Argues that wave-particle duality is a weakness in the foundations of physics. Suggests abandoning inadequate analogies, accumulating evidence from experiments into a holistic framework and using open-minded deductive logic to search for credible and comprehensive unified model. As an example it makes a start on assembling the evidence from classic optical experiments. The approach suggests a candidate prototype model and this is used illustrate the overall approach. The prototype model (dubbed phots) is examined for its potential to explain a range of reflection, polarisation, refraction, diffraction and interference experiments, culminating in Young’s double slit experiment. Although created for heuristic purposes, the phot model seems to show some promise. The overall project raises a range of interesting questions, ideas and ideas for experiments.

Introduction

Light is an amazing entity. It is our window to the Universe and Nature. Some examples are over a billion times bigger than others. It has perplexed humanity since the ancient Greeks. Over the last four hundred years it has attracted the attention of hundreds of great scientists.

A particle model for light prevailed in the 17th and 18th century but was overtaken by a wave model in the 19th century. At the start of the 20th century, Planck, Einstein and others explained new experiments with light in terms of quantised photons. The great physicists of the day tried to reconcile the resurgent particle model with the prevailing wave model but failed. So they reluctantly parked the issue by creating an approach called wave-particle duality.

Using two contradictory models for a fundamental feature of the Universe is obviously unsatisfactory. Putting up with this is an admission of defeat. A century has gone by since the wave-particle compromise and there have been significant advances in quantum mechanics, relativity, atomic physics, optics and cosmological physics. This may assist the development of a better model.

The essays preceding this one have suggested an approach to developing a credible, consistent, comprehensive model for light. The approach recommends putting misleading analogies aside, starting with an open mind and focusing on the evidence from experiments. Accumulate all the key evidence and avoid jumping to conclusions to early. Develop conjectures but do not let these blinker creative thinking. Then test the conjectures against the key evidence. Let the evidence speak. Eventually a better model for light will begin to reveal itself. With any luck it will be simple and intuitively appealing. But it might not be. But if it can explain all the available evidence it will suggest new experiments and new insights. So it is worth a try.

As an example of this approach a project was begun. Light was codenamed ‘phots’ to reduce the mental baggage from inappropriate analogies. Evidence was gathered from a range of key experiments and used to inspire ideas and also to constrain them. Although just an example of the approach the prototype model that began to emerge was rather interesting. It may even have some merit. It is too early to tell. A lot more evidence and some rigorous mathematical analysis need to be brought into the framework.

If a unified model does emerge from a fresh open minded and logically rigorous examination of the evidence from relevant experiments it would obviously upset the current unsatisfactory paradigm. Challenging paradigms is never easy, as Galileo Galilei would agree. There would be many objections to the new ideas, some of them valid but capable of resolution. For some the discord with established beliefs and mental patterns would be uncomfortable. On top of that would be an enormous drag from “paradigm inertia”. Hundreds of text books and teaching notes and on-line videos would need to be improved. Relativity took decades to become established. A new understanding of light would probably take longer.

Here is a sample and summary of some of the main points in the preceding essays.

Wave Model

It has to be recognised that the wave model mathematics are clever and successfully describe the outcomes of hundreds of experiments involving interference effects. However, this does not mean that every aspect of the wave model is literally correct. It might be the case that the wave model gets the right answers for the wrong reasons. There are many aspects of the wave model that can be questioned. Here are some of them:

The Huygens wavelet principle cannot be literally true. Where are the generators of the secondary wavelets? They are often imagined where there is no material at all, especially if the experiment takes place in a vacuum. Why do the wavelets propagate only forward? And how can they have the same wavelength as the source wave? They should each carry a tiny amount of the energy in the incident wave. Energy in a light wave is proportional to its frequency (E = Planck’s constant x frequency) so small amounts of energy correspond to small frequencies. But the wavelength is the speed of light c divided by the frequency, so each wavelet then has a very large wavelength. Which sort of spoils the whole story.
If light consists of spreading wave fronts then the energy in each part of the wave would rapidly diminish with distance from source.
What is going on in regards to polarisation? The wave model tells a convincing story about waves being made up of P and S waves and uses this to explain effects like Brewster’s angle. But no mention is made of this in the explanation of interference effects.
Understandably the classical wave model does not take into account the insights provided by Special Relativity. If something is travelling at the speed of light in the observer’s inertial reference frame, Special Relativity teaches that it has no length in the direction of travel, and that time within the moving system is at a standstill. This is hard to reconcile with the picture of light as made up of wriggling electro-magnetic worms.
The wave model cannot explain a range of experimental observations such as Compton scattering and the photo-electric effect.

