The analysis of the measurement of gravitational fields leads to the Rosenfeld inequalities. They say that, as an implication of the equivalence of the inertial and passive gravitational masses of the test body, the metric cannot be attributed to an operator that is defined in the frame of a local canonical quantum field theory. This is true for any theory containing a metric, independently of the geometric framework under consideration and the way one introduces the metric in it. Thus, to (...) establish a local quantum field theory of gravity one has to transit to non-Riemann geometry that contains (beside or instead of the metric) other geometric quantities. From this view, we discuss a Riemann–Cartan and an affine model of gravity and show them to be promising candidates of a theory of canonical quantum gravity. (shrink)

The analysis of the measurement of gravitational fields leads to the Rosenfeld inequalities. They say that, as an implication of the equivalence of the inertial and passive gravitational masses of the test body, the metric cannot be attributed to an operator that is defined in the frame of a local canonical quantum field theory. This is true for any theory containing a metric, independently of the geometric framework under consideration and the way one introduces the metric in it. Thus, to (...) establish a local quantum field theory of gravity one has to transit to non-Riemann geometry that contains (beside or instead of the metric) other geometric quantities. From this view, we discuss a Riemann–Cartan and an affine model of gravity and show them to be promising candidates of a theory of canonical quantum gravity. (shrink)

We consider a quadratic Lagrangian, in both curvature and torsion, with the aim of exploring the possibility that torsion and curvature behave as conjugate variables satisfying the commutation relations. For that proposal we first show that torsion represents a quantum correction to the classical equations of motion. We then observe that we have to introduce the spin in the Einstein theory with two spaces: a real space-time where we describe the curvature with tensors; and a complex space-time, where we describe (...) torsion with spinors. This is not satisfactory, and to overcome this contradiction we describe both mass and spin in a unique manifold, the real space-time, with the use of geometric algebra and geometric product. In that manner we are able to introduce a torsion trivector and curvature trivector that satisfy the commutation relations, opening the road for a quantum description of gravity theory. (shrink)

This work has two objectives. The first is to begin a mathematical formalism appropriate to treating particles which only interact with each otherindirectly due to hypothesized memory effects in a stochastic medium. More specifically we treat a situation in which a sequence of particles consecutively passes through a region (e.g., a measuring apparatus) in such a way that one particle leaves the region before the next one enters. We want to study a situation in which a particle may interact with (...) other particles that previously passed through the system via disturbances made in the region by these previous particles.Second, we apply the type of stochastic process appearing in this context to the stochastic interpretation of quantum mechanics to obtain a modified version of this interpretation. This version is free of many of the criticisms made against the stochastic interpretation of quantum mechanics. (shrink)

“Para que isso servirá em minha vida?” Ao longo de minha trajetória como professor do ensino secundário, ouvi esta pergunta algumas vezes. É provável que nós professores de filosofia não sejamos um alvo privilegiado dessa pergunta provocadora. Trata-se mesmo de uma questão legítima, ainda mais para nós: latinoamericanos, brasileiros, nordestinos, piauienses. Trata-se de uma pergunta que evoca um certo desespero, uma certa pressa, um tipo de agonia que é bem nossa; como quando dizemos “estou agoniado”. Queremos tudo “pra já”. Parece (...) que jamais nos daremos o direito de viver e aprender algo pelo simples fato de que o saber é bom e merece ser fruído. (shrink)

The theory of chemical symbiosis suggests that biological systems started with the collaboration of two polymeric molecules existing in early Earth: nucleic acids and peptides. Chemical symbiosis emerged when RNA-like nucleic acid polymers happened to fold into 3D structures capable to bind amino acids together, forming a proto peptidyl-transferase center. This folding catalyzed the formation of quasi-random small peptides, some of them capable to bind this ribozyme structure back and starting to form an initial layer that would produce the larger (...) subunit of the ribosome by accretion. TCS suggests that there is no chicken-and-egg problem into the emergence of biological systems as RNAs and peptides were of equal importance to the origin of life. Life has initially emerged when these two macromolecules started to interact in molecular symbiosis. Further, we suggest that life evolved into progenotes and cells due to the emergence of new layers of symbiosis. Mutualism is the strongest force in biology, capable to create novelties by emergent principles; on which the whole is bigger than the sum of the parts. TCS aims to apply the Margulian view of biology into the origins of life field. (shrink)

Este trabalho se propõe a apresentar o tema da compaixão em Schopenhauer e o da solidariedade em Rorty a partir da perspectiva filosófica de cada um dos pensadores. Não pretendemos aprofundar o problema em quaisquer das perspectivas, seja a metafísica ou a neopragmatista, mas apenas mostrar como a perspectiva de cada filósofo leva a uma concepção, ao menos aparentemente, diferente sobre um problema comum.

