Category Archives: Quantum mechanics

Photons are not particles

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In 1900, the German physicist Max Planck was studying black-body radiation, and he suggested that the experimental observations, specifically at shorter wavelengths, would be explained if the energy stored within a molecule was a “discrete quantity composed of an integral number of finite equal parts”, which he called “energy elements”. In 1905, Albert Einstein published a paper in which he proposed that many light-related phenomena—including black-body radiation and the photoelectric effect—would be better explained by modelling electromagnetic waves as consisting of spatially localized, discrete wave-packets. He called such a wave-packet a light quantum.
— https://en.wikipedia.org/wiki/Photon (20Jun24)

Photon energy is the energy carried by a single photon. The amount of energy is directly proportional to the photon’s electromagnetic frequency and thus, equivalently, is inversely proportional to the wavelength. The higher the photon’s frequency, the higher its energy. Equivalently, the longer the photon’s wavelength, the lower its energy… The photon energy at 1 Hz is equal to 6.62607015×10−34 J
— https://en.wikipedia.org/wiki/Photon_energy (20Jun24)

The SI units are defined in such a way that, when the Planck constant is expressed in SI units, it has the exact value h = 6.62607015×10−34 J⋅Hz−1.
— https://en.wikipedia.org/wiki/Planck_constant (20Jun24)

The meaning of the foregoing should be clear. Despite the claims of particle physicists that the photon is a particle, it was in its original conception and is in its current quantitative description a wave phenomenon. A photon is not a particle like a proton or a billiard ball. A photon is never at rest with respect to any material body; it is always moving at the local speed of light with respect to all material bodies. A photon does not behave like a three dimensional particle, it is a wave quantum.

A wave quantum is the smallest possible wave; it is a wave of one wavelength as defined above. The illustration below is of a wave consisting of two consecutive photons. This is a poor representation of the reality of electromagnetic radiation which on astronomical and cosmological scales is emitted omni-directionally by stars, galaxies and other luminous bodies. To a local observer though light arriving from a distance seems to consist of streams or rays of light. This image is of a subsection of such a stream.

Electromagnetic radiation does not consist of a stream of tiny particles simply because Max Planck was forced to treat the emission of light as having a discrete minimum. What is described by the math is a single wavelength which is the minimum for a wave of any frequency. Half waves and quarter waves etc. don’t exist.

That does not mean a wave with half the wavelength of a longer wave cannot exist, just that for any given frequency a single complete wave cycle of one wavelength defines the minimum wave energy. Converting this wave minimum to a “particle” was a categorical error and it has a formal name, QED or Quantum Electrodynamics.

In Richard Feynman’s 1985 book QED, based on four popular lectures he had given a few years earlier, he makes this rather odd case for the light as particle “theory:

The strange phenomenon of partial reflection by two surfaces can be explained for intense light by a theory of waves, but the wave theory cannot explain how the detector makes equally loud clicks as the light gets dimmer. Quantum electrodynamics “resolves” this wave-particle duality by saying that light is made of particles (as Newton originally thought) but the price of this great advancement of science is a retreat by physics to the position of being able to calculate only the probability that a photon will hit a detector, without offering a good model of how it actually happens.

So to summarize that last sentence, saying light is made of particles was a great advancement for science that represented a retreat by physics into incoherence. I can’t argue with that. It is also not clear why the particle theory is superior to the wave quantum understanding of Einstein. Surely wave mechanics could have been modified to accommodate the fact that one wavelength is the minimum wave.

Instead Feynman goes on to describe a strange system resembling vector addition where the direction of “arrows” representing possible particle paths is determined by a frequency counter clock, in a backdoor maneuver to introduce wave-like behavior into the particle model so it can mimic wave interference patterns. This fits nicely with the standard quantum babble about a superposition of states, the condition where a particle’s position cannot be predicted except as a probability distribution which is interpreted to mean that the particle is in many positions at once. Thus the retreat into incoherence.

