Ballentine's Ensemble Interpretation Of QM

[kye]

This is simply wrong. QC relies solely on the math, not on its interpretation. The math is interpreted as a "real" superposition in standard qm, but there is no need to do that for QC to work. All Bohmian mechanics does is dividing the physics into something considered a real particle and a guiding wave. Shifting the math part which leads to superposition in standard QM to the guiding wave does not change a single prediction - even without superposition.

It is stated that quantum computing can create quantum computers that can hack encryptions that can take convensionally thousands of years. Since QC relies solely on the math and even if there is no simultaneous superposition, how can you create classical algorithms or connections that can create quantum computer and hack encryptions in seconds that will year 100 years?

 

[Ken G]

Yes, the math is the key. Indeed I think there is a lot of confusion about what an interpretation of a mathematical theory really should be in the first place. In mathematics, interpretations are created for only one reason-- to help understand the mathematical structure in question. There is no sense to which one interpretation or the other is "what is really happening" in that mathematical structure, because nothing is really happening in that mathematical structure, it's just a mathematical structure. But in physics, we have an issue about what an interpretation is because we have both-- we have formal mathematical structures which allow us to prove things and derive ramifications, and we have a sense that "something is really happening." So we want an interpretation to be both things, and it just isn't. We must pick which we want it to be-- do we have a formal mathematical structure that we want to understand, which can be approached via any valid interpretation (even ones that sound wildly different from each other), or do we have a description of what is really happening, in which case we really have no right to assume it will function like a formal mathematical system in the first place. You just can't have it both ways, it's too much to ask from any interpretation. The solid ground, therefore, is to stick to the formal mathematical meaning of an interpretation, and not think of it as a description of what is actually happening. I should think we would have learned to be suspicious of the latter by now anyway.

 

[kye]

Yes, the math is the key. Indeed I think there is a lot of confusion about what an interpretation of a mathematical theory really should be in the first place. In mathematics, interpretations are created for only one reason-- to help understand the mathematical structure in question. There is no sense to which one interpretation or the other is "what is really happening" in that mathematical structure, because nothing is really happening in that mathematical structure, it's just a mathematical structure. But in physics, we have an issue about what an interpretation is because we have both-- we have formal mathematical structures which allow us to prove things and derive ramifications, and we have a sense that "something is really happening." So we want an interpretation to be both things, and it just isn't. We must pick which we want it to be-- do we have a formal mathematical structure that we want to understand, which can be approached via any valid interpretation (even ones that sound wildly different from each other), or do we have a description of what is really happening, in which case we really have no right to assume it will function like a formal mathematical system in the first place. You just can't have it both ways, it's too much to ask from any interpretation. The solid ground, therefore, is to stick to the formal mathematical meaning of an interpretation, and not think of it as a description of what is actually happening. I should think we would have learned to be suspicious of the latter by now anyway.

We were misled before. In the past we thought atoms can't exist and don't exist because the maths of Newtonian mechanics is enough. Now we can detect the pions. This is the reason many want a deeper understanding for a possible non-local hidden variables and we can't blame them for it.

In the pop-sci books. We are exposed to the concept that before measurements, the physical world or the properties don't actually exist and there is literal superposition of the objects, and our observation collapse the wave function. My question is, there is no way to refute this aint it. Those who understand the math want to just stick with the math because of experience with the electron spin not rotating in real world. The pop-sci books kinda want to (in analogy to quantum) show the public the electron spin is literally revolving twice in one revolution. Is my impression of the situation correct?

 

[bohm2]

The solid ground, therefore, is to stick to the formal mathematical meaning of an interpretation, and not think of it as a description of what is actually happening. I should think we would have learned to be suspicious of the latter by now anyway.

I don't understand this part. What is a formal mathematical meaning of an interpretation? Maybe I'm misunderstanding your point but as I see it, Fuchs, of all people, wrote a good paragraph worth regurgitating:

To take a stand against the milieu, Asher had the idea that we should title our article, “Quantum Theory Needs No ‘Interpretation’.” The point we wanted to make was that the structure of quantum theory pretty much carries its interpretation on its shirtsleeve—there is no choice really, at least not in broad outline. The title was a bit of a play on something Rudolf Peierls once said, and which Asher liked very much: “The Copenhagen interpretation is quantum mechanics!” Did that article create some controversy! Asher, in his mischievousness, certainly understood that few would read past the title, yet most would become incensed with what we said nonetheless. And I, in my naivet´e, was surprised at how many times I had to explain, “Of course, the whole article is about an interpretation! Our interpretation!”...The question is completely backward. It acts as if there is this thing called quantum mechanics, displayed and available for everyone to see as they walk by it—kind of like a lump of something on a sidewalk.

The job of interpretation is to find the right spray to cover up any offending smells. The usual game of interpretation is that an interpretation is always something you add to the preexisting, universally recognized quantum theory. What has been lost sight of is that physics as a subject of thought is a dynamic interplay between storytelling and equation writing. Neither one stands alone, not even at the end of the day. But which has the more fatherly role? If you ask me, it’s the storytelling. Bryce DeWitt once said, “We use mathematics in physics so that we won’t have to think.” In those cases when we need to think, we have to go back to the plot of the story and ask whether each proposed twist and turn really fits into it. An interpretation is powerful if it gives guidance, and I would say the very best interpretation is the one whose story is so powerful it gives rise to the mathematical formalism itself (the part where nonthinking can take over). The “interpretation” should come first; the mathematics (i.e., the pre-existing, universally recognized thing everyone thought they were talking about before an interpretation) should be secondary.

Interview with a Quantum Bayesian
http://arxiv.org/pdf/1207.2141v1.pdf

 

[strangerep]

Electron spin acts in abstract space.. because two revolutions made one turn. It has no correlate to physical world.

Nonsense. There are physical experiments you can perform in your own home that show how a rotation by $2\pi$ isn't necessarily equivalent to no rotation at all, but rotation by $4\pi$ is.

Look up "Dirac Scissors" (also known as the "belt trick" and several other names).
http://en.wikipedia.org/wiki/Plate_trick
Here's some animations referenced there:
http://vimeo.com/62228139
http://vimeo.com/62143283
This stuff serves to prove that one's natural understanding of physical 3-space, acquired in early childhood, is naive and even mistaken, in some ways.

There are also experiments involving electron interferometry where one side of the interferometer has a magnetic field which rotates the electrons on that side through $2\pi$, with the result that they cancel when the two sides are brought back together.

