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There is a mysterious twofold change in Du Châtelet's position on Newtonian attraction: from acceptance thereof as an explanatory principle in Essai sur l'optique (ca. 1738–39), to rejection in the 1740 Institutions , and returning to acceptance again in her Commentary (1756) to Newton's Principia. In this article, I suggest that we turn to the 1742 Institutions for answers. There, Du Châtelet introduces physical explanation and maintains that we can appeal to certain physical qualities (such as attraction) for explanatory force. Using this case study, I argue that the scholarship will benefit greatly from turning to the 1742 edition going forward. [ABSTRACT FROM AUTHOR]

The article discusses the role of rejection in scholarly knowledge production, emphasizing its importance in filtering out less credible scientific works. It explores how rejection helps reduce entropy and increase the dissemination of valuable knowledge, despite the subjectivity involved in the process. The text also highlights the necessity of intellectual humility among editors and reviewers to enhance the efficiency of knowledge production and ensure that valuable scientific contributions are not overlooked. [Extracted from the article]

We propose a toy model of a spherical universe made up of an exotic dark gas with temperature T in thermal equilibrium with a black body in adiabatic expansion. Each particle of this exotic gas mimics a kind of particle of dark energy represented by the vacuum energy, being quantized into virtual particles with extremely small masses that form such gas representing the own tissue of the expanding space–time governed by a negative pressure whose origin is the equation of state of vacuum, i.e., p = −ρ, where ρ is the vacuum energy density. So, each vacuum particle occupies a tiny area of space so-called Planck area L p 2 , which represents the minimum area of the whole space–time given by the spherical surface with area 4 π R H 2 , where RH is the Hubble radius. We realize that such spherical surface is the surface of the black body for representing the dark universe as if it were the surface of an expanding balloon. Thus, we are able to derive the law of universal gravitation, thus leading us to understand the cosmological anti-gravity. We estimate the very small order of magnitude of the cosmological constant and the acceleration of expansion of the dark sphere. In this toy model, as the dark universe can be thought of as a large black body, when we obtain its power and frequency of emission of radiation, we find very low values. We conclude that such radiation and frequency of the black body made up of dark energy is a background gravitational wave with very low frequency in the order of 10−17Hz due to the slight stretching of the fabric of space–time. [ABSTRACT FROM AUTHOR]

In this paper, it is argued that, contrary to some suggestions in the philosophical literature, dispositions cannot replace laws in the description of the physical world. If for a certain type of physical situation a well-working law-based account is available, then it is not possible to describe that situation equally well in terms of dispositions. Using an example consisting of four laws (Coulomb's law, Newton's law of gravitation, the rule for the composition of forces and Newton's second law), it is shown that when one attempts to replace a law-based account with a disposition-based account, the latter turns out to be either less informative or inferior with respect to theoretical virtues, such as simplicity, unification, non-triviality of predictions and explanatory power. Laws are also better suited to deal with interactions and their screening off. Using inference to the best explanation, one can conclude from this comparison that it is laws rather than dispositions that should be included in our ontological picture of nature. [ABSTRACT FROM AUTHOR]

The successful implementation of multi-generation gravity satellite missions has made significant progress in using gravity satellite observation data to monitor global mass changes. This has improved our understanding of large-scale material migration, global environmental changes in the Earth system, and facilitated research on critical environmental issues such as global sea level change monitoring, glacier melting, and groundwater extraction. Limitations in the accuracy and resolution of satellite instruments, along with factors such as modeling errors, result in global mass changes calculated using gravity satellite data being affected by noise patterns in the form of south-north stripes and signal leakage. While commonly used filtering and smoothing methods effectively mitigate the impact of south-north stripes noise, they exacerbate signal leakage problems. To address these issues and enhance the spatiotemporal resolution and accuracy of surface mass changes in the calculation of gravity satellite data, numerous scholars have developed a point-mass modeling approach based on Newton's law of universal gravitation. These methods establish a direct relationship between surface mass changes and perturbed motion of satellites, employing constraint matrices to tackle strip errors and ill-posed problems arising from downward continuation. This article examines the research progress of the point-mass modeling approach, provides a comprehensive overview of the fundamental theories and various methods employed, analyzes different strategies and characteristics of constraint matrices, and provides a concise summary of the post-processing methods associated with this approach. The comprehensive analysis presented in this article is intended to serve as a valuable reference for the future development and research of the point-mass modeling approach. [ABSTRACT FROM AUTHOR]

