View Full Version : what's anti-C?
<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>\nHi,\n\nI am brand new to this group but have been wondering about the following two\nquestions.\n\n1) Since every particle seems to have an anti-particle, does photon have it\nas well? If no, why not? If yes, what happens when they meet each other?\n\n2) This is related to question 1. I understand that anti-matter was first\nconjectured from an observation that matters in quantum equations always\nappear in pairs (m square) and "-m" may mean something. So, what does "-c"\nmean in E=mc^2?\n\nThanks,\n- Ming\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>Hi,
I am brand new to this group but have been wondering about the following two
questions.
1) Since every particle seems to have an anti-particle, does photon have it
as well? If no, why not? If yes, what happens when they meet each other?
2) This is related to question 1. I understand that anti-matter was first
conjectured from an observation that matters in quantum equations always
appear in pairs (m square) and "-m" may mean something. So, what does "-c"
mean in E=mc^2?
Thanks,
- Ming
Uncle Al
Aug23-04, 07:18 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>mqdeng wrote:\n>\n> Hi,\n>\n> I am brand new to this group but have been wondering about the following two\n> questions.\n>\n> 1) Since every particle seems to have an anti-particle, does photon have it\n> as well? If no, why not? If yes, what happens when they meet each other?\n\nNeutral particles can be their own antiparticles (photons), or\nnot (neutrons). It depends on internal structure.\n\n> 2) This is related to question 1. I understand that anti-matter was first\n> conjectured from an observation that matters in quantum equations always\n> appear in pairs (m square) and "-m" may mean something. So, what does "-c"\n> mean in E=mc^2?\n\nThe photons are going the other way. "8^>)\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</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>mqdeng wrote:
>
> Hi,
>
> I am brand new to this group but have been wondering about the following two
> questions.
>
> 1) Since every particle seems to have an anti-particle, does photon have it
> as well? If no, why not? If yes, what happens when they meet each other?
Neutral particles can be their own antiparticles (photons), or
not (neutrons). It depends on internal structure.
> 2) This is related to question 1. I understand that anti-matter was first
> conjectured from an observation that matters in quantum equations always
> appear in pairs (m square) and "-m" may mean something. So, what does "-c"
> mean in E=mc^2?
The photons are going the other way. "8^>)
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
<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> mqdeng wrote:\n>>\n>> Hi,\n>>\n>> I am brand new to this group but have been wondering about the following\n>> two questions.\n>>\n>> 1) Since every particle seems to have an anti-particle, does photon have\n>> it as well? If no, why not? If yes, what happens when they meet each\n>> other?\n>\n> Neutral particles can be their own antiparticles (photons), or\n> not (neutrons). It depends on internal structure.\n\nA neutrino is _not_ neutral and therefore it\'s not its own anti-particle.\nThere are more charges than the electric charge. The neutrino is insensitve\nto the electromagnetic force, but sensitive to the weak force.\n\nbest,\nJeroen\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:
> mqdeng wrote:
>>
>> Hi,
>>
>> I am brand new to this group but have been wondering about the following
>> two questions.
>>
>> 1) Since every particle seems to have an anti-particle, does photon have
>> it as well? If no, why not? If yes, what happens when they meet each
>> other?
>
> Neutral particles can be their own antiparticles (photons), or
> not (neutrons). It depends on internal structure.
A neutrino is _not_ neutral and therefore it's not its own anti-particle.
There are more charges than the electric charge. The neutrino is insensitve
to the electromagnetic force, but sensitive to the weak force.
best,
Jeroen
Marcus Wellpoth
Aug24-04, 03:23 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>mqdeng wrote:\n\n>\n\n> Hi,\n>\n> I am brand new to this group but have been wondering about the following\n> two questions.\n>\n\n\n> 2) This is related to question 1. I understand that anti-matter was first\n> conjectured from an observation that matters in quantum equations always\n> appear in pairs (m square) and "-m" may mean something. So, what does "-c"\n> mean in E=mc^2?\n>\n> Thanks,\n> - Ming\n-------------------------------------------------------------------------------------\nThe positron was introduced because the energy eigenvalues of the Dirac\noperator are twofold degenerated. E_n = n E_p , n = +/-, E_p=(c^2p^2 +\nm_e^2c^4)^0.5 .\nTo see how to get E=mc^2 we will use the following approach:\nF*v= d/dt (mc^2/(1-v^2/c^2)^0.5) = d/dt T\nSo we get T = mc^2/(1-v^2/c^2)^0.5.\nWe will do an expansion T = mc^2 + (1/2)mv^2 + (3/8)m v^4/c^2 + ........\nFor v << c this will reduce to mc^2 + (1/2)mv^2.\nNow we identify mc^2 with the rest energy of the considered mass\nmw\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>mqdeng wrote:
>
> Hi,
>
> I am brand new to this group but have been wondering about the following
> two questions.
>
> 2) This is related to question 1. I understand that anti-matter was first
> conjectured from an observation that matters in quantum equations always
> appear in pairs (m square) and "-m" may mean something. So, what does "-c"
> mean in E=mc^2?
