Physics, the fundamental science of matter and energy, encompasses all levels of nature from the subatomic to the cosmic, and underlies much of the technology around us. Understanding the physics of our universe is an essential aspect of humanity's quest to understand our environment and our place within it. Doing physics enables us to explore the interaction between environment and human society, and can help us to work towards the future sustainability of the planet. This Very Short Introduction provides an (...) overview of how this pervasive science came to be and how it works: who funds it, how physicists are trained and how they think, and how physics supports the technology we all use. Sidney Perkowitz presents the theories and outcomes of pure and applied physics from ideas of the Greek natural philosophers to modern quantum mechanics, cosmology, digital electronics and energy production. Considering its most consequential experiments, including recent results in elementary particles, gravitational waves and materials science, he also discusses outside the lab, the effects of physics on society, culture, and humanity's vision of its place in the universe. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable. (shrink)

How does the physics we know today-- a highly professionalized enterprise, inextricably linked to government and industry-- link back to its origins as a liberal art in ancient Greece? What is the path that leads from the old philosophy of nature and its concern with humankind's place in the universe to modern massive international projects that hunt down fundamental particles and industrial laboratories that manufacture marvels? John Heilbron's fascinating history of physics introduces us to Islamic astronomers and mathematicians, calculating the (...) size of the earth whilst their caliphs conquered much of it; to medieval scholar-theologians investigating light; to Galileo, Copernicus, Kepler, and Newton, measuring, and trying to explain, the universe. We visit the 'House of Wisdom' in 9th-century Baghdad; Europe's first universities; the courts of the Renaissance; the Scientific Revolution and the academies of the 18th century; the increasingly specialized world of 20th and 21st century science. Highlighting the shifting relationship between physics, philosophy, mathematics, and technology-- and the implications for humankind's self-understanding-- Heilbron explores the changing place and purpose of physics in the cultures and societies that have nurtured it over the centuries. (shrink)

This book explores how we can measure consciousness. It clarifies what consciousness is, how it can be generated from a physical system, and how it can be measured. It also shows how conscious states can be expressed mathematically and how precise predictions can be made using data from neurophysiological studies.

Recently Díaz, Hössjer and Marks (DHM) presented a Bayesian framework to measure cosmological tuning (either fine or coarse) that uses maximum entropy (maxent) distributions on unbounded sample spaces as priors for the parameters of the physical models (https://doi.org/10.1088/1475-7516/2021/07/020). The DHM framework stands in contrast to previous attempts to measure tuning that rely on a uniform prior assumption. However, since the parameters of the models often take values in spaces of infinite size, the uniformity assumption is unwarranted. This is (...) known as the normalization problem. In this paper we explain why and how the DHM framework not only evades the normalization problem but also circumvents other objections to the tuning measurement like the so called weak anthropic principle, the selection of a single maxent distribution and, importantly, the lack of invariance of maxent distributions with respect to data transformations. We also propose to treat fine-tuning as an emergence problem to avoid infinite loops in the prior distribution of hyperparameters (common to all Bayesian analysis), and explain that previous attempts to measure tuning using uniform priors are particular cases of the DHM framework. Finally, we prove a theorem, explaining when tuning is fine or coarse for different families of distributions. The theorem is summarized in a table for ease of reference, and the tuning of three physical parameters is analyzed using the conclusions of the theorem. (shrink)

The idea that there could be spatially extended mereological simples has recently been defended by a number of metaphysicians (Markosian 1998, 2004; Simons 2004; Parsons (2000) also takes the idea seriously). Peter Simons (2004) goes further, arguing not only that spatially extended mereological simples (henceforth just extended simples) are possible, but that it is more plausible that our world is composed of such simples, than that it is composed of either point-sized simples, or of atomless gunk. The difficulty for these (...) views lies in explaining why it is that the various sub-volumes of space occupied by such simples, are not occupied by proper parts of those simples. Intuitively at least, many of us find compelling the idea that spatially extended objects have proper parts at every sub-volume of the region they occupy. It seems that the defender of extended simples must reject a seemingly plausible claim, what Simons calls the geometric correspondence principle (GCP): that any (spatially) extended object has parts that correspond to the parts of the region that it occupies (Simons 2004: 371). We disagree. We think that GCP is a plausible principle. We also think it is plausible that our world is composed of extended simples. We reconcile these two notions by two means. On the one hand we pay closer attention to the physics of our world. On the other hand, we consider what happens when our concept of something—in this case space—contains elements not all of which are realized in anything, but instead key components are realized in different features of the world. (shrink)