The article discusses the integration of physics principles, engineering, and computer programming in pre-college classrooms. It highlights the importance of implementing integrated activities that incorporate physics concepts, engineering, and computer science to broaden STEM opportunities and increase students' interest in these disciplines. The article presents a unit that allows students to explore the inverse-square law by designing and building an illuminance-distance sensor using Arduino microcontrollers. The unit follows a five-phase instructional model and includes engaging students in discussions, exploring the relationship between illuminance and distance, explaining the concepts through data analysis, and evaluating and presenting findings. The article emphasizes the benefits of this approach in teaching STEM skills and habits of mind. [Extracted from the article]

This article explores the complexities surrounding the definition of weight in physics education. It argues that current definitions of weight in pedagogical and metrological literature are unsatisfactory. The article examines weight as a local phenomenon that varies with the location and motion of the reference frame, as well as the forces and interactions involved. It discusses different definitions of weight, the concept of weightlessness, and emphasizes that weight is not an inherent characteristic of an object but depends on nongravitational forces. The article proposes a comprehensive definition of weight that considers all gravitational forces and the local centrifugal force due to celestial object rotation. Examples of weightlessness are provided, such as objects in free fall and astronauts in space. The author, Eugene Hecht, is an emeritus professor of physics with a background in optics, quantum mechanics, and college physics. [Extracted from the article]

Machine intelligence is at great height these days and has been evident with its effective provenance in almost all domains of science and technology. This work will focus on one handy and profound application of machine intelligence-time series forecast, and that too on visual data points, i.e., our objective is to predict future visual data points, given a subtle lag to work on. For the same, we would propose a deep learner, Newtonian physics informed neural network (NwPiNN) with the critical modelling capabilities of the physics informed neural networks, modelled on the laws of Newtonian physics. For computational efficacy, we would work on the gray-scale values of pixels. Since the variation in data pixel values is not only provoked by the pixel gray values but also by the velocity component of each pixel, the final prediction of the model would be a weighted average of the gray value forecast and the kinematics of each pixel, as modelled by the PINN. Besides its' proposal, NwPiNN is subjected to benchmark visual dataset, and compared with existing models for visual time series forecast, like ConvLSTM, and CNN-LSTM, and in most of the occasions, NwPiNN is found to outperform its preliminaries. [ABSTRACT FROM AUTHOR]

We assume that a sufficiently large database is available, where a physical property of interest and a number of associated ruling primitive variables or observables are stored. We introduce and test two machine learning approaches to discover possible groups or combinations of primitive variables, regardless of data origin, being it numerical or experimental: the first approach is based on regression models, whereas the second on classification models. The variable group (here referred to as the new effective good variable) can be considered as successfully found when the physical property of interest is characterized by the following effective invariant behavior: in the first method, invariance of the group implies invariance of the property up to a given accuracy; in the other method, upon partition of the physical property values into two or more classes, invariance of the group implies invariance of the class. For the sake of illustration, the two methods are successfully applied to two popular empirical correlations describing the convective heat transfer phenomenon and to the Newton's law of universal gravitation. [ABSTRACT FROM AUTHOR]

This article provides a commentary on Professor O'Donnell's interpretation of Adam Smith's concept of the invisible hand. The author, Stefano Fiori, disagrees with O'Donnell and argues that the invisible hand is indeed a metaphor. Fiori explains that O'Donnell's claim that the invisible hand is non-metaphorical is incorrect because it implies an identity between two objects without explicitly stating the terms of comparison. Fiori also addresses the issue of the referent of the invisible hand, stating that it is a matter of conjecture and not explicitly specified by Smith. Additionally, Fiori argues against O'Donnell's claim that the invisible hand is a removable and fully paraphrasable concept, stating that metaphors cannot be paraphrased without losing their metaphorical meaning. The article also explores the use of metaphors in economic theories, particularly in relation to Adam Smith's concept of the invisible hand, and discusses the role of metaphors in scientific arguments. It concludes by discussing the interpretation of Smith's work and the reconceptualization of the invisible hand in later approaches. [Extracted from the article]

