I Do Hidden Variables include sub-structures?

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TL;DR Summary

Bell's Theorem rules out any hidden variables but does it rule out some finer structure to quantum particles?

Summary: Bell's Theorem rules out any hidden variables but does it rule out some finer structure to quantum particles?

At larger scales of the universe, we would see entanglement as cloning. For example, two human clones have the same color eyes because their DNA is identical. I've been reading some on entanglement and wondered if Bell's theorem rules out a finer structure as a hidden variable?

 

[Nugatory]

Yes, any theory that says there is some finer structure that, if understood, would allow us to calculate the results of quantum mechanical observation is pretty much by definition a hidden variable theory.
If you are going to use the eye color analogy... Mendelian genetics itself is a hidden variable theory; the hidden variables are the chromosomes and DNA. The point of Bell’s theorem is that no future discoveries will explain quantum mechanics the way the discovery of chromosomes and DNA explain why eye colors come out the way they do.

Do note that Bell’s theorem does not rule out all hidden variable theories. It rules out a particular type of hidden variable theories, the ones that are casually described as “local realistic” and more precisely described by the assumptions that go into the proof of the theorem. These include pretty much anything that we’d accept as a non-weird explanation of quantum weirdness.

 

[Demystifier]

Summary: Bell's Theorem rules out any hidden variables but does it rule out some finer structure to quantum particles?

First, Bell's Theorem does not rule out any hidden variables. It only rules out local hidden variables. Second, it definitely does not rule out finer structure. For instance, Bell's theorem applied to a proton does not rule out the quark fine structure of the proton.

 

[Elias1960]

I like to object against the "local" hidden variables excluded. What has been excluded is appropriately named "Einstein-local" or "Einstein-causal".

How would you name a theory so that all objects have localization in space, there is also a maximal speed, but one much higher than c? This would be an obviously local theory. But in that naming convention, it would have to be named "nonlocal".

Then, some substructures of objects, say quarks inside protons, would be covered by Bell's theorem as well. One cannot circumvent Bell's theorem by inventing further substructures of the quarks. Such substructures would be some well-defined ontology too, one could describe them with some $\lambda \in \Lambda$.

 

[vanhees71]

Well, if the limiting speed would be much larger than $c$ this would simply mean that light is not described by massless (quantum) fields but by massive ones, and we'd call that limiting speed not "speed of light" but somehow else.

 

[DarMM]

How would you name a theory so that all objects have localization in space, there is also a maximal speed, but one much higher than c?

Bell's theorem also rules that out. In nonlocal theories the signalling has to be instantaneous.

 

[Elias1960]

Bell's theorem also rules that out. In nonlocal theories the signalling has to be instantaneous.

Not really. All one can conclude from Bell's theorem is that the predictions of such a theory cannot be exactly the same as those of QM.

But exact equivalence to QM is not a Holy Grail. What made Bell's theorem interesting is that it allowed to falsify empirically all Einstein-causal realistic theories. Because all that was necessary was to prove that the maximal speed of information transfer has to be higher than c.

But there is clearly no base for hope that one can empirically falsify all local realistic theories. t sufficient to empirically falsify such theories. All one can hope for are results like the maximal speed of information transfer has to be larger than, say, $10^4 c$ (as already obtained) or $10^{400} c$ (which will be unreachable). So, such theories are not ruled out at all.

 

[DarMM]

Well if we're admitting that QM might be wrong, then yes such theories are not ruled out.

 

[Elias1960]

Well, if the limiting speed would be much larger than $c$ this would simply mean that light is not described by massless (quantum) fields but by massive ones, and we'd call that limiting speed not "speed of light" but somehow else.

Not plausible. If light would be massive, we would observe it having very different speeds depending on the momentum. Except if all the light we can observe has already such a high momentum in comparison with its mass that the velocity would be, even if lower than $c$, practically indistinguishable from c. And this could be the case only if $c$ remains almost $c$ and the mass is very small.

A theory with a much larger limiting speed would not necessarily be a relativistic field theory. Even if this would be quite plausible that there would be also some Lorentz group playing a role, given that the Lorentz group is the symmetry group of essentially every wave equation.

