Why does everyone believe in particles?

[Lorentz Jr]

Why are all the theories of quantum mechanics formulated in terms of particles? I don't see any conclusive evidence for their existence. They seem like an artifact of classical thinking. Tiny little "objects" that no one can see.

Even quantum field theory is based on a similar idea, that fields are inherently quantized, that quanta are "entities" of some kind, which requires "probability waves", with not even an attempt to explain more deeply what they might be based on.

Max Planck started the quantum revolution with his theory of black-body radiation, and the whole physics community took that to mean that electromagnetic waves are quantized. But black-body radiation isn't just electromagnetic waves, it's the generation of electromagnetic waves. An interaction between the electron field (or whatever the system is made of) and the electromagnetic field. Why can't that be the source of quantization? Choosing the target field as the reason for quantization seems arbitrary when the quantization is always associated with an interaction.

If matter and energy are continuous fields with quantized interactions, there's no need for mysteries like the "wave-particle duality", and maybe there would be a way to eliminate the infinities in the calculations of quantum field theory. Fields would still be effectively quantized, sort of, but only indirectly, through their interactions.

The only complication I can think of is that I'm not sure how direct interactions could be quantized, since each interaction would have to involve two quantization coefficients. So there would probably have to be something like a form of energy that mediates interactions. Not a field, exactly. Something localized. What we call "particle detections" would be localized interactions with the field(s) of detectors, and what we call "virtual particles" would be failed interactions, where the energy goes back to the field it came from.

A particle traveling through space would be an ordinary wave packet in its field. A particle making a track through a bubble chamber would be a wave packet that keeps getting localized repeatedly through interactions with the fluid.

Is there any evidence for particles independent of their interactions? Any data that requires fields to be quantized when they're not being measured?

Edited November 29, 2022 by Lorentz Jr

[swansont]

26 minutes ago, Lorentz Jr said:

Tiny little "objects" that no one can see.

But can be detected. Quanta that are consistent with observation.

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Is there any evidence for particles independent of their interactions?

Is there any evidence other than all the evidence?

How else are you going to detect something other than some interaction?

[Sensei]

39 minutes ago, Lorentz Jr said:

Why are all the theories of quantum mechanics formulated in terms of particles? I don't see any conclusive evidence for their existence. They seem like an artifact of classical thinking. Tiny little "objects" that no one can see.

 

The naked eye can see the traces left by particles with high kinetic energy, that is, one particle collides with the medium (nuclei + electrons), losing its kinetic energy and accelerating the medium particles, ionizing them, electrons and sometimes nuclei are repelled.

 

49 minutes ago, Lorentz Jr said:

Is there any evidence for particles independent of their interactions?

Paraphrasing you: Is there any evidence for anything independent of their interactions?

[Lorentz Jr]

1 hour ago, swansont said:

Is there any evidence other than all the evidence?

"All" of the evidence, except for phenomena that are characterized by uncertain locations and are described by wave functions.

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How else are you going to detect something other than some interaction?

Two sharp concentrations of detections on the far screen, along lines from the source to the two slits between the source and the screen. That would be evidence of particles existing between interactions, but it's not what actually happens.

45 minutes ago, Sensei said:

The naked eye can see the traces left by particles with high kinetic energy,

Right, but that's only on a macroscopic scale. It doesn't rule out wave packets that stay localized because they keep interacting with the fluid.

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Is there any evidence for anything independent of their interactions?

Diffraction and other wave phenomena obviously suggest the existence of waves, and I'm suggesting that interactions themselves can be explained without the idea of particles. So I don't understand why the particle model of matter is so historically tenacious.

Edited November 29, 2022 by Lorentz Jr

[joigus]

1 hour ago, Sensei said:

 

The naked eye can see the traces left by particles with high kinetic energy, that is, one particle collides with the medium (nuclei + electrons), losing its kinetic energy and accelerating the medium particles, ionizing them, electrons and sometimes nuclei are repelled.

 

Paraphrasing you: Is there any evidence for anything independent of their interactions?

+1. Beautifully illustrated. You can even tell that some of these particles have orbital angular momentum in the direction perpendicular to their motion.

There's plenty of evidence that we're dealing with particles.

There's plenty of evidence that their behaviour is accounted for by a wave.

The only thing that's left to do is to deal with it.

[swansont]

1 hour ago, Lorentz Jr said:

"All" of the evidence, except for phenomena that are characterized by uncertain locations and are described by wave functions.

Which are not evidence of particles, so what is your point?

1 hour ago, Lorentz Jr said:

Two sharp concentrations of detections on the far screen, along lines from the source to the two slits between the source and the screen. That would be evidence of particles existing between interactions, but it's not what actually happens.

Ah, I see we’ve moved the goalposts. You asked about evidence of particles, but now it’s “particles existing between interactions”

 

 

1 hour ago, Lorentz Jr said:

Diffraction and other wave phenomena obviously suggest the existence of waves, and I'm suggesting that interactions themselves can be explained without the idea of particles. So I don't understand why the particle model of matter is so historically tenacious.

Evidence of wave behavior is evidence of wave behavior. Evidence of particle behavior is evidence of particle behavior 

[MigL]

That's the thing about quantum particles, we can't determine much about them before detection/interaction; they are simply a mathematical expression of probability distributions.
And, upon detection, their properties ( wave-like or particle-like ) depend mostly on the detection mechanism.

As a result, we have various models which must be applied to differing circumstances.

[studiot]

2 hours ago, Lorentz Jr said:

Why are all the theories of quantum mechanics formulated in terms of particles? I don't see any conclusive evidence for their existence. They seem like an artifact of classical thinking. Tiny little "objects" that no one can see.

Please clarify the scope of this discussion.

What do you mean by particles ?

And is the discussion to be limited to particles as related to quantum mechanics ?

 

The idea and knowledge of both waves and particles goes back several thousand years.

Obviously these ideas have been extended and refined greatly over that period.

In that time we have discovered phenomena that are best explained in terms of particles and also phenomena that are best explained in terms of waves and some phenomena that could be explained in terms of either.
At first some aspect of each particular phenomenon allowed a distinction to be made. For instance the direction of deflection in refraction.

But late in the 19th century phonema were discovered that fitted neither model (you haven't forgotten that both waves and particles are just models have you ?) completely and contradicted each model in some (different) way.

QM was originally introduced as a way of reconciling phenomena that fitted this category.

As many more such phenomena were discovered in the burgeoning scientific world qm grew in importance and value and developed to what it is today.

A better model that describes more phenomena.

But it is still only a model.

[Sensei]

1 hour ago, Lorentz Jr said:

Diffraction and other wave phenomena obviously suggest the existence of waves, and I'm suggesting that interactions themselves can be explained without the idea of particles.

There are double-slit experiment for electrons and other particles. Scientists can fire one particle at a time, with a delay, and detect single hits on the screen, which after a while, seconds, minutes or hours, will form a diffraction pattern. This depends on the kinetic energy/momentum of the particle used in the experiment.

https://en.wikipedia.org/wiki/Davisson–Germer_experiment

 

[Lorentz Jr]

1 hour ago, swansont said:

Ah, I see we’ve moved the goalposts. You asked about evidence of particles, but now it’s “particles existing between interactions”

No, the goalposts were always there. Because I'm a realist and I don't like the idea of things magically transmogrifying into other things.

30 minutes ago, studiot said:

And is the discussion to be limited to particles as related to quantum mechanics ?

Yes. I'm not interested in any other context.

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What do you mean by particles ?

I mean the notion that quantization is an intrinsic property of matter and energy. Planck invented the concept of quantization in connection with a type of interaction that produces radiation, and I would like to know why theorists seem to exclusively associate the quantization with the radiation itself rather than (possibly) the interaction that produced it.

Edited November 29, 2022 by Lorentz Jr

[studiot]

15 minutes ago, Lorentz Jr said:

 

Yes. I'm not interested in any other context.

I mean the notion that quantization is an intrinsic property of matter and energy. Planck invented the concept of quantization in connection with a type of interaction that produces radiation, and I would like to know why theorists seem to exclusively associate the quantization with the radiation itself rather than (possibly) the interaction that produced it.

The short answer is "They don't"

Actually that is not what Planck postulated, nor did he introduce the term quantum or quanta, that was Einstein a few years later.

Rather than arguing back and for about it, here is the official Cambridge University history.

[TheVat]

Thread seems to draw from the long debate between scientific realism and anti-realism (going back to Carnap and the logical empiricists and then onto other antirealist views, Feyerabend et al).  The common form being instrumentalism (SUAC).  

(Clip from SEP, with my boldings) In the historical development of realism, arguably the most important strains of antirealism have been varieties of empiricism which, given their emphasis on experience as a source and subject matter of knowledge, are naturally set against the idea of knowledge of unobservables. It is possible to be an empiricist more broadly speaking in a way that is consistent with realism—for example, one might endorse the idea that knowledge of the world stems from empirical investigation and contend that on this basis, one can justifiably infer certain things about unobservables. In the first half of the twentieth century, however, empiricism came predominantly in the form of varieties of “instrumentalism”: the view that theories are merely instruments for predicting observable phenomena or systematizing observation reports. (End clip)

Some empiricists of the more antirealist persuasion would insist that the word "particle" can only mean, say, "white streak in a cloud chamber" and have no ontological force as to whether particle-like interactions actually involve discrete particulate entities.  

