The Strand Model of fundamental interactions

[physics8553]

Since you declare that we have to choose an "observer", does this "choice" lead to "landscape" type problems, like in string theory? Ie. is your "choice" of "background" needed for your theory, sufficiently unique to guarantee specific predictions, rather than whole familities of predictions?

Ie. what additional trick/constraint do you use, to "constrain" the set of possible backgrounds/observers - and thus - the set of possible predictions for interactions?

Frederik, there are no landscape problems in the strand model, because there are no higher dimensions. Since there are only three spatial dimensions, the vacuum state is uniquely defined.

Indeed, the predictions are specific to this property. If more than 3 dimensions exsisted, no predictions would be possible. For example, there are only three interactions, with gauge groups U(1), SU(2) and SU(3), because we live in 3 dimensions. (The arguments uses the three Reidemeister moves.) And there are only three generations of elementary particles, because we live in 3 dimensions. (The arguments uses the various tangle families that are possible in 3 dimensions.) And the gauge coupling constants, masses and mixings also follow uniquely only because there are 3 dimensions.

In other words, no restriction of observers is necessary (except the usual ones: that it must be made of matter and interact with help of radiation.)

 

[physics8553]

Christoph, in your 6th volume you state that wave functions are "blurred" strands. Has anybody else explored this? Blurring of strands is such a simple model for wave functions that many researchers must be interested. Can you point to some papers on this?

Heinz, wave functions are blurred strands, but the blurring is not trivial: the crossing positions are blurred, not the strands themselves. This is important.

I looked through the literature and did not find anything on the matter. I found some ideas on polymers and evolution equations similar to the Schrödinger equation, but nothing of the type you ask for. Of the people that tried to model wave functions, nobody seems to have though about strands and tangles - except of course, Battey-Pratt and Racey in 1980. But their ideas did not catch on. Racey wrote to me saying that they tried to ask Dirac about this, but Dirac never answered. What a pity!

Do you have something specific in mind?

 

[physics8553]

So that's what I'm saying about this drive in physics for a TOE. How do we know "the creator" (whatever that refers to, maybe nothing) didn't use multiple "tools" to cook up and operate the universe.

My own opinion is: physics is talking about observations. The aim to find a unified description is the aim to find the correct concepts for this description. There seems to be no reason a priori why this should be impossible. And we also know that general relativity and quantum theory contradict each other; so we know that the present concepts are not the correct ones. This is the riddle.

 

[physics8553]

If a researcher succeeds, he is the greatest of all time. If he fails, he is a crackpot. This alternative is not very appealing; it is like chosing between Scylla and Charybdis.

A nice analogy - I think I will use it every now and then!

 

[physics8553]

So for example, if you had a complex mathematical description of force, that was consistent, explained various observations, and had as it's central tenet that angels on little winged horses were the "carrier" of force, I'd say you've described nothing if you can't use your angel-horse theory to build a bridge. And that's what I'm thinking might be happening with these extravagant TOE. (Not that physicists shouldn't try to come up with TOE, just that they have to be careful not to stray into angel-horse land.)

The best way to avoid this trap is to ensure that the theory is unmodifiable. The final theory must be of a sort that cannot be varied, modified, generalized, or simplified. The strand model is appealing because it seems to fulfill this requirement. And of course, it predicts 3 gauge forces, 3 particle generations, and the weak mixing angle.

 

[physics8553]

yes, like 'How does magnetism work(mechanisms behind it) and create a dual field at both poles?'

Magnetism is relativistic electricity. To understand poles, one needs to understand electric charge. The strand model has a simple explanation for electric charge: it results from the chirality of the matter tangles that describe charged elementary particles. The chirality is conserved, has to signs, moves slower than the speed of light - all properties that electric charges have. More details of how strands define magnetic fields are given in the text on http://www.motionmountain.net/research/index.html (see the drawing on page 198 and the text around it).

