4,561 research outputs found
Convection displacement current and alternative form of Maxwell-Lorentz equations
Some mathematical inconsistencies in the conventional form of Maxwell's
equations extended by Lorentz for a single charge system are discussed. To
surmount these in framework of Maxwellian theory, a novel convection
displacement current is considered as additional and complementary to the
famous Maxwell displacement current. It is shown that this form of the
Maxwell-Lorentz equations is similar to that proposed by Hertz for
electrodynamics of bodies in motion. Original Maxwell's equations can be
considered as a valid approximation for a continuous and closed (or going to
infinity) conduction current. It is also proved that our novel form of the
Maxwell-Lorentz equations is relativistically invariant. In particular, a
relativistically invariant gauge for quasistatic fields has been found to
replace the non-invariant Coulomb gauge. The new gauge condition contains the
famous relationship between electric and magnetic potentials for one uniformly
moving charge that is usually attributed to the Lorentz transformations. Thus,
for the first time, using the convection displacement current, a physical
interpretation is given to the relationship between the components of the
four-vector of quasistatic potentials. A rigorous application of the new gauge
transformation with the Lorentz gauge transforms the basic field equations into
an independent pair of differential equations responsible for longitudinal and
transverse fields, respectively. The longitudinal components can be interpreted
exclusively from the standpoint of the instantaneous "action at a distance"
concept and leads to necessary conceptual revision of the conventional
Faraday-Maxwell field. The concept of electrodynamic dualism is proposed for
self-consistent classical electrodynamics. It implies simultaneous coexistenceComment: ReVTeX file, 29pp., no figure
Ether and Electrons in Relativity Theory
This chapter discusses the roles of ether and electrons in relativity theory. One of the most radical moves made by Albert Einstein was to dismiss the ether from electrodynamics. His fellow physicists felt challenged by Einstein’s view, and they came up with a variety of responses, ranging from enthusiastic approval, to dismissive rejection. Among the naysayers were the electron theorists, who were unanimous in their affirmation of the ether, even if they agreed with other aspects of Einstein’s theory of relativity. The eventual success of the latter theory (circa 1911) owed much to Hermann Minkowski’s idea of four-dimensional spacetime, which was portrayed as a conceptual substitute of sorts for the ether
Accelerated Expansion as Predicted by an Ether Theory of Gravitation
Cosmology is investigated within a new, scalar theory of gravitation, which
is a preferred-frame bimetric theory with flat background metric. Before coming
to cosmology, the motivation for an " ether theory " is exposed at length; the
investigated concept of ether is presented: it is a compressible fluid, and
gravity is seen as Archimedes' thrust due to the pressure gradient in that
fluid. The construction of the theory is explained and the current status of
the experimental confrontation is analysed, both in some detail. An analytical
cosmological solution is obtained for a general form of the energy-momentum
tensor. According to that theory, expansion is necessarily accelerated, both by
vacuum and even by matter. In one case, the theory predicts expansion, the
density increasing without limit as time goes back to infinity. High density is
thus obtained in the past, without a big-bang singularity. In the other case,
the Universe follows a sequence of (non-identical) contraction-expansion
cycles, each with finite maximum energy density; the current expansion phase
will end by infinite dilution in some six billions of years. The density ratio
of the present cycle (ratio of the maximum to current densities) is not
determined by the current density and the current Hubble constant H0, unless a
special assumption is made. Since cosmological redshifts approaching z = 4 are
observed, the density ratio should be at least 100. From this and the estimate
of H0, the time spent since the maximum density is constrained to be larger
than several hundreds of billions of years. Yet if a high density ratio,
compatible with the standard explanation for the light elements and the 2.7 K
radiation, is assumed, then the age of the Universe is much larger still.Comment: 32 pages, Post-Script. v4 : Section 2 (general presentation of the
theory and its motivation) still reinforced, Subsection 5.3 added (Comments
on accelerated expansion and infinite dilution). To appear in "Physics
Essays", Vol. 14, No. 1, 200
From aether theory to Special Relativity
At the end of the 19th century light was regarded as an electromagnetic wave
propagating in a material medium called ether. The speed c appearing in
Maxwell's wave equations was the speed of light with respect to the ether.
Therefore, according to the Galilean addition of velocities, the speed of light
in the laboratory would differ from c. The measure of such difference would
reveal the motion of the laboratory (the Earth) relative to the ether (a sort
of absolute motion). However the Earth's absolute motion was never evidenced.
Galileo addition of velocities is based on the assumption that lengths and
time intervals are invariant (independent of the state of motion). This way of
thinking the spacetime emanates from our daily experience and lies at the heart
of Newton's Classical Mechanics. Nevertheless, in 1905 Einstein defied Galileo
addition of velocities by postulating that light travels at the same speed c in
any inertial frame. In doing so, Einstein extended the principle of relativity
to the electromagnetic phenomena described by Maxwell's laws. In Einstein's
Special Relativity the ether does not exist and the absolute motion is devoid
of meaning. The invariance of the speed of light forced the replacement of
Galileo transformations with Lorentz transformations. Thus, relativistic length
contractions and time dilations entered our understanding of the spacetime.
Newtonian mechanics had to be reformulated, which led to the discovery of the
mass-energy equivalence.Comment: 24 pages, 9 figures. To appear in Handbook of Spacetime, edited by A.
Ashtekar and V. Petkov, Springer-Verlag Gmb
Are Electrons Oscillating Photons, Oscillating “Vacuum," or Something Else? The 2015 Panel Discussion: An Unprecedented Engineering Opportunity: A Dynamical Linear Theory of Energy as Light and Matter
Platform: What physical attributes separate EM waves, of the enormous band of radio to visible to x-ray, from the high energy narrow band of gamma-ray? From radio to visible to x-ray, telescopes are designed based upon the optical imaging theory; which is an extension of the Huygens-Fresnel diffraction integral. Do we understand the physical properties of gamma rays that defy us to manipulate them similarly? One demonstrated unique property of gamma rays is that they can be converted to elementary particles (electron and positron pair); or a particle-antiparticle pair can be converted into gamma rays. Thus, EM waves and elementary particles, being inter-convertible; we cannot expect to understand the deeper nature of light without succeeding to find structural inter-relationship between photons and particles. This topic is directly relevant to develop a deeper understanding of the nature of light; which will, in turn, help our engineers to invent better optical instruments
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