Abstracts Details

The growing interest in a thorough revision of the tenets of classical electrodynamics compels the physics community to reconsider the dominating magnetic field rationale applied to electrodynamics since the time of Lorentz. The torque-production mechanism presently attributed to homopolar machines, which is based on Grassmann's force, has been definitively ruled out by recent crucial experimentation. Conversely, Ampere's force law, restating the Newtonian symmetry requirement for energy conversion, fully explains homopolar torque production.

We report some recent experiments on motional induction, performed on partially shielded circuits. Both electro and ponderomotive forces are unsensitive to magnetic shielding. Laplace and Lorentz local forces must be applied with considerable care when dealing with motional induction.

The growing interest in a thorough revision of the tenets of classical electrodynamics compels us to reconsider the torque-production mechanism presently applied to homopolar machines founded - indistinctively - on Ampere's or Grassmann's basis. Recent crucial experimentation definitely rules out the latter rationale for its physical inconsistency.

Recent definitive experimentation unveils on Newtonian basis- standard field theory limitations in explaining homopolar torque production.

The growing interest in a thorough revision of the tenets of classical electrodynamics compels us to reconsider the torque-production mechanism presently applied to homopolar machines founded "indistinctively" on Ampere or Grassmann?s basis. Recent crucial experimentation definitively rules out the latter rationale for its physical inconsistency.

The crucial character of relative motion and Ampeers force law in interpreting homopolar induction was pointed out in recent experimentation performed by us. H. Montgomery suggests the compatibility of that experimental results with Maxwell's field theory. With the purpose of elucidating the applicable rationale this article identifies three independent energy-conversion mechanisms definable within the basic homopolar-machine frame and, hinging on a specially developed finite-element software, introduces an Amperian analysis of associated electro-and ponderomotive effects.

The paper by H. Montgomery published in this issue, exhibits a curious mix between local action models (fields) and non local (action a distance) prospects. When dealing with the motor configuration (Section 4, figure 7), Montgomery makes use of the (Amperian) surface currents instead of the B-field itself. By analysing the case B (the probe anchored to the turntable in the singularity), he recognizes, according to Newton's third law, force cancellation between the probe and the rims of the singularity: the probe becomes unable to spin the magnet. Astonishingly, he adds: but the more distant parts of the magnet still produce a force on the probe These few words deserve caution since for a field theoretician the suitable tool for force calculations is Laplace's expression, dF = I dl x B, where B is the magnetic field in which the wire is immersed, but not the distant field. Conversely, the field model works when applied to the closing circuit wire, which (being in true contact with the B-field ) is the responsible for the observed counter-clockwise rotation. When dealing with the generator configuration (Section 3, figure 5), a similar sketch is offered by Montgomery. The first time derivative of the B-field can be detected in the laboratory, but not at points fixed on the turntable. In other words, on the probe (according to Montgomery, the seat of the induced emf) there will be ? B/ ? t = 0, as if the turntable were at rest in the laboratory.

Following our investigation on motional electromagnetic induction, we search for electromotive force (emf) generation in ?confined B-field? homopolar engines. Four independent experiments are here presented. The above experiments suggest the non local nature of motional induction.

Mikhailov claims to have measured changes in the electron's inertial mass when located inside a uniformly charged spherical shell. The above mass, calculated by Assis founded on Weber's force becomes m_{W} = m_{o} - qV/3c^{2} for a charge q placed in a region of Coulomb's potential V.

In page 161 of Mikhailov states: ?So, if q and V have same (opposite) signs there is a decrease (increase) of the particle's effective mass.? Then, for q = ?e and V = k(Q/R) > 0, we get a mass increase yielding m = m_{o} + eV/3c^{2} > m_{o}.

We remember now that also Einstein's mass-energy equivalence, m_{E} = Energy/c^{2}, allows us to predict the electron mass-electrostatic potential dependence, of the same order of magnitude but opposite in sign. As a matter of fact, we have described the electronic mass defect taking place in the atomic electron. Let us consider an electron inside a positively charged spherical shell of charge Q, radius R producing a potential V = k(Q/R) > 0. The mutual electrostatic potential energy is ?eV < 0, so that a positive work must be supplied to carry the electron to infinite.

Hence the production of an induced current requires a relative motion of the disk and the external circuit, and not as one might expect a relative motion of the disk and the magnet," H. Montgomery wrote recently in the European Journal of Physics, adding, on page 180: "According to this argument there seems to be no justification for shifting the "seat" of the EMF to the external circuit when one considers Faraday's second experiment."

