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Re: MWI

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  • Bruno Marchal
    ... No problem. Take your time. ... I don t know for David. With computationalism made explicit, the whole of the physical reality emerges from the first
    Message 1 of 62 , May 30, 2013
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      On 29 May 2013, at 22:43, hibbsa wrote:

      >
      >
      > --- In Fabric-of-Reality@yahoogroups.com, Bruno Marchal
      > <marchal@...> wrote:
      > >
      > > On 27 May 2013, at 16:33, hibbsa wrote:
      > >
      > > >
      > > >
      > > > --- In Fabric-of-Reality@yahoogroups.com, Bruno Marchal
      > > > <marchal@> wrote:
      > > > >
      > > > >
      > > > > On 27 May 2013, at 14:32, hibbsa 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?
      > > > > >
      > > > > > I mean "statistically significant" in the most rounded
      > possible sense.
      > > > > >
      > > > > > - Any difference that our universe couldn't have gone the
      > way of,
      > > > > > consistent with its initial conditions all laws of physics
      > assumed
      > > > > > constant
      > > > > >
      > > > > > - 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.
      > > > > >
      > > > > > - Any difference on any level at all where to be different
      > at the
      > > > > > bottom level requires contradicting the probabilistic rules
      > of QM
      > > > > > 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. And the philosophy is all about
      > intrepidly
      > > > > > working through the consequences?
      > > > > >
      > > > > > 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.
      > > > > >
      > > > >
      > > > > What do you mean by "exhibiting any statistically significant
      > > > > differences than our own universe? "
      > > > >
      > > > > If you prepare an electron in the up + down state, and if you
      > measure
      > > > > its up/down state, QM predicts that you will end up yourself
      > in the
      > > > > "seeing-up + seeing-down" state. If you had decided to go in
      > the North
      > > > > or in the south, according to the result of that measurement,
      > you end
      > > > > up in the visiting-North + visiting-South. from your points of
      > view
      > > > > that is statistically different, imo. You get two
      > macroscopically
      > > > > quite different lives. This with a probability 1/2, when
      > evaluated
      > > > > before the measurement, about your future first person points
      > of view.
      > > > >
      > > > > Now if your question is just "is there a macroscopic world in
      > which
      > > > > elephant can fly?", the answer is also "yes", but the
      > probability,
      > > > > here-and-now, that you will see such an elephant is equivalent
      > to
      > > > > winning the big lottery every second for a time much bigger
      > than the
      > > > > age of the universe, so don't count on it. Near death, that
      > question
      > > > > is just much more complex to get an answer today.
      > > > >
      > > > > The MWI is just the statement that the SWE applies to
      > everything,
      > > > > macrosocopic, mesoscopic, microscopic, etc.
      > > > >
      > > > > OK?
      > > > >
      > > > > Bruno
      > > > >
      > > >
      > > > Hi Bruno - no not OK but my fault. I meant statistically different
      > > > macroscopic universes. So you need to name your macroscopic
      > > > object...preferably with clear, known emergent properties. And
      > show
      > > > how those emergent properties are altered in any of its associated
      > > > quantum histories, from say,....the differences that would be
      > > > exhibited by enough copies of the object in this universe to
      > > > represent all the possible quantum histories.
      > > >
      > > > And if there aren't any differences...and if our macroscopic world
      > > > is emergent phenomena from the quantum state, then it's hard to
      > see
      > > > how the multiverse can exhibit statistically significant
      > differences
      > > > between its macroscopic universes.
      > > >
      > > I am still not sure I really grasp your question. 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.
      > >
      > > 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.
      > >
      > > 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,
      > >
      > > Bruno
      > >
      >
      > Sorry for the delay...I just wanted to think about your response for
      > a couple of days.
      >
      No problem. Take your time.



