Correction June 28, 2022: The classical wave-equation should read d/dt d/dt partial W(x,t) = vv d/dx d/dx partial W(x,t) Historically two types of “free” mechanical motions were considered, that of Newtonian mechanics x=vt (v=constant) and classical waves such as waves on a string which were described in terms of Newton’s laws for a continuous medium. It seems these two were considered as fundamentally different phenomena. Equations of motion were developed for classical mechanics as well as electromagnetic phenomena. Maxwell discovered that electromagnetic equations allowed for a classical wavelike solution which he identified as light. In the early 1900s it was realized that to retain electromagnetic equations invariance as seen from a constant moving frame moving, Lorentz transformations were needed. In 1905 Einstein obtained these transformations in a different manner considering that light has the same vacuum speed when viewed from different constant moving frames. Later in the 1920s quantum mechanics was developed using the idea of a probability wave exp(-iEt+ipx) for a free particle beginning with the work of deBroglie who made use of ideas of special relativity. In this note we suggest that there seems to be one fundamental “free” mechanical motion, namely that associated with a wave exp(-iEt+ipx) whether one considers a classical wave or a quantum free particle. Classical mechanics is a mapping into a continuous x-t space, we argue, and describes energy and momentum motion in this continuous space. This same description also occurs for classical waves. The medium undergoes a somewhat complicated nonlocal change, but the “velocity” of the wave maps to a continuous local space time i.e. v=x/t=dx/dt where E= pv. E=pv, however, is only a description of energy momentum propagation given in a simple form. It does not describe the overall picture. We argue the same is true for the simple x=vt (v=constant). It seems that an overall wave structure is associated with energy and momentum and for free motion this is linked with exp(-iEt+ipx). If this wave is fundamental one may argue that its phase may remain constant when viewed from different frames moving at constant v. Special relativity would then follow from this requirement and so is in a sense a consequence of wave behaviour. We investigate these ideas.
Correction June 28, 2022: The classical wave-equation should read d/dt d/dt partial W(x,t) = vv d/dx d/dx partial W(x,t) Historically two types of “free” mechanical motions were considered, that of Newtonian mechanics x=vt (v=constant) and classical waves such as waves on a string which were described in terms of Newton’s laws for a continuous medium. It seems these two were considered as fundamentally different phenomena. Equations of motion were developed for classical mechanics as well as electromagnetic phenomena. Maxwell discovered that electromagnetic equations allowed for a classical wavelike solution which he identified as light. In the early 1900s it was realized that to retain electromagnetic equations invariance as seen from a constant moving frame moving, Lorentz transformations were needed. In 1905 Einstein obtained these transformations in a different manner considering that light has the same vacuum speed when viewed from different constant moving frames. Later in the 1920s quantum mechanics was developed using the idea of a probability wave exp(-iEt+ipx) for a free particle beginning with the work of deBroglie who made use of ideas of special relativity. In this note we suggest that there seems to be one fundamental “free” mechanical motion, namely that associated with a wave exp(-iEt+ipx) whether one considers a classical wave or a quantum free particle. Classical mechanics is a mapping into a continuous x-t space, we argue, and describes energy and momentum motion in this continuous space. This same description also occurs for classical waves. The medium undergoes a somewhat complicated nonlocal change, but the “velocity” of the wave maps to a continuous local space time i.e. v=x/t=dx/dt where E= pv. E=pv, however, is only a description of energy momentum propagation given in a simple form. It does not describe the overall picture. We argue the same is true for the simple x=vt (v=constant). It seems that an overall wave structure is associated with energy and momentum and for free motion this is linked with exp(-iEt+ipx). If this wave is fundamental one may argue that its phase may remain constant when viewed from different frames moving at constant v. Special relativity would then follow from this requirement and so is in a sense a consequence of wave behaviour. We investigate these ideas.