 

[rewebster]

Magnetism is relativistic electricity. To understand poles, one needs to understand electric charge. The strand model has a simple explanation for electric charge: it results from the chirality of the matter tangles that describe charged elementary particles. The chirality is conserved, has to signs, moves slower than the speed of light - all properties that electric charges have. More details of how strands define magnetic fields are given in the text on http://www.motionmountain.net/research/index.html (see the drawing on page 198 and the text around it).

nice drawing---


however, it and the text still do not explain how magnetism works and why there is the duality at the poles----in other words, there is no explantion of the mechanisms.

 

[Fra]

Frederik, there are no landscape problems in the strand model, because there are no higher dimensions. Since there are only three spatial dimensions, the vacuum state is uniquely defined.
...
In other words, no restriction of observers is necessary (except the usual ones: that it must be made of matter and interact with help of radiation.)

Would you say that the set of all possible physical - and thus "allowed" - observers can be generated from some kind of "strand construction" including the construction rules of yours? And that from this you can find the observer-observer transformations that restores a "unique" observer-invariant equivalence class of say vacuum state?

I don't understand your motivation for the strands but I'm trying to connect to find a way to connect to your general construction that is "strand-indepdenent" :)

/Fredrik

 

[physics8553]

(1)Would you say that the set of all possible physical - and thus "allowed" - observers can be generated from some kind of "strand construction" including the construction rules of yours?

(2) And that from this you can find the observer-observer transformations that restores a "unique" observer-invariant equivalence class of say vacuum state?

(3) I don't understand your motivation for the strands but I'm trying to connect to find a way to connect to your general construction that is "strand-indepdenent" :)

/Fredrik

(1) Yes. Observers are made of matter and contains baths: they are made of many particles. Each particle is a tangle.

(2) Yes. The vacuum state(s) is that class of strands tangles that correspond roughly to what you get when you through long spaghetti into boiling water: lots of wobbling spagehtti, but no knots.

(3) The motivations for strands are various: strand crossings can be used to define wave functions, 3-d space, curvature, and gauge fields. And strands reproduce horizons and black hole entropy. Strands reproduce the Dirac equation and the field equations of general relativity, if the strands are averaged out. Then, strands reproduce the three gauge interactions and the three particle generations. There are not many models that provide all this. In addition, the strand model is simple and impossible to vary. That makes is a good candidate for a unified description.

To be honest, if the strand model is correct, the question of the motivation can be answered in many ways, depending on personal taste. In fact, if it is correct, it is a simple model that is "hard to vary".

Maybe you meant to ask why the basic blocks are strands, and thus extended. Well, one reason is that extended constituents allow to deduce black hole entropy, holography, 3d space, and all related properties. (This is impossible with constituents that are not extended.) Another reason is that extension allows to relate topology and shape with physical observables. (Again, this is impossible without extension.) Still another reason: many people have speculated that non-commutativity in quantum theory is consequence of some topological process; strands confirm this.

 

[physics8553]

nice drawing---


however, it and the text still do not explain how magnetism works and why there is the duality at the poles----in other words, there is no explantion of the mechanisms.

This is an issue of classical electrodynamics, not of unification! Magnetic poles are consequences of the lack of magnetic monopoles, and of the motion of electric charges. Magnets have two poles because the charges inside them move and spin. Any model that contains electric charges that follow Coulomb's law thus explains the two poles of a magnet.

"Magnetism is relativistic electricity." One place where to read about this, in particular about how magnetism appears from Coulomb's law, is the third volume of my Motion Mountain physics text, found at www.motionmountain.net. But almost all textbooks on electrodynamics tell how magnetic poles appear.

 

[DrChinese]

Christoph,

I am enjoying your fascinating paper. Nice to see something with some predictions!

I have a few questions about entanglement. From your book, circa pages 176/177:

"A second example is the entanglement of two photons, the well-known Aspect experiment. Also in this case, entangled spin 0 states, i.e., entangled states of photons of opposite helicity (spin), are most interesting. Again, the strand model helps to visualize the situation.We use the strand model for the photon that we will deduce later on. Figure 32 shows the strand model of the two separable basis states and the strand model of the entangled state. Again, the measurement of the helicity of one photon in the entangled state will lead to one of the two basis states. And as soon as the helicity of one photon is measured, the helicity of its companion collapses to the opposite value, whatever the distance! Experimentally, the effect has been observed for distances of many kilometres. Again, despite the extremely rapid collapse, no energy travels faster than light. And again, the strand model completely reproduces the observations."

OK, I think I follow this. The strands are connected, the basis change instantaneous. Nice. But entanglement has some funny properties, and I would like to extend this example a bit to flesh that out if that is acceptable.

So we have Alice and Bob, several kilometers apart. At any polarizing beam splitter (PBS) angle setting they choose which is identical, their results (in an ideal world) will be perfectly correlated. We are in agreement here, and I will call this the i) case. Time stamps are made of arrivals at Alice and Bob's detectors, and suitable pairs within a suitable coincidence window will be considered only. This technique will be used in all cases discussed here, regardless of how many are seen in any period of time. All we care about is the percentage of correlations, not the absolute number. Alice and Bob hold their angle settings fixed in all cases below.

i) With suitable choice of settings, the correlation is 100%. Bell inequalities are also violated, showing that the photon pair is not only EPR entangled but also violates Bell inequalities (and local realism).

Now, I insert a black box in Alice's path, but not Bob's. I have in fact 2 black boxes which do 2 different things, which I will label cases ii) and iii) below. Again, in all cases, I will make note of time stamps of arrivals at Alice and Bob - considering that the distances traveled may not be equal but we will always calibrate so that proper pairs are matched.

ii) My black box contains a PBS - set 45 degrees offset from Alice - so that one channel is detected there and the other channel is passed on through the black box to Alice. I know which path the photon takes because it either clicks a photodetector or passes through. Obviously, only half the photons make it through to but that will not matter to the final observed number as we are only concerned with correlation percentages. Because we measure 45 degrees offset, we maximally destroy the entanglement and our correlation percentage falls to 50% (coincidences between Alice and Bob). There is no EPR entanglement and no violation of Bell inequalities.

As I understand the strand model, this makes perfect sense. At the time the black box is encountered, the measurement of the helicity via the PBS in the black box causes the normal collapse and the photons are no longer entangled. Because I know which path the photon took to get to Alice, the results of Alice and Bob's measurements are no longer entangled.

iii) Same as case ii) above except: I don't bother to detect which path the photon went through before I send it on to Alice. In fact, I make sure that the 2 paths coming out of the Black Box PBS are exactly equal (but suitably phase matched so the path taken is no longer knowable) but they go in different directions before I finally route them out of the Black Box and on to Alice. In other words, knowledge of the path taken inside the black box PBS is quantum erased. (Of course this is an ideal world, in practice not so easy.)

In such case, I believe Alice and Bob will see full entanglement just as in case i). The correlation will be 100% as before in case i).

As I understand the strand model, the act of having the basis state measured by the PBS in the black box ends the entanglement. There is no further connection between the 2 photons eventually seen by Alice and Bob. So my question is: how does putting Alice's "2 halves back together again" change Bob so that Bob is once again entangled with Alice? Seems to me that Bob is now happily on his merry way. Obviously, you would in practice perform a Bell test to see if the Inequality is violated while also checking to see that perfect EPR correlations are seen.

I don't see how the strand model would yield the correct expected results. How could the Alice and Bob strands get hooked up again? Seems like something would need to move along both paths (half entangled tangles?) so they could merge together later - but that makes no sense to me. Any comments? If my example is not clear, I can put together a diagram to help.

 

[SimonA]

Christoph

Do you really believe that you have a rational explanation for youngs slit experiment and entanglement? I like your strand idea, but I don't see how it is different from considering 3d space as one superdimension, time as another, and "strands" as a label for the others (beign categorically the same).

You like to simplify and use "strand" as a placeholder. Can you see how that prevents us from having explanatory clarity?

If you're not interested in explaining, then why not just accept Bohr and his Copenhagen explanation?

 

[SimonA]

Otherwise please explain youngs slit experiment(refined to a single particle interfering with itself),and entanglement such that a waitress could understand them.

When the wave function collapses, how is that transmitted through space ? What makes "strands" so stable as packets of energy when they merge and break? What is the difference between electrons and photons on the one hand, and neutrons and protons on the other?

 

[rewebster]

This is an issue of classical electrodynamics, not of unification! Magnetic poles are consequences of the lack of magnetic monopoles, and of the motion of electric charges. Magnets have two poles because the charges inside them move and spin. Any model that contains electric charges that follow Coulomb's law thus explains the two poles of a magnet.

"Magnetism is relativistic electricity." One place where to read about this, in particular about how magnetism appears from Coulomb's law, is the third volume of my Motion Mountain physics text, found at www.motionmountain.net. But almost all textbooks on electrodynamics tell how magnetic poles appear.

That may simply explain the classically accepted reason why a magnet has two poles, but the question was why there is a duality at each pole; and,

"Magnetic poles are consequences of the lack of magnetic monopoles" is sort of like saying the reason gravity is the way it is, is from a lack of anti-gravity.

 

[physics8553]

(1) Do you really believe that you have a rational explanation for youngs slit experiment and entanglement?

(2) I like your strand idea, but I don't see how it is different from considering 3d space as one superdimension, time as another, and "strands" as a label for the others (beign categorically the same).

(3) You like to simplify and use "strand" as a placeholder. Can you see how that prevents us from having explanatory clarity?

(4) If you're not interested in explaining, then why not just accept Bohr and his Copenhagen explanation?

(1) Yes, the strand model explains interference. The strand model provides a visualization of wave functions, and explains interference in the same way as wave functions explain it: as a result of wave function addition.

(2) "superdimension" is a term with no content to me (and most others),

(3) "strands" are not place holders. In the model, strands are the basic fabric of reality. The define space, curvature and wave functions; these result through the blurring of crossings. It is simple and clear.

(4) Decoherence is not in contrast with the "Copenhagen" interpretation; decoherence explains the collapse as a process governed by the same evolution equation as normal quantum evolution. The strand model confirms decoherence.

 

[physics8553]

(1) Otherwise please explain youngs slit experiment(refined to a single particle interfering with itself),and entanglement such that a waitress could understand them.

(2) When the wave function collapses, how is that transmitted through space ? What makes "strands" so stable as packets of energy when they merge and break? What is the difference between electrons and photons on the one hand, and neutrons and protons on the other?

(1) What is hard about interference? It is the result of wave function addition. The addition of wave functions is defined in the strand model. It then turns out that destructive interference appears in situations where addition cannot be performed for topological reasons.

Entanglement is defined in many details in the 6th volume. I think that a waitress can understand it: entanglement of many-particle systems is modeled as entangled tails of the various particle tangles involved.

(2) Collapse happens as always: it is a change of the wave function for which group velocity is ill-defined.

Electrons are made of 3 strands, photons of one strand, nucleons are made of three quarks that consist of two strands each. There are tangle structures for all these particles in the 6th volume, in chapter 12 of www.motionmountain.net/research[/URL].

 

[physics8553]

iii) Same as case ii) above except: I don't bother to detect which path the photon went through before I send it on to Alice. In fact, I make sure that the 2 paths coming out of the Black Box PBS are exactly equal (but suitably phase matched so the path taken is no longer knowable) but they go in different directions before I finally route them out of the Black Box and on to Alice. In other words, knowledge of the path taken inside the black box PBS is quantum erased. (Of course this is an ideal world, in practice not so easy.)

In such case, I believe Alice and Bob will see full entanglement just as in case i). The correlation will be 100% as before in case i).

As I understand the strand model, the act of having the basis state measured by the PBS in the black box ends the entanglement. There is no further connection between the 2 photons eventually seen by Alice and Bob. So my question is: how does putting Alice's "2 halves back together again" change Bob so that Bob is once again entangled with Alice? Seems to me that Bob is now happily on his merry way. Obviously, you would in practice perform a Bell test to see if the Inequality is violated while also checking to see that perfect EPR correlations are seen.

I don't see how the strand model would yield the correct expected results. How could the Alice and Bob strands get hooked up again? Seems like something would need to move along both paths (half entangled tangles?) so they could merge together later - but that makes no sense to me. Any comments? If my example is not clear, I can put together a diagram to help.

Hm, if I understand your case III correctly, the PBS has no effect at all.

Generally speaking, the strand model just visualizes quantum theory; there are no differences at all. So I have two questions to understand what you say: (1) did I understand case iii correctly?
And (2) why do you suspect that in this case the strand model should give something else than usual quantum mechanics?

 

[physics8553]

(1) That may simply explain the classically accepted reason why a magnet has two poles, but the question was why there is a duality at each pole; and,

(2) "Magnetic poles are consequences of the lack of magnetic monopoles" is sort of like saying the reason gravity is the way it is, is from a lack of anti-gravity.

(1) The strand model just confirms the "classically accepted reason", because that is the only reason :-)

In nature, there is no "duality at each pole".

(2) No. My statement was and is: "Magnetic poles are consequences of the lack of magnetic monopoles, and of the motion of electric charges." Every high-school book on electricity and magnetism explains the details.

 

[rewebster]

"In nature, there is no "duality at each pole"."

hmmmm...

I don't think high school texts explain magnetism as a lack of mono-poles.

 

[DrChinese]

Hm, if I understand your case III correctly, the PBS has no effect at all.

Generally speaking, the strand model just visualizes quantum theory; there are no differences at all. So I have two questions to understand what you say: (1) did I understand case iii correctly?
And (2) why do you suspect that in this case the strand model should give something else than usual quantum mechanics?

I understand that the strand model should yield results as usual quantum mechanics. In fact, that is what is designed to do. However, the strand model - precisely because it is a visual model - seems to imply a different meaning for probability amplitudes.

So in my case iii), we make a measurement (by running the photon through the PBS) and that should cause collapse according to the mechanism you describe. I say that it is possible to erase the effect of that measurement by recombining the PBS output streams (again, easier said than done). On the other hand, Bob collapsed into a definite state when Alice went through the PBS. How will Bob know that the original entanglement is to continue IF the 2 streams are later recombined (i.e. which path information is erased) but not to continue the entanglement otherwise?

So I guess the question comes back to the traditional dilemma of "what is a measurement". Is the measurement when the photon passes through the PBS? Or is the measurement occurring when it is possible to deduce the results? Because as fuzzy as the second option is, it seems to conflict with any visual representation.

 

[physics8553]

(1)I understand that the strand model should yield results as usual quantum mechanics. In fact, that is what is designed to do. However, the strand model - precisely because it is a visual model - seems to imply a different meaning for probability amplitudes.

(2) So in my case iii), we make a measurement (by running the photon through the PBS) and that should cause collapse according to the mechanism you describe. I say that it is possible to erase the effect of that measurement by recombining the PBS output streams (again, easier said than done). On the other hand, Bob collapsed into a definite state when Alice went through the PBS. How will Bob know that the original entanglement is to continue IF the 2 streams are later recombined (i.e. which path information is erased) but not to continue the entanglement otherwise?

(3) So I guess the question comes back to the traditional dilemma of "what is a measurement". Is the measurement when the photon passes through the PBS? Or is the measurement occurring when it is possible to deduce the results? Because as fuzzy as the second option is, it seems to conflict with any visual representation.

(1) Why different? Probability amplitudes are "blurred" strand crossings, and behave in the same way.

(2+3) I still do not know what you mean in your case III: either you measure or you do not. A measurement is an interaction with a bath, thus an irreversible interaction, that is designed for some observable.

If you interact with a bath, there is no way to "undo" the measurement by recombining states after the measurement. If you do NOT interact with a bath, then it is nota measurement. I simpy do not get what you mean.

To test whether the strand model agrees or contradicts quantum mechanics, we can take a clearly defined situation in quantum mechanics, and then check whether the strand model reproduces it or nor. In this case, such a test is impossible so far, for me, because the situation you describe is unclear to me.

On the other hand, I describe in chapter 9 "Quantum theory of matter deduced from strands" (http://www.motionmountain.net/research/index.html ) how the strand model reproduces Hilbert spaces, wave functions, interference, Schroedinger's equation, and Dirac's equation. And the idea is simply that wave functions are time-averaged strand crossings. So the strand model can be checked by everybody: the visualization of wave functions is simple, direct and can be learned by anybody in a few minutes.

But I agree that the idea that wave functions are blurred crossings of strand tangles needs to be checked in all directions. After all, it is at the basis of the deduction of the three gauge interactions as consequences of the three Reidemeister moves (the title of this thread) and also at the basis of the statement that there are only three generations of quarks and leptons.

 

[physics8553]

"In nature, there is no "duality at each pole"."

hmmmm...

I don't think high school texts explain magnetism as a lack of mono-poles.

Again: my statement was and is: "Magnetic poles are consequences of the lack of magnetic monopoles, and of the motion of electric charges."

The first half is one of Maxwell's equations, the second half is a combination of the other three Maxwell equations (and the Lorentz force). I really suggest that you look up your high school book on classical electromagnetism. It does contain the explanation of why there are always two poles. Magnetic fields can only be created by moving electric charges (in the absence of magnetic monopoles) and such fields automatically have two poles.

Unfortunately, I cannot explain things much more if you insist on misquoting me! But I can assure you that most high school books are fun to read if one does so for pastime or for curiosity, and if one does not *need* to read them.

 

[rewebster]

Maybe you're trying to explain what magnetism is, and as it has a relationship to the electric charge.

What I was looking for from you is, if you're saying the theory is a TOE, I thought you may have the explanation of how and why each of a magnet's poles is capable of both attraction and repulsion--the mechanism of the process.

Just stating that its similar the electric charge or the explanation in your post #28 ("it results from the chirality of the matter tangles"), relies on, when a person read it, they say to themselves, "OH, magnetism is when matter tangles!"

 

[physics8553]

Maybe you're trying to explain what magnetism is, and as it has a relationship to the electric charge.

What I was looking for from you is, if you're saying the theory is a TOE, I thought you may have the explanation of how and why each of a magnet's poles is capable of both attraction and repulsion--the mechanism of the process.

Just stating that its similar the electric charge or the explanation in your post #28 ("it results from the chirality of the matter tangles"), relies on, when a person read it, they say to themselves, "OH, magnetism is when matter tangles!"

Since magnetic fields are due to moving charges, the possibility of north and south poles to attract or repel is due to the repulsion and attraction of unlike and like charges. This relation of magnetism to electrostatics is part of classical electrodynamics and explained in any schoolbook. (Really!)

So the only thing to understand is how charges attract or repel. This happens via exchange of virtual photons. This is part of quantum electrodynamics (QED).

One can then ask how virtual photon exchange happens. Only at this stage do strands enter. This is explained in the strand model: photons are helical single strands. Note that it is wrong to say that "magnetism is when matter tangles". Magnetism is a field. Instead, magnetism is when electric charges move. Following QED, electric charges continuously exchange virtual photons. The same happens in the strand model: photons a single helical strands, randomly exchanged between charges; charges are chiral tangles. That is all of electrodynamics in two statements. In particular, Maxwell's equations follow from the two statements, and all answers to the issues you raised.

 

[heinz]

Christoph, in your strand model you propose tangles for the gauge bosons, for the quarks and for the leptons. When you present the quark tangles, you explain that they are rational tangles of 2 strands, and as such the tangles explain why quarks do not appear as free particles. Then you present the lepton tangles, which are made of 3 strands. But the lepton tangles you give are "almost rational" as well; so they should also not appear as free particles!? Can you explain more clearly why, in your strand model, leptons are observed as free particles, but not quarks?

 

[heinz]

I looked through the literature and did not find anything on the matter. I found some ideas on polymers and evolution equations similar to the Schrödinger equation, but nothing of the type you ask for. Of the people that tried to model wave functions, nobody seems to have though about strands and tangles - except of course, Battey-Pratt and Racey in 1980. But their ideas did not catch on. Racey wrote to me saying that they tried to ask Dirac about this, but Dirac never answered. What a pity!