We show the need of the emergence of an invariant minimum speed in the space–time. So, we propose a deformed special relativity with two limits of speed so-called Symmetrical Special Relativity (SSR). It presents a universal minimum speed V that plays the role of a preferred reference frame S V associated with vacuum. This new paradigm of space–time allows us to understand the origin of the cosmological constant Λ 0 starting from first principles given by a new kinematic invariance at low energies, which leads us to build a space–time metric with the presence of a minimum speed, so that such metric is equivalent to a de Sitter metric. In order to do that, we use a model of spherical universe with Hubble radius R H filled by a low vacuum energy density ϵ that governs the accelerated expansion of the universe with negative pressure shown by the equation of state (EOS) of vacuum given by SSR-theory (p = − ϵ). Thus, we realize that such spherical universe made up of dark energy works like a black body with adiabatic expansion thermalized with a kind of dark gas that plays the role of the dark energy. From this model of virtual particles of dark gas that fills the sphere with dark energy, we are able to derive the law of universal gravitation, allowing us to understand the cosmological anti-gravity according to the EOS of vacuum in the space–time with a minimum speed. So, we estimate the tiny order of magnitude of the cosmological constant and the acceleration of expansion of the dark sphere. In this model, as the dark universe can be thought of as a black body with Hubble radius, we obtain its power and frequency of emission of radiation for a low temperature. We conclude that such radiation is a gravitational wave with an extremely low frequency and power due to the slight stretching of the fabric of space–time, since Λ 0 is very small. [ABSTRACT FROM AUTHOR]

Dark matter is one of the great mysteries of contemporary science. In the first part of this work, we covered some general concepts that will serve as an introduction to the more specific topics analysed in this second part, such as the hypothetical particles that could constitute dark matter, and the experiments and detection techniques that have been implemented. [ABSTRACT FROM AUTHOR]

The article discusses the unexpected stability of the Sun and the unexpected instability of white dwarfs. Contrary to expectations, the Sun does not explode like a hydrogen bomb, and when a white dwarf accretes matter, it shrinks instead of getting bigger. These behaviors are attributed to Newton's law of gravitation. The article emphasizes the importance of understanding these phenomena qualitatively and highlights the role of classical mechanics and thermodynamics in explaining these celestial bodies. [Extracted from the article]

We propose a toy model of a spherical universe made up of an exotic dark gas with temperature T in thermal equilibrium with a black-body in adiabatic expansion. Each particle of this exotic gas mimics a kind of particle of dark energy. So, each dark particle occupies a very small area of space so-called Planck area L p 2 , which represents the minimum area of the whole space-time given by the spherical surface with area 4 π R H 2 , where R H is the Hubble radius. We realize that such spherical surface is the surface of the black-body for representing the dark universe as if it were the surface of an expanding balloon. Thus, we are able to derive the law of universal gravitation, thus leading us to understand the cosmological anti-gravity. We estimate the tiny order of magnitude of the cosmological constant and the acceleration of expansion of the dark sphere. In this toy model, as the dark universe can be thought of as a large black body, when we obtain its power and frequency of emission of radiation, we find very low values. We conclude that such radiation and frequency of the black body made up of dark energy is a background gravitational wave with very low frequency in the order of 1 0 − 1 7 Hz due to the slight stretching of the fabric of space-time. [ABSTRACT FROM AUTHOR]

The Standard Model is not a complete description of reality; it omits the existence of dark matter, dark energy, and an explanation as to why no CP violation has been observed. However, some of these phenomena could be explained through a new force mediated by a new boson. If such a boson were massless it would result in a power law potential and if massive the interaction would be Yukawa-like. A previous experiment employing the interactions of a micromechanical oscillator attached to spherical test mass was successful in placing the best limits on a mass–mass Yukawa-like interaction, but the data were never analyzed in the context of a power law. Here, those data are analyzed considering a power law for powers n = 1–5 where n is the number of boson exchanges. The results show that the limits obtained through power law analysis of these data are not better than the currently accepted limits. A discussion of an experiment design capable of producing better limits on power law extensions to the Standard Model is presented, and suggests that a micromechanical-oscillator-based experiment remains capable of improving the limits by at least one order of magnitude. [ABSTRACT FROM AUTHOR]

