Electromagnetism

In this paper, the authors have detected a new effect in the area of geomagnetism, related to the behavior of a magnetic dipole freely floating on water surface. An experiment is described in the present paper in which a magnetic dipole fixed upon a float placed on non- magnetized water surface undergoes displacement along with reorientation caused by fine structure of the earth's magnetic field. This fact can probably be explained by secular decrease of the earth's major dipole moment. Further, (...) a detailed study of the phenomenon may create interesting premises for its practical use, particularly for the analysis of fine structure of geomagnetic field and its time-dependent anomalies. A strange behavior of some sea fish species prior to strong earthquakes may be explained if the fish are assumed as 'live magnetic dipoles'. (shrink)

The properties of angular momentum and its connection to magnetic momentum are explored, based on a reconsideration of the Stern-Gerlach experiment and gauge invariance. A possible way to solve the so called spin crisis is proposed. The separation of angular momentum of a quan- tum system of particles into orbital angular momentum plus intrinsic angular momentum is reconsidered, within the limits of the Schrodinger theory. A proof is given that, for systems of more than two particles, un- less all of (...) them have the same mass, the possibility of having eigenvalues of the form (n + 1/2)h is not excluded. (shrink)

We have evaluated analytically the vacuum polarization in a Coulomb field using the relativistic Dirac-Coulomb wave functions by a new method. The result is made finite by an appropriate choice of contour integrations and gives the standard result in the lowest order of iteration. We used the formalism of self-field quantum electrodynamics in the evaluation of the vacuum polarization which needs neither field quantization nor renormalization. There are no infrared or ultraviolet divergences.

We considered peculiarities of the evolution of a region with sharp boundaries that is filled with a partially ionized plasma and is a part of the volume of a condensed target. The creation of such a region in the near-surface layer of the target can be related to the action of an external impulse symmetric ionizator or to the action of an intense small-extension shock wave on the target surface. We defined the conditions such that their fulfilment during the establishment (...) of the equilibrium between the Coulomb attraction of electrons and ions with atom ionization multiplicity Z* 1 and the kinetic pressure of electrons causes both the compression of this region and its ionization to the state with Z* 2 > Z* 1. The last leads to a further additional compression and ionization. Under these conditions, the spontaneous avalanche-like ionization of atoms of the target to the state of ‘‘bare’’ nuclei occurs synchronously with the avalanche-like metallization and the self-compression of the target. We showed that the avalanche-like ionization and the self-compression of the target happen in the case where the gas of degenerate electrons has drift momentum. If the region with initial ionization has the form of thin spherical layer, the process of avalanche-like ionization and self-compression of the target in this region is accompanied by the accelerated movement of the plasma layer to the target center. One of the reasons for the accelerated movement is the surface tension in a bounded domain of the nonequilibrium plasma layer neutralized by ions of the target. With increase in the velocity of movement of this layer to the target center, the additional self-compression of the system of electrons and nuclei to the state of degenerate electron gas occurs. At the leading edge of the running layer with extremely high electron density which is neutralized by nuclei of the target, the formation of a collapse of the electron--nucleus system proceeds, and the binding energy maximum for the electron--nucleus system shifts from A≈60 to A ≫ 60. This result makes possible the fast synthesis of superheavy nuclei. The decay of the collapse state, a partial restoration of the target structure, its rapid cooling, and the condensation of a part of the products of nuclear reactions happen in the target volume at the trailing edge of the moving plasma layer. Upon such a scanning propagation of the wave with high electron density, all the target substance is involved, step-by-step, to the process of nuclear transformations. At the target center, the moving plasma layer is squeezed with the formation of the state of quasistationary collapse under inertial confinement. Then the collapse state decays irreversibly. (shrink)

The theory of scale-covariant gravity is extended to include charged matter and electromagnetism at the classical level. The possibility of charge creation exists and the creation rate of charge differs from the creation rate of matter. A variational principle for scale-covariant gravity and electromagnetism coupled to a charged perfect fluid is given.

