Originally Posted by El Hombre Invisible
I can't understand everything in your response because of typos and grammatical weirdness so forgive me if I don't reply to all your points.
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You are open to ask
Originally Posted by El Hombre Invisible
So that's direct observation out of the question.
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Always. One thing is the epistemological level (science) and other is the ontological one (phylosophy). QM works at epistemological level. Bohm theory works at the ontological level, asuming the existence of an underlying structure which cannot be observed, either directly or indirectly, as already said. Bohm theory is strictly speaking metaphysics.
Originally Posted by El Hombre Invisible
Are you? How do you know the light was "between" the monitor and your eyes. All you can say is your eyes are detecting light emitted by your monitor. Anything in between is speculation.
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Speculation? The engineers of my GoldStar 17'' do not think the same
Originally Posted by El Hombre Invisible
Not at all, I'm trying to make your argument stick to well accepted notions. The criteria you cite for dismissing the Bohm intepretation would also render other notions dead that clearly aren't. All I'm saying is that everything should be judged bu the same criteria.
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Under the same criteria, QM is physics and Bohm theory is
Pauli 1952.
Originally Posted by El Hombre Invisible
My question, Juan, was: is the inability to observe a quark grounds the dismiss it?
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If you cannot detect quarks, the theoretical interpretation is not, rigorously speaking, sound. Quark theory explains several things, but how do you know that the mathematical concept of quark is just an illusion? This is the reason that Gell-Mann initially claimed that quarks was not real particles. Perhaps are strings or spacetime knoks or the collective behavior of underlying particles still to be discovered, etc.
It appears very probable that quarks are real. But today, in the limits of my knowledge, are not unambiguously detected.
Originally Posted by El Hombre Invisible
This is a bogus argument. The manifestation of uncertainty in position and momentum is observed. Does this mean the particle HAS no exact position or momentum, or does it mean that no precise position or momentum can be OBSERVED? One does not mean the other. Uncertainty in position and momentum is explained in the Bohm interpretation, while the actual position and momentum themselves are precise. The reason why position and momentum cannot be known together is not a physical one - it is a mathematical one. The wave model of a particle with precise momentum is infinite in space along the direction of momentum. The wave model of a particle with precise position is a superposition of an infinite number of deBroglie waves. This does not itself rule out the particle having a physical exact position and momentum - it speaks only for the model.
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Is the point!
The manifestation of uncertainty mean that position and momentum cannot be defined togheter due to complementarity, and this IS verified by experience. If you apply classical mechanics you fail.
You cannot claim that particle HAS exact position or momentum if you cannot measure it NEWER. Precisely, the main hipothesis of Bohm theory is that there is an underlyng dynamical structure is HIDDEN. But if is HIDDEN cannot be OBSERVED and if cannot be OBSERVED then does not exist for SCIENCE.
Again i remark that Bohm theory belongs to metaphysics
It is not true that uncertainty in position and momentum is explained in the Bohm interpretation from actual precise position and momentum.
Because 1) those supposed precise position and momentum are HIDDEN in the "real" world accesible to science -belonging just to a world of "ideas"-. 2) Bohm does not explain how probabilities arise from an underlying deterministic HIDDEN structure.
The reason why position and momentum cannot be known together IS physical one. It is the principle of complementarity.
I think that you are again confusing epistemological with ontological models. You claim that QM is a model and that particles have both momentum and position. Well, the only "alternative" model of REALITY that I know is Bohm theory which claims that position and momentum are precise definite values BUT cannot be measured, even in principle! Then Bohm cannot shows that those precise values EXIST. It is just a phylosophical model.
You appears interested in substituting a well-proven physical model of reality by a methaphysical one, which, moreover, is less sucessful than QM for laboratory predictions.
Originally Posted by El Hombre Invisible
I find a huge contradiction in this argument as a whole. You tell me the Bohm interpretation cannot be experimentally verified then, to prove it is wrong, you link a paper recording the results of an experiment to test the Bohm interpretation against standard QM. Either the B.I. can be experimental verified or that experiment means nothing. One part of your argument is wrong.
