The Fabric of Reality List: The work of David Deutsch is a Public Group with 1001 members.
 The Fabric of Reality List: The work of David Deutsch

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Re: Fine and coarsegrained histories
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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 reinterpreted QED using MWI?  pourrientui <Pourrientui@...> wrote:
>Speaking of Feynman integrals...
This is an interesting question. I have had a discussion
>
>In his QED, Feynman uses "virtual photons" in his description of
>partical interactions.
>
>"Virtual" sounds familiar, yes?
>
>Has anyone reinterpreted QED using MWI?
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   In FabricofReality@y..., "pourrientui" <Pourrientui@a...>
wrote:
> Speaking of Feynman integrals...
of
>
> In his QED, Feynman uses "virtual photons" in his description
> partical interactions.
Yes, but it doesn't seem to be the same thing as parallel
>
> "Virtual" sounds familiar, yes?
>
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 reinterpreted 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/quantph/0204024
Alan  Original Message 
From: "Marchal Bruno" <marchal@...>
To: <FabricofReality@yahoogroups.com>
Sent: Thursday, December 05, 2002 10:56 AM
Subject: Re: Fine and coarsegrained 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
copublished a paper setting out their agreements and disagreements.
Ritz's work provides an alternative explanation to MichelsonMorley.
> >Has anyone reinterpreted 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 worldview 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/
>
> 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
Maybe virtual photons exist in universes which are cancelled out by
> 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.
interference?
Charles
[Nontext portions of this message have been removed]  Marchal Bruno wrote:
> pourrientui <Pourrientui@...> wrote:
To start the question, we could list what photon P and virtual photon vP
>
> >Has anyone reinterpreted 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
>
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 EPRtype 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 EPRtype
effects at the quantum mechanical and classical levels, but we still
find a paradoxical structure.
Doug Gill   Doug Gill <douggill@...> wrote:
> > >Has anyone reinterpreted QED using MWI?
http://teachers.web.cern.ch/teachers/archiv/HST2000/teaching/resource/lessons/interact/2_exch.htm
> >
> >
> > 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.
>
>
No. It is inappropriate to describe light going through an interference
> 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).
>
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
The multiverse, i.e.  physical reality according to quantum theory,
> 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 EPRtype 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 EPRtype
> effects at the quantum mechanical and classical levels, but we still
> find a paradoxical structure.
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/quantph/0104033
and
http://xxx.lanl.gov/abs/quantph/0210204
Alan
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http://uk.my.yahoo.com  Alan Forrester wrote:
>
From your statement, it appears to me that this multiverse Photon
> 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.
(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.  Doug Gill wrote:
> It seems to me that an interference pattern observed in our universe is
IMHO, hat's like saying that observing the product of 4 and 5 is
> an observable property of our universe not the Universal Property of
> many universes.
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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