View Full Version : Virtual Particles
Ian Taylor
Sep25-04, 05:03 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>A number of people here have stated that virtual particles are not\n"real", and just a calculational device. This has confused me for two\nreasons\n\n1. I was always taught that particles such as electrons are\nindistinguishable, so that if you swap two electrons around you would\nnever be able to tell. So if a virtual electron-antielectron pair is\ncreated, if we could somehow swap the virtual electron for a real\nelectron how would we know ? However this indistinguishability idea\nseems (to me at least) to be at variance with the view that virtual\nparticles are not real\n\n2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\nphysical picture painted is that a virtual pair of particles appears\nnear the event horizon, and one falls in to the black hole, and the\nother is emitted (at least this is how I have seen it explained). In\nthis case the virtual particles (which according to some don\'t really\nexist) somehow become real !\n\nClearly I am of the view that virtual particles are just as real as\nreal particles, but I am prepared to change my mind if someone puts\nforward a sufficiently convincing argument to the contrary.\n\nIan Taylor\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>A number of people here have stated that virtual particles are not
"real", and just a calculational device. This has confused me for two
reasons
1. I was always taught that particles such as electrons are
indistinguishable, so that if you swap two electrons around you would
never be able to tell. So if a virtual electron-antielectron pair is
created, if we could somehow swap the virtual electron for a real
electron how would we know ? However this indistinguishability idea
seems (to me at least) to be at variance with the view that virtual
particles are not real
2. In Stephen Hawking's calculation of a black hole's temperature, the
physical picture painted is that a virtual pair of particles appears
near the event horizon, and one falls in to the black hole, and the
other is emitted (at least this is how I have seen it explained). In
this case the virtual particles (which according to some don't really
exist) somehow become real !
Clearly I am of the view that virtual particles are just as real as
real particles, but I am prepared to change my mind if someone puts
forward a sufficiently convincing argument to the contrary.
Ian Taylor
Uncle Al
Sep26-04, 03:20 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>Ian Taylor wrote:\n>\n> A number of people here have stated that virtual particles are not\n> "real", and just a calculational device. This has confused me for two\n> reasons\n>\n> 1. I was always taught that particles such as electrons are\n> indistinguishable, so that if you swap two electrons around you would\n> never be able to tell. So if a virtual electron-antielectron pair is\n> created, if we could somehow swap the virtual electron for a real\n> electron how would we know ? However this indistinguishability idea\n> seems (to me at least) to be at variance with the view that virtual\n> particles are not real\n>\n> 2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\n> physical picture painted is that a virtual pair of particles appears\n> near the event horizon, and one falls in to the black hole, and the\n> other is emitted (at least this is how I have seen it explained). In\n> this case the virtual particles (which according to some don\'t really\n> exist) somehow become real !\n>\n> Clearly I am of the view that virtual particles are just as real as\n> real particles, but I am prepared to change my mind if someone puts\n> forward a sufficiently convincing argument to the contrary.\n\nCasmir effect, Lamb shift, Rabi vacuum oscillations, electron\nanomalous g-factor... How would you rationalize the Casimir effect,\nan etalon excluding virtual modes to measurable effect with force\nvarying as the inverse fourth power of the separation, as "just a\ncalculational device?"\n\n--\nUncle Al\nhttp://www.mazepath.com/uncleal/\n(Toxic URL! Unsafe for children and most mammals)\nhttp://www.mazepath.com/uncleal/qz.pdf\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>Ian Taylor wrote:
>
> A number of people here have stated that virtual particles are not
> "real", and just a calculational device. This has confused me for two
> reasons
>
> 1. I was always taught that particles such as electrons are
> indistinguishable, so that if you swap two electrons around you would
> never be able to tell. So if a virtual electron-antielectron pair is
> created, if we could somehow swap the virtual electron for a real
> electron how would we know ? However this indistinguishability idea
> seems (to me at least) to be at variance with the view that virtual
> particles are not real
>
> 2. In Stephen Hawking's calculation of a black hole's temperature, the
> physical picture painted is that a virtual pair of particles appears
> near the event horizon, and one falls in to the black hole, and the
> other is emitted (at least this is how I have seen it explained). In
> this case the virtual particles (which according to some don't really
> exist) somehow become real !
>
> Clearly I am of the view that virtual particles are just as real as
> real particles, but I am prepared to change my mind if someone puts
> forward a sufficiently convincing argument to the contrary.
Casmir effect, Lamb shift, Rabi vacuum oscillations, electron
anomalous g-factor... How would you rationalize the Casimir effect,
an etalon excluding virtual modes to measurable effect with force
varying as the inverse fourth power of the separation, as "just a
calculational device?"
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
greywolf42
Sep27-04, 03:31 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\n\n"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\nnews:2eefbf19.0409250112.2abcaafe@posting .google.com...\n> A number of people here have stated that virtual particles are not\n> "real", and just a calculational device. This has confused me for two\n> reasons\n>\n> 1. I was always taught that particles such as electrons are\n> indistinguishable, so that if you swap two electrons around you would\n> never be able to tell.\n\nYep. Electrons are electrons.\n\n> So if a virtual electron-antielectron pair is\n> created, if we could somehow swap the virtual electron for a real\n> electron how would we know ?\n\nSimply because a \'virtual electron\' is not real. The mathematical device of\na \'virtual electron\' is fundamentally distinguishable from a \'real\nelectron.\' The former is not observable at all. The latter is observable.\n\nDon\'t be confused by the word \'electron\' in the phrase \'virtual electron.\'\nThe two are as different as cheese and chalk.\n\n> However this indistinguishability idea\n> seems (to me at least) to be at variance with the view that virtual\n> particles are not real.\n\nIt is \'at variance\' because a virtual electron is not the same as a real\nelectron.\n\n> 2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\n> physical picture painted is that a virtual pair of particles appears\n> near the event horizon, and one falls in to the black hole, and the\n> other is emitted (at least this is how I have seen it explained). In\n> this case the virtual particles (which according to some don\'t really\n> exist) somehow become real !\n\nA virtual particle that "exited" the black hole would remain a virtual\nparticle. It would not really exist.\n\n> Clearly I am of the view that virtual particles are just as real as\n> real particles, but I am prepared to change my mind if someone puts\n> forward a sufficiently convincing argument to the contrary.\n\nWhat is the basis for your opinion that virtual particles are \'just as real\'\nas real particles. When the former -- by definition -- can never be\ndirectly observed. While the latter can be directly observed?\n\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for e-mail}\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>"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
news:2eefbf19.0409250112.2abcaafe@posting.google.c om...
> A number of people here have stated that virtual particles are not
> "real", and just a calculational device. This has confused me for two
> reasons
>
> 1. I was always taught that particles such as electrons are
> indistinguishable, so that if you swap two electrons around you would
> never be able to tell.
Yep. Electrons are electrons.
> So if a virtual electron-antielectron pair is
> created, if we could somehow swap the virtual electron for a real
> electron how would we know ?
Simply because a 'virtual electron' is not real. The mathematical device of
a 'virtual electron' is fundamentally distinguishable from a 'real
electron.' The former is not observable at all. The latter is observable.
Don't be confused by the word 'electron' in the phrase 'virtual electron.'
The two are as different as cheese and chalk.
> However this indistinguishability idea
> seems (to me at least) to be at variance with the view that virtual
> particles are not real.
It is 'at variance' because a virtual electron is not the same as a real
electron.
> 2. In Stephen Hawking's calculation of a black hole's temperature, the
> physical picture painted is that a virtual pair of particles appears
> near the event horizon, and one falls in to the black hole, and the
> other is emitted (at least this is how I have seen it explained). In
> this case the virtual particles (which according to some don't really
> exist) somehow become real !
A virtual particle that "exited" the black hole would remain a virtual
particle. It would not really exist.
> Clearly I am of the view that virtual particles are just as real as
> real particles, but I am prepared to change my mind if someone puts
> forward a sufficiently convincing argument to the contrary.
What is the basis for your opinion that virtual particles are 'just as real'
as real particles. When the former -- by definition -- can never be
directly observed. While the latter can be directly observed?
--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}
Benjamin Schulz
Sep27-04, 03:31 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>\nUncle Al wrote:\n\n> Casmir effect, Lamb shift, Rabi vacuum oscillations, electron\n> anomalous g-factor... How would you rationalize the Casimir effect,\n>\n\nBTW:\nThe Casimir effect can be explained as an attraction of conductive\nuncharged bodies which is due to fluctuations of their electrons and\ninduction of their mirror charges. For details see here:\n\n> M. Bordag, U. Mohideen and V. M. Mostepanenko\n> New Developments in the Casimir Effect\n> Physics Reports 353 (2001) 1 - 205\n\nWithout the conductivity of the bodies, one would not have a Casimir effect.\n\nsincerely\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>Uncle Al wrote:
> Casmir effect, Lamb shift, Rabi vacuum oscillations, electron
> anomalous g-factor... How would you rationalize the Casimir effect,
>
BTW:
The Casimir effect can be explained as an attraction of conductive
uncharged bodies which is due to fluctuations of their electrons and
induction of their mirror charges. For details see here:
> M. Bordag, U. Mohideen and V. M. Mostepanenko
> New Developments in the Casimir Effect
> Physics Reports 353 (2001) 1 - 205
Without the conductivity of the bodies, one would not have a Casimir effect.
sincerely
FrediFizzx
Sep27-04, 03:31 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"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\nnews:2eefbf19.0409250112.2abcaafe@posting .google.com...\n| A number of people here have stated that virtual particles are not\n| "real", and just a calculational device. This has confused me for two\n| reasons\n[snip]\n| Clearly I am of the view that virtual particles are just as real as\n| real particles, but I am prepared to change my mind if someone puts\n| forward a sufficiently convincing argument to the contrary.\n\nI am of that same view. IMHO, if you don\'t have instantaneous interactions\nbetween quantum objects, then virtual particles have to be "real". And\nwhat\'s more, is that the concept of "less than virtual" particles could be\n"real" also must be considered.\n\nFrediFizzx\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>"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
news:2eefbf19.0409250112.2abcaafe@posting.google.c om...
| A number of people here have stated that virtual particles are not
| "real", and just a calculational device. This has confused me for two
| reasons
[snip]
| Clearly I am of the view that virtual particles are just as real as
| real particles, but I am prepared to change my mind if someone puts
| forward a sufficiently convincing argument to the contrary.