I wonder what Ballentine says about the higgs.

Maybe you should actually study some non-popsci books instead of making the endless crackpot suggestions that you've sprinkled like pepper throughout this thread.

 

[bhobba]

My question is, there is no way to refute this aint it.

There isn't. The junk you read in the popular press may be true. That's not the point, or why it generally makes me want to run away screaming - the point is they say it as if its the only view. A much more rational view exists - for example bog standard CI is much more rational than this observer created tripe - but they don't say it - because its not 'sensationalist' enough.

When was the last time you saw any populist book say Copenhagen assumes a world out there entirely common-sensical, trees make sounds when there is no observer, and all our every day intuition holds true? That's not going to sell is it - so they don't say it. But that is precisely what Copenhagen, and the Ensemble interpretation this thread is about says.

The key issue is how such a world emerges from a theory that only makes predictions about observations that appear in such a world. That is a very deep issue and the true quantum mystery. A lot of progress has been made - but issues still remain and more research is required before a satisfactory explanation is found. I suspect a few revolutions will occur along the way - indeed we may be in the middle of one right now - I find the following very thought provoking:
https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics/

Thanks
Bill

 

[Cthugha]

It is stated that quantum computing can create quantum computers that can hack encryptions that can take convensionally thousands of years.

Yes, at least this is what we tell the funding agencies. In real life, scaling is a problem. Few qubits are ok and we can work with them. Many are really complicated. We will see how far we can get. Rainer Blatt seems to be doing pretty well.

Since QC relies solely on the math and even if there is no simultaneous superposition, how can you create classical algorithms or connections that can create quantum computer and hack encryptions in seconds that will year 100 years?

Classical algorithms do not work. You will need quantum algorithms like Shor's algorithm and qubit states. These are superpositions from the math point of view. However, simply speaking "superposition" vs. "mixture" is just a code for "when you have two indistinguishable possible states, do the sum and take the expectation value, otherwise get the expectation values first and find their sum". Having this mathematical structure does not necessarily mean that both states are simultaneously real (like the famous "the particle is in two positions at once"). It may well be, but it does not have to. QM is a statistical theory. It does not tell us anything about what is "really" happening in a single experimental run.

 

[Nick666]

I find the following very thought provoking:
https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics/

There's something I don't understand in that article, down the page, starting at "Recently, a strange duality has been found between string theory and quantum field theory" and ending with the paragraph.

Is he referring to the duality as the discovery ? And then is he suggesting the illusion of dimensions and space-time as an answer to the cause of that duality ?

 

[Maui]

These are superpositions from the math point of view. However, simply speaking "superposition" vs. "mixture" is just a code for "when you have two indistinguishable possible states, do the sum and take the expectation value, otherwise get the expectation values first and find their sum". Having this mathematical structure does not necessarily mean that both states are simultaneously real (like the famous "the particle is in two positions at once"). It may well be, but it does not have to. QM is a statistical theory. It does not tell us anything about what is "really" happening in a single experimental run.

This makes little sense to me and seems to be another conspiracy theory. Quantum computers are real world macroscopic devices, not ideas based on math. Nobody has seen the Sun directly or visited it, but all data suggests that there is a Sun. But maybe it's not there. Perhaps it may well be, but it does not have to. QM is a statistical theory after all. Is that a sensible statement?

 

[Maui]

This criticism was already addressed in a previous thread and some links provided:

Quantum computation from a de Broglie-Bohm perspective
http://xxx.lanl.gov/pdf/1205.2563v1.pdf

Quantum Computing in the de Broglie-Bohm Pilot-Wave Picture
http://xxx.lanl.gov/pdf/1012.4843v1.pdf

And also addressed on Physics Stack Exchange: Does quantum computing rely on particular interpretations of quantum mechanics?
http://physics.stackexchange.com/qu...rticular-interpretations-of-quantum-mechanics

Personally, I find the arguments presented by those who propose that quantum theory itself is emergent from a deeper, more exact theory on a sub-quantum level as the most reasonable view, but we're not there yet, so I guess we're kind of debating which is the best means to achieve that goal (if achievable). Maybe it doesn't matter as Ken G argues. Maybe it does. But interpretations/foundations may shed light or spawn other areas of research that may shed light as pointed out by people like Lucien Hardy, Spekkens, Leifer, etc.

Those experimental results are further evidence against local theories not dBB.

You have referenced a few hundred papers just this year alone and not everyone has sufficient time to read them all in every thread. I was hoping for an explanation from your point of view how the non-local guiding wave is compatible with the superpositions of states the said guiding wave was supposed to do away with(for a somewhat classical and intuitive picture of the world). Superpositions were and are troublesome for the idea of macro realism, Bohm's idea was to restore objectivity by removing superpositions of states. He was wrong.

BTW, it's not allowed to link to blogs here. I took a look at the answers and none addressed the issue I raised above. If nobody can answer this, they are wrong and would rather believe in a conspiracy(the pilot wave has a new function - it has to perform complex conspiratorial acts to suit someone's agenda).

 

[Maui]

It feels like a superposition of states. Oh wait, we are back to standard quantum mechanics.

Yes, of course, that's why it is called an interpretation of standard quantum mechanics.

You don't understand. Bohmian mechanics makes statements about what was until recently thought to be unobserveable quantum behavior. It's observed now, it's been a decade. It's a new development and the guiding wave is in trouble with experiments. On the other hand, quantum mechanics has no problems with superpositions and quantum weirdness.

 

[bhobba]

not ideas based on math.

And neither is a weight attached to a spring.

Funny though - its behavior is well described by math.

What a mathematical model is, is very very basic to physics. But for some reason a few people get confused. I am suspicious its because they haven't actually been in a mathematical modelling, differential equation, computational modelling, or similar class where one of the activities is to check exactly how well these models describe the actual system behavior. Its very interesting taking an actual model, continually refining it and seeing exactly how well it describes a situation. If you have then its very obvious what's going on and its very simple. Once you see just how well it does work, one tends to think of the math as what's going on - its of course just a description - but works so well you tend to not think about that explicitly.

People like that are NOT saying the math is the reality - just it describes it so well you tend to think of it that way. But without doubt virtually all trained physicists, or people trained in applied math like I was, view it like that.

Thanks
Bill

 

[Cthugha]

This makes little sense to me and seems to be another conspiracy theory. Quantum computers are real world macroscopic devices, not ideas based on math.