However, the wave model has the merit that its mathematical expression works very well over a wide range of optical phenomena.

Particle Model

The particle model is obviously incomplete because it cannot describe many of the classic experiments that the wave model describes quite well. The mental image of little bullets of energy being fired out by the source has very limited usefulness.

Modern quantum electrodynamics works much better because mathematical models, if they are sophisticated enough, can be made to model anything. And yet there seems to be something incomplete and strange about quantum mechanics. For example physicists have come to believe quantum events involving light in one part of the Universe can instantly affects quantum events involving light in another part of the Universe, no matter what the separation. For a counter to this belief see (Van de Vusse, 2024).

Naive attempts to merge the Wave and Particle Models

Having to use two incompatible models for a fundamental aspect of the Universe is intuitively unsatisfactory and many attempts have been made to reconcile the wave and particle approaches. One approach models light as long wriggly lines of electro-magnetic disturbance and then attempts to quantise this by chopping the lines into short pieces. This makes no sense at all. The wriggling drawings are supposed to be timelines, not three dimensional objects. And in any case the storyline is at odds with Special Relativity.

Another attempted reconciliation is to say that light travels like a wave but interacts like a particle. The simple version of this imagines the classic wriggly wave concept. The fancy version turns light into a quantum probability wave. A twist on this conceptualisation is to put it the other way around. Light arrives at an two slit experiment or a Mach-Zender interferometer say, and then it somehow becomes a wave, or possible two waves, or possibly many waves until it is time to become a particle again and go into a photo-multiplier tube. Oddly enough, this view may have some merit.

The wave and particles model both have strengths and weaknesses. Which is why they complement each other and also contradict each other.

The phot protocol is to abandon unsatisfactory analogies and use a bottom up evidenced based framework for assembling the evidence from experiments until a logical holistic model starts to reveal itself.

The picture that is emerging is not a wave, nor is it a particle. Nor is it one or the other in turn, or something in between. It is what it is. It does however have some elements of both waves and particles. It is essentially a discrete package of energy, so in that sense it is like a particle. It also has an effective width, and this can be thought of as a section of wave front.

Generally the phot approach tries to steer away from trying to imagine what a phot looks like in flight and to focus more on what a phot does when it interacts. We cannot ‘see’ a phot in flight. We can only ever see the effects of its destruction, and then only on property at a time. For people brought up on Star Wars and Space Trek you could say that phots can only be studied in detail when they drop out of hyperspace.