I am of that same view. IMHO, if you don't have instantaneous interactions
between quantum objects, then virtual particles have to be "real". And
what's more, is that the concept of "less than virtual" particles could be
"real" also must be considered.
FrediFizzx
Ian Taylor
Sep28-04, 10:20 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\n"greywolf42" <mingstb@marssim-ss.com> wrote in message news:<EtL5d.11865\\$o06.10345@news.flashnewsgroups .com>...\n> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\n> news:2eefbf19.0409250112.2abcaafe@posting.google.c om...\n> > A number of people here have stated that virtual particles are not\n> > "real", and just a calculational device. This has confused me for two\n> > reasons\n> >\n> > 1. I was always taught that particles such as electrons are\n> > indistinguishable, so that if you swap two electrons around you would\n> > never be able to tell.\n>\n> Yep. Electrons are electrons.\n>\n> > So if a virtual electron-antielectron pair is\n> > created, if we could somehow swap the virtual electron for a real\n> > electron how would we know ?\n>\n> Simply because a \'virtual electron\' is not real. The mathematical device of\n> a \'virtual electron\' is fundamentally distinguishable from a \'real\n> electron.\' The former is not observable at all. The latter is observable.\n>\n> Don\'t be confused by the word \'electron\' in the phrase \'virtual electron.\'\n> The two are as different as cheese and chalk.\n>\n> > However this indistinguishability idea\n> > seems (to me at least) to be at variance with the view that virtual\n> > particles are not real.\n>\n> It is \'at variance\' because a virtual electron is not the same as a real\n> electron.\n>\n> > 2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\n> > physical picture painted is that a virtual pair of particles appears\n> > near the event horizon, and one falls in to the black hole, and the\n> > other is emitted (at least this is how I have seen it explained). In\n> > this case the virtual particles (which according to some don\'t really\n> > exist) somehow become real !\n>\n> A virtual particle that "exited" the black hole would remain a virtual\n> particle. It would not really exist.\n>\n> > Clearly I am of the view that virtual particles are just as real as\n> > real particles, but I am prepared to change my mind if someone puts\n> > forward a sufficiently convincing argument to the contrary.\n>\n> What is the basis for your opinion that virtual particles are \'just as real\'\n> as real particles. When the former -- by definition -- can never be\n> directly observed. While the latter can be directly observed?\n\nAs I said in my original e-mail if someone comes up with a convincing\nargument for why virtual particles are not real, I\'m prepared to\nchange my mind. Making the above statements (such as a virtual\nelectron is as different to a real electron as chalk is to cheese is\nnot to my mind at all convincing). As far as I know a virtual\nparticle-antiparticle pair, of total energy dE can exist for a time\ndt, provided dt and dE satisfy Heisenberg\'s uncertainty principle. For\nthe time that they exist I don\'t see any reason that the particles are\nnot just as real as any other. As for observational evidence, the fact\nthat we cannot observe them is not a problem - after all try observing\na single quark ! We know that they are they because otherwise the\ncharge on an electron would be quite different. Also there are effects\nwhich are attributed to virtal particles such as the Casimir effect\nwhich are observable. I still am yet to be convinced by any argument\nthat these particles are not real.\n\nIan Taylor\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>"greywolf42" <mingstb@marssim-ss.com> wrote in message news:<EtL5d.11865$o06.10345@news.flashnewsgroups.com>...
> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
> news:2eefbf19.0409250112.2abcaafe@posting.google.c om...
> > A number of people here have stated that virtual particles are not
> > "real", and just a calculational device. This has confused me for two
> > reasons
> >
> > 1. I was always taught that particles such as electrons are
> > indistinguishable, so that if you swap two electrons around you would
> > never be able to tell.
>
> Yep. Electrons are electrons.
>
> > So if a virtual electron-antielectron pair is
> > created, if we could somehow swap the virtual electron for a real
> > electron how would we know ?
>
> Simply because a 'virtual electron' is not real. The mathematical device of
> a 'virtual electron' is fundamentally distinguishable from a 'real
> electron.' The former is not observable at all. The latter is observable.
>
> Don't be confused by the word 'electron' in the phrase 'virtual electron.'
> The two are as different as cheese and chalk.
>
> > However this indistinguishability idea
> > seems (to me at least) to be at variance with the view that virtual
> > particles are not real.
>
> It is 'at variance' because a virtual electron is not the same as a real
> electron.
>
> > 2. In Stephen Hawking's calculation of a black hole's temperature, the
> > physical picture painted is that a virtual pair of particles appears
> > near the event horizon, and one falls in to the black hole, and the
> > other is emitted (at least this is how I have seen it explained). In
> > this case the virtual particles (which according to some don't really
> > exist) somehow become real !
>
> A virtual particle that "exited" the black hole would remain a virtual
> particle. It would not really exist.
>
> > Clearly I am of the view that virtual particles are just as real as
> > real particles, but I am prepared to change my mind if someone puts
> > forward a sufficiently convincing argument to the contrary.
>
> What is the basis for your opinion that virtual particles are 'just as real'
> as real particles. When the former -- by definition -- can never be
> directly observed. While the latter can be directly observed?
As I said in my original e-mail if someone comes up with a convincing
argument for why virtual particles are not real, I'm prepared to
change my mind. Making the above statements (such as a virtual
electron is as different to a real electron as chalk is to cheese is
not to my mind at all convincing). As far as I know a virtual
particle-antiparticle pair, of total energy dE can exist for a time
dt, provided dt and dE satisfy Heisenberg's uncertainty principle. For
the time that they exist I don't see any reason that the particles are
not just as real as any other. As for observational evidence, the fact
that we cannot observe them is not a problem - after all try observing
a single quark ! We know that they are they because otherwise the
charge on an electron would be quite different. Also there are effects
which are attributed to virtal particles such as the Casimir effect
which are observable. I still am yet to be convinced by any argument
that these particles are not real.
Ian Taylor
Arnold Neumaier
Sep28-04, 10:20 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\nUncle Al wrote:\n> Ian Taylor wrote:\n>\n>>A number of people here have stated that virtual particles are not\n>>"real", and just a calculational device. This has confused me for two\n>>reasons\n>>\n>>1. I was always taught that particles such as electrons are\n>>indistinguishable, so that if you swap two electrons around you would\n>>never be able to tell. So if a virtual electron-antielectron pair is\n>>created, if we could somehow swap the virtual electron for a real\n>>electron how would we know ? However this indistinguishability idea\n>>seems (to me at least) to be at variance with the view that virtual\n>>particles are not real\n\n\n>>\n>>2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\n>>physical picture painted is that a virtual pair of particles appears\n>>near the event horizon, and one falls in to the black hole, and the\n>>other is emitted (at least this is how I have seen it explained). In\n>>this case the virtual particles (which according to some don\'t really\n>>exist) somehow become real !\n>>\n>>Clearly I am of the view that virtual particles are just as real as\n>>real particles, but I am prepared to change my mind if someone puts\n>>forward a sufficiently convincing argument to the contrary.\n\nThis is explained at length in the secition\n\'\'How real are \'virtual particles\'?\'\' of my theoretical physics FAQ at\nhttp://www.mat.univie.ac.at/~neum/physics-faq.txt\n\nIf you don\'t find this convincing, please state your reasons, and\nI\'ll improve the argumentation.\n\n\n> Casmir effect, Lamb shift, Rabi vacuum oscillations, electron\n> anomalous g-factor... How would you rationalize the Casimir effect,\n> an etalon excluding virtual modes to measurable effect with force\n> varying as the inverse fourth power of the separation, as "just a\n> calculational device?"\n\nOf course, physicists would not talk of virtual particles if the concept\nhad no relevance at all. However, in terms of real particles, the\nabove effects all show up as a consequence of renormalized, effective\ninteractions. Only these have a real meaning in terms of observable\neffects.\n\n\nArnold Neumaier\n\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>Uncle Al wrote:
> Ian Taylor wrote:
>
>>A number of people here have stated that virtual particles are not
>>"real", and just a calculational device. This has confused me for two
>>reasons
>>
>>1. I was always taught that particles such as electrons are
>>indistinguishable, so that if you swap two electrons around you would
>>never be able to tell. So if a virtual electron-antielectron pair is
>>created, if we could somehow swap the virtual electron for a real
>>electron how would we know ? However this indistinguishability idea
>>seems (to me at least) to be at variance with the view that virtual
>>particles are not real
>>
>>2. In Stephen Hawking's calculation of a black hole's temperature, the
>>physical picture painted is that a virtual pair of particles appears
>>near the event horizon, and one falls in to the black hole, and the
>>other is emitted (at least this is how I have seen it explained). In
>>this case the virtual particles (which according to some don't really
>>exist) somehow become real !
>>
>>Clearly I am of the view that virtual particles are just as real as
>>real particles, but I am prepared to change my mind if someone puts
>>forward a sufficiently convincing argument to the contrary.
This is explained at length in the secition
''How real are 'virtual particles'?'' of my theoretical physics FAQ at
http://www.mat.univie.ac.at/~neum/physics-faq.txt
If you don't find this convincing, please state your reasons, and
I'll improve the argumentation.
> Casmir effect, Lamb shift, Rabi vacuum oscillations, electron
> anomalous g-factor... How would you rationalize the Casimir effect,
> an etalon excluding virtual modes to measurable effect with force
> varying as the inverse fourth power of the separation, as "just a
> calculational device?"
Of course, physicists would not talk of virtual particles if the concept
had no relevance at all. However, in terms of real particles, the
above effects all show up as a consequence of renormalized, effective
interactions. Only these have a real meaning in terms of observable
effects.