Mathematical models are fundamental to physics. Englert's essay I linked earlier represents the foundations of physics well: formalism (the mathematical model), phenomena (experimental results) and interpretation (the link between both). And this interpretation is a minimal one: there is a wavefunction and it tells us what is happening on average for a large number of trials. Any "deeper" interpretation already makes assumptions and moves away from physics and onward into the realm of philosophy. They are not needed for actually doing experiments. Assuming that the mathematical formulation of superposition means that "particles are actually in two places at once" is such an unnecessary assumption. It does not help with the math. It does not change any predictions. It is therefore not really physics.

Nobody has seen the Sun directly or visited it, but all data suggests that there is a Sun. But maybe it's not there. Perhaps it may well be, but it does not have to. QM is a statistical theory after all. Is that a sensible statement?

I do not see the connection. The sun is considered a black body with some temperature and every single experiment will give you the same result: it will be in line with a black body at some temperature (ignoring of course atmospheric effects and other small deviations) out there in the sky. You can map the experimental results to the mathematical model directly. However, if you have any other interpretation which uses the same math and explains the same observations and is also in agreement with all the other experiments, it would of course also be valid. I am just not aware of any.

For superpositions, you can also directly map the experimental results to the mathematical model: You do a lot of measurements and the probability distribution in the ensemble average behaves as the mathematical model predicts. You cannot do so for a single measurement as qm is a statistical model and does not predict much for a single measurement. Accordingly, qm also simply does not predict that you get a particle in two places for a single experimental run. QM does not tell us anything about how to interpret superpositions for a single experiment. Claiming something else is pop-sci mumbo jumbo.

You don't understand. Bohmian mechanics makes statements about what was until recently thought to be unobserveable quantum behavior. It's observed now, it's been a decade. It's a new development and the guiding wave is in trouble with experiments.

This is of course wrong. Bohmian mechanics is not at odds with any experimental results. What people observe in experiments is that results follow the mathematical model of superposition even for quite large objects like nanomechanical cantilevers. This is pretty cool, but it is not at odds with Bohmian mechanics. Bohmian mechanics has the same math and comes to the same results in the ensemble average. You would need to create an experiment going beyond qm to rule out this interpretation. That means that you would really need to do an experiment that measures a superposition state as the result of a single experimental detection and not by backtracking from many measurements. However, nobody knows how to do that.

On the other hand, quantum mechanics has no problems with superpositions and quantum weirdness.

No, it does not because it does not care about it. Standard qm tells us way less than people often think. Standard qm does not even have collapse. It has state reduction. Interpreting that as collapse is already an unnecessary assumption. In my opinion discussing interpretations has become popular among laymen, while working physicists rather discuss physics and do not care about interpretations at all, especially in experimental physics. Most working physicists I know are already quite annoyed when another bad pop-sci summary about some nature or science article comes out claiming things being in several places at once, backward causation or fancy non-locality effect because the stuff in the pop sci summary is never claimed in the article itself and one can be sure that friends, relatives and that unknown guy on the bus who somehow heard that you do quantum physics for a living will ask you about how that works and one needs to spend a lot of time in order to undo all the damage already done by those pop-sci summaries which just try to make things sound sensational.

I recently met a guy working on nanomechanics and they got a mechanical resonator close to the ground state already a few years ago. Some journalist came over and asked him what that might be good for and he answered that the resonance frequency might change if some atoms or molecules settle on the oscillator, so one might identify some elements as a long term goal. The headline of the final article was: Scientists develop artificial nose...

 

[bhobba]

Standard qm tells us way less than people often think. Standard qm does not even have collapse. It has state reduction. Interpreting that as collapse is already an unnecessary assumption.

Ahhh. Too true. Too true.

Thanks
Bill

 

[atyy]

How does the ensemble interpretation work in cosmology? What are the multiple preparations in observing the anisotropy of the microwave background?

 

[Maui]

For superpositions, you can also directly map the experimental results to the mathematical model: You do a lot of measurements and the probability distribution in the ensemble average behaves as the mathematical model predicts. You cannot do so for a single measurement as qm is a statistical model and does not predict much for a single measurement. Accordingly, qm also simply does not predict that you get a particle in two places for a single experimental run. QM does not tell us anything about how to interpret superpositions for a single experiment. Claiming something else is pop-sci mumbo jumbo.

Experiment says so, you live in the 1940's. Small scale prototypes of quantum computers have already been implemented and I posted links earlier in the thread.

This is of course wrong. Bohmian mechanics is not at odds with any experimental results. What people observe in experiments is that results follow the mathematical model of superposition even for quite large objects like nanomechanical cantilevers. This is pretty cool, but it is not at odds with Bohmian mechanics. Bohmian mechanics has the same math and comes to the same results in the ensemble average.

That'd be all good if superpositions were not experimentally confirmed. You are completely wrong, that's why you turn this into what the maths of the BI says(it's the math that needs interpretation!). It's an interpretation, it's supposed to explain classical behavior and it does so using a pilot wave. No wonder you don't mention it anywhere.

You would need to create an experiment going beyond qm to rule out this interpretation. That means that you would really need to do an experiment that measures a superposition state as the result of a single experimental detection and not by backtracking from many measurements. However, nobody knows how to do that.

That's the same as asking for direct contact(touch) with the Sun to believe that it exists. And you know what you require is not possible but it's a shelter, when you have no other way out.

On the other hand, quantum mechanics has no problems with superpositions and quantum weirdness.

No, it does not because it does not care about it. Standard qm tells us way less than people often think.

What are you talking about? We are discussing superpositions of states and you are misinforming people that qm doesn't care about it. That's the ABC of qm, so what are you talking about?

Standard qm does not even have collapse. It has state reduction. Interpreting that as collapse is already an unnecessary assumption.

How did it get to discussing collapse? What does it have to do with what I said?

In my opinion discussing interpretations has become popular among laymen, while working physicists rather discuss physics and do not care about interpretations at all, especially in experimental physics. Most working physicists I know are already quite annoyed when another bad pop-sci summary about some nature or science article comes out claiming things being in several places at once, backward causation or fancy non-locality effect because the stuff in the pop sci summary is never claimed in the article itself and one can be sure that friends, relatives and that unknown guy on the bus who somehow heard that you do quantum physics for a living will ask you about how that works and one needs to spend a lot of time in order to undo all the damage already done by those pop-sci summaries which just try to make things sound sensational.