We investigate the secular evolution of a four-body planetary system, where two planets move around a binary star configuration on quasi-elliptic orbits. It is assumed that the masses of all bodies can change isotropically at different rates and the bodies attract each other according to Newton's law of universal gravitation. The purpose of this work is to investigate an influence of variability of the masses of the binary stars and their planets on the dynamical evolution of the planetary system. We consider the case of small eccentricities and inclinations of the bodies orbits and assume that their orbits do not intersect during evolution. Differential equations of the perturbed motion in the osculating analogues of canonical Poincaré elements were obtained in a general case of the many-body problem with variable masses in our previous work. Here we solve these equations numerically and investigate the secular evolution of some fictitious circumbinary 2-planet system under assumption that the two stars of the binary system lose their masses independently at different rates. In order to demonstrate the dynamical features of the equations we use the known parameters of the TOI-1338 system. Comparing the results of calculations in the cases of constant and variable masses, we show that the isotropic variability of the masses of bodies can influence substantially the secular perturbation of the orbital elements. [ABSTRACT FROM AUTHOR]

Using a mixed-method design, the study investigated the effect of the use of multiple representations on 207 (106 male and 101 female) Grade 11 students' conceptual understanding and metacognitive awareness in learning concepts in physics (mechanics). There were five multiple representations (MRs) used in this study namely: (a) drawing/sketch, (b) free-body diagram/FBD, (c) description, (d) mathematical equation, and (e) concept map (Know - Want to know - Learn). These MRs were embedded in the teacher's lesson plan as a strategy for teaching and learning selected topics in Mechanics. All these MRs were used by the teacher to discuss each lesson, and by the students to understand and do the tasks given to them. The conceptual understanding of the students was measured by obtaining the mean scores from the formative test scores in the form of a 10-item quiz for the following topics - Kinematics, Laws of Motion, and Universal Law of Gravitation. The students' metacognitive awareness was measured using the 52-item metacognitive awareness inventory (MAI) questionnaire, given before and after the implementation of the teaching-learning intervention. Students' perceptions on the use of MRs were also gathered in the form of short responses to a 5-item questionnaire. Their responses to these questions were used to elaborate and explain the results in the subcategories of the MAI. Mean scores in the formative tests revealed that students obtained passing grades in all three quizzes. Results also showed that there was an increasing trend in the students' mean scores from Quiz 1 to Quiz 3. Paired t-test also showed that the increase in the students' scores moving from Quiz 1, Quiz 2, to Quiz 3 were significant at p < 0.05. The results of the Metacognitive Awareness Inventory (MAI) questionnaire revealed that a significant difference was observed, when comparing the students' profile scores before and after the implementation of the teaching-learning intervention. The use of multiple representations (MRs) made the students more aware of how they think about learn the physics concepts. [ABSTRACT FROM AUTHOR]

The article discusses the relevance and importance of teaching physics as the study of nature's rules. The author shares personal experiences and insights into teaching physics, emphasizing the need for critical thinking skills and the appreciation of physics as an awe-inspiring subject. The article also highlights the use of questions and equations in teaching physics, as well as the significance of concepts such as Newton's second law and Einstein's equation. The author encourages educators to make science courses flavorful and awesome to engage students. [Extracted from the article]

This article discusses a thought-experiment approach to understanding the force on a current-carrying wire in a magnetic field. The author presents two thought experiments to derive the linear dependence of the magnetic force on both the current and the length of the wire. This approach offers an alternative to traditional experimental or theoretical methods and can be appreciated by physicists and students at any level. The conclusions drawn from the thought experiments are consistent with the underlying physics principles of conservation of charge and the vector nature of forces. This method can be used as a pedagogical tool to help students understand the relationship between force, current, and length in a magnetic field. [Extracted from the article]

