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With respect to the "space" in which the wave function evolves, am I understanding these 4 positions accurately? If you favour one, which one do you favour and why?
1. David Albert:3N-dimensional space realism.
The space in which any realistic interpretation of quantum mechanics is necessarily going to depict the history of the world as playing itself out … is configuration-space. And whatever impression we have to the contrary (whatever impression we have, say, of living in a 3-dimensional space, or in a 4-dimensional space-time) is somehow flatly illusory...In reality, there is just a single 3N-dimensional wavefunction, and the division of reality into separate three-dimensional objects, including organisms, is just the product of our internal representation.
Problem: Why does the world appear 3-dimensional (or 4-dimensional if space-time) to us? What does N represent in 3N space (what is the space a configuration of, if not the particles)? (For Albert all that exists is a single particle, evolving one way or another in a very high-dimensional space). Maudlin finds this view hard to swallow because he finds it "obscure how something happening at a point (such as a particle occupying a point or a field being concentrated near a point) could be a complexly structured physical state of affairs...it is not easy to understand how those physical structures could constitute cats, or chairs, or people."
2. Monton/Lewis:3-dimensional space is fundamental. The 3N-dimensional space is an illusion/false as wave function is only a mathematical tool
While their arguments are somewhat different, both claim that the world really is 3-dimensional and the 3N-dimensional space is a kind of an illusion for different reasons. While Monton flatly rejects the reality of 3-N space ("the wave function is no more real than the numbers-such as 2 or p"), Lewis rules it out by arguing that the "dimensionality" of configuration space defining the wavefunction is not really "spatial". Both seem to deny the reality of the wave function.
Problem: Predictions of QM depend on the 3N-dimensional space that get lost in the 3-dimensional representation (e.g. information about correlations among different parts of the system, that are experimentally observed are left out).
3. T. Maudlin:3N-dimensional space is a mathematical tool but the wave function is "real" (in a unique way)
There are two distinct fundamental spaces (3-dimensional and 3N-dimensional), each with its own structure. What’s more, each space must possesses additional structure beyond what is normally attributed to it. Further structure is needed to ground the connections between the two fundamental spaces, saying which parts and dimensions of the high-dimensional space correspond to which parts and dimensions of ordinary space, and which axes of configuration space correspond to which particle.
Problem: Adds additional fundamental structure, making it less elegant/more complex.
Maudlin argues, that's fine, because such structure is needed to make an informationally complete description, from which "every physical fact about the situation can be recovered". With respect to the wavefunction structure, Maudlin doesn't make a commitment but suggests that it may be unlike anything else (sorta "physical"/real but in a unique/different way), kind of "in its own metaphysical category". He does appear (if I understand him and those that discuss his views) to regard configuration space as only a mathematical tool; however, he also regards the wave function as more than just a probability wave, even though we don't have direct access to it. This doesn't bother him as he writes: "If our only access to the wavefunction is via its effect on the particles, and if the connection to the lived world is primarily through the particles, then we are not constrained about the physical nature of the wavefunction."
4. Bohm:3N-dimensional space is a "real" information field represented in a "mind-like" entity represented by the wave function.
3-N space is an abstract multi-dimensional "informational space" that guides a particle evolving in 3-dimensional space.
Problem: How can an "informational field" guide the particle? How does it interact with it to inform it? The field acts on the particles but particle doesn't act on the field. Brown has argued that this goes against Einstein's action-reaction principle. Einstein wrote it is "contrary to the mode of scientific thinking...to conceive of a thing...which acts itself, but which cannot be acted upon."
Regardless this ontology requires far greater intrinsic complexity to be given to particles like electrons, etc. This leads to russian dolls and problem of infinite regress. Bohm writes:
In analogy to what has been said about human experiences, the particles constituting matter in general may be considered to represent a more gross (explicate) somatic level of activity, while the Schrodinger wave field corresponds to a finer, subtler, more implicate and 'mind-like' level. In human experience however, it has been proposed that each 'mind-like' level can be regarded as a somatic bearer of form when seen from a yet finer and more subtle level. This would imply firstly that the information represented by the Schrodinger wave field is being 'carried' by a finer and subtler level of matter that has not yet been revealed more directly. But even more important, it also implies that there may be a finer and more subtle level of information that guides the Schrodinger field, as the information on the Schrodinger field guides the particles. But this in turn is a yet more subtle 'somatic' form, which is acted on by a still more subtle kind of information, and so on. Such a hierarchy could in principle go on indefinitely. This means, of course, that the current quantum mechanical laws are only simplifications and abstractions from a vast totality, of which we are only 'scratching the surface'. That is to say, in physical experiments and observations carried out this far, deeper levels of this totality have not yet revealed themselves.
http://www.implicity.org/Downloads/Bohm_meaning+information.pdf
http://philsci-archive.pitt.edu/8345/1/dimensions.pdf
http://users.ox.ac.uk/~sfop0257/papers/Finding.pdf
http://courses.cit.cornell.edu/north/QM_for_volume.pdf
http://spot.colorado.edu/~monton/BradleyMonton/Articles_files/qm%203n%20d%20space%20final.pdf
http://vimeo.com/4607553 (Maudlin video-Can the world be only wave-function?)
1. David Albert:3N-dimensional space realism.
The space in which any realistic interpretation of quantum mechanics is necessarily going to depict the history of the world as playing itself out … is configuration-space. And whatever impression we have to the contrary (whatever impression we have, say, of living in a 3-dimensional space, or in a 4-dimensional space-time) is somehow flatly illusory...In reality, there is just a single 3N-dimensional wavefunction, and the division of reality into separate three-dimensional objects, including organisms, is just the product of our internal representation.
Problem: Why does the world appear 3-dimensional (or 4-dimensional if space-time) to us? What does N represent in 3N space (what is the space a configuration of, if not the particles)? (For Albert all that exists is a single particle, evolving one way or another in a very high-dimensional space). Maudlin finds this view hard to swallow because he finds it "obscure how something happening at a point (such as a particle occupying a point or a field being concentrated near a point) could be a complexly structured physical state of affairs...it is not easy to understand how those physical structures could constitute cats, or chairs, or people."
2. Monton/Lewis:3-dimensional space is fundamental. The 3N-dimensional space is an illusion/false as wave function is only a mathematical tool
While their arguments are somewhat different, both claim that the world really is 3-dimensional and the 3N-dimensional space is a kind of an illusion for different reasons. While Monton flatly rejects the reality of 3-N space ("the wave function is no more real than the numbers-such as 2 or p"), Lewis rules it out by arguing that the "dimensionality" of configuration space defining the wavefunction is not really "spatial". Both seem to deny the reality of the wave function.
Problem: Predictions of QM depend on the 3N-dimensional space that get lost in the 3-dimensional representation (e.g. information about correlations among different parts of the system, that are experimentally observed are left out).
3. T. Maudlin:3N-dimensional space is a mathematical tool but the wave function is "real" (in a unique way)
There are two distinct fundamental spaces (3-dimensional and 3N-dimensional), each with its own structure. What’s more, each space must possesses additional structure beyond what is normally attributed to it. Further structure is needed to ground the connections between the two fundamental spaces, saying which parts and dimensions of the high-dimensional space correspond to which parts and dimensions of ordinary space, and which axes of configuration space correspond to which particle.
Problem: Adds additional fundamental structure, making it less elegant/more complex.
Maudlin argues, that's fine, because such structure is needed to make an informationally complete description, from which "every physical fact about the situation can be recovered". With respect to the wavefunction structure, Maudlin doesn't make a commitment but suggests that it may be unlike anything else (sorta "physical"/real but in a unique/different way), kind of "in its own metaphysical category". He does appear (if I understand him and those that discuss his views) to regard configuration space as only a mathematical tool; however, he also regards the wave function as more than just a probability wave, even though we don't have direct access to it. This doesn't bother him as he writes: "If our only access to the wavefunction is via its effect on the particles, and if the connection to the lived world is primarily through the particles, then we are not constrained about the physical nature of the wavefunction."
4. Bohm:3N-dimensional space is a "real" information field represented in a "mind-like" entity represented by the wave function.
3-N space is an abstract multi-dimensional "informational space" that guides a particle evolving in 3-dimensional space.
Problem: How can an "informational field" guide the particle? How does it interact with it to inform it? The field acts on the particles but particle doesn't act on the field. Brown has argued that this goes against Einstein's action-reaction principle. Einstein wrote it is "contrary to the mode of scientific thinking...to conceive of a thing...which acts itself, but which cannot be acted upon."
Regardless this ontology requires far greater intrinsic complexity to be given to particles like electrons, etc. This leads to russian dolls and problem of infinite regress. Bohm writes:
In analogy to what has been said about human experiences, the particles constituting matter in general may be considered to represent a more gross (explicate) somatic level of activity, while the Schrodinger wave field corresponds to a finer, subtler, more implicate and 'mind-like' level. In human experience however, it has been proposed that each 'mind-like' level can be regarded as a somatic bearer of form when seen from a yet finer and more subtle level. This would imply firstly that the information represented by the Schrodinger wave field is being 'carried' by a finer and subtler level of matter that has not yet been revealed more directly. But even more important, it also implies that there may be a finer and more subtle level of information that guides the Schrodinger field, as the information on the Schrodinger field guides the particles. But this in turn is a yet more subtle 'somatic' form, which is acted on by a still more subtle kind of information, and so on. Such a hierarchy could in principle go on indefinitely. This means, of course, that the current quantum mechanical laws are only simplifications and abstractions from a vast totality, of which we are only 'scratching the surface'. That is to say, in physical experiments and observations carried out this far, deeper levels of this totality have not yet revealed themselves.
http://www.implicity.org/Downloads/Bohm_meaning+information.pdf
http://philsci-archive.pitt.edu/8345/1/dimensions.pdf
http://users.ox.ac.uk/~sfop0257/papers/Finding.pdf
http://courses.cit.cornell.edu/north/QM_for_volume.pdf
http://spot.colorado.edu/~monton/BradleyMonton/Articles_files/qm%203n%20d%20space%20final.pdf
http://vimeo.com/4607553 (Maudlin video-Can the world be only wave-function?)
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