We take as our starting point the free particle classical action which may be written as A= -Et+px if t and x are treated as independent variables. It is possible to find two relationships linking v (velocity) to x and t from dA=0. The first is the classical wave result vp = E while the second is p=Ev where E=mo/sqrt(1-vv) (c=1). Furthermore one may write dA/dx partial = p ((1a)) and dA/dt partial = -E. ((1b)) This may be generalized to two eigenvalue differential equations, but this immediately begs the question: Why do this? We argue that Lorentz invariant form -Et+px represents scaling of both t and x. For example, p scales x and we argue there should be physical relevance to this. This physical relevance results in the wavelength proportional to 1/p. In other words, -Et+px represents more than velocity. The treatment of the scaling for a quantum wave and classical wave differ, we argue, in that the former keeps E,t and p,x separate while a classical wave does not. In other words pv=E applies to a classical wave which is described by cos(-Et+px). In other words, one takes ((1a)) and ((1b)) which separate E,t and p,x into two independent equations and takes account of scaling by combining the two (to include both x and t) i.e. creating the classical wave equation: 1/vv d/dt d/dt partial W(x,t) = d/dx d/dx partial W(x,t). We argue that quantum mechanics on the other hand keeps ((1a)) and ((1b)) separate. The velocity (relativistic) p=Ev is not a wave velocity. A solution to ((1a)) is exp(ipx) and to ((1b)) exp(-iEt). These are usually combined for a free particle to give exp(-iEt+ipx) and a wave is described with a phase velocity pv(phase)=E. We prefer to keep exp(-iEt) and exp(ipx) separate . For example, for two slit interference one does not make use of phase velocity or exp(-iEt). For a bound state one uses p=Ev, but a single free particle is represented by exp(ipx) in W(x)=wavefunction = Sum over p a(p)exp(ipx). exp(-iEn t) appears after one has found En, using the exp(ipx)’s in the sense that one does not include an exp(- i pp/2m t) for each exp(ipx). We argue that by separating E,t and p,x, the latter leads to a scheme for which there is “no time”. It is true that the particle moves at a speed x/t, but p=m1v1=m2v2 etc so p does not uniquely define velocity, rather it defines an impulse hit 2p = Integral F dt . Thus the scaling px which leads to an x, p only wave exp(ipx) is linked to an interaction. If the particle is moving freely and not interacting, then one has classical determinism i.e. v=constant = x/t. As soon as an interaction occurs, one changes from variables x,t which are linked to x, P conditional (x/p) and there is uncertainty in the position of x within a wavelength. The phase in exp(ipx) is only dependent on x not on the time the particle reaches x. exp(ipx) thus represents a probability and one must consider a sum of different possible outcomes (as in a two slit experiment) in order to describe an interaction. This is very different from the local interaction of classical mechanics. Nevertheless for a bound state one makes use of the two formalisms i.e. KE(x)= Sum over p pp/2m a(p)exp(ipx) / W(x) = KEclassical(x). We try to discuss some of these ideas in this note.
The classical action (relativistic or nonrelativistic) may be written with v=x/t and x and t varied independently to yield dA/dx partial = p and dA/dt partial = -E. Thus A = -Et+px is a solution. This expression also appears in classical wave forms and in the electromagnetic description of a photon (from Maxwell’s laws). -Et+px is a Lorentz invariant and so is directly linked to special relativity and different frames moving with constant velocity. In (1) we argued that x and t should be treated as independent in A. This suggests that p is a scaling in space and E in time. Thus there should be physical lengths proportional to 1/p and physical time intervals proportional to 1/E. Special relativity considers different frames (moving with constant velocity) and 4-vectors so it seems to be quite different from a scenario with t and x separated and scaling of x by p. We argue that although -Et+px is a Lorentz invariant and as such may be used to find E(v) and p(v), quantum mechanics is usually performed in a special frame, namey one in which V(x) or V(x,v) the potential is at rest. (For electromagnetism one treats (A, phi) as a 4-vector, but this is not the norm.) As a result, energy En found in a rest frame of the potential also represents “rest energy” so En is binding energy which is added to rest mass energy. In other words motion in the rest frame of a potential creates rest energy = rest mass. We argue that V(x) may be written as a sum over k Vk exp(ikx) and so no time related terms appear, only momentum linked ones. Thus momentum is the key feature for the interaction, even though velocity and time are still in the picture (just sometimes not directly in the interaction scheme). For example, a two slit interference or single slit diffraction does not depend on time or speed although these are certainly in the problem. For a bound state v and t are also in the problem as one calculates average kinetic energy using pp/2m = .5 p v which is rate dependent, but there is no acceleration which is a time-dependent phenomenon. Rather one deals with an ensemble of exp(ipx)’s because these interact with the potential in a wavelike manner to create the effect of acceleration. exp(ipx) a momentum wave linked to the scaling of x by p in px is not only involved in an interaction with V(x), but represents extra information from the classical mechanical picture. exp(ipx) for a known rest mass mo means one knows v=x/t=dx/dt, yet there is an extra piece of information namely the phase px which is involved in even “free” interactions such as two idendical particle with different phases arriving at the same x at the same t or the average kinetic energy in a bound state. Velocity v is converted into a momentum expression through p/mo in the norelativistic case and so exp(ipx) governs the whole scenario. Acceleration then becomes a mathematical abstraction of the motion of vrms(x) for any quantum bound energy level with the real physics associated with exp(ipx) being ignored.