Arnold Neumaier
Greysky
Sep29-04, 08:28 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>"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\nnews:2eefbf19.0409271242.48e55ac1@posting .google.com...\n>\n>\n> "greywolf42" <mingstb@marssim-ss.com> wrote in message\n> news:<EtL5d.11865\\$o06.10345@news.flashnewsgroups .com>...\n>> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\n>> news:2eefbf19.0409250112.2abcaafe@posting.google.c om...\n>> > A number of people here have stated that virtual particles are not\n>> > "real", and just a calculational device. This has confused me for two\n>> > reasons\n>> >\n>> > 1. I was always taught that particles such as electrons are\n>> > indistinguishable, so that if you swap two electrons around you would\n>> > never be able to tell.\n>>\n>> Yep. Electrons are electrons.\n>>\n>> > So if a virtual electron-antielectron pair is\n>> > created, if we could somehow swap the virtual electron for a real\n>> > electron how would we know ?\n>>\n>> Simply because a \'virtual electron\' is not real. The mathematical device\n>> of\n>> a \'virtual electron\' is fundamentally distinguishable from a \'real\n>> electron.\' The former is not observable at all. The latter is\n>> observable.\n>>\n>> Don\'t be confused by the word \'electron\' in the phrase \'virtual\n>> electron.\'\n>> The two are as different as cheese and chalk.\n>>\n>> > However this indistinguishability idea\n>> > seems (to me at least) to be at variance with the view that virtual\n>> > particles are not real.\n>>\n>> It is \'at variance\' because a virtual electron is not the same as a real\n>> electron.\n>>\n>> > 2. In Stephen Hawking\'s calculation of a black hole\'s temperature, the\n>> > physical picture painted is that a virtual pair of particles appears\n>> > near the event horizon, and one falls in to the black hole, and the\n>> > other is emitted (at least this is how I have seen it explained). In\n>> > this case the virtual particles (which according to some don\'t really\n>> > exist) somehow become real !\n>>\n>> A virtual particle that "exited" the black hole would remain a virtual\n>> particle. It would not really exist.\n>>\n>> > Clearly I am of the view that virtual particles are just as real as\n>> > real particles, but I am prepared to change my mind if someone puts\n>> > forward a sufficiently convincing argument to the contrary.\n>>\n>> What is the basis for your opinion that virtual particles are \'just as\n>> real\'\n>> as real particles. When the former -- by definition -- can never be\n>> directly observed. While the latter can be directly observed?\n>\n> As I said in my original e-mail if someone comes up with a convincing\n> argument for why virtual particles are not real, I\'m prepared to\n> change my mind. Making the above statements (such as a virtual\n> electron is as different to a real electron as chalk is to cheese is\n> not to my mind at all convincing). As far as I know a virtual\n> particle-antiparticle pair, of total energy dE can exist for a time\n> dt, provided dt and dE satisfy Heisenberg\'s uncertainty principle. For\n> the time that they exist I don\'t see any reason that the particles are\n> not just as real as any other. As for observational evidence, the fact\n> that we cannot observe them is not a problem - after all try observing\n> a single quark ! We know that they are they because otherwise the\n> charge on an electron would be quite different. Also there are effects\n> which are attributed to virtal particles such as the Casimir effect\n> which are observable. I still am yet to be convinced by any argument\n> that these particles are not real.\n>\n> Ian Taylor\n\nThey are \'real\' in the sense that imaginary particles can produce physical\neffects that can and are directly measurable. Nuclear force shielding: The\nnuclear forces in an atom are diminished significantly because of the cloud\nof virtual particles which surround the nucleus: if it were not so, some\natoms would have a nuclear force so strong no nucleus above n=5 could exist\nwithout the ensemble collapsing into a tiny black hole. As for the virtual\nparticle that escapes the event horizon of a black hole, it is made real\nbecause it takes energy away from the black hole... and the black hole is\njust a tiny bit smaller because of it. There is a form of \'Brownian Motion\'\nthat occurs for subatomic particles as well - they are buffeted about by\nimpacting with virtual quanta. While virtual particles exist, they behave\njust like their real counterparts: If I were to smash in a pumpkin head\n(this being close to October) with a baseball bat made of virtual particles,\nthe pieces of pumpkin would indeed go flying everywhere. Then the virtual\nbat disappears because it is not \'real\'.... do the pieces of pumpkin return\nto their original positions...no. Now you are left with the apparent paradox\nof how can a imaginary force do real work? So you are right to be suspicious\nof the people who say imaginary particles are \'only a math trick\' to make\ncalculating something easier....\n\nGreysky\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>"Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
news:2eefbf19.0409271242.48e55ac1@posting.google.c om...
>
>
> "greywolf42" <mingstb@marssim-ss.com> wrote in message
> news:<EtL5d.11865$o06.10345@news.flashnewsgroups.com>...
>> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
>> news:2eefbf19.0409250112.2abcaafe@posting.google.c om...
>> > A number of people here have stated that virtual particles are not
>> > "real", and just a calculational device. This has confused me for two
>> > reasons
>> >
>> > 1. I was always taught that particles such as electrons are
>> > indistinguishable, so that if you swap two electrons around you would
>> > never be able to tell.
>>
>> Yep. Electrons are electrons.
>>
>> > So if a virtual electron-antielectron pair is
>> > created, if we could somehow swap the virtual electron for a real
>> > electron how would we know ?
>>
>> Simply because a 'virtual electron' is not real. The mathematical device
>> of
>> a 'virtual electron' is fundamentally distinguishable from a 'real
>> electron.' The former is not observable at all. The latter is
>> observable.
>>
>> Don't be confused by the word 'electron' in the phrase 'virtual
>> electron.'
>> The two are as different as cheese and chalk.
>>
>> > However this indistinguishability idea
>> > seems (to me at least) to be at variance with the view that virtual
>> > particles are not real.
>>
>> It is 'at variance' because a virtual electron is not the same as a real
>> electron.
>>
>> > 2. In Stephen Hawking's calculation of a black hole's temperature, the
>> > physical picture painted is that a virtual pair of particles appears
>> > near the event horizon, and one falls in to the black hole, and the
>> > other is emitted (at least this is how I have seen it explained). In
>> > this case the virtual particles (which according to some don't really
>> > exist) somehow become real !
>>
>> A virtual particle that "exited" the black hole would remain a virtual
>> particle. It would not really exist.
>>
>> > Clearly I am of the view that virtual particles are just as real as
>> > real particles, but I am prepared to change my mind if someone puts
>> > forward a sufficiently convincing argument to the contrary.
>>
>> What is the basis for your opinion that virtual particles are 'just as
>> real'
>> as real particles. When the former -- by definition -- can never be
>> directly observed. While the latter can be directly observed?
>
> As I said in my original e-mail if someone comes up with a convincing
> argument for why virtual particles are not real, I'm prepared to
> change my mind. Making the above statements (such as a virtual
> electron is as different to a real electron as chalk is to cheese is
> not to my mind at all convincing). As far as I know a virtual
> particle-antiparticle pair, of total energy dE can exist for a time
> dt, provided dt and dE satisfy Heisenberg's uncertainty principle. For
> the time that they exist I don't see any reason that the particles are
> not just as real as any other. As for observational evidence, the fact
> that we cannot observe them is not a problem - after all try observing
> a single quark ! We know that they are they because otherwise the
> charge on an electron would be quite different. Also there are effects
> which are attributed to virtal particles such as the Casimir effect
> which are observable. I still am yet to be convinced by any argument
> that these particles are not real.
>
> Ian Taylor
They are 'real' in the sense that imaginary particles can produce physical
effects that can and are directly measurable. Nuclear force shielding: The
nuclear forces in an atom are diminished significantly because of the cloud
of virtual particles which surround the nucleus: if it were not so, some
atoms would have a nuclear force so strong no nucleus above n=5 could exist
without the ensemble collapsing into a tiny black hole. As for the virtual
particle that escapes the event horizon of a black hole, it is made real
because it takes energy away from the black hole... and the black hole is
just a tiny bit smaller because of it. There is a form of 'Brownian Motion'
that occurs for subatomic particles as well - they are buffeted about by
impacting with virtual quanta. While virtual particles exist, they behave
just like their real counterparts: If I were to smash in a pumpkin head
(this being close to October) with a baseball bat made of virtual particles,
the pieces of pumpkin would indeed go flying everywhere. Then the virtual
bat disappears because it is not 'real'.... do the pieces of pumpkin return
to their original positions...no. Now you are left with the apparent paradox
of how can a imaginary force do real work? So you are right to be suspicious
of the people who say imaginary particles are 'only a math trick' to make
calculating something easier....