This book is about matter. It involves our ordinary concept of matter in so far as this deals with enduring continuants that stand in contrast to the occurrents or processes in which they are involved, and concerns the macroscopic realm of middle-sized objects of the kind familiar to us on the surface of the earth and their participation in medium term processes. The emphasis will be on what science rather than philosophical intuition tells us about the world, and on chemistry (...) rather than the physics that is more usually encountered in philosophical discussions. It is the everyday science of matter characterised by differences of chemical substance that constitutes individuated macroscopic bodies of geological and biological complexity—the continuous matter of macroscopic theory and described by mass terms. -/- The discussion might be characterised as descriptive metaphysics, being content, to paraphrase Strawson’s use of the term, to describe the structure of our scientific thought about the actual world. The method in the central chapters dealing with the nature of matter will be to pursue key steps in the historical development of scientific thought about chemical substance and related concepts with a view to tracing the emergence of a systematic ontological interpretation. Aristotle’s and the Stoics’ discussions of elements and mixtures, based on a continuous view of matter, bear some resemblance to modern, macroscopic conceptions and therefore have some interest as precursors to modern views as well as being of conceptual interest in their own right. Some of the issues they raised are still reflected in modern discussions, despite the considerable increase in complexity of the subject. Other ideas, such as the intimate connection between what modern science distinguishes as substance and phase, maintained their grip on the understanding of matter until the end of the eighteenth century. These are some of the important aspects of the properties of matter that have been neglected by linguistic concerns that have dominated the recent study of mass terms and which the present study seeks to redress. It will be of interest to see how the bounds of possibility are delimited by the laws governing the appropriate use of concepts refined for the purpose of describing the behaviour of matter. But the concern with modality will not stretch to venturing into the realms of metaphysical possibility governed by philosophical speculation about individual essences and underlying natures. -/- Like many contemporary discussions of material objects, this one relies heavily on mereology. Unlike several such discussions, this one adheres to the classical principles of mereology governing the usual dyadic relations of part, overlapping, etc. and the operations of sum, product and difference. These principles apply to the mereological structure of regions of space, intervals of time, processes and quantities of matter. Material objects that gain and lose matter are not understood to gain and lose parts and don’t call for a modification of the classic dyadic mereological relations to triadic relations with the introduction of a third term referring to time. Rather, a distinction is drawn between quantities of matter, which don’t gain or lose parts over time, and individuals, which are typically constituted of different quantities of matter at different times. The proper treatment of the temporal aspect of the features of material objects is a central issue in this book. The topics falling under this heading are addressed by investigating the conditions governing the application of predicates relating time and other entities. Of particular interest here are relations between quantities of matter and times expressing substance kind, phase and mixture. (shrink)

How does the physics we know today-- a highly professionalized enterprise, inextricably linked to government and industry-- link back to its origins as a liberal art in ancient Greece? What is the path that leads from the old philosophy of nature and its concern with humankind's place in the universe to modern massive international projects that hunt down fundamental particles and industrial laboratories that manufacture marvels? John Heilbron's fascinating history of physics introduces us to Islamic astronomers and mathematicians, calculating the (...) size of the earth whilst their caliphs conquered much of it; to medieval scholar-theologians investigating light; to Galileo, Copernicus, Kepler, and Newton, measuring, and trying to explain, the universe. We visit the 'House of Wisdom' in 9th-century Baghdad; Europe's first universities; the courts of the Renaissance; the Scientific Revolution and the academies of the 18th century; the increasingly specialized world of 20th and 21st century science. Highlighting the shifting relationship between physics, philosophy, mathematics, and technology-- and the implications for humankind's self-understanding-- Heilbron explores the changing place and purpose of physics in the cultures and societies that have nurtured it over the centuries. (shrink)

This article examines the relation between commercial activity and knowledge-making, looking at hatmakers in order to open up a more general question about the overlap between the knowledge practices of 19th-century science and those of everyday commercial culture of the time. Phrenology also claims attention here, since it can be said to have occupied an intermediate position between science and commerce. From time to time during the first half of the century, phrenologists attended to hatmakers in the hope of gleaning (...) knowledge from their commercial experience, but after about 1860, scientific craniometers took a very different view. Physical anthropologists like Paul Broca believed that the skull was the key source of data on which to build a scientific anthropology of race or ethnicity. Observers drew the attention of Broca and his colleagues to the existence of a commercial device called the conformateur des chapeliers, used by hatters to determine head shape. But Broca was far less inclined to welcome hatmakers into the domain of craniology than the phrenologists had been. Whereas phrenologists had found validation in common sense, any widely available understanding of racial types was considered by Broca to be a distraction from the work of science and a potential distortion of its data. Far from the welcoming curiosity shown by London-based phrenologists, the anthropological enterprise led by Broca defined itself as scientific in part by the strictness with which it considered and dismissed such approximate and informal ways of knowing. (shrink)

In 1926, Haldane published an essay titled 'On Being the Right Size' in which he argued that the structure, function, and behavior of an organism are strongly conditioned by the physical forces that exert the greatest impact at the scale at which it exists. This chapter puts Haldane’s insight to work in the context of contemporary cell and molecular biology. Owing to their minuscule size, cells and molecules are subject to very different forces than macroscopic organisms. In (...) a sense, macroscopic and microscopic entities inhabit different “worlds”: the former is ruled by gravity and inertia, whereas the latter is governed by Brownian motion. One implication is that we should be extremely skeptical of models and analogies that seek to explain properties of microscopic entities by appealing to properties of macroscopic ones. Unfortunately, this is precisely what the appeal to engineering metaphors in molecular biology attempts to do. Molecular biologists routinely resort to such metaphors because they are familiar and intuitively intelligible. But if our machines were the size of molecules it would be impossible for them to function the way they do. It follows that we should avoid distorting biological reality by construing it in engineering terms. In this chapter I examine four key metaphors in molecular biology – “genetic program,” “cellular circuitry,” “molecular machine,” and “molecular motor” – and I argue that their deficiencies derive from their neglect of scale. I also try to explain why many biologists today appear to have forgotten the importance of scale that Haldane drew attention to in his essay. I suggest that the reason has to do with the influence of Schrödinger’s argument in 'What is Life?' regarding the stability of the gene. (shrink)

