(MWI); quantum logic ~ John Baez ? [Archive]

Charlie Stromeyer Jr.

Jun3-04, 04:16 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n(Charles J. Quarra) wrote in message news:\n\n> this is important, since MWI is the only interpretation that makes\n> EPR a local action (without spooky action at a distance or hidden\n> variables), so in this sense, is elegant\n\nThere is a problem, though, because MWI, the Copenhagen\ninterpretation, John Cramer\'s transactional interpretation, Bohmian\nmechanics, etc. seem to have all been ruled out of existence three\nyears ago by this experiment:\n\nhttp://arxiv.org/abs/quant-ph/0102109\n\nNote that the inherent uncertainty here is clearly non-statistical or\nnon-probabilistic by any conventional probability theory, and so we\ncan perhaps interpret this bizarre finding as one definition of the\nnotion of "acausality".\n\nPerhaps someone like John Baez knows of a weird type of fuzzy or\nquantum logic that might be compatible with this experimental result.\nIf someone does have an idea about such an unusual logic then it might\nalso be interesting to see if this weird logic would somehow be\nrelated to what John Baez has written before about the relationship\nbetween quantum logic and non-associative mathematics.\n\nIf at first an idea does not seem crazy enough to be true then we\nshould scratch out the inside of whatever remains of our minds so that\nwe can start anew from scratch.\n\nSee, this is the kind of weird logic I\'m talking about !-)\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>(Charles J. Quarra) wrote in message news:

> this is important, since MWI is the only interpretation that makes
> EPR a local action (without spooky action at a distance or hidden
> variables), so in this sense, is elegant

There is a problem, though, because MWI, the Copenhagen
interpretation, John Cramer's transactional interpretation, Bohmian
mechanics, etc. seem to have all been ruled out of existence three
years ago by this experiment:

http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109

Note that the inherent uncertainty here is clearly non-statistical or
non-probabilistic by any conventional probability theory, and so we
can perhaps interpret this bizarre finding as one definition of the
notion of "acausality".

Perhaps someone like John Baez knows of a weird type of fuzzy or
quantum logic that might be compatible with this experimental result.
If someone does have an idea about such an unusual logic then it might
also be interesting to see if this weird logic would somehow be
related to what John Baez has written before about the relationship
between quantum logic and non-associative mathematics.

If at first an idea does not seem crazy enough to be true then we
should scratch out the inside of whatever remains of our minds so that
we can start anew from scratch.

See, this is the kind of weird logic I'm talking about !-)

Arkadiusz Jadczyk

Jun3-04, 07:56 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nOn 3 Jun 2004 05:16:49 -0400, cstromey@hotmail.com (Charlie Stromeyer\nJr.) wrote:\n\n>\n>There is a problem, though, because MWI, the Copenhagen\n>interpretation, John Cramer\'s transactional interpretation, Bohmian\n>mechanics, etc. seem to have all been ruled out of existence three\n>years ago by this experiment:\n>\n>http://arxiv.org/abs/quant-ph/0102109\n\nPhotons, perhaps, should be treated as relativistic. There is no\nsequentiality in EEQT, and there is even less sequentiality in\nrelativistic EEQT - see\n\nhttp://www.cassiopaea.org/quantum_future/papers/garda.htm\n\nfor a review.\n\nTo understand that sequentiality is not needed, notice that "interaction\nfree experiments" are easily understood within EEQT, and they are easily\nmodeled. The very presence of detectors changes the evolution of the\nwave function, whether they detect anything or not. Then, the wave\nfunction may pass through the detector, without triggering it, it\nchanges its shape, it can then trigger some other detector. All depends\non details, detector characteristics, wave function shapes etc.\n\nA typical effect, when there is a seeming "faster than light\ncommunication" in quantum tunneling is when a wave function passes\nthrough the initial detector, before the barrier, gets detected by the\nsecond detector, after the barrier, gets reflected, and then triggers\nthe first detector. It looks as "superluminal". But is simply out of\nsequence, due to reflections.\n\nark\n\n\n\n\n--\n\nArkadiusz Jadczyk\nhttp://www.cassiopaea.org/quantum_future/homepage.htm\n\n--\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>On 3 Jun 2004 05:16:49 -0400, cstromey@hotmail.com (Charlie Stromeyer
Jr.) wrote:

>
>There is a problem, though, because MWI, the Copenhagen
>interpretation, John Cramer's transactional interpretation, Bohmian
>mechanics, etc. seem to have all been ruled out of existence three
>years ago by this experiment:
>
>http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109

Photons, perhaps, should be treated as relativistic. There is no
sequentiality in EEQT, and there is even less sequentiality in
relativistic EEQT - see

http://www.cassiopaea.org/quantum_future/papers/garda.htm

for a review.

To understand that sequentiality is not needed, notice that "interaction
free experiments" are easily understood within EEQT, and they are easily
modeled. The very presence of detectors changes the evolution of the
wave function, whether they detect anything or not. Then, the wave
function may pass through the detector, without triggering it, it
changes its shape, it can then trigger some other detector. All depends
on details, detector characteristics, wave function shapes etc.

A typical effect, when there is a seeming "faster than light
communication" in quantum tunneling is when a wave function passes
through the initial detector, before the barrier, gets detected by the
second detector, after the barrier, gets reflected, and then triggers
the first detector. It looks as "superluminal". But is simply out of
sequence, due to reflections.

ark

--

Arkadiusz Jadczyk
http://www.cassiopaea.org/quantum_future/homepage.htm

--

Mike Stay

Jun4-04, 07:52 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\ncstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.c om>...\n> (Charles J. Quarra) wrote in message news:\n>\n> > this is important, since MWI is the only interpretation that makes\n> > EPR a local action (without spooky action at a distance or hidden\n> > variables), so in this sense, is elegant\n>\n> There is a problem, though, because MWI, the Copenhagen\n> interpretation, John Cramer\'s transactional interpretation, Bohmian\n> mechanics, etc. seem to have all been ruled out of existence three\n> years ago by this experiment:\n>\n> http://arxiv.org/abs/quant-ph/0102109\n\nThe experiment described there fits just fine within MWI. Why do you\nbelieve it rules anything out?\n\n\n[Moderator\'s note: In general different _intepretations_ of quantum mechanics\ntend to be indistinguishable by experiment, otherwise they would be different\ntheories, not different ways to talk about the same theory. -usc]\n\n\n--\nMike\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.com>...
> (Charles J. Quarra) wrote in message news:
>
> > this is important, since MWI is the only interpretation that makes
> > EPR a local action (without spooky action at a distance or hidden
> > variables), so in this sense, is elegant
>
> There is a problem, though, because MWI, the Copenhagen
> interpretation, John Cramer's transactional interpretation, Bohmian
> mechanics, etc. seem to have all been ruled out of existence three
> years ago by this experiment:
>
> http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109

The experiment described there fits just fine within MWI. Why do you
believe it rules anything out?