In this study, we propose a novel methodology called Particle Dynamics Method (PDM) for identifying and quantifying influential nodes in complex networks. Inspired by Newton's three laws of motion and the universal gravitation law, PDM is based on a mathematical programming method that leverages node degrees and shortest path lengths. Unlike traditional centrality measures, PDM is easily adaptable to different network sizes and models, making it a versatile tool for network analysis. Our updated version of PDM also considers the direction of each force, resulting in more reliable results. To evaluate PDM's performance, we tested it on a set of benchmark networks with distinct characteristics and models. Our results demonstrate that PDM outperforms other methodologies in the literature, as removing the identified influential nodes results in a significant decrease in network efficiency and robustness. The key feature of PDM is its flexibility in defining distance, which can be adapted to various network types. For instance, in a transportation network, distance can be defined by the flow between nodes, while in an academic publication system, the quartile of the journal could be used. Our research not only demonstrates the effectiveness of PDM but also highlights the influence of universities in the higher education and global university ranking networks, shedding light on the dynamics of these networks. Our interdisciplinary work has significant potential for collaborations between optimization, physics, and network science. This study opens up avenues for future research, including the extension of PDM to multilayer networks and the generalization of the metrics of monolayer networks for this purpose. [ABSTRACT FROM AUTHOR]

A solid, two-component, quantum luminiferous aether is proposed to exist. Simple postulates are hypothesized, along with some physical laws and assignments. Derivations then lead to the equations of electrodynamics (Maxwell’s equations and the Lorentz force equation), Newton’s law of universal gravitation, and to two field-masses. The theory is shown to successfully meet the classic tests of general relativity: calculations for the advance of the perihelia, the Shapiro effect, and the gravitational redshift agree with experiment, and the experimental result concerning the bending of light in gravitational fields is also understood. Additionally, gravitational waves are understood, and the first of the field-masses allows for an understanding of what is presently known as dark matter. A new approach to analyzing dense objects such as white dwarfs and neutron stars is discussed, and since the theory has no singularity, a replacement for black holes is suggested. Replacing relativity with an absolute, realist, and physical model returns us to a flat Euclidean space and a separate time. Absolute simultaneity enables understanding of quantum mechanics. The underlying philosophical grounding is discussed. [ABSTRACT FROM AUTHOR]

Purpose: This work intends to investigate the rigid body's motion around a specific fixed point (analogous to Lagrange's scenario) in the presence of a gyrostatic moment (GM) besides the attraction of a Newtonian force field (NFF). This task is carried out by presuming that the body is quickly rotating about one of the major or minor principal axes of the inertia ellipsoid. Method: The controlling system of six nonlinear differential equations (DEs) along with three first integrals is boiled down to an appropriate system of two DEs in addition to only one integral. Therefore, the analytic solutions of this system are obtained utilizing the approach of Poincaré small parameter (APSP). Results: Euler's angles for the motion under investigation are derived to assess this motion at any instant of time. Additionally, phase plane graphs are displayed using computer codes to depict the stability behavior of the dynamical motion at any time. Conclusion: These achieved outcomes are thought of as a generalization of the ones that were found in some of previous works, in the absence of all applied forces and moments. This work presents a distinctive contribution in several crucial areas, particularly in engineering applications that have used the gyroscopic theory to determine the orientation and maintain the stability of various vehicles, such as spaceships, airplanes, submarines, and racing cars. [ABSTRACT FROM AUTHOR]

This essay starts with the possibility of situating Derrida's aporetic ethics in the domain of normative ethics and argues that Derrida's reflection on ethics is enrooted in the specific way he conceives the phenomenological notion of auto-affection. In the second section, I analyze, in the early work, auto-affection with signs and show its centrality in Derrida's first encounter with Levinas's philosophy. Derrida refuses to substitute the hetero-affective relation to the Other for auto-affection as the source of universal law and normativity. He does not sacrifice universality and tackles the problem of autonomous ethical decision-making even though he welcomes through affectivity the signification of the singular other, which is irreducible to conceptual, emotive, and normative self-relation. This background helps us understand the rootedness of ethical aporias in a reflection on auto-affection. [ABSTRACT FROM AUTHOR]

The enforcement of the unimodularity condition in a gravity theory by means of a Lagrange multiplier leads, in general, to inconsistencies upon quantization. This is so, in particular, when the classic linear splitting of the metric between the background and quantum fields is used. To avoid the need of introducing such a Lagrange multiplier while using the classic linear splitting, we carry out the quantization of unimodular gravity with extra Weyl symmetry by using Becchi–Rouet–Stora–Tyutin (BRST) techniques. Here, two gauge symmetries are to be gauge-fixed: transverse diffeomorphisms and Weyl transformations. We perform the gauge-fixing of the transverse diffeomorphism invariance by using BRST transformations that involve antisymmetric ghost fields. We show that these BRST transformations are compatible with the BRST transformations needed to gauge-fix the Weyl symmetry, so that they can be combined in a set of transformations generated by a single BRST operator. Newton's law of gravitation is derived within the BRST formalism we put forward as well as the Slavnov–Taylor equation. [ABSTRACT FROM AUTHOR]