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 The human brain appears to be the most complex structure for its size in the known universe. Consequently, studies of the brain have required many models and theories at many levels that involve disciplines from basic physics, to neurosciences, psychology and philosophy. For over 2000 years the two most controversial and unresolved models of brain phenomena involve what we call _free will_ and _consciousness_. I argue that adequate models at all (...) levels require epistemic _complementarity_ – distinct necessary models that are not derivable or reducible to each other. The primitive irreducible complementarity at all levels is the _subject-object_ distinction required by an _epistemic cut_. This complementarity first arises with self-replication where a _self_, the _subject_, must be distinguished from the _non-self_, the _object_. (shrink)

The scales across which physical properties exist are vast and subtle in their effects on particular systems placed locally on such scales. For example, human experiential access is restricted only to partial segments of the mass density, size, and temperature scales of the universe. I argue that philosophers must learn to appreciate better the effects of physical scales. Specifically, thought experiments in philosophy should be more sensitive to physical scale effects, because the conclusion of a thought (...) experiment may be undermined by unintentionally ignored scale effects, and the changes required to obtain the foreground state of affairs in a thought experiment might require unacknowledged scale-spanning changes to the contextual background. I discuss four philosophical thought experiments: Putnam's Twin Earth and Brain in a Vat, Searle's Chinese Room, and Chalmers's Zombies Without Qualia. I close by briefly defending the greater interest and importance of physical possibility over logical possibility. (shrink)

If objective physics is dependent on observer properties as Einstein showed, physical reality becomes an ‘interface reality'. Einstein's principle of observer-relativity is extended to micro motions in the observer. The resulting ‘micro relativity’ can be studied using model universes. In a classical billiard universe, the interface is characterized by ‘micro time reversals'. These time reversals cannot be ‘edited out'. They perturb every small-mass object to be observed. And they perturb every fast-moving object to be observed. The implied ‘action noise’ (...) and a ‘velocity limit', respectively, are reminiscent of Planck's constant and the speed of light , in the real world. To check whether there exists a connection with the real world, the observer temperature can be inserted into the two fundamental constants h and c. This leads to a specific value for the ‘observer diameter’ . Search for a cell class clustered around this size in the brain would amount to a ‘Privacy-of-Physics test'. Four such ‘PoP tests’ can be indicated so far. The idea that certain relational properties of the world may be as observer-private as consciousness, is therefore falsifiable. (shrink)

The extreme sexual size dimorphism in spiders has motivated studies for many years. In many species the male can be very small relative to the female. There are several hypotheses trying to explain this fact, most of them emphasizing the role of energy in determining spider size. The aim of this paper is to review the role of energy in sexual size dimorphism of spiders, even for those spiders that do not necessarily live in high foliage, using (...) physical and allometric principles. Here we propose that the cost of transport or equivalently energy expenditure and the speed are traits under selection pressure in male spiders, favoring those of smaller size to reduce travel costs. The morphology of the spiders responds to these selective forces depending upon the lifestyle of the spiders. Climbing and bridging spiders must overcome the force of gravity. If bridging allows faster dispersal, small males would have a selective advantage by enjoying more mating opportunities. In wandering spiders with low population density and as a consequence few male–male interactions, high speed and low energy expenditure or cost of transport should be favored by natural selection. Pendulum mechanics show the advantages of long legs in spiders and their relationship with high speed, even in climbing and bridging spiders. Thus small size, compensated by long legs should be the expected morphology for a fast and mobile male spider. (shrink)

In an article in Mind (Vol. 73, No. 291, July 1964) I tried to show that there is a fundamental difference between primary and secondary qualities. The present analysis of perceived size of an object and its relation to the size of the 'objective' and the 'real' object reveals that my thesis 1 regarding visual primary qualities, viz. size and shape, while true so far as shape is concerned, has to be modified in regard to size. (...) After having criticized the usual view of size constancy, I show by means of a diagram how we may determine the location in physical space of a percept of an object. This diagram reveals at the same time how perceived size decreases gradually with increasing distance of the object from the percipient, but at a much smaller rate than the retinal image of the object. By means of the diagram I show furthermore how the perceived size may in theory vary from person to person. In conclusion a modification of my thesis 1 is suggested. (shrink)

This is a linguistic study of two primary metaphors with the same target-domain concept, “IMPORTANCE IS SIZE” and “IMPORTANCE IS WEIGHT,” in English and Chinese. It is suggested that these two primary metaphors are derived from the OBJECT image schema, abstracted from our embodied, sensorimotor experience, especially our visual and tactile perception, in dealing with physical objects in everyday life. The study focuses on size and weight adjectives in both languages and on linguistic evidence in two areas: (...) their lexicalizations of the importance senses as found in the dictionaries, and their roles in the instantiation of the two primary metaphors in natural discourse as found in the corpora. Our further analysis also shows that the primary metaphors can be manifested without explicit use of size and weight words when relevant conceptual frames in the source, evoked by other words or images, are mapped onto the target domain, thus activating the relevant region of our encyclopedic knowledge and triggering off the primary metaphors in our conceptual system. We also construct a hypothetical mapping scheme for primary metaphors based on the OBJECT image schema, in which OBJECT is mapped onto its target via three of its fundamental dimensions: SIZE, WEIGHT, and SOLIDITY. It is hoped that this mapping scheme will benefit future comparative studies of primary metaphors across languages and cultures in a more systematic way. (shrink)