Do you have something specific in mind?

Christoph, I had nothing particular in mind. I simply find it hard to believe that of the thousands of people working on quantum theory, nobody has looked at fluctuating strands. I looked through arxiv, but did not find anything. There are many papers on the "polymer representation" of quantum theory, but they have nothing to do with your approach.

 

[DrChinese]

(2+3) I still do not know what you mean in your case III: either you measure or you do not. A measurement is an interaction with a bath, thus an irreversible interaction, that is designed for some observable.

If you interact with a bath, there is no way to "undo" the measurement by recombining states after the measurement. If you do NOT interact with a bath, then it is nota measurement. I simpy do not get what you mean.

To test whether the strand model agrees or contradicts quantum mechanics, we can take a clearly defined situation in quantum mechanics, and then check whether the strand model reproduces it or nor. In this case, such a test is impossible so far, for me, because the situation you describe is unclear to me.

I don't want to pull the thread away from the main discussion, and I am not trying to introduce anything novel. Just trying to understand a bit more about the strand model and entanglement... and there is probably nothing more to understand, but I wanted to check anyway.

In any quantum eraser, a "measurement" appears to be made but then the results of the "measurement" are erased such that it is not possible, in principle, to know the results. I put measurement in quotes because some would say that this does not qualify as a true measurement. This avoids confronting the issue of what is a measurement by simply saying that if the indicated quantum effect was restored (due to erasure) then no measurement occurred.

I attached a diagram imagining an eraser acting on Alice, entangled with Bob. This is taken from page 9 of the following: http://www.wheaton.edu/physics/faculty/faries/double.PDF

In normal QM, we say that there was no measurement if the results of the splitting of the incident beam are erased properly. I was wondering if the strand model says the same thing. I would guess your answer will be YES.

But for that to be the case, I would imagine that there is something "blurred" going one way and something else "blurred" going the other. So that each path has 50% of something, which I would call a probability amplitude. So I am trying to visualize that using your model. Obviously, Bob is still entangled with Alice IF Alice is put back together again. But Bob is not entangled with Alice any more if we block either half of the PBS split beams - even if the Alice photon did not traverse that blocked path. Again, not trying to probe the pros and cons of counterfactual reasoning or anything like that, just wondering if your model provides any insight into what happens with quantum erasers and measurements.

 

[JustinLevy]

Why is there still discussion on this 'theory'?
It appears to be pure crackpottery, or at best something that should only go in the independent research forum.

In true layman form the 'theory' is never specified well enough to really even do anything. Statements are made without justification or logical deduction almost like a game of 'word association' to get from one statement to another and then label that a 'derivation'. Sometimes contact is made to other people's work in an attempt to 'subsume' their results (for example referencing Jabobson's thermo->GR paper).

This is not a theory. The hand wavy discussions aren't even self consistent. He claims to reproduce SR and GR naturally, but then claims there are limits to momentum and that horizons are observer dependent. These statements wildly disagree.

Either SR is reproduced or it isn't. Either GR is reproduced or it isn't.

Furthermore, the very STARTING point of this 'theory' is not self-consistent. The starting point is that everything is strands (both particles and space), and that only changes in crossings are observable ... yet:

No, strands can never interpenetrate or pass each other. In other words, crossings can switch only by one strand *rotating* around the other. Passing through is never allowed.

As already pointed out by another poster, this means what he is calling "crossings" have no topological meaning. Check out these 'crossing changes' to make this even more clear (his attached figure here):
https://www.physicsforums.com/showpost.php?p=2235208&postcount=41

Even if an embedding is given in 3-D space, it is still unclear how one would even define a crossing in the manner suggested there, as it seems to require both a series of folliations into 2-D space so that a projection can be made as well as an externally defined preferred orientation so that a 'twist' can be considered a 'change' despite the same strand segment still being above the other.