But the SM fields and gravity would remain to follow the Einstein equations, with good old c as the limiting speed. The higher speeds would be some other, quantum, effects. And if that higher speed Lorentz group would play a fundamental role would be unclear. It would not necessarily be universal and without universality no fundamental Lorentz symmetry.

 

[vanhees71]

Exactly that's what I'm saying. The assumption of a much larger limiting speed than the speed of light is speculative, given the evidence for photons being precisely massless. Of course the experimental "proof" is only a very small upper bound for a putative photon mass, which is (according to the PDB 2018: $m_{\gamma}<1 \cdot 10^{-18} \; \text{eV}/c^2$). Thus to claim that there might be a much large "limiting speed" of relativity is overly speculative (to put it friendly ;-)). There's not the slightest evidence whatsoever for such speculative "alternate theories".

 

[Elias1960]

Exactly that's what I'm saying. The assumption of a much larger limiting speed than the speed of light is speculative, given the evidence for photons being precisely massless.
There's not the slightest evidence whatsoever for such speculative "alternate theories".

Sorry, but the massless photons give you nothing in this regard.

A simple example would be some transparent condensed matter where the sound is described by a simple wave equation. Then, the corresponding phonons would be massless. But light would have nonetheless a much larger velocity that these phonons.

And "not the slightest evidence", seriously? More serious evidence that violations of the Bell inequality are not necessary at all. You have to reject realism as well as causality. But if you do this, and seriously (not only in the single case of Bell inequality violations) no empirical evidence will be ever able to prove anything.

 

[Demystifier]

Exactly that's what I'm saying. The assumption of a much larger limiting speed than the speed of light is speculative, given the evidence for photons being precisely massless. Of course the experimental "proof" is only a very small upper bound for a putative photon mass, which is (according to the PDB 2018: $m_{\gamma}<1 \cdot 10^{-18} \; \text{eV}/c^2$). Thus to claim that there might be a much large "limiting speed" of relativity is overly speculative (to put it friendly ;-)). There's not the slightest evidence whatsoever for such speculative "alternate theories".

That's indeed speculative, but the opposite claim is speculative too. Claiming that relativity theory is valid at all circumstances, including those that are far from the circumstances in currently existing experiments, is speculative too. Is relativity valid at the Planck distance? If one says no, it's speculative. If one says yes, that's speculative too.

 

[martinbn]

That's indeed speculative, but the opposite claim is speculative too. Claiming that relativity theory is valid at all circumstances, including those that are far from the circumstances in currently existing experiments, is speculative too. Is relativity valid at the Planck distance? If one says no, it's speculative. If one says yes, that's speculative too.

To me there is a big difference. Relativity theory is a concrete and specific theory that allows you to solve problems, and has been tested quite extensively. Saying may be it isn't fundamental, or may be it doesn't hold at all scales etc. is, in my opinion, a lot more speculative. In fact it is pointless, because it is just wishfull thinking. It is not enough to say may be it isn't so. You need to at least give enough detail to be able to actually do something with it. Otherwise it is in the same catogory as Russel's teapot.

 

[Elias1960]

To me there is a big difference. Relativity theory is a concrete and specific theory that allows you to solve problems, and has been tested quite extensively. Saying may be it isn't fundamental, or may be it doesn't hold at all scales etc. is, in my opinion, a lot more speculative. In fact it is pointless, because it is just wishfull thinking. It is not enough to say may be it isn't so. You need to at least give enough detail to be able to actually do something with it. Otherwise it is in the same catogory as Russel's teapot.

Sorry, but we know that GR as it is is wrong, because it is not a quantum theory. The straightforward use of standard field-theoretic methods gives an effective field theory on a fixed flat background, but this effective field theory is not renormalizable, thus, fails below a critical length. For this critical length we have a well-motivated guess, Planck length.

So there is no "maybe" about GR being not fundamental, it is known not to hold on all scales. And the wishful thinking for a background-independent quantum theory of gravity is on the other side. (In comparison, as a background-dependent QG every more or less plausible regularization of the field theory gives a well-defined candidate.)

