4.1. Differential Equations of Motion
The oscillating electron of an atomic clock transitions back and forth between discrete electron shells, but it moves continuously on its way from one shell to the other, and as it is moving it is being accelerated by the gravitational field. Due to the extremely short distance the electron travels, the tiny duration of its path, and infinitesimal changes produced by the gravitational potential; the curvature of space-time may be neglected. Therefore within the infinitesimally small space-time region of the atom the equivalence principle is not just an approximation it is exactly true and the motion of the electron is subject to the laws of special relativity.
We are now prepared to answer the question posed in the introduction: How is it possible for the electron in an atomic clock to transition within the atom in a regular way while processing inputs from two physically distinct external sources, velocity and gravitational potential? The electron is subject to constraints imposed in two distinct space-times. Its discrete properties are determined by the four-dimensional volume λτ between electron shells; but another infinitesimal part, due to the equivalence principle, is transmitted continuously by gravitational field acceleration. To derive
local equations of motion for the electron that include both we use Minkowski space and invoke the concept of invariant spacetime intervals [
9]. “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.” Neither space nor time is assigned independent reality within the atom, rather a union of the two is preserved in the form of a spacetime interval.
The rate of an atomic clock does not speed up or slow down due to changes in the distance between electron shells. The distance between electron shells and the locally determined number of ticks per second of an atomic clock are invariant properties of matter because atomic structure is an invariant. Thus the electron in an atomic clock is subject to the invariant requirements of atomic structure due to the discrete nature of electron shells, yet at the same time it moves continuously in space-time during transitions between electron shells. For a complete determination of the equations of motion of the electron both discrete and continuous coordinates will be necessary.
From equations 1), 2), and 3) and the experimentally confirmed linearity of light we conclude that the electron of the atomic clock T
S oscillates at frequency
νCs with relativistic correction to
each cycle due to angular velocity relative to the center of the earth and correction to
each cycle due to an acceleration of coordinates
between ticks of the clock. An electron in free space accelerates under the influence of a gravitational field due to its mass by undergoing a change in velocity; however, an atomic electron cannot accelerate in the same way as a free electron because
the spacing between electron shells is an invariant. To describe the influence of gravitational fields on the electron of an atom we use Minkowski space, hold the spatial coordinates constant, and let time vary. The use of Minkowski space has the advantage that the spacetime distance of an electron transition is invariant, so that all local frames of reference will agree on the total distance in spacetime between the ticks of a clock. The invariant properties of Minkowski space make it indispensable to a description of atomic structure. It allows the microscopic equations of motion of a transitioning electron to be assigned a differential equation for the variation of time with respect to space,
where τ(x) is the invariant clock period of the atom in cycles per second,
represents a continuously applied correction due to kinematical time dilation, and
represents a continuously applied speeding up of time due to increases in gravitational potential. In ordinary space-time the motion of a particle is described by its change in position with respect to time. However, the motion of an electron in Minkowski space is given by
changes in spacetime interval. Therefore perturbation experiments with atomic clocks in a gravitational field suggest that time is not determined absolutely as in Newtonian mechanics, rather its most fundamental expression is to be found in the relativistic function of clocks as determined by the equivalence principle, where the time between clock ticks is determined by the spacetime interval of an electron transition.
4.3. Energy Absorption in a Non-Conservative System [10]
Due to the conservation of energy, absorption must occur before emission is possible. Quantization by a continuous absorption of energy is not amenable to a description by a purely field model because the fields are not bounded. Instead we use a particle model and describe the electron during continuous excitation between the states |1> and |2>. The Lagrangian for the electron is equal to the kinetic energy T minus the potential energy V, or L=T-V. The transition of an electron from the ground state to an excited state is characterized in generalized coordinates with six dimensions, three to describe its position on the electron shells R
1 and R
2, and three to describe its trajectory.
