On Mon, Jul 2, 2012 at 11:55 PM, meekerdb <meeke...@verizon.net> wrote:
> On 7/2/2012 6:15 PM, Jason Resch wrote: > > > > On Mon, Jul 2, 2012 at 5:35 PM, meekerdb <meeke...@verizon.net> wrote: > >> On 7/2/2012 2:09 PM, Jason Resch wrote: >> >>> >>> >>> To summarize our conversation up to this point: >>> >>> BM: Do you really not see any difference between tables and chairs and >>> people and numbers, >>> JR: Chairs and people are also mathematical objects, just really complex >>> ones with a large information content. This is the necessary conclusion of >>> anyone who believes physical laws are mathematical. >>> BM: No, it's a necessary conclusion of anyone who cannot distinguish a >>> description from the thing described. >>> JR: I think the identity of indiscernibles applies: If no distinction >>> can ever be made (by observers within a mathematical universe and observers >>> within a physical universe) then there is no distinction. You are using >>> "physical" as an honorific, but it adds no information. >>> BM: I can point to a chair and say "This!" >>> JR: Yes, but how do you know you are pointing to a "physical chair", >>> rather than a "mathematical chair"? >>> BM: I know I'm pointing at a chair. I don't know what at 'mathematical >>> chair' is. Can you point out how it is different from a chair? >>> >>> I think we both agree that if the universe follows mathematical laws, >>> then observers can make no distinction between whether they exist in a >>> platonically existing mathematical object, or a physical universe. If you >>> agree with this, then there is no fundamental ontological difference >>> between chairs, people, and numbers, that I can see. >>> >> >> No. The mathematical laws of physics (e.g. the standard model) leave >> initial conditions undetermined, > > > Which is equivalent to saying every solution to the Schrodinger equation > is true. > > > It's true that they are solutions. It doesn't follow that they exist. > We could take the position that they don't exist, but then we wouldn't be taking our own theories seriously. Defending collapse is like defending retrograde motion in order to cling to a stationary Earth hypothesis: we don't feel the earth moving, it is against our intuition, so why should we take seriously a theory that says it moves when we can instead take retrograde motion as true and have a theory that doesn't upset anyone? > > > > >> they assume inherent randomness (symmetry breaking), > > > No where in the math of quantum mechanics is there anything that suggest > collapse of the wave function. > > > Except that's the only way to get a definite result. Otherwise your > instruments say, "Well it was probably + and probably -." > They all happen, probability, like time is a phenomenon of observation. Let me ask you an unrelated question: Do you think quantum computers with thousands of qubits will one day be built, or do you think they are impossible to build, for one reason or another? If you think they will be built one day, the world will be forced to confront the issue of many universes head-on. How could a few atoms calculate what a universe-sized computer could not finish in the entire lifetime of the universe? > > > A strict interpretation of the the math leaves only MWI (or > alternatively, as Ron Garett points out zero-universes > https://www.youtube.com/watch?v=dEaecUuEqfc ). > > > How did you decide the Born rule wasn't math and wasn't part of QM? > > > What is your opinion of Deutsch et al.'s work in recovering the Born rule? https://en.wikipedia.org/wiki/Many-worlds_interpretation#Deutsch_et_al. Deutsch *et al.* An information-theoretic <https://en.wikipedia.org/wiki/Information_theory>derivation of the Born rule from Everettarian assumptions, was produced by David Deutsch <https://en.wikipedia.org/wiki/David_Deutsch> (1999)[30]<https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-29>and refined by Wallace (2002–2009) [31] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-30> [32] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-31> [33] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-32> [34] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-33>and Saunders (2004). [35] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-34> [36] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-35>Deutsch's derivation is a two-stage proof: first he shows that the number of orthonormal <https://en.wikipedia.org/wiki/Orthonormal_basis>Everett-worlds after a branching is proportional to the conventional probability density <https://en.wikipedia.org/wiki/Probability_density>. Then he uses game theory to show that these are all equally likely to be observed. The last step in particular has been criticised for circularity<https://en.wikipedia.org/wiki/Circular_definition> .[37]<https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-baker-36> [38] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-37>Other reviews have been positive, although the status of these arguments remains highly controversial; some theoretical physicists have taken them as supporting the case for parallel universes.[39]<https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-newsci-38> [40] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-39>In the New Scientist <https://en.wikipedia.org/wiki/New_Scientist> article, reviewing their presentation at a September 2007 conference,[41]<https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-40> [42] <https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-41>Andy Albrecht, a physicist at the University of California at Davis, is quoted as saying "This work will go down as one of the most important developments in the history of science."[39]<https://en.wikipedia.org/wiki/Many-worlds_interpretation#cite_note-newsci-38> > The randomness is explained directly by first person indeterminacy in a > reality containing all possibilities. > > > Maybe. But it's not clear that it explains the Born rule. > > > > >> they don't specify why they are the laws of physics instead of some >> others. > > > Many physicists hope that they will one day find a reason that our laws of > physics are unique, some justification why the one they find themselves in > is the only one that can be, but this seeming to be a pipe dream. Many > physicists dislike anthropic reasoning, perhaps because it spoils their > dream of finding a TOE, but disliking something shouldn't carry any weight > in assessing a theory's validity. > > > I could say the same about the Born rule and disliking that some things > happen and some don't. > > > > >> So the ontological difference is that some things exist and some don't. >> This distinction doesn't exist in Platonia: exist=having a consistent >> description. In physics exist=a member of the ontology of the fundamental >> model. >> > > What's wrong with Platonia being a fundamental model? > > > No predictive power: everything exists, everything happens. > > We have predictive power. Our physical theories still work (despite the goings on in other universes and places). Now we just have a meta-theory (where there was none before) that might explain