 

[PeterDonis]

we know that GR as it is is wrong, because it is not a quantum theory

This assumes that every fundamental theory must be a quantum theory. But that claim itself is also speculative. Most physicists seem to believe it, but that's not the same as actually having evidence for it. (At least one physicist, Freeman Dyson, has IIRC argued that it's possible that there is no quantum theory of gravity, and GR is the most fundamental theory of gravity there is.)

there is no "maybe" about GR being not fundamental, it is known not to hold on all scales

"Known" is much too strong here. We have no evidence that GR fails on any scale. We only have various theoretical arguments that most physicists believe are valid, but which have not been tested (and can't be tested unless and until we figure out how to probe distance scales 20 orders of magnitude smaller than the ones we can probe now).

 

[DarMM]

Also in general it becomes impossible to say anything if every statement about QM has to be appended with 40,000 clauses to prevent "But, but, but what if relativity is wrong, what if QM is wrong, what if spacetime is only the shell of a giant turtle"

 

[Nugatory]

Also in general it becomes impossible to say anything if every statement about QM has to be appended with 40,000 clauses to prevent "But, but, but what if relativity is wrong, what if QM is wrong, what if spacetime is only the shell of a giant turtle"

Yes indeed, and that’s one reason we have the words “as it is currently generally understood and practiced by the professional scientific community” in the mission statement. There’s quite enough complexity just in the mainstream discussion of issues raised in the first post of this thread.

 

[Elias1960]

This assumes that every fundamental theory must be a quantum theory. ... (At least one physicist, Freeman Dyson, has IIRC argued that it's possible that there is no quantum theory of gravity, and GR is the most fundamental theory of gravity there is.)

Ok, let's reformulate: We know that GR, in its current form, is wrong because it is unable to describe quantum effects.

"Known" is much too strong here. We have no evidence that GR fails on any scale. We only have various theoretical arguments that most physicists believe are valid, but which have not been tested (and can't be tested unless and until we figure out how to probe distance scales 20 orders of magnitude smaller than the ones we can probe now).

I agree, but theoretical arguments are not completely worthless. And some aspects of theoretical arguments (in particular, conflicts between theoretical principles) do not depend on empirical support.

Also in general it becomes impossible to say anything if every statement about QM has to be appended with 40,000 clauses to prevent "But, but, but what if relativity is wrong, what if QM is wrong, what if spacetime is only the shell of a giant turtle"

But there is no need to append such things every time. Here, the subdiscussion started with the question that "local" should be named "Einstein-local", given that there are obviously local theories with maximal speed higher than c and to use a convention that forces one to name such theories "non-local" would be Orwellian. And theories different from QM are the very question considered in Bell's theorem too. So, given this context of the discussion, considering these questions here seems justified.

 

[PeterDonis]

We know that GR, in its current form, is wrong because it is unable to describe quantum effects.

That doesn't mean it's wrong, just that it's incomplete. So is our best quantum theory to date, the Standard Model, since it doesn't include gravity. We don't have any complete theory at this point.

theoretical arguments are not completely worthless

That may be true, but having a theoretical argument and nothing else is not the same as knowledge, and my objection was to your use of the word "known".

some aspects of theoretical arguments (in particular, conflicts between theoretical principles) do not depend on empirical support

They do if you want to actually resolve them. Otherwise you just have conflicting theoretical arguments and no evidence either way.

 

[vanhees71]

Sorry, but the massless photons give you nothing in this regard.

A simple example would be some transparent condensed matter where the sound is described by a simple wave equation. Then, the corresponding phonons would be massless. But light would have nonetheless a much larger velocity that these phonons.

And "not the slightest evidence", seriously? More serious evidence that violations of the Bell inequality are not necessary at all. You have to reject realism as well as causality. But if you do this, and seriously (not only in the single case of Bell inequality violations) no empirical evidence will be ever able to prove anything.

You have to decide what you claim.

(a) The standard physics (which is very well empirically established)

Photons are massless. The electromagnetic interaction propagates with the limiting speed, usually thus called "the speed of light"

(b) Your personal hypothesis (not in any way established empirically and thus fictitious)

Photons are not massless. The electromagnetic interaction does not propagate with the limiting speed, and thus the limiting velocity is some other larger value than "the speed of light in vacuum".