Many students feel despair when addressing systemic issues of ethical significance, such as climate change, and student despair has been exacerbated by the circumstances of the Covid-19 pandemic. This creates an unwelcoming space for authentic student engagement. To address the problem, we present an imaginary of radical hope, a pedagogical tool informed by trauma, for developing a brave space for class discussion. It is psychologically beneficial to acknowledge negative emotions, clearing the emotional space for students to engage. Therefore, we frame (...) ethics courses with an uncomfortable discussion, asking students to draw from their positionality and share their feelings of hope and despair, related to course material. In this paper, we explain the problem of despair motivating the project, describe the pedagogical and ethical support of our strategy, share the assignment, activity, and examples, and discuss takeaways. (shrink)

Most people assume that criminal offenders have only been convicted of a single crime. However, in reality almost half of offenders stand to be sentenced for more than one crime. The high proportion of multiple crime offenders poses a number of practical and theoretical challenges for the criminal justice system. For instance, how should courts punish multiple offenders relative to individuals who have been sentenced for a single crime? How should they be punished relative to each other? Sentencing Multiple Crimes (...) discusses these questions from the perspective of several legal theories. This volume considers questions such as the proportionality of the crimes committed, the temporal span between the crimes, and the relationship between theories about the punitive treatment of recidivists and multiple offenders. Contributors from around the world and in the fields of legal theory, philosophy, and psychology offer their perspectives to the volume. A comprehensive examination of the dynamics involved with sentencing multiple offenders has the potential to be a powerful tool for legal scholars and professionals, particularly given the practical importance of the topic and the relative dearth of research about punishment of multiple offense cases. (shrink)

Afshar et al. claim that their experiment shows a violation of the complementarity inequality. In this work, we study their claim using a modified Mach-Zehnder setup that represents a simpler version of the Afshar experiment. We find that our results are consistent with Afshar et al. experimental findings. However, we show that within standard quantum mechanics the results of the Afshar experiment do not lead to a violation of the complementarity inequality. We show that their claim originates from a particular (...) technique they use to analyze their results. In their analysis, they assume a classical concept, that particles have a definite trajectory before detection, thus, they obtain which-way information by particle detection plus path extrapolation by applying momentum conservation. This analysis technique is standard in experimental particle physics. Important discoveries such as the detection of vector bosons have been made through the application of this technique. We note that particle detection plus path extrapolation is a suitable technique within de Broglie-Bohm theory of quantum mechanics. (shrink)

The extent to which game play is experienced as engaging is an important criterion for the playability of video games. This study investigates how video games can be designed towards increased levels of experienced engagement over time. For this purpose, two experiments were conducted in which a total of 35 participants repeatedly played a video game. Results indicate that experienced engagement is based on the extent to which the game provides rich experiences as well as by the extent to which (...) the game provides a sense of control. In view of the influence of both game features and players’ expertise on the levels of experienced richness and control, it is concluded that game features should be modified over time to maintain optimal levels of engagement. (shrink)

This article provides ethical guidance on using race in health research as a variable or in defining the study population. To this end, a plain, non-exhaustive checklist is provided for researchers and research ethics committees, preceded by a brief introduction on the need for justification when using race as a variable or in defining a study population, the problem of exoticism, that distinctions pertain between race, ethnicity and ancestry, the problematic naming of races, and that race does not serve well (...) as a presumed biological construct in genetic research. (shrink)

In this paper we consider an intuitionistic variant of the modal logic S4 (which we call IS4). The novelty of this paper is that we place particular importance on the natural deduction formulation of IS4 -- our formulation has several important metatheoretic properties. In addition, we study models of IS4 -- not in the framework of Kripke semantics, but in the more general framework of category theory. This allows not only a more abstract definition of a whole class of models (...) but also a means of modelling proofs as well as provability. (shrink)

Expediente - Horizonte, Belo Horizonte, v. 17, n. 54, set.-dez. 2019.

Expediente - Horizonte, Belo Horizonte, v. 20, n. 61, jan./abr. 2022.

Expediente - Horizonte, Belo Horizonte, v. 18, n. 56, maio.-ago. 2020.