A Clifford-algebraic interpretation is proposed of the charge, mass, spin relationship found recently by Cooperstock and Faraoini, which was based on the Kerr–Newman metric solutions of the Einstein–Maxwell equations. The components of the polymomentum associated with a Clifford polyparticle in four dimensions provide for such a charge, mass, spin relationship without the problems encountered in Kaluza–Klein compactifications which furnish an unphysically large value for the electron charge. A physical reasoning behind such charge, mass, spin relationship is provided, (...) followed by a discussion on the geometrical derivation of the fine structure constant by Wyler, Smith, Gonzalez-Martin and Smilga. To finalize, the renormalization of electric charge is discussed and some remarks are made pertaining the modifications of the charge–scale relationship, when the spin of the polyparticle changes with scale, that may cast some light into the alleged Astrophysical variations of the fine structure constant. (shrink)

The magnetic dipole moment of the Kerr–Newman metric, defined by mass \, electrical charge \ and angular momentum \, is \, corresponding, for all values of \, to a gyromagnetic ratio \, which is also the value of the intrinsic gyromagnetic ratio of the electron, as first noted by Carter. Here, we argue that this result can be understood in terms of the particle-wave complementarity principle. For \ can only be defined at asymptotic spatial infinity, where the (...) metric appears to describe a spinning point particle, and therefore setting \, \, we necessarily have a model of the electron. From the Dirac equation we can construct a covariantly conserved four-current \ that is the source of the electromagnetic field generated by the charge \. The result \ then follows from the minimal gauge principle \ which is implicit in the formulation of the spinorial wave equation, and which can also be justified from the line action for a spin-1/2 point particle interacting with an external electromagnetic field, due to Berezin and Marinov. By contrast, analysis of the gyrogravito-magnetic effect, investigated classically by Wald and quantum mechanically by Adler et al., yields the result \ in all non-relativistic cases, which can be explained from the principle of equivalence. The results are in accord with the correspondence principle. (shrink)

This paper deals with those time travels mostly considered by physics, namely those in the form of the so-called closed timelike curves. Some authoritative scholars have raised doubts about the status of these journeys as proper time travels. By using David Lewis’ famous definition of time travels proposed in 1976, we show that this proper status may actually be recovered, at least in some cosmological contexts containing spacetime regions, such as those concerning black holes described by the Kerr–Newman (...) metric, that allow the formation of local closed curves. But, the mathematical incompatibility between ordinary black hole solutions to Einstein field equations and the cosmological solutions induces us to take into consideration the more general issue pertaining to the slippery interplay between models related to local and global aspects of the world, highlighting, in particular, the different notions of time that these domains inevitably imply. This leads us to think that time is not a univocal entity of the world, but is a scale-related characteristic which claims the adoption, when investigating its ontological status, of a sort of regional approach. We also briefly dwell upon the most appropriate form of realism that such a kind of dispute between local and global models may involve. (shrink)

We continue to explore the consequences of Thermal Relativity Theory to the physics of black holes. The thermal analog of Lorentz transformations in the tangent space of the thermodynamic manifold are studied in connection to the Hawking evaporation of Schwarzschild black holes and one finds that there is no bound to the thermal analog of proper accelerations despite the maximal bound on the thermal analog of velocity given by the Planck temperature. The proper entropic infinitesimal interval corresponding to the (...) class='Hi'>Kerr–Newman black hole involves a \ non-Hessian metric with diagonal and off-diagonal terms of the form \^2 = g_{ ab } d Z^a dZ^b\), where \ are the mass, charge and angular momentum, respectively. Since the computation of the scalar curvature associated to this metric is very elaborate, to simplify matters, we focused on the singularities of the metric and found that they correspond to the extremal Kerr–Newman black hole case \ with vanishing temperature. Black holes in asymptotically Anti de Sitter spacetimes are more subtle to study since the mass turns out to be related to the enthalpy rather that the internal energy. We finalize with some remarks about the thermal-relativistic analog of proper force, the need to extend our analysis of Gibbs-Boltzmann entropy to the case of Reny and Tsallis entropies, and to complexify spacetime. (shrink)