The electron initiates its motion at a point on the equipotential surface R
1 of the ground state at time t
1, is excited along a path r, and upon arriving at R
2 after a period of time, (t
2 – t
1) = τ, it assumes the experimentally determined orbital angular momentum, (T-V) = 2πE. In contrast to the Bohr semiclassical model of the atom this derivation of energy absorption assigns the correct value of zero for the ground state orbital angular momentum. The action, S[r(t)], is a functional that describes the absorption process in four dimensions. It has as its argument an infinite number of functions, the possible electron trajectories r(t). It differs from 5) by introducing physically defined end-points for the path as determined by the electron shells. The energy states |1> and |2> determine the energy and corresponding period of a field cycle. When we evaluate the action integral for a quantum mechanical change of state we obtain the familiar Bohr relation describing a photon
which is equivalent to the more familiar time-averaged relation E=hν. By treating time symmetrically with the space coordinates in four dimensions a relativistic theory describing energy absorption is obtained that accurately describes the behavior of a quantum oscillator. Electron transitions evolve continuously between the observed discrete ticks of a clock. Thus atomic structure requires two four-dimensional space-times, one discrete and one continuous, to allow implementation of the equivalence principle upon a transitioning electron and permit unification of the electromagnetic and gravitational fields in the simplest possible way, by ordinary coordinate superposition.
4.4. Energy Emission
In the previous section we described in 6) the non-conservative process of energy absorption from the environment and electron excitation. In this section we will describe its natural continuation, electron decay and the emission of a photon. The properties of energy absorption and emission for a bounded electromagnetic system, the atom, are of particular interest in our discussion for we wish to compare them with the time evolution of the absorption and emission of energy in a bounded gravitational system, the galaxy. It is not possible to make a direct comparison of gravitational and electromagnetic systems. Not only are the fields of vastly different strengths, but gravitational potentials do not share differences in polarity that are characteristic of electric charge. Despite glaring differences in their gross outward physical appearance, there are similarities that exist on a geometrical level. The kinetic flow of mass whether linear or rotational creates a transversely directed gravitational field that is analogous to the transverse magnetic field caused by current flow. The induced gravitomagnetic field, or force, is directed perpendicular to the mass flow and has been used to explain properties of relativistic jets emanating from the cores of quasars and other active galactic nuclei [
11]. It is postulated that due to mass-energy equivalence transversely directed forces occur in response to mass and energy flows of all types and that they may be compared to electromagnetic flows.
In order to compare the gravitational and electromagnetic energy flows we require an interpretation of quantum mechanics that treats energy not as an observable at single points in time as in non-relativistic theory, but as a continuous time evolution [
12]. Dirac described the problem simply and elegantly. “There is an alternative formulation for classical dynamics, provided by the Lagrangian. This requires one to work in terms of coordinates and velocities instead of coordinates and momenta. The two formulations are, of course closely related, but there are reasons for believing that the Lagrangian one is the more fundamental. In the first place the Lagrangian method allows one to collect together all the equations and express them as the stationary property of a certain action function. (This action function is just the time-integral of the Lagrangian.) There is no corresponding action principle in terms of the coordinates and momenta of the Hamiltonian theory. Secondly the Lagrangian method can easily be expressed relativistically, on account of the action function being a relativistic invariant; while the Hamiltonian method is essentially non-relativistic in form, since it marks out a particular time variable as the canonical conjugate of the Hamiltonian function. For these reasons it would seem desirable to take up the question of what corresponds in the quantum theory to the Lagrangian method of the classical theory.”
In Dirac’s first study, “The Lagrangian and the Action Principle”, he theorizes, “We ought to consider the classical Lagrangian not as a function of the coordinates and velocities but rather as a function of the coordinates at time t and the coordinates at time t+dt”. Rather than pick out a particular point in time as occurs with the Hamiltonian function of nonrelativistic theory, Dirac is seeking compatibility with relativity theory by calculating change in action over a space-time interval between two points in time. The results of the study proved to be accurate for they gave Feynman the idea to pursue a path integral formulation of quantum mechanics.
In the next section Dirac develops an idea complementary to the particle model with “An Application to Field Dynamics” that we wish to expand upon. He begins, “We may treat the problem of a vibrating medium in the classical theory by Lagrangian methods which form a natural generalization of those for particles. We choose as our coordinates suitable field quantities or potentials.” To obtain an equation that describes the energy emission by an atomic oscillator using field dynamics we introduce a Lagrangian density given by the fields and its first derivatives L(ϕi ,ϕi ,μ). This allows for a complete accounting of the energy interactions that occur during an electron transition, where ϕi is the current density described radially and ϕi,μ is the electromagnetic field strength described transversely. The transformation from a classical to a quantum viewpoint is realized by localizing the fields over the “region of space-time” between electron shells. Continuing with Dirac’s analysis, “We introduce at each point of space-time a Lagrangian density, which must be a function of the coordinates and their first derivatives with respect to x,y,z, and t, corresponding to the Lagrangian in particle theory being a function of coordinates and velocities. The integral of the Lagrangian density over any (four-dimensional) region of space-time must then be stationary for all small variations of the coordinates inside the region, provided the coordinates on the boundary remain invariant.”
