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Re: Fine- and coarse-grained histories

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  • pourrientui
    Speaking of Feynman integrals... In his QED, Feynman uses virtual photons in his description of partical interactions. Virtual sounds familiar, yes? Has
    Message 1 of 11 , Dec 1, 2002
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      Speaking of Feynman integrals...

      In his QED, Feynman uses "virtual photons" in his description of
      partical interactions.

      "Virtual" sounds familiar, yes?

      Has anyone re-interpreted QED using MWI?
    • Marchal Bruno
      ... This is an interesting question. I have had a discussion about it on this list with Saibal Mitra. We have not yet really conclude the discussion. The
      Message 2 of 11 , Dec 5, 2002
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        pourrientui <Pourrientui@...> wrote:

        >Speaking of Feynman integrals...
        >
        >In his QED, Feynman uses "virtual photons" in his description of
        >partical interactions.
        >
        >"Virtual" sounds familiar, yes?
        >
        >Has anyone re-interpreted QED using MWI?


        This is an interesting question. I have had a discussion
        about it on this list with Saibal Mitra. We have not yet
        really conclude the discussion. The question is reducible
        to the more general "how far should we take the QM formalism
        as describing reality?". Saibal believes "virtual" particles
        are just mathematical trick. I would take the theory more
        at face value, but then we need some MWI account of renorma-
        lisation. Not easy, and to my knowledge, this has not been
        analyzed in the literature. Any light on this is indeed
        welcome.

        Bruno
      • alan_forrester2
        ... of ... Yes, but it doesn t seem to be the same thing as parallel universes. Whenver you make a measurement you end up observing a particular universe (the
        Message 3 of 11 , Dec 5, 2002
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          --- In Fabric-of-Reality@y..., "pourrientui" <Pourrientui@a...>
          wrote:

          > Speaking of Feynman integrals...
          >
          > In his QED, Feynman uses "virtual photons" in his description
          of
          > partical interactions.
          >
          > "Virtual" sounds familiar, yes?
          >

          Yes, but it doesn't seem to be the same thing as parallel
          universes. Whenver you make a measurement you end up
          observing a particular universe (the one you end up in), but you
          never see virtual photons in any observations.

          > Has anyone re-interpreted QED using MWI?

          There is a paper on Quantum Field Theory and the MWI here but
          nothing specifically on QED of which I am aware.

          See

          http://xxx.lanl.gov/abs/quant-ph/0204024

          Alan
        • Tony Hollick
          ... From: Marchal Bruno To: Sent: Thursday, December 05, 2002 10:56 AM Subject: Re: Fine- and
          Message 4 of 11 , Dec 5, 2002
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            ----- Original Message -----
            From: "Marchal Bruno" <marchal@...>
            To: <Fabric-of-Reality@yahoogroups.com>
            Sent: Thursday, December 05, 2002 10:56 AM
            Subject: Re: Fine- and coarse-grained histories


            > pourrientui <Pourrientui@...> wrote:
            >
            > >Speaking of Feynman integrals...
            > >
            > >In his QED, Feynman uses "virtual photons" in his description of
            > >partical interactions.
            > >
            > >"Virtual" sounds familiar, yes?
            > >

            It should do. Feynman's "virtual photons" are "virtually" identical to
            Walter Ritz's "particles fictives" described in his [1908] paper on the
            ballistic theory of light. Einstein and Ritz knew each other -- they
            co-published a paper setting out their agreements and disagreements.

            Ritz's work provides an alternative explanation to Michelson-Morley.


            > >Has anyone re-interpreted QED using MWI?
            >

            Why should they? QED claims to provide a complete physical explanation
            of the world inone world, whereas MWI is a "rescue hypothesis" dreamed up by
            Everett as a "patch" for a problem in QM, which can never be a description
            and explanation of the real world.


            Basing an entire scientific world-view on a patch for a flawed formalism
            seems most unwise.


            >
            > This is an interesting question. I have had a discussion
            > about it on this list with Saibal Mitra. We have not yet
            > really conclude the discussion. The question is reducible
            > to the more general "how far should we take the QM formalism
            > as describing reality?". Saibal believes "virtual" particles
            > are just mathematical trick. I would take the theory more
            > at face value, but then we need some MWI account of renorma-
            > lisation. Not easy, and to my knowledge, this has not been
            > analyzed in the literature. Any light on this is indeed
            > welcome.
            >
            > Bruno
            >

            Not in all quarters, it doesn't. >:-}

            Tony Hollick

            >
            >
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
          • PaintedDevil@aol.com
            In a message dated 12/5/2002 5:58:57 PM GMT Standard Time, ... Maybe virtual photons exist in universes which are cancelled out by interference? Charles
            Message 5 of 11 , Dec 6, 2002
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              In a message dated 12/5/2002 5:58:57 PM GMT Standard Time,
              alan_forrester2@... writes:


              > Yes, but it doesn't seem to be the same thing as parallel
              > universes. Whenver you make a measurement you end up
              > observing a particular universe (the one you end up in), but you
              > never see virtual photons in any observations.