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I think that "Wrong" is not the correct word at least in a first insight; "metaphysical" is more accurate.
The contradiction is just in your head.
QM says A = 2 p
where p is a probability.
Bohm says that there are not real probabilities and that p = 96 X where X is a hidden variable that cannot be detected/measured even in principle.
If you cannot experimentally verify p is 96 X because X is HIDDEN (perhaps is p = 34564576598705938567457 B where B is a hidden temperature
), then you cannot test Bohm theory (nor my theory about hidden temperatures), just QM which says what is p.
Originally Posted by El Hombre Invisible
Let me use an analogy - the electromagnetic field. What was that? It was a hypothesised physical thing that emanated from charged particles so that the field of one charge can act directly on the other charge itself without the two meeting. So what was being observed here? Not the field, but the effects of the proximity of one charge to another - i.e. motion due to that proximity. The electric field could not be directly observed. Even fluctuations in it could not be seen directly, only their hypothesised existence correlated to the supposed effects on electrons in measuring apparatus (such as eyes). Now replace electric field with quantum potential. Likewise, the quantum potential itself cannot be observed. Nonetheless, the Bohm interpretation does tell us that the potential of one particle will act on the other, so there will be an observable difference between an electron passing through a double-slit untouched and one doing so in the presence of a light source. The difference, of course, is that the results of this experiment were known and predictable before the Bohm interpretation existed - i.e. the mechanics of QM were well known before anyone postulated why they were as they were - while the postulate of the electric field was less after the fact. What lended credance to the electric field hypothesis was the success with experimental verification. In the case of the Bohm interpretation, the experimental predictions can be made without it - we have the mathematical (non-physical) model and know it works. By your argument, while the mathematical model of an electric field (like QM) was obviously successful, the physical notion of a field should have been discredit based on its invisibility. This wasn't the case - the model was overthrown by experimental observation, not the fact that the field was hidden.
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But 1) EM fields can be indirectly measured in some situations. For example in absence of magnetic effects
E = (1/e) dp/dt
from Lorentz force. Both e and dp/dt can be measured.
2) Precisely many authors reject the existence of fields. There are EM theories without fields, for example Feynman/Wheeler one. Really fields are not eliminated. Instead of being real physical objects by themselves, the fields in the FW formulation are
identities arising from particle trajectories.
3) The quantum potential is different. In FW formulation of EM, fields are functions of particle trajectories, which are observable
E = E(x y z)
In Bohm theory, the Quantum potential is function of unobserved things and does not appear to be very convenient even ignoring nonlinearities nonlocality, etc. Precisely some modern schools of Bohm theory (so called Bohmian school) say that is an unuseful artifact. For example D. Dürr, et al claim that the quantum potential may be ignored.
You have a very wrong conception of physical and mathematical models. QM is not a mathematical model and Bohm interpretation physical one.
Precisely is the inverse status. QM is physical (is a part of physics), and Bohm theory is methaphysical -or even if you prefer mathematical- model because has no link with measured reality.
Originally Posted by El Hombre Invisible
Okay, let's make a crowbar separation between the potential/pilot wave and the position/momentum of the particle. The reason being is that, if you start by accepting the Bohm interpretation, the potential IS observed by its correlation to the wavefunction of the particle, that is - observed to kind of the same extent as the electric field, for instance. That's the whole point - it's supposed to be a physical interpretation of the wave nature of matter as described by the wave function. The position/momentum thing IS hidden, as far as I understand, whatever happens. It can only be infered from accepting the Bohm intepretation, just like the fact that the gluon carries colour charge can only be infered from accepting QCD - that is, the only reason they must be accepted is that the model breaks down without their inclusion. They're both products not of observation, but of necessity for the success of the model.
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No, the potential is NOT observed, therefore is avoided by modern Bohmian School. No, it is not a physical interpretation because is based in unphysical postulates. Bohm model is not sucessful and QCD is not based in hidden variables.