LIke @Lorentz Jr I am leery of reifying interactions as 

4 hours ago, Lorentz Jr said:

Tiny little "objects" that no one can see.

The particle paradigm is so powerful because of its utility, and because it is so hard to visualize anything else, like say field perturbations or knots of field strength or wave packets or what have you.  

It's also worth asking: can we speak of a truly "elementary" entity as having properties within itself?  The macro scale concept of an object is one that implies a thing that could be split, subdivided, crushed, etc. a concept which has no validity in the realm of elementary particles.  At that level, we seem to be in a realm where things only take on meaning interacting with something else - in the macro scale, this would be like a table that is only a table when you set a fruit bowl, or lunch, on its upper surface.  Elementary particles are bundles of interactive properties - but no substance.  They are particles in a specific and peculiar way that bears little relation to the word's usual usage where we speak of "particles of..." 

[Lorentz Jr]

2 hours ago, Lorentz Jr said:

I would like to know why theorists seem to exclusively associate the quantization [of black-body radiation] with the radiation itself rather than (possibly) the interaction that produced it.

1 hour ago, studiot said:

here is the official Cambridge University history.

Quote

This idea ... amounted to dividing energy into discrete packets (quanta) ...
Einstein ... showed that Planck's quanta had the required property of concentrating their energy at points ...
Quanta had to be accepted.

Yes, this is exactly what I'm talking about.

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The short answer is "They don't"

?????

Quantization has to be accepted. But quantization of what? Quanta I'm not so sure about.

Edited November 29, 2022 by Lorentz Jr

[studiot]

20 minutes ago, Lorentz Jr said:

Yes, this is exactly what I'm talking about.

Thank you, but you also said a deal of other stuff, which is confusing as to your intentions.

1) I see neither a field nor a particle nor an interaction involved in black body radiation.

2) Not all fields are 'quantized.

3) Einstein's contribution was most definitely about the interaction, although as it takes two to tango, you can't simply concentrate on one or the other.

 

[Lorentz Jr]

2 hours ago, TheVat said:

can we speak of a truly "elementary" entity as having properties within itself?

And can we speak of any entity as being truly "elementary"? 😵

It's a strange, strange world.

Anyway, I'm impressed by a lot of what I've read by Lee Smolin, and he's convinced that there's a serious misconception buried deep in the heart of quantum mechanics. Physicists love to make a big deal out of giving up cherished misconceptions when they disagree with experiments, but it seems to me that their noble ideals may hide a darker fact, that they're clinging to a misconception that they cherish even more than traditional scientific principles -- namely, the classical ontology of matter as "solid objects" and the vacuum as a "substanceless void" that those objects travel through. So, from a scientific point of view, they've thrown out the baby and kept the dirty bathwater. Maybe that's why they're having so much trouble unifying quantum mechanics with gravity.

1 hour ago, studiot said:

I see neither a field nor a particle nor an interaction involved in black body radiation.

I see thermal energy in the object, and then I see that energy being emitted by the object in the form of radiation. So, I'm not sure how you think that can happen without some kind of interaction.

Edited November 29, 2022 by Lorentz Jr

[exchemist]

6 hours ago, Lorentz Jr said:

Why are all the theories of quantum mechanics formulated in terms of particles? I don't see any conclusive evidence for their existence. They seem like an artifact of classical thinking. Tiny little "objects" that no one can see.

Even quantum field theory is based on a similar idea, that fields are inherently quantized, that quanta are "entities" of some kind, which requires "probability waves", with not even an attempt to explain more deeply what they might be based on.

Max Planck started the quantum revolution with his theory of black-body radiation, and the whole physics community took that to mean that electromagnetic waves are quantized. But black-body radiation isn't just electromagnetic waves, it's the generation of electromagnetic waves. An interaction between the electron field (or whatever the system is made of) and the electromagnetic field. Why can't that be the source of quantization? Choosing the target field as the reason for quantization seems arbitrary when the quantization is always associated with an interaction.

If matter and energy are continuous fields with quantized interactions, there's no need for mysteries like the "wave-particle duality", and maybe there would be a way to eliminate the infinities in the calculations of quantum field theory. Fields would still be effectively quantized, sort of, but only indirectly, through their interactions.

The only complication I can think of is that I'm not sure how direct interactions could be quantized, since each interaction would have to involve two quantization coefficients. So there would probably have to be something like a form of energy that mediates interactions. Not a field, exactly. Something localized. What we call "particle detections" would be localized interactions with the field(s) of detectors, and what we call "virtual particles" would be failed interactions, where the energy goes back to the field it came from.

