<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">JMP</journal-id><journal-title-group><journal-title>Journal of Modern Physics</journal-title></journal-title-group><issn pub-type="epub">2153-1196</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/jmp.2018.93034</article-id><article-id pub-id-type="publisher-id">JMP-82712</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Physics&amp;Mathematics</subject></subj-group></article-categories><title-group><article-title>
 
 
  Discussion on the Energy Parallax and the Relationship to Perturbation Theory in Mathematical Physics
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Jean-Philippe</surname><given-names>Montillet</given-names></name><xref ref-type="aff" rid="aff1"><sub>1</sub></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib></contrib-group><aff id="aff1"><label>1</label><addr-line>ESPlab, Ecole Polytechnique de Lausanne, Neuch&amp;amp;acirc;tel, Switzerland</addr-line></aff><author-notes><corresp id="cor1">* E-mail:<email>jeanfi_montillet@yahoo.fr</email></corresp></author-notes><pub-date pub-type="epub"><day>31</day><month>01</month><year>2018</year></pub-date><volume>09</volume><issue>03</issue><fpage>479</fpage><lpage>499</lpage><history><date date-type="received"><day>29,</day>	<month>January</month>	<year>2018</year></date><date date-type="rev-recd"><day>25,</day>	<month>February</month>	<year>2018</year>	</date><date date-type="accepted"><day>28,</day>	<month>February</month>	<year>2018</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  This work is a discussion on the energy parallax theory developed in [1] [2] based on the multiplicity of the solutions theorem. This theory is compared with the perturbation theory in mathematical physics. The perturbation theory uses the increment of a solution which can be formalized with a Taylor series development. With the energy parallax theory, the convergence property of the Taylor series of the energy of a system is the key to decide to include additional solutions, defined on the so-called energy spaces [2]. The development is supported using various examples in quantum mechanics (i.e. Rayleigh-Schr
  &amp;#246;dinger perturbation theory) and wave theory with the Electromagnetic (EM) energy density (i.e. evanescent waves within the skin layer of a dielectric material). Finally, we discuss the Woodward effect [3] and the application of the energy parallax when assuming that the variations of EM energy density can trigger such effect within asymmetric cavities.
 
</p></abstract><kwd-group><kwd>Electromagnetism</kwd><kwd> Perturbation Theory</kwd><kwd> Energy Parallax</kwd><kwd> Quantum  Mechanics</kwd><kwd> Woodward Effect</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>1. Introduction</title><sec id="s1_1"><title>1.1. Work Overview</title><p>Perturbation theory has played an important role in the development of mathematics and physics from the end of the 19th century. With the pioneering work of H. Poincar&#233; in the theory of dynamical systems, the perturbation theory found a major application in the emergence of quantum mechanics with the preliminary works of M. Bore and W. Heisenberg [<xref ref-type="bibr" rid="scirp.82712-ref4">4</xref>] .</p><p>In quantum mechanics, perturbation theory generates states of a system that are adiabatically or linearly derived from a stable state. This stable state is generally an exact solution of the equations describing the system at hand. However, the system can be perturbed in a way that the exact solution, associated with the stable state, is no longer valid to model the changes in the system. Perturbation theory has been formulated in various domains, beyond quantum mechanics, using small quantities in order to describe the perturbed states, degenerated from the stable state. This perturbation shows up as a broadening of the initial energy quantity corresponding to the system in stable state [<xref ref-type="bibr" rid="scirp.82712-ref4">4</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref5">5</xref>] .</p><p>In previous works (i.e., [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref6">6</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] ), we define the Energy Spaces, which are subspaces of the Schwartz Space <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x2.png" xlink:type="simple"/></inline-formula> [<xref ref-type="bibr" rid="scirp.82712-ref8">8</xref>] associated with energy operators and generalized energy operators. This definition was used to define the concept of multiplicity of the solutions in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] (Theorem 2 and Corollary 1). The idea is to consider those energy spaces and functions associated with them when solving linear Partial Differential Equations (PDEs). More precisely, we look for solutions of a nominated linear PDE within those energy spaces. The concept was further developed using the Taylor series of the energy of a solution <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x3.png" xlink:type="simple"/></inline-formula> for a nominated PDE. The work was based on finding when the successive derivatives, defined through the Taylor series coefficients, are also solutions of this particular PDE (see Section 4 in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] ). The work was then generalized, considering <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x4.png" xlink:type="simple"/></inline-formula> (m in<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x5.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x6.png" xlink:type="simple"/></inline-formula>) [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] using the properties for the Sobolev spaces, the Schwartz space and the L2-norm. The concept of energy parallax was also introduced based on Theorem 3.</p><p>This work is a discussion between the energy parallax and the perturbation theory developed in quantum mechanics. In the next section, we recall this theory. An overview of the energy parallax together with the formal theory developed in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] using the properties of the Schwartz space <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x7.png" xlink:type="simple"/></inline-formula> and the L2 space, is briefly exposed at the beginning of Section 3. Through several examples, we discuss the similarities between the two theories. Finally, Section 5 is a discussion on the application of the energy parallax in the derivation of the Woodward effect for the special case of the asymmetric cavities. A conclusion ends this work.</p></sec><sec id="s1_2"><title>1.2. Notation and Symbols</title><p>In this work, several symbols are used. The set of integer numbers <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x8.png" xlink:type="simple"/></inline-formula> is sometimes called only for the positive integer such as <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x9.png" xlink:type="simple"/></inline-formula> or <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x10.png" xlink:type="simple"/></inline-formula> (for a space with dimension m). When the integer 0 is not included, it is explicitly mentioned such as<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x11.png" xlink:type="simple"/></inline-formula>. The set of natural numbers is<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x12.png" xlink:type="simple"/></inline-formula>, with only the positive numbers defined as<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x13.png" xlink:type="simple"/></inline-formula>. <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x14.png" xlink:type="simple"/></inline-formula>is the set of real numbers. Also, in this paper, the Schwartz space is called <inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x15.png" xlink:type="simple"/></inline-formula> which is the notation used in previous works such as [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] and [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] . Several notations describe the relationship between spaces such as intersection (<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x16.png" xlink:type="simple"/></inline-formula>), union (<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x17.png" xlink:type="simple"/></inline-formula>), inclusion (<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x18.png" xlink:type="simple"/></inline-formula>, inclusion without the equality<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x19.png" xlink:type="simple"/></inline-formula>, inclusion with equality<inline-formula><inline-graphic xlink:href="/html.scirp.org/file/13-7503406x19.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x20.png" xlink:type="simple"/></inline-formula>). Readers can refer to [<xref ref-type="bibr" rid="scirp.82712-ref9">9</xref>] or advanced mathematical textbooks for more explanations.</p></sec></sec><sec id="s2"><title>2. An Overview of Perturbation Theory and the Application in Quantum Mechanics</title><p>Following [<xref ref-type="bibr" rid="scirp.82712-ref4">4</xref>] , we can consider a simple problem with, let us say, a natural system<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula>, initial state <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula> and small perturbation<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula>, such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x24.png" xlink:type="simple"/></inline-formula>. Knowing that the system can evolve (or be perturbed) with incremental quantities, the general idea is to model these different states of the system. For example, we can model the next state as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x24.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x25.png" xlink:type="simple"/></inline-formula> with some assumptions such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x24.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x25.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x26.png" xlink:type="simple"/></inline-formula> (i.e.<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x24.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x25.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x26.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x27.png" xlink:type="simple"/></inline-formula>). We can then model the i-th phase of the system with the perturbation<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x21.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x22.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x23.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x24.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x25.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x26.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x27.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x28.png" xlink:type="simple"/></inline-formula>. Note that the perturbation theory can be applied to the variations of the system’s energy or solutions describing the system’s evolution.</p><p>However, perturbation theory can only estimate solution close to the exact solution. The addition of the small quantities to the exact solution can be expressed in (power) series (i.e. Taylor series around a nominated quantity―time, position in space, ... ). If the quantity becomes large, the series can diverge and the resulting solution is not valid to describe the perturbed system. In the example of our simple system described above, we have the condition that it exists N in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x29.png" xlink:type="simple"/></inline-formula> such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x29.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x30.png" xlink:type="simple"/></inline-formula>. The various perturbations of the system can then be written such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x29.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x30.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x31.png" xlink:type="simple"/></inline-formula>. In other words, the perturbation theory applied to our simple system is expressed through the series<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x29.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x30.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x31.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x32.png" xlink:type="simple"/></inline-formula>. This series may converge or not. The convergence/divergence properties in the perturbation theory is an important research topic [<xref ref-type="bibr" rid="scirp.82712-ref10">10</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref11">11</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref12">12</xref>] . Note that the intermediate states of the system are called degenerated states.</p><p>In quantum mechanics, those states are associated with intermediate levels of energy. These intermediate states are also solving the equations describing the system [<xref ref-type="bibr" rid="scirp.82712-ref5">5</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref13">13</xref>] . For example, let us recall the Rayleigh-Schr&#246;dinger perturbation theory. The system is described by the Hamiltonian operator (H) and the solutions describing the different states of the system are the eigenfunctions (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula>) of H. In fact, we have the famous relationship between the Hamiltonian, the eigenfunctions and the corresponding energy states (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x34.png" xlink:type="simple"/></inline-formula>),<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x35.png" xlink:type="simple"/></inline-formula> [<xref ref-type="bibr" rid="scirp.82712-ref13">13</xref>] . Thus, the perturbation in the system is described with a term V such as the Hamiltonian is also changed with<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x35.