A primary function of mind is to form and manipulate representations to identify and choose survival-enhancing behaviors. Representations are themselves physical systems that can be manipulated to reason about, predict, or plan actions involving the objects they designate. The field of knowledge representation and reasoning turns representation upon itself to study how representations are formed and used by biological and computer systems. Some of the most versatile and successful KRR methods have been imported from computational physics. Features of a (...) problem are mapped onto dimensions of an imaginary physical system in which solution quality is inversely related to energy. Simulating the fictitious physical system on a digital computer yields a low-energy, and hence high-quality, solution to the original problem. This paper suggests a rethinking of the traditional metaphor of cognition as execution of algorithms on a digital computer. It may be both more fruitful and more accurate to conceive of representation as mapping problem features to an energy surface, learning as identifying representations that map good solutions to low free energy, and problem solving as efficient search for low free energy states. This conception of cognition is in natural accord with Stapp's theory of efficacious conscious choice. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}. (shrink)

Dr. Vukov analyzing patients with disorders of consciousness, proposed that medical well-regarded policy recommendations cannot be justified by looking solely to patients’ actual levels of consciousness (minimally conscious state – MCS versus vegetative state – VS), but that they can be justified by looking to patients’ potential for consciousness. One objective way to estimate this potential (actual physical possibility) is to consider a neurophysiologically informed strategy. Ideally such strategy would utilize objective brain activity markers of consciousness/unconsciousness. The Operational Architectonics (...) (OA) theory of brain-mind functioning is an example of such a strategy. Besides being mathematically simple, neurophysiologically accurate, and compatible with the cognitive/phenomenal perspectives on consciousness, application of OA strategy to quantitative EEG analysis of patients in VS and MCS revealed that the absence of consciousness in VS is paralleled by impairment of overall EEG operational architecture. Specifically, neuronal assemblies become smaller, their life span shortened, and they became highly unstable and functionally disconnected (desynchronized). At the same time, fluctuating (minimal) awareness in patients in MCS was paralleled by partial restoration of EEG operational architecture (increased size, life span, and stability of neuronal assemblies, together with an increased number and strength of functional connections among them), approaching the level found in healthy fully conscious participants. Moreover OA strategy to EEG analysis allowed predicting the emergence of consciousness in VS patients after six years following the brain trauma. Therefore, the OA methodology could reliably predict which patients may regain consciousness, and thus determine which patients may have the potential for consciousness. (shrink)

: This work proposes the methodology to obtain a correlation between the particle size of the rock material and the point load test index, in order to characterize the materials, present in mining projects in terms of resistance. For a correct development of mining activities, both open pit and underground, it is important to determine the compressive strength of the rocks, since, through it, geomechanical classifications are obtained, and thus calculate safety factors to define stabilization and/or fortification systems for (...) mining operations. This work was developed on the basis of samples from a geological formation and subsequent preparation of specimens, then they were subjected to physical tests, which can be carried out without problem in the field, and finally, the respective relationships were obtained. The results are encouraging and the equations are proposed to characterize the rock and achieve the proposed objective. Keywords: Rock, Crushing, Classification, Compression. (shrink)

Levi ben Gerson was a medieval astronomer who responded in an unusual way to the Ptolemaic tradition. He significantly modified Ptolemy’s lunar and planetary theories, in part by appealing to physical reasoning. Moreover, he depended on his own observations, with instruments he invented, rather than on observations he found in literary sources. As a result of his close attention to the variation in apparent planetary sizes, a subject entirely absent from the Almagest, he discovered a new phenomenon of Mars (...) and noticed a serious flaw in Ptolemy’s treatment of the Moon. (shrink)

Species evolve, very slowly, through selection of genes which give rise to phenotypes well adapted to their environments. The cultures, including the languages, of human communities evolve, much faster, maintaining at least a minimum level of adaptedness to the external, non- cultural environment. In the phylogenetic evolution of species, the transmission of information across generations is via copying of molecules, and innovation is by mutation and sexual recombination. In cultural evolution, the transmission of information across generations is by learning, and (...) innovation is by sporadic invention or borrowing from other cultures. This much is the foundational bedrock of evolutionary theory. But things get more complicated; there can be gene-culture co-evolution. Prior to the rise of culture, the physical environment is the only force shaping biological evolution from outside the organism, and cultures themselves are clearly constrained by the evolved biological characteristics of their members. But cultures become part of the external environment, and influence the course of biological evolution. For example, altruistic cultures with developed medical knowledge reduce the cost to the individual of carrying genes disposing to certain pathologies (such as diabetes); and such genes become more widespread in the populations maintaining such cultures. Assortative mating can affect biological evolution, and particular cultures may influence the factors which are sorted for in mating. (For a careful discussion of the effects of cultural evolution on natural selection, see Cavalli-Sforza and Bodmer, 1971:774- 804). This paper examines mechanisms involved in the co-evolution of a biological trait, the critical period for language acquisition, and a property of human cultures, the size of their languages. A gene/culture interaction will be shown that can be described as a kind of symbiosis, but perhaps more aptly as an `arms race'. In this introduction, we will sketch the basic mechanics of the interaction in very broad terms; the rest of the paper will explain and justify the details. The implications of our model for second language acquisition are given toward the end of the paper. (shrink)

In futsal there are two referees on the playing court and their capacity to respond to physical and physiological demands imposed during the game is essential for the success. The futsal characteristics such as size pitch, referees position and rules of games or type of league could impose specific physical efforts probably. The aim of this study were to analyze the physical demands of eight elite referees from seven matches of Spanish Futsal Cup 2020. The (...) class='Hi'>physical activity of each referee during the match was monitored with a Local Positioning System, which was installed on futsal pitch where the matches were played. The data differences were evaluated as Paired-Samples T-Test procedure. The results revealed a similar total distance between halves. The zone 3 distance showed a significative decrease during the match in comparison to the first and second halves. The number of high-intensity acceleration and deceleration decreased in the second half of the match. Therefore, the use of the tracking device to monitoring physical performance provides knowledge of the specific activity profile from futsal referees. This information to can be useful to design more accurate the training programs. (shrink)

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against­ the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the (...) accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. We discuss microtubule-based mechanisms of the mitotic spindle positioning, a key mechanical process that shapes and patterns tissues. The magnitude of the centering forces indicates that the physical limit on the accuracy and precision of centering is set by the number of contributing microtubules rather than by thermally driven fluctuations. (shrink)

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against­ the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the (...) accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. We discuss microtubule-based mechanisms of the mitotic spindle positioning, a key mechanical process that shapes and patterns tissues. The magnitude of the centering forces indicates that the physical limit on the accuracy and precision of centering is set by the number of contributing microtubules rather than by thermally driven fluctuations. (shrink)

So far, the most prominent measure for actual truthlikeness, i.e. the likeness of a theory to the actual truth, is Ilkka Niiniluoto’s minsum definition, which is purely based on distances. A competing definition is the average distance measure proposed by Pavel Tichy and Graham Oddie. We will define three related, distance and size based, measures for actual truthlikeness and compare them with the two well-known options. However, we will start, Sect. 2, from a trio of such measures for nomic (...) truthlikeness. The nomic truth, or the true theory, here refers to what is nomically, e.g. physically, possible. In a nomic (and factual) context there are two basic kinds of theories, viz. either based on an exclusion claim or on an inclusion claim. Two-sided theories combine these claims, with the maximal claim as extreme special case. We will base truthlikeness measures for exclusion, inclusion, two-sided, and hence maximal, nomic theories on two similarity measures, one in terms of distances between conceptual possibilities and the other in terms of sizes of sets of such possibilities. In Sect. 3 we will treat actual truthlikeness as extreme special case of nomic truthlikeness, viz. assuming that there is just one nomic possibility, the actual one. Next we will compare the resulting measures mutually and with the above mentioned measures of Niiniluoto and Tichy & Oddie. Finally, in Sect. 4, we will sum up the results and explore five questions for further research. (shrink)

Zusammenfassung: Fehlinterpretierte Dokumente und ignorierte physikalische Fakten: Die Geschichte von,Hitlers Atombombe‘ muss korrigiert werden. Warum haben die deutschen Physiker während des Zweiten Weltkriegs keine Atombombe entwickelt? Seit mehr als 25 Jahren sind sich die Historiker einig, dass die deutschen Physiker wussten, wie eine Atombombe gebaut werden muss, dass aber ein Programm wie das amerikanische Manhattan‐Projekt zu ihrer Realisierung in Deutschland, erst recht während des Krieges, unmöglich war. Eine genaue Analyse aller erhaltenen Original‐Dokumente über die Arbeit an der Atombombe während des,Dritten (...) Reichs‘ zeigt jedoch erhebliche Fehler der Autoren durch unvollständige Analyse der Dokumente, falsches Verständnis naturwissenschaftlicher Erläuterungen und Ignorieren physikalischer Fakten. Es wird nachgewiesen, dass die deutschen Physiker bis zum Ende des Krieges nicht bemerkt hatten, dass eine Atombombe nur mit schnellen Neutronen realisiert werden kann. Nur Heisenberg hatte das richtige Prinzip spät erkannt, es aber nicht eindeutig kommuniziert und auch in keiner Weise physikalisch vertieft. Die physikalisch korrekte Interpretation der Dokumente zeigt, dass die deutschen Physiker während des Krieges erfolglos versuchten, einen Reaktor zu entwickeln, der auch eine Voraussetzung für den Bau einer Plutonium‐Bombe gewesen wäre. Aber sie wussten nicht, wie eine Bombe realisiert werden kann, weil sie nie an einer realistischen Theorie der Atombombe gearbeitet hatten. Summary: Misinterpreted Documents and Ignored Physical Facts: The History of ‘Hitler's Atomic Bomb’ needs to be corrected. Why have the German physicists not developed an atomic bomb during World War II? For more than 25 years, the historians agree that they knew how to build the bomb, but that a bomb‐development programme of the size of the US‐Manhattan‐Project would not have been possible in wartime Germany. A detailed analysis of all preserved documents on the German atomic bomb research during the ‘Third Reich’, however, reveals considerable mistakes by the authors due to incomplete analysis of documents, misinterpretations of scientific explanations and ignoring of physical facts. It is shown that until the end of the war the German physicists did not know that an atomic bomb can only be made with fast neutrons, except Heisenberg, who, however, discovered it rather late, did not communicate it clearly and did not study any bomb physics. The physically correct interpretation of the documents reveals that the German physicists worked unsuccessfully on a reactor, which would have been a prerequisite for a plutonium bomb. But they did not know how to build a bomb because they never worked on a realistic bomb theory. (shrink)