>
> Thanks,
> - Ming
-------------------------------------------------------------------------------------
The positron was introduced because the energy eigenvalues of the Dirac
operator are twofold degenerated. E_n = n E_p , n = +/-, E_p=(c^{2p}^2 +m_e^2c^4)^0.5 .
To see how to get E=mc^2 we will use the following approach:
F*v= d/dt (mc^2/(1-v^2/c^2)^0.5) = d/dt T
So we get T = mc^2/(1-v^2/c^2)^0.5.
We will do an expansion T = mc^2 + (1/2)mv^2 + (3/8)m v^4/c^2 + ........
For v << c this will reduce to mc^2 + (1/2)mv^2.
Now we identify mc^2 with the rest energy of the considered mass
mw
Arnold Neumaier
Aug24-04, 04:57 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>mqdeng wrote:\n> Hi,\n>\n> I am brand new to this group but have been wondering about the following two\n> questions.\n>\n> 1) Since every particle seems to have an anti-particle, does photon have it\n> as well? If no, why not? If yes, what happens when they meet each other?\n\nYes, it is its own antiparticle. When two high energy photons meet,\nthey can in principle create electron-positirons pairs and other stuff,\njust as an electron and a positron can annihilate into two photons.\nIn each case, the probabilities are computable as certain S-matrix\nelements.\n\n\n> 2) This is related to question 1. I understand that anti-matter was first\n> conjectured from an observation that matters in quantum equations always\n> appear in pairs (m square) and "-m" may mean something. So, what does "-c"\n> mean in E=mc^2?\n\nThis sounds like nonsense.\n\nE=mc^2 is a relation of special relativity, known long before quantum\ntheory and antimatter were born. c= speed of light.\n\nAntimatter was discovered experimentally 1932 by\nAnderson, around the same time when Dirac had his equation which \'predicted\'\npositrons (though Dirac didn\'t recognize it at first).\n\nThe relation is that an electron-positron pair (mass m+m=2m) generates\nupon annihilation radiation with energy E=2mc^2.\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>mqdeng wrote:
> Hi,
>
> I am brand new to this group but have been wondering about the following two
> questions.
>
> 1) Since every particle seems to have an anti-particle, does photon have it
> as well? If no, why not? If yes, what happens when they meet each other?
Yes, it is its own antiparticle. When two high energy photons meet,
they can in principle create electron-positirons pairs and other stuff,
just as an electron and a positron can annihilate into two photons.
In each case, the probabilities are computable as certain S-matrix
elements.
> 2) This is related to question 1. I understand that anti-matter was first
> conjectured from an observation that matters in quantum equations always
> appear in pairs (m square) and "-m" may mean something. So, what does "-c"
> mean in E=mc^2?
This sounds like nonsense.
E=mc^2 is a relation of special relativity, known long before quantum
theory and antimatter were born. c= speed of light.
Antimatter was discovered experimentally 1932 by
Anderson, around the same time when Dirac had his equation which 'predicted'
positrons (though Dirac didn't recognize it at first).
The relation is that an electron-positron pair (mass m+m=2m) generates
upon annihilation radiation with energy E=2mc^2.
Arnold Neumaier
Arnold Neumaier
Aug24-04, 04:57 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>Uncle Al wrote:\n> mqdeng wrote:\n>\n>>1) Since every particle seems to have an anti-particle, does photon have it\n>>as well? If no, why not? If yes, what happens when they meet each other?\n>\n> Neutral particles can be their own antiparticles (photons), or\n> not (neutrons). It depends on internal structure.\n\nNot quite. Both photons and neutrinos are neutral and structureless.\nIt depends on nature (experimentally) or (formally) on the form of the\nfield (real or complex). Photons correspond to Hermitian field operators,\nneutrinos to complex ones.\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>Uncle Al wrote:
> mqdeng wrote:
>
>>1) Since every particle seems to have an anti-particle, does photon have it
>>as well? If no, why not? If yes, what happens when they meet each other?
>
> Neutral particles can be their own antiparticles (photons), or
> not (neutrons). It depends on internal structure.
Not quite. Both photons and neutrinos are neutral and structureless.
It depends on nature (experimentally) or (formally) on the form of the
field (real or complex). Photons correspond to Hermitian field operators,
neutrinos to complex ones.