Dirac’s field interpretation is a natural continuation of our description of absorption energy 6) and the next step in the time evolution of radiation processes. Emission initiates from the excited state R
2 = (x
2,y
2,z
2) at time t
2 and it finalizes at the ground state R
1 = (x
1,y
1,z
1) at time t
1. Each of the electron shells R
2 and R
1 determines a locus of points where the fields vanish and therefore they represent invariant field boundaries. We continue with Dirac’s arguments by requiring the integral of the Lagrangian density over the region of space-time between the excited and ground states to be “stationary for all small variations of the coordinates inside the region.” Changes in action are evaluated by integrating the Lagrangian density four-dimensionally thereby yielding a relativistic formulation of emission that is invariant, the same for all observers.
The end points of the electron’s path are located on equipotentials, space-like surfaces, and the four-dimensional localization of the fields necessarily corresponds to the result from 7), and the reduced Planck’s constant ћ. The action S[ϕi(t)] is a functional, a function of the values of coordinates on the discrete boundaries of the space-time surfaces R2 and R1 which are in turn functions of the continuous space-time variables of the fields within the surface. The boundaries of the fields are uniquely fixed four-dimensionally by the volume ∫d3x and the time interval t2-t1. The field model given by 8) describes one cycle of fields, or photon emission, as opposed to the particle model 6) which describes the excitation of an electron and one cycle of the fields. Two electron transitions, excitation and decay, equal one clock cycle and two field cycles.
Comparing 6) and 8) we see that emission and absorption are not symmetric processes since it is impossible to obtain the field distribution leading to absorption from that which resulted due to emission. Absorbed fields are unbounded whereas the emissions are bounded in space and time by the wavelength and period. Combined they represent a fully relativistic model that explains the quantization of energy as a four-dimensional localization of field in space-time, the photon. The electron shells define spatial boundaries in a way that is similar to the way the event horizon defines spatial boundaries for a black hole.
4.5. Comparison with Non-Relativistic Quantum Mechanics
The principal difference between relativistic and non-relativistic models of the quantization process is in their underlying physical assumptions. To formulate a relativistic theory we use a Lagrangian (T-V) and localize the fields £(ϕi, ϕi,μ) four-dimensionally, while in non-relativistic theory quantization is usually described with a Hamiltonian (T+V) as the potential of a point electron. To demonstrate their equivalence we will show how the two methods relate physically. In non-relativistic theory a particular type of wave function or “two-component spinor”, is used to describe energy emission. It defies explanation in ordinary space-time for it acts like an ordinary vector for infinitesimal rotations, but transforms to its negative for complete rotations and requires two complete rotations to return to its original state. Attempts to visualize spinor behavior make use of imaginary geometries such as the Möbius strip. Normally rotations and transformations of vector components and the coordinates describing them are carried out continuously. The same cannot be said for spinors. Spinors require two complete rotations to return to the original state, but they are constructed in such a way that they are sensitive to how the gradual rotation of coordinates was carried out to arrive there. In other words, they exhibit path dependence. More specifically, for any final configuration of the coordinates there are two topologically inequivalent continuous rotations of the coordinate system that result in this same configuration. It is impossible to carry out transformations between the two inequivalent rotations of coordinates even though they arrive at the same configuration. Because the spinor follows two independent paths it represents a non-conservative force.
A simpler explanation is possible by using physical arguments from the relativistic model. Rather than treat quantum mechanical energy emission as a single event carried out in two steps by a single particle, or 2-spinor, we use equations 6) and 8) to describe it with two field sources, an electron of field ϕi and a photon of field ϕi,μ , during two distinct physical processes, absorption and emission. The field ϕi of an electron has spin described by Pauli matrices oriented in three-dimensional space and the field ϕi,μ of a photon is oriented due to polarization in four-dimensional space-time by Maxwell’s equations. We interpret the 2-spinor therefore as the juxtaposition of two field geometries that cycle through the physical processes of excitation, localization, and emission. There are two paths possible, spin-up or spin-down, and two rotations are needed to complete a photon emission, where rotations are defined physically as changes in phase of the photon’s electromagnetic field during excitation and decay. Thus non-relativistic 2-spinors are rotations in abstract space and absolute time, which we interpret relativistically as the time evolution of real particle field geometries in Minkowski space.