Zusammenfassung: Fehlinterpretierte Dokumente und ignorierte physikalische Fakten: Die Geschichte von,Hitlers Atombombe‘ muss korrigiert werden. Warum haben die deutschen Physiker während des Zweiten Weltkriegs keine Atombombe entwickelt? Seit mehr als 25 Jahren sind sich die Historiker einig, dass die deutschen Physiker wussten, wie eine Atombombe gebaut werden muss, dass aber ein Programm wie das amerikanische Manhattan‐Projekt zu ihrer Realisierung in Deutschland, erst recht während des Krieges, unmöglich war. Eine genaue Analyse aller erhaltenen Original‐Dokumente über die Arbeit an der Atombombe während des,Dritten (...) Reichs‘ zeigt jedoch erhebliche Fehler der Autoren durch unvollständige Analyse der Dokumente, falsches Verständnis naturwissenschaftlicher Erläuterungen und Ignorieren physikalischer Fakten. Es wird nachgewiesen, dass die deutschen Physiker bis zum Ende des Krieges nicht bemerkt hatten, dass eine Atombombe nur mit schnellen Neutronen realisiert werden kann. Nur Heisenberg hatte das richtige Prinzip spät erkannt, es aber nicht eindeutig kommuniziert und auch in keiner Weise physikalisch vertieft. Die physikalisch korrekte Interpretation der Dokumente zeigt, dass die deutschen Physiker während des Krieges erfolglos versuchten, einen Reaktor zu entwickeln, der auch eine Voraussetzung für den Bau einer Plutonium‐Bombe gewesen wäre. Aber sie wussten nicht, wie eine Bombe realisiert werden kann, weil sie nie an einer realistischen Theorie der Atombombe gearbeitet hatten. Summary: Misinterpreted Documents and Ignored Physical Facts: The History of ‘Hitler's Atomic Bomb’ needs to be corrected. Why have the German physicists not developed an atomic bomb during World War II? For more than 25 years, the historians agree that they knew how to build the bomb, but that a bomb‐development programme of the size of the US‐Manhattan‐Project would not have been possible in wartime Germany. A detailed analysis of all preserved documents on the German atomic bomb research during the ‘Third Reich’, however, reveals considerable mistakes by the authors due to incomplete analysis of documents, misinterpretations of scientific explanations and ignoring of physical facts. It is shown that until the end of the war the German physicists did not know that an atomic bomb can only be made with fast neutrons, except Heisenberg, who, however, discovered it rather late, did not communicate it clearly and did not study any bomb physics. The physically correct interpretation of the documents reveals that the German physicists worked unsuccessfully on a reactor, which would have been a prerequisite for a plutonium bomb. But they did not know how to build a bomb because they never worked on a realistic bomb theory. (shrink)

Power-law city-size distributions are a statistical regularity researched in many countries and urban systems. In this history of science treatise we reconsider Felix Auerbach’s paper published in 1913. We reviewed his analysis and found (i) that a constant absolute concentration, as introduced by him, is equivalent to a power-law distribution with exponent $$\approx 1$$ ≈ 1, (ii) that Auerbach describes this equivalence, and (iii) that Auerbach also pioneered the empirical analysis of city-size distributions across countries, regions, and time (...) periods. We further investigate his legacy as reflected in citations and find that important follow-up work, e.g. by Lotka (Elements of physical biology. Williams & Wilkins Company, Baltimore, 1925) and Zipf (Human behavior and the principle of least effort: an introduction to human ecology, Martino Publishing, Manfield Centre, CT (2012), 1949), does give proper reference to his discovery—but others do not. For example, only approximately 20% of city-related works citing Zipf (1949) also cite Auerbach (Petermanns Geogr Mitteilungen 59(74):74–76, 1913). To our best knowledge, Lotka (1925) was the first to describe the power-law rank-size rule as it is analyzed today. Saibante (Metron Rivista Internazionale di Statistica 7(2):53–99, 1928), building on Auerbach and Lotka, investigated the power-law rank-size rule across countries, regions, and time periods. Zipf’s achievement was to embed these findings in his monumental 1949 book. We suggest that the use of “Auerbach–Lotka–Zipf law” (or “ALZ-law”) is more appropriate than “Zipf’s law for cities”, which also avoids confusion with Zipf’s law for word frequency. We end the treatise with biographical notes on Auerbach. (shrink)

Normal 0 21 false false false ES X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The main aim of this paper is to argue on behalf of instrumentalism in the philosophy of physics. Following Theo Kuipers’ terminology of domain extension and domain restriction I claim, contradicting him, that the (...) methodology of domain revision can only support an antirealist approach to the theory of physics. The existence of both extensions and restrictions of the application domain of theoretical models and the theoretical incompatibility between successive theories provide respectively with minor and major arguments for instrumentalism in physics. (shrink)