[Moderator's note: In general different _intepretations_ of quantum mechanics
tend to be indistinguishable by experiment, otherwise they would be different
theories, not different ways to talk about the same theory. -usc]

--
Mike

Oliver Jennrich

Jun4-04, 02:49 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>* Charlie Stromeyer, writes:\n\n> (Charles J. Quarra) wrote in message news:\n\n>> this is important, since MWI is the only interpretation that makes\n>> EPR a local action (without spooky action at a distance or hidden\n>> variables), so in this sense, is elegant\n\n> There is a problem, though, because MWI, the Copenhagen\n> interpretation, John Cramer\'s transactional interpretation, Bohmian\n> mechanics, etc. seem to have all been ruled out of existence three\n> years ago by this experiment:\n\n> http://arxiv.org/abs/quant-ph/0102109\n\nThe problem with this paper, though, is that it doesn\'t describe a\nreal experiment, much less presents any measurements, data, anything,\nthat is likely to show the postulated effects.\n\nWhat\'s worse, passages like\n\n| Nevertheless, the photon has not\n| been [permanently] absorbed by the atom, so no interaction between\n| the photon and the atom seems to have taken place.\n\nmakes me wonder if the authors really think that an absorption with a\nre-emission can be considered as "no interaction".\n\n--\nSpace - the final frontier\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Charlie Stromeyer, writes:

> (Charles J. Quarra) wrote in message news:

>> this is important, since MWI is the only interpretation that makes
>> EPR a local action (without spooky action at a distance or hidden
>> variables), so in this sense, is elegant

> There is a problem, though, because MWI, the Copenhagen
> interpretation, John Cramer's transactional interpretation, Bohmian
> mechanics, etc. seem to have all been ruled out of existence three
> years ago by this experiment:

> http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109

The problem with this paper, though, is that it doesn't describe a
real experiment, much less presents any measurements, data, anything,
that is likely to show the postulated effects.

What's worse, passages like

| Nevertheless, the photon has not
| been [permanently] absorbed by the atom, so no interaction between
| the photon and the atom seems to have taken place.

makes me wonder if the authors really think that an absorption with a
re-emission can be considered as "no interaction".

--
Space - the final frontier

Alan Forrester

Jun4-04, 02:50 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.c om>...\n\n> > this is important, since MWI is the only interpretation that makes\n> > EPR a local action (without spooky action at a distance or hidden\n> > variables), so in this sense, is elegant\n>\n> There is a problem, though, because MWI, the Copenhagen\n> interpretation, John Cramer\'s transactional interpretation, Bohmian\n> mechanics, etc. seem to have all been ruled out of existence three\n> years ago by this experiment:\n>\n> http://arxiv.org/abs/quant-ph/0102109\n>\n> Note that the inherent uncertainty here is clearly non-statistical or\n> non-probabilistic by any conventional probability theory, and so we\n> can perhaps interpret this bizarre finding as one definition of the\n> notion of "acausality".\n>\n> Perhaps someone like John Baez knows of a weird type of fuzzy or\n> quantum logic that might be compatible with this experimental result.\n> If someone does have an idea about such an unusual logic then it might\n> also be interesting to see if this weird logic would somehow be\n> related to what John Baez has written before about the relationship\n> between quantum logic and non-associative mathematics.\n\nI don\'t see any problem under the MWI. Let\'s recap the experiment. You\nhave an MZ interferometer with three atoms in one arm arm 1 and none\nin the other.\n\nLet the state of a photon in Arm 1 be written |1> and the state of a\nphton in the other arm be |2>. Let the state of atom j with spin Z+ be\n|Z+(j)>. Let the state of the atoms and photon at time t be |pa(t)>.\nWe trace the evolution of this state without assuming collapse as per\nthe MWI.\n\nNow, as I understand it, an atom with Z+ spin absorbs a photon and one\nin Z- does not, I shall assume that no other interactions take place.\nLet all three atoms be in a superposed state of Z+ and Z- with equal\nreal amplitude at the start of the experiment. We send the photon\nthrough a beamsplitter and a suitable phase shifter so that it is in a\nsimilar state wrt which arm it is in, i.e. - equal superposition with\nreal amplitudes. We will dub this time t=0 and so we have\n\n|pa(0)> = a(|1> + |2>)(|Z+(1)> + |Z-(1)>)(|Z+(2)> + |Z-(2)>)(|Z+(3)> +\n|Z-(3)>)\n\nwith a = 1/2sqrt(2)\n\nNow the photon comes to the first atom. If the atom has spin Z+ and\nthe photon is in branch 1 (of the interferometer) then the atom goes\noff. We will denote this state by |bangj> for atom j. Otherwise the\nphoton continues on its merry way as does the atom. We dub this t = 1\nSo we have\n\n|pa(1)> = a(|bang1> + |1>|Z-(1)> + |2>|Z+(1)> + |2>|Z-(1)>)(|Z+(2)> +\n|Z-(2)>)(|Z+(3)> + |Z-(3)>)\n\nSo the photon in the |1> arm is present in two versions after the\ninteraction, one of which keeps going while the other does not because\nit has been absorbed by atom 1. Now, if the photon has been absorbed\nby atom 1 then obviously it can\'t interact with atom 2 or 3. This\ninteraction and so the generation of these two versions is perfectly\nlocal, as can be seen from the fact that nothing has happened to atoms\n2 or 3 yet, or to the |2> version of the photon.\n\nLet |S(j)> = (|Z+(3)> + |Z-(3)>) just for notational convenience since\nthe terms will soon become complicated otherwise. Another local\ninteraction between |1> and atom 2 produces\n\n|pa(2)> = a(|bang1>|S(2)> + |S(1)>|bang2> + |1>|Z-(1)>|Z-(2)>\n+ |2>|S(1)>|S(2)>) |S(3)>\n\nIt\'s fairly obvious what the state at time t = 3 after the interaction\nwith atom 3 will be\n\n|pa(3)> = a(|bang1>|S(2)>|S(3)> + |S(1)>|bang2>|S(3)>\n+|S(1)>|S(2)>|bang3>\n+ |1>|Z-(1)>|Z-(2)>|Z-(3)> + |2>|S(1)>|S(2)>|S(3)>)\n\nI shall assume that at the end of the experiment we measure the Z spin\nof the atom and position of the photon in a destructive way so that\nthey decohere. Presumably by putting CCDs in both arms so that the\nphoton will reach them at t = 4 and destructively measuring the Z spin\nof atoms at t = 4 regardless of the outcome of the experiment. This\nwould prevent interference between the different terms.\n\nAfter each experiment there will be 1 world in which atom 1 interacted\nwith the photon, another in which atoms 2 did so and another in which\natom 3 did so. In none of these worlds will we see two atoms go off.\nThen there will be the world in which the photon didn\'t interact with\nany of the atoms despite being in the first branch of the\ninterferometer. Finally, there are 8 branches with the photon in the\nsecond arm, one for each possible measuring result on the atom. To\ncompare the readings on all the detectors we have to bring the\nrelevant information together.\n\nIf you really want to you can confirm that the six detectors (one CCD\nto detect photons for each arm of the interferometer gives 2, one for\neach atom adds three and then we need to bring the information from\nthese five together to a sixth detector) exhibit the appropriate\ncorrelations. Bear in mind that you can\'t carelessly cross out terms\nas in the article you referenced above and there won\'t be a problem.\n\nYou might want to read my contribution to the thread on the MWI, which\nhas good references.\n\nAlan\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.com>...