All this external requirement is lumped into an 'observer'. So the observer is outside the theory itself. The strands must be described in this space and time externally imposed (an "observer") to even make sense, and therefore the strands cannot explain space and time.It is not self-consistent.
It does not provide enough details to even be mathematically specified so that others may check 'derivations'.
It disagrees with SR (imposing a momentum limit).
It disagrees with GR (causality horizons are observer dependent).

How can this 'theory' not be dismissed immediately?

 

[physics8553]

(1) Why is there still discussion on this 'theory'?

(2) In true layman form the 'theory' is never specified well enough to really even do anything. Statements are made without justification or logical deduction almost like a game of 'word association' to get from one statement to another and then label that a 'derivation'. Sometimes contact is made to other people's work in an attempt to 'subsume' their results (for example referencing Jabobson's thermo->GR paper).

(3) This is not a theory. The hand wavy discussions aren't even self consistent. He claims to reproduce SR and GR naturally, but then claims there are limits to momentum and that horizons are observer dependent. These statements wildly disagree.

(4) As already pointed out by another poster, this means what he is calling "crossings" have no topological meaning. Check out these 'crossing changes' to make this even more clear (his attached figure here):
https://www.physicsforums.com/showpost.php?p=2235208&postcount=41

(5)All this external requirement is lumped into an 'observer'. So the observer is outside the theory itself. The strands must be described in this space and time externally imposed (an "observer") to even make sense, and therefore the strands cannot explain space and time.

(6) It does not provide enough details to even be mathematically specified so that others may check 'derivations'.

(7) It disagrees with SR (imposing a momentum limit).

(8) It disagrees with GR (causality horizons are observer dependent).

(1) My guess: the strand model is still discussed because it is one of the few approached that explains the three gauge interactions. It maybe even is the only one so far.

(2) There is a basic postulate ("crossing switches define the Planck units"), and all the rest, including predictions on particle content, gauge groups, Planck energy behaviour, is deduced from it.

(3) That energy and momentum of elementary particles is limited by the Planck values is part of any attempt for a unified description. It does not contradict special relativity nor general relativity at any experimentally accessible energy.

(4) Crossings are defined as the locations with the smallest distance between two strand segments, That is a perfectly clear definition. The drawings you link to show examples of this definition.

(5) Strands indeed move in a background (exterior) space. But they also create physical space. This can be made consistent.

(6) The strand model provides a derivation of a maximum speed (and thus of special relativity), a maximum power (and thus general relativity) an a minimum action (and thus quantum theory). The derivations is given in detail in http://www.motionmountain.net/research/index.html . The derivations can be checked by anybody. The derivations of the evolution equations are given in full detail, and each step is open for checking.

(7) See point 3. Anybody is free to believe that there is no momentum or energy limit for elementary particles, but there is no evidence for this; in contrast, there is a lot of evidence for the existence of Planck limits on energy and momentum for elementary particles.

(8) In general relativity, horizons are observer dependent, as shown by any black hole: it has a horizon for observers at infinity, but not one for an infalling observer. Maybe you wanted to say something else?

 

[physics8553]

In normal QM, we say that there was no measurement if the results of the splitting of the incident beam are erased properly. I was wondering if the strand model says the same thing.

(1) I would guess your answer will be YES.

(2) But for that to be the case, I would imagine that there is something "blurred" going one way and something else "blurred" going the other. So that each path has 50% of something, which I would call a probability amplitude.

(3) So I am trying to visualize that using your model. Obviously, Bob is still entangled with Alice IF Alice is put back together again. But Bob is not entangled with Alice any more if we block either half of the PBS split beams - even if the Alice photon did not traverse that blocked path.

(4) Again, not trying to probe the pros and cons of counterfactual reasoning or anything like that, just wondering if your model provides any insight into what happens with quantum erasers and measurements.

My answer to (1) and (2) would be yes.

(3) I would say yes, because no baths are involved.

(4) I am not an an expert on quantum erasers. But visualizing tangles and visualizing wave functions is essentially the same. The two visualizations do not differ from each other much. A tangle is sort of a short-time snapshot of a wave function. Does this help a little?