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FrediFizzx
Apr7-04, 08:50 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resize=yes,status=no,wi dth=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>"Patrick Van Esch" <vanesch@ill.fr> wrote in message\nnews:c23e597b.0403300428.7371a015@posting .google.com...\n\n| For me, a few reasons to be cautious with virtual particles are:\n|\n| * their bizarre mass (imaginary in some cases)\n| * their bizarre velocity\n| * their timelessness (when in loops)\n| * the fact that you cannot make them have a detector say "click".\n|\n| All the above things are, to me, *defining* properties of what I\'d\n| call a particle, and a virtual one fails the test on all of them.\n\nHmmm? In the SLAC E144 experiment that involved pair production from light\non light, wasn\'t the gamma photon from the electron virtual? And wasn\'t the\nemitting electron seen to recoil? IOW, we do see real recoils from virtual\nparticles interacting with real matter. This tends to make me think that\nvirtual particles are real enough that they can transfer momentum.\n\nFrediFizzx\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">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Patrick Van Esch" <vanesch@ill.fr> wrote in message
news:c23e597b.0403300428.7371a015@posting.google.c om...

| For me, a few reasons to be cautious with virtual particles are:
|
| * their bizarre mass (imaginary in some cases)
| * their bizarre velocity
| * their timelessness (when in loops)
| * the fact that you cannot make them have a detector say "click".
|
| All the above things are, to me, *defining* properties of what I'd
| call a particle, and a virtual one fails the test on all of them.

Hmmm? In the SLAC E144 experiment that involved pair production from light
on light, wasn't the \gamma photon from the electron virtual? And wasn't the
emitting electron seen to recoil? IOW, we do see real recoils from virtual
particles interacting with real matter. This tends to make me think that
virtual particles are real enough that they can transfer momentum.

FrediFizzx

greywolf42
Apr7-04, 09:22 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>FrediFizzx &lt;fredifizzx@hotmail.com&gt; wrote in message\nnews:c4nq12\\$2ki7vd\\$1@ID-185976.news.uni-berlin.de...\n&gt; "Patrick Van Esch" &lt;vanesch@ill.fr&gt; wrote in message\n&gt; news:c23e597b.0403300428.7371a015@posting.google.c om...\n&gt;\n&gt; | For me, a few reasons to be cautious with virtual particles are:\n&gt; |\n&gt; | * their bizarre mass (imaginary in some cases)\n&gt; | * their bizarre velocity\n&gt; | * their timelessness (when in loops)\n&gt; | * the fact that you cannot make them have a detector say "click".\n&gt; |\n&gt; | All the above things are, to me, *defining* properties of what I\'d\n&gt; | call a particle, and a virtual one fails the test on all of them.\n&gt;\n&gt; Hmmm? In the SLAC E144 experiment that involved pair production from\nlight\n&gt; on light, wasn\'t the gamma photon from the electron virtual? And wasn\'t\nthe\n&gt; emitting electron seen to recoil? IOW, we do see real recoils from\nvirtual\n&gt; particles interacting with real matter. This tends to make me think that\n&gt; virtual particles are real enough that they can transfer momentum.\n\nOr, it can simply mean that this was not a light-light scattering (as QED\ntheory would have it). This could simply have been a photon-electron\ninteraction. AFAIK, experimental pair production requires the presence of a\n(charged) matter particle.\n\n--\ngreywolf42\nubi dubium ibi libertas\n{remove planet for return 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">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>FrediFizzx <fredifizzx@hotmail.com> wrote in message
news:c4nq12$2ki7vd$1@ID-185976.news.uni-berlin.de...
> "Patrick Van Esch" <vanesch@ill.fr> wrote in message
> news:c23e597b.0403300428.7371a015@posting.google.c om...
>
> | For me, a few reasons to be cautious with virtual particles are:
> |
> | * their bizarre mass (imaginary in some cases)
> | * their bizarre velocity
> | * their timelessness (when in loops)
> | * the fact that you cannot make them have a detector say "click".
> |
> | All the above things are, to me, *defining* properties of what I'd
> | call a particle, and a virtual one fails the test on all of them.
>
> Hmmm? In the SLAC E144 experiment that involved pair production from
light
> on light, wasn't the \gamma photon from the electron virtual? And wasn't
the
> emitting electron seen to recoil? IOW, we do see real recoils from
virtual
> particles interacting with real matter. This tends to make me think that
> virtual particles are real enough that they can transfer momentum.

Or, it can simply mean that this was not a light-light scattering (as QED
theory would have it). This could simply have been a photon-electron
interaction. AFAIK, experimental pair production requires the presence of a
(charged) matter particle.

--
greywolf42
ubi dubium ibi libertas
{remove planet for return e-mail}