      >
      > One of the issues is that what I'm saying here about emergence and
      > emergent properties is very much based on David Deutsch's BoI book
      > and also his version of MWI.
      >
      > I'm not saying your points aren't valid or important....but would it
      > be possible for you to reference his Reality of Abstractions chapter
      > and then answer the question ,more generally in terms of emergent
      > properties as he defines them?
      >
      > The basic argument from me is that, since macroscopic reality is in
      > terms of emergence, for the multiverse to produce a significantly
      > different macroscopic world, it would have to change the emergent
      > properties.
      >
      I don't know for David. With computationalism made explicit, the whole
      of the physical reality emerges from the first person experience that
      you can associate to some infinities of arithmetical relations. The
      whole of physics is emergent, I think, from arithmetic or Turing
      equivalent. But that view from inside arithmetic is not Turing
      equivalent.



      >
      > I appreciate you've pointed to a Harry Potter world...but
      > surely...that world can also be understood in terms of something
      > that * might*, or *might have* happened in this world?
      >
      Yes, but with a very small relative probability, which is eventually
      determined by the axioms for the basic ontology (arithmetic or Turing
      equivalent). The view from inside is much more rich, and indeed
      arguably beyond the whole of mathematics.

      Bruno




      >
      >

      http://iridia.ulb.ac.be/~marchal/





      [Non-text portions of this message have been removed]
    • Brett Hall
      ... We are in complete agreement on that point. It is entirely possible for someone to say of course that is the case! with respect to everything you have
      Message 62 of 62 , Jun 4, 2013
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        On 05/06/2013, at 9:03 AM, "hibbsa" <hibbsa@...> wrote:

        >
        >
        > --- In Fabric-of-Reality@yahoogroups.com, Brett Hall <brhalluk@...> wrote:
        > >
        > > On 02/06/2013, at 6:17, "hibbsa" <hibbsa@...> wrote:
        > >
        > > >
        > > >
        > > > --- In Fabric-of-Reality@yahoogroups.com, Brett Hall <brhalluk@> wrote:
        > > > >
        > > > > On 30/05/2013, at 6:56, "hibbsa" <hibbsa@> wrote:
        > > > >
        > > > > >
        > > > > >
        > > > > > --- In Fabric-of-Reality@yahoogroups.com, Bruno Marchal <marchal@> wrote:
        > > > > > >
        > > > > > > On 27 May 2013, at 16:33, hibbsa wrote:
        > > > > > >
        > > > > > > >
        > > > > > > >
        > > > > > > > --- In Fabric-of-Reality@yahoogroups.com, Bruno Marchal
        > > > > > > > <marchal@> wrote:
        > > > > > > > >
        > > > > > > > >
        > > > > > > > > On 27 May 2013, at 14:32, hibbsa 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?
        > > > > > > > > >
        > > > > > > > > > I mean "statistically significant" in the most rounded possible sense.
        > > > > > > > > >
        > > > > > > > > > - Any difference that our universe couldn't have gone the way of,
        > > > > > > > > > consistent with its initial conditions all laws of physics assumed
        > > > > > > > > > constant
        > > > > > > > > >
        > > > > > > > > > - 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.
        > > > > > > > > >
        > > > > > > > > > - Any difference on any level at all where to be different at the
        > > > > > > > > > bottom level requires contradicting the probabilistic rules of QM
        > > > > > > > > > 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. And the philosophy is all about intrepidly
        > > > > > > > > > working through the consequences?
        > > > > > > > > >
        > > > > > > > > > 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.
        > > > > > > > > >
        > > > > > > > >
        > > > > > > > > What do you mean by "exhibiting any statistically significant
        > > > > > > > > differences than our own universe? "
        > > > > > > > >
        > > > > > > > > If you prepare an electron in the up + down state, and if you measure
        > > > > > > > > its up/down state, QM predicts that you will end up yourself in the
        > > > > > > > > "seeing-up + seeing-down" state. If you had decided to go in the North
        > > > > > > > > or in the south, according to the result of that measurement, you end
        > > > > > > > > up in the visiting-North + visiting-South. from your points of view
        > > > > > > > > that is statistically different, imo. You get two macroscopically
        > > > > > > > > quite different lives. This with a probability 1/2, when evaluated
        > > > > > > > > before the measurement, about your future first person points of view.
        > > > > > > > >
        > > > > > > > > Now if your question is just "is there a macroscopic world in which
        > > > > > > > > elephant can fly?", the answer is also "yes", but the probability,
        > > > > > > > > here-and-now, that you will see such an elephant is equivalent to
        > > > > > > > > winning the big lottery every second for a time much bigger than the
        > > > > > > > > age of the universe, so don't count on it. Near death, that question
        > > > > > > > > is just much more complex to get an answer today.
        > > > > > > > >
        > > > > > > > > The MWI is just the statement that the SWE applies to everything,
        > > > > > > > > macrosocopic, mesoscopic, microscopic, etc.
        > > > > > > > >
        > > > > > > > > OK?
        > > > > > > > >
        > > > > > > > > Bruno
        > > > > > > > >
        > > > > > > >
        > > > > > > > Hi Bruno - no not OK but my fault. I meant statistically different
        > > > > > > > macroscopic universes. So you need to name your macroscopic
        > > > > > > > object...preferably with clear, known emergent properties. And show
        > > > > > > > how those emergent properties are altered in any of its associated
        > > > > > > > quantum histories, from say,....the differences that would be
        > > > > > > > exhibited by enough copies of the object in this universe to
        > > > > > > > represent all the possible quantum histories.
        > > > > > > >
        > > > > > > > And if there aren't any differences...and if our macroscopic world
        > > > > > > > is emergent phenomena from the quantum state, then it's hard to see
        > > > > > > > how the multiverse can exhibit statistically significant differences
        > > > > > > > between its macroscopic universes.
        > > > > > > >
        > > > > > > I am still not sure I really grasp your question. 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.
        > > > > > >
        > > > > > > 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.
        > > > > > >
        > > > > > > 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,
        > > > > > >
        > > > > > > Bruno
        > > > > > >
        > > > > >
        > > > > > Sorry for the delay...I just wanted to think about your response for a couple of days.
        > > > > >
        > > > > > One of the issues is that what I'm saying here about emergence and emergent properties is very much based on David Deutsch's BoI book and also his version of MWI.
        > > > > >
        > > > > > I'm not saying your points aren't valid or important....but would it be possible for you to reference his Reality of Abstractions chapter and then answer the question ,more generally in terms of emergent properties as he defines them?
        > > > > >
        > > > >
        > > > > He states, on page one of that chapter, that emergent phenomena are a "tiny minority" of phenomena.
        > > >
        > > > What significance are you attaching to his point? Emergent properties arise out of huge complexity hence they are a tiny minority of phenoma.
        > > >
        > > > He also talks on page 5 of my kindle edition, about the arrow of time and the second law of thermodynamics. Disorder tends to increase. Energy is reduced in "quality" as time goes on. So although it is possible for water placed in a kettle to freeze...this is crazy unlikely. David explains on that page that it is unknown if the second law can be derived from lower level physics. The second law seems fundamental though.
        > > > >
        > > > > Will there be universes where the second law *does not hold*? No.
        > > > >
        > > > > There will be universes where it might seem not to hold...but they are Harry Potter universes again.