> > this is important, since MWI is the only interpretation that makes
> > EPR a local action (without spooky action at a distance or hidden
> > variables), so in this sense, is elegant
>
> There is a problem, though, because MWI, the Copenhagen
> interpretation, John Cramer's transactional interpretation, Bohmian
> mechanics, etc. seem to have all been ruled out of existence three
> years ago by this experiment:
>
> http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109
>
> Note that the inherent uncertainty here is clearly non-statistical or
> non-probabilistic by any conventional probability theory, and so we
> can perhaps interpret this bizarre finding as one definition of the
> notion of "acausality".
>
> Perhaps someone like John Baez knows of a weird type of fuzzy or
> quantum logic that might be compatible with this experimental result.
> If someone does have an idea about such an unusual logic then it might
> also be interesting to see if this weird logic would somehow be
> related to what John Baez has written before about the relationship
> between quantum logic and non-associative mathematics.

I don't see any problem under the MWI. Let's recap the experiment. You
have an MZ interferometer with three atoms in one arm arm 1 and none
in the other.

Let the state of a photon in Arm 1 be written |1> and the state of a
phton in the other arm be |2>. Let the state of atom j with spin Z+ be
|Z+(j)>. Let the state of the atoms and photon at time t be |pa(t)>.
We trace the evolution of this state without assuming collapse as per
the MWI.

Now, as I understand it, an atom with Z+ spin absorbs a photon and one
in Z- does not, I shall assume that no other interactions take place.
Let all three atoms be in a superposed state of Z+ and Z- with equal
real amplitude at the start of the experiment. We send the photon
through a beamsplitter and a suitable phase shifter so that it is in a
similar state wrt which arm it is in, i.e. - equal superposition with
real amplitudes. We will dub this time t=0 and so we have

|pa(0)> = a(|1> + |2>)(|Z+(1)> + |Z-(1)>)(|Z+(2)> + |Z-(2)>)(|Z+(3)> +|Z-(3)>)

with a = 1/2sqrt(2)

Now the photon comes to the first atom. If the atom has spin Z+ and
the photon is in branch 1 (of the interferometer) then the atom goes
off. We will denote this state by |bangj> for atom j. Otherwise the
photon continues on its merry way as does the atom. We dub this t = 1
So we have

|pa(1)> = a(|bang1> + |1>|Z-(1)> + |2>|Z+(1)> + |2>|Z-(1)>)(|Z+(2)> +|Z-(2)>)(|Z+(3)> + |Z-(3)>)

So the photon in the |1> arm is present in two versions after the
interaction, one of which keeps going while the other does not because
it has been absorbed by atom 1. Now, if the photon has been absorbed
by atom 1 then obviously it can't interact with atom 2 or 3. This
interaction and so the generation of these two versions is perfectly
local, as can be seen from the fact that nothing has happened to atoms
2 or 3 yet, or to the |2> version of the photon.

Let |S(j)> = (|Z+(3)> + |Z-(3)>) just for notational convenience since
the terms will soon become complicated otherwise. Another local
interaction between |1> and atom 2 produces

|pa(2)> = a(|bang1>|S(2)> + |S(1)>|bang2> + |1>|Z-(1)>|Z-(2)>+ |2>|S(1)>|S(2)>) |S(3)>

It's fairly obvious what the state at time t = 3 after the interaction
with atom 3 will be

|pa(3)> = a(|bang1>|S(2)>|S(3)> + |S(1)>|bang2>|S(3)>
+|S(1)>|S(2)>|bang3>+ |1>|Z-(1)>|Z-(2)>|Z-(3)> + |2>|S(1)>|S(2)>|S(3)>)

I shall assume that at the end of the experiment we measure the Z spin
of the atom and position of the photon in a destructive way so that
they decohere. Presumably by putting CCDs in both arms so that the
photon will reach them at t = 4 and destructively measuring the Z spin
of atoms at t = 4 regardless of the outcome of the experiment. This
would prevent interference between the different terms.

After each experiment there will be 1 world in which atom 1 interacted
with the photon, another in which atoms 2 did so and another in which
atom 3 did so. In none of these worlds will we see two atoms go off.
Then there will be the world in which the photon didn't interact with
any of the atoms despite being in the first branch of the
interferometer. Finally, there are 8 branches with the photon in the
second arm, one for each possible measuring result on the atom. To
compare the readings on all the detectors we have to bring the
relevant information together.

If you really want to you can confirm that the six detectors (one CCD
to detect photons for each arm of the interferometer gives 2, one for
each atom adds three and then we need to bring the information from
these five together to a sixth detector) exhibit the appropriate
correlations. Bear in mind that you can't carelessly cross out terms
as in the article you referenced above and there won't be a problem.

You might want to read my contribution to the thread on the MWI, which
has good references.

Alan

Tony Smith

Jun4-04, 02:50 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.c om>...\n> ... MWI, the Copenhagen\n> interpretation, John Cramer\'s transactional interpretation, Bohmian\n> mechanics, etc. seem to have all been ruled out of existence three\n> years ago by this experiment:\n> http://arxiv.org/abs/quant-ph/0102109\n\nThe paper cited by Charlie Stromeyer Jr. (Zirkus) was written\nby Elitzur and Dolev who in a subsequent paper at\nhttp://xxx.lanl.gov/abs/quant-ph/0207029\nseem to me to state that the general approach of the transactional\ninterpretation is not ruled out if it is interpreted as affecting\n"... not only events but also entire histories ...".\nPerhaps such a history (as opposed to mere event) interpretation\ncould also validate MWI, Bohm, etc.\n\nHere are some excerpts from\nhttp://xxx.lanl.gov/abs/quant-ph/0207029\nby Elitzur and Dolev:\n"... the results ... demonstrated an even more intriguing effect. ...\nif the photon indicates that interference was disrupted,\nthen, with 100% certainty, one of the atoms has "collapsed"\ninto the intersecting box.\nHowever, it can be any of the N atoms, not necessarily the first.\nWorse, once we have measured one of the atoms\nand found it in the intersecting box,\nall the other atoms return to their original,\nundisrupted, superposition state.\nConsequently,\nif we do not measure these atoms\' positions\nbut reunite the boxes and perform an "interference" measurement,\nthe atoms will always exhibit full interference,\nas if no photon has ever interacted with them!\n.... If one assumes that the photon\'s wave function has interacted\nwith the particular atom we\'ve measured so as to ruin its interference,\nhow come that all the other atoms in the row, positioned before and after\nthat particular atom, seem to have never been affected?\n....\nAnother offence to the ordinary temporal notions comes from our\n.... inverse EPR experiment ... In 44% (e.g., 4/9 ) of the cases\n.... one of the atoms will be subjected to z measurement ... while\nthe other atom will be subjected to x or y ...\nSuppose, then, that the first atom was found in the intersecting box.\nThis means that no photon has ever crossed that path.\nBut then, by Bell\'s proof, the other atom is still affected nonlocally\nby the measurement of the first atom.\nBut then again, if no photon has interacted with the first atom ... the\ntwo atoms share no causal connection, in either past of future!\n.... this experiment yields a history that is not consistent:\nOne atom indicates that the photon has taken only one path,\nwhile the other atom\'s state proves that both atoms have been visited\nby the same photon.\n....\nthe still unexplained CP violation exhibited by neutral kaons,\nwhich, by CPT invariance, entails a fundamental violation of T.\nConsequently, if a subtle time-asymmetry is inherent to physical\ninteractions themselves, the orthodox picture of time as a mere\ndimension looses much of its conviction.\n....\nthe "transactional" interpretations ... by invoking retarded-plus-\nadvanced actions, offer a simple and elegant explanation for many\nspatial and temporal peculiarities manifested by QM. ...\nwe ... propos[e]... that this spacetime is not static.\nPerhaps it, too, is subject to some subtle dynamics,\nthat is changes affect not only events but also entire histories.\nThen,\ntime\'s asymmetry will be anchored in that dynamics governing\nspacetime itself ...\nAlso, quantum mechanical experiments yielding apparently inconsistent\nhistories, as those described above, would give rise to an account like\n"first a retarded interaction brings about history t1x1, t2x2, ...\nand then\nan advanced interaction transforms this history into t1x\'1, t2x\'2, ...."\nSuch a model will be better capable of explaining quantum peculiarities\nof the kind described above, as well as a few other surprising results\ndiscovered lately by similar techniques ...".\n\nI should note that, although Elitzur and Dolev describe CP violation\nas "still unexplained", that phenomenon might be explainable by the\ncomplex phase of Kobayashi-Maskawa parameters - see for example\nhttp://www.physicstoday.org/pt/vol-54/iss-5/p17.html\n\nTony Smith\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.com>...
> ... MWI, the Copenhagen
> interpretation, John Cramer's transactional interpretation, Bohmian
> mechanics, etc. seem to have all been ruled out of existence three
> years ago by this experiment:
> http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109

The paper cited by Charlie Stromeyer Jr. (Zirkus) was written
by Elitzur and Dolev who in a subsequent paper at
http://xxx.lanl.gov/abs/http://www.arxiv.org/abs/quant-ph/0207029
seem to me to state that the general approach of the transactional
interpretation is not ruled out if it is interpreted as affecting
"... not only events but also entire histories ...".
Perhaps such a history (as opposed to mere event) interpretation
could also validate MWI, Bohm, etc.