The present document starts from the relative existence of the electromagnetic field, reaching through mental experiments to its connection with the gravitational field, without the necessity to resort to other space - time dimensions or supplementary "exotic" particles. The final conclusion is that the field "electro-gravitational" and electromagnetic field with accelerated source are two different manifestations of the same single field dynamic. Whilst demonstrating why there are light sources with "flee" towards the red or blue of the light spectrum.

In discussions of the Aharonov-Bohm effect, Healey and Lyre have attributed reality to loops $\sigma_0$ (or hoops $[\sigma_0]$), since the electromagnetic potential $A$ is currently unmeasurable and can therefore be transformed. I argue that $[A]=[A+d\lambda]_{\lambda}$ and the hoop $[\sigma_0]$ are related by a meaningful duality, so that however one feels about $[A]$ (or any potential $A\in[A]$), it is no worse than $[\sigma_0]$ (or any loop $\sigma_0\in[\sigma_0]$): no ontological firmness is gained by retreating to the loops, which are just as flimsy (...) as the potentials. And one wonders how the unmeasurability of one entity can invest another with physical reality; would an eventual observation of $A$ dissolve $\sigma_0$, consigning it to a realm of incorporeal mathematical abstractions? The reification of loops rests on the potential's ''gauge dependence''; which in turn rests on its unmeasurability; which is too shaky and arbitrary a notion to carry so much weight. (shrink)

I present the current experimental and theoretical work on interference in complementary spaces. These ideas are applicable to both light and matter waves. I give a detailed treatment for classical light beams in frequency and time domains. I also present a description which gives the totality of interferences.

Measurement of gravitomagnetic field is of fundamental importance as a test of general relativity. Here we present a new theoretical project for performing such a measurement based on detection of the electric field arising from the interplay between the gravitomagnetic and magnetic fields in the stationary axial-symmetric gravitational field of a slowly rotating massive body. Finally it is shown that precise magnetometers based on superconducting quantum interferometers could not be designed for measurement of the gravitomagnetically induced magnetic field in the (...) cavity of a charged capacitor since they measure the circulation of a vector potential of electromagnetic field, i.e., an invariant quantity including the sum of electric and magnetic fields, and the general-relativistic magnetic part will be totally cancelled by the electric one which is in good agreement with the experimental results. (shrink)

In preparation for the treatment of the gravitational field at spatial infinity, this paper deals with the electromagnetic field at spatial infinity. The field equations on this three-dimensional(1+2) manifold can be obtained from an action principle, which in turn lends itself to a Hamiltonian formulation. Quantization is formally straightforward, but some thought is given to the physical interpretation of the results.

We consider the Dirac equation in 3+1 dimensions with spherical symmetry and coupling to 1/r singular vector potential. An approximate analytic solution for all angular momenta is obtained. The approximation is made for the 1/r orbital term in the Dirac equation itself not for the traditional and more singular 1/r 2 term in the resulting second order differential equation. Consequently, the validity of the solution is for a wider energy spectrum. As examples, we consider the Hulthén and Eckart potentials.

In this paper, I argue that the recent discussion on the time - reversal invariance of classical electrodynamics (see (Albert 2000: ch.1), (Arntzenius 2004), (Earman 2002), (Malament 2004),(Horwich 1987: ch.3)) can be best understood assuming that the disagreement among the various authors is actually a disagreement about the metaphysics of classical electrodynamics. If so, the controversy will not be resolved until we have established which alternative is the most natural. It turns out that we have a paradox, namely that the (...) following three claims are incompatible: the electromagnetic fields are real, classical electrodynamics is time-reversal invariant, and the content of the state of affairs of the world does not depend on whether it belongs to a forward or a backward sequence of states of the world. (shrink)