Complexified Liénard–Wiechert potentials simplify the mathematics of Kerr–Newman particles. Here we constrain them by fiat to move along Bohmian trajectories to see if anything interesting occurs, as their equations of motion are not known. A covariant theory due to Stueckelberg is used. This paper deviates from the traditional Bohmian interpretation of quantum mechanics since the electromagnetic interactions of Kerr–Newman particles are dictated by general relativity. A Gaussian wave function is used to produce the Bohmian trajectories, which (...) are found to be multi-valued. A generalized analytic continuation is introduced which leads to an infinite number of trajectories. These include the entire set of Bohmian trajectories. This leads to multiple retarded times which come into play in complex space-time. If one weights these trajectories by their natural Bohmian weighting factors, then it is found that the particles do not radiate, that they are extended, and that they can have a finite electrostatic self energy, thus avoiding the usual divergence of the charged point particle. This effort does not in any way criticize or downplay the traditional Bohmian interpretation which does not assume the standard electromagnetic coupling to charged particles, but it suggests that a hybridization of Kerr–Newman particle theory with Bohmian mechanics might lead to interesting new physics, and maybe even the possibility of emergent quantum mechanics. (shrink)

It has been shown that for the Reissner-Nordström solution to the vacuum Einstein field equations charge, like mass, has a unique space-time signature (Marsh, Found. Phys. 38:293–300, 2008). The presence of charge results in a negative curvature. This work, which includes a discussion of effective mass, is extended here to the Kerr-Newman solution.

This book offers a more challenging appraisal of Newman’s life and thought.

Intrinsic gait variability, i.e., fluctuations in the regularity of gait patterns between repetitive cycles, is inherent to the sensorimotor system and influenced by factors such as age and pathology. Increased GV is associated with gait impairments in individuals with cerebral palsy and has been mainly studied based on spatiotemporal parameters. The present study aimed to describe kinematic GV in young people with CP and its associations with clinical impairments [i.e., passive range of motion, muscle weakness, reduced selective motor control, and (...) spasticity]. This retrospective study included 177 participants with CP representing 289 clinical gait analyses [n = 172 for unilateral CP vs. 117 for bilateral CP ]. As variability metrics, Root Mean Square Deviation for nine lower-limb kinematic parameters and Gait Standard Deviation – as composite score of the kinematic parameters – were computed for the affected and most affected side, respectively, as defined by clinical scores. GaitSD was then computed for the non/less-affected side for between leg comparisons. Uni- and multivariate linear regressions were subsequently performed on GaitSD of the affected/most affected side with all clinical impairments as independent variables. Highest RMSD were found in the transverse plane, for distal joints in the sagittal plane and for foot progression. GaitSD was not different between uCP and bCP but higher in the non-affected vs. affected side in uCP. GaitSD was associated with age, gait deviation index, muscle weakness, selectivity, and pROM. After adjustment for age and GDI, GaitSD remained associated with muscle weakness and selectivity. Kinematic GV can be expressed as global indicator of variability in young people with CP given the strong correlation of RMSD for lower-limb kinematic parameters. In terms of asymmetry, increased variability of the non-affected vs. affected side may indicate contralateral compensation mechanisms in uCP. Notably muscle weakness and selectivity – but not spasticity – were associated with GaitSD. Further studies need to explore the clinical relevance of kinematic GV in CP to support the interpretation of clinical gait analyses and therapeutic decision-making. (shrink)

We investigate Kerr–Newman black holes in which a rotating charged ring-shaped singularity induces a region which contains closed timelike curves (CTCs). Contrary to popular belief, it turns out that the time orientation of the CTC is oppo- site to the direction in which the singularity or the ergosphere rotates. In this sense, CTCs “counter-rotate” against the rotating black hole. We have similar results for all spacetimes sufficiently familiar to us in which rotation induces CTCs. This motivates our conjecture (...) that perhaps this counter-rotation is not an accidental oddity particular to Kerr–Newman spacetimes, but instead there may be a general and intuitively comprehensible reason for this. (shrink)