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x36.png" xlink:type="simple"/></inline-formula>. <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x35.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x36.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x37.png" xlink:type="simple"/></inline-formula>is the small quantity varying in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x33.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x34.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x35.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x36.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x37.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x38.png" xlink:type="simple"/></inline-formula>. The power series of the eigenfunction at the n-th order</p><p>perturbation can be written such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x39.png" xlink:type="simple"/></inline-formula> and the associated energy<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x39.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x40.png" xlink:type="simple"/></inline-formula>. The formula of <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x39.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x40.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x41.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x39.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x40.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x41.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x42.png" xlink:type="simple"/></inline-formula> are called the Lindset series for a</p><p>Hamiltonian operator driven by small perturbations [<xref ref-type="bibr" rid="scirp.82712-ref14">14</xref>] . Thus, there is a linear relationship between the degenerate states <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x43.png" xlink:type="simple"/></inline-formula> and the associated small energy quantity<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x43.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x44.png" xlink:type="simple"/></inline-formula>. Finally, the energy quantities and the associated eigenstates can be directly related to the total energy of the system <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x43.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x44.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x45.png" xlink:type="simple"/></inline-formula> and its associated eigenfunction <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x43.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x44.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x45.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x46.png" xlink:type="simple"/></inline-formula> such as [<xref ref-type="bibr" rid="scirp.82712-ref13">13</xref>] :</p><disp-formula id="scirp.82712-formula139"><label>(1)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x47.png"  xlink:type="simple"/></disp-formula><p>It is important to recall for the following that the perturbations for integrable Hamiltonian system are described by the Kolmogorov-Arnold-Moser (KAM) theorem [<xref ref-type="bibr" rid="scirp.82712-ref14">14</xref>] . The KAM theorem deals with persistence, under perturbation, of quasi-periodic motions in Hamiltonian dynamical systems.</p></sec><sec id="s3"><title>3. Energy Parallax and relationship with Perturbation Theory</title><p>This section starts with a short summary of the energy space theory, which defines the energy parallax. Readers can refer to [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref6">6</xref>] for a comprehensive description of the work. The second part discusses about the common features with the perturbation theory through some examples.</p><sec id="s3_1"><title>3.1. Short Review of the Energy Parallax</title><p>The concept of multiplicity of the solutions was developed in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] which is based on the theory of energy operators in the Schwartz space <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x48.png" xlink:type="simple"/></inline-formula> and some subspaces called energy spaces first defined in [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] and subsequently in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] . The main idea is to look for solutions of a given linear PDE in those subspaces. The theory has been recently extended (e.g., [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] ) in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x48.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x49.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x48.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x49.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x50.png" xlink:type="simple"/></inline-formula>) using the theory of Sobolev spaces, and in a special case the Hilbert spaces. In [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] , the author uses the Sobolev embedding theorem in order to show the Theorem 3 and the concept of multiplicity of the solutions.</p><p>Furthermore, the author defines in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] the concept of energy parallax, in order to understand the physical meaning of including additional solutions when varying the energy of a predefined system locally by taking into account additional smaller quantities. It is equivalent to take into account solutions in other energy subspaces (e.g., Theorem 3, [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] ).</p><p>To recall [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] , a possible application of the theory of the energy operators is to look at solutions of a given partial differential equation for solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula> of the form<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula>. Instead of solving the equation for specific values (e.g., boundary conditions), the work in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] (e.g., Theorem 2 and corollary) defines the concept of multiplicity of the solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula>) such as the study of the multiple solutions of a PDE based on the definition of the energy spaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula>). One way to understand this concept, is to study the convergence of the development in Taylor series of the energy function associated with a nominated energy space. It was shown in [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] that taking into account additional terms of the Taylor series leads to define additional solutions of the wave equation (see Section 4 [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] ). It was further generalized in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] (Section 5) with <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x58.png" xlink:type="simple"/></inline-formula>) and the solutions in the subspaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x58.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x59.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x58.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x59.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x60.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x58.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x59.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x60.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x61.png" xlink:type="simple"/></inline-formula>). Note that the inclusion of the energy subspaces is shown in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] using the properties of the Sobolev spaces. The energy spaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x51.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x52.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x53.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x54.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x55.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x56.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x57.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x58.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x59.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x60.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x61.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x62.png" xlink:type="simple"/></inline-formula> are defined following [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] (Definition 3).</p><p>Definition 1. [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] : The energy space<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x63.png" xlink:type="simple"/></inline-formula>, with p in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x63.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x64.png" xlink:type="simple"/></inline-formula>, is equal to<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x63.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x64.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x65.png" xlink:type="simple"/></inline-formula>. with <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x63.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x64.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x65.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x66.png" xlink:type="simple"/></inline-formula> for v in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x63.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x64.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x65.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x66.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x67.png" xlink:type="simple"/></inline-formula> defined as</p><disp-formula id="scirp.82712-formula140"><label>(2)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x68.png"  xlink:type="simple"/></disp-formula><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x69.png" xlink:type="simple"/></inline-formula>is a generalized energy operator defined in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] . In order to understand the notation, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x70.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x70.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x71.png" xlink:type="simple"/></inline-formula>and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x69.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x70.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x71.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x72.png" xlink:type="simple"/></inline-formula>. Now, let us define any PDEs of the form:</p><disp-formula id="scirp.82712-formula141"><label>(3)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x73.png"  xlink:type="simple"/></disp-formula><p>Thus, all the solutions are here defined in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula>. Now, we are interested in the solutions which can be defined on the energy spaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula>). In other words,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula>. In particular, we choose the solution<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula>. Furthermore, one can define <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula>, such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x80.png" xlink:type="simple"/></inline-formula> for<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x80.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x81.png" xlink:type="simple"/></inline-formula>. In other words, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x80.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x81.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x82.png" xlink:type="simple"/></inline-formula>and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x80.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x81.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x82.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x83.png" xlink:type="simple"/></inline-formula>, such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x74.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x75.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x76.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x77.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x78.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x79.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x80.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x81.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x82.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x83.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x84.png" xlink:type="simple"/></inline-formula>.</p><p>The theorem of (Multiplicity of Solutions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x85.png" xlink:type="simple"/></inline-formula>) stated in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] (Theorem 3) is:</p><p>Theorem 1. If <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x86.png" xlink:type="simple"/></inline-formula> is a subspace of all the solutions of a nominated linear PDE. For<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x86.