In modelling atmospheric loading effects for terrestrial gravimetry, state-of-the-art approaches take advantage of numerical weather models to account for the global 3-D distribution of air masses. Deformation effects are often computed assuming the Inverse Barometer (IB) hypothesis to be generally valid over the oceans. By a revision of the IB assumption and its consequences we show that although the seafloor is not deformed by atmospheric pressure changes, there exists a fraction of ocean mass that current modelling schemes are usually not accounting for. This causes an overestimation of the atmospheric attraction effect over oceans, even when the dynamic response of the ocean to atmospheric pressure and wind is accounted through dynamic ocean models. This signal can reach a root mean square variability of a few nm s−2, depending on the location of the station. We therefore test atmospheric and non-tidal ocean loading effects at five superconducting gravimeter (SG) stations, showing that a better representation of the residual gravity variations is found when Newtonian attraction effects due to the IB response of the ocean are correctly considered. A sliding window variance analysis shows that the main reduction takes place for periods between 5 and 10 d, even for stations far away from the oceans. Since periods of non-tidal ocean mass variability closely resemble atmospheric signals recorded by SGs, we recommend to directly incorporate both an ocean component together with the IB into services that provide weather-related corrections for terrestrial gravimetry. [ABSTRACT FROM AUTHOR]

In order to solve the problems of insufficient optimization accuracy, slow convergence speed and easy to fall into local optimum in the whale optimization algorithm, this paper proposes a whale optimization algorithm with improved neighborhood search strategy. First, the algorithm generates a more evenly distributed and higher-quality initial population through an initialization strategy based on the opposite-based learning of pinhole imaging to expand the early search space of the algorithm. Secondly, it adopts improved neighborhood search strategy based on similarity and uses Mahalanobis distance and the law of universal gravitation to calculate and rank the similarity of solutions. At the same time, the algorithm counts the times of convergence oscillation. According to the algorithm iteration process, it selects the corresponding similarity ranking solution as the object to update the position and performs the second position update for the solution with most times of oscillation, so as to implement the space exploration of the target population to speed up the convergence of the algorithm and enhance the ability to jump out of the local optimum. Finally, an adaptive step size adjustment strategy is introduced, and the population convergence is adjusted using adaptive step size parameters according to the algorithm optimization process to improve the algorithm's global search performance and avoid premature convergence of the algorithm. The improved algorithm proposed in this paper is analyzed and compared with the sine–cosine optimization algorithm, artificial bee colony algorithm and three improved whale algorithms on a set of 20 test functions in low-dimensional and high-dimensional, respectively, and perform ANOVA and T-test on the simulation results. The results show that the improved algorithm proposed in this paper effectively improves the convergence accuracy and convergence speed. In addition, the improved optimization algorithm proposed in this paper is applied to the engineering optimization design. The solutions show that the improved algorithm can obtain the optimal value with higher accuracy and more stability than other algorithms, and can effectively solve the engineering design problem. [ABSTRACT FROM AUTHOR]

This manuscript investigates a dynamical system in which $ 2N $ primary particles of equal masses move in space under Newton's law of gravitation forming the vertices of antiprisms while a particle of negligible mass moves along the common axis of symmetry of the antiprisms. This $ n $-body problem that we call the restricted hip-hop $ (2N + 1) $-body problem is an extension of the generalized Sitnikov problem studied in [17] for which the primaries remain in a plane. This work also relies on an early study [14] where certain families of periodic hip-hop solutions to a $ 2N $–body problem were constructed. We prove the existence of a continuous symmetric family of solutions of the restricted hip-hop $ (2N+1) $-body problem for each family of symmetric and periodic hip-hop solutions of the primaries studied in [14]. The main tools for proving our results are the implicit function theorem and a compactness argument. In addition, we present some numerical periodic solutions to the restricted $ 7 $-body problem. [ABSTRACT FROM AUTHOR]

