Bohmian Mechanics

Originally posted by KazetNagorra
Actually, EM fields don't act at a distance (photons carry it). Gravity probably not either, although we have not directly measured the carriers of the gravitational force.

according to theory, the carriers of the gravitational force are gravitons.
But even before I heard of gravitons, rightly or wrongly, I accepted the idea something can act at a distance....because observation gave me no choice.

Originally posted by humy
according to theory, the carriers of the gravitational force are gravitons.
But even before I heard of gravitons, rightly or wrongly, I accepted the idea something can act at a distance....because observation gave me no choice.

Well, as it turns out there is nothing as far as we can tell that (causally) influences other things instantaneously.

Originally posted by humy
Newton's theory of gravity, unlike Copenhagen Interpretation of quantum mechanics, doesn't have the problem that it fails to explain such problems as the “measurement problem”.
See http://en.wikipedia.org/wiki/Measurement_problem
Thus, unlike with quantum mechanics, it is far from obvious what Newton's theory of gravity fails to explain that demands an explan ...[text shortened]... also don't have a problem with quantum tunneling. It isn't those things that I am suspicious of.

Newton's theory of gravity, unlike Copenhagen Interpretation of quantum mechanics, doesn't have the problem that it fails to explain such problems as the “measurement problem”.

That's because the measurement isn't even an issue to be raised in "newton's" formalism (actually in all of classical physics formalism)

Thus, unlike with quantum mechanics, it is far from obvious what Newton's theory of gravity fails to explain that demands an explanation and there is no need to add extra hidden variables (or whatever ) to explain some kind of 'strangeness' of Newton's theory of gravity.

Explain's Mercury's perihelion precession. Explain the correct factor of light bending due to gravity. Explain time dilation due to gravity. Explain how GPS works. Etc, etc, etc.
Explain how a body acts on another body instantaneously and without contact (a question that Newton knew that had to be answered and that's why he himself didn't fully trust his own theory of gravitation)

Plus I only mention Newton's theory of gravity to give an example of an elegant and with a great power of explanation and predictability that was "bested" by an even more elegant, more explanatory and greater predictability theory which is non-linear. So you totally missed my point.

Personally I don't have a problem with the "spooky action at a distance".

It doesn't matter with what you don't have or have a problem with because that's just like saying my prejudices are ok while the prejudice of people that are "orthodox quantum mechanics" aren't ok. That's not science and that's not even an argument. That's just huffing and puffing.

After all, we have such things as gravity, electric fields, magmatic fields etc that act at a distance.

So 18th century of you. Like kazetnagorra already said except for gravity we all "know" that none of those fields act at a distance.

I'll try to make to make my point more clear: why do people seem to be uncomfortable with the orthodox interpretation of quantum mechanics but seem to get along fine with hidden variables that need to be non-local (admittedly quantum mechanics by itself is nonlocal since it is founded on the Fourier transform formalism). The introduction of a pilot wave really is worth the bother of introducing ghost quantities whose only job is to explain what we see and nothing else? For me it clearly is not. But just in case it wasn't clear enough I am not a defender nor proponent of the Copenhagen interpretation. I'm not even a proponent of the Quantum Mechanics formalism as it is. For me we are in dire need of having to construct a theory of the quantum which is non-linear and maybe even local (the mathematical formalism to do this already exists in the form of wavelets.)

I also don't have a problem with quantum tunneling.

Good for you. Also nobody else (that I know of. Obviously I'm dismissing crackpots) have any problems with quantum tunneling. Why do you think you had to mention that.

Originally posted by adam warlock

Newton's theory of gravity, unlike Copenhagen Interpretation of quantum mechanics, doesn't have the problem that it fails to explain such problems as the “measurement problem”.

That's because the measurement isn't even an issue to be raised in "newton's" formalism (actually in all of classical physics formalism)

[quote]Thus, unlike w ...[text shortened]... g crackpots) have any problems with quantum tunneling. Why do you think you had to mention that.

Explain's Mercury's perihelion precession. Explain the correct factor of light bending due to gravity.

These are problems concerning conflict with observation, NOT problems with logical consistency or, as in this case when it comes to the measurement problem, vagueness of some aspect of what the theorem is saying.

It doesn't matter with what you don't have or have a problem with because that's just like saying my prejudices are ok while the prejudice of people that are "orthodox quantum mechanics" aren't ok. That's not science and that's not even an argument. That's just huffing and puffing.

I was not speaking of science. I was just giving the psychological reason (hence my later words “...rightly or wrongly ...” indicating I wasn't saying the acceptance was right! ) why I came to just accept action at a distance -that wasn't proposed as logical justification for such a belief! That acceptance may or may not be rational. I should have made that explicitly clear in that post to avoid misunderstanding but didn't -my failing.

Also nobody else (that I know of. Obviously I'm dismissing crackpots) have any problems with quantum tunneling.

