arXiv subjects

Allan Walstad

Publications and source records attributed to Allan Walstad.

6 recordsLinked to original sources

arXiv2026

Moving Magnetic Flux and Electromagnetic Induction

Magnetic flux can move, and moving magnetic flux is associated with induced electric fields. Where there are multiple sources of flux, the induced electric field is the vector resultant of the induced fields attributable to the fluxes acting individually; it is not necessarily associated with the resultant magnetic field. The key insight is that flux can move through regions in which the magnetic field itself vanishes, much as electric charge can move (as electric current) through a region in which the net charge density is zero. For this reason, moving flux can account for the induced emf around a long solenoid in which the current is changing. It also accounts for unipolar induction, and this account is testable.

physics.gen-ph↗

arXiv2017

Time dilation and length contraction without relativity: The Bohr atom and the semi-classical hydrogen molecule ion

Recently it was shown that classical "relativistic" particle dynamics was implicit in physics going back to Maxwell. The demonstration utilized a simple modification of a 1906 thought experiment by which Einstein established the mass equivalence of energy, independently of the relativity postulates. The modified thought experiment leads directly to correct expressions for the momentum and kinetic energy of a particle at high speed. In the present paper, one additional ingredient is added, namely, the Bohr quantization rule of the old quantum theory. It is found that a semi-classical model of a hydrogen atom and a hydrogen molecule ion exhibit, respectively, time dilation and length contraction.

physics.hist-ph↗

arXiv2016

A Critical Reexamination of the Electrostatic Aharonov-Bohm Effect

This paper undertakes a critical reexamination of the electrostatic version of the Aharonov-Bohm ("AB") effect. The conclusions are as follows: 1. Aharonov and Bohm's 1959 exposition is invalid because it does not consider the wavefunction of the entire system, including the source of electrostatic potential. 2. As originally proposed, the electrostatic AB effect does not exist. Perhaps surprisingly, this conclusion holds despite the relativistic covariance of the electromagnetic four-potential combined with the well-established magnetic AB effect. 3. Although the authors attempted, in a 1961 paper, to demonstrate that consideration of the entire system would not change their result, they inadvertently assumed the desired outcome in their analysis. 4. Claimed observations of the electrostatic AB effect or an analogue thereof are shown to be mistaken.

quant-ph↗

arXiv2016

Further Considerations Regarding the Aharonov-Bohm Effect and the Wavefunction of the Entire System

In an earlier paper it was demonstrated that the hypothesized electrostatic version of the Aharonov-Bohm ("AB") effect does not exist. The conclusion follows straightforwardly once one recognizes that interference takes place in the configuration space of the entire system, including the experimental apparatus, and the wavefunction of the apparatus cannot be ignored. Two additional results are presented here. 1. Observations of interference that had been attributed to an analogue of the electrostatic AB effect (or "scalar effect") are actually due to a magnetic AB effect. 2. In the original magnetic AB effect itself, there is no phase shift if it is possible effectively to shield the solenoid from the influence of the passing electron. This result is not in conflict with the landmark experiments of Tonomura and colleagues if Wang's recent claim is correct, that superconductive shielding could not have isolated the toroidal magnet from the magnetic pulse of the passing electron.

quant-ph↗

arXiv2015

"Relativistic" particle dynamics without relativity

It is shown that the correct expressions for momentum and kinetic energy of a particle moving at high speed were already implicit in physics going back to Maxwell. The demonstration begins with a thought experiment of Einstein by which he derived the inertial equivalence of energy, independently of the relativity postulates. A simple modification of the same experiment does the rest.

physics.hist-ph↗

arXiv2015

Quantum Dynamical Relativity and the Nature of Spacetime

Einstein's special theory of relativity starts with assumptions about how observations conducted in relatively moving inertial frames must compare. From these assumptions, conclusions can be drawn regarding the laws of physics in any one frame. Can we do the reverse, that is, build the correct physics entirely from considerations within a single frame and infer therefrom the results of measurements in moving frames? Can we, in this project, supply the "elementary foundations" that Einstein found lacking in his own theory, thereby converting special relativity from (in Einstein's terminology) a "principle" theory to a "constructive" one? Expanding on the approach suggested by Johns S. Bell, this paper demonstrates that we can progress toward those goals via the introduction of elementary quantum concepts, particularly the idea of matter waves (deBroglie waves) that was unknown to Einstein in 1905. This quantum dynamical approach offers to resolve a recent dispute in philosophy of physics regarding the Minkowski geometry of spacetime.

physics.hist-ph↗