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x87.png" xlink:type="simple"/></inline-formula>, g is in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x86.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x87.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x88.png" xlink:type="simple"/></inline-formula>. Then, g is a solution for this linear PDE if and only if:</p><p>1) (General condition to be a solution)<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x89.png" xlink:type="simple"/></inline-formula>.</p><p>2) (Solutions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x90.png" xlink:type="simple"/></inline-formula>)<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x90.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x91.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x90.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x91.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x92.png" xlink:type="simple"/></inline-formula>such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x90.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x91.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x92.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x93.png" xlink:type="simple"/></inline-formula>.</p><p>3) (Multiplicity of the solutions) If <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula>),<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula>and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula>, such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x98.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x98.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x99.png" xlink:type="simple"/></inline-formula>) and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x98.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x99.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x100.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x98.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x99.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x100.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x101.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x94.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x95.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x96.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x97.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x98.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x99.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x100.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x101.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x102.png" xlink:type="simple"/></inline-formula>.</p><p>4) (Superposition of solutions and energy conservation ) If<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x103.png" xlink:type="simple"/></inline-formula>, with <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x103.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x104.png" xlink:type="simple"/></inline-formula> such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x103.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x104.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x105.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x103.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x104.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x105.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x106.png" xlink:type="simple"/></inline-formula>), then<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x103.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x104.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x105.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x106.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x107.png" xlink:type="simple"/></inline-formula>.</p><p>Readers can refer to the appendices in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] for further information on the energy space theory. Note that, in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] , the theorem on the multiplicity of the solutions was established for the function of finite energy in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x108.png" xlink:type="simple"/></inline-formula> (m in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x108.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x109.png" xlink:type="simple"/></inline-formula>). [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] generalizes the same theorem for m in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x108.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x109.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x110.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x108.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x109.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x110.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x111.png" xlink:type="simple"/></inline-formula>), thanks to the theory of Sobolev Spaces.</p><p>Furthermore, let us recall a proposition first stated in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] (i equal 1) and generalized (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x112.png" xlink:type="simple"/></inline-formula>)) in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] .</p><p>Proposition 1. If for<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x114.png" xlink:type="simple"/></inline-formula>and analytic; for any <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x114.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x115.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x114.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x115.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x116.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x114.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x115.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x116.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x117.png" xlink:type="simple"/></inline-formula>), and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x113.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x114.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x115.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x116.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x117.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x118.png" xlink:type="simple"/></inline-formula> is analytic, where</p><disp-formula id="scirp.82712-formula142"><label>(4)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x119.png"  xlink:type="simple"/></disp-formula><p>then</p><disp-formula id="scirp.82712-formula143"><label>(5)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x120.png"  xlink:type="simple"/></disp-formula><p>is a convergent series.</p></sec><sec id="s3_2"><title>3.2. Examples and Discussion between the Energy Parallax and the Perturbation Theory</title><p>In areas where the solutions are described via a set of PDEs, the perturbation theory can be rather complicated to use. Instead, the energy parallax shows that the variations of energy quantity lead to define solutions according to the spaces associated with the energy quantities (or energy spaces as defined in Definition 1). Theorem 1―the multiplicity of the solutions―lays the basis to define the solutions associated with the perturbed system, every time the energy increases in small quantities. Let us recall the definition of energy parallax [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] (Definition 4):</p><p>Definition 2. Considering a linear PDE with some solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula> such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula>. Furthermore, if it exists p and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula> such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula>, then we associate the energy <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula> for <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula>, such as one can estimate the variation <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula> over an elementary quantity <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula> (e.g., space, time or space-time for the specific case m in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula>). If <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x130.png" xlink:type="simple"/></inline-formula> is not negligible (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x130.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x131.png" xlink:type="simple"/></inline-formula>such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x130.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x131.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x132.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x130.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x131.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x132.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x133.png" xlink:type="simple"/></inline-formula>), then one can consider additional solutions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x121.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x122.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x123.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x124.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x125.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x126.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x127.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x128.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x129.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x130.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x131.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x132.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x133.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x134.png" xlink:type="simple"/></inline-formula>.</p><p>The validity of this approach is only guaranteed if the power series of the energy is converging. The convergence properties is essential, because of the assumptions of small variations of energy. Due to those small energy variations, a limited number of energy subspaces are taken into account and thus a limited number of additional solutions are introduced in the considered system. This idea is written mathematically in the superposition of solutions and energy conservation, property 4 in Theorem 1. That is why the fundamental work in [<xref ref-type="bibr" rid="scirp.82712-ref6">6</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] focuses on the function of finite energy in the Schwartz space <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x135.png" xlink:type="simple"/></inline-formula> (m in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x135.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x136.png" xlink:type="simple"/></inline-formula>) in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] . <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x135.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x136.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x137.png" xlink:type="simple"/></inline-formula>is the L2 space associated with the 2-norm on<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x135.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x136.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x137.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x138.png" xlink:type="simple"/></inline-formula>.</p><p>To illustrate the energy parallax, let us come back to our simple system example used in the explaination of the perturbation theory. The energy of this system <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x139.png" xlink:type="simple"/></inline-formula> increases slowly such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x139.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x140.png" xlink:type="simple"/></inline-formula>. If we assume that the space of</p><p>the solutions of PDEs describing this system is<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x141.png" xlink:type="simple"/></inline-formula>. We can then assume that if<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x141.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x142.png" xlink:type="simple"/></inline-formula>, the power series</p><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x143.png" xlink:type="simple"/></inline-formula>is convergent. <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x143.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x144.png" xlink:type="simple"/></inline-formula>depends on the variables of<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x143.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x144.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x145.png" xlink:type="simple"/></inline-formula>. In the classical formulation of a Taylor series with a function depending on time, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x143.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x144.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x145.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x146.png" xlink:type="simple"/></inline-formula>and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x143.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x144.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x145.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x146.