Greysky
greywolf42
Sep30-04, 01:46 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\n"Greysky" <greyskynospam@sbcglobal.net> wrote in message\nnews:%si6d.3932\\$nj.2970@newssvr13.news. prodigy.com...\n> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message\n> news:2eefbf19.0409271242.48e55ac1@posting.google.c om...\n> >\n> > "greywolf42" <mingstb@marssim-ss.com> wrote in message\n> > news:<EtL5d.11865\\$o06.10345@news.flashnewsgroups .com>...\n\n{snip higher levels}\n\n> >> What is the basis for your opinion that virtual particles are \'just as\n> >> real\'\n> >> as real particles. When the former -- by definition -- can never be\n> >> directly observed. While the latter can be directly observed?\n> >\n> > As I said in my original e-mail if someone comes up with a convincing\n> > argument for why virtual particles are not real, I\'m prepared to\n> > change my mind. Making the above statements (such as a virtual\n> > electron is as different to a real electron as chalk is to cheese is\n> > not to my mind at all convincing). As far as I know a virtual\n> > particle-antiparticle pair, of total energy dE can exist for a time\n> > dt, provided dt and dE satisfy Heisenberg\'s uncertainty principle. For\n> > the time that they exist I don\'t see any reason that the particles are\n> > not just as real as any other. As for observational evidence, the fact\n> > that we cannot observe them is not a problem - after all try observing\n> > a single quark ! We know that they are they because otherwise the\n> > charge on an electron would be quite different. Also there are effects\n> > which are attributed to virtal particles such as the Casimir effect\n> > which are observable. I still am yet to be convinced by any argument\n> > that these particles are not real.\n>\n> They are \'real\' in the sense that imaginary particles can produce physical\n> effects that can and are directly measurable.\n\nBut the effects may have nothing to do with the theoretical premise. One\ncould easily have said the same about heat proving the existence of\nphlogiston.\n\n> Nuclear force shielding: The\n> nuclear forces in an atom are diminished significantly because of the\n> cloud of virtual particles which surround the nucleus: if it were not so,\n> some atoms would have a nuclear force so strong no nucleus above\n> n=5 could exist without the ensemble collapsing into a tiny black hole.\n\nThis is called assuming your conclusion. You cannot buttress one\nunobservable entity with the theory of that entity.\n\n> As for the virtual\n> particle that escapes the event horizon of a black hole, it is made real\n> because it takes energy away from the black hole... and the black hole is\n> just a tiny bit smaller because of it.\n\nGedanken experiments tell us nothing about the real world. Only about our\ntheories.\n\nBut since energy can be either mass or EM field effects, there is no reason\nfor the virtual particle to exist at all. The energy would come out in some\nother form ... without making the \'virtual particle\' real.\n\n> There is a form of \'Brownian Motion\'\n> that occurs for subatomic particles as well - they are buffeted about by\n> impacting with virtual quanta.\n\nWhile the zitterbegwang is observable (in principle), there is no guarantee\nthat the effect is provided by the \'cause\' of theoretically unobservable\nparticles. Other theories can (and may in future) also predict\nzitterbegwang.\n\n> While virtual particles exist, they behave\n> just like their real counterparts:\n\nA demonstrably false statement. They cannot be observed in the lab. This\nis a fundamental difference.\n\n> If I were to smash in a pumpkin head\n> (this being close to October) with a baseball bat made of virtual\n> particles, the pieces of pumpkin would indeed go flying everywhere.\n> Then the virtual bat disappears because it is not \'real\'.... do the\n> pieces of pumpkin return to their original positions...no.\n\nThis is called proof by assertion. And is a logical fallacy.\n\n> Now you are left with the apparent paradox\n> of how can a imaginary force do real work?\n\nThat is indeed a paradox of the theory.\n\n> So you are right to be suspicious\n> of the people who say imaginary particles are \'only a math trick\' to make\n> calculating something easier....\n\nOne should be suspicious of those who champion \'magical\' particles that do\nreal work without actually existing.\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for e-mail}\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>"Greysky" <greyskynospam@sbcglobal.net> wrote in message
news:%si6d.3932$nj.2970@newssvr13.news.prodigy.com ...
> "Ian Taylor" <iantaylor2uk@yahoo.co.uk> wrote in message
> news:2eefbf19.0409271242.48e55ac1@posting.google.c om...
> >
> > "greywolf42" <mingstb@marssim-ss.com> wrote in message
> > news:<EtL5d.11865$o06.10345@news.flashnewsgroups.com>...
{snip higher levels}
> >> What is the basis for your opinion that virtual particles are 'just as
> >> real'
> >> as real particles. When the former -- by definition -- can never be
> >> directly observed. While the latter can be directly observed?
> >
> > As I said in my original e-mail if someone comes up with a convincing
> > argument for why virtual particles are not real, I'm prepared to
> > change my mind. Making the above statements (such as a virtual
> > electron is as different to a real electron as chalk is to cheese is
> > not to my mind at all convincing). As far as I know a virtual
> > particle-antiparticle pair, of total energy dE can exist for a time
> > dt, provided dt and dE satisfy Heisenberg's uncertainty principle. For
> > the time that they exist I don't see any reason that the particles are
> > not just as real as any other. As for observational evidence, the fact
> > that we cannot observe them is not a problem - after all try observing
> > a single quark ! We know that they are they because otherwise the
> > charge on an electron would be quite different. Also there are effects
> > which are attributed to virtal particles such as the Casimir effect
> > which are observable. I still am yet to be convinced by any argument
> > that these particles are not real.
>
> They are 'real' in the sense that imaginary particles can produce physical
> effects that can and are directly measurable.
But the effects may have nothing to do with the theoretical premise. One
could easily have said the same about heat proving the existence of
phlogiston.
> Nuclear force shielding: The
> nuclear forces in an atom are diminished significantly because of the
> cloud of virtual particles which surround the nucleus: if it were not so,
> some atoms would have a nuclear force so strong no nucleus above
> n=5 could exist without the ensemble collapsing into a tiny black hole.
This is called assuming your conclusion. You cannot buttress one
unobservable entity with the theory of that entity.
> As for the virtual
> particle that escapes the event horizon of a black hole, it is made real
> because it takes energy away from the black hole... and the black hole is
> just a tiny bit smaller because of it.
Gedanken experiments tell us nothing about the real world. Only about our
theories.
But since energy can be either mass or EM field effects, there is no reason
for the virtual particle to exist at all. The energy would come out in some
other form ... without making the 'virtual particle' real.
> There is a form of 'Brownian Motion'
> that occurs for subatomic particles as well - they are buffeted about by
> impacting with virtual quanta.
While the zitterbegwang is observable (in principle), there is no guarantee
that the effect is provided by the 'cause' of theoretically unobservable
particles. Other theories can (and may in future) also predict
zitterbegwang.
> While virtual particles exist, they behave
> just like their real counterparts:
A demonstrably false statement. They cannot be observed in the lab. This
is a fundamental difference.
> If I were to smash in a pumpkin head
> (this being close to October) with a baseball bat made of virtual
> particles, the pieces of pumpkin would indeed go flying everywhere.
> Then the virtual bat disappears because it is not 'real'.... do the
> pieces of pumpkin return to their original positions...no.
This is called proof by assertion. And is a logical fallacy.
> Now you are left with the apparent paradox
> of how can a imaginary force do real work?
That is indeed a paradox of the theory.
> So you are right to be suspicious
> of the people who say imaginary particles are 'only a math trick' to make
> calculating something easier....
One should be suspicious of those who champion 'magical' particles that do
real work without actually existing.
--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}
<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>\nGreysky <greyskynospam@sbcglobal.net> writes\n>They are \'real\' in the sense that imaginary particles can produce physical\n>effects that can and are directly measurable. Nuclear force shielding: The\n>nuclear forces in an atom are diminished significantly because of the cloud\n>of virtual particles which surround the nucleus: if it were not so, some\n>atoms would have a nuclear force so strong no nucleus above n=5 could exist\n>without the ensemble collapsing into a tiny black hole. As for\n\nIs that strictly the case?\nOne thing about real particles is that we can measure them directly.\nSingly.\n\nSurely the effect you mention above (and the others) is an effect of\nmany (probably an infinite number) of virtual particles. I believe that\nsome claim that virtual particles are but a convenient description of\nelements of a field. We can (I believe) replace the electric field by a\nswarm of virtual photons, does this mean virtual photons are real?\n\nPersonally I prefer to wield occham\'s razor in situations like this. I\nprefer a field as a simpler description to an infinity of transient off-\nshell particles none of which has ever been seen individually.\n\nThat said I would be perfectly happy to use them if I only knew how one\ndid as they appear to be a very convenient mathematical visualisation.\n\nOf course I am somewhat extreme in that I see the electron not as a\npoint particle, but as a pure field (admittedly mostly confined to a\nsmall volume).\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nUse oz@farmeroz.port995.com [ozacoohdb@despammed.com functions].\nBTOPENWORLD address has ceased. DEMON address has ceased.\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>Greysky <greyskynospam@sbcglobal.net> writes
>They are 'real' in the sense that imaginary particles can produce physical
>effects that can and are directly measurable. Nuclear force shielding: The
>nuclear forces in an atom are diminished significantly because of the cloud
>of virtual particles which surround the nucleus: if it were not so, some
>atoms would have a nuclear force so strong no nucleus above n=5 could exist
>without the ensemble collapsing into a tiny black hole. As for
Is that strictly the case?
One thing about real particles is that we can measure them directly.
Singly.
Surely the effect you mention above (and the others) is an effect of
many (probably an infinite number) of virtual particles. I believe that
some claim that virtual particles are but a convenient description of
elements of a field. We can (I believe) replace the electric field by a
swarm of virtual photons, does this mean virtual photons are real?
Personally I prefer to wield occham's razor in situations like this. I
prefer a field as a simpler description to an infinity of transient off-
shell particles none of which has ever been seen individually.
That said I would be perfectly happy to use them if I only knew how one
did as they appear to be a very convenient mathematical visualisation.
Of course I am somewhat extreme in that I see the electron not as a
point particle, but as a pure field (admittedly mostly confined to a
small volume).
--
Oz
This post is worth absolutely nothing and is probably fallacious.
Use oz@farmeroz.port995.com [ozacoohdb@despammed.com functions].
BTOPENWORLD address has ceased. DEMON address has ceased.
p.kinsler@imperial.ac.uk
Oct1-04, 09:43 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>\ngreywolf42 <mingstb@marssim-ss.com> wrote:\n> > Clearly I am of the view that virtual particles are just as real as\n> > real particles, but I am prepared to change my mind if someone puts\n> > forward a sufficiently convincing argument to the contrary.\n\n> What is the basis for your opinion that virtual particles are \'just as real\'\n> as real particles. When the former -- by definition -- can never be\n> directly observed. While the latter can be directly observed?\n\nPerhaps, therefore, we should drop all this confusing "real" and\n"virtual" particle labelling, and refer instead to "observable" and\n"non-observable" particles.\n\nI suggest this because by your own description, the operational\ncriteria is observability, and has nothing to to with the more\nvague and even philosophical notion of realness (or virtual-ness).\n\n--\n---------------------------------+---------------------------------\nDr. Paul Kinsler\nBlackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714\nImperial College London, Dr.Paul.Kinsler@physics.org\nSW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/\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>greywolf42 <mingstb@marssim-ss.com> wrote:
> > Clearly I am of the view that virtual particles are just as real as
> > real particles, but I am prepared to change my mind if someone puts
> > forward a sufficiently convincing argument to the contrary.