We examine the time discontinuity in rotating space–times for which the topology of time is S1. A kinematic restriction is enforced that requires the discontinuity to be an integral number of the periodicity of time. Quantized radii emerge for which the associated tangential velocities are less than the speed of light. Using the de Broglie relationship, we show that quantum theory may determine the periodicity of time. A rotating Kerr–Newman black hole and a rigidly rotating disk of dust (...) are also considered; we find that the quantized radii do not lie in the regions that possess CTCs. (shrink)

De Cock and Kerre, in considering Poincaré paradox, observed that the intuitive notion of "approximate similarity" cannot be adequately represented by the fuzzy equivalence relations. In this note we argue that the deduction apparatus of fuzzy logic gives adequate tools with which to face the question. Indeed, a first-order theory is proposed whose fuzzy models are plausible candidates for the notion of approximate similarity. A connection between these structures and the point-free metric spaces is also established.

This paper deals with a number of technical achievements that are instrumental for a dis-solution of the so-called "Hole Argument" in general relativity. Such achievements include: 1) the analysis of the "Hole" phenomenology in strict connection with the Hamiltonian treatment of the initial value problem. The work is carried through in metric gravity for the class of Christoudoulou-Klainermann space-times, in which the temporal evolution is ruled by the "weak" ADM energy; 2) a re-interpretation of "active" diffeomorphisms as "passive and (...) metric-dependent" dynamical symmetries of Einstein's equations, a re-interpretation which enables to disclose their (up to now unknown) connection to gauge transformations on-shell; understanding such connection also enlightens the real content of the Hole Argument or, better, dis-solves it together with its alleged "indeterminism"; 3) the utilization of the Bergmann-Komar "intrinsic pseudo-coordinates", defined as suitable functionals of the Weyl curvature scalars, as tools for a peculiar gauge-fixing to the super-hamiltonian and super-momentum constraints; 4) the consequent construction of a "physical atlas" of 4-coordinate systems for the 4-dimensional "mathematical" manifold, in terms of the highly non-local degrees of freedom of the gravitational field (its four independent "Dirac observables"). Such construction embodies the "physical individuation" of the points of space-time as "point-events", independently of the presence of matter, and associates a "non-commutative structure" to each gauge fixing or four-dimensional coordinate system; 5) a clarification of the multiple definition given by Peter Bergmann of the concept of "(Bergmann) observable" in general relativity. This clarification leads to the proposal of a "main conjecture" asserting the existence of i) special Dirac's observables which are also Bergmann's observables, ii) gauge variables that are coordinate independent (namely they behave like the tetradic scalar fields of the Newman-Penrose formalism). A by-product of this achievements is the falsification of a recently advanced argument asserting the absence of (any kind of) "change" in the observable quantities of general relativity. 6) a clarification of the physical role of Dirac and gauge variables as their being related to "tidal-like" and "inertial-like" effects, respectively. This clarification is mainly due to the fact that, unlike the standard formulations of the equivalence principle, the Hamiltonian formalism allows to define notion of "force" in general relativity in a natural way; 7) a proposal showing how the physical individuation of point-events could in principle be implemented as an experimental setup and protocol leading to a "standard of space-time" more or less like atomic clocks define standards of time. We conclude that, besides being operationally essential for building measuring apparatuses for the gravitational field, the role of matter in the non-vacuum gravitational case is also that of "participating directly" in the individuation process, being involved in the determination of the Dirac observables. This circumstance leads naturally to a peculiar new kind of "structuralist" view of the general-relativistic concept of space-time, a view that embodies some elements of both the traditional "absolutist" and "relational" conceptions. In the end, space-time point-events maintain a "peculiar sort of objectivity". Some hints following from our approach for the quantum gravity programme are also given. (shrink)