The particle theory of light is just another screwup of 20th century theoretical physics (there were quite a few). It should be put on the historical-curiosity shelf along with the Big Bang next to geocentric cosmology. Future historians can point to these physically absurd dead-end theories as textbook examples of how not to do science. Theory driven physics always winds up as empirically baseless metaphysical nonsense; the human imagination has never been a good guide to physical reality.

Bohmian Mechanics & A Mathematicism Rant

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26JUN22 Posted as a comment to this Quanta article. Probably won’t be published there until tomorrow.

Contextuality says that properties of particles, such as their position or polarization, exist only within the context of a measurement.

This is just the usual Copenhagen mush, that substitutes a feckless by-product of the pseudo-philosophy of mathematicism for scientific rigor. The rather irrational, anthropocentric view that a particle doesn’t have a position until it is measured is entirely dependent on the belief that the Schrodinger wavefunction is a complete and sufficient description of physical reality at the quantum scale. It is not.

The Schrodinger equation only provides a statistical distribution of the possible outcomes of a measurement without specifying the underlying physical processes that cause the observed outcomes. The only scientifically reasonable conclusion would seem to be that the equation constitutes an incomplete description of physical reality. The Copenhagen interpretation of QM – that the wavefunction is all that can be known is not a rational scientific viewpoint. In physical reality things exist whether humans observe them or not, or have models of them or not.

There has long been a known alternative to the wavefunction only version of QM that was championed by John Bell himself. In Bohmian mechanics, in addition to the wavefunction, there is a particle and and a guiding wave. In that context the wavefunction provides the outcome probabilities for the particle/guiding-wave interactions. Bohmian mechanics constitutes a sound scientific hypothesis; the Copenhagen interpretation (however defined) offers nothing but incoherent metaphysical posturing. As in:

The physicists showed that, although making a measurement on one ion does not physically affect the other, it changes the context and hence the outcome of the second ion’s measurement.

So what is that supposed to mean exactly, in physical terms? The measurement of one ion doesn’t affect the second ion but it does alter the outcome of the second ion’s measurement? But what is being measured if not the state of the second ion? The measurement of the second ion has changed but the ion itself is unaltered, because the “context” changed? What does that mean in terms of physics? Did the measurement apparatus change but not the second particle? It’s all incoherent and illogical, which is consistent with the Copenhagen interpretation I suppose, but that’s not saying much.

Bohmian mechanics makes short work of this matter. There are two charged particles, each with a guiding wave; those guiding waves interact in typical wave-like fashion in the 4 dimensional frame of electromagnetic radiation. The charged particles are connected in, by, and across that 4D frame. By common understanding, such a 4D frame has no time dimension. That is what accounts for the seemingly instantaneous behavior. That’s physics, it could be wrong, but it is physics. Contextuality is math; math is not physics.

Theoretical physics in its current guise is an unscientific mess because physical reality has been subordinated to mathematical and metaphysical considerations. And so we have the ongoing crises in physics in which the standard models are so discordant with physical reality in so many different ways that it seems difficult to say what precisely is wrong.

The simple answer is that you can’t do science that way. Attempting to build physics models outward from the mathematical and metaphysical realms of the human imagination is wrong. Basing those models on 100 year old assumptions and holding those outdated assumptions functionally inviolable is wrong.

Science has to be rooted in observation (direct detection) and measurement. Mathematics is an essential modeling tool of science but it is only a tool; it is not, of itself, science.

Theoretical physics, over the course of the 20th century, devolved into the study of ever more elaborate mathematical models, invoking ever more elaborate metaphysical conjectures of an invisible realm knowable only through the distorted lenses of those standard models.

Physical reality has to determine the structure of our theoretical models. Currently theorists with elaborate models dictate to scientists (those who observe, measure, and experiment) that they must search for the theoretical components of their models, or at least some signs and portents thereof. Failure to find the required entities and events does not constitute a failure of the model however, only a failure, thus far, of detection (dark matter, etc.) or the impossibility of detection (quarks, etc.). In any event the models cannot be falsified; they need only be modified.

Modern theoretical physics is an exercise in mathematicism and it has come to a dead end. That is the crisis in physics and it will continue until the math first approach is abandoned. It is anybody’s guess when that will happen. The last dark age of western science persisted for a millennium.