I recently met a guy working on nanomechanics and they got a mechanical resonator close to the ground state already a few years ago. Some journalist came over and asked him what that might be good for and he answered that the resonance frequency might change if some atoms or molecules settle on the oscillator, so one might identify some elements as a long term goal. The headline of the final article was: Scientists develop artificial nose...

That'd be great for a post of facebook but is out of place here. Can you please explain why the nonlocal guiding wave would mimic superpositions of states when a quasi-macro or macro system is isolated from the environment?

 

[kith]

I was hoping for an explanation from your point of view how the non-local guiding wave is compatible with the superpositions of states the said guiding wave was supposed to do away with (for a somewhat classical and intuitive picture of the world).

You really have to distinguish between superpositions and multiple states at the same time. In classical electrodynamics, we have superpositions as well. This doesn't imply that there are multiple states. At a time t₀, a unique state is given by the electric field E(x,t₀), the magnetic field B(x,t₀) and their derivatives. In dBB, a unique state of a particle is given by its position x₀ and its guiding field ψ(x,t₀) (note that this doesn't depend on the system being "microscopic"). It doesn't make sense to claim that dBB is proven wrong by experiments which have reconstructed a certain ψ from their measurements unless dBB predicts a different ψ for this situation.

 

[kith]

How does the ensemble interpretation work in cosmology? What are the multiple preparations in observing the anisotropy of the microwave background?

The microwave background corresponds to a mixed state which is interpreted as an ensemble in all interpretations. I'm not sure what you are getting at.

 

[Ken G]

The key issue is how such a world emerges from a theory that only makes predictions about observations that appear in such a world. That is a very deep issue and the true quantum mystery.

I agree that is the central issue, but I'd frame it differently. I don't hold that worlds ever emerge from theories, since I reject the concept that nature follows mathematics. Instead, it seems closer to what actually happens that we fit mathematics to nature like a template or a (sometimes amazingly) close approximation. Given that, it is perfectly natural to expect that all physical theories must involve predictions about observations, so the inscrutable nature of an observation should always be difficult or impossible to remove from any theory. So for me, the deep question is, what is the connection between observations and mathematics? They seem like two completely different things, but apparently they are quite deeply connected. That we cannot understand the connection is not cause to imagine it isn't there, as the success of physics shows that connection is quite clearly there. So we should not make it our goal to remove the connection, but rather to accept it, study it, and understand it better.

A lot of progress has been made - but issues still remain and more research is required before a satisfactory explanation is found. I suspect a few revolutions will occur along the way - indeed we may be in the middle of one right now - I find the following very thought provoking:
https://www.simonsfoundation.org/quanta/20130917-a-jewel-at-the-heart-of-quantum-physics/

Wow, that's potentially monumental. I would cull out this quote:“They are very powerful calculational techniques, but they are also incredibly suggestive,” Skinner said. “They suggest that thinking in terms of space-time was not the right way of going about this.”

What is the significance that one of our central conceptual tools for organizing our perceptions, space and time, is "not the right way of going about this"? It would seem that this is trying to tell us that tools we use to organize our perceptions are not always the best way to organize observations writ large. This is a bit like what Planck was quoted as saying earlier in this thread-- our ability to observe is changing, when we do modern physics we rely more and more on supplemental apparatuses than the simple perceptions we use in our daily lives. The need for new mathematics appears with the ability to do new types of observations, and the organizational milieu that worked before is no longer the most elegant approach. First it was imaginary numbers that rose to the fore, now it may be strings or amplituhedrons.

We proceed in steps-- first we have new observations that stimulate new mathematical structures, then we spend a lot of time understanding our own mathematical structures (which tend to be more profound and more elegant than we realize when we first describe them), then we get all excited we have figured out how nature really works, then come the next generation of new observations that show us it ain't. I say it's time we recognize this cycle as the natural progress of science, and stop trying to make it what it never was.

Added: The role of observation does not mean that when a tree falls, we can be unclear about if it makes noise. Instead, that role is in giving meaning to the predicate, that "a tree falls." Asserting a falling tree already asserts all that goes with it, including noise, but the assertion itself is already an observational one. That is the part people often forget. The proof is that as yet we have no idea if there is any difference between saying "a tree falls" and "a tree is observed to fall." For the time being, we mean exactly the same thing by those two phrases, as we have no other meaning for any of those words.

 

[TrickyDicky]

Really interesting thread and must say I find myself attracted the ensemble interpretation as a bare minimum interpratation of the math. However it is not without some complexities as any intepretation.
I was wondering (always from my laymen-nonexpert-naive point of view) how is this interpretation made compatible with QFT where the wavefunction can be seen as a field operator observable, the emphasis usually put in saying this operator is different from the wavefunction of a single particle, but this distinction being moot in the ensemble interpretation as the wavefunction here is never interpreted as that of a single particle if I understood correctly.

 

[Ken G]

It's a new development and the guiding wave is in trouble with experiments. On the other hand, quantum mechanics has no problems with superpositions and quantum weirdness.

As you keep saying, but you have not made the case. You keep saying that in effect, "Bohm would not have expected experiment X to come out the way it does." I think that is quite untrue, I believe there are no experiments that have ever been done that Bohm would have thought would come out any differently. Indeed, I would say this is obvious, because if there were, then you could point to the equation in BM that fails, yet the equations in BM are built to produce the equations of QM. So if such an experiment really existed, that would surprise Bohm, the project would not be to show where BM went wrong, the project would be to show where the Schroedinger equation went wrong.

 

[atyy]

The microwave background corresponds to a mixed state which is interpreted as an ensemble in all interpretations. I'm not sure what you are getting at.

If I understand correctly, the ensemble interpretation says quantum mechanics applies to many physical copies of the system. What are the many physical copies of the system when the system is the universe, eg. for the following application of quantum mechanics by Mukhanov?

Mukhanov, Physical Foundations of Cosmology, Section 8.4
"How do quantum fluctuations become classical? When we look at the sky we see the galaxies in certain positions. If these galaxies originated from initial quantum fluctuations, a natural question arises: how does a galaxy, e.g. Andromeda, find itself at a particular place if the initial vacuum state was translational-invariant with no preferred position in space? Quantum mechanical unitary evolution does not destroy translational invariance and hence the answer to this question must lie in the transition from quantum fluctuations to classical inhomogeneities. Decoherence is a necessary condition for the emergence of classical inhomogeneities and can easily be justified for amplified cosmological perturbations. However, decoherence is not sufficient to explain the breaking of translational invariance. It can be shown that as a result of unitary evolution we obtain a state which is a superposition of many macroscopically different states, each corresponding to a particular realization of galaxy distribution. Most of these realizations have the same statistical properties. Such a state is a close cosmic analog of the "Schroedinger cat." Therefore, to pick an observed macroscopic state from the superposition we have to appeal either to Bohr’s reduction postulate or to Everett’s many-worlds interpretation of quantum mechanics. The first possibility does not look convincing in the cosmological context."