> What is the basis for your opinion that virtual particles are 'just as real'
> as real particles. When the former -- by definition -- can never be
> directly observed. While the latter can be directly observed?
Perhaps, therefore, we should drop all this confusing "real" and
"virtual" particle labelling, and refer instead to "observable" and
"non-observable" particles.
I suggest this because by your own description, the operational
criteria is observability, and has nothing to to with the more
vague and even philosophical notion of realness (or virtual-ness).
--
---------------------------------+---------------------------------
Dr. Paul Kinsler
Blackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714
Imperial College London, Dr.Paul.Kinsler@physics.org
SW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/
John Gonsowski
Oct3-04, 03:49 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\niantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409250112.2abcaafe@posting.google. com>...\n>\n> Clearly I am of the view that virtual particles are just as real as\n> real particles, but I am prepared to change my mind if someone puts\n> forward a sufficiently convincing argument to the contrary.\n>\n> Ian Taylor\n\nVirtual particles are like and perhaps related to things like the\nvacuum, complex spacetime, curled up dimensions and many-worlds\nbranches. Kind of hard to be on the surface of a balloon and picture\nwhat the inside is like even if the inside exists more than just\nmathematically.\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>iantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409250112.2abcaafe@posting.google.com>...
>
> Clearly I am of the view that virtual particles are just as real as
> real particles, but I am prepared to change my mind if someone puts
> forward a sufficiently convincing argument to the contrary.
>
> Ian Taylor
Virtual particles are like and perhaps related to things like the
vacuum, complex spacetime, curled up dimensions and many-worlds
branches. Kind of hard to be on the surface of a balloon and picture
what the inside is like even if the inside exists more than just
mathematically.
greywolf42
Oct3-04, 03:49 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\n<p.kinsler@imperial.ac.uk> wrote in message\nnews:ovmv22-vqh.ln1@delillo.lsr.ph.ic.ac.uk...\n>\n> greywolf42 <mingstb@marssim-ss.com> wrote:\n\n{please leave the attributions intact for statements that you leave in the\npost}\n\nIan Taylor:\n> > > Clearly I am of the view that virtual particles are just as real as\n> > > real particles, but I am prepared to change my mind if someone puts\n> > > forward a sufficiently convincing argument to the contrary.\n>\n> > What is the basis for your opinion that virtual particles are \'just as\n> > real\' as real particles. When the former -- by definition -- can\n> > never be directly observed. While the latter can be directly\n> > observed?\n>\n> Perhaps, therefore, we should drop all this confusing "real" and\n> "virtual" particle labelling, and refer instead to "observable" and\n> "non-observable" particles.\n>\n> I suggest this because by your own description, the operational\n> criteria is observability, and has nothing to to with the more\n> vague and even philosophical notion of realness (or virtual-ness).\n\nThat would be OK with me. However, the reason that this is \'my\' criterion\nis because observability is the criterion of the scientific method. If it\nfundamentally cannot be observed, then it is not part of the scientific\nmethod.\n\nThen again, I don\'t believe that changing the name from \'virtual particle\'\nto \'unobservable particle\' would change the argument of those who do and\nthose who don\'t believe in unobservable particles.\n\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for e-mail}\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><p.kinsler@imperial.ac.uk> wrote in message
news:ovmv22-vqh.ln1@delillo.lsr.ph.ic.ac.uk...
>
> greywolf42 <mingstb@marssim-ss.com> wrote:
{please leave the attributions intact for statements that you leave in the
post}
Ian Taylor:
> > > Clearly I am of the view that virtual particles are just as real as
> > > real particles, but I am prepared to change my mind if someone puts
> > > forward a sufficiently convincing argument to the contrary.
>
> > What is the basis for your opinion that virtual particles are 'just as
> > real' as real particles. When the former -- by definition -- can
> > never be directly observed. While the latter can be directly
> > observed?
>
> Perhaps, therefore, we should drop all this confusing "real" and
> "virtual" particle labelling, and refer instead to "observable" and
> "non-observable" particles.
>
> I suggest this because by your own description, the operational
> criteria is observability, and has nothing to to with the more
> vague and even philosophical notion of realness (or virtual-ness).
That would be OK with me. However, the reason that this is 'my' criterion
is because observability is the criterion of the scientific method. If it
fundamentally cannot be observed, then it is not part of the scientific
method.
Then again, I don't believe that changing the name from 'virtual particle'
to 'unobservable particle' would change the argument of those who do and
those who don't believe in unobservable particles.
--
greywolf42
ubi dubium ibi libertas
{remove planet for e-mail}
Igor Khavkine
Oct4-04, 12:21 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>iantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409271242.48e55ac1@posting.google. com>...\n\n> As I said in my original e-mail if someone comes up with a convincing\n> argument for why virtual particles are not real, I\'m prepared to\n> change my mind. Making the above statements (such as a virtual\n> electron is as different to a real electron as chalk is to cheese is\n> not to my mind at all convincing). As far as I know a virtual\n> particle-antiparticle pair, of total energy dE can exist for a time\n> dt, provided dt and dE satisfy Heisenberg\'s uncertainty principle. For\n> the time that they exist I don\'t see any reason that the particles are\n> not just as real as any other. As for observational evidence, the fact\n> that we cannot observe them is not a problem - after all try observing\n> a single quark ! We know that they are they because otherwise the\n> charge on an electron would be quite different. Also there are effects\n> which are attributed to virtal particles such as the Casimir effect\n> which are observable. I still am yet to be convinced by any argument\n> that these particles are not real.\n\nFirst, I\'d like to point out that no-one beside yourself is responsible\nfor whatever virtual things (particles or otherwise) are running around in\nyour head. Rather than challenging people to correct your misconceptions,\na better attitude would be to try to learn more about what physicists call\n"virtual particles" and then make a decision for yourself whether they are\n"real" or not.\n\nWith that in mind, let me tell you how virtual particles come up in\ncalculations. I\'m not going to tell you what "real" is, but I\'ll tell you\nhow we decide that a particle is there or not. Take some process and put\ndetectors around it. The detectors make localized measurements that tell\nyou the energy and momentum of something. You say that this something is a\nparticle. Let us not belabor the "reality" of this scenario because I\'ve\nnot even introduced virtual particles yet.\n\nNow, you\'ve got some experimental results and you want to compare them to\npredictions of your theory. If this theory happens to be say QED, you go\noff and do the calculations. How do you do these calculations? Because of\nthe complexity of the theory one must make approximations. What kind of\napproximations? Like for any problem there may be more than one\napproximation you can make. In principle, three come to mind at the\nmoment, but there could be more:\n\n1) Do some perturbative calculations that involve scribbling diagrams on\npaper with solid and wavy lines that look awful lot like photons and\nelectrons, and evaluating integrals associated with them.\n\n2) Concoct some large matrix representation of your states and operators,\nthen go to your futuristic supercomputer and make it solve some matrix\ndifferential equations.\n\n3) Write down the path integral formulation of the same problem and go off\nto another futuristic supercomputer and make it crunch some numbers to\nevaluate this integral.\n\nIf you did your calculations right in the end you get the same answer with\nall of the above. However, virtual particles only come up in method (1),\nthey are an interpretation of the calculation steps that conveniently\ninvolve drawing very suggestive diagrams. But other methods have their own\ninterpretations. In (3) you picture a particle wandering around in all\npossible paths and averaging contributions from each path you arrive at\nsomething close to the classical path with some corrections. In (2) you\nnote that as the state (wave function if you will) evolves with time it\nbecomes a superposition of states representing classically exclusive\nalternatives, but only finitely many of them since you matrix\nrepresentation is necessarily finite-dimensional.\n\nI\'m sure you\'ve at least heard of the above interpretations of\nquantum-mechanical and field-theoretical calculations. So if you start\nasking yourself about the reality of virtual particles, I think you should\nstart asking yourself whether the paths taken by electrons in the path\nintegral and the superpositions and finite dimensionality of the matrix\napproximation are real.\n\nWell, are they?\n\nIgor\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>iantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409271242.48e55ac1@posting.google.com>...
> As I said in my original e-mail if someone comes up with a convincing
> argument for why virtual particles are not real, I'm prepared to
> change my mind. Making the above statements (such as a virtual
> electron is as different to a real electron as chalk is to cheese is
> not to my mind at all convincing). As far as I know a virtual
> particle-antiparticle pair, of total energy dE can exist for a time
> dt, provided dt and dE satisfy Heisenberg's uncertainty principle. For
> the time that they exist I don't see any reason that the particles are
> not just as real as any other. As for observational evidence, the fact
> that we cannot observe them is not a problem - after all try observing
> a single quark ! We know that they are they because otherwise the
> charge on an electron would be quite different. Also there are effects
> which are attributed to virtal particles such as the Casimir effect
> which are observable. I still am yet to be convinced by any argument
> that these particles are not real.
First, I'd like to point out that no-one beside yourself is responsible
for whatever virtual things (particles or otherwise) are running around in
your head. Rather than challenging people to correct your misconceptions,
a better attitude would be to try to learn more about what physicists call
"virtual particles" and then make a decision for yourself whether they are
"real" or not.
With that in mind, let me tell you how virtual particles come up in
calculations. I'm not going to tell you what "real" is, but I'll tell you
how we decide that a particle is there or not. Take some process and put
detectors around it. The detectors make localized measurements that tell
you the energy and momentum of something. You say that this something is a
particle. Let us not belabor the "reality" of this scenario because I've
not even introduced virtual particles yet.
Now, you've got some experimental results and you want to compare them to
predictions of your theory. If this theory happens to be say QED, you go
off and do the calculations. How do you do these calculations? Because of
the complexity of the theory one must make approximations. What kind of
approximations? Like for any problem there may be more than one
approximation you can make. In principle, three come to mind at the
moment, but there could be more:
1) Do some perturbative calculations that involve scribbling diagrams on
paper with solid and wavy lines that look awful lot like photons and
electrons, and evaluating integrals associated with them.
