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arXiv2020

Celestial Women of Africa

The indigenous astronomy in Africa and of Africans exhibits many of the same patterns as indigenous astronomy found in other parts of the world such as with agricultural calendars established by observing celestial bodies as well as other natural phenomenon. Africa is the continent with the most countries which can be used as an indicator of its immense cultural diversity, and given such diversity there are unique local aspects to African indigenous astronomy. This chapter answers the question: How do women appear in the indigenous astronomy of Africans? The celestial bodies considered are the Sun, the Moon, the planet Venus, the Pleiades asterism and a small collection of other female celestial bodies. Examples are drawn from North, South, East, West and Central Africa with the caveat that these are merely examples from the region and not exemplars of the region. Women use the phases of the moon to track their menses, usually the moon is female as is Venus, and celestial women are used to signal how women should behave. Focusing on celestial women brings a different lens to cultural astronomy research that elucidates additional ways that that the sky is entwined in culture.

physics.hist-ph↗
arXiv2020

The Eclipse of 21 June 1629 in Beijing in the Context of the Reform of the Chinese Calendar

This paper examines the predictions made by Chinese, Muslim and Jesuit astronomers of the eclipse of 21 June 1629 in Beijing, allegedly the event that determined Emperor Chongzhen's resolution to reform the calendar using the Western method. In order to establish the accuracy of these predictions, as reported at the time by the Chinese scholar and convert Xu Guangqi, we have compared them with an accurate reconstruction of the eclipse made at NASA. In contrast with current opinions, we argue that the prediction made by the Jesuits was indeed the most accurate. It was in fact instrumental in dissipating Chongzhen's doubts about the need to entrust Jesuit missionaries serving at the Chinese court with the task of reforming the calendar, leading to the first important scientific collaboration between Europe and China.

physics.hist-ph↗
arXiv2022

Mechanical model of the inhomogeneous Maxwell's equations and of Lorentz transformations

We present a mechanical model of a quasi-elastic body (aether) which reproduces Maxwell's equations with charges and currents. Major criticism against mechanical models of electrodynamics is that any presence of charges in the known models appears to violate the continuity equation of the aether and it remains a mystery as to where the aether goes and whence it comes. We propose a solution to the mystery - in the present model the aether is always conserved. Interestingly it turns out that the charge velocity coincides with the aether velocity. In other words, the charges appear to be part of the aether itself. We interpret the electric field as the flux of the aether and the magnetic field as the torque per unit volume. In addition we show that the model is consistent with the theory of relativity, provided that we use Lorentz-Poincare interpretation (LPI) of relativity theory. We make a statistical-mechanical interpretation of the Lorentz transformations. It turns out that the length of a body is contracted by the electromagnetic field which the molecules of this same body produce. This self-interaction causes also delay of all the processes and clock-dilation results. We prove this by investigating the probability distribution for a gas of self-interacting particles. We can easily extend this analysis even to elementary particles.

physics.hist-ph↗
arXiv2021

Is the standard quantum mechanics a completely nondeterministic theory?

It is argued that although quantum theory isn't an absolutely deterministic theory, it is partially deterministic. The approach followed here is in the framework of the standard (Copenhagen interpretation of) quantum mechanics without any additional assumption or alternative interpretation. The argument is based on the conceptual meaning of determinism and by means of some well-known phenomena in the quantum world (measurement of a quantum particle spin, energy values and spatial states of an electron in atoms, the so-called wavefunction collapse problem) which are usually considered in rejecting determinism.

physics.hist-ph↗
arXiv2020

Agency in Physics

I discuss three aspects of the notion of agency from the standpoint of physics: (i) what makes a physical system an agent; (ii) the reason for agency's time orientation; (iii) the source of the information generated in choosing an action. I observe that agency is the breaking of an approximation under which dynamics appears closed. I distinguish different notions of agency, and observe that the answer to the questions above differ in different cases. I notice a structural similarity between agency and memory, that allows us to model agency, trace its time asymmetry to thermodynamical irreversibility, and identify the source of the information generated by agency in the growth of entropy. Agency is therefore a physical mechanism that transforms low entropy into information. This may be the general mechanism at the source of the whole information on which biology builds.

physics.hist-ph↗
arXiv2025

Inconsistencies and errors in traditional approaches to energy in our introductory courses

We present a critical analysis of the classical approaches to energy subjects, based on the work-energy theorem and the conservation of mechanical energy proposed in the courses of the first years of tertiary education. We show how these approaches present a series of inconsistencies and errors that are a source of conceptual difficulties among students. We then analyze a modern treatment of mechanical courses based on the results of research in physics education over the last 40 years. We place special emphasis on the principle of conservation of energy as one of the fundamental principles of nature, prioritizing the concepts of system, surrounding, and energy transfer and transformation.