Momentum and velocity are two well-known physical observables in classical physics (and quantum physics as well because quantum particles have impulse and move through space in a certain amount of time based on an external clock and ruler). They are, however, measured in different ways. Velocity describes motion through x in some time t, while p is measured through impulses. Thus one does not need a clock to measure momentum. It may be measured in terms of the damage done to a foil, compression of a spring etc. Thus p=m1v1=m2v2 etc., i.e. a numerical number associated with momentum does not automatically yield the velocity unless one knows rest mass. In many situations rest mass is known (i.e. one deals with an electron etc) and so there seems to be a tendency to consider momentum and velocity to be almost the same thing when they are distinctly different. In fact, we argue that the notion of wavefunction W(x) and density P(x)=W*(x)W(x) are associated with momentum and velocity respectively. In fact, for a free particle these two measurables are linked with completely different spatial probabilities. Constant velocity impies P(x)=constant while exp(ipx) describes the two-dimensional x-probability associated with p which is based on a constant mo and v. In special relativity for a free particle (i.e. p constant, v constant), there are two well known Lorentz invariants: EE = pp + momo (c=1) and A = -Et + px. One may note that v does not appear explicitly even though one may write E and p in terms of v i.e. E = mo/sqrt(1-vv) and p=Ev. The first invariant describes E in terms of rest mass and p (measured through impulse). The second involves p,E and x,t with x and t appearing as independent even though ultimately x(t) and v=dx/dt=constant = x/t if x and t both start at 0. This independence is crucial because it means one may consider fluctuations which keep A constant separately. For example, if t→ t+ hbar/E and x→ x+hbar/p, then A remains constant. This leads to the idea of the quantum wavelength and a spatial probability independent of t, namely exp(ipx). One average, however, x=vt, but how does this appear in Lorentz invariants? There is no explicit v. We argue that the Lorentz invariant A = -Et + px must convert E from a function of p to one in v and that this occurs through a Legendre transformation. Thus the form of the invariant is itself a Legendre transformation with E being transformed into L, the Lagrangian. There is, however, a second important feature because p=dL/dv (partial) and given that p is constant, dp/dt=0 so d/dt dL/dv partial =0 which is in the form of an extremization. We argue that this is not an accident. dL/dv=p follows from E being constant, so, in other words, it follows from the px term. This same term leads to exp(ipx) which means that one does not have smooth x=vt motion within a wavelength. Thus, we argue that when one transforms to the second measurable v, the notion of this fluctuation behaviour must also be manifested. In other words, v=constant or dv/dt is not enough. The extremization behaviour of the Lagrangian, we argue, is thus not a mathematical convenience, but gives an indication that even though the extreme path x=vt is followed on average, other paths are sampled. We argue that this idea is incorporated into special relativity, in fact within a single Lorentz invariant A = -Et + px.
We have argued in previous notes (1) that the “wave” nature of quantum mechanics follows from the Lorentz invariant for a constant p: A= -Et+px which holds for both a particle with rest mass and a photon. In A, t and x are separated indicating independence which violates the Newtonian view x(t). “A” leads to dA/dx partial = p and dA/dt= -E. Creating eigenvalue equations yields: -id/dx exp(ipx) = p exp(ipx) and id/dt exp(-iEt) = E exp(-iEt). Thus, x and t may be separated. Given that exp(ipx) exists in all of space (because there is no time), it represents a somewhat spatially invariant probability. In the case of a photon, Maxwell showed one may write wave equations for the electric El and magnetic B fields using his electromagnetic equations with no charge or currents.. He showed the wave travels at the speed of light in a vacuum and thus characterized light as an electromagnetic wave. This is not the same statement as exp(ipx) which is a probability wave. One may note that Maxwell’s equations are Lorentz invariant, so the ideas of the first paragraph should hold. In this note, however, we consider the Poynting equation: d/dt partial (.5( eoElEl+1/uoBB)) + 1/uo grad dot El x B = function(charge and current). 1/uo ElxB is considered to be a momentum density. We note Maxwell’s equations contain d/dt partial and d/dx partial, so time and space are considered independent (unlike x(t)), and act on El and B. The presence of charge and current densities breaks spatial invariance i.e. creates local regions. We argue in this note that d/dx and d/dt are generators of translations in space and time. We further argue that Maxwell’s theoretical creation of a photon follows from introducing spatial invariance into the problem, i.e. removing all charge and current densities. Spatial invariance in Newtonian mechanics, however, is associated with a constant i.e. a constant speed and momentum and equal probability to be at any x. Given that d/dx and d/dt appear, one has a function of space and time which seems to be completely at odds with spatial invariance and the idea of a constant momentum. We have argued in (2), however, that constant motion, even though represented by v=constant, is associated with the force that created the momentum, and this manifests itself in a spatial density which is probabilistic. Thus the presence of d/dt and d/dx in Maxwell’s electromagnetic equations, even when charge and current densities are removed, implies the same thing. Thus we argue that Maxwell’s electromagnetic equations are probabilistic. We investigate these ideas in this note. We further argue that it is spatial invariance, together with the presence of d/dx partial which yields the periodic form exp(ipx). Thus it is not a coincidence that wave equations appear for El and B.