2) Concoct some large matrix representation of your states and operators,
then go to your futuristic supercomputer and make it solve some matrix
differential equations.
3) Write down the path integral formulation of the same problem and go off
to another futuristic supercomputer and make it crunch some numbers to
evaluate this integral.
If you did your calculations right in the end you get the same answer with
all of the above. However, virtual particles only come up in method (1),
they are an interpretation of the calculation steps that conveniently
involve drawing very suggestive diagrams. But other methods have their own
interpretations. In (3) you picture a particle wandering around in all
possible paths and averaging contributions from each path you arrive at
something close to the classical path with some corrections. In (2) you
note that as the state (wave function if you will) evolves with time it
becomes a superposition of states representing classically exclusive
alternatives, but only finitely many of them since you matrix
representation is necessarily finite-dimensional.
I'm sure you've at least heard of the above interpretations of
quantum-mechanical and field-theoretical calculations. So if you start
asking yourself about the reality of virtual particles, I think you should
start asking yourself whether the paths taken by electrons in the path
integral and the superpositions and finite dimensionality of the matrix
approximation are real.
Well, are they?
Igor
Ralph Hartley
Oct5-04, 06:42 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>Igor Khavkine wrote:\n\n> So if you start\n> asking yourself about the reality of virtual particles, I think you should\n> start asking yourself whether the paths taken by electrons in the path\n> integral and the superpositions and finite dimensionality of the matrix\n> approximation are real.\n>\n> Well, are they?\n\nSo far as I know, it is possible to interpret all of those things as real.\nI\'m not so sure that you can interpret them all as real simultainiously or\nnot, but why would you want to?\n\nIn the interpretation in which virtual particles are real, they differ from\n"real" particles in only one way: they were no observed. They *could* have\nbeen, but they weren\'t.\n\nIn that interpretation saying "virtual particles can\'t be observed" is the\nsame as saying "particles that are not observed can\'t be observed," which\nis pretty obvious.\n\nRalph Hartley\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>Igor Khavkine wrote:
> So if you start
> asking yourself about the reality of virtual particles, I think you should
> start asking yourself whether the paths taken by electrons in the path
> integral and the superpositions and finite dimensionality of the matrix
> approximation are real.
>
> Well, are they?
So far as I know, it is possible to interpret all of those things as real.
I'm not so sure that you can interpret them all as real simultainiously or
not, but why would you want to?
In the interpretation in which virtual particles are real, they differ from
"real" particles in only one way: they were no observed. They *could* have
been, but they weren't.
In that interpretation saying "virtual particles can't be observed" is the
same as saying "particles that are not observed can't be observed," which
is pretty obvious.
Ralph Hartley
Igor Khavkine
Oct6-04, 08:03 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>Organization: (no organization specified)\n[ The following text is in the "UTF-8" character set. ]\n[ Your display is set for the "US-ASCII" character set. ]\n[ Some characters may be displayed incorrectly. ]\n\nOn Tue, 05 Oct 2004 11:42:09 +0000, Ralph Hartley wrote:\n\n> Igor Khavkine wrote:\n>\n>> So if you start\n>> asking yourself about the reality of virtual particles, I think you\n>> should start asking yourself whether the paths taken by electrons in the\n>> path integral and the superpositions and finite dimensionality of the\n>> matrix approximation are real.\n>>\n>> Well, are they?\n>\n> So far as I know, it is possible to interpret all of those things as real.\n> I\'m not so sure that you can interpret them all as real simultainiously or\n> not, but why would you want to?\n\nIndeed.\n\n> In the interpretation in which virtual particles are real, they differ\n> from "real" particles in only one way: they were no observed. They *could*\n> have been, but they weren\'t.\n>\n> In that interpretation saying "virtual particles can\'t be observed" is the\n> same as saying "particles that are not observed can\'t be observed," which\n> is pretty obvious.\n\nThere are many particles in the universe that are quite real in this\ninterpretation but are not observed by me. I know that you mean "can\'t be\nobserved *in principle*", but the confused masses do not seem to. That is\nwhy I think we should be equal opportunity confusers of the masses and not\ngive more prominence to interpretations of other approximation techniques.\nHopefully, in the resulting increased confusion, clarity will emerge and\npeople will realize that, although it is possible to give interpretation\nto an approximate calculation, neither one nor the other is unique.\n\nI\'m not worried about people understanding physics through such\ninterpretation, but I am worried about them assuming that there is only\none and that it is "the one real truth".\n\nIgor\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>Organization: (no organization specified)
[ The following text is in the "UTF-8" character set. ]
[ Your display is set for the "US-ASCII" character set. ]
[ Some characters may be displayed incorrectly. ]
On Tue, 05 Oct 2004 11:42:09 +0000, Ralph Hartley wrote:
> Igor Khavkine wrote:
>
>> So if you start
>> asking yourself about the reality of virtual particles, I think you
>> should start asking yourself whether the paths taken by electrons in the
>> path integral and the superpositions and finite dimensionality of the
>> matrix approximation are real.
>>
>> Well, are they?
>
> So far as I know, it is possible to interpret all of those things as real.
> I'm not so sure that you can interpret them all as real simultainiously or
> not, but why would you want to?
Indeed.
> In the interpretation in which virtual particles are real, they differ
> from "real" particles in only one way: they were no observed. They *could*
> have been, but they weren't.
>
> In that interpretation saying "virtual particles can't be observed" is the
> same as saying "particles that are not observed can't be observed," which
> is pretty obvious.
There are many particles in the universe that are quite real in this
interpretation but are not observed by me. I know that you mean "can't be
observed *in principle*", but the confused masses do not seem to. That is
why I think we should be equal opportunity confusers of the masses and not
give more prominence to interpretations of other approximation techniques.
Hopefully, in the resulting increased confusion, clarity will emerge and
people will realize that, although it is possible to give interpretation
to an approximate calculation, neither one nor the other is unique.
I'm not worried about people understanding physics through such
interpretation, but I am worried about them assuming that there is only
one and that it is "the one real truth".
Igor
Arnold Neumaier
Oct6-04, 08:03 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>Ralph Hartley wrote:\n\n> In the interpretation in which virtual particles are real, they differ from\n> "real" particles in only one way: they were no observed. They *could* have\n> been, but they weren\'t.\n\nNo. They could _not_ be observed, since observed are _only_ particles which\nare on shell. \'could be observed\' is only meaningful if you can give a\nrecipe for how to observe them if you want. But this is impossible, since\ntheir existence depends on the computational scheme used to predict\nobservations of \'real\' particles.\n\n\nArnold Neumaier\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>Ralph Hartley wrote:
> In the interpretation in which virtual particles are real, they differ from
> "real" particles in only one way: they were no observed. They *could* have
> been, but they weren't.
No. They could _not_ be observed, since observed are _only_ particles which
are on shell. 'could be observed' is only meaningful if you can give a
recipe for how to observe them if you want. But this is impossible, since
their existence depends on the computational scheme used to predict
observations of 'real' particles.
Arnold Neumaier
Ian Taylor
Oct6-04, 08:03 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>Igor Khavkine <igor.kh@gmail.com> wrote in message news:<cjs0q6\\$sv2\\$1@lfa222122.richmond.edu>...\ n> iantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409271242.48e55ac1@posting.google. com>...\n>\n> > As I said in my original e-mail if someone comes up with a convincing\n> > argument for why virtual particles are not real, I\'m prepared to\n> > change my mind. Making the above statements (such as a virtual\n> > electron is as different to a real electron as chalk is to cheese is\n> > not to my mind at all convincing). As far as I know a virtual\n> > particle-antiparticle pair, of total energy dE can exist for a time\n> > dt, provided dt and dE satisfy Heisenberg\'s uncertainty principle. For\n> > the time that they exist I don\'t see any reason that the particles are\n> > not just as real as any other. As for observational evidence, the fact\n> > that we cannot observe them is not a problem - after all try observing\n> > a single quark ! We know that they are they because otherwise the\n> > charge on an electron would be quite different. Also there are effects\n> > which are attributed to virtal particles such as the Casimir effect\n> > which are observable. I still am yet to be convinced by any argument\n> > that these particles are not real.\n>\n> First, I\'d like to point out that no-one beside yourself is responsible\n> for whatever virtual things (particles or otherwise) are running around in\n> your head. Rather than challenging people to correct your misconceptions,\n> a better attitude would be to try to learn more about what physicists call\n> "virtual particles" and then make a decision for yourself whether they are\n> "real" or not.\n>\n> With that in mind, let me tell you how virtual particles come up in\n> calculations. I\'m not going to tell you what "real" is, but I\'ll tell you\n> how we decide that a particle is there or not. Take some process and put\n> detectors around it. The detectors make localized measurements that tell\n> you the energy and momentum of something. You say that this something is a\n> particle. Let us not belabor the "reality" of this scenario because I\'ve\n> not even introduced virtual particles yet.\n>\n> Now, you\'ve got some experimental results and you want to compare them to\n> predictions of your theory. If this theory happens to be say QED, you go\n> off and do the calculations. How do you do these calculations? Because of\n> the complexity of the theory one must make approximations. What kind of\n> approximations? Like for any problem there may be more than one\n> approximation you can make. In principle, three come to mind at the\n> moment, but there could be more:\n>\n> 1) Do some perturbative calculations that involve scribbling diagrams on\n> paper with solid and wavy lines that look awful lot like photons and\n> electrons, and evaluating integrals associated with them.\n>\n> 2) Concoct some large matrix representation of your states and operators,\n> then go to your futuristic supercomputer and make it solve some matrix\n> differential equations.\n>\n> 3) Write down the path integral formulation of the same problem and go off\n> to another futuristic supercomputer and make it crunch some numbers to\n> evaluate this integral.\n>\n> If you did your calculations right in the end you get the same answer with\n> all of the above. However, virtual particles only come up in method (1),\n> they are an interpretation of the calculation steps that conveniently\n> involve drawing very suggestive diagrams. But other methods have their own\n> interpretations. In (3) you picture a particle wandering around in all\n> possible paths and averaging contributions from each path you arrive at\n> something close to the classical path with some corrections. In (2) you\n> note that as the state (wave function if you will) evolves with time it\n> becomes a superposition of states representing classically exclusive\n> alternatives, but only finitely many of them since you matrix\n> representation is necessarily finite-dimensional.\n>\n> I\'m sure you\'ve at least heard of the above interpretations of\n> quantum-mechanical and field-theoretical calculations. So if you start\n> asking yourself about the reality of virtual particles, I think you should\n> start asking yourself whether the paths taken by electrons in the path\n> integral and the superpositions and finite dimensionality of the matrix\n> approximation are real.\n>\n> Well, are they?\n>\n> Igor\n\nI\'m well aware of how to do the calculations since I have a degree in\nTheoretical Physics and a PhD in Applied Quantum Physics. Clearly\nsub-atomic "particles" are neither particles or waves. When you do\nquantum mechanical calculations on a particle basis, then you use the\nconcept of virtual particles, and I am aware that these cannot be\nobserved, but my objection to people saying that they are not real\n(and just a calculational device) is mainly based on the\nindistinguishability principle. (ie if you say a virtual electron is\ndifferent from a real electron you are saying that they are\ndistinguishable whereas I believe all electrons are\nindistinguishable).\n\nOn the other hand, if you treat the calculations on a wave-like basis,\nusing Feynmann\'s sum over histories approach, then I also believe that\nthe wave does "sample" each path - so in that sense I believe the\npaths are real.\n\nI don\'t believe we have got a good enough theory yet of quantum\nmechanics, since if there are two different ways of doing the\ncalculations, one based on a particle picture, and one based on a wave\npicture, then it seems to me as if there must be some better\n"underlying" theory, which explains why these two viewpoints hold.\n\nIan Taylor\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>Igor Khavkine <igor.kh@gmail.com> wrote in message news:<cjs0q6$sv2$1@lfa222122.richmond.edu>...