physics.ed-ph↗
arXiv2022

Quantum Immortality and Non-Classical Logic

The Everett Box is a device in which an observer and a lethal quantum apparatus are isolated from the rest of the universe. On a regular basis, successive trials occur, in each of which an automatic measurement of a quantum superposition inside the apparatus either causes instant death or does nothing to the observer. From the observer's perspective, the chances of surviving $m$ trials monotonically decreases with increasing $m$. As a result, if the observer is still alive for sufficiently large $m$ she must reject any interpretation of quantum mechanics which is not the many-worlds interpretation (MWI), since surviving $m$ trials becomes vanishingly unlikely in a single world, whereas a version of the observer will necessarily survive in the branching MWI universe. Here we ask whether this conclusion still holds if rather than a classical understanding of limits built on classical logic we instead require our physics to satisfy a computability requirement by investigating the Everett Box in a model of a computational universe running on a variety of constructive logic, Recursive Constructive Mathematics. We show that although the standard Everett argument rejecting non-MWI interpretations is no longer valid, we can show that Everett's conclusion still holds within a computable universe. Thus we argue that Everett's argument is strengthened and any counter-argument must be strengthened, since it holds not only in classical logic (with embedded notions of continuity and infinity) but also in a computable logic.

physics.hist-ph↗
arXiv2020

Condición de Lorentz y ecuaciones de ondas electromagnéticas como propiedades emergentes del sistema de Maxwell

This article deals with the study of electromagnetic waves equations and the Lorentz condition, as emergent properties of Maxwell's system in the context of systems theory. To do this, the wave equations and the Helmholtz equation are first deduced. Using the displaced Dirac operator, which is closely related to the main vector calculation operators, it is possible to establish a direct connection between the solutions of the Maxwell time-harmonic system and two quaternion equations. Also, the application of the Lorentz condition to transform the time-harmonic Maxwell system into a simple quaternion equation based on the scalar and vector potentials is exposed.

physics.class-ph↗
arXiv2021

A Case Study of a Scientific Blunder. History and Philosophical Teachings

In 1988, in cooperation with a team of experimental physicists, a Condensed Matter theorist, X, published in Physical Review Letters a crucial experimental result dealing with a revolutionary new theory. The conclusions of the paper were proved incorrect a few months later. I discuss the various factors -- scientific, instrumental, but also psychological, sociological ones -- which led to this blunder. I believe this story sheds some light on the process of scientific discovery, explanation, falsification, confirmation, and errors.

physics.hist-ph↗
arXiv2020

Understanding Quantum Theory

There exist dozens of interpretations of quantum theory, but they do not seem to contribute much to understanding the theory. This paper attempts to clarify some issues that are discussed in those interpretations. The main keywords are: "Classical ontology", Indeterminism, Probability, Predictions, The necessity of classical concepts, Minimal interpretation, Lattice, Physical objects, Alternatives to quantum theory?, Measurement, Realism. One of the main points of this paper is the role of predictions in understanding any theory of physics.

quant-ph↗
arXiv2020

Epistemic Horizons: This Sentence is $\frac{1}{\sqrt{2}}(|True\rangle + |False\rangle)$

In [Found. Phys. 48.12 (2018): 1669], the notion of 'epistemic horizon' was introduced as an explanation for many of the puzzling features of quantum mechanics. There, it was shown that Lawvere's theorem, which forms the categorical backdrop to phenomena such as Gödelian incompleteness, Turing undecidability, Russell's paradox and others, applied to a measurement context, yields bounds on the maximum knowledge that can be obtained about a system, which produces many paradigmatically quantum phenomena. We give a brief presentation of the framework, and then demonstrate how it naturally yields Bell inequality violations. We then study the argument due to Einstein, Podolsky, and Rosen, and show how the counterfactual inference needed to conclude the incompleteness of the quantum formalism is barred by the epistemic horizon. Similarly, the paradoxes due to Hardy and Frauchiger-Renner are discussed, and found to turn on an inconsistent combination of information from incompatible contexts.

quant-ph↗
arXiv2020

John Ward: Memoir of a Theoretical Physicist

A scientific biography of John Ward, who was responsible for the Ward Identity in quantum electrodynamics; the first detailed calculation of the quantum entanglement of two photons in electron-positron annihilation with Maurice Pryce; the prediction of neutral weak currents in electroweak theory with Sheldon Glashow and Abdus Salam, and many other major calculations in theoretical physics.