This article discusses the incorporation of COVID-19-related content into physics exams for Introductory Physics for the Life Sciences (IPLS) courses. The authors provide sample exam questions that cover topics such as scaling, diffusion, and electricity, and discuss students' performance on these questions. The questions aim to demonstrate the relevance of physics to the COVID-19 pandemic and help students understand real-life applications of physics principles. The authors also provide additional resources, such as Physics Activities for the Life Sciences (PALS), to assist instructors in teaching physics to IPLS students. [Extracted from the article]

With the planning of new ambitious gravitational wave observatories, fully controlled laboratory experiments on dynamic gravitation become more and more important. Such experiments can provide new insights in potential dynamic effects such as gravitational shielding or energy flow and might contribute to bringing light into the mystery still surrounding gravity. Here we present a laboratory-based transmitter-detector experiment using two rotating bars as transmitter and a 42 Hz, high-Q bending beam resonator as detector. Using a precise phase control to synchronize the rotating bars, a dynamic gravitational field emerges that excites the bending motion with amplitudes up to 100 nm/s or 370 pm, which is a factor of 500 above the thermal noise. The two-bar design enables the investigation of different transmitter configurations. The detector movement is measured optically, using three commercial interferometers. Acoustical, mechanical, and electrical isolation, a temperature-stable environment, and lock-in detection are central elements of the setup. The moving load response of the detector is numerically calculated based on Newton's law of gravitation via discrete volume integration, showing excellent agreement between measurement and theory both in amplitude and phase. The near field gravitational energy transfer is 1025 times larger than the one of the propagating gravitational wave component. The ever-expanding field of gravitational wave science calls for controlled laboratory experiments on dynamic gravitation to provide insights and more precise measurements of gravity. The authors propose, model, and experimentally realize a system using two rotating bars as transmitter and a bending beam resonator as detector, finding that the near field gravitational energy transfer that creates detector amplitudes of up to 100 nm/s is 10 to the power of 25 times higher than what would be expected from gravitational waves emitted from an equivalent quadrupole gravitational wave generator. [ABSTRACT FROM AUTHOR]

Projection of future meteorological patterns such as median temperature and precipitation is necessary for governments to facilitate civil aviation, forecast agricultural productions, and advise public energy policies. Various models are proposed based on historical data, such as the short-term 7-day forecast or the long-term Global Forecast System, to study climate change. The main contribution of the paper is that it gives a feasible, cost-effective model for median-term projections with statistically tested accuracies well within the accepted margins of the scientific community. This model is the starting point to provide general guidelines to governments to forecast levels of energy consumption for residential cooling in summer and heating in winter to provide energy subsidies for low-income populations and for organizations supporting countries needing energy assistance. Additionally, midterm models are also useful during global energy disruptions. A theoretical model is derived based on orbital mechanics, planetary science, and astronomy using Newton's Law of Universal Gravitation and Kepler's Laws of Planetary Motions. The model is then optimized with historical data in a specific region. The model's predictions are then statistically compared with the actual observed temperature outside the training data. In sum, the current harmonic oscillator method can be beneficially utilized by governments to forecast natural phenomena in order to provide timely assistance to respective populations such as predicting extreme temperature fluctuations in the planning of agricultural productions. [ABSTRACT FROM AUTHOR]