You cannot have both massless photons and a limiting speed greater than the speed of light.

The violation of Bell's inequality does not contradict this since it has nothing to do with faster-than-light causal influences whatsoever. Relativistic local QFT is the framework upon which the Standard Model is constructed, which is in accord with case (a) and nothing else.

If you want to claim otherwise you have to open another thread in the new "foundations" subforum!

 

[Elias1960]

You cannot have both massless photons and a limiting speed greater than the speed of light.

I can, and I have already given you an example.

Some sufficiently rigid condensed matter, with a wave equation $\square u = 0$ as the equation for sound waves. The phonons of the corresponding quantum condensed matter theory will be massless and have the speed of sound. Nonetheless, there are other things (like light) in this theory that have a much larger speed. So, the speed of sound is not the limiting speed of information transfer.

If you want to claim otherwise you have to open another thread in the new "foundations" subforum!

My original point was about how to name a class of theories that quite obviously can exist. Those theories are local, in any reasonable meaning of local, but they would have to be named nonlocal if one incorrectly abbreviates "Einstein-local" as "local". Your claim that such theories cannot exist is obviously wrong, and my counterexample to your claim is standard condensed matter theory, where you can have massless phonons despite the speed of sound not being the speed limit for information transfer.

 

[vanhees71]

Sound waves have a much lower propagation speed, the speed of sound. Phonons are not massless. I don't know, what you want to prove with this argument.

 

[Elias1960]

Sound waves have a much lower propagation speed, the speed of sound.

Which is the point of the analogy. If there would be a much larger maximal speed of information transfer than c, the speed of light would be an analogon of what is the speed of sound.

Phonons are not massless. I don't know, what you want to prove with this argument.

To quote Wiki-level information:

The speed of propagation of an acoustic phonon, which is also the speed of sound in the lattice, is given by the slope of the acoustic dispersion relation, ∂ωk/∂k (see group velocity.) At low values of k (i.e. long wavelengths), the dispersion relation is almost linear, and the speed of sound is approximately ωa, independent of the phonon frequency.

Thus, in the long-distance limit the acoustic phonons are massless.

The analogy is quite complete, we have a maximal speed of information transfer much larger than the speed of sound, but nonetheless, the acoustic phonons have a speed independent of their frequency as if they were massless particles. What is possible for sound, will be possible for light too, thus, it is not impossible that there is a maximal speed of information transfer much larger than the speed of light, and that the speed of light does not depend on its frequency is not a valid counterargument. So, your argument is invalid.

Here for reference your claims which I reject:

if the limiting speed would be much larger than c this would simply mean that light is not described by massless (quantum) fields but by massive ones
...
You cannot have both massless photons and a limiting speed greater than the speed of light.

 

[Demystifier]

Phonons are not massless.

Yes they are. In the long distance (low energy) limit they obey the dispersion relation
$$\omega^2=c_s^2{\bf k}^2$$
where $c_s$ is the speed of sound. For comparison, photons obey the dispersion relation
$$\omega^2=c^2{\bf k}^2$$
where $c$ is the speed of light.

 

[vanhees71]

If you'd interpret this as "massless", then you'd have tons of "limiting speeds", which is obviously utter nonsense. There's one limiting speed, and that's the speed of light in a vacuum. The speed of a phonon is $c_s<c$ and thus the phonon is not massless.

 

[Demystifier]

If you'd interpret this as "massless", then you'd have tons of "limiting speeds", which is obviously utter nonsense.

Well, we have many limiting speeds in EU. The limiting speed on German highways is much larger than in the rest of EU. Do you think it's utter nonsense?

Now seriously, the point is that there is no logical contradiction in a possibility that there are different limiting speeds for different objects in different conditions.

There's one limiting speed, and that's the speed of light in a vacuum.

That is indeed so in the Standard Model. But since the Standard Model is just an effective theory, it may not be so at some more fundamental level. Now you will say that there is no any direct experimental evidence for that, but there is at least an indirect one. The experimental violation of Bell inequalities is an indirect evidence that there may exist some influences traveling with an infinite speed. Yes, it's just a hint, an indirect evidence, but it's evidence nonetheless.

The speed of a phonon is $c_s<c$ and thus the phonon is not massless.

So what's the phonon's mass then?

 

[vanhees71]

Let's first get clear what I'm saying: There's one limiting speed in the sense of relativity theory, and that's the speed of light in a vacuum and nothing else.

Phonons are quasiparticles in a medium. That they have formally 0 mass does not mean that there are more then one "limiting speeds" in the sense of relativity.

 

[martinbn]

Now seriously, the point is that there is no logical contradiction in a possibility that there are different limiting speeds for different objects in different conditions.

But if you need an infinite speed of propagation you will run into a problem with relativity that you cannot sweep under the rug "may be relativity isn't exact at other scales". It will be in conflict with tested corollaries.

 

[Demystifier]

Let's first get clear what I'm saying: There's one limiting speed in the sense of relativity theory, and that's the speed of light in a vacuum and nothing else.

Phonons are quasiparticles in a medium. That they have formally 0 mass does not mean that there are more then one "limiting speeds" in the sense of relativity.

I think nobody here doubts that.

 

[Demystifier]

But if you need an infinite speed of propagation you will run into a problem with relativity that you cannot sweep under the rug "may be relativity isn't exact at other scales". It will be in conflict with tested corollaries.

What "tested corollaries" do you have in mind?

 

[vanhees71]

I think nobody here doubts that.

No, there was the claim that there may be another much larger limiting speed than the speed of light in the sense of relativity. That's of course utter nonsense!

 

[Demystifier]

No, there was the claim that there may be another much larger limiting speed than the speed of light in the sense of relativity. That's of course utter nonsense!

I think you misunderstood the claim. It was meant in a sense of generalized relativity. See e.g. my "Bohmian mechanics for instrumentalists", Sec. 5.3.

 

[PeterDonis]

there is no logical contradiction in a possibility that there are different limiting speeds for different objects in different conditions

There might be in the presence of additional premises.

In the context of relativity, isn't there a theorem that there can be at most one finite limiting speed? In other words, that given the principle of relativity, the only two possibilities are Galilean spacetime (no finite limiting speed) and Lorentzian spacetime (one finite limiting speed)?

 

[Elias1960]

[Moderator's note: Rule violation content deleted.]

In the context of relativity, isn't there a theorem that there can be at most one finite limiting speed?

In a discussion about hidden variable theories for quantum theory, the context is not that of relativity.

And you certainly have to make assumptions about the fundamental character of relativistic symmetry. They are necessarily metaphysical, which means, they cannot be supported by observation alone. Else, we have the equations for sound waves, which may be (say, for low-frequency acoustic phonons) $\square u = (\frac{1}{c_{sound}^2}\partial_t^2 - \Delta) u = 0$. This equation, and, therefore, some part of the equations describing this universe, has, then, "relativistic" symmetry with $c_{sound}$ instead of c as the speed used in the Lorentz transformation.

[Moderator's note: Rule violating content deleted.]

 

[PeterDonis]

All you have to do is to go back to the Lorentz ether

This is out of bounds for PF discussion. Please do not mention it again or you will receive a warning.

 

[PeterDonis]

This is out of bounds for PF discussion. Please do not mention it again or you will receive a warning.

I have edited the post to remove the out of bounds content.

 

[PeterDonis]

In a discussion about hidden variable theories for quantum theory, the context is not that of relativity.

The "context of relativity" here means the basic principle of relativity, that the laws of physics are the same in all frames. It does not mean "relativity" in the sense of the specific theory of SR.

you certainly have to make assumptions about the fundamental character of relativistic symmetry. They are necessarily metaphysical, which means, they cannot be supported by observation alone

But they can be adopted as the simplest assumptions consistent with the experimental facts. If you are going to assume that the principle of relativity is violated, you need to show some evidence that it is. There is no such evidence.

Else, we have the equations for sound waves

Sound waves in a material substance which can be observed, and its properties measured, independently of the propagation of sound. The speed of sound is a property of the substance, not of the laws of physics. The principle of relativity in no way forbids substances from having particular properties.

 

[bhobba]

The "context of relativity" here means the basic principle of relativity, that the laws of physics are the same in all frames. It does not mean "relativity" in the sense of the specific theory of SR.

Of course. But just to further expand on it ordinary QM is based on the Galilean Transformations that strictly speaking allows an infinite speed. Of course its not true, and is just an approximation, but as found in chapter 3 of Ballentine (where he proves Schrodinger equation etc - yes it can be proven if you have never seen it) that is a, perhaps hidden, assumption of normal QM. The reason I say perhaps hidden is my go-to book on QM is Ballentine and it makes it clear - those not exposed to it may not realize it. So those that use locality as an argument in ordinary QM strictly speaking should use QFT. However I can't say it really has caused much if any issues in posts here or books I have read so likely its just being pedantic. Perhaps that's because, like the Galilean transformations themselves, its a limit of QFT, and interpretations etc discussed here usually (but not always) are not affected by it. I will however say in analysing Bell I like to keep in mind the cluster decomposition property of QFT - but that requires a whole new thread that I think may still be going on.

Thanks
Bill

 

[bhobba]

In a discussion about hidden variable theories for quantum theory, the context is not that of relativity.

Not always.

And you certainly have to make assumptions about the fundamental character of relativistic symmetry. They are necessarily metaphysical

No they are experimental. Its not really on topic for this thread but to understand SR you really need to see a modern derivation of it:
http://www2.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf
The constant c that appears in the equations can be, and has been, determined in many ways and all are in agreement. If you want to discuss it further please start a new thread - its not appropriate here.

Just a note, as a moderator, explaining why, by forum rules, we do not discuss LET here, except in a historical context. The modern view of SR is very clear, and illustrative of modern physical ideas of the importance of symmetry. The forum rules are, in part, to stop threads that by their very nature would not really go anywhere.

Thanks
Bill

 

[Elias1960]

No they are experimental. Its not really on topic for this thread but to understand SR you really need to see a modern derivation of it:
http://www2.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf

This "modern derivation" does not present anything at all which would suggest that general assumptions about fundamental symmetries are somehow experimental. They cannot be by their very nature. Experiments give only approximate results, and so they cannot allow, even in principle, to distinguish fundamental symmetries from approximate symmetries. (Ok, except in the case when the approximate character follows already from the experimental data.)

The constant c that appears in the equations can be, and has been, determined in many ways and all are in agreement.

As if somebody has questioned the measurements of the speed of light.

Just a note, as a moderator, explaining why, by forum rules, we do not discuss LET here, except in a historical context. The modern view of SR is very clear, and illustrative of modern physical ideas of the importance of symmetry. The forum rules are, in part, to stop threads that by their very nature would not really go anywhere.

Metaphysical ideas about the importance of symmetries are already quite old now, they were modern 1905 or so. And, in fact, symmetries have always impressed people, in particular, mystics. If you prefer threads going into something wrong given that you forbid certain types of counterarguments (with your "they are experimental" as an example), your choice.

 

[martinbn]

What "tested corollaries" do you have in mind?

Just clarify what I mean by infinite speed of propagation, and what the standard terminology is as far as I understand it. If the electromagnetic field had infinite speed of propagation, then the compas needle over there would move the instant there is current in the wire over here, no matter how far apart they are. So, why do you think that this, for any field, would not be in conflict with relativity and experiment? By the way, why do you put "" around tested corollaries? Are you claiming that there aren't any?

 

[vanhees71]

So those that use locality as an argument in ordinary QM strictly speaking should use QFT.

They should use relativistic QFT. If you want to discuss locality you can never argue with non-relativistic approximations, because there's nothing in Galileo-Newtonian physics which guarantees locality, and already in the Theoretical Physics 1 quite in the beginning we violate it when we write down Newton's Law of gravity. There's nothing wrong with that, but as you rightly say, it's an approximation with some limited range of applicability. It's well applicable within the solar system, but there are also deviations from it known already in the 19th century (perihelion shift of Mercury).

 

[bhobba]

This "modern derivation" does not present anything at all which would suggest that general assumptions about fundamental symmetries are somehow experimental.

What about, for example, the laws of physics is the same in all inertial frames or frames moving at constant velocity to an inertial frame. What is not experimentally verifiable about that?

