On the harmonic map equation
A generalized harmonic map equation is presented based on the proposed action functional in the Weyl space (PLA, 135, 315, 1989).
gr-qc↗
arXiv subjects
S. C. Tiwari
Publications and source records attributed to S. C. Tiwari.
Viscous Spacetime Fluid and Higher Curvature Gravity
The Einstein field equation as an equation of state of a thermodynamical system of spacetime is reconsidered in the present Letter. We argue that a consistent interpretation leads us to identify scalar curvature and cosmological constant terms representing the bulk viscosity of the spacetime fluid. Since Einstein equation itself corresponds to a near-equilibrium state in this interpretation invoking $f(R)$ gravity for nonequilibrium thermodynamics is not required. A logically consistent generalization to include the effect of so called 'tidal forces' due to the Riemann curvature is presented. A new equation of state for higher curvature gravity is derived and its physical interpretation is discussed.
gr-qc↗
Comment on "Cyclotron resonance study of the electron and hole velocity in graphene monolayers"
In this comment it is pointed out that the electron velocity of the same order as observed in graphene had been measured in GaAs submicron devices long ago. Particle- antiparticle asymmetry related with electron and hole effective masses in graphene seems puzzling as hole in a condensed matter system cannot be treated as anti-electron. It is argued that there should be a universal electrodynamics for QHE and superconductivity. In this context attention is drawn to the new approach based on massless electron and the interpretation that magnetic field represents angular momentum of the photon fluid. Measurement of electron velocity in graphene and GaAs in parallel is suggested for testing the massless electrodynamics.
physics.gen-ph↗
Nature of the Angular Momentum of Light: Rotational Energy and Geometric Phase
The nature of intrinsic/extrinsic character of angular momentum is defined in terms of the kind of the associated rotational energy of the light. The salient features of the spin energy of light and photon are highlighted. Spin angular momentum is intrinsic while orbital angular momentum possesses quasi-intrinsicness only if the vortex-like singularities are present. The claimed spin to orbital angular momentum conversion is interpreted in terms of spin redirection geometric phase. It is pointed out that this interpretation validates our angular momentum holonomy conjecture.
quant-ph↗
Photon Spin, Zero-point Energy and Black-body radiation
A critical review of the obscure nature of the contribution of spin energy to the energy of the electromagnetic field is presented. It is proposed that the total energy of photon hνcomprises of kinetic and spin parts each equal to hν/2. Classical magnetic field is reinterpreted as angular momentum flux of photon fluid. The black-body radiation law is revisited in the light of new significance of the zero-point energy proposed here.
quant-ph↗
Pancharatnam Phase and Photon Polarization Optics
Parallel transport of a vector around a closed curve on the surface of a sphere leads to a direction holonomy which can be related with a geometric phase that is equal to the solid angle subtended by the closed curve. Since Pancharatnam phase is half of the solid angle subtended by the polarization cycle on the Poincare sphere, quantum parallel transport law takes recourse o spin-half wave function to obtain this result. A critique is offered on this factor of half anomaly in the geometric phase, and a natural resolution using Riemann sphere polarization representation is suggested. It is argued that spin angular momentum of photon is fundamental in polarization optics, and new insights are gained based on the hypothesis that two helicity states correspond to two distinct species of photon. This approach leads to the concept of a physical Poincare sphere: nonlinearity and jumps in the Pancharatnam phase find a simple physical explanation while novel features pertaining to the discrete and pulsating sphere are predicted. Paired photon spin zero structure of unpolarized light is also discussed. An outline of possible experimental tests is presented.
physics.gen-ph↗
Comment on "Roentgen quantum phase shift: a semiclassical local electrodynamical effect?"