        > > >
        > > > I think your view is debatable, but I don't currently see the importance.
        > > >
        > > > >
        > > > > A universe where the second law did not hold would not be very interesting for long. What would happen would be that time would *appear* to go backwards. But that would just be appearances. It would just be that things would get more ordered as time went on. So stars and galaxies would become warm nebulae which would then collect together and, I guess either form some great solid mass or just spread out uniformly throughout space in some huge crystalline structure. It would be a boring universe. And at any instant, this order would be shattered, in complete accord with the laws.
        > > >
        > > > Or this universe could be the anomaly, and all that we regard as laws could actually be anti-laws - bizarelly unlikely reversals of acutal laws in a harry potter universe, which could be shattered at any moment.
        > > >
        > > > I mean, you don't know do you?
        > > >
        > >
        > > I do *know* because to *know* means I have a good explanation, not that I am certain. And the explanation I have is quantum theory which explains Harry Potter universes are the minority. Our 'stable' universes with predictable events is more typical.
        > >
        > > So yes, I know.
        > >
        > > To assert otherwise - that Harry Potter universes are typical, while ours is not, is to presume that we have completely misunderstood the Schrodinger Wave equation and what expectation values are.
        > > >
        > > > > >
        > > > > > The basic argument from me is that, since macroscopic reality is in terms of emergence, for the multiverse to produce a significantly different macroscopic world, it would have to change the emergent properties.
        > > > > >
        > > > > Yes, if what *you* mean by "properties" means "physical objects". If you mean "emergent laws" then no, even these would be the same.
        > > >
        > > > If by emergent laws you mean the statistical laws, like in thermodynamics. Then....I can't make sense of the distinction you are making. To the extent they arise from QM, the multiverse cannot create universes that are different. To the extent they arise from something other than QM, the multiverse cannot create universes that are different. So it's the same issue either way.
        > > >
        > > What do you mean "different"? There are many different universes in the multiverse...so I don't know what you mean. They all have the same laws but it's those same laws that ensure that there is differentiation.
        > >
        > > >
        > > >> Consider that if there was a universe where the internal combustion engine did not exist, the laws governing that engine still would. Likewise, a universe with no life would still have laws governing predator-prey relationships...they just would never be "instantiated" (so to speak).
        > > >>
        > > > This all seems to be reinforcing the point I'm making. The multiverse doesn't create universes that are different. The point I'm making is...I thought...uncontroversial so far as that goes. Deutsch already says it. But what I'm pointing out is the *extremity* of that sameness.
        > > >
        > >
        > > Still not sure what you mean by different. You say the multiverse doesn't create universes that are different - but that *is* precisely what it does do, unless I have some really fundamental misconception. Right now a different universes exists where a copy of me is not typing this post. It's different to the one I am in here now where I am typing away. And the multiverse "created" those different universes.
        > >
        > > >
        > > > > >
        > > > > > I appreciate you've pointed to a Harry Potter world...but surely...that world can also be understood in terms of something that * might*, or *might have* happened in this world?
        > > > > >
        > > > > Yes. That's exactly how we do understand such universes...as places where it is highly unlikely anything like that might (or might have) ever happened.
        > > > >
        > > >
        > > > And about that, my point so far is just that, the multiverse of a particular object, looks exactly the same as statistic model of what might happen in this universe. Shouldn't be a controversial point.
        > > >
        > > Well I don't understand it clearly enough to appreciate whether it would be controversial or not.
        > >
        > >
        > >
        > > > As I say...where I'm going with this I haven't got to yet. I just want to nail that we all agree on these points.
        > > >
        > >
        > > I don't know, in places, even what we are talking about to know if we agree. For example: what you are referring to by the word "different" as applied to universes above and saying the multiverse doesn't create (have? Generate?) different universes. But it does. So you must have something else in mind.
        > >
        > > I don't know what.
        > >
        > > Brett.
        > > >
        >
        > Brett - on my side I'm at risk of becoming confused as to what the issues are between us. Would you mind if I just restated my original question (not necessarily verbatim)?
        >
        > My question is whether MWI adherents agree that for a given multiverse divergence of a given 'object' from a given common ancestor world, the maximum divergence for the vast majority of histories will be governed by the first emergence of the first macroscopic 'emergent' properties?
        >
        > About the above...I would like to know...does this question make sense? If it kind-sorta makes sense, then that's a start...what do you (or anyone else) think it might most sensibly mean? Do you have an answer for that meaning?
        >
        > To reiterate. I don't think what I am suggesting (I.e an affirmative answer) is, or should be, controversial. I think Deutsch pretty much already says it is the case. I think it is a straight consequence of some hard aspects of MWI that it is the case.
        >
        > So from my perspective I think it should be possible for people to say something like "of course that is the case!"
        >
        >

        We are in complete agreement on that point. It is entirely possible for someone to say "of course that is the case!" with respect to everything you have written above.

        Brett.

        [Non-text portions of this message have been removed]
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