Here are some excerpts from
http://xxx.lanl.gov/abs/http://www.arxiv.org/abs/quant-ph/0207029
by Elitzur and Dolev:
"... the results ... demonstrated an even more intriguing effect. ...
if the photon indicates that interference was disrupted,
then, with 100% certainty, one of the atoms has "collapsed"
into the intersecting box.
However, it can be any of the N atoms, not necessarily the first.
Worse, once we have measured one of the atoms
and found it in the intersecting box,
all the other atoms return to their original,
undisrupted, superposition state.
Consequently,
if we do not measure these atoms' positions
but reunite the boxes and perform an "interference" measurement,
the atoms will always exhibit full interference,
as if no photon has ever interacted with them!
.... If one assumes that the photon's wave function has interacted
with the particular atom we've measured so as to ruin its interference,
how come that all the other atoms in the row, positioned before and after
that particular atom, seem to have never been affected?
....
Another offence to the ordinary temporal notions comes from our
.... inverse EPR experiment ... In 44% (e.g., 4/9 ) of the cases
.... one of the atoms will be subjected to z measurement ... while
the other atom will be subjected to x or y ...
Suppose, then, that the first atom was found in the intersecting box.
This means that no photon has ever crossed that path.
But then, by Bell's proof, the other atom is still affected nonlocally
by the measurement of the first atom.
But then again, if no photon has interacted with the first atom ... the
two atoms share no causal connection, in either past of future!
.... this experiment yields a history that is not consistent:
One atom indicates that the photon has taken only one path,
while the other atom's state proves that both atoms have been visited
by the same photon.
....
the still unexplained CP violation exhibited by neutral kaons,
which, by CPT invariance, entails a fundamental violation of T.
Consequently, if a subtle time-asymmetry is inherent to physical
interactions themselves, the orthodox picture of time as a mere
dimension looses much of its conviction.
....
the "transactional" interpretations ... by invoking retarded-plus-
advanced actions, offer a simple and elegant explanation for many
spatial and temporal peculiarities manifested by QM. ...
we ... propos[e]... that this spacetime is not static.
Perhaps it, too, is subject to some subtle dynamics,
that is changes affect not only events but also entire histories.
Then,
time's asymmetry will be anchored in that dynamics governing
spacetime itself ...
Also, quantum mechanical experiments yielding apparently inconsistent
histories, as those described above, would give rise to an account like
"first a retarded interaction brings about history t1x1, t2x2, ...
and then
an advanced interaction transforms this history into t1x'1, t2x'2, ...."
Such a model will be better capable of explaining quantum peculiarities
of the kind described above, as well as a few other surprising results
discovered lately by similar techniques ...".

I should note that, although Elitzur and Dolev describe CP violation
as "still unexplained", that phenomenon might be explainable by the
complex phase of Kobayashi-Maskawa parameters - see for example
http://www.physicstoday.org/pt/vol-54/iss-5/p17.html

Tony Smith

Daryl McCullough

Jun4-04, 02:50 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>I\'d like to respond, not to Mike Stay, but to the moderator\'s\ncomment.\n\n>[Moderator\'s note: In general different _intepretations_ of quantum mechanics\n>tend to be indistinguishable by experiment, otherwise they would be different\n>theories, not different ways to talk about the same theory. -usc]\n\nIt isn\'t that clear-cut. The problem is that every theory has a few\nloose ends---details that are not completely spelled out by the theory.\nDifferent interpretations may fill in these details differently. In\nthe case of quantum mechanics, the unitary evolution of the wavefunction\nis pretty uncontroversial---every interpretation of quantum mechanics\nmust give equivalent results. On the other hand, exactly what happens\nwhen a measurement is made is difficult to get a firm grasp of, and different\ninterpretations of quantum mechanics fill in these details in different\nways. I suppose you could call the VonNeumann assumption that measurement\ncollapses the wave function a different theory than the MWI assumption that\nthe wave function never collapses, but I think most people would say that\nthese are different interpretations of the same theory.\n\n--\nDaryl McCullough\nIthaca, NY\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>I'd like to respond, not to Mike Stay, but to the moderator's
comment.

>[Moderator's note: In general different _intepretations_ of quantum mechanics
>tend to be indistinguishable by experiment, otherwise they would be different
>theories, not different ways to talk about the same theory. -usc]

It isn't that clear-cut. The problem is that every theory has a few
loose ends---details that are not completely spelled out by the theory.
Different interpretations may fill in these details differently. In
the case of quantum mechanics, the unitary evolution of the wavefunction
is pretty uncontroversial---every interpretation of quantum mechanics
must give equivalent results. On the other hand, exactly what happens
when a measurement is made is difficult to get a firm grasp of, and different
interpretations of quantum mechanics fill in these details in different
ways. I suppose you could call the VonNeumann assumption that measurement
collapses the wave function a different theory than the MWI assumption that
the wave function never collapses, but I think most people would say that
these are different interpretations of the same theory.

--
Daryl McCullough
Ithaca, NY

Italo Vecchi

Jun4-04, 02:50 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>staym@datawest.net (Mike Stay) wrote in message news:<d6255a14.0406040112.48c20a99@posting.google. com>...\n\n> > http://arxiv.org/abs/quant-ph/0102109\n>\n> The experiment described there fits just fine within MWI. Why do you\n> believe it rules anything out?\n>\n>\n> [Moderator\'s note: In general different _intepretations_ of quantum mechanics\n> tend to be indistinguishable by experiment, otherwise they would be different\n> theories, not different ways to talk about the same theory. -usc]\n\n\nBy the way, afaiu, what\'s described in\nhttp://arxiv.org/abs/quant-ph/0102109 is a thought experiment. It\nhasn\'t been actually carried out.\n\nIV\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>staym@datawest.net (Mike Stay) wrote in message news:<d6255a14.0406040112.48c20a99@posting.google.com>...

> > http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109
>
> The experiment described there fits just fine within MWI. Why do you
> believe it rules anything out?
>
>
> [Moderator's note: In general different _intepretations_ of quantum mechanics
> tend to be indistinguishable by experiment, otherwise they would be different
> theories, not different ways to talk about the same theory. -usc]

By the way, afaiu, what's described in
http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109 is a thought experiment. It
hasn't been actually carried out.

IV

Charlie Stromeyer Jr.