 

[bohm2]

Superpositions were and are troublesome for the idea of macro realism, Bohm's idea was to restore objectivity by removing superpositions of states. He was wrong...BTW, it's not allowed to link to blogs here. I took a look at the answers and none addressed the issue I raised above. If nobody can answer this, they are wrong and would rather believe in a conspiracy(the pilot wave has a new function - it has to perform complex conspiratorial acts to suit someone's agenda).

I apologize for that. I will not post blogs again but if responses in your previous thread topic from both theoretical and experimental physicists did not convince you, then I have no hope in hell, since there's nothing I can add.

Do the SQUID experiments falsify Bohmian mechanics?
https://www.physicsforums.com/showthread.php?t=610085

 

[Ken G]

I don't understand this part. What is a formal mathematical meaning of an interpretation?

The Wiki on the logic of mathematical theories puts it pretty well I think when it says "An interpretation of a theory is the relationship between a theory and some contensive subject matter when there is a many-to-one correspondence between certain elementary statements of the theory, and certain contensive statements related to the subject matter." I'm not a mathematician, but my general impression is that a formal interpretation is basically an encoding of a theory into terms that have semantic meaning. In other words, an interpretation is a semantic picture we can attach to a theory, that contains enough information to derive the theory, but adds additional context that is not unique because it goes outside the theory proper. It is really the difference between how one proves a theorem (which is syntactic) and how one understands a theorem (which is semantic). The different roles of syntax and semantics in mathematics maps into the difference between the predictions of a physics theory, and statements about "what is happening."

Maybe I'm misunderstanding your point but as I see it, Fuchs, of all people, wrote a good paragraph worth regurgitating:

Interview with a Quantum Bayesian
http://arxiv.org/pdf/1207.2141v1.pdf

Fuchs' view is tantalizing, but it doesn't seem to be on solid formal footing. I think he is basically saying, physics is done by physicists, so whatever the physicist is picturing in their mind as they write down the equations is central to what physics is. He is also saying that our job is to understand nature, not just predict it. That's all true, but we must also bear in mind that we want objectivity in science as well. So we must tolerate different subjective interpretations of what is happening, because we cannot adjudicate them by experiment. Indeed, I should even say "embrace" rather than "tolerate." So perhaps the common ground between what I'm saying and what Fuchs is saying is, instead of saying "The interpretation should come first; the mathematics (i.e., the pre-existing, universally recognized thing everyone thought they were talking about before an interpretation) should be secondary," we should say the interpretation should come first to the individual physicist doing physics, but not necessarily the same interpretation for all. In that sense, an interpretation has some of the same status as a reference frame.

 

[Ken G]

If I understand correctly, the ensemble interpretation says quantum mechanics applies to many physical copies of the system. What are the many physical copies of the system when the system is the universe, eg. for the following application of quantum mechanics by Mukhanov?

I believe your question was answered above by bhobba, when he stressed that the ensemble is a conceptual tool, not a physical entity, in cases where there is only one realization of the system under study (like the universe). In effect, an ensemble interpretation of the CMB is a multiverse picture, but it differs from the standard multiverse picture in the sense that it does not require we view the multiverse as something real, but rather as a conceptual device. The same could be said for how the ensemble interpretation regards Everett's many worlds. One can get all the expository benefits of Everett's picture using the ensemble picture, yet without holding that decohered subspaces of the unitary superposition continue to be real even after the decoherence has assured no information can cross between them. In short, the ensemble picture is what you get when you cross many-worlds with the CI, and notice that you can eliminate all the seeming contradictions by simply throwing out everything that requires taking QM mechanics "seriously" as a description of what is actually happening.

 

[atyy]

I believe your question was answered above by bhobba, when he stressed that the ensemble is a conceptual tool, not a physical entity, in cases where there is only one realization of the system under study (like the universe). In effect, an ensemble interpretation of the CMB is a multiverse picture, but it differs from the standard multiverse picture in the sense that it does not require we view the multiverse as something real, but rather as a conceptual device. The same could be said for how the ensemble interpretation regards Everett's many worlds. One can get all the expository benefits of Everett's picture using the ensemble picture, yet without holding that decohered subspaces of the unitary superposition continue to be real even after the decoherence has assured no information can cross between them. In short, the ensemble picture is what you get when you cross many-worlds with the CI, and notice that you can eliminate all the seeming contradictions by simply throwing out everything that requires taking QM mechanics "seriously" as a description of what is actually happening.

bhobba, can you confirm this? It seems different from Ballentine 1970 http://www.kevinaylward.co.uk/qm/ballentine_ensemble_interpretation_1970.pdf , p361: "Because this ensemble is not merely a representative or calculational device, but rather it can and must be realized experimentally"

 

[bhobba]

bhobba, can you confirm this? It seems different from Ballentine 1970 http://www.kevinaylward.co.uk/qm/ballentine_ensemble_interpretation_1970.pdf , p361: "Because this ensemble is not merely a representative or calculational device, but rather it can and must be realized experimentally"

Yea - I think I have mentioned a number of times that Ballentine seems to have changed his view between writing that paper and the book.

I gave the quote from his book that clearly shows he now views it as purely conceptual.

Thanks
Bill

 

[Maui]

You really have to distinguish between superpositions and multiple states at the same time. In classical electrodynamics, we have superpositions as well. This doesn't imply that there are multiple states. At a time t₀, a unique state is given by the electric field E(x,t₀), the magnetic field B(x,t₀) and their derivatives. In dBB, a unique state of a particle is given by its position x₀ and its guiding field ψ(x,t₀) (note that this doesn't depend on the system being "microscopic"). It doesn't make sense to claim that dBB is proven wrong by experiments which have reconstructed a certain ψ from their measurements unless dBB predicts a different ψ for this situation.

