Dynamics of Gliding Arc Climbing in a Unipolar Jacob’s Ladder

Technical Physics - We have designed a device with a gliding unipolar arc of the Jacob’s ladder type. The dynamics of arc rising has been investigated. It is found that the arc climbs at a...     

What’s new at small x?

We discuss some recent developments in small x physics.     

Purcell’s “rotator”: mechanical rotation at low Reynolds number

An object consisting of three spheres, linked like the spokes on a wheel, can undergo a net rotational movement when the relative positions of the spheres proceed through a four-step cycle. This rotational motion is the analogue of the two-hinged swimmer originally proposed by Purcell (1977), which has served as a prototype for mechanical implementations of swimming. We also note that the rotational motion analysed here may be useful in the design of micromachines and has similarities to molecular-scale rotational motors that have been identified recently.     

Bell’s theorem with no locality assumption: putting free will at work

We prove a version of Bell’s Theorem which does not assume Locality but instead only the conjunction of a Free Will Principle (so weak that one’s will needs not be free from one’s past) and what we call the Effect After Cause Principle (EACP) according to which for any Lorentz observer the value of an observable measured at (x ₀ , t ₀) cannot further change to another value at (x ₀ , t ₀) because of any cause which happens after said observable has been measured at (x ₀ , t ₀) for that observer, with a similar condition on variables which depend on Realism. Since the EACP, which does not forbid all forms of dependance upon future effects, is compatible both with Locality and with Non-Locality, Locality cannot be considered as the common cause of all the contradictions obtained in all versions of Bell’s Theory. By the very nature of what is a Bell’s Inequality, all versions of Bell’s Theorem assume Weak Realism according to which the value of an observable needed in the discussion of Bell’s Theorem is well defined whenever the measurement could have been made and some measurement is made. This work supports the view that it is Weak Realism, not Locality, which needs to be negated to avoid the contradictions in microscopic Physics associated to Bell’s Theory, at least if one refuses as false the de Broglie-Bohm Hidden Variable theory, e.g., because of its essential violation not only of Locality but also of Lorentz invariance.     

Winterberg’s Conjectured Breaking of the Superluminal Quantum Correlations over Large Distances

We elaborate further on a hypothesis by Winterberg that turbulent fluctuations of the zero point field may lead to a breakdown of the superluminal quantum correlations over very large distances. A phenomenological model that was proposed by Winterberg to estimate the transition scale of the conjectured breakdown, does not lead to a distance that is large enough to be agreeable with recent experiments. We consider, but rule out, the possibility of a steeper slope in the energy spectrum of the turbulent fluctuations, due to compressibility, as a possible mechanism that may lead to an increased lower-bound for the transition scale. Instead, we argue that Winterberg overestimated the intensity of the ZPF turbulent fluctuations. We calculate a very generous corrected lower bound for the transition distance which is consistent with current experiments.     

Interatomic potentials at short range using Madelung’s equations

Interatomic potentials at short range are investigated starting from the united atom electron density. Prior work has utilised time independent Rayleigh-Schr?dinger perturbation theory, adapted to overcome difficulties with convergence of the power series in internuclear distance, and has been confined to diatomic species. This work presents a time dependent approach, based on Madelung’s equations, in which the electron density evolves continuously from that of the united atom to the density of the polyatomic system; no power series is involved, there are no convergence difficulties and the approach is applicable to polyatomic systems. Electronic separation and interaction energies are calculated and compared to previous calculations. Some triatomic and tetratomic arrays of hydrogen atoms are examined and three and four body interaction terms estimated.     

First-Order Phase Transformation at Constant Volume: A Continuous Transition?

We describe a first-order phase transition of a simple system in a process where the volume is kept constant. We show that, unlike what happens when the pressure is constant, (i) the transformation extends over a finite temperature (and pressure) range, (ii) each and every extensive potential (internal energy U, enthalpy H, Helmholtz energy F, and Gibbs energy G), and the entropy S is continuous across the transition, and (iii) the constant-volume heat capacity does not diverge during the transition and only exhibits discrete jumps. These non-intuitive results highlight the importance of controlling the correct variables in order to distinguish between continuous and discontinuous transitions. We apply our results to describe the transition between ice VI and liquid water using thermodynamic information available in the literature and also to show that a first-order phase transition driven in isochoric condition can be used as the operating principle of a mechanical actuator.     