Originally Posted by El Hombre Invisible
There's two things here. There's the graviton as a mathematical model to explain gravity on the quantum scale, and there's the physicality of the graviton, i.e. the physical interpretation of the graviton as a particle. What is being argued against here is the mathematical graviton as something that does not add anything to the ability to predict and analysis observations. What you are dismissing in the Bohm intepretation is (what is supposed to be) a physical intepretation of an already-existing and accepted mathematical model. Two different things. The graviton would be accepted if the mathematical model of it was subject to experimental verification. You still won't be able to 'see' a graviton any more than you may see the Bohm potential. All that matters is that it works, experimentally. The Bohm interpretation may not work as a physical interpretation of QM, like I said earlier, in which case it must be AMENDED or DISCARDED.
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Well, as brilliantly explained by Dyson, there are reasons for believing that graviton cannot be detected then the term quantum gravity is useless. I think that you are ignoring this very important point of Dyson discussion. Wthout posibility for detecting quantums of gravity there is no posibility for testing different versions of quantum gravity theories. Then dyson claim there is not physical reason for formulating a quantum theory of gravity based in gravitons.
What you are dismissing in the Bohm interpretation is that is NOT a physical interpretation of an already-existing and accepted mathematical model.
QM is a theoretical model, is not just math. And Bohm theory is not a physical model is a metaphysical model.
Originally Posted by El Hombre Invisible
Okay, what I meant was "an attempt at a physical intepretation of QM." This just goes back to what I said a few posts ago: if the physical model does not fully correspond to QM, it must be amended or discarded. Discrepancies between theory and evidence does not necessarily lead to the instant dismissal of that theory, though. Like I said, QM was not abandoned just because Pauli's electron gas model didn't fully work - you just fix it (if possible).
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The physical interpretation of QM is just the standard one. Read a book!
There is no reason for doing not search a better physical intepretation but Bohm
methaphysical one is not suitable like a substitute. This is reason that is rejected by almost all physicists.
Originally Posted by El Hombre Invisible
I thought it was.
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No it is not, because there is not direct contradiction between SR for low velocities (reduces to Newtonian mechanics) and non relativistic QM (e.g correspondence principle). Non relativistic QM is not applicable to high velocities and this is reason that exists a relativistic quantum theory. However nobody has formulated still a consistent relativistic generalization of Bohm theory precisely due to his strong incompatibility with SR.
Originally Posted by El Hombre Invisible
And up until the advent of relativistic QM, nobody had formulated it. Do you not see what I'm getting at here? There was a long period when QM and SR were incompatible. This did not mean QM had to be abandoned. The Bohm intepretation and SR are incompatible. Why does this mean the Bohm interpretation must be abandoned, rather than just formulating an SR-consistent Bohm model? Note, QM now is not consistent with GR, hence the postulated graviton. Don't see anyone abandoning QM on that basis.
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First part already replied. Second part:
It is not true that QM is not consistent with GR. QM applies to some problems and GR to others. That people is doing is searching an extended theory that can be applied to both sides there in the name quantum gravity (QG).
QG = quantum mechanics + gravity
You are very wrong in epistemological issues. QM does not need to be abandoned because any realistic QG theory may reduce to standard QM when G constant ---> 0.
Originally Posted by El Hombre Invisible
Don't need to. I have never said the wavefunction is physically explained in QM. You just keep telling me it's not. You're arguing against yourself. That's just crazy.
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No. i am not arguing myself. The wavefunction has no direct physical sense but indirect one as ALREADY explained -if you prefer we can talk about rays in Hilbert space-. Therefore, there is no problem with usual interpretation beyond usual ones of measurement problem. However, Bohm theory claim full physical sense for hidden variables, potential, etc.
This is the reason that is not seriously taken.
Originally Posted by El Hombre Invisible
Nope, the molecule itself has been diffracted. You'll have no trouble finding articles on it.
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I think that you do not know that a molecule is. Precisely, the nuclear framework of the molecule cannot be purely quantum because then there is not molecule just a bundle of atoms.
Originally Posted by El Hombre Invisible
No, I don't. I never said that.
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