A tacit assumption since the 19th Century has been that the neocortex serves as the "seat of consciousness." An unexpected challenge to that assumption arose in 1949 with the discovery that high-frequency EEG activation associated with an alert state requires the intactness of the brainstem reticular formation. This discovery became the impetus for nearly three decades of research on what came to be known as the reticular activating system. By the 1970s, however, methodological and philosophical controversies led to general abandonment (...) of subcortical theories of attention and consciousness, with a return to an almost exclusive focus upon the cortex. With recent advances in the neurosciences the focus is shifting once more, this time to the unique contributions of cortical, thalmic, and brainstem structures in mediating selective attention and perceptual awareness. This paper offers a nontechnical review of the history of these developments up to contemporary interest in the putative role of oscillatory EEG patterns in the integration of perceptual features of experience. It puts forward the thesis that a key to understanding attention and consciousness is an appreciation of contributions of the thalmus to these cognitive processes. (shrink)

Given the prevalence of social media, a nascent but important area of research is the effect of social media posting on one’s own self. It is possible that an individual’s social media posts may have predictive capacity, especially in relation to health behavior. Researchers have long used concepts from the theory of reasoned action to predict health behaviors. The theory does not account for social media, which may influence or predict health behaviors. The purpose of this study was to test (...) a model including Facebook alcohol displays and constructs from the theory of reasoned action to predict binge drinking. Incoming college freshmen from two schools (312 participants between 18 and 19 years old) were interviewed prior to (T1) and 1 year into college (T2), and their Facebook profiles were evaluated for displayed alcohol content. Path modeling was used to evaluate direct and indirect paths predicting binge drinking. Path analysis suggested that Facebook alcohol displays at T1 directly predict binge drinking at T2, while alcohol attitude both directly and indirectly predicts binge drinking. Based on these results, a preliminary model of social media presentation and action is discussed. (shrink)

Current thinking and research on consciousness and the brain.

In this article, I use a mental models computational account of representation to illustrate some details of my previously presented inferential model of scientific understanding. The hope is to shed some light on possible mechanisms behind the notion of scientific understanding. I argue that if mental models are a plausible approach to modelling cognition, then understanding can best be seen as the coupling of specific rules. I present our beliefs as ?ordinary? conditional rules, and the coupling process as one where (...) the consequent of one ordinary rule (OR) matches and activates the antecedent of the rule to which it is coupled in virtue of the activation of an intermediate ?inference? rule. I argue that on this approach knowledge of an explanation is the activation of ORs in a cognitive hierarchy, while understanding is achieved when those activated ORs are also coupled via correct inference rules. I do not directly address issues regarding the plausibility of mental models themselves. This article should therefore be seen as an exercise in refining the inferential model within an already presupposed computational setting, not one of arguing for the psychological adequacy of computational approaches. (shrink)

John Worrall recently provided an account of epistemic structural realism, which explains the success of science by arguing for the correct mathematical structure of our theories. He accounts for the historical failures of science by pointing to bloated ontological interpretations of theoretical terms. In this paper I argue that Worrall’s account suffers from five serious problems. I also show that Pierre Cruse and David Papineau have developed a rival structural realism that solves all of the problems faced by Worrall. This (...) Ramsey-sentence realism is a significant advance in the debate, but still ultimately fails for its incomplete account of reference. (shrink)

Bioethics, Volume 36, Issue 3, Page 267-273, March 2022.

