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W. A. Rodrigues Jr

Publications and source records attributed to W. A. Rodrigues Jr.

32 records · Page 2Linked to original sources
arXiv2003

Lagrangian Formalism for Multiform Fields on Minkowski Spacetime

We present an introduction to the mathematical theory of the Lagrangian formalism for multiform fields on Minkowski spacetime based on the multiform and extensor calculus. Our formulation gives a unified mathematical description for the main relativistic field theories including the gravitational field (which however will be discussed in a separate paper). We worked out several examples (including tricks of the trade), from simple to very sophisticated ones (like, e.g., the Dirac-Hestenes field on the more general gravitational background) which show the power and beauty of the formalism.

math-ph↗
arXiv2002

Euclidean Clifford Algebra

Let $V$ be a $n$-dimensional real vector space. In this paper we introduce the concept of \emph{euclidean} Clifford algebra $\mathcal{C\ell}(V,G_{E})$ for a given euclidean structure on $V,$ i.e., a pair $(V,G_{E})$ where $G_{E}$ is a euclidean metric for $V$ (also called an euclidean scalar product). Our construction of $\mathcal{C\ell}(V,G_{E})$ has been designed to produce a powerful computational tool. We start introducing the concept of \emph{multivectors} over $V.$ These objects are elements of a linear space over the real field, denoted by $\bigwedge V.$ We introduce moreover, the concepts of exterior and euclidean scalar product of multivectors. This permits the introduction of two \emph{contraction operators} on $\bigwedge V,$ and the concept of euclidean \emph{interior} algebras. Equipped with these notions an euclidean Clifford product is easily introduced. We worked out with considerable details several important identities and useful formulas, to help the reader to develope a skill on the subject, preparing himself for the reading of the following papers in this series.

math-ph↗
arXiv2002

Multivector Functions of a Multivector Variable

In this paper we develop with considerable details a theory of multivector functions of a $p$-vector variable. The concepts of limit, continuity and differentiability are rigorously studied. Several important types of derivatives for these multivector functions are introduced, as e.g., the $A$% -directional derivative (where $A$ is a $p$-vector) and the generalized concepts of curl, divergence and gradient. The derivation rules for different types of products of multivector functions and for compositon of multivector functions are proved.

math.GM↗
arXiv2002

Multivector Functionals

In this paper we introduce the concept of \emph{multivector functionals.} We study some possible kinds of derivative operators that can act in interesting ways on these objects such as, e.g., the $A$-directional derivative and the generalized concepts of curl, divergence and gradient. The derivation rules are rigorously proved. Since the subject of this paper has not been developed in previous literature, we work out in details several examples of derivation of multivector functionals.

math.GM↗
arXiv2002

Multivector Functions of a Real Variable

This paper is an introduction to the theory of multivector functions of a real variable. The notions of limit, continuity and derivative for these objects are given. The theory of multivector functions of a real variable, even being similar to the usual theory of vector functions of a real variable, has some subtle issues which make its presentation worhtwhile.We refer in particular to the derivative rules involving exterior and Clifford products, and also to the rule for derivation of a composition of an ordinary scalar function with a multivector function of a real variable.

math.GM↗
arXiv2002

Metric Clifford Algebra

In this paper we introduce the concept of metric Clifford algebra $\mathcal{C\ell}(V,g)$ for a $n$-dimensional real vector space $V$ endowed with a metric extensor $g$ whose signature is $(p,q)$, with $p+q=n$. The metric Clifford product on $\mathcal{C\ell}(V,g)$ appears as a well-defined \emph{deformation}(induced by $g$) of an euclidean Clifford product on $\mathcal{C\ell}(V)$. Associated with the metric extensor $g,$ there is a gauge metric extensor $h$ which codifies all the geometric information just contained in $g.$ The precise form of such $h$ is here determined. Moreover, we present and give a proof of the so-called \emph{golden formula,} which is important in many applications that naturally appear in ours studies of multivector functions, and differential geometry and theoretical physics.