the probability distribution of different types of universes, why we shouldn't be surprised at the appearance of fine tuning, why our universe can be viewed as a block time universe, why there is something rather than nothing, etc. > > > >> >> That's why Everett, to avoid having some randomness, postulated that we >> exist in many copies. > > > I think there are more reasons than that. Before Everett, QM was > extremely ugly, being the only non-local, non-time reversible, FTL > permitting, theory in all of physics. It is more accurate to say Bohr and > Heisenberg inserted collapse into the theory in an attempt to rescue the > single-universe idea. There is nothing in the math of QM to suggest > collapse exists, its addition was entirely artificial, and done to make the > theory seem to fit in with our experience. > > > What shameful reason! :-) > I don't think it was shameful, but in retrospect it is an obvious error. It would be like sticking retrograde motion in, under the mistaken belief that if the earth was moving, we would be able to feel it. Everett himself, explains it better than I can, in his letter to Bryce DeWitt: http://www.pbs.org/wgbh/nova/manyworlds/orig-02a.html With an explanation of why the theory itself explains why observers don't feel themselves split, or measure both results the motivation for inserting collapse entirely disappears. > > > Everett showed there was no need to do this to fit with our experience, > as the theory itself explains why we don't feel ourselves split. > > >> Others have postulated multiple copies of the universe beyond the Hubble >> radius or in separate inflating spacetimes. Tegmark proposed "all >> mathematical structures". Most of this strikes me as a metaphysical >> stretch to equate the physical world with the Platonic. > > > Why? > > > >> In Platonia everything not self-contradictory exists. There is no >> difference between logical and nomological. Our universe is 'explained' by >> anthropic selection from everything. > > > And yet another mystery: fine tuning, is explained away. > > >> So do you think there were chairs before there were people? Were there >> numbers before people? >> >> > There is no before or after in Platonia. Time is only meaningful to > observers inside certain mathematical structures. > > >> >> >>> Facing the question: is the universe a mathematical object, or a >>> physical one, we must evaluate the two candidate theories as we would any >>> other. >>> >> >> That's not the question. The question is whether all mathematical >> objects exist while only some physical ones do. > > > No. If all mathematical objects exist, then all things which could be > considered physical universes exist too. What possible difference is there > between a physical universe and a mathematical structure isomorphic to that > universe? Should these extraneous physical universes not be discarded > according to Occam? > > > Along with all the hypothetical ones in Platonia? > Occam is about the complexity of the theory, not the number of objects implied by the theory. For example, it was a simpler theory to suppose that the stars were distant suns (rather than some other kind of phenomenon), despite that it has implied the existence of trillions of other suns. The theory is simple, reality isn't. Actually, it seems the simpler the theory, the larger reality is. In Newton's view, a specification of the initial conditions and laws of physics uniquely defines the entire universe, but that description is a huge amount of information. Under QM, there is no need to specify the initial conditions, only the laws of this universe (and it is assumed all solutions to those laws correspond to valid universes). This is a much shorter description, but a much larger reality. Under mathematical realism, there is no specification of initial conditions or laws, and the reality implied by leaving the laws and initial conditions open is larger still. > > > > > >> In the latter case we need to find which physical ones exist and what is >> their mathematical description. >> >> >> Does one theory explain more, does one make fewer assumptions, etc. The >>> existence of the physical universe does not explain the existence of >>> mathematical objects >>> >> >> I think it does. See William S. Coopers "The Evolution of Reason". >> >> >> > "The formal systems of logic have ordinarily been regarded as independent > of biology, but recent developments in evolutionary theory suggest that > biology and logic may be intimately interrelated. In this book, William S. > Cooper outlines a theory of rationality in which logical law emerges as an > intrinsic aspect of evolutionary biology. He examines the connections > between logic and evolutionary biology and illustrates how logical rules > are derived directly from evolutionary principles, and therefore, have no > independent status of their own. This biological perspective on logic, > though at present unorthodox, could change traditional ideas about the > reasoning process." > > Perhaps rules of logic exist in biology, but the full set of truth > concerning the natural numbers is not contained in biology. > > > > > > >> , but the converse is true. >>> >> >> But only in the cheap sense of 'explain' like "God did it." Bruno at >> least limits his fundamental ontology to digital computation, but even this >> threatens to 'explain' too much. >> >> > It is more powerful than "God did it". Given sufficiently powerful > computers, we can verify predictions of the theory. > > > How. It predicts everything. > > Just because everything exists does not mean everything occurs the same number of times. If we assume things occur with different measures, this will enable us to test the theory. If we find that a universe(s) with laws like ours occurs very early in the trace of the UDA, that would perhaps go a long way toward verifying this theory. In another example, if we enumerate a large set of randomly compacted Calabi–Yau manifolds, to determine the probability distribution for different fundamental constants, and find that the constants of our universe fit very well within those distributions, that might also support such a theory. > > Tegmark also believes we can test his theory by seeing statistically how > well our universal constants fit within certain bounds necessary for life > to exist. > > > That faces two big problems. First, it requires some non-arbitrary > measure be defined on 'universes'. MML might work. Second, no matter what > the measure we know already that life exists here so finding it to be > improbable would prove nothing and neither would finding it probable - one > sample statistics aren't very informative. > You are right, they are not, but science has been forced to draw conclusions based on single samples before. For example, the statistic of how early life appeared on earth once conditions permitted it has led scientists to estimate that it is very probable that life emerges in similar environments. Jason -- You received this message because you are subscribed to the Google Groups "Everything List" 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.