This “fun, brain-twisting book... will make you think” as it explores more than 75 paradoxes in mathematics, philosophy, physics, and the social sciences (Sean Carroll, New York Times–bestselling author of Something Deeply Hidden) Paradox is a sophisticated kind of magic trick. A magician’s purpose is to create the appearance of impossibility, to pull a rabbit from an empty hat. Yet paradox doesn’t require tangibles, like rabbits or hats. Paradox works in the abstract, with words and concepts and symbols, to create (...) the illusion of contradiction. There are no contradictions in reality, but there can appear to be. In Sleight of Mind, Matt Cook and a few collaborators dive deeply into more than 75 paradoxes in mathematics, physics, philosophy, and the social sciences. As each paradox is discussed and resolved, Cook helps readers discover the meaning of knowledge and the proper formation of concepts—and how reason can dispel the illusion of contradiction. The journey begins with “a most ingenious paradox” from Gilbert and Sullivan’s Pirates of Penzance. Readers will then travel from Ancient Greece to cutting-edge laboratories, encounter infinity and its different sizes, and discover mathematical impossibilities inherent in elections. They will tackle conundrums in probability, induction, geometry, and game theory; perform “supertasks”; build apparent perpetual motion machines; meet twins living in different millennia; explore the strange quantum world—and much more. (shrink)

The principle of common cause asserts that positive correlations between causally unrelated events ought to be explained through the action of some shared causal factors. Reichenbachian common cause systems are probabilistic structures aimed at accounting for cases where correlations of the aforesaid sort cannot be explained through the action of a single common cause. The existence of Reichenbachian common cause systems of arbitrary finite size for each pair of non-causally correlated events was allegedly demonstrated by Hofer-Szabó and Rédei in (...) 2006. This paper shows that their proof is logically deficient, and we propose an improved proof. (shrink)

The quality of doctoral-level chemistry (N=145), computer science (N=58), geoscience (N=91), mathematics (N=115), physics (N=123), and statistics/biostatistics (N=64) programs at United States universities was assessed, using 16 measures. These measures focused on variables related to: program size; characteristics of graduates; reputational factors (scholarly quality of faculty, effectiveness of programs in educating research scholars/scientists, improvement in program quality during the last 5 years); university library size; research support; and publication records. Chapter I discusses prior attempts to assess quality in (...) graduate education, development of the study plans, and the selection of disciplines and programs to be evaluated. Chapter II discusses the methodology used, focusing on each of the assessment measures. Chapters III to VIII present, respectively, findings from the analyses of the chemistry, computer science, geoscience, mathematics, physics, and statistics/biostatistics programs. Chapter IX includes a summary of results, correlations among measures, several additional analyses, and suggestions for future studies. Among the findings reported are those indicating that mathematics programs had, on the average, the largest number of faculty (N=33) in December 1980 followed closely by physics (N=28) and chemistry (N=23), and that 80 percent of computer science students had job commitments by graduation. (Survey instruments and supporting documentation are included in appendices.) (JN). (shrink)

A partition $\{C_i\}_{i\in I}$ of a Boolean algebra Ω in a probability measure space (Ω, p) is called a Reichenbachian common cause system for the correlation between a pair A,B of events in Ω if any two elements in the partition behave like a Reichenbachian common cause and its complement; the cardinality of the index set I is called the size of the common cause system. It is shown that given any non-strict correlation in (Ω, p), and given any (...) finite natural number n > 2, the probability space (Ω,p) can be embedded into a larger probability space in such a manner that the larger space contains a Reichenbachian common cause system of size n for the correlation. (shrink)

The main aim of this study was to analyze the effects of availability of key information and intergenerational leadership on burnout divided into physical symptoms of burnout and emotional symptoms of burnout and work engagement regarding the firm size during the coronavirus disease 2019. The empirical study included 583 older employees in Slovenia who participated in the survey during the COVID-19 pandemic. Structural equation modeling was used to explore the effects between constructs. We analyzed structural paths for the (...) entire sample and for the two groups. According to the results concerning both groups, the impact of the availability of key information on emotional burnout is negative only for small companies. Contrary to that the negative impact of intergenerational leadership on emotional burnout is much stronger in large companies. Concerning the impact of physical burnout on emotional burnout, the positive impact of physical burnout exists in both types of companies but is stronger in small companies. The findings will contribute to a clearer picture and the adoption of further measures to prevent burnout in the workplace and increase work engagement concerning the firm size, especially during the COVID-19 pandemic. (shrink)

It is proposed to remove the difficulty of nonitegrability of length in the Weyl geometry by modifying the law of parallel displacement and using “standard” vectors. The field equations are derived from a variational principle slightly different from that of Dirac and involving a parameter σ. For σ=0 one has the electromagnetic field. For σ<0 there is a vector meson field. This could be the electromagnetic field with finite-mass photons, or it could be a meson field providing the “missing mass” (...) of the universe. In cosmological models the two natural gauges are the Einstein gauge and the cosmic gauge. With the latter the universe has a fixed size, but the sizes of small systems decrease with time and their masses and energies increase, thus producing the Hubble effect. The field of a particle in this gauge is investigated, and it leads to an interesting solution of the Einstein equations that raises a question about the Schwarzschild solution. (shrink)

The study which this manuscript describes involved a content analysis of television advertisements appearing in 1979 and 1989. Advertisements appearing during each of the two years were classified as to whether they embraced ecology (physical environment) themes, by subject area, by size of firm, and by industry. Several important conclusions relating to the subject matter of the study were drawn. These were that television advertisers sponsor only a moderate number of ecologically responsible commercials, some of the advertisers' sponsorship (...) may be traced to altruistic goals, the percentage of commercials with ecology themes has increased slightly from 1979 to 1989, and some changes in the topical areas that the advertisements feature have taken place. Also larger enterprises and firms in the manufacturing, retailing, and financial institution sectors sponsored relatively large numbers of ecologically responsible advertisements. (shrink)