The key theme in this essay is the rethinking of the human, as inspired by the work of Giorgio Agamben and Hannah Arendt. The human here is not a model or concept to be realised, just as community to which the human is linked is not an ideal, but a ‘community to come’. This is revealed only by paying close attention to modes of bearing witness to the human, as instanced, for example, by Agamben’s text, Remnants of Auschwitz. Current notions (...) of political community and the human thus need to be reassessed. Only by doing this will it be possible to address the crucial issues that currently confront human rights—issues such as the tension between the principle of universal human rights and that of state sovereignty, the growing problem of statelessness, and the reduction of human rights to biopolitical humanitarianism. (shrink)

To explore 3- to 7-year-old children's developing understanding of human and non-human minds, a battery of "background knowledge" tasks was administered to 51 American children. The children were asked to speculate about how three other intentional agents would understand various visual displays. First, children answered when they themselves did not understand the displays, then they answered after they had been given information necessary to understand the displays. Results revealed that children begin to understand the role of background knowledge around the (...) same age that they pass false-belief tasks; and that before thoroughly understanding the role of background knowledge they already begin to discriminate between different types of minds. By age four, children began to show some understanding that because of having different minds than people, God is more able and dogs are less able to understand some visual displays even with full visual access. (shrink)

This paper offers an analysis of the ethical values that have accompanied human exploration of space so far, and emphasizes the need to infuse human space activity with new ethical values by means of new and well-constructed legislation. One of the values that we deem particularly important in the creation of a new approach towards space exploration is care for the natural environment, including the space environment.

Janet Broughton’s Descartes’s Method of Doubt1 is a systematic study of the role of doubt in Descartes’s epistemology. The book has two parts. Part 1 focuses on the development of doubt in the First Meditation, exploring such topics as the motivation behind methodic doubt; the targeted audience; the method’s game-like character (on her view); its relations to ancient skepticism, its reasonableness; the method’s presuppositions relative to commonsense belief; Michael Williams’s recent criticisms of Descartes; and more. Part 2 focuses on how (...) doubt figures in the constructive epistemology of the Meditations—on how Descartes employs doubt as a tool for founding knowledge. I’ll have much more to say about part 2. A careful treatment of the topics of this book has been long overdue. Broughton’s ideas are innovative, engaging, and clearly developed at every stage. The wide-ranging issues addressed remind the reader of why Descartes’s thought is of continuing philosophical interest. Throughout, her interpretation is sensitive to the exegetical concerns of scholars. This rich book deserves the attention of every serious student of Descartes. The present paper is a critical study of part 2—the more ambitious part of this highly ambitious book. I begin with an overview of Broughton’s account. Sections 2–4 contain my analysis. (shrink)

When two populations of cells within a tissue mass differ from one another in magnitude or type of intercellular adhesions, a boundary can form within the tissue, across which cells will fail to mix. This phenomenon may occur regardless of the identity of the molecules that mediate cell adhesion. If, in addition, a choice between the two adhesive states is regulated by a molecule the concentration of which is periodic in space, or in time, then alternating bands of non‐mixing tissue, (...) or segments, can form. But temporal or spatial periodicities in concentration will tend to arise for any molecule that is positively autoregu‐latory. It is therefore proposed that segmentation is a ‘generic’ property of metazoan organisms, and that metamerism would be expected to have emerged numerous times during evolution. A simple model of segmentation, based solely on differential adhesion and periodic regulation of adhesion, can account for segment properties as disparate as those seen in long and short germ band insects, and for diverse experimental results on boundary regeneration in the chick hind brain and the insect cuticle. It is suggested that the complex, multicom‐ponent segment‐forming systems found in contemporary organisms (e.g., Drosophila) are the products of evolutionary recruitment of molecular cues such as homeobox gene products, that increase the reliability and stability of metameric patterns originally templated by generic self‐organizing properties of tissues. (shrink)

L’imamat et l’occultation selon l’imamisme: Étude bibliographique et histoire des textes. By Hassan Ansari. Islamic History and Civilization, vol. 134. Leiden: Brill, 2017. Pp. xx + 310 + 268. $245, €204.

Norris, McQueen & Cutler provide two possible explanations for neighborhood effects. The first suggests that nonwords that are more similar to words tend to activate those words more than do less similar nonwords, and the second is based on sequential probabilities between phonemes. Unfortunately, neither explanation is sufficient to explain all reported neighborhood effects.