Experiments give only approximate results, and so they cannot allow, even in principle, to distinguish fundamental symmetries from approximate symmetries. (Ok, except in the case when the approximate character follows already from the experimental data.)

We all know the game of science - we can never prove a conjecture by experiment, only check if the experiment supports it.

As if somebody has questioned the measurements of the speed of light.

The exact speed is not the issue - it's what is said in the paper:
'Knowing about the Maxwell equations and electromagnetic waves, we can identify this parameter with the speed of light.'

In fact it can be detailed further by showing that c can be made part of a derivation of Maxwell's equations:
http://cse.secs.oakland.edu/haskell/Special Relativity and Maxwells Equations.pdf

Metaphysical ideas about the importance of symmetries are already quite old now, they were modern 1905 or so. And, in fact, symmetries have always impressed people, in particular, mystics. If you prefer threads going into something wrong given that you forbid certain types of counterarguments (with your "they are experimental" as an example), your choice.

We forbid very few things here. Yes LET is forbidden - but that's only because it is well and truly superseded so is confined to its historical context. But regarding symmetries being metaphysical and requiring interpretation what about the modern definition of energy as the conserved quantity implied by Noethers Theorem and time invarience?. Is energy just 'metaphysical'? Does the theorem need interpretation - its rather explicit. But please do not post in this thread, start another thread if you want to delve into it further.

Thanks
Bill

 

[Elias1960]

What about, for example, the laws of physics is the same in all inertial frames or frames moving at constant velocity to an inertial frame. What is not experimentally verifiable about that?

Everything. It is a general statement, and general hypotheses cannot be verified by experiments. They can only be falsified.

We all know the game of science - we can never prove a conjecture by experiment, only check if the experiment supports it.

So why you make, then, claims about such conjectures being verifiable?

The exact speed is not the issue - it's what is said in the paper:
'Knowing about the Maxwell equations and electromagnetic waves, we can identify this parameter with the speed of light.'

The point being? It was never a problem to derive the Lorentz symmetry from some general metaphysical hypotheses.

We forbid very few things here. Yes LET is forbidden - but that's only because it is well and truly superseded so is confined to its historical context.

It is certainly not superseded by any experimental fact.

But regarding symmetries being metaphysical and requiring interpretation what about the modern definition of energy as the conserved quantity implied by Noethers Theorem and time invarience? Is energy just 'metaphysical'?

First, mathematics is mathematics, theorems do not need interpretations. But if a given symmetry is fundamental or approximate, and if everything is symmetric or only some part of objective reality, requires interpretation. If time translation invariance is only approximate, then I would expect that energy conservation will be only approximate too. About the metaphysical questions related to energy, I would recommend you to inform yourself in discussions about energy-momentum pseudotensors in GR.

But please do not post in this thread, start another thread if you want to delve into it further.

I answer questions where they appear. I don't want to delve into this further, but once you continue - I don't like to create the impression that I have no answers to such questions.

 

[bhobba]

Everything. It is a general statement, and general hypotheses cannot be verified by experiments.

We all can channel Popper. However physics goes beyond the philosophy of science and actually accepts some things. When a physicist says something general has been experimentally verified what is meant is sufficient experimental proof exists that its generally accepted as correct. That of course does not prove it, but to make progress you have to accept something - even though you know its provisional. I am sure you have read Popper - I suggest also reading Feynman The Character Of Physical Law and The Feynman Lectures.

BTW discussion of Philosophy is not allowed here. The reason is we do not have a mentor suitably qualified in both philosophy and science/engineering to moderate it. We did once but when they left it got out of hand and we had to bar it. A friendly warning from a mentor if that is what you want to discuss this may result in action taken.

First, mathematics is mathematics, theorems do not need interpretations.

That's the point I am making. Both Noether's Theroem and the modern justification of SR are theorems based on assumptions. In a mathematical theorem you state your assumptions and get a result. If the assumptions are true, and for the theorems discussed here they are true in the sense elucidated above, then the the result is also true. I will leave you to nut out what the physical assumption is that goes in Noether's theorem. The point is to doubt SR you have to doubt what went into it and that has very strong support. We do not need any kind of interpretation of SR - it's simply a consequence of things generally accepted as true.

