Macroscopic Physics Research Articles

Stress-strain fluctuations in non-linear hydrodynamics

Two different formulations of hydrodynamic fluctuations in the non-linear regime have been proposed. One of these involves a stress-strain fluctuation term of multiplicative type, and consequently this formulation was criticized by Fox three years ago. Recently, Saarloos, Bedeaux and Mazur have proposed such a formulation again, and have criticized Fox's original criticism. In the present paper, it is again shown that multiplicative stress-strain fluctuations lead to unphysical divergences, and that Saarloos, Bedeaux and Mazur have failed to observe that a stochastic quantity, x, may have zero mean, =0, but a divergent second moment 〈(x)2〉=∞. In addition, they have failed to note the limitations of time reversal invariance arguments in macroscopic physics, and they have overlooked important distinctions regarding transverse and longitudinal modes in hydrodynamics. These issues are elucidated in this paper.

Electric, Optic and Acoustic Interactions in Dielectrics

Donald F Nelson 1979 Chichester: John Wiley xiv + 539 pp price £20.95 Classical treatments of the macroscopic physics of dielectrics have developed historically in a sensibly independent manner. A wealth of literature exists dealing with the elastic, piezoelectric, optical and electromagnetic properties of dielectric materials and, in particular, with the all–important aspects of anisotropy, which are what make so many of the interesting crystalline properties possible.

General Relativity from A to B

Robert Geroch 1978 London: University of Chicago Press xi + 225 pp price £8.40 The main aim of Dixon's book is to show that it is by no means true that special relativity is irrelevant to the macroscopic physics of ordinary material systems under terrestrial conditions. In a clear and lucid text the author shows that, by unifying dynamics, thermodynamics and electromagnetism into a coherent whole, special relativity gives a deeper appreciation of each of these topics.

Metagesetze und theorieunabhängige Bedeutung physikalischer Begriffe

The determination of the meaning of theoretical terms by the axioms of theories as meaning postulates and the merely fictitious character of a basic observational language leads to Feyerabends problem of the incommensurability of physical theories. Different theories are actually compared by physicists as well. They might have a common sublanguage as the language of macroscopic physics in atomic physics. Furthermore shared metalaws (e. g. invariance principles) define an equivalence relation which identifies terms of different theories and enables physicists to talk about them in a common language.

A causal explanation for quantum phenomena in macroscopic physics

The dynamics underlying quantum theory for macroscopic physics is based on the topology of flows on a cusp catastrophe obtained by the minimization of a potential function. By this relation at a known potential energy, a causal explanation of the quantum effect is provided.

Smorn-II summary an overview and a gaze into the future

A logic scheme of application of the Bartlett formalism is introduced. State transitions caused by the different subprocesses, chosen for the simulation of the overall process, are described by this original formalism, once the assumption is made that the ensemble of the subprocesses under study can be thought as a global Markov process. In his book M.S. Bartlett states that “the appropriate equation for many Markov chains can be written down at once in terms of the possible transitions” without going through the tedious time-consuming and error-prone routine involving the detailed probability balance principle. A partial time differential equation is thus obtained. The form of this equation features striking analogies with similar equations met in macroscopic and microscopic statistical physics. The circumstance suggests investigations in joint ventures of interdisciplinary groups.

The elementary acoustical signal explained as a quantum phenomenon of macroscopic physics resulting from the minimization of a potential function

The boundary conditions for the minimum elementary signal defined: f0 t0 = ΔfΔt= 1/2 (where f0 is signal midfrequency, t0 is signal midperiod. Δf is signal bandwidth, and Δt is signal duration) also describe the topologically defined condition known as either (i) a critical point, (ii) a singularity in mapping one manifold into another, (iii) a local potential fluctuation, or (iv) a flow on a cusp catastrophe. An elementary signal, or any quantum, is a limit cycle or oscillation hysteresis defined within an area of instability of a precisely defined mapping plane. The collection of unstable maps of the potential function, from which the elementary signal is derived, defines those instances in which quantum theory is applicable. Thus, a wave event cannot become infinitely small and still be meaningful, i.e., informationally relevant. This result provides an explanation for parametric excitation, as well as a tool for the study of cochlear fluid mechanics.

Geometry and physics of the microcosmos

In this article a critical analysis is given of basic geometric concepts as applied to the physics of the microcosmos. The article begins with an outline of geometry in macroscopic physics. This part is based on the classical papers of H. Poincare, A. Einstein, and A. A. Fridman. An indication of possible limitations on the concept of a point event associated with limiting densities of matter represents new material. Subsequently localization of elementary particles is discussed and limits of possible accuracy are indicated. In the article it is emphasized that the logical structure of local quantum field theory presupposes the existence of particles of arbitrarily large mass. The existence of maximons–particles of a limiting, but finite mass–strong gravitation (collapse of particles), instability of particles with respect to decay due to the weak interaction (this interaction can become strong for very heavy particles and can lead to lead to total instability of such a particle). In the conclusion of the article two features of a nonlocal field theory are considered. In this theory the coordinates of a point event are operators, while momentum space remains a numerical space (either curved or flat). The first variant presupposes commutation conditions for the coordinates of a point (the Snyder-Kadyshevskii theory), while the second variant presupposes anticommutation conditions (the author's theory).

On linearized hydrodynamic modes in statistical physics

We formulate the linearized generalized Boltzmann equation as an (asymmetric) eigenvalue problem. This problem has five eigenvalues which tend to zero when the uniformity parameter tends to zero: to second order in this parameter, they correspond to damped sound (two modes), diffusing shear flow (two modes), and diffusing entropy flow (one mode). The microscopic expressions deduced from these results for the transport coefficients agree with the correlation-function formulas. Moreover, the corresponding eigenfunctions are explicitly displayed to lowest order in the uniformity parameter: they are microscopic analogs, in terms ofone-particle distribution functions, of the well-known linearized hydrodynamic modes of macroscopic physics. All results are established to all orders in the interactions.