              Maybe virtual photons exist in universes which are cancelled out by
              interference?

              Charles


              [Non-text portions of this message have been removed]
            • Doug Gill
              ... To start the question, we could list what photon P and virtual photon vP share and don t share. The obvious is that they are both messenger particles. The
              Message 6 of 11 , Dec 6, 2002
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                Marchal Bruno wrote:

                > pourrientui <Pourrientui@...> wrote:
                >
                > >Has anyone re-interpreted QED using MWI?
                >
                >
                > This is an interesting question. I have had a discussion
                > about it on this list with Saibal Mitra. We have not yet
                > really conclude the discussion. The question is reducible
                > to the more general "how far should we take the QM formalism
                > as describing reality?". Saibal believes "virtual" particles
                > are just mathematical trick. I would take the theory more
                > at face value, but then we need some MWI account of renorma-
                > lisation. Not easy, and to my knowledge, this has not been
                > analyzed in the literature. Any light on this is indeed
                > welcome.
                >
                > Bruno
                >

                To start the question, we could list what photon P and virtual photon vP
                share and don't share.

                The obvious is that they are both messenger particles. The vP explains
                the Lamb shift and why electrons repel each other.
                http://teachers.web.cern.ch/teachers/archiv/HST2000/teaching/resource/lessons/interact/2_exch.htm

                ENERGY CONSIDERATIONS
                vP violates energy conservation. This is OK as long as vP remains at the
                quantum mechanical level. Thus, the creation of the photon must not be
                registered (observed) at the classical level.
                By contrast, if P is observed, it does not violate any energy
                conservation law - the wavefunction has just collapsed.

                If we observed single P to go through two slits (as it does across
                multiple universes), we would have violated the conservation of energy
                for our entire universe (two photons = twice the energy of each).

                EFFECTS IN TWO UNIVERSES
                Scenario A
                The virtual photon acts in our universe and it does not act in a second
                universe. Electrons would not repel in the second universe and the two
                universes would display paradoxical laws. I dont think David intended
                this to be the case for the multiverse interpretation. Perhaps someone
                could clarify this point. The problem (if laws are paradoxical) is that
                the very reason for the concept of MWI, in the first place, is to solve
                the problem of paradox (in EPR-type experiments).

                Scenario B
                Virtual photons exist and act in both universes. The laws of physics are
                common in both universes. Universes have split by observation of
                electrons repelling, but each universe still contains vP. This is
                paradoxical since the alternative universes should contain alternative
                states for the existence of vP.

                We have paradoxical results within and across each scenario. This only
                works if some mechanism of paradox applies. If a mechanism of paradox
                applies, then the scenarios are not paradoxical : )

                Have virtual photons landed us in deep water again? Specifically, the
                concept of the multiverse is intended to solve paradoxical EPR-type
                effects at the quantum mechanical and classical levels, but we still
                find a paradoxical structure.

                Doug Gill
              • Alan Forrester
                ... http://teachers.web.cern.ch/teachers/archiv/HST2000/teaching/resource/lessons/interact/2_exch.htm ... No. It is inappropriate to describe light going
                Message 7 of 11 , Dec 6, 2002
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                  --- Doug Gill <douggill@...> wrote:

                  > > >Has anyone re-interpreted QED using MWI?
                  > >
                  > >
                  > > This is an interesting question. I have had a discussion
                  > > about it on this list with Saibal Mitra. We have not yet
                  > > really conclude the discussion. The question is reducible
                  > > to the more general "how far should we take the QM formalism
                  > > as describing reality?". Saibal believes "virtual" particles
                  > > are just mathematical trick. I would take the theory more
                  > > at face value, but then we need some MWI account of renorma-
                  > > lisation. Not easy, and to my knowledge, this has not been
                  > > analyzed in the literature. Any light on this is indeed
                  > > welcome.
                  >
                  > To start the question, we could list what photon P and virtual photon vP
                  > share and don't share.
                  >
                  > The obvious is that they are both messenger particles. The vP explains
                  > the Lamb shift and why electrons repel each other.
                  >
                  http://teachers.web.cern.ch/teachers/archiv/HST2000/teaching/resource/lessons/interact/2_exch.htm
                  >
                  > ENERGY CONSIDERATIONS
                  > vP violates energy conservation. This is OK as long as vP remains at the
                  > quantum mechanical level. Thus, the creation of the photon must not be
                  > registered (observed) at the classical level.
                  > By contrast, if P is observed, it does not violate any energy
                  > conservation law - the wavefunction has just collapsed.
                  >
                  > If we observed single P to go through two slits (as it does across
                  > multiple universes), we would have violated the conservation of energy
                  > for our entire universe (two photons = twice the energy of each).
                  >