The sign of the Soret coefficient S T of a large set of ionic magnetic colloids ) and surfacted magnetic colloids ) is determined using forced Rayleigh scattering and the single-beam Z -scan techniques. Different samples were investigated: acid and alkaline colloids with different values of pH; colloids with different concentrations of magnetic grains; colloids with grains of different typical diameters; colloids with magnetic grains with different coating natures; colloids with different non-polar and polar liquid carriers. Our results indicate that (...) the sign of S T depends on the sign of the surface charge of grains in IFFs. In the case of water-based SFFs, the thermodiffusive behaviour is opposite to that of IFFs; that is, grains coated with a cationic surfactant behave like negatively charged IFF grains and grains coated with an anionic surfactant behave like positively charged IFF grains. SFFs with grains coated with non-ionic surfactants dispersed in non-polar fluid carriers behave like SFFs with grains coated with a cationic surfactant. The nature of the liquid carrier itself is not the only determinant factor, except apparently in the case of non-polar fluids, where only S T > 0 is found. These results cannot be explained with the available theories and it is highly probable that different mechanisms are present in the thermodiffusive behaviour of these complex fluids. (shrink)

To infer ontological features in the domain of a physical theory from its mathematical structures often requires one to consider an interpretation of the structures which goes beyond that necessary to provide an empirically adequate theory. I undertake this task for a set of mathematical structures of classical electromagnetism known as potentials. ;Since their first use in the nineteenth century through to their role within contemporary quantum theory, their interpretation has posed a number of problems and has sometimes been the (...) subject of controversy. The dominant interpretation outside the quantum context since the time of Heaviside and Hertz has been that they function as mere mathematical auxiliaries within the theory with no physical significance other than the electric and magnetic fields derived from them. ;By investigating the role of potentials in the field theory tradition of classical electromagnetism from its origins through to the present, I argue that this position is neither the necessary nor the proper one for interpreting potentials. My investigation begins with Faraday and includes the work of Maxwell, the "Maxwellians," and Weyl. I am able to counter the usual perspective by locating the precise reason for its establishment and showing why these reasons need not hold when the manner in which potentials represent empirical phenomena is properly understood. I further argue that there are good reasons to see the potential structures as vital to understanding the depth structure of electromagnetic theory. On this basis I argue to a number of ontological conclusions about the nature of the classical electromagnetic field. ;I also examine the role of the potentials as representing unquantized fields in quantum mechanics by a close examination of the Aharonov-Bohm effect. I argue that potentials now reveal fields as possessing a global, non-local property, with a sense of non-locality which I distinguish from the usual understanding of non-locality associated with this effect as well as from that associated with measurements on systems with correlated quantum states. (shrink)

We report a magnetization, magnetostriction, electrical resistivity, specific heat and neutron scattering study of a UNi 2/3 Rh 1/3 Al single crystal, a solid solution of an antiferromagnet UNiAl and a ferromagnet URhAl. The huge uniaxial magnetic anisotropy confining the principal magnetic response to the c axis in the parent compounds persists also for the solid solution. The magnetization curve at 1.6 K has a pronounced S shape with an inflection at 12 T. The temperature dependence of magnetic susceptibility exhibits (...) a maximum around 10 K and is magnetic history dependent at lower temperatures where the resistivity increases linearly with decreasing temperature. The low-temperature „ anomaly is removed in a magnetic field applied along c , which yields a large negative magnetoresistance amounting to m 46 z in 14 T . The C/T values exhibit a minimum around 12 K and below 8 K they become nearly constant , which is strongly affected by magnetic fields. Neutron scattering data confirm a non-magnetic ground state of UNi 2/3 Rh 1/3 Al. The bulk properties at low temperatures are tentatively attributed to the freezing of U magnetic moments with antiferromagnetic correlations. The additional intensities detected on top of nuclear reflections in neutron diffraction in a magnetic field applied along c are found to be proportional to the field-induced magnetization, which reflects field-induced ferromagnetic coupling of U magnetic moments. This scenario is corroborated also by finding low-temperature magnetostriction data that also scale with the square of magnetization. (shrink)