Arnold Neumaier
<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>"Uncle Al" <UncleAl0@hate.spam.net> wrote in message\nnews:4129E007.EAF2A75D@hate.spam.net...\n > mqdeng wrote:\n> >\n> > Hi,\n> >\n> > I am brand new to this group but have been wondering about the following\ntwo\n> > questions.\n> >\n> > 1) Since every particle seems to have an anti-particle, does photon have\nit\n> > as well? If no, why not? If yes, what happens when they meet each other?\n>\n> Neutral particles can be their own antiparticles (photons), or\n> not (neutrons). It depends on internal structure.\n\nThis is sort of arbitaray interpretation of the m^2. Some suggested\nanti-photon carries "coldness", travels in "reverse of time", etc. But I\nstill wonder what their annihilation produces. For non-photon particles, I\nunderstand the result of annihilation is a photon. But this wouldn\'t seem to\nhold for photon/anti-photon (my intuition).\n\n- Ming\n>\n> > 2) This is related to question 1. I understand that anti-matter was\nfirst\n> > conjectured from an observation that matters in quantum equations always\n> > appear in pairs (m square) and "-m" may mean something. So, what does\n"-c"\n> > mean in E=mc^2?\n>\n> The photons are going the other way. "8^>)\n>\n> --\n> Uncle Al\n> http://www.mazepath.com/uncleal/\n> (Toxic URL! Unsafe for children and most mammals)\n> http://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>"Uncle Al" <UncleAl0@hate.spam.net> wrote in message
news:4129E007.EAF2A75D@hate.spam.net...
> mqdeng wrote:
> >
> > Hi,
> >
> > I am brand new to this group but have been wondering about the following
two
> > questions.
> >
> > 1) Since every particle seems to have an anti-particle, does photon have
it
> > as well? If no, why not? If yes, what happens when they meet each other?
>
> Neutral particles can be their own antiparticles (photons), or
> not (neutrons). It depends on internal structure.
This is sort of arbitaray interpretation of the m^2. Some suggested
anti-photon carries "coldness", travels in "reverse of time", etc. But I
still wonder what their annihilation produces. For non-photon particles, I
understand the result of annihilation is a photon. But this wouldn't seem to
hold for photon/anti-photon (my intuition).
- Ming
>
> > 2) This is related to question 1. I understand that anti-matter was
first
> > conjectured from an observation that matters in quantum equations always
> > appear in pairs (m square) and "-m" may mean something. So, what does
"-c"
> > mean in E=mc^2?
>
> The photons are going the other way. "8^>)
>
> --
> Uncle Al
> http://www.mazepath.com/uncleal/
> (Toxic URL! Unsafe for children and most mammals)
> http://www.mazepath.com/uncleal/qz.pdf
Mark Palenik
Aug25-04, 02:46 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>"mqdeng" <mqdeng@yahoo.com> wrote in message\nnews:1093325283.140597@sj-nntpcache-3...\n> "Uncle Al" <UncleAl0@hate.spam.net> wrote in message\n> news:4129E007.EAF2A75D@hate.spam.net...\n> > mqdeng wrote:\n> > >\n> > > Hi,\n> > >\n> > > I am brand new to this group but have been wondering about the\nfollowing\n> two\n> > > questions.\n> > >\n> > > 1) Since every particle seems to have an anti-particle, does photon\nhave\n> it\n> > > as well? If no, why not? If yes, what happens when they meet each\nother?\n> >\n> > Neutral particles can be their own antiparticles (photons), or\n> > not (neutrons). It depends on internal structure.\n>\n> This is sort of arbitaray interpretation of the m^2. Some suggested\n> anti-photon carries "coldness", travels in "reverse of time", etc. But I\n> still wonder what their annihilation produces. For non-photon particles, I\n> understand the result of annihilation is a photon. But this wouldn\'t seem\nto\n> hold for photon/anti-photon (my intuition).\n>\n> - Ming\n\nWoah, who suggests that the anti-photin carries "coldness" and travels in\n"reverse of time"? The photon is its own anti-particle, and although if you\nchose to look at it in a time reversed manner, you could say it carries\n"coldness", which while a very imprecise term, isn\'t really that much worse\nthan "negative energy", under the circumstances, there\'s absolutely no\nreason to say that some photons are time reversed negative energy and some\nare not. Any two photons that collide will produce the interaction of a\nparticle and antiparticle.\n\nThat being said, I don\'t know exactly what it would produce, since I\'m only\na physics undergrad, but my guess is that it could either produce virtual\nparticle pairs, or two photons, depending on the circumstances.\n\nInterestingly enough, I learned in a class on classical mechanics last year\nthat a single photon can occassionally produce an electron/positron pair,\nbut only if there\'s something else present to lend some momentum. I don\'t\nremember under what circumstances you will get conservation of energy and\nmomentum, since it wasn\'t an important part of the class, but I do remember\nnot getting conserved energy and momentum with just a single photon in the\nsystem, which was the point of the problem.\n\nSorry if that last paragraph was a bit off topic.\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>"mqdeng" <mqdeng@yahoo.com> wrote in message
news:1093325283.140597@sj-nntpcache-3...
> "Uncle Al" <UncleAl0@hate.spam.net> wrote in message
> news:4129E007.EAF2A75D@hate.spam.net...
> > mqdeng wrote:
> > >
> > > Hi,
> > >
> > > I am brand new to this group but have been wondering about the
following
> two
> > > questions.
> > >
> > > 1) Since every particle seems to have an anti-particle, does photon
have
> it
> > > as well? If no, why not? If yes, what happens when they meet each
other?
> >
> > Neutral particles can be their own antiparticles (photons), or
> > not (neutrons). It depends on internal structure.
>
> This is sort of arbitaray interpretation of the m^2. