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S. C. Tiwari

Publications and source records attributed to S. C. Tiwari.

At least 19 recordsLinked to original sources
arXiv2024

Comments on "A clarification on prevailing misconceptions in unimodular gravity"

In this comment on arXiv:2308.07360 it is pointed out that though the authors raise an important question on the prevailing presentations of the unimodular gravity their own presentation is incomplete as well as confusing equating assumptions to misconceptions. We focus on the notion of diffeomorphism invariance, general covariance and the conservation/nonconservation of the energy-momentum tensor in this short note to delineate the fundamental issues in unimodular gravity. The present discussion is intended to offer a wider and deeper perspective on the objective set by the authors in their paper.

gr-qc↗
arXiv2023

New Approach to Unimodular Relativity

A thorough study and analysis on the conceptual foundations of unimodular gravity shows that this theory is essentially general relativity disguised as unimodular relativity in the literature. The main reason for this dilemma is accepting the Einsteinian paradigm: general relativistic framework, covariant divergence law for matter energy-momentum tensor, and cosmological constant as an integration constant, but introducing the artefact of unimodular description absent in Einstein's work. A new approach is proposed in this paper in which pure unimodular relativity is defined in terms of equi-projective geodesics with the fundamental metric tensor having determinant unity and the geometric tensors constructed from them. Modification of covariant divergence law for the matter energy-momentum tensor is shown to have two new consequences. In the conventional unimodular gravity an effective cosmological term comprising of two variable scalar fields, namely, the unimodular geometric ambiguity and unimodular matter energy ambiguity, is proposed. A radical departure on the cosmological constant problem is possible assuming differing evolution of the two scalars: the Einstein equations emerge when the two ambiguities cancel each other. Secondly, in the case of pure unimodular relativity the gravitational field equations are proposed consistent with the unimodular space-time structure.

physics.gen-ph↗
arXiv2020

Weyl geometry, topology of space-time and reality of electromagnetic potentials, and new perspective on particle physics

Consistency of Weyl natural gauge, Lorentz gauge and nonlinear gauge is studied in Weyl geometry. Field equations in generalized Weyl-Dirac theory show that spinless electron and photon are topological defects. Statistical metric and fluctuating metric in 3D space with time as a measure of spatial relations are discussed to propose a statistical interpretation of Maxwell field equations. It is argued that physical geometry is an approximation to mathematical geometry, and 4D relativistic spacetime is essentially 3D space with changing spatial relations. The present work is suggested to have radical new outlook on elementary particle physics.

physics.gen-ph↗
arXiv2020

On the dark energy

The dark energy problem may have a simple solution in the model of cosmology based on the space-time interaction hypothesis. The hypothesis throws light on the nature of time (see Time-Transcendence-Truth, Monograph published in 2006).

physics.gen-ph↗
arXiv2019

Physics and mathematical reality: comments on Aharonov et al, arXiv:1902.08798

Do we have two kinds of reality: physical and mathematical? What is the role of mathematics in physics? These fundamental questions have intrigued original and brilliant minds since ancient times. A recent article (Aharonov, Cohen and Oaknin, arXiv:1902.08798) offers a viewpoint on the use of abstract mathematics in quantum theory. They argue that, in some cases, it may result into a paradox focusing on an example in quantum mechanics regarding Aharonov-Bergmann-Lebowitz (ABL) rule. In this comment we discuss three issues: theory reduction and approximation, origin of a paradox, and the reality of time. It is pointed out that paradoxes appear even in mathematics; we explain them as the results of the acceptance of pure logical artifacts. In physics too, the impact of the so called quantum and relativity revolutions, have led to the emergence of counter-intuitive and mysterious notion of the physical reality. The most fundamental change has been on rejecting the reality of time. A radically new perspective that physics is the language of mathematics is suggested. The mathematical reality of the natural numbers manifests in the form of physical time.

physics.gen-ph↗
arXiv2019

Coulomb- quantum oscillator correspondence in two dimension, pure gauge field and half-quantized vortex

Isotropic oscillator and Coulomb problems are known to have interesting correspondence. We focus on 2D quantum problems and present complete treatment on the correspondence including the Schroedinger equation, eigenfunctions and eigenvalues, and the integrals of motion. We find only partial equivalence. The wavefunction correspondence is examined introducing local gauge transformation and the emergence of half-quantized vortex with the associated spin-half is established. Vortex structure of the electron proposed by us and the origin of charge are discussed in the present context. Outlook on the implications for QCD and hadron spectrum is outlined.

physics.gen-ph↗
arXiv2017

Physical reality of electromagnetic potentials and the classical limit of the Aharonov-Bohm effect