I imagined that some laypeople who don't know much about physics may at the very least find it ant-intuitive. After all, in every day life, when you kick a football at a wall, the ball doesn't go through it (obviously I personally know that doesn't extrapolate to what happens at the very small scale )

Originally posted by humy

Explain's Mercury's perihelion precession. Explain the correct factor of light bending due to gravity.

These are problems concerning conflict with observation, NOT problems with logical consistency or, as in this case when it comes to the measurement problem, vagueness of some aspect of what the theorem is saying.

Quantum Mechanics is logically consistent and like I said previously in classical formalism the question of the "measurement problem" doesn't even exist so that comparison is unfair.

Also those questions that I've asked can perfectly be answered in the context of Newtonian's gravity while assuming ad hoc hypothesis, but nobody does that because it isn't elegant. But when dealing with quantum mechanics people happily add hypothesis just so they can reconcile the quantum mechanics description of the world with their prejudices.

Finally you made think about two articles that I've read a long time ago about QM and its interpretations:
1 - http://arxiv.org/abs/quant-ph/9609013 The Ithaca Interpretation of Quantum Mechanics
2 - http://arxiv.org/abs/quant-ph/9801057 What is quantum mechanics trying to tell us?

And this one

http://www.johnboccio.com/research/quantum/notes/mccall.pdf

provides a nice summary and synthesis of Mermin's argument.

Originally posted by black beetle
QM requires reality to be discontinuous, non-causal and non-local whilst, according to relativity theory, reality is supposed to be continuous, causal and local. In order to come up with a resolution, Bohm suggested that the two contradictory theories have a common: Undivided Wholeness.
Since, for one, non-locality is a fact and for two, under certain ...[text shortened]... x is caused by a single continuously connected wave medium;
There, a skeleton in the closet
😵

Very interesting, old bean.

Now, I guess if I were to finally dig up the time to tackle quantum mechanics, I would start with this book by Brian Hall:

http://www.amazon.com/Quantum-Theory-Mathematicians-Graduate-Mathematics/dp/146147115X/ref=pd_rhf_gw_p_img_3

I lack the patience to deal with books on the subject that are written by physicists for physicists. The notation is too wonky, for starters. And the constant use of hand-wavy "infinitesimals" (or "differentials" ) to represent "itty-bitty-teeny-tiny quantities" just makes me cringe outside the formal framework of differential forms on manifolds.

I may be "naive" here, but, it seems suspicious to me that the conventional interpretations of quantum physics seem to take the universe to be inherently probabilistic, as if the universe itself just doesn't know what it is doing, rather than taking the more conventional scientific approach of admitting that there are likely "hidden variables" underlying reality that we do not know about that make things appear to be probabilistic. That's what probability values always amount to: a reflection of what we don't know. It's not the universe's fault that we are so ignorant of its inner workings.

Originally posted by Soothfast
Very interesting, old bean.

Now, I guess if I were to finally dig up the time to tackle quantum mechanics, I would start with this book by Brian Hall:

http://www.amazon.com/Quantum-Theory-Mathematicians-Graduate-Mathematics/dp/146147115X/ref=pd_rhf_gw_p_img_3

I lack the patience to deal with books on the subject that are written by physicists for ...[text shortened]... hat we don't know. It's not the universe's fault that we are so ignorant of its inner workings.

It's a bit more subtle than that. Take for instance the Heisenberg uncertainty principle, which basically is just a statement that wave functions exist in the L^2 Hilbert space. For many simple cases, we know that the wave function evolves deterministically in time. But the description as wave functions means that a particle really doesn't have such a thing as a definite position, so a hidden variable that presumes that it does will fail, as Bell's inequality also shows. So while quantum mechanics does not give a conclusive answer to whether the universe is deterministic or not, it does show that the "classical" picture of particles having fixed position and momentum does fail.

Originally posted by Soothfast
Very interesting, old bean.

Now, I guess if I were to finally dig up the time to tackle quantum mechanics, I would start with this book by Brian Hall:

http://www.amazon.com/Quantum-Theory-Mathematicians-Graduate-Mathematics/dp/146147115X/ref=pd_rhf_gw_p_img_3

I lack the patience to deal with books on the subject that are written by physicists for ...[text shortened]... hat we don't know. It's not the universe's fault that we are so ignorant of its inner workings.

So I have that strange feeling that you gonna love ole David; according to him, there is an implicate order that enfolds the patterns of reality. When these patterns unfold into the realm of experience by means of a quantum process, we have the manifestation of the explicate order of the experienced reality. But what exactly do We perceive from the realm of experience, and which way?

