gravitational wave detectors. We then describe in detail the first detection of gravitational waves from a binary black hole merger. We then comment on the electromagnetic follow up of the detection event with various telescopes. Finally, we conclude with the discussion on the tests of gravity and fundamental physics with the first gravitational wave detection event.

Spacetime and Physical Equivalence

Por • 8 ago, 2017 • Category: Ciencia y tecnología

In this essay I begin to lay out a conceptual scheme for: (i) analysing dualities as cases of theoretical equivalence; (ii) assessing when cases of theoretical equivalence are also cases of physical equivalence. The scheme is applied to gauge/gravity dualities. I expound what I argue to be their contribution to questions about: (iii) the nature of spacetime in quantum gravity; (iv) broader philosophical and physical discussions of spacetime. (i)-(ii) proceed by analysing duality through four contrasts. A duality will be a suitable isomorphism between models: and the four relevant contrasts are as follows: (a) Bare theory: a triple of states, quantities, and dynamics endowed with appropriate structures and symmetries; vs. interpreted theory: which is endowed with, in addition, a suitable pair of interpretative maps. (b) Extendable vs. unextendable theories: which can, respectively cannot, be extended as regards their domains of application. (c) External vs. internal intepretations: which are constructed, respectively, by coupling the theory to another interpreted theory vs. from within the theory itself. (d) Theoretical vs. physical equivalence: which contrasts formal equivalence with the equivalence of fully interpreted theories.

Logical Induction

Por • 28 jul, 2017 • Category: Ciencia y tecnología

We present a computable algorithm that assigns probabilities to every logical statement in a given formal language, and refines those probabilities over time. For instance, if the language is Peano arithmetic, it assigns probabilities to all arithmetical statements, including claims about the twin prime conjecture, the outputs of long-running computations, and its own probabilities. We show that our algorithm, an instance of what we call a logical inductor, satisfies a number of intuitive desiderata, including: (1) it learns to predict patterns of truth and falsehood in logical statements, often long before having the resources to evaluate the statements, so long as the patterns can be written down in polynomial time; (2) it learns to use appropriate statistical summaries to predict sequences of statements whose truth values appear pseudorandom; and (3) it learns to have accurate beliefs about its own current beliefs, in a manner that avoids the standard paradoxes of self-reference.

Unfolding the innovation system for the development of countries: co-evolution of Science, Technology and Production

Por • 23 jul, 2017 • Category: Ciencia y tecnología

We show that the space in which scientific, technological and economic developments interplay with each other can be mathematically shaped using pioneering multilayer network and complexity techniques. We build the tri-layered network of human activities (scientific production, patenting, and industrial production) and study the interactions among them, also taking into account the possible time delays. Within this construction we can identify which capabilities and prerequisites are needed to be competitive in a given activity, and even measure how much time is needed to transform, for instance, the technological know-how into economic wealth and scientific innovation, being able to make predictions with a very long time horizon.

Quantum theory as a principle theory: insights from an information-theoretic reconstruction

Por • 20 jul, 2017 • Category: Ciencia y tecnología

We give a condensed and accessible summary of a recent derivation of quantum theory from information-theoretic principles, and use it to study the consequences of this and other reconstructions for our conceptual understanding of the quantum world. Since these principles are to a large extent expressed in computational terminology, we argue that the hypothesis of “physics as computation”, if suitably interpreted, attains surprising explanatory power. Similarly as Jeffrey Bub and others, we conclude that quantum theory should be understood as a “principle theory of information”, and we regard this view as a partial interpretation of quantum theory. We outline three options for completion into a full-fledged interpretation of quantum theory, but argue that, despite their interpretational agnosticism, the principled reconstructions pose a challenge for existing psi-ontic interpretations. We also argue that continuous reversible time evolution can be understood as a characteristic property of quantum theory, offering a possible answer to Chris Fuchs’ search for a “glimpse of quantum reality”.

El fin de un sueño

Por • 14 jul, 2017 • Category: Ciencia y tecnología

La condena por la justicia del ex presidente Luiz Inácio Lula da Silva, es el broche final de la ofensiva contra el proyecto de convertir a Brasil en una nación independiente de los Estados Unidos y con proyección propia en el escenario regional y global. Otros dos arietes de esa estrategia llevan meses en prisión: Marcelo Odebrecht, director de la empresa que construye submarinos, y el vice-almirante Othon Luiz Pinheiro da Silva, el “padre del programa nuclear” brasileño. El principal proyecto nuclear de Brasil, el Programa Nuclear de la Marina, fue creado en 1979 y en apenas una década consiguió dominar el ciclo completo de enriquecimiento de uranio con centrifugadoras desarrolladas en el país. La reacción de Washington fue tan dura como la que propició en la década de 1950 la ofensiva contra Vargas. El país fue colocado en una “lista negra” para impedirle importar materiales para su programa nuclear.

The Information in Intuitionistic Logic

Por • 3 jul, 2017 • Category: Ciencia y tecnología

Issues about information spring up wherever one scratches the surface of logic. Here is a case that raises delicate issues of ‘factual’ versus ‘procedural’ information, or ‘statics’ versus ‘dynamics’. What does *intuitionistic logic*, perhaps the earliest source of informational and procedural thinking in contemporary logic, really tell us about information? How does its view relate to its ‘cousin’ epistemic logic? We discuss connections between intuitionistic models and recent protocol models for dynamic-epistemic logic, as well as more general issues that emerge. This paper will appear in an issue of “Synthese” edited by Luciano Floridi and Sebastian Sequoiah-Grayson, following the First Oxford Workshop in the Philosophy of Information”.

La medición y el estructuralismo científico

Por • 26 jun, 2017 • Category: Ciencia y tecnología

Este trabajo se divide en dos partes: primero, se hace un resumen del artículo Measurement theory, procedimientos de medición fundamentales y semántica de los conceptos métricos (1) de José A. Díez Calzada, y segundo, se hacen algunos comentarios al hilo del mismo. Dichas sugerencias no pretenden desde luego constituir una crítica bien articulada ni, por supuesto, una propuesta de una concepción alternativa, sino que sólo quieren resaltar los aspectos que me han parecido más importantes o problemáticos.

On the General Shape of Scales on Slide Rules

Por • 24 jun, 2017 • Category: Ciencia y tecnología

We give a thoroughful explanation of the general properties of different, general scales, corresponding to different (all possible) mathematical functions f(x), we mention and analyse many examples. These observations and statements might help us to plan and realize any specific scale we need in the future, or to understand better any interesting or miserable properties of old scales.

La machine mystique

Por • 29 may, 2017 • Category: Ciencia y tecnología

Peut-on opposer ou même séparer la foi avec les acquis de l’activité scientifique? Le théorème de Gödel a souvent été utilisé pour rendre compte de cette séparation. Le caractère abusif de cette utilisation a été bien analysé ([42], [11]). Nous nous proposons d’affiner cette analyse dans le cadre de l’hypothèse du Mécanisme Digital. Nous montrons que le Mécanisme Digital aboutit à une forme de concordisme spirituel ontologique, épistémologique et éthique. En effet, dans ce cadre, la théologie, dans le sens des (néo) platoniciens de la Grèce antique, devient ou redevient une science, et même la science la plus fondamentale en ce sens qu’elle devient capable de justifier, en principe et conceptuellement, toutes les autres. Une notion naturelle de théologie des machines, incluant la physique, est définissable, par les faits mêmes de l’incomplétude de Gödel, et de la non définissabilité de la vérité (Tarski) et de la connaissance (Kaplan-Montague [15]).