Jun6-04, 04:26 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>smi123th@innerx.com (Tony Smith) wrote in message news:\n\n> The paper cited by Charlie Stromeyer Jr. (Zirkus) was written\n> by Elitzur and Dolev who in a subsequent paper at\n> http://xxx.lanl.gov/abs/quant-ph/0207029\n> seem to me to state that the general approach of the transactional\n> interpretation is not ruled out if it is interpreted as affecting\n> "... not only events but also entire histories ...".\n\nTony, many thanks for mentioning this paper which I myself had not\nbothered to check for. It will take me some time to think about the\nquestions raised in this thread because there is a variety of related\nliterature that I should look at first.\n\nFor now, I will mention that the views within the above paper such as\nthe ideas of an emergent and intrinsic time arrow, the lack of\ndependence upon initial conditions, that time asymmetry is inherent\nfor all physical processes rather than an artefact of boundary\nconditions etc. are similar to the ideas of Stephen Wolfram (and maybe\nEd Fredkin and others) as you can see e.g. with the NKS book and\nperhaps also within some of the academic papers recently posted in the\n"Bibliography" section:\n\nhttp://www.wolframscience.com/reference/\n\n(Btw, I earlier took the pseudonym "zirkus" from Monty Python\'s\nFleigender Zirkus and from the book title "Fleigender Zirkus der\nPhysique")\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>smi123th@innerx.com (Tony Smith) wrote in message news:

> The paper cited by Charlie Stromeyer Jr. (Zirkus) was written
> by Elitzur and Dolev who in a subsequent paper at
> http://xxx.lanl.gov/abs/http://www.arxiv.org/abs/quant-ph/0207029
> seem to me to state that the general approach of the transactional
> interpretation is not ruled out if it is interpreted as affecting
> "... not only events but also entire histories ...".

Tony, many thanks for mentioning this paper which I myself had not
bothered to check for. It will take me some time to think about the
questions raised in this thread because there is a variety of related
literature that I should look at first.

For now, I will mention that the views within the above paper such as
the ideas of an emergent and intrinsic time arrow, the lack of
dependence upon initial conditions, that time asymmetry is inherent
for all physical processes rather than an artefact of boundary
conditions etc. are similar to the ideas of Stephen Wolfram (and maybe
Ed Fredkin and others) as you can see e.g. with the NKS book and
perhaps also within some of the academic papers recently posted in the
"Bibliography" section:

http://www.wolframscience.com/reference/

(Btw, I earlier took the pseudonym "zirkus" from Monty Python's
Fleigender Zirkus and from the book title "Fleigender Zirkus der
Physique")

scerir

Jun7-04, 04:54 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n"Daryl McCullough"\n> The problem is that every theory has a few\n> loose ends---details that are not completely\n> spelled out by the theory. Different interpretations\n> may fill in these details differently.\n\nEPR wrote that "if, without in any way disturbing\na system, we can predict with certainty (i.e. with\nprobability equal to unity) the value of a physical\nquantity, then there exists an element of physical\nreality corresponding to this physical quantity."\nNotice that they use the term "predict", which is\ndifferent, of course, from conditional probabilities.\nNow the question seems to be: is the above condition\n("realism") fulfilled by one of those many interpretations\nof QM? What about - paradoxically - the MWI?\ns.\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Daryl McCullough"
> The problem is that every theory has a few
> loose ends---details that are not completely
> spelled out by the theory. Different interpretations
> may fill in these details differently.

EPR wrote that "if, without in any way disturbing
a system, we can predict with certainty (i.e. with
probability equal to unity) the value of a physical
quantity, then there exists an element of physical
reality corresponding to this physical quantity."
Notice that they use the term "predict", which is
different, of course, from conditional probabilities.
Now the question seems to be: is the above condition
("realism") fulfilled by one of those many interpretations
of QM? What about - paradoxically - the MWI?
s.

backdoorstudent

Jun7-04, 04:54 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nstaym@datawest.net (Mike Stay) wrote in message news:<d6255a14.0406040112.48c20a99@posting.google. com>...\n> cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.c om>...\n> > (Charles J. Quarra) wrote in message news:\n> > http://arxiv.org/abs/quant-ph/0102109\n>\n> The experiment described there fits just fine within MWI. Why do you\n> believe it rules anything out?\n>\n>\n> [Moderator\'s note: In general different _intepretations_ of quantum mechanics\n> tend to be indistinguishable by experiment, otherwise they would be different\n> theories, not different ways to talk about the same theory. -usc]\n\nThis is not entirely correct. There are different interpretations\n(theories) of quantum mechanics that are in principle physically\ndistinguishible. For example, the deBroglie-Bohm (and other stochastic\ntheories based on a quantum potential) and the\nGhirardi-Rimini-Weber-Pearle spontaneous localization interpretations\ndiffer from standard quantum theory in specific instances. Indeed,\ntheir proponents actually call them "theories". As the technology\nprogresses experiments are expected to actually test these ideas.\n\nSorry to diverge from the topic a little here, but I think the terms\n"interpretation" and "theory" have become hideously blurred in quantum\nmechanics. Even the people who claim to use QM without interpretation\ntend to sneak in assumptions unconsciously. And in my opinion, it has\nbecome too dogmatic and fashionable to accuse those who want a\nconceptually coherent quantum theory of being "classically\npredjudiced" or practising metaphysics.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>staym@datawest.net (Mike Stay) wrote in message news:<d6255a14.0406040112.48c20a99@posting.google.com>...
> cstromey@hotmail.com (Charlie Stromeyer Jr.) wrote in message news:<61773ed7.0406022125.4cf6e44@posting.google.com>...
> > (Charles J. Quarra) wrote in message news:
> > http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109
>
> The experiment described there fits just fine within MWI. Why do you
> believe it rules anything out?
>
>
> [Moderator's note: In general different _intepretations_ of quantum mechanics
> tend to be indistinguishable by experiment, otherwise they would be different
> theories, not different ways to talk about the same theory. -usc]

This is not entirely correct. There are different interpretations
(theories) of quantum mechanics that are in principle physically
distinguishible. For example, the deBroglie-Bohm (and other stochastic
theories based on a quantum potential) and the
Ghirardi-Rimini-Weber-Pearle spontaneous localization interpretations
differ from standard quantum theory in specific instances. Indeed,
their proponents actually call them "theories". As the technology
progresses experiments are expected to actually test these ideas.

Sorry to diverge from the topic a little here, but I think the terms
"interpretation" and "theory" have become hideously blurred in quantum
mechanics. Even the people who claim to use QM without interpretation
tend to sneak in assumptions unconsciously. And in my opinion, it has
become too dogmatic and fashionable to accuse those who want a
conceptually coherent quantum theory of being "classically
predjudiced" or practising metaphysics.