After 1905, Einstein's miraculous year, physics would never be the same again. In those twelve months, Einstein shattered many cherished scientific beliefs with five extraordinary papers that would establish him as the world's leading physicist. This book brings those papers together in an accessible format. The best-known papers are the two that founded special relativity: On the Electrodynamics of Moving Bodies and Does the Inertia of a Body Depend on Its Energy Content? In the former, Einstein showed that absolute time (...) had to be replaced by a new absolute: the speed of light. In the second, he asserted the equivalence of mass and energy, which would lead to the famous formula E = mc 2 . The book also includes On a Heuristic Point of View Concerning the Production and Transformation of Light , in which Einstein challenged the wave theory of light, suggesting that light could also be regarded as a collection of particles. This helped to open the door to a whole new world--that of quantum physics. For ideas in this paper, he won the Nobel Prize in 1921. The fourth paper also led to a Nobel Prize, although for another scientist, Jean Perrin. On the Movement of Small Particles Suspended in Stationary Liquids Required by the Molecular-Kinetic Theory of Heat concerns the Brownian motion of such particles. With profound insight, Einstein blended ideas from kinetic theory and classical hydrodynamics to derive an equation for the mean free path of such particles as a function of the time, which Perrin confirmed experimentally. The fifth paper, A New Determination of Molecular Dimensions , was Einstein's doctoral dissertation, and remains among his most cited articles. It shows how to calculate Avogadro's number and the size of molecules. These papers, presented in a modern English translation, are essential reading for any physicist, mathematician, or astrophysicist. Far more than just a collection of scientific articles, this book presents work that is among the high points of human achievement and marks a watershed in the history of science. Coinciding with the 100th anniversary of the miraculous year, this new paperback edition includes an introduction by John Stachel, which focuses on the personal aspects of Einstein's youth that facilitated and led up to the miraculous year. (shrink)

An empirically based view of size and distance perceptual content and phenomenology is introduced, in which perceivers measure worldly size and distance against their bodies. Central principles of the formal, representational theory of the measurement of extensive magnitudes are then applied in framing the account in a precise way. The question of whether spatial-perceptual experience is “unit-free” is clarified. The framework is used to assess Dennis Proffitt's proposal that spatial setting is perceived in various “units,” “scales,” or “rulers”, (...) some of them non-spatial—distance in terms of calories burned to traverse and the like. The debate between Proffitt and Firestone about the commensurability of differing measurement scales held by Proffitt to be relied on by perceivers is then clarified and resolved. Finally, the measurement theory framed account of size and distance perception is used to illuminate Gibson’s famous but elusive contrasts between “geometrical optics” and “ecological optics” and between the “physical world” and the “animal environment”. (shrink)

ObjectiveTo determine the effects of learning interventions aimed at optimizing the quality of physical education on psychomotor, cognitive, affective and social learning outcomes in children and adolescents.DesignA systematic review and meta-analysis.Data SourcesAfter searching PsycInfo, ERIC, and SportDiscus electronic databases, we identified 135 eligible studies published between January 1, 1995 to May 1, 2021.Eligibility Criteria for Selecting StudiesWe included randomized controlled trials, quasi-experimental studies, and controlled trials that assessed the effect of a PE-based intervention against one of the four identified (...) learning domains in youth at school.ResultsOne hundred and thirty five studies with over 42,500 participants and 193 calculated effect sizes were included in the study. The mean effect across all the learning and development outcomes was small to medium. When adjusted for publication bias using the Duval and Tweedie Trim and Fill Method, this mean effect size increased to d = 0.40. Effect sizes varied significantly based on learning and development outcomes. Interventions that consistently report above or below the mean d = 0.40 effect are identified based on learning outcome. The greatest effects across interventions were witnessed in psychomotor learning outcomes followed by affective, social, and cognitive learning outcomes. A minority of PE interventions captured by this systematic review and meta-analysis reported having a negative effect on student learning and development.ConclusionThe interventions with the greatest effects on student learning and development were dependant on the learning domains. Some PE interventions with a pedagogical focus such as games-based approaches, TARGET/Mastery Teaching, and Sport Education were found to be strong investments across multiple domains. The evidence is limited however by consistency in intervention dosage, study design, and data collection instruments. The study received no internal or external funding and was not prospectively registered. (shrink)

With the awakening of people's health consciousness, the concept and practice of health promotion has become the main target of health policies throughout the world. In this study, the relationship between physical education and health promotion was examined. Art students from a university in Taoyuan were selected for research, and a total of 320 questionnaires were issued. Invalid and incomplete questionnaires were eliminated, with a total of 227 valid questionnaires. Finally, the LISREL model was used to analyze the correlation (...) between various factors and health promotion. The results of the model analysis show that in terms of basic fit, the three factors of physical education have a high correlation with the influence of physical education, reaching a significant level. In terms of overall mode fit, the overall mode fit standard χ2/Df was 1.344, less than the standard value of 3 or less, and the RMR value was 0.007, indicating that the χ2/DF and RMR result standards were appropriate, and the chi-square value was very sensitive to the sample size. Therefore, there was a positive correlation among physical education, sports participation, and health promotion. In conclusion, physical activities can improve the human body's immune function, reduce the symptoms of chronic diseases, and positively promote health. The research result is important for emphasizing the benefit of sports to art students, and provides reference for improving the quality of school physical education, and the physical and mental health level of people in Taiwan. (shrink)