Space gravity measurements have been mainly used to study the temporal mass variations at the Earth's surface and within the mantle. Nevertheless, mass variations due to the Earth's core might be observable in the gravity field variations as measured by Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On satellites. Earth's core dynamical processes inferred from geomagnetic field measurements are characterized by large‐scale patterns associated with low spherical harmonic degrees of the potential fields. To study these processes, the use of large spatial and inter‐annual temporal filters is needed. To access gravity variations related to the Earth's core, surface effects must be corrected, including hydrological, oceanic or atmospheric loading (Newtonian attraction and mass redistribution). However, these corrections for surface processes add errors to the estimates of the residual gravity field variations enclosing deep Earth's signals. As our goal is to evaluate the possibility to detect signals of core origin embedded in the residual gravity field variations, a quantification of the uncertainty associated with gravity field products and geophysical models used to minimize the surface process signatures is necessary. Here, we estimate the dispersion for GRACE solutions as about 0.34 cm of equivalent water height (EWH) or 20% of the total signal. Uncertainty for hydrological models is as large as 0.89–2.10 cm of EWH. We provide estimates of Earth's core signals whose amplitudes are compared with GRACE gravity field residuals and uncertainties. The results presented here underline how challenging is to get new information about the dynamics of the Earth's core via high‐resolution, high‐accuracy gravity data. Plain Language Summary: The motions of the Earth's fluid core are deduced from ground and satellite measurements of the geomagnetic field variations. Because the long‐term variations of the Earth's gravity field might be correlated to the Earth's magnetic field, new information about the Earth's fluid core and its density changes could be accessed with gravimetry. The observation of the core processes must be done at very large spatial scales, in which case it is necessary to use gravity data from satellites. However, variations in the Earth's gravity field are also created by heterogeneous superficial sources such as ocean and atmospheric currents, variations in water storage, etc. To recover a signature of the Earth's fluid core, we need first to remove all other known effects of larger amplitudes from satellite observations of the gravity field. Our study compares models of gravity variations for different sources in order to estimate their uncertainty. Such uncertainties are discussed in view of the expected amplitudes of signals originated from the core. Key Points: Deep Earth's processes occur at large spatial and inter‐annual temporal scalesTime‐lapse gravity satellite data are compared with geophysical models at scales of interestLarge uncertainties on satellite data and geophysical models conceal the gravity signals originated from the Earth's core [ABSTRACT FROM AUTHOR]

Background: Improving and maintaining the skin integrity and health are the most essential targets in long-term care. The aim of this study is to formulate a serum of retinyl palmitate (RP) and vitamin E (VE) as nanoemulsion (NE) for achieving healthy skin. Methods: The solubility of RP and VE was studied in different oils. The NEs were prepared using oil, water, and different surfactant-co-surfactant mixtures, and then the medicated nanoemulsion was prepared by addition of 0.5% RP and VE to the oil phase, and vitamin C as an antioxidant to the aqueous phase with different preservatives. The prepared NE was characterized in terms of particle size, charge, rheology, diffusion, and irritation to the skin. Results and conclusion: The data showed that the highest solubility of both RP and VE was in safflower oil. Tween 20, Ceteareth 20 with ethanol, PEG 200, and cremophor RH40. This combination was able to produce NE with good integrity and acceptable particle size. The prepared formulations gave particle size of 60–70 nm and showed Newtonian flow. Irritation tests on rats showed that the formula was safe to be applied on the skin with no signs of irritation up to 72 hours. A preliminary stability study at room temperature showed good stability up to 6 weeks. In conclusion, RP and VE could be formulated successfully as NE with good stability and physical characteristics. [ABSTRACT FROM AUTHOR]

We consider again stationary solutions to the spherically symmetric Einstein–Maxwell–Klein–Gordon system, commonly known as "charged boson stars", originally studied by Jetzer and Van Der Bij (Phys Lett B 227:341, 1989). We construct families of charged boson stars in the ground state, for different values of the charge parameter q, and different values of the central scalar field. Following Jetzer and Van Der Bij, one can define a critical value for the charge q = q c that corresponds to the value for which the Coulomb repulsion of the bosonic particles exactly cancels their newtonian gravitational attraction. We confirm the claim made by Pugliese et al. (Phys Rev D, 2013. https://doi.org/10.1103/physrevd.88.024053) that super-critical solutions exist for a limited range of charges above the critical value q > q c (though we find an even smaller range of q for which this is possible). Our analysis indicates, however, that all such super-critical solutions are gravitationally unbound, and are therefore expected to be unstable. One of the main results of our analysis is the fact that, even though we do find a family of slightly super-critical solutions in the sense that q > q c , there are no super-critical solutions in the sense that the total charge Q is larger than the total mass M of the system. [ABSTRACT FROM AUTHOR]

Students are then asked: How much weaker is the force of gravity the astronauts in the ISS experience than someone on the surface of Earth? After calculating the gravitational force in both situations (on Earth and in the ISS), students can divide the smaller, weaker force (for those in orbit) by the bigger, stronger force (for those on the surface). The student can simply maintain the idea that astronauts float because of a weaker force of gravity due perhaps (in their mind) to the great distance of the ISS from Earth. Students need to get to the idea that they can calculate the gravitational force between Earth and the astronaut when the astronaut is on Earth and when the astronaut is in the ISS. [Extracted from the article]