Re: MWI

On 27/05/2013, at 22:55, "hibbsa" <hibbsa-/[email protected]> wrote:

> Does this question an answer?
> 
> Is it logically possible for the multiverse to produce macroscopic universes exhibiting any statistically significant differences than our own universe? 
> 



Some universes will be "Harry Potter" universes where, for example, the entire Pacific Ocean suddenly evapourates away into outer space. These are of vanishingly small measure. But that strange occurrence, although rare is pretty "significant". You need to explain what you mean by "statistically significant" because...

> 
> I mean "statistically significant" in the most rounded possible sense.
> 

There is no "most rounded possible sense". The term is most typically associated with how confident one is with probability values in terms of the *standard deviation*. You can learn more here:  http://en.wikipedia.org/wiki/Statistical_significance and then ask some questions or perhaps decide if using this term while chatting to Bruno (who is a mathematician and, while I do not wish to speak for him, presumably likes precision) is the best choice. Bruno, or me, or David - who have all now engaged with you on this might be thinking one thing about "statistically significant" while you are thinking something else entirely.


> 
> - Any difference that our universe couldn't have gone the way of, consistent with its initial conditions all laws of physics assumed constant
> 
> 



The multiverse prescribes exactly that. We answered that before. Different universes will evolve differently as a consequence of the very laws explaining their existence. Those laws holding in exactly the same way in all universes.



> - Any difference in terms of any phenomena existing at any level of abstraction in greater or lesser or with any difference in any attribute including (a) abundance (b) probability of occurrence (c) relation with other phenomena (d) internal constituents. 
> 

I do not understand all that. It's too much all at once for me. So...my fault then, perhaps.


> 
> - Any difference on any level at all where to be different at the bottom level requires contradicting the probabilistic rules of QM
> 

That won't happen. Why should it? Unless you have a better theory, then why should we guess that some times in some places the laws of QM are "contradicted". To assume that *is* a contradiction if we are talking science.


> and/or causing unique consequences of those rules as a result of interaction with macroscopic phenomena and at the top level requires any significant difference in the timing, macroscopic and microscopic structure, and ultimate fate of the universe. 
> 
> The reason I think this question deserves a proper full answer. And by that I mean...not just a criticism of the way the question is formed is because there could be important consequences...which may not be worked through.
> 



That is a bizarre condition actually bordering on the dogmatic/insulting. As if to say answers provided *so far* have not been "proper full". But we have tried! There's no reason to imply, with that line, that you are not being taken seriously or being given something less than "proper full" answers. 

So far you'e had myself, David Deutsch and now Bruno Marchal each independently ask you what you mean in various places. This is the best, most courteous, truth seeking way of proceeding. As I have conceded in another post on this exact topic - you may indeed have something here. I just don't know. No need for you to imply that so far I (for one) haven't given a full proper answer. I'm doing my best.

So to say stuff like your question "deserves a proper full answer" is quite something given you will not do the same for anyone else. Namely, you won't simply answer our question "What do you mean by that?" When you say (quote):


> Is it logically possible for the multiverse to produce macroscopic universes exhibiting any statistically significant differences than our own universe? 
> 



You have to understand that...we don't understand. We are not criticising *you* the person. We just want to understand the question. I thought I had a really good go at this. I thought David also responded to this in a very clear way. And now so too has Bruno. But it seems you are not happy with our responses and instead of asking further questions, or trying to rephrase, we get instructions to not provide



>  a criticism of the way the question is formed is because there could be important consequences
> 


But that "criticism" of the way the question is formed is the only way we can get to what you are actually talking about. Clearly you do need to change the *form* because all present attempts have failed. There can never be perfect transmission of a message so that receipt is error-free. All is fallible. In this case both you (the sender) and us (the receiver) are prone to errors. We just are not communicating well at all now so I'm asking for some error correction in the form of a re-transmission but in a different form because the current form seems to be error prone (whether it's with sender or receiver or both, I don't know - so this asking for rephrasing is one tactic I'm employing).

I might seem a little exasperated because I really thought the last series of postings on this topic did indeed make progress. That stuff about boiling water in kettles. The answer was a decisive "yes" - what happens to lots of identical things in this universe is going to be the same as what happens to lots of copies of the object in *other* universes. Bruno is more patient than I, clearly! But I think his most recent post deserves careful consideration by you. In line with what David and I said previously to you, Bruno has now also said:



> I am still not sure I really grasp your question.



I think that's fair. But it's *not* fair to say he should not be able to say this sort of thing (it *is* a criticism of form until we can get at the substance).




> Planck constant is 
> very little. So if you decide to boil some water, QM predicts that it 
> will boil normally in most of the branches you can access in the 
> multiverse, with some non negligible probability. Then you will have 
> the many universes fluctuating from that behavior, but, 
> proportionally, they will be rarer. At the extremal point of the 
> spectrum of the possibilities, you will have the "Harry Potter" 
> universe, but those are quasi-impossible to access (a good thing), 
> except perhaps near death, as the probabilities on the first person 
> expectancies get harder to compute.



I agree with all this. And it is what I was saying using the example of the cans of your water - some small measure of which boil instantly and some not at all (they are your Harry Potter universes).




> 
> Our macroscopic world is not emergent from the multiverse, except for 
> most quantum properties, so our universe is quantum normal, with 
> solid, liquid and gaz well described by the quantum statistics. but 
> each branches differ on orthogonal or quasi orthogonal state, and so 
> can differ in macroscopic properties (like if earth was not hit by an 
> asteroid a long time ago), but such branches will still obeys the same 
> macroscopic laws, like classical mechanics, for example.



Yes, the same laws exist in all places in the multiverse.




> 
> Our local realities are Gaussian, and that's why we can discern all 
> sort of laws. In fact that appears with just computationalism too. 
> Below our level of substitution, we emerge from infinities of 
> computations, which interfere statiostically, but above that level, we 
> have much simpler classical laws. In QM this is explained by MWI + 
> decoherence. With digital mechanism it is far more complex, but then 
> we can explain where the quantum comes from.
> 
> I hope this help, feel free to make your question more precise, if I 
> miss your point,



I am an optimist that hibbsa will!




> And the philosophy is all about intrepidly working through the consequences? 


But, hibbsa, how can we work through the consequences when we do not even understand the antecedents (the conditions, the thought experiment, the *question*?).


> 
> I've got some consequences waiting for your criticism. But I think it's important to establish your criticism or acceptance of the above first. 
> 



I am still asking "criticism or acceptance *of what*?". Again, we *can* reach consensus. We just have to keep trying. But asking the same question, without rephrasing, is not trying (not trying something new anyways) and that's no way to make progress...or come to some meeting of minds.



Brett.





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