On Sun, Feb 27, 2022, 11:43 AM Tomas Pales <litewav...@gmail.com> wrote:
> On Thursday, February 24, 2022 at 4:45:11 AM UTC+1 meeke...@gmail.com > wrote: > >> This should be of interest to all the everythingists on this list. I'd >> especially like to hear what Bruno thinks of it. It's a bit expensive, so >> I may wait for more reviews before I take it up. >> >> *Birmingham-based philosopher Alastair Wilson has taken up the Herculean >> task of putting modal realism and many-worlds quantum theory together into >> a coherent, unitary view of reality. The results of this effort have been >> presented in several papers in recent years, and are now assembled in this >> thought-provoking book. While, as we will see, questions remain, Wilson has >> no doubt managed to come up with ingenious new hypotheses and has proposed >> solutions to existing problems and, more generally, with a powerful new >> modal realist view. The resulting perspective will certainly be of interest >> in the coming years, especially for naturalistically inclined philosophers, >> demanding that metaphysical hypotheses be made as continuous with our best >> science as possible.* >> >> >> https://ndpr.nd.edu/reviews/the-nature-of-contingency-quantum-physics-as-modal-realism/ >> >> From the review I take it that Wilson has missed the intermediate kind of >> possibility, namely computability which is between logical possibility and >> nomological possibility. >> >> Brent >> > > I am not sure what is new here. Many-worlds interpretation of QM is > obviously an example of Lewis' modal realism in the context of QM. As was > discussed here some time ago, it may not even involve splitting of worlds. > That is, all the quantum parallel worlds may be distinct worlds (objects) > even before a measurement; they are just exactly the same before the > measurement (exact copies of each other) and they start to differ at the > measurement event. A regularity in the multiverse of these quantum worlds > manifests in the fact that the worlds start differing in proportions given > by the Born rule, based on the (same) state of the worlds at the moment of > measurement. > > More generally about possible worlds or objects, I still see no difference > between a world that is logically possible (consistent) and a world that > "exists". A logically possible world is a world that is identical to > itself, that is, it has the properties it has and does not have the > properties it does not have. If two worlds have all the same properties > except the property of existence (one exists and the other doesn't) what > does it even mean? So I see no alternative to modal realism. > > If we want to go into more details we may ask what properties a world or > object may have and based on that we may differentiate between different > kinds of worlds or objects, for example spatiotemporal worlds versus worlds > that don't have a temporal or spatial structure. > There has been some work in this question which I cover some of here: https://alwaysasking.com/why-does-anything-exist/#Why_Time Also, there are also arguably anthropic reasons for our 3+1 spacetime: https://alwaysasking.com/is-the-universe-fine-tuned/#Infinitely_Intelligent_Babies_and_Spacetime_Dimensionality An important kind of property is relations between objects (relational > properties), and the most general kind of relation is similarity, which > holds between any two objects and thus is a necessary kind of relation. It > just means that two objects have certain common properties and certain > different properties. Mathematics as the most general study of relations > explores the similarity relation as morphism in category theory and has > reduced it to the set membership relation in set theory. Set theory is > interesting to me in that it grounds mathematics in concrete worlds made of > collections (sets), as opposed to abstract relations like numbers, > functions, symmetries etc. > > But if all mathematically (structurally) and consistently characterized > worlds/objects exist, it seems surprising that we live in a world with > quite stable laws of physics that persist in time (along the time dimension > of spacetime). > Even in an everything ensemble, observers should expect to find stable, simple, probabilistic laws: https://alwaysasking.com/why-does-anything-exist/#Why_Laws Since reality is a mess of everything possible we might expect that the > regularities (laws) of our world may change or disappear any second, which > apparently doesn't happen. > Or you don't remember it happening: "When we die, the rules surely change. As our brains and bodies cease to function in the normal way, it takes greater and greater contrivances and coincidences to explain continuing consciousness by their operation. We lose our ties to physical reality, but, in the space of all possible worlds, that cannot be the end. Our consciousness continues to exist in some of those, and we will always find ourselves in worlds where we exist and never in ones where we don’t. The nature of the next simplest world that can host us, after we abandon physical law, I cannot guess." -- Hans Moravec in “Simulation, Consciousness, Existence” (1998) https://frc.ri.cmu.edu/~hpm/project.archive/general.articles/1998/SimConEx.98.html Hume put it as "the constant conjunction between causes and effects." The > fact that the laws of physics in our world have been stable for billions of > years may be explained by the anthropic principle: we could have evolved > only in a world with such a long term stability. But it may not be obvious > why such a stability would continue into the future. In fact, it may seem > that such a stability in the future is very unlikely because there are many > ways our world could be in the future but only one way in which it would be > a deterministic extension of the world it has been until now. Maybe the > future stability can be explained by Solomonoff induction, which seems to > imply the opposite: it is more likely that laws of physics will continue to > hold. Why? Because *given the way our world has been until now*, this > world is more simple if its regularities (such as laws of physics) continue > than if they are discontinued, and more simple worlds are more likely (more > frequent in the collection of all possible worlds) than more complex > worlds. (A simpler set of properties is instantiated in more possible > worlds than a more complex set of properties.) Such a deterministic world > is fully defined by some initial conditions and laws of physics, while a > world whose regularity is discontinued at some point would need an > additional property that would define the discontinuation and thereby make > the world more complex. Solomonoff induction deals only with computable > sequences, I don't know if it can be generalized to uncomputable sequences. > If it can't, it may indicate that conscious beings of our kind can only > exist in a world with such a computable feature (or else we would likely > see the stability of laws of physics disappear any second from now). I > don't understand the mathematical details of Solomonoff induction and it > seems to be a rather unfamiliar explanation for why we should expect the > laws of physics to remain stable. > https://arbital.com/p/solomonoff_induction/ > > Yes this is the basis of Markus Mueller's work, deriving physical law from algorithmic information theory, which is based on Smolonoff induction. As Saibal Mitra (on this list) said: "To derive the effective laws of physics, one needs to do statistics over the ensemble of identical observers. This involves performing summations over the multiverse, but these summations are with a constraint that says that some given observer is present." -- Saibal Mitra <https://orcid.org/0000-0002-0396-9402> in *discussion list <https://groups.google.com/g/everything-list/c/lKZmqsADCPo/m/NUNgo02AAQAJ>* (2018) This of course means the laws are only approximately stable, and from the perspective of any observer may change, or be invented on the fly (e.g. when discovering ever less significant digits of some fundamental constant). It also means any theory bridging ultimate reality and physics needs some theory of observation (consciousness). Physics after all, is the science of observation: predicting future observations given past ones. Jason -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. 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