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x147.png" xlink:type="simple"/></inline-formula> is some initial time/coordinate where the development is realized.</p><p>Let us consider that <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula> is equal to<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula>. Now, applying Proposition 1, the power series <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula> is convergent. Knowing that <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula>) (i.e. Proposition 1 ), the definition of the energy space recalls that the solutions<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula>. The energy parallax with Theorem 1 states the conditions when the solutions of the form <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula>) are also solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x156.png" xlink:type="simple"/></inline-formula> (or<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x156.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x157.png" xlink:type="simple"/></inline-formula>). The general idea is that when the energy of the system increases of a small quantity (i.e.<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x156.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x157.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x158.png" xlink:type="simple"/></inline-formula>), one can look at solutions with higher derivatives (i.e.<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x156.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x157.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x158.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x159.png" xlink:type="simple"/></inline-formula>) belonging to<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x148.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x149.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x150.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x151.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x152.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x153.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x154.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x155.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x156.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x157.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x158.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x159.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x160.png" xlink:type="simple"/></inline-formula>.</p><p>Let remind us of an example in functional analysis first shown in [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] in order to illustrate the energy parallax.</p><sec id="s3_2_1"><title>3.2.1. Example 1: Specific Solutions of the Wave equation in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x161.png" xlink:type="simple"/></inline-formula></title><p>As a simple case of linear PDE, the wave equation with the particular solutions of the form of evanescent waves, was already discussed in Section 6 of [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] and [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] . However, it is an interesting example to apply and understand the concept of multiplicity of the solutions stated in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] (e.g., Theorem 3) and recall in Theorem 1. From [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] , the wave equation can be formulated in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x162.png" xlink:type="simple"/></inline-formula> (with t and r the time and space variables):</p><disp-formula id="scirp.82712-formula144"><label>(6)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x163.png"  xlink:type="simple"/></disp-formula><p>c is the speed of light. Note that the values of t and r are restricted to some interval, because it is conventional to solve the equation for a restricted time interval in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x164.png" xlink:type="simple"/></inline-formula> and a specific region in space. According to the previous section, here we are interested in the solutions in the energy (sub)space<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x164.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x165.png" xlink:type="simple"/></inline-formula>, of the kind</p><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x166.png" xlink:type="simple"/></inline-formula>(n in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x166.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x167.png" xlink:type="simple"/></inline-formula>, p in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x166.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x168.png" xlink:type="simple"/></inline-formula>, k in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x166.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x168.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x169.png" xlink:type="simple"/></inline-formula>). Furthermore, the relationship <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x166.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x167.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x168.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x169.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x170.png" xlink:type="simple"/></inline-formula> imposes that the solutions should be</p><p>finite energy functions, decaying for large values of r and t. It was previously underlined in [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] that planar waves should be rejected, because this type of</p><p>solution does not belong to<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x171.png" xlink:type="simple"/></inline-formula>. However, evanescent waves are a type of solutions included in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x171.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x172.png" xlink:type="simple"/></inline-formula> and considered in this work. They are here defined such as:</p><disp-formula id="scirp.82712-formula145"><label>(7)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x173.png"  xlink:type="simple"/></disp-formula><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula>and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula> are the wave numbers, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula>is the angular frequency and A is the amplitude of this wave [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . Assuming <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula> and (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula>) known, one can add some boundary conditions in order to estimate<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula>and A. Furthermore, a traveling wave solution of (6) should satisfy the dispersion relationship between<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x183.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x183.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x184.png" xlink:type="simple"/></inline-formula>and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x183.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x184.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x185.png" xlink:type="simple"/></inline-formula> [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . However, our interest is just the general form assuming that all the parameters are known. For<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x183.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x184.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x185.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x186.png" xlink:type="simple"/></inline-formula>, the type of solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x174.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x175.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x176.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x177.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x178.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x179.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x180.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x181.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x182.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x183.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x184.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x185.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x186.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x187.png" xlink:type="simple"/></inline-formula> are:</p><disp-formula id="scirp.82712-formula146"><label>(8)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x188.png"  xlink:type="simple"/></disp-formula><p>In<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x189.png" xlink:type="simple"/></inline-formula>, one can then write the type of solutions</p><disp-formula id="scirp.82712-formula147"><label>(9)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x190.png"  xlink:type="simple"/></disp-formula><p>Let us consider the form of solutions which propagates in a closed cavity (e.g., closed wave guide [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] ). One possible solution is the evanescent wave described in (7). Now, if f and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula> are analytic in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula>, it was shown (see Proposition 1 in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] and Proposition 1) that f is finite energy (and more generally in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula>) with a wise choice on the parameters A, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula>and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x196.png" xlink:type="simple"/></inline-formula>. One can estimate the difference of energy in time over <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x196.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x197.png" xlink:type="simple"/></inline-formula> inside the cavity at a specific location <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x196.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x197.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x198.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x196.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x197.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x198.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x199.png" xlink:type="simple"/></inline-formula>in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x191.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x192.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x193.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x194.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x195.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x196.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x197.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x198.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x199.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x200.png" xlink:type="simple"/></inline-formula>) such as</p><disp-formula id="scirp.82712-formula148"><label>(10)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x201.png"  xlink:type="simple"/></disp-formula><p>Here the symbol “<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x202.png" xlink:type="simple"/></inline-formula>” means that</p><disp-formula id="scirp.82712-formula149"><label>(11)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x203.png"  xlink:type="simple"/></disp-formula><p>Now, let us do a hypothesis that <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x204.png" xlink:type="simple"/></inline-formula> increases significantly over <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x204.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x205.png" xlink:type="simple"/></inline-formula> modifying the approximation in (11)</p><disp-formula id="scirp.82712-formula150"><label>(12)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x206.png"  xlink:type="simple"/></disp-formula><p>and then,</p><disp-formula id="scirp.82712-formula151"><label>(13)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x207.png"  xlink:type="simple"/></disp-formula><p>To recall that<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x208.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x208.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x209.png" xlink:type="simple"/></inline-formula>and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x208.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x209.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x210.png" xlink:type="simple"/></inline-formula>, and using Theorem 1, one can take into account solutions in those (energy) subspaces. The multiplicity of the solutions (i.e., Theorem 1), due to the variation of energy, can be formulated as an approximation for taking into account additional solutions produced by the wave equation.</p><p>Discussion (1): With the above example, we can now expose some common features between the energy parallax formulation and the perturbation theory. Firstly, one can emphasize the Lindset series of the energy (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x211.png" xlink:type="simple"/></inline-formula>) and the eigenfunctions (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x211.