Thanks
Bill

 

[Elias1960]

BTW discussion of Philosophy is not allowed here.

Facepalm. A physics forum where one is not allowed to discuss the scientific method.

The reason is we do not have a mentor suitably qualified in both philosophy and science/engineering to moderate it.

The only question which remains is if this only a particular accidental situation in the moderation team here, or is this simply the general situation in modern physics? In fact, I would tend to the second answer - a complete lack of education about methodology, a strong prejudice against discussions of interpretations in general, and questioning the spacetime interpretation of relativity being anathema seems widely distributed.

But I guess that discussing such general questions will be forbidden here too. Not?

 

[PeterDonis]

A physics forum where one is not allowed to discuss the scientific method.

He didn't say "scientific method". He said "philosophy". They're not the same thing.

I guess that discussing such general questions will be forbidden here too. Not?

We generally do not allow discussions on topics that are simply assertions of opinion, since there is never any resolution to such discussions; people just continue asserting their opinions.

PF's mission is to help people understand mainstream science. To the extent that there is actual mainstream scientific research about how science is done, discussion of it would be allowed here. But bare statements of personal opinion do not qualify.

 

[Elias1960]

He didn't say "scientific method". He said "philosophy". They're not the same thing.

Yes, but the discussion of the scientific method is part of discussing philosophy.

We generally do not allow discussions on topics that are simply assertions of opinion, since there is never any resolution to such discussions; people just continue asserting their opinions. PF's mission is to help people understand mainstream science.

There are a lot of quite precise arguments made, in particular, by Popper, which are beyond the "simply assertions of opinion". And how can one understand mainstream science without understanding at least the basic concepts of Popper's critical rationalism as well as the problems of empiricism/positivism?

 

[PeterDonis]

but the discussion of the scientific method is part of discussing philosophy

That doesn't mean we need to allow other parts of philosophy besides that one.

There are a lot of quite precise arguments made, in particular, by Popper, which are beyond the "simply assertions of opinion".

I wasn't talking about Popper's assertions. I was talking about yours.

how can one understand mainstream science without understanding at least the basic concepts of Popper's critical rationalism as well as the problems of empiricism/positivism?

Many people seem to manage it quite well. Perhaps they don't meet your personal criterion of "understanding", but they can use mainstream science to make accurate predictions.

At the end of the day, the PF rules are what they are, and they are there for reasons, many of which have to do with trying certain kinds of discussions in the past and having them not work. If you want to suggest a change to the PF rules, you should open a thread in the Feedback forum and make your argument. But you should be prepared for the final answer after consideration to be no. For further discussion in this thread, rules are off topic; please stick to the actual thread topic.

 

[bhobba]

Facepalm. A physics forum where one is not allowed to discuss the scientific method.

The scientific method is part of philosophy - sure - it is also part of science with many scientists like Feynman discussing it. Interestingly they often come to different conclusions than actual philosophers. See the following by Wienberg:
https://www.physics.utah.edu/~detar/phys4910/readings/fundamentals/weinberg.html
You can discus the scientific method here. If it strays too much into philosophy some gentle reminders will be posted by mentors to get it back on track.

The only question which remains is if this only a particular accidental situation in the moderation team here, or is this simply the general situation in modern physics? In fact, I would tend to the second answer.

Those of a philosophical bent often say that here, and elsewhere. I once posted a lot on alt.sci.physics.relativty. Actual scientists like John Baez and Steve Carlip also posted. A very high percentage of posts was they thought physics lost its way because it ignored philosophy. We even had a post here that because PhD stands for Doctor of Philosophy scientists were ignoring their training thinking a PhD meant the doctorate was actually in philosophy. Those more influenced by Feynman, Dirac etc disagree. All I will say is it would seem those in the second group have made more progress, but those in the first group still have produced interesting scientific work such as David Wallace who has a PhD in both philosophy and particle physics:
https://www.amazon.com/dp/0198707541/?tag=pfamazon01-20

I have read the above book, but interestingly, for me, it shed more light on Decoherent Histories as advocated by Gell-Mann, and I think Feynman was converted to it towards the end. Still it's a legitimate book to discuss here.

Thanks
Bill