Penetration of Waves and Particles through Porous Structures

The penetration of quantum and classical charged particles through porous films is investigated. The passage of quantum particles is analyzed by numerically solving the Schrödinger equation. The force of polarization acting on a charge is calculated by means of classical electrodynamics. The possibility of perforating thin films is analyzed.     

Maxwell electromagnetic theory,Planck's radiation law,and Bose—Einstein statistics

We give an example in which it is possible to understand quantum statistics using classical concepts. This is done by studying the interaction of chargedmatter oscillators with the thermal and zeropoint electromagnetic fields characteristic of quantum electrodynamics and classical stochastic electrodynamics. Planck's formula for the spectral distribution and the elements of energy hw are interpreted without resorting to discontinuities. We also show the aspects in which our model calculation complement other derivations of blackbody radiation spectrum without quantum assumptions.     

Dimensions and units in electrodynamics

We sketch the foundations of classical electrodynamics, in particular the transition that took place when Einstein, in 1915, succeeded to formulate general relativity. In 1916 Einstein demonstrated that, with a choice of suitable variables for the electromagnetic field, it is possible to put Maxwells equation into a form that is covariant under general coordinate transformations. This unfolded, by basic contributions of Kottler, Cartan, van Dantzig, Schouten & Dorgelo, Toupin & Truesdell, and Post, to what one may call premetric classical electrodynamics. This framework will be described shortly. An analysis is given of the physical dimensions involved in electrodynamics and subsequently the question of units addressed. It will be pointed out that these results are untouched by the generalization of classical to quantum electrodynamics (QED). We compare critically our results with those of L.B. Okun which he had presented at a recent conference.     

Method of semiclassical representation in quantum electrodynamics

The operators of the classical amplitudes of an electromagnetic field are introduced and a method of transferring from quantum electrodynamics to the semiclassical approximation both in the case of a free field and in the case of the interaction of the field with a quantum system is given. The method considered enables one to set up solutions of quantum electrodynamics in the case of an intense field from the solutions of the semiclassical problem. An operator method of obtaining solutions of the equations of semiclassical electrodynamics is considered. The physical meaning of the quantum corrections to the semiclassical electrodynamics of an intense field is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 77–98, February, 1980.     

Hydrogen atom spectrum and the lamb shift in noncommutative QED

We have calculated the energy levels of the hydrogen atom as well as the Lamb shift within the noncommutative quantum electrodynamics theory. The results show deviations from the usual QED both on the classical and the quantum levels. On both levels, the deviations depend on the parameter of space/space noncommutativity.     

In Appreciation Julian Schwinger: From Nuclear Physics and Quantum Electrodynamics to Source Theory and Beyond

Julian Schwinger’s influence on twentieth-century science is profound and pervasive. He is most famous for his renormalization theory of quantum electrodynamics, for which he shared the Nobel Prize in Physics for 1965 with Richard Feynman and Sin-itiro Tomonaga. This triumph undoubtedly was his most heroic work, but his legacy lives on chiefly through subtle and elegant work in classical electrodynamics, quantum variational principles, proper-time methods, quantum anomalies, dynamical mass generation, partial symmetry, and much more. Starting as just a boy, he rapidly became one of the preeminent nuclear physicists in the world in the late 1930s, led the theoretical development of radar technology at the Massachusetts Institute of Technology during World War II, and soon after the war conquered quantum electrodynamics, becoming the leading quantum-field theorist for two decades, before taking a more iconoclastic route during the last quarter century of his life.     

Quantum theory: The classical theory of nonlinear electromagnetics

This paper combines a classical electrodynamic base, adaptive electrons, and reactive radiation reaction energy effects and obtaines atomic stability, the Schrödinger equation, and quantized radiation. Electrons are assigned intrinsic parameter values and modeled as dynamic distributions of charge and current densities, bound together in a soliton-like way, with a form that alters in response to local force fields: not as waves or rigid spheres. The result is a deterministic view of quantum theory. Its postulatory base is replaced with derived results. The statistical interpretation of the wave function is that of standard quantum mechanics. When combined with classical electrodynamics, the theory completely describes quantum radiation.     