Recent literature on the Aharonov-Bohm effect has raised fundamental questions on the classical correspondence of this effect and the physical reality of the electromagnetic potentials in quantum mechanics. Reappraisal on Feynman's approach to the classical limit of AB effect is presented. The critique throws light on the significance of quantum interference and quantum phase shifts in any such classical correspondence. Detailed analysis shows that Feynman arguments are untenable on physical grounds and the claim made in the original AB paper that this effect had no classical analog seems valid. The importance of nonintegrable phase factor distinct from the AB phase factor, here termed as Fock-London-Weyl phase factor for the historical reasons, is underlined in connection with the classical aspects/limits. A topological approach incorporating the physical significance of the interaction field momentum is proposed. A new idea emerges from this approach that attributes the origin of the AB effect to the exchange of modular angular momentum.

physics.gen-ph↗
arXiv2017

Gordon decomposition of Dirac current: a new interpretation

Historically Gordon decomposition of Dirac current played an important role in the interpretation of Dirac equation. We revisit it to understand the correspondence between Maxwell-Dirac and Maxwell-Lorentz theories. Arguments are presented to show that classical charge current corresponds to Gordon current. Consistency with Maxwell-Dirac theory leads to a new result: antisymmetric spin tensor in spin magnetization current of Dirac electron must be hidden as internal part of classical Maxwell tensor. It becomes natural to extend our previous interpretation in which electromagnetic field tensor represents angular momentum of photon or spacetime fluid (aether!) in the presence of sources such that the duality between field and source disappears. Both Gordon current and spin current are proposed to have 'spinning origin'. Formal expression of Gordon current makes it possible to apply the idea of optical vortex in this case, and quantized vortex and quantized orbital angular momentum could be related with the conjecture of mechanical interpretation of electric charge. Separate mass and charge centers for spinning point charge are well known in the literature; we discuss them in the context of two-vortex model of electron and Gordon decomposition.

physics.gen-ph↗
arXiv2016

Topological approach to proton spin problem: decomposition controversy and beyond

Lorentz covariant and gauge invariant definitions of quark and gluon spin and orbital angular momenta continue to pose a great theoretical challenge. A major controversy on the fundamental concepts followed Chen et al proposal: the basic idea is to split the gauge potential into pure gauge and physical components motivated by the gauge symmetry. We term it gauge symmetry paradigm (GSP) to distinguish it from the well-known inertial frame dependent transverse-longitudinal decomposition (TLP). A thorough study adhering to the traditional meaning of Lorentz covariance and gauge invariance is reported; it leads to a new result: logically consistent development of GSP does not exist and Chen et al proposal turns out to be either trivial or metamorphosed into TLP. Going beyond the controversy and the spin sum rules the necessity for a nonperurbative QCD approach to address the proton spin problem is underlined. We suggest topological approach: generalized de Rham theorems for QCD, and spin as a topological invariant for baryons are discussed. Nonabelian Stokes theorem is applied to derive color flux for the closed loop in a variant of Burkardt's U-shaped path. Similarity between Chen et al decomposition and Kondo decomposition of the gauge potential is suggestive of a topological perspective on the Chen et al proposal with interesting physics

physics.gen-ph↗
arXiv2014

Lorentz covariance and gauge invariance in the proton spin problem

In this brief note insightful remarks are made on the controversy on the decomposition of the proton spin into the spin and orbital angular momenta of quarks and gluons. It is argued that the difference in the perception on the nature of the problem is the main reason for the persistent disputes. There is no decomposition that simultaneously satisfies the twin principles of manifest Lorentz covariance and gauge invariance, and partial considerations hide likely inconsistencies. It is suggested that field equations and matter (i. e. electron in QED and quarks in QCD) equations must be analyzed afresh rather than beginning with the expressions of total angular momentum; canonical or otherwise.

physics.gen-ph↗
arXiv2012

On local duality invariance in electromagnetism

Duality is one of the oldest known symmetries of Maxwell equations. In recent years the significance of duality symmetry has been recognized in superstrings and high energy physics and there has been a renewed interest on the question of local duality rotation invariance. In the present paper we re-visit global duality symmetry in the Maxwell action and delineate the ambiguous role of gauge invariance and time locality. We have recently demonstrated that local duality invariance in a Lorentz covariant form can be carried out in the Maxwell equations. In this paper it is shown that in the four-pseudo vector Lagrangian theory of Sudbery a local duality generalization can be naturally and unambiguously implemented and the Euler-Lagrange equations of motion are consistent with the generalized Maxwell field equations. It is pointed out that the extension of Noether theorem in full generality for a vector action is an important open problem in mathematical physics. Physical consequences of this theory for polarized light and topological insulators are also discussed.