Charlie Stromeyer Jr.

Jun7-04, 12:36 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:\n\n> > http://arxiv.org/abs/quant-ph/0102109\n>\n> The problem with this paper, though, is that it doesn\'t describe a\n> real experiment, much less presents any measurements, data, anything,\n> that is likely to show the postulated effects.\n\nNeither Newton nor Einstein themselves did actual experiments to\nmeasure the effects of gravity but this did not prevent their ideas\nfrom being correct!\n\nEither the above paper is mathematically valid within the formalism of\nquantum theory or it is not. So far, I do not see a flaw in the paper,\nbut this issue will take me some time to think about. Of course, there\nremains the possibilty if such an experiment were actually performed\nthat there would be some new effect introduced which I am currently\nnot intuiting, e.g. superconductivity was discovered by accident and\nnuclear fission would have been discovered by accident in 1935 by\nEmilio Segre if a piece of metal like tinfoil had not been blocking\nthe tell-tale signal.\n\n> What\'s worse, passages like\n>\n> | Nevertheless, the photon has not\n> | been [permanently] absorbed by the atom, so no interaction between\n> | the photon and the atom seems to have taken place.\n>\n> makes me wonder if the authors really think that an absorption with a\n> re-emission can be considered as "no interaction".\n\nAh, but this is why it is called "interaction free measurement" (IFM),\nand the authors are not discussing here what they might think per se,\nbut are instead discussing work done a decade previously by L. Hardy.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:

> > http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109
>
> The problem with this paper, though, is that it doesn't describe a
> real experiment, much less presents any measurements, data, anything,
> that is likely to show the postulated effects.

Neither Newton nor Einstein themselves did actual experiments to
measure the effects of gravity but this did not prevent their ideas
from being correct!

Either the above paper is mathematically valid within the formalism of
quantum theory or it is not. So far, I do not see a flaw in the paper,
but this issue will take me some time to think about. Of course, there
remains the possibilty if such an experiment were actually performed
that there would be some new effect introduced which I am currently
not intuiting, e.g. superconductivity was discovered by accident and
nuclear fission would have been discovered by accident in 1935 by
Emilio Segre if a piece of metal like tinfoil had not been blocking
the tell-tale signal.

> What's worse, passages like
>
> | Nevertheless, the photon has not
> | been [permanently] absorbed by the atom, so no interaction between
> | the photon and the atom seems to have taken place.
>
> makes me wonder if the authors really think that an absorption with a
> re-emission can be considered as "no interaction".

Ah, but this is why it is called "interaction free measurement" (IFM),
and the authors are not discussing here what they might think per se,
but are instead discussing work done a decade previously by L. Hardy.

Oliver Jennrich

Jun12-04, 07:24 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>* Charlie Stromeyer, writes:\n\n> Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:\n>> > http://arxiv.org/abs/quant-ph/0102109\n>>\n>> The problem with this paper, though, is that it doesn\'t describe a\n>> real experiment, much less presents any measurements, data, anything,\n>> that is likely to show the postulated effects.\n\n> Neither Newton nor Einstein themselves did actual experiments to\n> measure the effects of gravity but this did not prevent their ideas\n> from being correct!\n\nI don\'t doubt that. However, before embarking on a lengthy debate\nabout the implications of an experiment on the interpretation (!) of\nquantum mechanics, it would be wise to actually *perform* the\nexperiment. And be it only to see if the predictions made by the\nauthors are valid.\n\n> Either the above paper is mathematically valid within the formalism of\n> quantum theory or it is not.\n\nThere is, unfortunately, a third possibility: The paper can be\nmathematically valid, but there is no way to prepare a system as\ndescribed.\n\n>> makes me wonder if the authors really think that an absorption with a\n>> re-emission can be considered as "no interaction".\n\n> Ah, but this is why it is called "interaction free measurement" (IFM),\n> and the authors are not discussing here what they might think per se,\n> but are instead discussing work done a decade previously by L. Hardy.\n\nThat is just words. Just because I call something \'IFM\' doesn\'t mean it\nactually *is* interaction-free. A bit like the old \'lasing without\ninversion\'-stuff, where there is inversion, but by calling it LWI it\nlooks somewhat magical.\n\nThe authors muse about the fact, that the interference pattern\nchanges, even if the photon was not absorbed by the atoms.\n\nWhenever I come across statements like that I cannot help wondering\nif it has been realised, that this experiment would not work with\nsingle photons, mainly because you cannot *prepare* a single\nphoton. All we can do is to prepare (coherent or nonclassical) states,\nthat contain one photon *on average*. Sticking to the experimentally\nmost convenient state, the coherent state, we get something that has a\n*phase*. And while the expectation value of the *number* of photons\nmight not change, the *phase* (and hence the interference pattern)\nwill. In essence this can be observed with an interfereometer \'filled\'\nwith free space: change the difference in armlength will change the\ninterference pattern.\n\nNothing magical about that, certainly not \'interaction free\' but just\nan interaction that preserves photon numbers.\n--\nSpace - the final frontier\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Charlie Stromeyer, writes:

> Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:
>> > http://arxiv.org/abs/http://www.arxiv.org/abs/quant-ph/0102109
>>
>> The problem with this paper, though, is that it doesn't describe a
>> real experiment, much less presents any measurements, data, anything,
>> that is likely to show the postulated effects.

> Neither Newton nor Einstein themselves did actual experiments to
> measure the effects of gravity but this did not prevent their ideas
> from being correct!

I don't doubt that. However, before embarking on a lengthy debate
about the implications of an experiment on the interpretation (!) of
quantum mechanics, it would be wise to actually *perform* the
experiment. And be it only to see if the predictions made by the
authors are valid.

> Either the above paper is mathematically valid within the formalism of
> quantum theory or it is not.

There is, unfortunately, a third possibility: The paper can be
mathematically valid, but there is no way to prepare a system as
described.

>> makes me wonder if the authors really think that an absorption with a
>> re-emission can be considered as "no interaction".