Solution of the electrohydrostatic boundary equations and application to the sessile drop

This paper is a sequel to a previous one (containing an error which is corrected) in which the general hydrostatics of an electrically conducting liquid under an electrostatic field was treated, taking into account the electric double layer, the theory being considered as rigorous within the framework of macroscopic physics. In that paper a set of equations was obtained governing the shape of a liquid boundary. Two problems were solved in the first approximation, but no general method of solution was given and a procedure of guess-work was used at an important stage. In this paper a general method is given with forms pertaining to axisymmetric two- and three-dimensional situations, respectively, and it is applied to find the second approximation to the solution of one of the previous problems, that of the two-dimensional sessile drop. The treatment of this problem involves the solution of an interesting electrostatic problem and the tabulation of a function.

Causality in present-day field theory

The form of causality used in present-day theory follows from basic space-time concepts. It has been borrowed from macroscopic physics and, in view of the nature of the singularities in the Green's functions, it is carried over automatically to infinitely small scales. This leads to divergencies (infinities) in a number of the more important physical quantities associated with elementary particles. In this paper we have discussed some of the preliminary theoretical schemes which, while retaining macroscopic causality, produce substantial changes in causality for small space-time scales.

Macroscopic Physics of Surface Recombination in Semiconductors†

ABSTRACT It is shown that the concept of surf ace recombination velocity commonly used to describe surface properties of transistor materials, is only valid when its magnitude is small compared with the diffusion velocity. An improved model in which the excess charge carrier lifetime is supposed to vary with position is analysed, and it is found that the- apparent recombination velocity can depend markedly on the experimental conditions when the diffusion length is short as with indium antimonide. It is also found that the common method of measuring this velocity with thin slice material is not valid when the effect is too large. A brief inspection of the possible influence of electric field shows that it could dominate in determining the magnitude of the velocity.

Proceedings of the Physical Society : Sections A and B

ONE of tha main reasons for dividing the Proceedings of the Physical Society into two sections A and B wae to give the advantage of an increased volume of publication without burdening the Fellows with a further compulsory increase in subscription; this would have been inevitable had an enlarged Proceedings been distributed to all the Fellows. In the light of experience gained over the course of the past year, it has been found that the division which best meets the needs of Fellows is one which brings papers on microphysics and the physics of elementary particles into Section A, and papers on macroscopic physics into Section B. Cases arise where the division is bound to be somewhat arbitrary. While it is essential to maintain a certain amount of flexibility in the allocation of papers, a paper will, so far as possible, be put in the section where the main interest of the readers lies; for example, a paper on counter-technique would appear in? if the circuitry is the main interest, but would be in A if the applications to actual counting are of major importance. Details are available from the offices of the Physical Society, 1 Lowther Gardens, Prince Consort Road, London, S.W.7.

Experiment and Theory in Physics

THE question of the relation between theory and experiment in physics is one of perennial interest. It is, of course, only one aspect of the fundamental philosophical problem of the general relation of the rational to the empirical, and it is not too much to say that the peculiar character of progress in physics during the last generation has made it, for the time at any rate, the most important aspect of that problem. Certainly no one can contemplate the development during this century of both macroscopic and microscopic physics—relativity and quantum theory—without realizing that, whether or not his philosophical outlook has been modified thereby, its most appropriate expression must be very different from any which was possible previously. Experiment and Theory in Physics By Prof. Max Born. Pp. iv + 44. (Cambridge: At the University Press, 1943.) 2s. net.

Physics in the Making

FRANKLY, we find the title of Prof. Newman's new book a little puzzling. He sets out to deal with recent advances in non-atomic physics, and, knowing his flair for exposition, we looked forward to a readable account, with due emphasis given to the experimental side, of recent developments in what we might call macroscopic or molar physics. His account is readable enough, and interesting experimental detail bulks largely therein, but the choice of topics bears singularly small relation to the title. Wave mechanics; statistical mechanics; electromagnetic radiation, including a discussion of infra-red spectra; γ-rays, cosmic rays, and the scattering and diffraction of X-rays; ninety pages on modern magnetics, and, under the heading electricity, a discussion, inter alia, of electrolytic conduction and of super-conductivity. These be strange themes to meet in a work where we had hoped a comfortable certainty would reign supreme and electron waves would cease to surge and roar. Recent Advances in Physics (Non-Atomic). By Prof. F. H. Newman. Pp. ix + 378. (London: J. and A. Churchill, 1932.) 15s.

The charge of an electron

1. It is well known that the ratio of hc to e 2 is a pure number. The methods of macroscopic physics break up the number and scatter its factors, so that it strikes us as an artificial construction and its dimensionless character seems an irrelevant curiosity. But in the wave-theory of the interaction of electrons the number is kept intact. Since electric charge is only manifested in the interaction of at least two charges it is useless to consider a solitary electron. The most elementary appearance of e in physics is in the wave-equation for two electrons (or an electron and proton); it there occurs in the combination hc /2π e 2 as the coefficient of certain terms. The experimental value of hc /2π e 2 is 137∙1 (Millikan’s data). According to the theory proposed in this paper it should be the integer 136. Although the discrepancy is about three times the probable error attributed to the experimental value, I cannot persuade myself that the fault lies with the theory. The basis of my argument is the Exclusion Principle in the form given by Fermi and Dirac, viz., that the ψ functions pertaining to a pair of electrons must be antisymmetrical. Combined with the theory of relativity, this appears to lead in an unforced manner to the value 136, viz., the number of symmetrical terms in an array of 16 rows and columns.