Observational Aspects of Magnetic Reconnection at the Earth’s Magnetosphere

Magnetic field reconnection has shown to be the dominant process in the solar wind-Earth’s magnetosphere interaction. It enables mass, momentum, and energy exchange between different plasma regimes, and it is regarded as an efficient plasma acceleration and heating mechanism. Reconnection has been observed to occur in laboratory plasmas, at planetary magnetospheres in our Solar System, and the Sun. In this work, we focus on analyzing the characteristics of magnetic reconnection at the Earth’s magnetosphere according to spaceborne observations in the vicinity of our planet. Firstly, the locations where magnetic field reconnection are expected to occur within the vast magnetospheric region are addressed, and is shown how they are influenced by changes in the interplanetary magnetic field direction. The main magnetic field and plasma signatures of magnetic reconnection are discussed from both theoretical and observational points of view. Spacecraft observations of ion inertial length scale reconnection are also presented.     

Blowup of Jang’s Equation at Outermost Marginally Trapped Surfaces

The aim of this paper is to accurately describe the blowup of Jang’s equation. First, we discuss how to construct solutions that blow up at an outermost MOTS. Second, we exclude the possibility that there are extra blowup surfaces in data sets with non-positive mean curvature. Then we investigate the rate of convergence of the blowup to a cylinder near a strictly stable MOTS and show exponential convergence with an identifiable rate near a strictly stable MOTS.     

Investigation of primary cosmic rays at the Moon’s surface

The possibility of experimentally studying primary cosmic rays at the Moon’s surface is considered. A mathematical simulations of showers initiated in the lunar regolith by high-energy particles of primary cosmic rays is performed. It is shown that such particles can in principle be recorded by simultaneously detecting three components of backscattered radiation (secondary neutrons, gamma rays, and radio emission).     

Recognizing pedestrian’s unsafe behaviors in far-infrared imagery at night

Pedestrian behavior recognition is important work for early accident prevention in advanced driver assistance system (ADAS). In particular, because most pedestrian-vehicle crashes are occurred from late of night to early of dawn, our study focus on recognizing unsafe behavior of pedestrians using thermal image captured from moving vehicle at night. For recognizing unsafe behavior, this study uses convolutional neural network (CNN) which shows high quality of recognition performance. However, because traditional CNN requires the very expensive training time and memory, we design the light CNN consisted of two convolutional layers and two subsampling layers for real-time processing of vehicle applications. In addition, we combine light CNN with boosted random forest (Boosted RF) classifier so that the output of CNN is not fully connected with the classifier but randomly connected with Boosted random forest. We named this CNN as randomly connected CNN (RC-CNN). The proposed method was successfully applied to the pedestrian unsafe behavior (PUB) dataset captured from far-infrared camera at night and its behavior recognition accuracy is confirmed to be higher than that of some algorithms related to CNNs, with a shorter processing time.     

Quantum Humor: The Playful Side of Physics at Bohr’s Institute for Theoretical Physics

From the 1930s to the 1950s, a period of pivotal developments in quantum, nuclear, and particle physics, physicists at Niels Bohr??s Institute for Theoretical Physics in Copenhagen took time off from their research to write humorous articles, letters, and other works. Best known is the Blegdamsvej Faust, performed in April 1932 at the close of one of the Institute??s annual conferences. I also focus on the Journal of Jocular Physics, a humorous tribute to Bohr published on the occasions of his 50^th, 60^th, and 70^th birthdays in 1935, 1945, and 1955. Contributors included Léon Rosenfeld, Victor Weisskopf, George Gamow, Oskar Klein, and Hendrik Casimir. I examine their contributions along with letters and other writings to show that they offer a window into some issues in physics at the time, such as the interpretation of complementarity and the nature of the neutrino, as well as the politics of the period.     

Precise laser spectroscopy of antiprotonic helium at CERN’s Antiproton Decelerator

The ASACUSA collaboration of CERN has carried out several laser spectroscopy experiments of antiprotonic helium atoms. By comparing the results with three-body QED calculations, the antiproton-to-electron mass ratio was determined as $M_{\overline{p}}/m_e=1836.152674(5)$ . We are now developing some laser systems and detectors to further improve the experimental precision.     

Elastic Properties of Graphene-Like Compounds: the Keating’s and Harisson’s Models

Physics of the Solid State - The third-order elastic constants, the pressure dependences of the second-order elastic constants, the Kleinman and Grüneisen parameters, and the thermal expansion...