A particle traveling through space would be an ordinary wave packet in its field. A particle making a track through a bubble chamber would be a wave packet that keeps getting localized repeatedly through interactions with the fluid.

Is there any evidence for particles independent of their interactions? Any data that requires fields to be quantized when they're not being measured?

I must say it has always seemed to me that the notion of "particles" is a fairly preposterous construct, when one thinks about it: the idea of an entity with no physical dimensions but nevertheless finite properties such as mass, charge, intrinsic angular momentum etc. Just as artificial as "waves", really. Originally, in classical physics, the concept of particles was merely used to simply physics problems to their essentials, for ease of modelling. 

Like you, it has often seemed to me that QM entities only behave like particles when they interact. Reading Rovelli's Helgoland last year, I was quite impressed by his idea that QM entities only have defined properties at all when they interact, so we should perhaps let go our idea that they possess them in a continuous sense in between. 

  

Edited November 29, 2022 by exchemist

[Lorentz Jr]

4 minutes ago, exchemist said:

QM entities only have defined properties at all when they interact, so we should perhaps let go our idea that they possess them in a continuous sense in between.

Or maybe let go the idea that they're entities. They could be mere phenomena.

[Sensei]

2 hours ago, Lorentz Jr said:

But quantization of what?

If you have a physical quantity, like charge Q, in Coulombs, and start dividing it, billions of billions of times, you can reach a certain threshold where it does not allow further division, i.e. Q/e = total number of electrons.

[swansont]

38 minutes ago, Lorentz Jr said:

Or maybe let go the idea that they're entities. They could be mere phenomena.

Particle phenomena? Wave phenomena?

[Lorentz Jr]

55 minutes ago, swansont said:

Particle phenomena? Wave phenomena?

Particles are entities.

[studiot]

2 hours ago, Lorentz Jr said:

I see thermal energy in the object, and then I see that energy being emitted by the object in the form of radiation. So, I'm not sure how you think that can happen without some kind of interaction.

Since I didn't see it before and I don't see it now, please enlighten me.

 

Interaction of (what)  with (what)  ?

[swansont]

1 hour ago, Lorentz Jr said:

Particles are entities.

So they can’t be phenomena?

And we shouldn’t let go of the idea that they are entities?

Can you please give a consistent position?

[Lorentz Jr]

2 hours ago, studiot said:

Interaction of (what)  with (what)  ?

Interaction of whatever electrons are (or whatever the system is made of, or whatever its thermal energy is made of) with whatever radiation is made of. I don't understand what part of that is so complicated. I'm assuming it doesn't just happen by magic. (a) Thermal energy disappears from the system and radiation appears in the space around it, (b) I assume there must be some kind of process that makes that happen, and (c) I'm suggesting that maybe the process itself is quantized.

1 hour ago, swansont said:

So they can’t be phenomena?

And we shouldn’t let go of the idea that they are entities?

Can you please give a consistent position?

Particles are entities by definition, and I'm suggesting that maybe matter isn't made of particles or entities of any kind at all. In other words, I'm saying that maybe there is no "they". Maybe matter is just ordinary, unquantized waves, and the particle side of the wave-particle duality is an illusion created by quantized interactions between waves in ordinary, unquantized fields. Is that consistent enough?

Maybe we should take a break. I know this is the Speculations area, but I really don't want things to get too hostile. 😶

Edited November 29, 2022 by Lorentz Jr

[swansont]

39 minutes ago, Lorentz Jr said:

Particles are entities by definition, and I'm suggesting that maybe matter isn't made of particles or entities of any kind at all. In other words, I'm saying that maybe there is no "they". Maybe matter is just ordinary, unquantized waves, and the particle side of the wave-particle duality is an illusion created by quantized interactions between waves in ordinary, unquantized fields. 

Why don’t atoms absorb part of the energy of an EM wave? e.g. a 2 eV emission hitting an atom that allows a 1 eV excitation.

[Lorentz Jr]

1 hour ago, swansont said:

Why don’t atoms absorb part of the energy of an EM wave? e.g. a 2 eV emission hitting an atom that allows a 1 eV excitation.

I'm assuming you mean the energy of N photons, where hf < 1eV and Nhf = 2eV?

I was saying earlier, there would have to be a localized form of energy that mediates interactions, so fields wouldn't interact with each other directly. hf would have to be the quantization of interactions between the EM field and the intermediary.

Please don't be mad at me. I know this all probably sounds hokey and ignorant, but I'm really not trolling. I just don't like a lot of things in modern physics, and I'm trying to make sense of them as well as I can.