I don't think Newtonian physics is intuitive. Most people's intuition and experiences would not lead them to the idea that once set in motion an object continues to move forever, nor that the the total direction of matter is conserved. Even Descartes missed this.
Jason On Sun, May 24, 2015 at 8:27 PM, meekerdb <meeke...@verizon.net> wrote: > On 5/24/2015 5:05 AM, Pierz wrote: > > > > On Sunday, May 24, 2015 at 4:02:42 PM UTC+10, Brent wrote: >> >> On 5/23/2015 9:58 PM, Pierz wrote: >> >> >> >> On Saturday, May 23, 2015 at 8:36:40 PM UTC+10, Liz R wrote: >>> >>> I'm not sure why comp would predict that physical laws are invariant >>> for all observers. I can see that it would lead to a sort of >>> super-anthropic-selection effect, but surely all possible observers should >>> exist somewhere in arithmetic, including ones who observe different physics >>> (that is compatible with their existence) ? >>> >> >> I really must dig up the old thread! But I'm not saying comp does >> entail invariant physics for all observers, just that if there are >> different physics, the substitution level must be very low indeed. Think of >> the original scenario in the UDA: a person in Washington is suddenly >> annihilated, and then duplicated in Helsinki and Moscow (or whatever). That >> operation creates a 50% probability of finding oneself in Helsinki or >> Moscow. But the ultimate point of the UDA is that one's actual probability >> of finding oneself in Helsinki or Washington depends on the total measure >> of *all* virtual environments within which that observer is instantiated >> in an environment that looks like one of those cities. One can't isolate a >> particular virtual system from the trace of the UD. So you can't create an >> arbitrary physics in an environment that looks like either city (or >> anywhere). Well you can, but any observer will always find their own >> physics to be the measure of *all* their continuations in arithmetic. So >> there can't be an environment that is like Helsinki or Moscow at some point >> but that has different physical laws. Carry this logic over to the scenario >> of a person standing in an empty room - the physics the person experiences >> will be the measure of all such identical persons standing in empty rooms. >> >> >> "Experiencing physics" I think needs some explication. If experiencing >> only refers to consciously thinking propositions, then one may not be >> experiencing much physics: the world seems 3D with colors, there's a mild >> temperature, air smells OK,... One doesn't directly, consciously >> experience the 2nd law, or the Born rule. The "laws of physics" are human >> inventions to describe and predict events. They're not out there in >> Nature; which is why we have to revise them from time to time as we find >> more comprehensive, more accurate "laws". >> >> OK, but it doesn't seem relevant to the argument. We experience a world > predictable and stable in certain ways that, now we're so sophisticated, we > formalise into the science of physics. Bruno's claim is that these > regularities are not intrinsic properties of some primary stuff, but > emergent from the computational properties of observers - namely how often > various continuations of those observers crop up relatively to one another > in the abstract space of all possible continuations. I'm trying to make an > admittedly difficult point about whether or not observers in different > places can experience different physics within this paradigm, and if so, > how that relates to "substitution level". If you're worried about people > "experiencing physics" let's just concentrate on observers who go to the > trouble of doing physics experiments. It really doesn't matter. > > > My point was that most people's conscious experience most of the time > could be accommodated within a large range of physics. For example > Newtonian physics seems intuitive while quantum mechanics isn't; but we > think QM is the better theory. But Bruno claims that his theory implies QM > and not Newtonian mechanics. So if people consciously experienced a > Newtonian universe (which they once thought they did) would that falsify > comp or would it just imply that the UD can instantiate Newtonian universes. > > Brent > > > > >> The question here is what constitutes the observer? How detailed would >> a simulation of me have to be before it became a subjective *duplicate* of >> me, its continuations my continuations? If there is a person A somewhere in >> the UD who is experiencing an empty room with physics A, and another >> identically configured person B somewhere else experiencing physics B, what >> is stopping the continuations of A mixing with the continuations of B, so >> that the measures combine into a merged physics? There has to be something >> in both observers' computational states that distinguishes them >> sufficiently that their experiences cannot interfere with one another - the >> comp equivalent of decoherence. (In fact if QM effects are the >> manifestation of UD observer measures, the threshold at which these effects >> start to kick in should probably give us a strong clue about how low the >> substitution level is!) >> >> Observers and their experiences, including physical laws, can't be kept >> apart by physical or temporal space, but only by differences in the >> computational states that define them. Physics is emergent from the >> computational properties of observers, and therefore any difference in >> physics experienced by different observers is a function of their >> mathematical configuration. If we find that there are observers in other >> universes who experience different physics, then it must be the case that >> the substitution level for those observers includes their entire universe. >> >> That said, if I recall our previous discussion correctly, Bruno >> disfavoured the idea of different physics for different observers. He seems >> to believe it should indeed be invariant. >> >> That position appears to me to be at odds with the direction of modern >> cosmology. >> >> >> That would seem to depend on how different. Modern cosmology naturally >> builds on quantum field theory, so it starts with the hypothesis the QFT >> applies, but possibly with different values of those parameters we >> attribute to symmetry breaking (i.e. random). >> > > Yeah. I mean the ultimate underlying unity and coherence of reality is > surely a given, so go deep enough and of course there is only one law that > applies to all observers. But at issue is whether quite different apparent > physics (say, the elements and their properties, or the masses of > particles) is possible without the substitution level being super-duper > low. It seems to me not, and I believe Bruno agreed, though I may have > misunderstood. No-one seems to be addressing that question. > > >> Brent >> > -- > 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. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > -- > 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. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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