I don't see what this is supposed to prove or in what way it answers my question, but a system in superposition does not have a unique state but occupies all possible quantum states simulataneously. In DeBB every particle has a unique position at all times(the experiements I cited rule this out), whereas the wave spreads throughout the universe.

 

[kith]

It seems different from Ballentine 1970 http://www.kevinaylward.co.uk/qm/ballentine_ensemble_interpretation_1970.pdf , p361: "Because this ensemble is not merely a representative or calculational device, but rather it can and must be realized experimentally"

I'm not sure how big this difference really is. For example if you need multiple copies of the universe, your theory doesn't apply to the universe because you don't have these copies. The conceptual ensemble view applies but how would you determine the state of the universe? You can't even in principle because you would have to determine your own state, too. So I think these may be two sides of the same coin.

 

[kith]

I don't see what this is supposed to prove or in what way it answers my question, but a system in superposition does not have a unique state but occupies all possible quantum states simulataneously.

That's wrong. Please write down a superposition which is not a unique state.

 

[Maui]

I apologize for that. I will not post blogs again but if responses in your previous thread topic from both theoretical and experimental physicists did not convince you, then I have no hope in hell, since there's nothing I can add.

Do the SQUID experiments falsify Bohmian mechanics?
https://www.physicsforums.com/showthread.php?t=610085

Obviously you do not understand what the debate is about. The views are 100.00% opinions(expressed as facts) that are now even funnier to hold in light of the further experimental and practical developments in the field. But if you think someone's opinion and interpretations are what you are looking for and do not need to bother yourself with the details, ok.

 

[Maui]

That's wrong. Please write down a superposition which is not a unique state.

You can prepare an electron into a state where there is a 50/50 percent probability of finding it in a spin up or down state e.g.

|\psi> =(1/2)|up>+(1/2)|down>

 

[kith]

|\psi> =(1/2)|up>+(1/2)|down>

The unique quantum state of this superposition is |\psi>. So you are wrong.

 

[Nugatory]

a system in superposition does not have a unique state but occupies all possible quantum states simulataneously.

You've said this about 93 bazillion times now, but I still don't see how it makes sense when applied to even the simplest states. If I pass a particle through a horizontally oriented Stern-Gerlach device, and it is deflected to the right, is it not in the unique state "spin right"? And is it not also in a superposition of spin up and spin down?

 

[Maui]

The unique quantum state of this superposition is |\psi>. So you are wrong.

OK but the spin is not definite until a measurement is made. Care to address the point I made instead of delving into semantics?

 

[Nugatory]

You can prepare an electron into a state where there is a 50/50 percent probability of finding it in a spin up or down state e.g.

|\psi> =(1/2)|up>+(1/2)|down>

True, but the preparation procedure consists of passing the electron through a horizontally oriented Stern-Gerlach device, leaving it in the unique state $|right\rangle$.

 

[kith]

OK but the spin is not definite until a measurement is made. Care to address the point I made instead of delving into semantics?

This isn't about semantics at all but about the very core of the issue.

First of all, note that you have written "not definite" which is very different from your previous assertions that it is "both at once". If it is "not definite", we can supplement QM with something else to make it definite. dBB does this and unless you can derive contradictions with established experimental results from dBB, this point of view has to be valid.

Secondly, being "in" a superposition is not a property of the system. The system is in its unique quantum state. Whether this state is a superposition of eigenstates or not depends on the measurement you are going to perform. Your electron state "psi" is the eigenstate "up" of a certain alignment of the measurement apparatus (Nugatory called it "right" which is just a different name), the eigenstate "down" of another alignment and a superposition of eigenstates with respect to various other alignments. It all depends on the measurement you are going to perform.

 

[Ken G]

Yes, I think this discussion is bringing out the problems that appear when we think of a superposition as being a function of the system, rather than a function of the relationship between a preparing measurement and a concluding measurement, mediated by some system. The coordinates of a superposition are matrix elements like <i|f>, where <i| is the outcome of the preparing measurement, and |f> is the (presumably hypothetical) outcome of the concluding measurement. Quantum mechanics predicts those coordinates, interpreted as probability amplitudes. The system isn't "in" any of those states, the relationship is between measurements.

 

[kith]

The system isn't "in" any of those states, the relationship is between measurements.

This requires a very broad definition of measurement. For example I wouldn't call the interactions which lead to observable quantum effects in astrophysics "measurements".

 

[Ken G]

Yes, I don't mean to parse those kinds of distinctions, it certainly isn't easy to do so! For me, a "measurement" can be interpreted broadly, as any phenomenon that fits into the general language we use to interpret quantitative objectively studied outcomes, without itself necessarily being a quantitative objectively studied outcome.

 

[Len M]

There isn't. The junk you read in the popular press may be true. That's not the point, or why it generally makes me want to run away screaming - the point is they say it as if its the only view. A much more rational view exists - for example bog standard CI is much more rational than this observer created tripe - but they don't say it - because its not 'sensationalist' enough.

When was the last time you saw any populist book say Copenhagen assumes a world out there entirely common-sensical, trees make sounds when there is no observer, and all our every day intuition holds true? That's not going to sell is it - so they don't say it. But that is precisely what Copenhagen, and the Ensemble interpretation this thread is about says.

I understand that what you say above is entirely in the context of CI being miss represented, and it is within the outline of that interpretation you make the remarks concerning “observer created tripe” and “trees making sounds when there is no observer” and I don't want to detract from that at all.

However I would just like to step outside of any interpretation of QM and its relationship with our macroscopic reality and make just a few comments concerning those two remarks in the context of how I see realism, idealism and the role of physics.

I think that the falling tree and its sound is a much misunderstood scenario. What can we say about that scenario outside of phenomena? In the same vein, what can we say about the birth of stars before humans ever came on the scene? All we can actually say is that we extrapolate the experience of phenomena to these events as if there were a hypothetical sentient being present at the birth of the star and present when the tree falls. What actually exists without these hypothetical sentient beings present to record the experiences is unknown and will always be unknown because we cannot do physics without invoking observation and measurement which by definition invokes phenomena.

What (if anything) exists outside of phenomena belongs within mind independent reality. Thus, what exists outside of the falling tree or the birth of a star with no reference to phenomena (hence humans) is a matter for philosophical speculation and manifests itself in terms of various flavours of realism (or idealism if one thinks there is only phenomena). The philosophical stance one adopts, whether naive realism (a one to one relationship between mind independent reality and phenomena) or radical idealism (there is no mind independent reality only phenomena) cannot be judged to be right or wrong by anyone, rather those philosophical stances should be distinguished from what physics proper provides us within empirical reality (i.e. observer dependent reality) in terms of mathematical predictive models along with the interpretations involving interactions between phenomena.