The first sentence above "true but physically "colourless" and the second deserve thorough consideration in light of recent experimental search advanced in Apeiron and widely published subsequently. In fact, since 2001 we have known that a spinning magnet induces a Lorentz-type electric field responsible for a motional Hall effect in the bulk of nearby conductors (Figure 1).

This article discusses experiments which enable the identification of the seat of mechanical forces in homopolar-machines reported earlier in this journal [J. Guala-Valverde and P. Mazzoni, Am. J. Phys. 63, 228-229 (1995); J. Guala-Valverde, P. Mazzoni, and K. Blas, ibid. 65, 147-148 (1997)]. We provide a suitable variation on a recent work "The Unipolar Dynamotor: A Genuine Relational Engine'' [J. Guala-Valverde and P. Mazzoni, Apeiron 8, 41-52 (2001)], where "relational'' implies "absolutely relativistic.'' Our view agrees with both Weber's recognition in the 19th century of the importance of relative motion in electromagnetic phenomena [A. K. T. Assis, Electrodynamics (Kluwer, Dordrecht, 1994)] and Einstein's 1905 statement concerning electromagnetism [Ann. Phys. 17, 891-921 (1905)].

With the aid of the random electrodynamics (a classical statistical theory based upon a Lorentz invariant spectral density) we revisite at a heuristic level some simple but interesting physical systems.

We describe two quasi trivial, old fashioned, but cleverly conceived, undisputable, experiments which disprove Kennard-type absolutistic interpretations of unipolar machines. Our findings are in agreement with Weber's statements concerning the role of relative motion in electrodynamics, as advanced by himself towards the middle of the 19th century. And also we agree with Mach's views concerning motion at the most general level. This work settles our earlier contributions devoted to unipolar induction. For nearly a century after its discovery by Faraday in 1832 the unipolar generator was a conundrum for the theory of electromagnetism D. F. Bartlett et al. Phys. Rev D 16 (12), 3459 (1977). We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. - Isaac Newton

We probe a theorem recently advanced in this journal.

In (Assis 1998, pp. 241-249) and (Assis 1999, pp. 199-205) it was said that if we double the average matter density of the distant universe (galaxies), while keeping constant the matter density of the earth and all sizes and distances, the acceleration of free fall halves (that is, goes to 4.9m/s^{2} instead of the usual 9.8m/s^{2}). Guala-Valverde concluded that in this case the acceleration of free fall should go to (9.8m/s^{2}) / 2, see (Guala-Valverde 1999a and 1999b, p. 25). But this was only due to a misunderstanding. Guala-Valverde was thinking on doubling the average inertial mass density of distant galaxies, while Assis was talking of doubling the average gravitational mass density of distant matter (see (Assis 1998, pp. 207, 211 and 246) or (Assis 1999, pp. 170, 174 or 204). This solves all misunderstandings. That is, Guala-Valverde and Assis agree that doubling the gravitational mass density of distant matter (while keeping unalterable Hubble's constant, the gravitational mass of the earth and its radius) will make the acceleration of free fall go to 4.9 m/s^{2}. So our results are not clashing, it was all due to a misunderstanding.

The rate at which a satellite clock CS runs and the rate at which a terrestrial CE runs are here shown to be simply linked through basic energetics and Planck?s law.

Using Dimensional Analysis we have improved a paper of Assis published in 1989, deriving, at first once, the right connection between gravitational mass and inertial mass for any body in the universe.

When a charge moves, an electromagnetic field surrounding it appears. This field interacts with circuits, resulting in electromotive and ponderomotive phenomena. When a charge is at rest, the field reduces to the Coulomb field; the magnetic part of the Lorentz force **F **= *q*u X **B **is absent and neither pondero- nor electro-motive forces appear, *no matter how magnets and circuits move.* It is shown that neither absolute space nor STR are necessary to explain unipolar induction effect.

It is suggested that the gravitational redshift occurs not on the journey of the light from source to distination, but during the emission of the photon at the energy level affected by the gravitational field.

The motion of a particle in a gravitational field is analyzed taking into account the inertia to be associated with the potential energy. Louis de Broglie noted in 1924 that inertial mass must be associated with potential energy. The mass defect is calculated for all particles at rest in a gravitational field. This accounts for the gravitational red shift.