physics.gen-ph↗
arXiv2012

Two-vortex structure of electron, nonlocality and Dirac equation

The dimensionless electromagnetic coupling constant $α=e^2 /\hbar c$ may have three interpretations: as the well known ratio between the electron charge radius $e^2/mc^2$ and the Compton wavelength of electron $λ_c= \hbar /mc$, as a ratio of two angular momenta since Planck constant has the dimension of angular momentum, and two flux quanta $e$ and $hc/e$. The anomalous part of the electron magnetic moment together with the unified picture of the three interpretations of $α$ is suggested to have deep physical significance. The electric charge is proposed to be a new quantum of flux such that a two-vortex structure of electron is envisaged. In analogy with quantum conditions we postulate sub-quantum conditions applicable in a region of the order of $λ_c$ replacing $\hbar$ by a universal constant $f=e^2 /2πc$ and apply it to Dirac equation in internal space that gives rise to the anomalous magnetic moment of electron. Dirac spinor and 2-spinor representation for vortex structure of electron in the single particle Dirac framework are discussed. The role of sub-quantum rules and the internal variables for developing the present ideas is also debated. A critical discussion on the past attempts to give fundamental importance to magnetism and flux quantum is given to delineate the new ideas in the present work.

physics.gen-ph↗
arXiv2011

Role of local duality invariance in axion electrodynamics of topological insulators

Advances in material technology and confluence of ideas from particle physics, quantum field theory and condensed matter physics have led to the discovery of new states of matter as well as new physical phenomena: one of them termed as topological insulator has attracted a great deal of attention recently. Speculations on the possibility of observing the most elusive objects like axions and monopoles in topological insulators have led to studies that emphasize the role of symmetry and universality. In this paper we argue that electric-magnetic duality could be of deep significance in this context. We develop a duality invariant theory of topological insulators and show that under appropriate conditions this theory reduces to the axion electrodynamics for static case, topological quantization is related with the multi-valuedness of the duality gauge potential, and modifies Faraday's law for dynamical axion that would change the dispersion relation of axionic polariton. A new effect dual to the dynamical axion field effect is predicted and its physical consequences are discussed.

physics.gen-ph↗
arXiv2011

Electric Charge, Fractional Spin and Flux

Ratio of electron charge radius and Compton wavelength of electron is known to be equal to the dimensionless electromagnetic coupling constant $e^2 /\hbar c$. It is pointed out that the coupling constant has two alternative interpretations: as a ratio of two angular momenta since Planck constant has the dimension of angular momentum, and two flux quanta $e$ and $hc/e$. We argue that it has deep physical significance such that the electronic charge becomes flus itself and at a fundamental level fractional spin of quantized vortex. A unified perspective of the three interpretations of the coupling constant is presented invoking the new interpretation of the magnetic moment of the electron comprising of three terms. A critical discussion on the past attempts to give fundamental importance to magnetism and flux quantum is given and the implication on the unification quest of our ideas is outlined.

physics.gen-ph↗
arXiv2008

Rotating light, OAM paradox and relativistic complex scalar field

Recent studies show that the angular momentum, both spin and orbital, of rotating light beams possesses counter-intuitive characteristics. We present a new approach to the question of orbital angular momentum of light based on the complex massless scalar field representation of light. The covariant equation for the scalar field is treated in rotating system using the general relativistic framework. First we show the equivalence of the U(1) gauge current for the scalar field with the Poynting vector continuity equation for paraxial light, and then apply the formalism to the calculation of the orbital angular momentum of rotating light beams. If the difference between the co-, contra-, and physical quantities is properly accounted for there does not result any paradox in the orbital angular momentum of rotating light. An artificial analogue of the paradoxical situation could be constructed but it is wrong within the present formalism. It is shown that the orbital angular momentum of rotating beam comprising of modes with opposite azimuthal indices corresponds to that of rigid rotation. A short review on the electromagnetism in noninertial systems is presented to motivate a fully covariant Maxwell field approach in rotating system to address the rotating light phenomenon.

physics.gen-ph↗
arXiv2007

Double prism evanescent mode experiment: superluminal photons?

A critique on the interpretation of the double prism experiment on the evanescent microwave modes (arXiv:0708.0681) is presented. It is argued that these experiments do not give any evidence of superluminal photons. A physical mechanism based on the inhomogeneous waves of classical electromagnetic fields is proposed.

quant-ph↗