 

[my2cts]

The advantage of Ballentine's is that is void of unnecessary and possibly unwarranted assumptions, so it is a good starting point for thinking about the interpretation of QM.

 

[bohm2]

I don't see what this is supposed to prove or in what way it answers my question, but a system in superposition does not have a unique state but occupies all possible quantum states simulataneously. In DeBB every particle has a unique position at all times(the experiments I cited rule this out), whereas the wave spreads throughout the universe.

As an aside, in BM there's a difference between the position operator and actual particle (Bohmian) position. The former is treated as all other operators as in usual QM (i.e. useful mathematical devices for calculation of statistics of experimental results).

 

[Cthugha]

Experiment says so, you live in the 1940's. Small scale prototypes of quantum computers have already been implemented and I posted links earlier in the thread.

Yes, I know. So what? That still does not back your point. You claim quantum computers need a certain interpretation of qm. They do not. They work just as well in interpretations without superposition like for example MWI (which I dislike just like BI).

That'd be all good if superpositions were not experimentally confirmed. You are completely wrong, that's why you turn this into what the maths of the BI says(it's the math that needs interpretation!). It's an interpretation, it's supposed to explain classical behavior and it does so using a pilot wave. No wonder you don't mention it anywhere.

Ehm, no. I have not been talking about what the math in BI says so far simply because I am not an expert on BI and do not intend to become one. I was talking about what the math of qm says - completely independent of applying any unnecessary interpretation.
Superpositions in the that sense: yes, they have found to be the mathematical model of choice. That still does not mean that people have shown that things exist in two states at once - people have shown the cool physics resulting from indistinguishability. I work in a lab trying to implement electron sins in quantum dots for quantum information purposes. The guys on that experiment really want to smash their head against the wall every time they hear this nonsense. I am working on superpositions in terms of vacuum Rabi oscillations and people in my field are also sick of that stuff. The point of view that particles really exist in two positions at once is rarely held by working physicists. Most experimentalists really do not care about how to interpret indistinguishability and the interferences that follow.

That's the same as asking for direct contact(touch) with the Sun to believe that it exists. And you know what you require is not possible but it's a shelter, when you have no other way out.

No, it is not. You are creating a straw man here.

What are you talking about? We are discussing superpositions of states and you are misinforming people that qm doesn't care about it. That's the ABC of qm, so what are you talking about?

Superposition of states is not the same as existing in two states at once. QM cares about linear superposition of states, but not about whether you want to consider the wave function as real and whether you want to interpret superpositions as two states being realized at the same time. If you think the latter is the abc of qm, I suggest picking up a good book on qm and learning what it really says about the meaning of indistinguishability.

How did it get to discussing collapse? What does it have to do with what I said?

Just another popular myth introduced by pop-sci summaries.

Can you please explain why the nonlocal guiding wave would mimic superpositions of states when a quasi-macro or macro system is isolated from the environment?

I am by no means an expert on BI, but if I remember correctly, the guiding wave acts as a potential and for ensembles of particles with unknown initial conditions as given by the uncertainty relation you end up with average trajectories equivalent to those governed by a probability distribution given by "things existing in two places at once". However, there are people on these forums who know that stuff way better than I do as I stick to the minimalist interpretation and do not care about going further. I agree that assuming weird trajectories seems artificial, but people have already shown experimentally that if you use weak measurements to examine the average(!) trajectories of single particles in a simple two-slit interference experiment, you really get these weird trajectories as the experimental result (see "Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer" by Kocsis et al., Science 332, 1170 (2011). Bare qm predicts the same weird average trajectories that BI does.

I don't see what this is supposed to prove or in what way it answers my question, but a system in superposition does not have a unique state but occupies all possible quantum states simulataneously.

As has been said before this is where you go wrong. There is nothing in QM which needs that. There is absolutely no reason to assume that a system is really in several states at once. There is also no reason against it. This is simply interpretation. Pure opinion. Or can you point out any experimental result supporting your point of view that one has to interpret qm your way? If so, please provide a reference.

 

[bhobba]

I think that the falling tree and its sound is a much misunderstood scenario. What can we say about that scenario outside of phenomena?

What I am talking about is the common sense view of the world that scientists and applied mathematicians more or less take for granted. What you are talking about is philosophical reflection which is something different again.

Now I don't want to run such down, it obviously interests those of a certain bent, but unless it leads to testable predictions it's not really science. That's why guys like me usually don't worry about it.

You are correct in the point I was making, but there was also another point. There is no need to depart from everyday commonsense ideas unless forced to do so. The exact departure from those ideas QM requires is often misrepresented.

Thanks
Bill

 

[bhobba]

Superpositions in the that sense: yes, they have found to be the mathematical model of choice. That still does not mean that people have shown that things exist in two states at once - people have shown the cool physics resulting from indistinguishability.

As has been said before this is where you go wrong. There is nothing in QM which needs that. There is absolutely no reason to assume that a system is really in several states at once. There is also no reason against it. This is simply interpretation. Pure opinion. Or can you point out any experimental result supporting your point of view that one has to interpret qm your way? If so, please provide a reference.

I think one of the issues here is the influence of older textbooks such as Dirac's Principles of Quantum Mechanics.

I actually learned proper QM from that book and Von Neumann's classic many moons ago - just after my degree over 30 years ago now - was it that long - seems like yesterday.

Anyway Dirac states the principle of superposition this way - from page 12:
'It requires us to assume that between these states there exists peculiar relationships such that whenever the system is definitely in one state we can consider it partly in each of two or more states'

The problem is that really is an interpretive statement not actually implied by the formalism. However it undoubtedly had a strong influence on a whole generation and permeated through such discussions as this in an unchallenged sort of way.

Contrast this with Ballentine's approach which doesn't really state such - it rather is encoded in his second axiom - given an observable A, the expected value of an observation represented by that observable is Trace (AP) where P is a positive operator of unit trace and is defined as the state. In fact that follows from the representation of observables as Hermitian operators via Gleason's Theorem. This engenders an entirely different view - the state is simply something required by the formalism to help us calculate the expected outcomes. Systems do not exist in states - its more like probabilities - which also help us calculate expected values. They too can be viewed as states by writing them as vectors. Coins, dices etc do not exist in such states - they are simply used to help us calculate long term averages of a large number of trials, events or whatever terminology you want to use. Viewed this way its an entirely different paradigm than Dirac's and IMHO much less likely to lead to confusion.