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x212.png" xlink:type="simple"/></inline-formula>) described in Section 2. To recall Section 3.2, the energy parallax theory uses the Taylor Series development of a general solution</p><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x213.png" xlink:type="simple"/></inline-formula>for a given PDE (with<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x213.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x214.png" xlink:type="simple"/></inline-formula>) associated with the Taylor Series</p><p>of the corresponding energy<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x215.png" xlink:type="simple"/></inline-formula>. In quantum mechanics, perturbation theory relies on the Hermitian properties of the Hamiltonian, which establish the relationship between the energy states and the eigenfunctions. However, the energy parallax theory is not based on an explicit operator, which establishes a direct relationship between the energy increments and the perturbation of the general solution.</p><p>The energy spaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x216.png" xlink:type="simple"/></inline-formula> (p and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x216.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x217.png" xlink:type="simple"/></inline-formula>) together with the Theorem 1 describe how the perturbation in the power series of the energy leads to consider additional solutions based on the higher order derivatives of the primary (original) solution. Technically, we showed in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] the inclusion of the energy (sub)spaces (i.e., <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x216.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x217.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x218.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x216.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x217.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x218.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x219.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x216.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x217.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x218.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x219.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x220.png" xlink:type="simple"/></inline-formula>) similar to the Sobolev embedding theorem (see [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] , Properties 2). Unlike the perturbation theory where the solutions are expressed in power series with the addition of small quantities to take into account the perturbation of the system’s energy, the energy parallax considers additional solutions to a given PDE (or PDEs describing a given system) based on the higher order derivatives of the primary solution when considering higher order perturbations of the system’s energy.</p><p>Note that our formulation of the energy parallax is at the moment restricted to functions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x221.png" xlink:type="simple"/></inline-formula>, and thus finite energy function. Thus, every function (general solution of the PDE, additional solutions defined on the energy spaces, superposition of all the solutions) should be finite energy function to guarantee that they are in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x221.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x222.png" xlink:type="simple"/></inline-formula> [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] .</p></sec><sec id="s3_2_2"><title>3.2.2. Example 2: Application to EM Field Theory</title><p>Perturbation theory may be difficult to implement when the system is described by a set of PDEs. One area in particular is the area of field theory such as Electro Magnetic (EM) field with EM waves as solutions of those PDEs. The term field is first coined by M. Faraday in 1849. The work of J. C. Maxwell leaded to the discovery of the propagation of EM waves [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . A turning point is the introduction of the special theory of relativity by. A. Einstein in 1905 with no longer relationship between the speed of the observer and the velocity of the waves. Field theory becomes even more important with the development of quantum mechanics in the late 1920s and the work of P. Dirac using the emerging theory of quantum field theory to explain the energy decay of an atom between different quantum states [<xref ref-type="bibr" rid="scirp.82712-ref16">16</xref>] .</p><p>Let us recall an example of variation of EM energy density in the skin layer of a conductor. The theory of energy space is now applied to the possible variations of electromagnetic energy density due to, for example, skin depth effect [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] inside some conductive material. Beyond this application, the interest is to give a physical meaning of taking into account those additional solutions in various energy spaces. Thus, let us formulate the variation in time of energy density (u) at the second order with a Taylor series development such as:</p><disp-formula id="scirp.82712-formula152"><label>(14)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x223.png"  xlink:type="simple"/></disp-formula><p>o is the Landau notation to omit higher order quantities. Note that at the first order<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x224.png" xlink:type="simple"/></inline-formula>. The higher order terms are based on the assumptions that the</p><p>EM waves inside the skin layer of the copper plate are evanescent waves and thus functions in the Schwartz space (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula>―with 3 dimension variables and considering also the time ) [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . As discussed before, those solutions are finite energy functions and in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x226.png" xlink:type="simple"/></inline-formula> (i.e. following [<xref ref-type="bibr" rid="scirp.82712-ref1">1</xref>] and [<xref ref-type="bibr" rid="scirp.82712-ref7">7</xref>] , <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x226.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x227.png" xlink:type="simple"/></inline-formula> at some given point in the skin layer defined by the coordinates<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x226.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x227.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x228.png" xlink:type="simple"/></inline-formula>). To recall Section 2, the definition of the energy space<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x226.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x227.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x228.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x229.png" xlink:type="simple"/></inline-formula>, we can state in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x225.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x226.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x227.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x228.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x229.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x230.png" xlink:type="simple"/></inline-formula></p><disp-formula id="scirp.82712-formula153"><label>(15)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x231.png"  xlink:type="simple"/></disp-formula><p>Here f is either the electric or magnetic field (i.e. the absolute norm of <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x232.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x232.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x233.png" xlink:type="simple"/></inline-formula> respectively). With the concept of multiplicity of the solutions (e.g., Theorem 1). If g is a general solution of some linear PDEs, then <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x232.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x233.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x234.png" xlink:type="simple"/></inline-formula> can be identified as a special form of the solution (conditionally to its existence ).</p><p>Now considering the wave equation, the electric field and magnetic fields are solutions and belong to the subspace <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula> and associated with the variation of energy density<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula>. Furthermore, we can consider the solutions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula> associated with the variation of energy density<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula>, which can be explained with the concept of multiplicity of the solutions. The solutions of interest in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x239.png" xlink:type="simple"/></inline-formula> are for the electric field <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x239.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x240.png" xlink:type="simple"/></inline-formula> and the magnetic field<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x239.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x240.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x241.png" xlink:type="simple"/></inline-formula>. The Taylor Series development of the energy of (for example) the electric field on a nominated position in space (i.e.,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x239.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x240.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x241.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x242.png" xlink:type="simple"/></inline-formula>) and in an increment of time<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x235.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x236.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x237.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x238.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x239.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x240.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x241.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x242.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x243.png" xlink:type="simple"/></inline-formula>:</p><disp-formula id="scirp.82712-formula154"><label>(16)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x244.png"  xlink:type="simple"/></disp-formula><p>Finally one can write the relationship with the energy density following (14) and the previous Taylor series development for the electric and/or magnetic field:</p><disp-formula id="scirp.82712-formula155"><label>(17)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x245.png"  xlink:type="simple"/></disp-formula><p>Therefore, taking into account the second order term of the energy density <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x246.png" xlink:type="simple"/></inline-formula> means that additional solutions should also be considered in the EM modeling.</p></sec><sec id="s3_2_3"><title>3.2.3. Example 3: Variation of EM Energy density―consequences from thewave theory Point of View</title><p>We are taking the example of the variation of EM energy density inside a copper wall due to planar waves reflecting and refracting on it [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . To recall the previous example, the EM field is now including (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula>) and (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula>), contribution of the subspaces <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x252.png" xlink:type="simple"/></inline-formula> respectively when using the concept of multiplicity of the solutions (i.e. Theorem 1) for the higher order derivatives of the energy density (see (14)). We call the total EM field <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x252.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x253.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x252.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x253.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x254.png" xlink:type="simple"/></inline-formula> inside the copper plate (skin layer) with associated permittivity <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x252.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x253.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x254.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x255.png" xlink:type="simple"/></inline-formula> and permeability<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x247.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x248.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x249.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x250.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x251.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x252.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x253.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x254.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x255.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x256.png" xlink:type="simple"/></inline-formula>. They are solutions of the Maxwell equations:</p><disp-formula id="scirp.82712-formula156"><label>(18)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x257.png"  xlink:type="simple"/></disp-formula><p>with the principle of charge conservation:</p><disp-formula id="scirp.82712-formula157"><label>(19)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x258.png"  xlink:type="simple"/></disp-formula><p>Now, the variation of energy density (14) together with the equation of charge conservation is formulated such as:</p><disp-formula id="scirp.82712-formula158"><label>(20)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x259.png"  xlink:type="simple"/></disp-formula><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula>is the Poynting vector. Now, writing<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x261.