Apparent wave/particle duality of photons.

Energy propagates at a fixed velocity through a vacuum, designated as C. Experiments with light indicate the apparent duality of a photon’s state – light will act in a wave-like or a particle-like manner depending upon the conditions of the experiment. In one such experiment, photons take all possible routes to their destination (wave-like) unless forced to take only a single path (particle-like) by the configuration of the testing apparatus, a situation which poses certain difficulties in assessment as the photons’ paths are determined before the state has been forced.


Relativistic temporal distortion indicates that as an observer’s velocity approaches C, the rate of subjective time passing for that individual slows relative to that of the objective universe at rest. Extrapolating this to a photon, massless and travelling at C (with an “undefined” value relative time calculated as a value of time divided by the square root of zero), it would follow that a photon experiences no subjective temporal period of existence between its emission and its absorption. This offers a simple explanation for light’s seeming ability to choose the proper state before it is forced into the state, provides an insight into the passage of time for the universe as a whole, and suggests a reason for the fixed propagative velocity of all energy.

When electromagnetic energy such as light is emitted from a source, it propagates in a vacuum at a fixed rate represented by the constant C. It continues at this velocity until absorbed regardless of the relative velocity of the observer, which indicates a fixed propagative rate measured against a universal common scale. Light also possesses an unusual quality in that it will behave at times like a particle and at others as a wave due to constraints “later” along its path of propagation.


Figure 1: Twin-slit optical experiment layout for testing wave-like properties.

In one experiment (See Figure 1), photons are emitted and split along two paths by a special type of crystal. These photon streams are deflected by mirrors to return and pass through a pair of slits and then absorbed by a detector or illuminating a viewable surface. The photon streams create a pattern of light and dark referred to as an interference pattern. This pattern indicates the energy has traveled along all possible routes from emitter to detector in a wave-like manner.


Figure 2: Twin-slit optical experiment layout for testing particle-like properties.

A similar experiment (See Figure 2) is identical to the first, save that a polarizing filter has been placed in the path of one photon-stream, allowing only photons of the correct orientation to pass along that route and to the detector. The photon streams in this case create a twin pattern of light scattering, indicating that each photon’s energy has traveled along only one route from emitter to detector as would a stream of particles.

What makes a comparison of these experiments interesting is that the path a photon takes is determined at a point prior to that at which it experiences the presence or absence of the polarizing filter affecting its behavior. Thus, it has already taken the ‘correct’ path before it has encountered the conditions that will determine that path.

This becomes an issue if light is considered to experience a subjective temporal sequence of events in concert with our own. If light is considered to have no such temporal event sequence, then from its emission until its absorption would be considered a single timeless event. Thus, the ‘later’ presence of the filter would affect the ‘earlier’ behavior of the photon’s energy by virtue of the fact that the path of the photon’s energy is fixed so that it will pass along all possible paths as they will be during its entire existence. If only one path will later be possible, then that is the only path the photon’s energy distribution will follow. If more than a single path is possible, then all paths will share the distribution of the photon’s energy.

Position A B C D E
t(observer) 0 1 3 5 6
t(photon) 0 0 0 0  0

Figure 3:Temporal progress for an observer and photon between emission (A) & absorption (E).

A comparison of relative temporal progress (See Figure 3) illustrates the differential between a photon’s subjective temporal event sequence and that of an external observer at rest. This viewpoint offers a number of interesting possibilities, while simultaneously explaining the seeming particle-/wave-like duality. Simply put: a photon’s energy will always be distributed along all possible paths as they will exist during the period of time between emission and absorption. If only one path is available, it will follow only that one path and so reveal particle-like behavior. If more than one path remains available, the energy will follow all paths in a wave-like manner.

In a future post, I will discuss the implications of a fixed rate of observational velocity regardless of the energy imparted to a single photon.

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