physics.hist-ph↗
arXiv2020

The Past Hypothesis and the Nature of Physical Laws

If the Past Hypothesis underlies the arrows of time, what is the status of the Past Hypothesis? In this paper, I examine the role of the Past Hypothesis in the Boltzmannian account and defend the view that the Past Hypothesis is a candidate fundamental law of nature. Such a view is known to be compatible with Humeanism about laws, but as I argue it is also supported by a minimal non-Humean "governing" view. Some worries arise from the non-dynamical and time-dependent character of the Past Hypothesis as a boundary condition, the intrinsic vagueness in its specification, and the nature of the initial probability distribution. I show that these worries do not have much force, and in any case they become less relevant in a new quantum framework for analyzing time's arrows -- the Wentaculus. Hence, the view that the Past Hypothesis is a candidate fundamental law should be more widely accepted than it is now.

physics.hist-ph↗
arXiv2020

1000 Days to First Light: Construction of the Perth-Lowell Telescope Facility 1968-71

Negotiations began 1n 1968 for a telescope facility at Perth Observatory for NASA's International Planetary Patrol Network. 1,000 days later the telescope saw first light. The facility bears no resemblance to other observatories. Inside a dome, the telescope sits on a 42 ft tall concrete pier with a wrap-around staircase and concrete legs. Surrounding forest is similar in height to the dome, the design of which is counter intuitive. This study investigated why, at the risk of compromising performance, there was a departure from standard design, and to to identify drivers for the decision making. Observatory visitors learn of a government architect, Tadeusz Andrzejaczek who made whimsical, successive increases to the height of the structure. Though designed in collaboration with Acting Government Astronomer, Bertrand Harris, it is improbable that a public servant architect would have such influence over a scientific installation. Vibration amelioration was met by designing massive strength and rigidity into the structure. Thermal expansion and wind stresses were reduced using features such as shade fins and protective walls, and ground thermal disturbance was addressed by simply making it tall. Seeing measurements were not a significant design consideration. The facility exists with its current floor height because of successive approvals for modification. The initial design was by Harris and requests for redesigns came from him but in close negotiation the Andrzejaczek who desired a structure of futuristic shape and proportions. Harris's designs were influenced by his personal English background and the Old Perth Observatory where he worked as an astronomer. Andrzejaczek's design was influenced by an observatory in his birth city, his alignment with contemporary designers and his artistic flair.

astro-ph.IM↗
arXiv2023

Mémoire sur la mécanique quantique et l'approche ondulatoire

The Copenhagen interpretation has been the subject of much criticism, notably by De Broglie and Einstein, because it contradicts the principles of causality and realism. The aim of this essay is to study the wave mechanics as an alternative to traditional quantum mechanics, in the continuity of the ideas of Louis de Broglie: the pilot wave theory of De Broglie (where each particle is associated with a wave which guides it), De Broglie-Bohm theory, stochastic electrodynamics (where the stochastic character of particles is caused by the energy field of the fluctuating vacuum), and the analogies between quantum mechanics and hydrodynamics.

physics.hist-ph↗
arXiv2022

On the falsification of the pilot-wave interpretation of quantum mechanics and the meaning of the Born rule

Quantum mechanics has lacked a widely recognized interpretation since its birth. Many of these are still under consideration because interpretations are tough or impossible to disprove experimentally. We show how to distinguish experimentally ones assuming tiny, localized particles from those postulating realistic, non-local wave functions. It is possible thanks to a recently developed model of optical transmittance of ultra-diluted gas. This model considers the influence of each gas particle wave function on transmitted light. Its quantitative predictions are not indifferent to the interpretation of quantum mechanics. We also refer to the results of a recent experiment founded on this theory. They are in line with the predictions, which suggests the correctness of the model. Such results, if confirmed, rule out interpretations of the type of pilot-wave. In the paper, we briefly explain both the experiment and the model it is founded on. We also discuss the meaning of the Born rule.

quant-ph↗
arXiv2020

Physics, Determinism, and the Brain

This paper responds to claims that causal closure of the underlying microphysics determines brain outcomes as a matter of principle, even if we cannot hope to ever carry out the needed calculations in practice. Following two papers of mine where I claim firstly that downward causation enables genuine causal powers to occur at higher emergent levels in biology (and hence in the brain) [arXiv:2004.13591], and that secondly causal closure is in reality an interlevel affair involving even social levels [arXiv:2006.00972], Carlo Rovelli has engaged with me in a dialogue where he forcefully restates the reductionist position that microphysics alone determines all, specifically the functioning of the brain. Here I respond to that claim in depth, claiming that if one firstly takes into account the difference between synchronic and diachronic emergence, and secondly takes seriously the well established nature of biology in general and neuroscience in particular, my position is indeed correct.

physics.hist-ph↗