arXiv subjects

D. F. Roscoe

Publications and source records attributed to D. F. Roscoe.

3 recordsLinked to original sources

arXiv2022

MOND: A consequence of the geometric Leibniz Clock

Leibniz considered the notion of the 'empty physical space' to be a meaningless abstraction, and he held firmly to the view that the only significant thing was the set of relationships between 'objects', whatever these 'objects' might be. Similarly, he was equally clear in expressing his views about Newton's universal time, which he also considered to be a meaningless abstraction. In effect, for him, time was no more than a synonym for ordered change within a material system. The process of giving quantitative realization to this duality of non-Newtonian ideas forms the core of this work. A primary result arising is that every gravitating particle is no more than a clock - the geometric Leibniz Clock - which provides all the basic things: it conserves energy and angular momentum and satisfies the Weak Equivalence Principle. When the Clock is applied to model the concept of a galactic object within which all motions are circular, the characteristic properties of the MOND galaxy (asymptotic flatness, a critical acceleration scale, the baryonic Tully-Fisher relationship) are quantitatively reproduced in the resulting Leibniz galaxy. In short, the characteristic essence of MOND has its source in the geometric Leibniz Clock.

astro-ph↗

arXiv2009

The conflict between realism and the scalar potential in electrodynamics

Within no inertial frame can stationary charge exist. All charge, wherever it exists, experiences perpetual interaction with charge elsewhere and so can only exist as non-trivial current. It follows that the notion of the electrostatic scalar potential is a pragmatic idealization - it is not fundamental and is useful simply because, in many practical circumstances, the time scales of interest are sufficiently small that charges can be considered stationary in appropriately chosen inertial frames. In this paper, we take the view that the subsuming of the electrostatic scalar potential within classical electrodynamics raises issues of fundamental principle and consider the question of whether it is possible to have a relativistic electrodynamics sans the electrostatic scalar potential - that is, expressed purely in terms of some form of relativistic magnetic potential. Surprisingly, we find that such a thing can be realized in a remarkably simple way - and which is cost-free for ordinary applications of electrodynamics. But the overall formalism has fundamental ramifications for our deeper understanding of electrodynamics - for example, a new relativistic symmetry arises which, naturally interpreted, implies that the Lorentz force must be considered as a local-action contact force in which energy-momentum is locally conserved through the medium of an uncharged massive vector particle.

math-ph↗

arXiv2002

Discrete dynamical classes for galaxy discs and the implication of a second generation of Tully-Fisher methods

We consider the four large optical rotation curve samples of Mathewson, Ford & Buchhorn (900 ORCs), Mathewson & Ford (1200 ORCs), Dale, Giovanelli, Haynes et al (494 ORCs) and Courteau (300 ORCs). We show how it is possible to partition any given ORC into two distinct dynamical regions - an interior region and an exterior region. Each of the samples considered is partitioned in this way, so that we are able to consider the dynamics on the exterior parts of the ORCs for each of the samples. This technique was originaly introduced by Roscoe astro-ph/0107305. We then find that the dynamics in the exterior part of spiral discs fall into one of four sharply defined classes. Taking account of the various correlations which exist between luminosity properties and dynamical properties of discs, our final phenomonological conclusion is that spiral discs in the samples considered appear constrained to occupy one of four distinct planes, F(M,S,a) = k0, k1, k2, k3, where M = absolute magnitude, S = surface brightness, "a" is a parameter computed directly from each ORC and k0, k1, k2, k3 are well defined numerical constants. These results are statistically supported at the level of virtual certainty. We suggest three possible mechanisms for this phenomonology. The overall analysis implies the existence of a second generation of Tully-Fisher methods in which the standard TF relation is augmented with a second relation defining where on an ORC the linewidth should be measured.

astro-ph↗