Basic Phot Properties – Evidence from Key Experiments

Phots are created when charges particles are decelerated with respect to the rest of the Universe and/or an excited electron drops down to a lower energy level. Most commonly in stars, but also by warm bodies of matter, radioactive decay and man made devices including radio transmitters, microwaves, lamps, heaters, X-rays and gamma rays generators.
Phots are essentially discrete packets/bundles of energy travelling at the maximum speed possible.
What we can observe is a variety of effects that arise when a phot interacts with something else. But only one property for any one phot, because to observe a phot is to destroy it. There are many effects but we can only observe one property for any particular phot. What we see/observe/detect is an effect of the phot’s destruction.
If we use an array of phots generated in similar circumstances and the ones sampled demonstrate a particular effect if is fair to infer that the other phots would show the same effect if they were sampled.
If a phot demonstrates a particular effect when it is destroyed, we need to be careful about assuming it has that property ‘in flight’. We cannot observe a phot in flight. We can deduce its path from things it doesn’t hit, or by observing/destroying other phots in the same ray.
We need to be very careful about our mental model of what a phot is ‘in flight’. We can only observe the effects of phot destruction. (If we came across a plane crash we not would conclude that the plane was made from twisted burnt metal. But we could infer that metal was involved in its construction.)
By taking the insights of Special Relativity to their limit we can infer that a phot has no length in the direction of its motion. It may not have length but it does have an effective sideways presence that we can call its ‘effective width.’
Also by taking the insights of Special Relativity to their limit we can infer that a time aboard a phot is essential at a standstill. A phot does nothing much except travel. Whether or not it rotates in fight is an open question. Rotation here would mean that the direction of the inherent electric disturbance capacity changes as the phot travels with distance. This can be explored experimentally by sampling some of the phots in a beam of identical phots.
The main property of a phot is its energy. A kind of whip crack of pure electro-magnetic energy. It also has an orientation, phase and spin.
An incident phot creates a mix of electro-magnetic disturbances that can be modeled as two sinusoidal waves of electric field intensity, orthogonal to each other and with a phase delay between them.
The resultant combined wavy effects have magnitude and direction (orthogonal to the path) at any particular instant. Both usually fluctuate. The direction at a particular instant is called the orientation.
The resultant wave has a frequency. The frequency is proportional to the phot’s energy
Phots can arrive at any point in the cycle of these effects. This is called their (overall) phase.
The two sinusoidal waves of electric field intensity have a phase delay between them, up to 90 degrees ahead or behind. At zero degrees the resultant effects lie in a plane. The orientation stays constant. This is called linear polarisation. At ninety degrees difference the result is that the electromagnetic effects always start with the same maximum, but with an orientation that apparently rotates as the phot travels, either clockwise or anti-clockwise. This is called circular polarisation. Smaller phase differences between the two sine wave drivers produce elliptical polarisation when the phot interacts.
Studying rays of phots indicates that polarisation properties can be inferred for phots in flight.
The observation/destruction of phots also reveals a strange property call spin. It is a small fixed amount of angular momentum, always the same size and always either in the direction of travel or opposite direction to travel. Spin is inferred to be a property of phots is flight. But it is not thought to indicate that the phot is actually spinning.
Phots can deliver more than this amount of angular momentum. The extra is called orbital angular momentum. Imagining how a phot encodes angular momentum effects is not yet clear. (The phot protocol tries to avoid jumping to premature conclusions. The emphasis is on gathering evidence, a bit like a jigsaw puzzle. The picture will emerge by itself and a process of logical reasoning.)
When a phot interacts, its energy, phase, orientation and angle of incidence influence what happens next. But the atoms, electrons and fields in the target zone are also fluctuating and uncertain, so the outcome for a particular phot is probabilistic.
The three main options are reflection, refraction or absorption. But if the target zone is very thin, or has a hole or slit in it, the outcomes are more complicated.
Reflection can be considered to be absorption of a parent phot and emission of a child phot. The child phot can have some properties different from its parent.
Phots travel slower in optically dense surroundings. Higher energy phots slow down the most. This explains why their path bends (refracts) more than the path of lower energy phots (Snell’s Law).
There are other properties as well. It would take a book or two to describe all the evidence. Two of the most important are:

In the vacuum of free space, phots always travel at speed c. You cannot make a phot go faster or slower by emitting it from a moving source. All that happens is that you change its energy level. You can also get more or less energy by moving the detector towards or away from the source.
Phots are affected by gravity. They travel more slowly in the presence of gravity. Their path can be bent by gravity. If they are created in a region of strong gravity and detected in a region of less strong gravity they are observed to have lost some energy.

Here are some extra comments for some of the above properties of phots suggested by the basic evidence:

Effective width: Phots have a presence in a plane orthogonal around their path of travel and centered on their line of travel. This presence decreases with distance from the line of travel. It is not yet clear whether this presence is uniform in space or constant in time. But it is useful for a simple description of Snell’s Law and some key experiments involving refraction, diffraction and interference. Including the “evanescent wave’ that turns up during total internal refections, and why higher energy phots are at the top of Newton’s spectrum. The concept of effective width is not related to quantum mechanics theories about a physical size of photonic particles.

Child Phots: The conventional models seem to assume that waves and particles ‘bounce off’ reflective surfaces and ‘pass through’ polarising filters. The phot model interprets the evidence as suggesting that phots are absorbed and instantly reborn as child phots. The energy stays the same but other properties can change, notably phase and orientation. This is useful for understanding many experiments, notably the three polarisers experiment. It also suggests that optical Bell experiments claiming to have demonstrated supra-luminal action at a distance need to check whether incorporating mirrors into their apparatus have violated the conditions for Bell’s Theorem to apply.

Comment

We are taught and have come to accept that wave-particle duality is a fundamental mystery of the Universe. But not everything we are taught is true. Just because the great minds of physics at the time could not come up with a self-consistent comprehensive unitary model does not mean that it is fundamentally impossible. Yes there are some difficult experiments and phenomena to explain, but persistence and fresh thinking might eventually prevail.

What is certain is that the task is bigger than any one person. It would take a collaborative effort from many talented people to develop a unified model, express it in elegant mathematics, test it and put it to use.

Doubtless there would be obstacles and missteps along the way, and many doubters and detractors. The topic is not an esoteric backwater. It is a cornerstone of physics and fundamental to our perceptions and understanding of our Universe and all its physics.

Reference

Van de Vusse, Sjoerd B.A., 2024, Some ideas and experiments for issues affecting modern physics, https://hereticalphysics.com.au
Author contact: SBAvan@utas.edu.au Author’s location: Hobart, Australia

Towards a Unified Model for Light – Progress Summary