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x261.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x262.png" xlink:type="simple"/></inline-formula>and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x261.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x262.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x263.png" xlink:type="simple"/></inline-formula> is the first derivative in time (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x261.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x262.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x263.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x264.png" xlink:type="simple"/></inline-formula>) (i.e. solutions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x260.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x261.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x262.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x263.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x264.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x265.png" xlink:type="simple"/></inline-formula>), then following [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>]</p><disp-formula id="scirp.82712-formula159"><label>(21)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x266.png"  xlink:type="simple"/></disp-formula><p>using the equalities <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x267.png" xlink:type="simple"/></inline-formula> and the Maxwell equation<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x267.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x268.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x267.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x268.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x269.png" xlink:type="simple"/></inline-formula>the previous equation reduces to:</p><disp-formula id="scirp.82712-formula160"><label>(22)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x270.png"  xlink:type="simple"/></disp-formula><p>We can separate in three groups,</p><disp-formula id="scirp.82712-formula161"><graphic  xlink:href="//html.scirp.org/file/13-7503406x271.png"  xlink:type="simple"/></disp-formula><p>The Poynting vector is defined as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x272.png" xlink:type="simple"/></inline-formula> and its derivative <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x272.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x273.png" xlink:type="simple"/></inline-formula>. Thus, the second order term of the energy density is the contribution of the EM field generated by <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x272.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x273.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x274.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x272.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x273.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x274.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x275.png" xlink:type="simple"/></inline-formula> is:</p><disp-formula id="scirp.82712-formula162"><graphic  xlink:href="//html.scirp.org/file/13-7503406x276.png"  xlink:type="simple"/></disp-formula><p>The last line is the contribution from only the fields <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x277.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x277.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x278.png" xlink:type="simple"/></inline-formula>.</p><p>Finally, the creation of the wave defined by the EM field (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x280.png" xlink:type="simple"/></inline-formula>) means that some material properties may allow to create two type of EM waves namely (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x280.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x281.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x280.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x281.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x282.png" xlink:type="simple"/></inline-formula>) and (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x280.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x281.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x282.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x283.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x279.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x280.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x281.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x282.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x283.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x284.png" xlink:type="simple"/></inline-formula>).</p></sec></sec></sec><sec id="s4"><title>4. Some Comments on the Uncertainty Principle in the Energy Parallax Theory</title><p>Uncertainty principle is generally known from the Heisenberg’s relationship in quantum mechanics. In a broad sense, uncertainty principles are a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties describing a system, known as complimentary variables (e.g. position and momentum of a particle), can be known [<xref ref-type="bibr" rid="scirp.82712-ref5">5</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref13">13</xref>] .</p><p>So far in our comparison between the energy parallax and the perturbation theory, the development is based on the mathematical properties of the functions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x285.png" xlink:type="simple"/></inline-formula> (i.e. finite energy functions) in order to guaranty the convergence of the (Taylor) series associated with those functions and/or the energy. In particular, some examples uses special type of waves (i.e. evanescent waves in Section 3.2.1 or Section 3.2.2) included in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x285.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x286.png" xlink:type="simple"/></inline-formula> with the application of the energy parallax on the variation of EM energy density. Thus, we emphasize that the energy function and/or the EM energy density defined for functions in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x285.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x286.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x287.png" xlink:type="simple"/></inline-formula>, play a key role in both the energy parallax and perturbation theory. Here, we show with the uncertainty principles, how the variables in our system (i.e. time, frequency, wavelength) can be affected with the variations of energy quantities.</p><p>Let us define the electric field E function in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x288.png" xlink:type="simple"/></inline-formula> with variables in time t and space x. Following the definition of<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x288.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x289.png" xlink:type="simple"/></inline-formula>, one can write</p><disp-formula id="scirp.82712-formula163"><label>(23)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x290.png"  xlink:type="simple"/></disp-formula><p>defining <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x291.png" xlink:type="simple"/></inline-formula> and k the wavelength, we can further state using the Parseval-Dirichlet equality― [<xref ref-type="bibr" rid="scirp.82712-ref17">17</xref>] ,</p><disp-formula id="scirp.82712-formula164"><label>(24)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x292.png"  xlink:type="simple"/></disp-formula><p>Associating the quantities <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x293.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x293.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x294.png" xlink:type="simple"/></inline-formula> with <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x293.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x294.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x295.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x293.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x294.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x295.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x296.png" xlink:type="simple"/></inline-formula> [<xref ref-type="bibr" rid="scirp.82712-ref17">17</xref>] , one can write the uncertainty principle in time and frequency,</p><disp-formula id="scirp.82712-formula165"><label>(25)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x297.png"  xlink:type="simple"/></disp-formula><p>with the relationship (modified Parseval-Dirichlet equality) <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x298.png" xlink:type="simple"/></inline-formula> inserted in (24), the uncertainty principle can be written differently</p><disp-formula id="scirp.82712-formula166"><label>(26)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x299.png"  xlink:type="simple"/></disp-formula><p>Thus, the variation of the energy quantity<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x300.png" xlink:type="simple"/></inline-formula>, means that the function/wave is distorted in time or an increase of the frequency spectrum. In terms of energy parallax, if we think about the superposition of multiple waves/functions (i.e. Theorem 1), the broadening of the frequency spectrum could be interpreted as additional waves with larger (or shifted) frequency bands.</p><p>Finally, if we want to look at the inequality involving the position x, one needs to use the wave-particle duality and consider the wave as a photon. In this case, we can use the Heisenberg uncertainty principle in quantum mechanics to state the relationship between x and the moment p [<xref ref-type="bibr" rid="scirp.82712-ref16">16</xref>] .</p></sec><sec id="s5"><title>5. Discussion on the Woodward Effect interpreted with the Energy Parallaxtheory</title><p>The Woodward effect, also referred to as a Mach effect, is part of a hypothesis proposed by James F. Woodward in 1990 [<xref ref-type="bibr" rid="scirp.82712-ref3">3</xref>] . The hypothesis states that transient mass fluctuations arise in any object that absorbs internal energy while undergoing a proper acceleration. Recently, the Woodward effect was applied to asymmetric EM cavities (i.e. frustum) due to EM waves reflected on the cavity's wall, and creating a momentum [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] . The assumption is that the EM energy density variation results from the evanescent waves taking place in the skin depth of the asymmetric EM cavity’s walls.</p><p>The Woodward effect is based on a formula which the author implicitly assumed that the rest mass of the piezoelectric material via the famous Einstein's relation in special relativity <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x301.png" xlink:type="simple"/></inline-formula> (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x301.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x302.png" xlink:type="simple"/></inline-formula>the rest energy associated with the rest mass m) and its variation via electrostrictive effect. In order to apply this formula to an asymmetric EM cavity, the author in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] formulated the hypothesis that the EM excitation on the walls creates electric charges (i.e. electrons) which makes the rest mass varying with time. The Woodward effect can be mathematically derived in various ways [<xref ref-type="bibr" rid="scirp.82712-ref18">18</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref19">19</xref>] [<xref ref-type="bibr" rid="scirp.82712-ref20">20</xref>] . Note that in the appendices, we also show a derivation based on the model of a point mass particle moving in a varying electric field.</p><p>If we define the mass density such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x303.png" xlink:type="simple"/></inline-formula>, then from [<xref ref-type="bibr" rid="scirp.82712-ref20">20</xref>] , one can write the elementary mass variation per unit of volume</p><disp-formula id="scirp.82712-formula167"><label>(27)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x304.png"  xlink:type="simple"/></disp-formula><p>Let us define the the rest energy<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x305.png" xlink:type="simple"/></inline-formula>, then</p><disp-formula id="scirp.82712-formula168"><label>(28)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x306.png"  xlink:type="simple"/></disp-formula><p>In some particular cases such as an EM cavity, we assume that the variation in time of the rest energy is equal to the variation of EM energy density u (i.e.<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x307.png" xlink:type="simple"/></inline-formula>), but the rest energy is much bigger than the EM energy density<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x307.