                  No. It is inappropriate to describe light going through an interference
                  experiment in terms of photons, it is instead part of a larger multiversal
                  object we could call a Photon. The photons are a description of something
                  that is emergent from a Photon, namely that the multiverse tends to
                  decohere in some circumstances in such a way that it there are things that
                  act approximately like point particles.

                  > EFFECTS IN TWO UNIVERSES
                  > Scenario A
                  > The virtual photon acts in our universe and it does not act in a second
                  > universe. Electrons would not repel in the second universe and the two
                  > universes would display paradoxical laws. I dont think David intended
                  > this to be the case for the multiverse interpretation. Perhaps someone
                  > could clarify this point. The problem (if laws are paradoxical) is that
                  > the very reason for the concept of MWI, in the first place, is to solve
                  > the problem of paradox (in EPR-type experiments).
                  >
                  > Scenario B
                  > Virtual photons exist and act in both universes. The laws of physics are
                  > common in both universes. Universes have split by observation of
                  > electrons repelling, but each universe still contains vP. This is
                  > paradoxical since the alternative universes should contain alternative
                  > states for the existence of vP.
                  >
                  > We have paradoxical results within and across each scenario. This only
                  > works if some mechanism of paradox applies. If a mechanism of paradox
                  > applies, then the scenarios are not paradoxical : )
                  >
                  > Have virtual photons landed us in deep water again? Specifically, the
                  > concept of the multiverse is intended to solve paradoxical EPR-type
                  > effects at the quantum mechanical and classical levels, but we still
                  > find a paradoxical structure.

                  The multiverse, i.e. - physical reality according to quantum theory,
                  sometimes acts approximately like a collection of parallel universes and
                  sometimes doesn't. Your 'paradox' assumes that the multiverse always acts
                  like a collection of parallel universes when it clearly doesn't - as
                  evidenced by interference experiments the universes interact with each
                  other.

                  See

                  http://xxx.lanl.gov/abs/quant-ph/0104033

                  and

                  http://xxx.lanl.gov/abs/quant-ph/0210204

                  Alan

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                • Doug Gill
                  ... From your statement, it appears to me that this multiverse Photon (responsible for the interference pattern) is considered a Universal Object that
                  Message 8 of 11 , Dec 7, 2002
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                    Alan Forrester wrote:

                    >
                    > No. It is inappropriate to describe light going through an interference
                    > experiment in terms of photons, it is instead part of a larger multiversal
                    > object we could call a Photon. The photons are a description of something
                    > that is emergent from a Photon, namely that the multiverse tends to
                    > decohere in some circumstances in such a way that it there are things that
                    > act approximately like point particles.

                    From your statement, it appears to me that this multiverse Photon
                    (responsible for the interference pattern) is considered a Universal
                    Object that interferes in most cases but can decompose and be partly
                    accounted for by display in a single point. Would it be equally
                    appropriate to state that the interference arises from internal
                    properties of the photon rather than external properties of a larger Photon?

                    It seems to me that an interference pattern observed in our universe is
                    an observable property of our universe not the Universal Property of
                    many universes.

                    > The multiverse, i.e. - physical reality according to quantum theory,
                    > sometimes acts approximately like a collection of parallel universes and
                    > sometimes doesn't. Your 'paradox' assumes that the multiverse always acts
                    > like a collection of parallel universes when it clearly doesn't - as
                    > evidenced by interference experiments the universes interact with each
                    > other.
                  • Gary Oberbrunner
                    ... IMHO, hat s like saying that observing the product of 4 and 5 is observing only a 20, not the combination of the 4 and the 5. Of course it s really both.
                    Message 9 of 11 , Dec 9, 2002
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                      Doug Gill wrote:
                      > It seems to me that an interference pattern observed in our universe is
                      > an observable property of our universe not the Universal Property of
                      > many universes.

                      IMHO, hat's like saying that observing the product of 4 and 5 is
                      observing only a 20, not the combination of the 4 and the 5. Of course
                      it's really both. The 20 is just the visible tip of the iceberg.

                      -- Gary
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