In this short note we amplify our comments on the paper PRL 95,010405 (2005).
physics.gen-ph↗
Massless Electron and Fractional Spin as Electronic Charge
The standard model (SM) of particle physics has been supported by several experimental findings, the most remarkable of them being the discovery of the weak gauge bosons, W and Z. It is expected that the Higgs boson could show up by 2007 at LHC, CERN. In spite of this, the unsatisfactory features of the SM at conceptual level, and exclusion of gravity from the unification scheme have led to explore 'the physics beyond the SM'. A critique and comprehensive review of the contemporary fundamental physics was presented in a monograph completed in the centenary year,1997 of the discovery of the electron. A radically new approach to address foundational problems was outlined: masslessness of bare electron, interpretation of the squared electronic charge in terms of the fractional spin, $e^2/c$; new physicalsignificance of the electromagnetic potentials, 2+1 dimensional internal structure of electron and neutrino, and composite photon are some of the ideas proposed. Though the monograph was reviewed by E. J. Post(Physics Essays, June1999), it has remained largely inaccessible. I believe some of these unconventional ideas have a potential to throw light on the fundamental questions in physics, and therefore deserve a wider dissemination. The reader may find illuminating to supplement Section 3 on the weak gauge bosons with a candid, graceful and personal recollection by Pierre Darriulat(CERN Courier, April 2004, p.13).
physics.gen-ph↗
On the anomalous extreme ultraviolet emission lines in helium-hydrogen plasma
The idea of photonic de Broglie waves is discussed in the context of recent obsrved lines in the helium-hydrogen plasma.
physics.plasm-ph↗
Unimodular relativity and cosmological constant : Comments
We show that the conclusion that matter stress-energy tensor satisfies the usual covariant continuity law, and the cosmological constant is still a constant of integration arrived at by Finkelstein et al (42, 340, 2001) is not valid.
gr-qc↗
Comments on "Geometric Phase Associated with Transformations of Optical Beams Bearing Orbital Angular Momentum"
In the present note I am presenting my point of view about the idea proposed in the above said paper.
physics.optics↗
Electron in the Einstein-Weyl space
The classical unified theory of Weyl is revisited. The possibility of stable extended electron model in the Einstein-Weyl space is suggested.
gr-qc↗
Time varying velocity of light
Recently there has been a lot of intersest in the superluminal phenomena, and time varying velocity of light cosmological models. More than two decades ago at Einstein centenary symposium, Nagpur I had put forward space-time interaction hypothesis. One of its predictions was that velocity of light decreased with the age of Universe. In view of the profoundness of the hypothesis the original paper is reproduced here. We also mention that in a paper "Quasars, Tachyons and the early universe" proc. Einstein found. Intnl. 2(3), 1985 pp 69-75, it was suggested that, "The boundary region of the universe being the source of radiation, the slowing down of the speed of radiation from $4.4 \times 10^{10}$ cm/sec at $t_A = 10^{10}$ yrs. to the present value of $3 \times 10^{10}$ cm/sec should show up as a large red shifts. The successive boundary region radiations at various epoch will give rise to a wide range of red shifts. Therefore, defining quasars as the objects having two properties: large red shifts and powerful emission of radiations, we would like to identify these objects as the boundary regions of the universe".
gr-qc↗
Time and Cosmic Clock
The nature of time vis-a-vis relativity is critically examined. Based on the author's space-time interaction hypothesis of late 1970's, cosmological model with time-varying velocity of light is discussed.
gr-qc↗
Reality of Time
The meaning of instantaneous action at a distance is elucidated. It is shown that the absence of a medium to transmit action (usually referred to as AAD in the literature) and instantaneous action are not identical. Since the term "instantaneous" is incompatible with relativity and field theory, a critique is presented on the concept of time in relativity. It is argued that relativity does not deal with the nature of time. Physical reality of the absolute time is envisaged, and instantaneous action is proposed to be a natural consequence of it. Possibly gravity is such kind of a force, however the electromagnetic force, though envisaged as direct particle interaction (i.e. without intermediary fields) can not be instantaneous.
physics.gen-ph↗
Geometry of Quantum Theory: Weyl-Kahler Space
A new space namely the Weyl-Kahler is proposed to the quantum state space. Some of the physical consequences are discussed.
quant-ph↗
Relativity and EPR Entanglement: Comments
Recent experiment by Zhinden et al (Phys. Rev {\bf A} 63 02111, 2001) purports to test compatibility between relativity and quantum mechanics in the classic EPR setting. We argue that relativity has no role in the EPR argument based solely on non-relativistic quantum formalism. It is suggested that this interesting experiment may have significance to address fundamental questions on quantum probability.
quant-ph↗