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x308.png" xlink:type="simple"/></inline-formula>. It allows then to state the relationship between the Woodward effect and the EM energy density</p><disp-formula id="scirp.82712-formula169"><label>(29)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x309.png"  xlink:type="simple"/></disp-formula><p>The EM energy density u follows the general definition of the sum of energy density from the electric (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x310.png" xlink:type="simple"/></inline-formula>) and magnetic (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x310.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x311.png" xlink:type="simple"/></inline-formula>) fields [<xref ref-type="bibr" rid="scirp.82712-ref15">15</xref>] . Note that in [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] , the author defines the Electro magnetic and gravitational coupling using equation (29).</p><p>Discussion (2): The above equation shows that the variation of mass density is a linear relationship with the first and second derivative of the EM energy density. To recall Example 2 in Section 3.2.2, we underline the relationship between the order of the derivatives of the EM energy density and the energy spaces. As we are dealing with evanescent waves (functions in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x312.png" xlink:type="simple"/></inline-formula> with<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x312.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x313.png" xlink:type="simple"/></inline-formula>, with 3D space and time) in the skin layer of the EM cavity, we can apply the results of Example 2 with the multiplicity of the solutions (i.e. Theorem 1). The interpretation of the Woodward effect using the energy parallax is that the solutions are in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x312.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x313.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x314.png" xlink:type="simple"/></inline-formula> (k in<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x312.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x313.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x314.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x315.png" xlink:type="simple"/></inline-formula>) using the same definitions as in Section 2. In other words, we need to take into account the evanescent waves associated with the electric and magnetic fields and their first and second derivative in time.</p></sec><sec id="s6"><title>6. Conclusions</title><p>This work is a discussion on the energy parallax and the comparison with the perturbation theory. One of the motivation is that the energy parallax is based on the multiplicity of the solutions (i.e. Theorem 1) developed by [<xref ref-type="bibr" rid="scirp.82712-ref2">2</xref>] for the functions in the<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x316.png" xlink:type="simple"/></inline-formula>, i.e. finite energy functions in the Schwartz space<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x316.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x317.png" xlink:type="simple"/></inline-formula>. Unlike the perturbation theory where the solutions are expressed in power series with the addition of small quantities to take into account the perturbation of the system’s energy, the energy parallax considers additional solutions to a given PDE (or PDEs describing a given system) based on the higher order derivatives of the primary solution when considering higher order perturbations of the system’s energy. Note that we give some meaning to the variation of energy via the uncertainty inequality (time, frequency) based on the superposition of waves using the energy parallax.</p><p>The perturbation theory is well defined when the system can be described with an operator (e.g., Hamiltonian) such as in quantum mechanics. However, complex systems using multiple operators or various PDEs may be best described in terms of the variation of the total energy. In this way, the energy parallax can be seen as an alternative. In the first example, the energy parallax is applied to the evanescent waves in the skin layer of a dielectric material (i.e. EM fields). We also show the possible application of this concept with the Woodward effect for the special case of the asymmetrical cavities. The energy parallax is used with the higher order derivatives of the EM energy density.</p></sec><sec id="s7"><title>Acknowledgements</title><p>The authors would like to acknowledge people who have been involved in developing the presented model during the past two years via discussions or various feedbacks including Dr. Jos&#233; Rodal and Prof. Heidi Fearn (California State Fullerton University).</p></sec><sec id="s8"><title>Cite this paper</title><p>Montillet, J.-P. (2018) Discussion on the Energy Parallax and the Relationship to Perturbation Theory in Mathematical Physics. Journal of Modern Physics, 9, 479-499. https://doi.org/10.4236/jmp.2018.93034</p></sec><sec id="s9"><title>Appendix: Derivation of the Woodward Effect from a Point Mass Particle with a Varying Charge</title><p>In this section, we derive the Woodward effect for a particle moving along a world line in a varying electric field. It is a simplistic model of a so called “relativistic” capacitor, due to the variation of mass only dependent of the</p><p>variation of charge<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x318.png" xlink:type="simple"/></inline-formula>.</p>A1. Lagrangian Formalism<p>Let us call <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x320.png" xlink:type="simple"/></inline-formula>. Thus, we assume that the Lagrangian is a function of<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x320.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x321.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x320.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x321.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x322.png" xlink:type="simple"/></inline-formula>and the time t. Now, the action principle is applied when varying the fields of the small quantity <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x320.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x321.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x322.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x323.png" xlink:type="simple"/></inline-formula> and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x319.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x320.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x321.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x322.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x323.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x324.png" xlink:type="simple"/></inline-formula> The infinitesimally variation of the action is then</p><disp-formula id="scirp.82712-formula170"><label>(30)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x325.png"  xlink:type="simple"/></disp-formula><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x326.png" xlink:type="simple"/></inline-formula>is a proper interval defines along the path of the particle. In order to simplify the notation, let us define <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x326.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x327.png" xlink:type="simple"/></inline-formula> and<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x326.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x327.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x328.png" xlink:type="simple"/></inline-formula>. One can further develop the equation above</p><disp-formula id="scirp.82712-formula171"><label>(31)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x329.png"  xlink:type="simple"/></disp-formula><p>using the same development as the Euler-Lagrange equation (and the assumption that<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x330.png" xlink:type="simple"/></inline-formula>), one can rewrite the above equation such as</p><disp-formula id="scirp.82712-formula172"><label>(32)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x331.png"  xlink:type="simple"/></disp-formula><p>Note that the momentum <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x332.png" xlink:type="simple"/></inline-formula> is defined such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x332.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x333.png" xlink:type="simple"/></inline-formula>. Now, let us state the Euler-Lagrange equation</p><disp-formula id="scirp.82712-formula173"><label>(33)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x334.png"  xlink:type="simple"/></disp-formula>A2. The Case of the Point Mass Particle inside an Electric Field<p>The idea is to use the Lagrangian for a particle inside an EM field subject to a Lorentz force, but with a varying charge in time <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x335.png" xlink:type="simple"/></inline-formula> and a varying mass in time and space<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x335.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x336.png" xlink:type="simple"/></inline-formula>. Let us state the Lagrangian for such a system with simply the electric field (see for a full statement [<xref ref-type="bibr" rid="scirp.82712-ref21">21</xref>] ):</p><disp-formula id="scirp.82712-formula174"><label>(34)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x337.png"  xlink:type="simple"/></disp-formula><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x338.png" xlink:type="simple"/></inline-formula>is the electric potential such as<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x338.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x339.png" xlink:type="simple"/></inline-formula>. The system is not conservative (off-shell variation) and thus at the first order variation of the Lagrangian we can apply (32):</p><disp-formula id="scirp.82712-formula175"><label>(35)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x340.png"  xlink:type="simple"/></disp-formula><p>Knowing that<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x341.png" xlink:type="simple"/></inline-formula>, one can develop further</p><disp-formula id="scirp.82712-formula176"><label>(36)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x342.png"  xlink:type="simple"/></disp-formula><p>with the assumptions that<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula>,<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x347.png" xlink:type="simple"/></inline-formula>. Also with the approximation<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x347.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x348.png" xlink:type="simple"/></inline-formula>, <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x347.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x348.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x349.png" xlink:type="simple"/></inline-formula>Now, if we separate the variables as internal and external parameters, such as <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x347.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x348.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x349.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x350.png" xlink:type="simple"/></inline-formula> are external (or parameters in on-shell transformation); and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x343.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x344.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x345.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x346.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x347.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x348.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x349.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x350.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x351.png" xlink:type="simple"/></inline-formula> are the parameters due to the “relativistic” capacitor model. We can then rewrite (23) such as:</p><disp-formula id="scirp.82712-formula177"><label>(37)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x352.png"  xlink:type="simple"/></disp-formula><p>Thus, from this equation, we can see that the first group of terms in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x353.png" xlink:type="simple"/></inline-formula> and the second group of terms in <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x353.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x354.png" xlink:type="simple"/></inline-formula> are with derivatives of the external variables (e.g., <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x353.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x354.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x355.png" xlink:type="simple"/></inline-formula>, V), whereas the two last groups of variables are with derivatives of the internal variables (e.g., m, q). Now, if we assume that<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x353.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x354.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x355.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x356.png" xlink:type="simple"/></inline-formula>, in other words, a negligible displacement in space during the variation of<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x353.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x354.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x355.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x356.