> Ah, but this is why it is called "interaction free measurement" (IFM),
> and the authors are not discussing here what they might think per se,
> but are instead discussing work done a decade previously by L. Hardy.

That is just words. Just because I call something 'IFM' doesn't mean it
actually *is* interaction-free. A bit like the old 'lasing without
inversion'-stuff, where there is inversion, but by calling it LWI it
looks somewhat magical.

The authors muse about the fact, that the interference pattern
changes, even if the photon was not absorbed by the atoms.

Whenever I come across statements like that I cannot help wondering
if it has been realised, that this experiment would not work with
single photons, mainly because you cannot *prepare* a single
photon. All we can do is to prepare (coherent or nonclassical) states,
that contain one photon *on average*. Sticking to the experimentally
most convenient state, the coherent state, we get something that has a
*phase*. And while the expectation value of the *number* of photons
might not change, the *phase* (and hence the interference pattern)
will. In essence this can be observed with an interfereometer 'filled'
with free space: change the difference in armlength will change the
interference pattern.

Nothing magical about that, certainly not 'interaction free' but just
an interaction that preserves photon numbers.
--
Space - the final frontier

Charlie Stromeyer Jr.

Jun14-04, 03:09 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:\n\n> > Either the above paper is mathematically valid within the formalism of\n> > quantum theory or it is not.\n>\n> There is, unfortunately, a third possibility: The paper can be\n> mathematically valid, but there is no way to prepare a system as\n> described.\n\nWell, we cannot observe Hawking radiation either but this does not\nnecessarily mean that Hawking is wrong.\n\n> That is just words. Just because I call something \'IFM\' doesn\'t mean it\n> actually *is* interaction-free.\n\nYou are partially correct. Here is a more accurate description from\nquant-ph/0109105:\n\n"As pointed out by many, IFM are not\ntruly interaction free, but would be better\ndescribed by "energy-exchange-free\ninteractions" [20, 21]. IFM are a way of\nmeasuring, usually by means of an interferometer,\nwhere the probed object has\nonly a small probability of absorbing energy\n[20, 21, 22, 23, 24]. When applied to the\nmeasurement of the state of a quantum system,\nthe probe becomes entangled with the\nprobed object, with only a small probability\nof irreversibly losing the quantum information.\nThe information is simply transferred\nfrom one system to non-local correlations.\nNo information is gained on the state of\nthe object and the wave-function does not\ncollapse until one performs a read-out on the\nprobe."\n\n> The authors muse about the fact, that the interference pattern\n> changes, even if the photon was not absorbed by the atoms.\n\nInterference is defined more generally than that which is merely an\nobservable interference pattern. Interference can be any effect\nindicative of the superposition of optical fields, in the sense that\ntheir field strengths add rather than their intensities, i.e. the\nintensity correlations rather than the intensity itself.\n\n> Whenever I come across statements like that I cannot help wondering\n> if it has been realised, that this experiment would not work with\n> single photons, mainly because you cannot *prepare* a single\n> photon.\n\nI don\'t know because I first have to read the scientific paper\nassociated with the news announcement posted to this forum recently by\n"neutron". I do know that Bell inequality statistics cannot be\ndemonstrated via a series of same-spin measurements.\n\nI also know that a single photon can potentially have multiple sources\nas explained in "Interference Between Independent Photons" by H. Paul,\nRevs. of Mod. Physics, v. 58 (1986), pp. 209-231.\n\nHowever, your intuitions may still be someho correct because I have\nnot yet read anything e.g. about photon propagation in noncommutative\nQED, and it will still take me some time to review this overall topic.\nThere is even a paper which proposes a simple classical (i.e.\nnon-quantum) experiment for distinguishing between noncommutative\nspace vs. the usual (commutative) view of space:\n\nhttp://arxiv.org/abs/hep-th/0311134\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oliver Jennrich <oliver.jennrich@gmx.net> wrote in message news:

> > Either the above paper is mathematically valid within the formalism of
> > quantum theory or it is not.
>
> There is, unfortunately, a third possibility: The paper can be
> mathematically valid, but there is no way to prepare a system as
> described.

Well, we cannot observe Hawking radiation either but this does not
necessarily mean that Hawking is wrong.

> That is just words. Just because I call something 'IFM' doesn't mean it
> actually *is* interaction-free.

You are partially correct. Here is a more accurate description from
http://www.arxiv.org/abs/quant-ph/0109105:

"As pointed out by many, IFM are not
truly interaction free, but would be better
described by "energy-exchange-free
interactions" [20, 21]. IFM are a way of
measuring, usually by means of an interferometer,
where the probed object has
only a small probability of absorbing energy
[20, 21, 22, 23, 24]. When applied to the
measurement of the state of a quantum system,
the probe becomes entangled with the
probed object, with only a small probability
of irreversibly losing the quantum information.
The information is simply transferred
from one system to non-local correlations.
No information is gained on the state of
the object and the wave-function does not
collapse until one performs a read-out on the
probe."

> The authors muse about the fact, that the interference pattern
> changes, even if the photon was not absorbed by the atoms.

Interference is defined more generally than that which is merely an
observable interference pattern. Interference can be any effect
indicative of the superposition of optical fields, in the sense that
their field strengths add rather than their intensities, i.e. the
intensity correlations rather than the intensity itself.

> Whenever I come across statements like that I cannot help wondering
> if it has been realised, that this experiment would not work with
> single photons, mainly because you cannot *prepare* a single
> photon.

I don't know because I first have to read the scientific paper
associated with the news announcement posted to this forum recently by
"neutron". I do know that Bell inequality statistics cannot be
demonstrated via a series of same-spin measurements.

I also know that a single photon can potentially have multiple sources
as explained in "Interference Between Independent Photons" by H. Paul,
Revs. of Mod. Physics, v. 58 (1986), pp. 209-231.

However, your intuitions may still be someho correct because I have
not yet read anything e.g. about photon propagation in noncommutative
QED, and it will still take me some time to review this overall topic.
There is even a paper which proposes a simple classical (i.e.
non-quantum) experiment for distinguishing between noncommutative
space vs. the usual (commutative) view of space:

http://arxiv.org/abs/http://www.arxiv.org/abs/hep-th/0311134