Thanks
Bill

 

[Maui]

Yes, I know. So what? That still does not back your point. You claim quantum computers need a certain interpretation of qm. They do not. They work just as well in interpretations without superposition like for example MWI (which I dislike just like BI).

I do not claim that(show me where I did, or I will report you for spreading misinformation!)

I did claim that particles in BM had definite positions at all times which is contradicted in experiments and prototypes of quantum computers that were already tested(so particles cannot have definite position at all times, experiements, however short, prove that this is not so). So no, I did not claim what you I did.

Ehm, no. I have not been talking about what the math in BI says so far simply because I am not an expert on BI and do not intend to become one. I was talking about what the math of qm says - completely independent of applying any unnecessary interpretation.
Superpositions in the that sense: yes, they have found to be the mathematical model of choice. That still does not mean that people have shown that things exist in two states at once - people have shown the cool physics resulting from indistinguishability.

Can you show that a quantum computer uses indistiguishibility of particles instead of superpositions? Preferably something peer reviewed and not a random opinion, like the opinions expressed in this thread.

I work in a lab trying to implement electron sins in quantum dots for quantum information purposes. The guys on that experiment really want to smash their head against the wall every time they hear this nonsense. I am working on superpositions in terms of vacuum Rabi oscillations and people in my field are also sick of that stuff. The point of view that particles really exist in two positions at once is rarely held by working physicists. Most experimentalists really do not care about how to interpret indistinguishability and the interferences that follow.

You can write a rebuttal to the researches that implemented the first quantum computer at MIT and the Institute of Waterloo because they say:

Superposition and Entanglement? Pardon?

It’s OK to be a bit baffled by these concepts, since we don’t experience them in our day-to-day lives. It’s only when you look at the tiniest quantum particles – atoms, electrons, photons and the like – that you see intriguing things like superposition and entanglement.

Superposition is essentially the ability of a quantum system to be in multiple states at the same time — that is, something can be “here” and “there,” or “up” and “down” at the same time.

Entanglement is an extremely strong correlation that exists between quantum particles — so strong, in fact, that two or more quantum particles can be inextricably linked in perfect unison, even if separated by great distances. the particles remain perfectly correlated even if separated by great distances. The particles are so intrinsically connected, they can be said to “dance” in instantaneous, perfect unison, even when placed at opposite ends of the universe. This seemingly impossible connection inspired Einstein to describe entanglement as “spooky action at a distance.”

Why do these quantum effects matter?

First of all, they’re fascinating. Even better, they’ll be extremely useful to the future of computing and communications technology.

Thanks to superposition and entanglement, a quantum computer can process a vast number of calculations simultaneously. Think of it this way: whereas a classical computer works with ones and zeros, a quantum computer will have the advantage of using ones, zeros and “superpositions” of ones and zeros. Certain difficult tasks that have long been thought impossible (or “intractable”) for classical computers will be achieved quickly and efficiently by a quantum computer.

http://iqc.uwaterloo.ca/welcome/quantum-computing-101

Superposition of states is not the same as existing in two states at once.

Says who? Your word against experimentalists that have already proven you wrong multiple times? I can also post random noise but have little time for that.

 

[Maui]

First of all, note that you have written "not definite" which is very different from your previous assertions that it is "both at once".

Now I do again, it's in both states at once and my assertion is backed by experiment and technology already out there.

Your opinion is backed by what? Theory from the 1930's or your personal preference?

Spin based quantum computing has already been implemented:

http://iqc.uwaterloo.ca/faculty-research/spin-based-quantum-information-processing

 

[Jano L.]

Sorry, I don't see how your explanation shows that two electrons that are shared and on unique trajectories between two atoms can hold the two atoms together.

I do not see that exactly either, unfortunately. The only directly understandable thing is that the Coulomb interaction for proton-electron is attractive, while the surrounding noise may allow the electrons to assume large range of possible states to conform to Schr. equation.

But I do not see the converse either; it is equally hard to prove that the electrons cannot move in trajectories. Since trajectories make a lot of sense otherwise, I prefer to assume they retain their validity. So it is just one of possible viewpoints.

The assertion that electrons follow unique trajectories(i.e. they are not in superposition of states)

Here you probably meant "at many places at the same time" instead of "superposition of states". The difference is the former refers to the electron, the latter to the function $\psi$ describing it (or more correctly, describing a system of many electrons and protons).

As you may have inferred from the above discussion, the view that superposition implies "being at many different states at the same time" has no solid ground in the mathematical theory. It is just something somebody once said and it was so mysterious that journalists keep writing it down to make their articles look "cool", while they only make them inaccurate.

...the paper you referenced that claims that background radiation keeps atoms from falling apart is wild speculation, not fact...

I did not claim it a fact. The paper assumes it to show its implications in the EM theory of point-like electron. Zero-point field (ZPF) is an additional assumption in the classical EM theory and necessary consequence of the commutation relations in quantum theory, of great explanatory value and proven success.

In classical theory, ZPF is the most natural thing to maintain charged particles in non-zero mutual distance and to prevent the infamous atomic collapse. In quantum theory, it is necessary to maintain commutation relations in time (see P. W. Milonni, Quantum Vacuum: An Introduction to Quantum Electrodynamics, Academic Press 1994, sec 2.6), which is motivated by the same reason.

It may be that our current picture of the zero-point field is inaccurate, for example the high-frequency tail of its spectrum, and the physical significance of the spectrum itself, but it is a fruitful idea that will stay with us for some time. Without it, we have little ideas left to explain why the atomic systems maintain their stable average size.

There are areas where high levels of cosmic or environmental radiation are very unlikely to be found(e.g. the Earth's core) ...

Not necessarily. The ZPF field is $assumed$ to be present everywhere, even in the Earth's core. Can you prove that is inconsistent with the basic equations? Maxwell's equations are linear, which means their solution can contain homogeneous solution which is uniform and isotropic in space. Can you show the presence of the matter will shield this kind of noisy field inside the Earth? Noise is hard to shield, especially its higher frequencies.

 

[kith]

Now I do again, it's in both states at once and my assertion is backed by experiment and technology already out there.

Yet still you haven't managed to show us the math of how dBB is supposed to fail. Curious, isn't it? I think I'm done with this discussion.