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x357.png" xlink:type="simple"/></inline-formula>, the equation becomes</p><disp-formula id="scirp.82712-formula178"><label>(38)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x358.png"  xlink:type="simple"/></disp-formula><p>and reciprocally with the assumption<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x359.png" xlink:type="simple"/></inline-formula>,</p><disp-formula id="scirp.82712-formula179"><label>(39)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x360.png"  xlink:type="simple"/></disp-formula><p>and by definition<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x361.png" xlink:type="simple"/></inline-formula>. One can set<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x361.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x362.png" xlink:type="simple"/></inline-formula>, and see the variation of mass only dependent of the variation of charge <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x361.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x362.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x363.png" xlink:type="simple"/></inline-formula> in our “relativistic” capacitor model. Furthermore, we can get the equation without variation of the internal variables if<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x361.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x362.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x363.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x364.png" xlink:type="simple"/></inline-formula>:<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x361.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x362.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x363.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x364.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x365.png" xlink:type="simple"/></inline-formula>.</p><p>As the “relativistic” capacitor model is a particle moving along a world line, one can follow the same way that Prof. Woodward used to establish the Woodward effect (See Appendix A of [<xref ref-type="bibr" rid="scirp.82712-ref3">3</xref>] ). Let us write the equation of the momentum when the particle is stimulated by external force:<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x366.png" xlink:type="simple"/></inline-formula>. With equation (39), one can write:</p><disp-formula id="scirp.82712-formula180"><label>(40)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x367.png"  xlink:type="simple"/></disp-formula><p>which ends up in</p><disp-formula id="scirp.82712-formula181"><label>(41)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x368.png"  xlink:type="simple"/></disp-formula><p>This equation is the particle accelerated by a Lorentz force with only the electric field. We can qualify it as the macroscopic view of the system. One can</p><p>then define a force<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x369.png" xlink:type="simple"/></inline-formula>. Making the same assumption as in [<xref ref-type="bibr" rid="scirp.82712-ref3">3</xref>] , one can apply the four divergence to the normalized force</p><p><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x370.png" xlink:type="simple"/></inline-formula>:</p><disp-formula id="scirp.82712-formula182"><label>(42)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x371.png"  xlink:type="simple"/></disp-formula><p>with<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x372.png" xlink:type="simple"/></inline-formula>, the first term of the stress energy tensor (or<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x372.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x373.png" xlink:type="simple"/></inline-formula>), which is the EM energy density. Let us make the assumption that the particle is accelerated to the speed of light<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x372.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x373.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x374.png" xlink:type="simple"/></inline-formula>, and if the fluctuation of the total energy is equal to the fluctuation of the EM energy density (<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x372.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x373.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x374.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x375.png" xlink:type="simple"/></inline-formula>), thus we have also<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x372.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x373.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x374.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x375.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x376.png" xlink:type="simple"/></inline-formula>. The above equation is then:</p><disp-formula id="scirp.82712-formula183"><label>(43)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x377.png"  xlink:type="simple"/></disp-formula><p>or</p><disp-formula id="scirp.82712-formula184"><label>(44)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x378.png"  xlink:type="simple"/></disp-formula><p>Let us define the potential<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x379.png" xlink:type="simple"/></inline-formula>, and rewrite the previous equation</p><disp-formula id="scirp.82712-formula185"><label>(45)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x380.png"  xlink:type="simple"/></disp-formula><p>The infinitesimally variation <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x381.png" xlink:type="simple"/></inline-formula> is only due to the variation in time in the LHS term, then</p><disp-formula id="scirp.82712-formula186"><label>(46)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x382.png"  xlink:type="simple"/></disp-formula><p>with<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x383.png" xlink:type="simple"/></inline-formula>,</p><disp-formula id="scirp.82712-formula187"><label>(47)</label><graphic position="anchor" xlink:href="//html.scirp.org/file/13-7503406x384.png"  xlink:type="simple"/></disp-formula><p>Note that it is possible to consider higher order derivatives in time if we consider the variations of the quantity <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x385.png" xlink:type="simple"/></inline-formula> at higher orders (i.e. <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x385.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x386.png" xlink:type="simple"/></inline-formula>). However, one must also consider higher order variations of <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x385.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x386.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x387.png" xlink:type="simple"/></inline-formula> and q in order to agree with equation (45).</p><p>Also, it is worth to underline that equation (42) is established when considering only an electrical potential in the Lagrangian formalism of a point mass particle moving in an electrical field (i.e. Equation (34)). According to [<xref ref-type="bibr" rid="scirp.82712-ref21">21</xref>] , one can also include a magnetic potential within the Lagrangian, adding the</p><p>vector potential<inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x388.png" xlink:type="simple"/></inline-formula>. <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x388.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x389.png" xlink:type="simple"/></inline-formula>is the scalar product and <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x388.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x389.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x390.png" xlink:type="simple"/></inline-formula> is the magnetic potential. It follows that the term <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x388.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x389.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x390.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x391.png" xlink:type="simple"/></inline-formula> is added on the RHS of Equation (41) and the term <inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x388.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x389.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x390.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x391.png" xlink:type="simple"/></inline-formula><inline-formula><inline-graphic xlink:href="//html.scirp.org/file/13-7503406x392.png" xlink:type="simple"/></inline-formula> in the LHS of Equation (42). It forces to</p><p>do the same assumption as with the electric field in order to get an equation similar to equation (47). That is why, for the sake of the example, the addition of the magnetic potential is not so important.</p></sec></body><back><ref-list><title>References</title><ref id="scirp.82712-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Montillet, J.P. (2017) Bulletin of Mathematical Analysis and Applications, 9, 134-150. http://bmathaa.org/repository/docs/BMAA9-1-13.pdf</mixed-citation></ref><ref id="scirp.82712-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">Montillet, J.P. (2017) Journal of Modern Physics, 8, 1700-1722. https://doi.org/10.4236/jmp.2017.810100</mixed-citation></ref><ref id="scirp.82712-ref3"><label>3</label><mixed-citation publication-type="other" xlink:type="simple">Woodward, J.F. (2001) Foundations of Physics, 31, 819-835. https://doi.org/10.1023/A:1017500513005</mixed-citation></ref><ref id="scirp.82712-ref4"><label>4</label><mixed-citation publication-type="other" xlink:type="simple">Paul, T. (2007) Mathematical Structures in Computer Science, 17, 277-288.</mixed-citation></ref><ref id="scirp.82712-ref5"><label>5</label><mixed-citation publication-type="other" xlink:type="simple">Fernandez, F.M. (2000) Introduction to Perturbation Theory in Quantum Mechanics. CRC Press, Boca Raton. https://doi.org/10.1201/9781420039641</mixed-citation></ref><ref id="scirp.82712-ref6"><label>6</label><mixed-citation publication-type="other" xlink:type="simple">Montillet, J.P. (2013) Acta Applicandae Mathematicae, 129, 61-80.</mixed-citation></ref><ref id="scirp.82712-ref7"><label>7</label><mixed-citation publication-type="other" xlink:type="simple">Montillet, J.P. (2015) Acta Applicandae Mathematicae, 140, 43-70. https://doi.org/10.1007/s10440-014-9978-9</mixed-citation></ref><ref id="scirp.82712-ref8"><label>8</label><mixed-citation publication-type="other" xlink:type="simple">Hunter, J.K. (2009) Lecture Notes, Chap. 5. https://www.math.ucdavis.edu/~hunter/m218a_09/ch5A.pdf</mixed-citation></ref><ref id="scirp.82712-ref9"><label>9</label><mixed-citation publication-type="other" xlink:type="simple">Adams, R. and Fournier, J. (2003) Sobolev Spaces. Elsevier Academic Press, Cambridge.</mixed-citation></ref><ref id="scirp.82712-ref10"><label>10</label><mixed-citation publication-type="other" xlink:type="simple">Wilson, A.H. (1929) Proceedings of the Royal Society of London A, 122, 589-598. https://doi.org/10.1098/rspa.1929.0044</mixed-citation></ref><ref id="scirp.82712-ref11"><label>11</label><mixed-citation publication-type="other" xlink:type="simple">Dyson, F.J. (1929) Physical Review, 85, 631-632.</mixed-citation></ref><ref id="scirp.82712-ref12"><label>12</label><mixed-citation publication-type="other" xlink:type="simple">Costin, O. and Dunne, G.V. (2017) Journal of Physics A: Mathematical and Theoretical, 51, 04LT01.</mixed-citation></ref><ref id="scirp.82712-ref13"><label>13</label><mixed-citation publication-type="other" xlink:type="simple">Feynman, R.P. and Albert, R.H. (1965) Quantum Mechanics and Path Integrals. McGraw-Hill Companies, Inc., New York.</mixed-citation></ref><ref id="scirp.82712-ref14"><label>14</label><mixed-citation publication-type="other" xlink:type="simple">Frasca, M. (2009) Journal of Mathematical Physics, 50, Article ID: 102904.</mixed-citation></ref><ref id="scirp.82712-ref15"><label>15</label><mixed-citation publication-type="other" xlink:type="simple">Petit, R. (1993) Ondes Electromagnetiques en Radioélectricité et en Optique, Masson.</mixed-citation></ref><ref id="scirp.82712-ref16"><label>16</label><mixed-citation publication-type="other" xlink:type="simple">Feynman, R. (1964) The Feynman Lectures on Physics. http://www.feynmanlectures.caltech.edu/</mixed-citation></ref><ref id="scirp.82712-ref17"><label>17</label><mixed-citation publication-type="other" xlink:type="simple">Delmas, J.P. (1991) éléments de théorie du signal: Signaux déterministes, Ellipses.</mixed-citation></ref><ref id="scirp.82712-ref18"><label>18</label><mixed-citation publication-type="other" xlink:type="simple">Fearn, H. (2015) Journal of Modern Physics, 6, 260-272.</mixed-citation></ref><ref id="scirp.82712-ref19"><label>19</label><mixed-citation publication-type="other" xlink:type="simple">Tajmar, M. (2016) Revolutionary Propulsion Research at TU Dresden, Exotic Propulsion Workshop. Space Studies Institute, Estes Park. http://ayuba.fr/mach_effect/estes_park/ssi_estes_park_proceedings_tajmar.pdf</mixed-citation></ref><ref id="scirp.82712-ref20"><label>20</label><mixed-citation publication-type="book" xlink:type="simple">Woodward, J.F. (2004) Life Imitating Art: Flux Capacitors, Mach Effects, and Our Future in Space-Time. In: El-Genk, M.S., Ed., AIP Conference Proceedings: Space Technology Applications International Forum, Melville, New York, 1127-1137. https://doi.org/10.1063/1.1649682</mixed-citation></ref><ref id="scirp.82712-ref21"><label>21</label><mixed-citation publication-type="other" xlink:type="simple">Hornberger, B. (2009) Electric and Magnetic Forces in Lagrangian and Hamiltonian Formalism.http://insti.physics.sunysb.edu/itp/lectures/01-Fall/PHY505/09c/notes09c.pdf</mixed-citation></ref></ref-list></back></article>