[jeffreyH]

I though I had a good idea about quantum mechanics until I started studying it more in depth and understanding its strangeness. The photon cannot be described physically. Only modelled.

[Colin2B]

The photon cannot be described physically. Only modelled.

I'm pretty sure the same is true of the wave side as well, too easy to think like water or sound waves.

[yor_on]

True, we evolved to search for symmetries and patterns Collin. I think of that as both a strength and a limitation. The thing we see as a logic is also a pattern called causality.

[hamdani yusuf (OP)]

I though I had a good idea about quantum mechanics until I started studying it more in depth and understanding its strangeness. The photon cannot be described physically. Only modelled.

I think many strangeness in quantum mechanics are related to result of double slit experiment, when the light is interpreted as photon particle.
I’ve shown in my experiments about diffraction of light that double slit aperture is simply an obstacle with four edges. How the photon model explains the effect of removing the outer edges (which makes it a thin wire diffraction, which according to Babinet’s principle, should produce the same pattern as single slit aperture)?
How the photon model explains the result of circular pattern when the diffraction grating is vertically tilted?

[Bill S]

Hamdani, I applaud the work you seem to be putting into this, and really hope you reach a conclusion with which you are satisfied.

My very inexpert comment would be that you are dealing with quons (sensu Herbert), and therefore may find that, not only are our models all oversimplifications, but that this is especially the case when we start looking closely at QM. 
 
Maybe, one day it will be discovered that QM gives us a “window” to infinity.  Should this be the case, all we can hope for in our 3+1 dimensional “reality” is improved modelling.

[hamdani yusuf (OP)]

Many strangeness in results of experiments showing single photon detection that we found in popular science news hide complexities faced by experimenters. We can even find some papers published in scientific journal depicting a single photon going through complicated macroscopic device such as beam splitter and prism, and stays as single photon on detector.

Referring to photomultiplier tubes handbook from Hamamatsu Photonics, we find that single photon detection is not as simple as depicted in popular documentary movies. In my opinion, the existence of dark current and thermionic emission reduce credibility of single photon detection. Instead, they show electron detections from earlier stages of the dynode.

https://www.hamamatsu.com/resources/pdf/etd/PMT_handbook_v3aE.pdf

[Bill S]

Interesting looking link Hamdani.  I've read the intro, but there is no way I'll have time to wade through the lot. If you could point me in the direction of the part(s) that cover the difficulties of single photon detection, I'd be obliged.

[hamdani yusuf (OP)]

Interesting looking link Hamdani.  I've read the intro, but there is no way I'll have time to wade through the lot. If you could point me in the direction of the part(s) that cover the difficulties of single photon detection, I'd be obliged.

you can find link to a chapter about single photon detection mode, and see a graph representing output signal. You will find a statement about a threshold to differentiate which spike counts as photon reading, which counts as noise.

[Bill S]

Thanks, Hamdani, it's certainly something I intend following up when time permits; but there is so much going on on TNS at the moment that I have to prioritise, and that's not easy.

[hamdani yusuf (OP)]

Why Did We Invent a SOUND PARTICLE? Phonon and Quasiparticle Physics

We know that light behaves as a wave AND a particle... but can we treat sound in exactly the same way? And what about this exciting new particle known as the "dance particle"?

Hey everyone, in this video I wanted to discuss how physicists like to take complicated physics phenomena and model them as atoms in order to hugely simplify the mathematics used to solve problems. The main example I'll be discussing is the treatment of sound waves as particles known as phonons. Now technically, these particles are QUASIparticles because they're not real, and are just a mathematical reimagination of the sound wave. This is slightly different to light, because light particles (photons) DO actually exist. We have plenty of evidence to show us that the wave model of light is not enough to explain certain things we observe, such as the photoelectric effect, black body radiation (ultraviolet catastrophe) and so on. In fact, light needs both the wave model and the particle model to explain all the phenomena we observe. However a sound quasiparticle (phonon) is not like this - it's a mathematical trick.