> iantaylor2uk@yahoo.co.uk (Ian Taylor) wrote in message news:<2eefbf19.0409271242.48e55ac1@posting.google.com>...
>
> > As I said in my original e-mail if someone comes up with a convincing
> > argument for why virtual particles are not real, I'm prepared to
> > change my mind. Making the above statements (such as a virtual
> > electron is as different to a real electron as chalk is to cheese is
> > not to my mind at all convincing). As far as I know a virtual
> > particle-antiparticle pair, of total energy dE can exist for a time
> > dt, provided dt and dE satisfy Heisenberg's uncertainty principle. For
> > the time that they exist I don't see any reason that the particles are
> > not just as real as any other. As for observational evidence, the fact
> > that we cannot observe them is not a problem - after all try observing
> > a single quark ! We know that they are they because otherwise the
> > charge on an electron would be quite different. Also there are effects
> > which are attributed to virtal particles such as the Casimir effect
> > which are observable. I still am yet to be convinced by any argument
> > that these particles are not real.
>
> First, I'd like to point out that no-one beside yourself is responsible
> for whatever virtual things (particles or otherwise) are running around in
> your head. Rather than challenging people to correct your misconceptions,
> a better attitude would be to try to learn more about what physicists call
> "virtual particles" and then make a decision for yourself whether they are
> "real" or not.
>
> With that in mind, let me tell you how virtual particles come up in
> calculations. I'm not going to tell you what "real" is, but I'll tell you
> how we decide that a particle is there or not. Take some process and put
> detectors around it. The detectors make localized measurements that tell
> you the energy and momentum of something. You say that this something is a
> particle. Let us not belabor the "reality" of this scenario because I've
> not even introduced virtual particles yet.
>
> Now, you've got some experimental results and you want to compare them to
> predictions of your theory. If this theory happens to be say QED, you go
> off and do the calculations. How do you do these calculations? Because of
> the complexity of the theory one must make approximations. What kind of
> approximations? Like for any problem there may be more than one
> approximation you can make. In principle, three come to mind at the
> moment, but there could be more:
>
> 1) Do some perturbative calculations that involve scribbling diagrams on
> paper with solid and wavy lines that look awful lot like photons and
> electrons, and evaluating integrals associated with them.
>
> 2) Concoct some large matrix representation of your states and operators,
> then go to your futuristic supercomputer and make it solve some matrix
> differential equations.
>
> 3) Write down the path integral formulation of the same problem and go off
> to another futuristic supercomputer and make it crunch some numbers to
> evaluate this integral.
>
> If you did your calculations right in the end you get the same answer with
> all of the above. However, virtual particles only come up in method (1),
> they are an interpretation of the calculation steps that conveniently
> involve drawing very suggestive diagrams. But other methods have their own
> interpretations. In (3) you picture a particle wandering around in all
> possible paths and averaging contributions from each path you arrive at
> something close to the classical path with some corrections. In (2) you
> note that as the state (wave function if you will) evolves with time it
> becomes a superposition of states representing classically exclusive
> alternatives, but only finitely many of them since you matrix
> representation is necessarily finite-dimensional.
>
> I'm sure you've at least heard of the above interpretations of
> quantum-mechanical and field-theoretical calculations. So if you start
> asking yourself about the reality of virtual particles, I think you should
> start asking yourself whether the paths taken by electrons in the path
> integral and the superpositions and finite dimensionality of the matrix
> approximation are real.
>
> Well, are they?
>
> Igor
I'm well aware of how to do the calculations since I have a degree in
Theoretical Physics and a PhD in Applied Quantum Physics. Clearly
sub-atomic "particles" are neither particles or waves. When you do
quantum mechanical calculations on a particle basis, then you use the
concept of virtual particles, and I am aware that these cannot be
observed, but my objection to people saying that they are not real
(and just a calculational device) is mainly based on the
indistinguishability principle. (ie if you say a virtual electron is
different from a real electron you are saying that they are
distinguishable whereas I believe all electrons are
indistinguishable).
On the other hand, if you treat the calculations on a wave-like basis,
using Feynmann's sum over histories approach, then I also believe that
the wave does "sample" each path - so in that sense I believe the
paths are real.
I don't believe we have got a good enough theory yet of quantum
mechanics, since if there are two different ways of doing the
calculations, one based on a particle picture, and one based on a wave
picture, then it seems to me as if there must be some better
"underlying" theory, which explains why these two viewpoints hold.
Ian Taylor
<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\nIgor Khavkine <igor.kh@gmail.com> wrote in message news:<cjs0q6\\$sv2\\$1@lfa222122.richmond.edu>...\ nSNIP\n>\n> With that in mind, let me tell you how virtual particles come up in\n> calculations. I\'m not going to tell you what "real" is, but I\'ll tell you\n> how we decide that a particle is there or not. Take some process and put\n> detectors around it. The detectors make localized measurements that tell\n> you the energy and momentum of something. You say that this something is a\n> particle. Let us not belabor the "reality" of this scenario because I\'ve\n> not even introduced virtual particles yet.\n>\nSNIP\n>. In principle, three come to mind at the\n> moment, but there could be more:\n>\n> 1) Do some perturbative calculations that involve scribbling diagrams on\n> paper with solid and wavy lines that look awful lot like photons and\n> electrons, and evaluating integrals associated with them.\n>\n> 2) Concoct some large matrix representation of your states and operators,\n> then go to your futuristic supercomputer and make it solve some matrix\n> differential equations.\n>\n> 3) Write down the path integral formulation of the same problem and go off\n> to another futuristic supercomputer and make it crunch some numbers to\n> evaluate this integral.\n>\nSNIP\n> So if you start\n> asking yourself about the reality of virtual particles, I think you should\n> start asking yourself whether the paths taken by electrons in the path\n> integral and the superpositions and finite dimensionality of the matrix\n> approximation are real.\n>\n> Well, are they?\n>\n> Igor\nI would answer as follows: if you put the detectors in an accelerated\nframe of reference, you will indeed observe some "virtual" particles\nas on mass-shell and real. Of course, the other two formulations will\nalso produce identical observational predictions of the events. And\neach would have their own (but rather convoluted) explanation.\n\nIn this sense, on-mass-shell particles are no more or less real than\noff-mass-shell particles.\n\nAnother example would be (in condensed matter physics), electrons with\nan effective mass in a crystal lattice, or quasiparticles in the\nFractional Quantum Hall Effect. They are all simply the easiest way of\npicturing the physics, and hence getting the insight required to push\nforward. Which to me is shorthand for saying that all Physics is\nperturbation theory, done in one\'s head, just find the "right" basis.\n\nSo to go back to the question, no, the second two methods aren\'t\n"real", because for whatever experimental situation at hand that you\nassumed, they were not the lowest-order perturbation, because you\nneeded a futuristic supercomputer to get the results. But for some\nexperimental set-ups, they may provide the lowest-order perturbation\nresults, and so they would be real for that system.\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>Igor Khavkine <igor.kh@gmail.com> wrote in message news:<cjs0q6$sv2$1@lfa222122.richmond.edu>...
SNIP
>
> With that in mind, let me tell you how virtual particles come up in
> calculations. I'm not going to tell you what "real" is, but I'll tell you
> how we decide that a particle is there or not. Take some process and put
> detectors around it. The detectors make localized measurements that tell
> you the energy and momentum of something. You say that this something is a
> particle. Let us not belabor the "reality" of this scenario because I've
> not even introduced virtual particles yet.
>
SNIP
>. In principle, three come to mind at the
> moment, but there could be more:
>
> 1) Do some perturbative calculations that involve scribbling diagrams on
> paper with solid and wavy lines that look awful lot like photons and
> electrons, and evaluating integrals associated with them.
>
> 2) Concoct some large matrix representation of your states and operators,
> then go to your futuristic supercomputer and make it solve some matrix
> differential equations.
>
> 3) Write down the path integral formulation of the same problem and go off
> to another futuristic supercomputer and make it crunch some numbers to
> evaluate this integral.