The universal wavefunction envelops each single one self-measuring system (every observer contained within the observer universe), which self-organises (which “knows”, as you noticed) its wavefunction so that it splits into non-overlapping wave packets; in other words, each system creates its own measuring observable in a self-consistent way/ pattern, and then chooses the specific channel that wants to occupy. If the observation is repeatable the eigenstates of the system remain unchanged, whilst the observer change differently for each eigenfunction. Now, mind you: in fact the contents of the subjective awareness are constantly changing, whilst the ground aspect of the perpetual process (consiousness) remains relatively stable;

It follows that the self-measuring capability of consciousness is splitting out itself into viable probabilistic outcomes before collapsing the wavefunction into a specific outcome; another skeleton😵

Originally posted by KazetNagorra
But the description as wave functions means that a particle really doesn't have such a thing as a definite position, so a hidden variable that presumes that it does will fail, as Bell's inequality also shows.

Just a few clarifications to your comment:

1 - Bell's Theorem shows that orthodox quantum mechanics and quantum mechanics with local hidden make different predictions to what will happen to some correlation experiments. Until experiments are made non of the two approaches about quantum mechanics none of the theories can be said to be vindicated. Well, experiments can be made and, apparently (some people will claim a loophole or two in the experiments that were made), local hidden variables quantum mechanics are to be forgotten about. That of course still leave us with the task of ruling out if nature is just quantum mechanical (apparently a truly horrendous notion) or if it is non-local hidden variables quantum mechanical (apparently a more palatable notion).

Also Bell's theorem assumes a notion of scientific realism hence if nature is not scientific realist it may not apply (maybe this notion also is more palatable than orthodox quantum mechanics).

To finalize I must say that I've never heard or read (at the very least I don't remember it) someone interpreting Bell's theorem as saying that "a particle really doesn't have such a thing as a definite position". Can you please provide an argument that shows this or provide a link to an argument?

Originally posted by adam warlock
Just a few clarifications to your comment:

1 - Bell's Theorem shows that orthodox quantum mechanics and quantum mechanics with [b]local hidden make different predictions to what will happen to some correlation experiments. Until experiments are made non of the two approaches about quantum mechanics none of the theories can be said to be vindicate ...[text shortened]... position". Can you please provide an argument that shows this or provide a link to an argument?[/b]

Since Bell proved that EPR paper fails, Einstein's independent elements of reality (each single one of them with its own unique and separate on-board bit of information) are non-existent; it follows that, instead of Einstein's locality, existent is merely an interconnected pattern. Therefore, particles lack of any definite local attributes.
This is how I understand our KazetNagorra as regards this matter, but maybe I 'm wrong😵

Originally posted by adam warlock
Just a few clarifications to your comment:

1 - Bell's Theorem shows that orthodox quantum mechanics and quantum mechanics with [b]local hidden make different predictions to what will happen to some correlation experiments. Until experiments are made non of the two approaches about quantum mechanics none of the theories can be said to be vindicate ...[text shortened]... position". Can you please provide an argument that shows this or provide a link to an argument?[/b]

Bell's theorem implies that a local hidden variable theory assigning a definite position to a particle is wrong. Bohm's pilot waves attempt to subvert the issue by using a non-local theory, but the attempt seems very ad hoc to me. It seems more plausible to me that if a deterministic quantum theory can accurately describe nature, it is one that does not assign any definitie position to particles. But I have no emotional attachment to one result or the other and I'm happy to let the evidence speak for itself.

OK, it 's very close now at my local time zone.
MXmas to you all and yours,
May You Always Be Happy
😵

Originally posted by KazetNagorra
Bell's theorem implies that a local hidden variable theory assigning a definite position to a particle is wrong.

I took it to http://www.scholarpedia.org/article/Bell%27s_theorem and http://plato.stanford.edu/entries/bell-theorem/ and I couldn't find an argument for your assertion.

Originally posted by adam warlock
I took it to http://www.scholarpedia.org/article/Bell%27s_theorem and http://plato.stanford.edu/entries/bell-theorem/ and I couldn't find an argument for your assertion.

I'm certainly not an expert on Bell's theorem, but as I understand it, it concerns any kind of local hidden variable theory. That would naturally include theories that consider position as (described by) a local hidden variable.

Originally posted by black beetle
So I have that strange feeling that you gonna love ole David; according to him, there is an implicate order that enfolds the patterns of reality. When these patterns unfold into the realm of experience by means of a quantum process, we have the manifestation of the explicate order of the experienced reality. But what exactly do We perceive from the real ...[text shortened]... bilistic outcomes before collapsing the wavefunction into a specific outcome; another skeleton😵

I wasn't aware that David Bohm was involved in writings about philosophy of mind and neuropsychology. I reckon I ought to get a book of his, or two!

But I agree with others who say quantum mechanics, as a formal construct, is logically consistent. It is "merely" the interpretation of its consequences, and the consequences of quantum physics in general, that I have qualms with. At some point, when I've made a more thorough study of manifold theory, I intend to pick up the aforementioned book by Brian Hall which presents quantum mechanics for mathematicians, using the notation and logical constructs that I'm accustomed to.