The reason we work with quasiparticles at all, becomes very evident when we consider the reality of a sound wave moving through a solid, for example. The sound wave is formed by the oscillation of atoms in the solid. The bonds between atoms allow energy to be transferred from one region in the solid to another, and as soon as the disturbance has passed, the atoms return to their original positions. Now if we want to study how sound waves move through the solid in any detail, then we have to consider the position of each affected atom, as well as the strength of the bonds between atoms. We can treat these bonds like springs, though this is a big simplification. But even then we have to consider the "stiffness" of the springs, which is dependent on the type of atoms forming the bond. And then we may have to think about the disturbances to each atom at every instant in time, if there are multiple sound waves moving through the solid in different directions. Things become complicated very quickly. Instead, if we treat the atoms in the solid as a "background", and the sound wave as a sound particle, then we only need to consider the phonon representing each wave rather than the (likely) tens of thousands of atoms in the solid, and how their positions change over time.

Another example we will discuss is when electrons in a solid can escape from their energy levels, leaving behind a vacancy. This vacancy can be filled with nearby electrons, making it seem as if the vacancy is moving around within the solid. This is treated as its own quasiparticle, known as a "hole", and is much easier to deal with than considering all the electrons filling any nearby vacancy.

More information about the electron hole quasiparticle: https://en.wikipedia.org/wiki/Electro...​

Timestamps:
0:00​ - The DANCE particle + how physicists work with quasiparticles
0:38​ - How we deal with light - waves and particles (photons)
1:06​ - Sound waves: oscillations in air (+ other gases liquids and solids)
1:59​ - Sound wave in a solid: atomic structure and bonds transmit energy
3:53​ - Treating sound waves as particles (phonons) - quasiparticles
5:37​ - Why phonons are useful (multiple sound waves and phonon-phonon interactions)
6:15​ - Electron hole quasiparticles (vacancy vs electron motion)

What convinced us that photon is any more physical than phonon?

[alancalverd]

We know that light behaves as a wave AND a particle.

No. Light behaves as light. We model it as a wave or a particle.

[hamdani yusuf (OP)]

We know that light behaves as a wave AND a particle.

No. Light behaves as light. We model it as a wave or a particle.

The sentence was quoted from the description of the video.
In many cases light behaves similar to other kind of waves. In other cases it behaves similar to other kind of particles.
The question is, is it possible to explain wavelike behavior of light using particle model?
Is it possible to explain particle-like behavior of light using wave model?
What additional assumptions are required to achieve those tasks?

[alancalverd]

The question is, is it possible to explain wavelike behavior of light using particle model?
Is it possible to explain particle-like behavior of light using wave model?

No. The only connection is E = hν.

The photon-phonon parallel comes from Planck's original concept of electromagnetic "waves in a box" which leads to the quantification of black body radiation and the explanation of the black body spectrum. If you want to describe nuclear motion in a regular solid you can use the same fundamental concept and end up with quantised collaborative excitations which explain some properties of solids, particularly charge transport in semiconductors.

[hamdani yusuf (OP)]

No. Light behaves as light. We model it as a wave or a particle.

Is it still valid if the word light is replaced by sound?

[alancalverd]

No. Sound is compression waves in a medium. The particles of the medium certainly move but do so cyclically - there is no gross motion in the direction of propagation, and sound does not propagate in vacuo.

[hamdani yusuf (OP)]

No. Sound is compression waves in a medium. The particles of the medium certainly move but do so cyclically - there is no gross motion in the direction of propagation, and sound does not propagate in vacuo.

What do you think about AC electric power transmission through metal wires? Is it similar to sound, or light? Is it a completely different type of phenomena?

[hamdani yusuf (OP)]

I just found a video explaining this topic pretty convincingly. The best part IMO, is that he made the experiment in real life, not just a simulation.

[wolfekeeper]

Phonons are quantum mechanical phenomena, just like photons in fact.

Photons and how they interact with electrons are extremely well described in modern physics by quantum electrodynamics:

https://en.wikipedia.org/wiki/Quantum_electrodynamics

[Kryptid]

What convinced us that photon is any more physical than phonon?

Because, unlike phonons, photons don't rely on a medium to transmit them.

[hamdani yusuf (OP)]

Phonons are quantum mechanical phenomena, just like photons in fact.

Photons and how they interact with electrons are extremely well described in modern physics by quantum electrodynamics:

https://en.wikipedia.org/wiki/Quantum_electrodynamics

The video shows that imagining photons like extremely small particles produces more questions than answers. In many situations they behave like waves.