>
SNIP
> So if you start
> asking yourself about the reality of virtual particles, I think you should
> start asking yourself whether the paths taken by electrons in the path
> integral and the superpositions and finite dimensionality of the matrix
> approximation are real.
>
> Well, are they?
>
> Igor
I would answer as follows: if you put the detectors in an accelerated
frame of reference, you will indeed observe some "virtual" particles
as on mass-shell and real. Of course, the other two formulations will
also produce identical observational predictions of the events. And
each would have their own (but rather convoluted) explanation.
In this sense, on-mass-shell particles are no more or less real than
off-mass-shell particles.
Another example would be (in condensed matter physics), electrons with
an effective mass in a crystal lattice, or quasiparticles in the
Fractional Quantum Hall Effect. They are all simply the easiest way of
picturing the physics, and hence getting the insight required to push
forward. Which to me is shorthand for saying that all Physics is
perturbation theory, done in one's head, just find the "right" basis.
So to go back to the question, no, the second two methods aren't
"real", because for whatever experimental situation at hand that you
assumed, they were not the lowest-order perturbation, because you
needed a futuristic supercomputer to get the results. But for some
experimental set-ups, they may provide the lowest-order perturbation
results, and so they would be real for that system.
Igor Khavkine
Oct14-04, 11:07 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\nOn Mon, 11 Oct 2004 08:52:31 +0000, jdff wrote:\n\n>\n>\n> Igor Khavkine <igor.kh@gmail.com> wrote in message\n> news:<cjs0q6\\$sv2\\$1@lfa222122.richmond.edu>... SNIP\n>>\n>> With that in mind, let me tell you how virtual particles come up in\n>> calculations. I\'m not going to tell you what "real" is, but I\'ll tell\n>> you how we decide that a particle is there or not. Take some process and\n>> put detectors around it. The detectors make localized measurements that\n>> tell you the energy and momentum of something. You say that this\n>> something is a particle. Let us not belabor the "reality" of this\n>> scenario because I\'ve not even introduced virtual particles yet.\n>>\n> SNIP\n>>. In principle, three come to mind at the\n>> moment, but there could be more:\n>>\n>> 1) Do some perturbative calculations that involve scribbling diagrams on\n>> paper with solid and wavy lines that look awful lot like photons and\n>> electrons, and evaluating integrals associated with them.\n>>\n>> 2) Concoct some large matrix representation of your states and\n>> operators,\n>> then go to your futuristic supercomputer and make it solve some\n>> matrix differential equations.\n>>\n>> 3) Write down the path integral formulation of the same problem and go\n>> off\n>> to another futuristic supercomputer and make it crunch some numbers\n>> to evaluate this integral.\n>>\n> SNIP\n>> So if you start\n>> asking yourself about the reality of virtual particles, I think you\n>> should start asking yourself whether the paths taken by electrons in the\n>> path integral and the superpositions and finite dimensionality of the\n>> matrix approximation are real.\n>>\n>> Well, are they?\n>>\n>> Igor\n> I would answer as follows: if you put the detectors in an accelerated\n> frame of reference, you will indeed observe some "virtual" particles as on\n> mass-shell and real. Of course, the other two formulations will also\n> produce identical observational predictions of the events. And each would\n> have their own (but rather convoluted) explanation.\n>\n> In this sense, on-mass-shell particles are no more or less real than\n> off-mass-shell particles.\n\nBeauty is in the eye of the beholder. What you may find convoluted may\nseem perfectly reasonable to someone else. There are no off-mass-shell\nparticles. Finding one would violate relativity. All we have are\ninterpretations of calculations, and usually more than one interpretation\nis possible.\n\n> Another example would be (in condensed matter physics), electrons with an\n> effective mass in a crystal lattice, or quasiparticles in the Fractional\n> Quantum Hall Effect. They are all simply the easiest way of picturing the\n> physics, and hence getting the insight required to push forward. Which to\n> me is shorthand for saying that all Physics is perturbation theory, done\n> in one\'s head, just find the "right" basis.\n\nPhysics is not all perturbation theory. And an that a way to interpret\nperturbative calculations is easy does not mean that it is unique or even\npreferred. You are absolutely right that picturing physics can lead to\ninsight. But I hope you are not saying that there is only one way to\npicture a given physical phenomenon and that other ways cannot lead to\ndifferent insights.\n\n> So to go back to the question, no, the second two methods aren\'t "real",\n> because for whatever experimental situation at hand that you assumed, they\n> were not the lowest-order perturbation, because you needed a futuristic\n> supercomputer to get the results. But for some experimental set-ups, they\n> may provide the lowest-order perturbation results, and so they would be\n> real for that system.\n\nSuppose that there is a theory that depends on two small parameters. Then\nto calculate something with this theory we can do perturbation in either\nparameter. Suppose that the lowest order results for either variable agree\nwith experiment. Which one is real for you? One calculation gives say the\nleading order result in one variable and is non-perturbative in the other\nvariables, and vice versa. The fact that one calculation may require a\nsupercomputer while the other only pen and paper is irrelevant.\n\nIn my world view a calculational device does not dictate reality, but\nopinions may differ. However, if reality is defined by calculation, it is\nonly as unique as the technique of calculation, in other words it is not.\n\nIgor\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 Mon, 11 Oct 2004 08:52:31 +0000, jdff wrote:
>
>
> Igor Khavkine <igor.kh@gmail.com> wrote in message
> news:<cjs0q6$sv2$1@lfa222122.richmond.edu>... SNIP
>>
>> With that in mind, let me tell you how virtual particles come up in
>> calculations. I'm not going to tell you what "real" is, but I'll tell
>> you how we decide that a particle is there or not. Take some process and
>> put detectors around it. The detectors make localized measurements that
>> tell you the energy and momentum of something. You say that this
>> something is a particle. Let us not belabor the "reality" of this
>> scenario because I've not even introduced virtual particles yet.
>>
> SNIP
>>. In principle, three come to mind at the
>> moment, but there could be more:
>>
>> 1) Do some perturbative calculations that involve scribbling diagrams on
>> paper with solid and wavy lines that look awful lot like photons and
>> electrons, and evaluating integrals associated with them.
>>
>> 2) Concoct some large matrix representation of your states and
>> operators,
>> then go to your futuristic supercomputer and make it solve some
>> matrix differential equations.
>>
>> 3) Write down the path integral formulation of the same problem and go
>> off
>> to another futuristic supercomputer and make it crunch some numbers
>> to evaluate this integral.
>>
> SNIP
>> So if you start
>> asking yourself about the reality of virtual particles, I think you
>> should start asking yourself whether the paths taken by electrons in the
>> path integral and the superpositions and finite dimensionality of the
>> matrix approximation are real.
>>
>> Well, are they?
>>
>> Igor
> I would answer as follows: if you put the detectors in an accelerated
> frame of reference, you will indeed observe some "virtual" particles as on
> mass-shell and real. Of course, the other two formulations will also
> produce identical observational predictions of the events. And each would
> have their own (but rather convoluted) explanation.
>
> In this sense, on-mass-shell particles are no more or less real than
> off-mass-shell particles.
Beauty is in the eye of the beholder. What you may find convoluted may
seem perfectly reasonable to someone else. There are no off-mass-shell
particles. Finding one would violate relativity. All we have are
interpretations of calculations, and usually more than one interpretation
is possible.
> Another example would be (in condensed matter physics), electrons with an
> effective mass in a crystal lattice, or quasiparticles in the Fractional
> Quantum Hall Effect. They are all simply the easiest way of picturing the
> physics, and hence getting the insight required to push forward. Which to
> me is shorthand for saying that all Physics is perturbation theory, done
> in one's head, just find the "right" basis.
Physics is not all perturbation theory. And an that a way to interpret
perturbative calculations is easy does not mean that it is unique or even
preferred. You are absolutely right that picturing physics can lead to
insight. But I hope you are not saying that there is only one way to
picture a given physical phenomenon and that other ways cannot lead to
different insights.
> So to go back to the question, no, the second two methods aren't "real",
> because for whatever experimental situation at hand that you assumed, they
> were not the lowest-order perturbation, because you needed a futuristic
> supercomputer to get the results. But for some experimental set-ups, they
> may provide the lowest-order perturbation results, and so they would be
> real for that system.
Suppose that there is a theory that depends on two small parameters. Then
to calculate something with this theory we can do perturbation in either
parameter. Suppose that the lowest order results for either variable agree
with experiment. Which one is real for you? One calculation gives say the
leading order result in one variable and is non-perturbative in the other
variables, and vice versa. The fact that one calculation may require a
supercomputer while the other only pen and paper is irrelevant.
In my world view a calculational device does not dictate reality, but
opinions may differ. However, if reality is defined by calculation, it is
only as unique as the technique of calculation, in other words it is not.
Igor
Arnold Neumaier
Oct15-04, 01:55 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>\n\n\nIgor Khavkine wrote:\n\n> Physics is not all perturbation theory. And an that a way to interpret\n> perturbative calculations is easy does not mean that it is unique or even\n> preferred. You are absolutely right that picturing physics can lead to\n> insight. But I hope you are not saying that there is only one way to\n> picture a given physical phenomenon and that other ways cannot lead to\n> different insights.\n\nAnd, as important: Picturing physics can lead to wrong insight.\nThis is the case if one takes the metapher of virtual particles too far.\n\n\nArnold Neumaier\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>Igor Khavkine wrote:
> Physics is not all perturbation theory. And an that a way to interpret
> perturbative calculations is easy does not mean that it is unique or even
> preferred. You are absolutely right that picturing physics can lead to
> insight. But I hope you are not saying that there is only one way to
> picture a given physical phenomenon and that other ways cannot lead to
> different insights.
And, as important: Picturing physics can lead to wrong insight.
This is the case if one takes the metapher of virtual particles too far.
Arnold Neumaier
vBulletin® v3.8.7, Copyright ©2000-2012, vBulletin Solutions, Inc.