Particles and events in classical off-shell electrodynamics

Despite the many successes of the relativistic quantum theory developed by Horwitz et al., certain difficulties persist in the associated covariant classical mechanics. In this paper, we explore these difficulties through an examination of the classical. Coulomb problem in the framework of off-shell electrodynamics. As the local gauge theory of a covariant quantum mechanics with evolution paratmeter τ, off-shell electrodynamics constitutes a dynamical theory of ppacetime events, interacting through five τ-dependent pre-Maxwell potentials. We present a straightforward solution of the classical equations of motion, for a test event traversing the field induced by a “fixed” event (an event moving uniformly along the time axis at a fixed point in space). This solution is seen to be unsatisfactory, and reveals the essential difficulties in the formalism at the classical levels. We then offer a new model of the particle current—as a certain distribution of the event currents on the worldline—which eliminates these difficulties and permits comparison of classisical off-shell electrodynamics with the standard Maxwell theory. In this model, the “fixed” event induces a Yukawa-type potential, permitting a semiclassical identification of the pre-Maxwell time scale λ with the inverse mass of the intervening photon. Numerical solutions to the equations of motion are compared with the standard Maxwell solutions, and are seen to coincide when λ≳10⁻⁶ seconds, providing an initial estimate of this parameter. It is also demonstrated that the proposed model provides a natural interpretation for the photon mass cut-off required for the renormalizability of the off-shell quantum electrodynamics.     

Interferences,ghost images and other quantum correlations according to stochastic optics

There are an extensive variety of experiments in quantum optics that emphasize the non-local character of the coincidence measurements recorded by spatially separated photocounters. These are the cases of ghost image and other interference experiments based on correlated photons produced in, for instance, the process of parametric down-conversion or photon cascades. We propose to analyse some of these correlations in the light of stochastic optics, a local formalism based on classical electrodynamics with added background fluctuations that simulate the vacuum field of quantum electrodynamics, and raise the following question: can these experiments be used to distinguish between quantum entanglement and classical correlations?     

Quantum radiation by electrons in lasers and the Unruh effect

In addition to the Larmor radiation known from classical electrodynamics, electrons in a laser field may emit pairs of entangled photons – which is a pure quantum effect. We investigate this quantum effect and discuss why it is suppressed in comparison with the classical Larmor radiation (which is just Thomson backscattering of the laser photons). Further, we provide an intuitive explanation of this process (in a simplified setting) in terms of the Unruh effect.     

Quantum electrodynamic perturbation theory based on electrodynamics with an external field

A method is proposed for construction of mean values of quantum quantities in quantum optics and electrodynamics on the basis of exact solutions of the corresponding problems of electrodynamics with an external field. To illustrate the method the mean energy of a two-level atom in the Raby problem is calculated. It is shown that the mean value obtained with a specified accuracy coincides with the result of exact quantum electrodynamic calculation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 7–10, September, 1983.     

Spinor electrodynamics in terms of gauge-invariant quantities

We give a formulation of classical spinor electrodynamics in terms of gauge-invariant quantities. The set of invariants consists of bilinear combinations of spinor fields (currents), a real-valued covector field, and a complex scalar field of modulus one. The presented result is a first step towards formulating quantum electrodynamics in terms of gauge-invariant fields.     

Radiation reaction

I solve Maxwell's equation for a current produced by a classical, point electron. My solution, which represents the self electromagnetic field of the electron, can be found along the electron trajectory, where the conventional retarded-time solution is singular. The solution is in the form of an integral over all spectral frequencies of the field and has an Ehrenfest correspondence with the operator field of quantum electrodynamics (QED). Use of the field in the equation of motion for a harmonically-bound electron leads to an equation having the same form as the Schrödinger equation for a two-level atom interacting with the QED vacuum field.     

Correspondence principle in the self-energy problem

It has been shown by [2b.] that in the classical limit, , there is a correspondence between the quantum and classical electron self-energies in spinor electrodynamics. In the present work this result is extended to the cases of scalar electrodynamics and scalar meson theory. The apparent violation of the correspondence principle in the self-energy problem, noted in the literature, can be ascribed to the inadequacy of the usual expansion procedure in terms of the parameters and as (here Λ is the usual cutoff parameter, r₀ is the cutoff radius).     

Radiative reaction and quantum mechanics

According to the principles of quantum mechanics, the classical Lorentz-Dirac equations of the electron should follow from quantum electrodynamics in the classical limit. We show this is indeed true for the special case in which the charge does not radiate, provided the momentum operators in the Dirac theory are identified, in the classical limit, with the effective momenta of the Lorentz-Dirac equations.     

Remarks on the physical reality of gravitons

Rediscussing early arguments have led to the founding of quantum electrodynamics, but it is shown that one cannot employ them for the founding of quantum GRT. These arguments rather demonstrate that Einstein's GRT is essentially classical.