math-ph↗
arXiv2002

Spin and Electron Structure

The recent literature shows a renewed interest, with various independent approaches, in the classical models for spin. Considering the possible interest of those results, at least for the electron case, we purpose in this paper to explore their physical and mathematical meaning, by the natural and powerful language of Clifford algebras (which, incidentally, will allow us to unify those different approaches). In such models, the ordinary electron is in general associated to the mean motion of a point--like "constituent" Q, whose trajectory is a cylindrical helix. We find, in particular, that the object Q obeys a new, non-linear Dirac--like equation, such that --when averaging over an internal cycle (which corresponds to a linearization)-- it transforms into the ordinary Dirac equation (valid, of course, for the electron as a whole).

quant-ph↗
arXiv2001

Causal explanation for observed superluminal behavior of microwave propagation in free space

In this paper we present a theoretical analysis of an experiment by Mugnai and collaborators where superluminal behavior was observed in the propagation of microwaves. We suggest that what was observed can be well approximated by the motion of a superluminal X wave. Furthermore the experimental results are also explained by the so called scissor effect which occurs with the convergence of pairs of signals coming from opposite points of an annular region of the mirror and forming an interference peak on the intersection axis traveling at superluminal speed. We clarify some misunderstandings concerning this kind of electromagnetic wave propagation in vacuum.

physics.gen-ph↗
arXiv1997

Faster Than Light ?

In this paper we present a pedestrian review of the theoretical fact that all relativistic wave equations possess solutions of arbitrary velocities $0 \leq v < \infty$. We discuss some experimental evidences of $v \geq c$ transmission of electromagnetic field configurations and the importance of these facts with regard to the principle of relativity.

physics.pop-ph↗
arXiv1997

The geometry of spacetime with superluminal phenomena

Recent theoretical results show the existence of arbitrary speeds (0 <= v < \infty) solutions of all relativistic wave equations. Some recent experiments confirm the results for sound waves. The question arises naturally: What is the appropriate geometry of spacetime to describe superluminal phenomena? In this paper we present a spacetime model that incorporates the valid results of Relativity Theory and yet describes coherently superluminal phenomena without paradoxes.

physics.class-ph↗
arXiv1997

Launching of Non-Dispersive Superluminal Beams

In this paper we analyze the physical meaning of sub- and superluminal soliton-like solutions (as the X-waves) of the relativistic wave equations and of some non-trivial solutions of the free Schrödinger equation for which the concepts of phase and group velocities have a different meaning than in the case of plane wave solutions. If we accept the strict validity of the principle of relativity, such solutions describe objects of two essentially different natures: carrying energy wave packets and inertia-free properly phase vibrations. Speeds of the first-type objects can exceed the plane wave velocity $c_*$ only inside media and are always less than the vacuum light speed $c$. Particularly, very fast sound pulses with speeds $c_* < v < c$ have already been launched. The second-type objects are incapable of carrying energy and information but have superluminal speed. If we admit the possibility of a breakdown of Lorentz invariance, pulses described, for example, by superluminal solutions of the Maxwell equations can be generated. Only experiment will give the final answer.

physics.class-ph↗
arXiv1996

On the Equation rotA = K A

We show that when correctly formulated the equation $\nabla \times \mbox{\boldmath $a$} = κ\mbox{\boldmath $a$}$ does not exhibit some inconsistencies atributed to it, so that its solutions can represent physical fields.

hep-th↗
arXiv1996

Spacetime model with superluminal phenomena

recent theoretical results show the existence of arbitrary speeds ($0\leq v <\infty$) solutions of the wave equations of mathematical physics. Some recent experiments confirm the results for sound waves. The question arises naturally: What is the appropriate spacetime model to describe superluminal phenomena? In this paper we present a spacetime model that incorporates the valid results of Relativity Theory and yet describes coherently superluminal phenomena without paradoxes.

gr-qc↗