On 12/10/2012 5:41 AM, Jason Resch wrote:

On Mon, Dec 10, 2012 at 12:32 AM, meekerdb <meeke...@verizon.net<mailto:meeke...@verizon.net>> wrote:On 12/9/2012 5:03 PM, Jason Resch wrote:On Sun, Dec 9, 2012 at 6:51 PM, meekerdb <meeke...@verizon.net <mailto:meeke...@verizon.net>> wrote: On 12/9/2012 4:37 PM, Jason Resch wrote:On Sun, Dec 9, 2012 at 5:40 PM, meekerdb <meeke...@verizon.net <mailto:meeke...@verizon.net>> wrote: On 12/9/2012 12:08 PM, Jason Resch wrote:And without a doubt the most popular interpretation of Quantum Mechanics among working physicists is SUAC (Shut Up And Calculate), That's not an interpretation at all.Well for a more philosophical statement of it see Omnes. His view is that once you can explain the diagonalization of the the density matrix (either by eigenselection, dechoherence, or just assumed per Bohr) then you have predicted probabilities. QM is a probabilistic theory - so predicting probabilities is all you can ask of it. Is science just about its applications or about understanding the world? I would argue that science would not progress so far as it has if we thought finding the equation was the be all and end all of science. The "shut up and calculate" mindset can be translated as "don't ask embarrassing questions", it is the antithesis of scientific thinking. Student in the 1500s: Does the earth move about the sun, or do the planets merely appear to move as if earth moved about the sun? Professor in the 1500s: We have all the formulas for predicting planetary motion, so shut up and calculate! Fortunately, Copernicus wasn't satisfied with that answer.So what's your objection to Omnes? That the world just can't be probabilistic? So instead there must be infinitely many inaccessible worlds - which happen to mimic a probabilistic world. It is fine if QM is a probabilistic theory. Where I disagree with him is in his belief that we can never go beyond that in our understanding of it. I am not sure how accurate this statement is, since it is a secondary source, but http://en.wikipedia.org/wiki/Roland_Omn%C3%A8s says: "We will never, Omnès believes, find a common sense interpretation of quantum law itself." To me, it almost seems as if he says it is not worth trying to find an answer.Suppose he'd said in 1400CE, "We will never find a common sense interpretation of the sphericity of the Earth." He'd have been right; we didn't, instead we changed 'common sense'. I don't know, I think Sagan's explanation fits most people's common sense:http://www.youtube.com/watch?v=Jwr8CLX3NJA&t=1m19s<http://www.youtube.com/watch?v=Jwr8CLX3NJA&t=1m19s>I lean more towards David Deutsch who says science is about finding good explanations.But why isn't "It's a probabilistic world and it obeys the Born rule." a good explanation. It is worse than that. From: http://lesswrong.com/lw/q7/if_manyworlds_had_come_first/"All right," says Nohr. He sighs. "Look, if this theory of yours were actually true—ifwhole sections of the wavefunction just instantaneously vanished—it would be... let'ssee. The only law in all of quantum mechanics that is non-linear, non-unitary,non-differentiable and discontinuous. It would prevent physics from evolving locally,with each piece only looking at its immediate neighbors. Your 'collapse' would be theonly fundamental phenomenon in all of physics with a preferred basis and a preferredspace of simultaneity. Collapse would be the only phenomenon in all of physics thatviolates CPT symmetry, Liouville's Theorem, and Special Relativity. In your originalversion, collapse would also have been the only phenomenon in all of physics that wasinherently mental. Have I left anything out?"The page also asks:But suppose that decoherence and macroscopic decoherence had been realized immediatelyfollowing the discovery of entanglement, in the 1920s. And suppose that no one hadproposed collapse theories until 1957. Would decoherence now be steadily declining inpopularity, while collapse theories were slowly gaining steam?I'm all for finding a better explanation, i.e. a deterministic one. But simply postulating an ensemble of worlds to make the probabilities "deterministic" in arbitrary way doesn't strike me as any improvement.MWI follows directly from a literal reading of the equations, which contain no mentionof collapse or only applying only at certain scales.

`No it doesn't. It is no more than decoherence, which means that in a selected basis the`

`reduced density matrix becomes approximately diagonal. At that point Everett says the`

`different diagonal eigenvalues are the probabilities of projections onto orthogonal`

`subspaces, which being orthogonal can be regarded as different 'worlds'. But this suffers`

`the same problems as other interpretations (which is why Omnes says there isn't any`

`intuitive interpretation). First, there has to be a selection of a basis, which in an`

`experiment is made by a choice of instrument (what does your detector detect?). Whether`

`this is part of theory or a boundary condition depends on whether you include the`

`experimenter in the Hilbert space. But if you include the experimenter, you've just`

`backed out the boundary condition one step - you haven't eliminated it. Once the`

`instrument is modeled, then (in theory) you can calculate decoherence in the selected`

`basis and the *reduced* density matrix will become *approximately* diagonal in the`

`selected basis. But notice that there is nothing in the bare mathematics that tells you`

`the reduced density matrix gives you the probabilities. It is a choice based on the`

`instrument/environment division. The density matrix becomes (almost) diagonal when you`

`trace over the environment part (otherwise nothing has happened - or more precisely it`

`could unhappen). Performing this trace operation is a mathematical calculation, not part`

`of the physical evolution, and it philosophically equivalent to choosing a basis in which`

`to collapse a wave-function.`

Brent

Even better, the Born rule falls out as Everett himself noticed. If anyone isperforming a stretch (postulating new things), it is those in the collapse camp who addnew conjectures to the theory in an unjustified effort to preserve the notion of asingle universe. The theory itself explains why the other universes are not observed,so pretending we have to augment the theory by adding new postulates (observers,collapse, born rule) to make it agree with our observations is somewhat absurd.In the history of science efforts to keep humanity on the center stage seem to alwaysfail ( http://www.youtube.com/watch?v=o8GA2w-qrcg ). I think that very reason, to keepthe Earth near the "center of the universe", was and is the basis for collapse theories.Jason Brent "As to the fable that there are Antipodes, that is to say, men on the opposite side of the earth where the sun rises when it sets to us, men who walk with their feet opposite ours, that is on no ground credible. Even if some unknown landmass is there, and not just ocean, "there was only one pair of original ancestors, and it is inconceivable that such distant regions should have been peopled by Adam's descendants." --- St. Augustine --You received this message because you are subscribed to the Google Groups "EverythingList" group.To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en. No virus found in this message. Checked by AVG - www.avg.com <http://www.avg.com> Version: 2012.0.2221 / Virus Database: 2634/5448 - Release Date: 12/09/12

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