In (1) a Galilean transformation x’ = x-vt and t’=t is applied to the Schrodinger equation id/dt (partial) W(x,t) = -1/2m d/dx d/dx W(x,t) for a free particle, where W(x,t) is the wavefunction, and it is argued that W’(x’,t’) does not equal W(x(x’t,t’),t(x’,t’)). Instead it is shown that W’(x’,t’) = W(x,t) exp( -i/bar [mvx’+.5mvvt’] with x=x’+vt’ and t=t’. The author’s of (1) suggest this is due to remnants of special relativity creeping into the nonrelativistic situation. They then argue that this issue is already found in nonrelativistic classical mechanics, in particular in the Hamiltonian-Jacobi equation H(x, dS/dx) + dS/dt = 0 where S is the free particle action= t *Lagrangian and H is the Hamiltonian i.e 1/2m dS/dx dS/dx. They show that S’(x’,t’) = S(x,t) - (mvx’ +.5mvvt’) and also argue that this is due to a remnant of special relativity creeping into nonrelativistic classical mechanics. In this note, we consider the free particle action S= -Et+px nonrelativistically. (This form also holds for the relativistic free particle). It may be seen that such a solution satisfies the Hamilton-Jacobi equation, but the catch seems to be that one must transform both (x,t) and (p,E) to find a solution in a moving frame. The Galilean transformation leads to two different transformations, one for (x,t) and another for (p,E). A Lorentz transformation on the other hand treats (x,t) and (p,E) in the same way and -Et+px behaves as a dot product with a (1,-1) type metric. We argue that given the physical example of a particle with rest mass mo at x=0 at t=to, a moving frame transforms this into a new energy (including mo and kinetic energy), a p and x’,t’ such that x’/t’=v where -v is the velocity of the frame. One may suggest a more general transformation than the Galilean i.e. replace t’=t with t’=g(v) t. This then leads to -Et+px written in terms of E’,t’, p’,x’ equalling -E’t’ + p’x’ if g(v) = 1/sqrt(1-vv/bb) where b is a constant to make v/b dimensionless. Applying the transformation, which we assume holds for both (x,t) and (p,E) to light yields b=c. One may then show that -Et+px, written in terms of E’,t’,p’,x’, yields -E’t’ + p’x’,
Note: The equations d/dx partial [ T L] = p and d/dt partial [ TL] = -E hold for both the relativistic and nonrelativistic free particles because dL/dv = p and H=pv-L hold for both the relativistic and nonrelativistic free particle. In part I of this note, we argued that in quantum bound states one has a notion of dx and dt associated with p and E i.e. dx→1/p and dt→1/E, but not of continuous time associated with particle motion. exp(-iE t) contains time t, but this refers to a cycling time associated with various exp(ip1x) free particle probabilities combining with exp(ikx) to form exp(ipx). In other words there is a certain time resolution as well as a space resolution (wavelength) for the single particle and time t refers to the entire quantum resonance. In a bound system, there is also a vrms(x) which holds for every quantum energy state En and this is linked to a continuous space time picture i.e. x(t). It is this x(t) which gives a sense of past, present and future. A quantum system, however, is a statistical system much like V(x) a potential. It does not follow a particle from one x to another in space because the potential renders stochastic hits. It is only interested in the overall resonance which forms. “t” in exp(-iEt) is associated with this resonance and not with single particle motion. Thus there is no classical sense of past, present or future in the quantum bound state at least with respect to the single particle. An entire quantum system may, however, evolve, but a bound system simply cycles through time. The single particle has no time attributes except dt associated with 1/E where E=pp/2m. In part 1 we argued that p may be thought of in terms of impulse (hits). In such a case it is not directly linked to space and time. We also argued that p=mo v even in the quantum case so dx and dt must be present indirectly. In this note we revisit these ideas by following (1) and deriving quantum mechanical behaviour for a free particle from the classical Lagarangian equations dL/dx (partial) = p and H= pv - L. This directly shows that a quantum picture deals with dx and dt for a single free particle and so the idea of x(t) only holds in an rms sense. For a single free particle, matters differ from the bound case because p = mo vrms (free particle). Thus we argue that exp(ipx) must be viewed in terms of probability and is only manifest if an interaction occurs.Such interactions, however, may be continuously occurring as in the case of the Bohm Aharonov effect in which there is a magnetic vector potential existing in a large region of space.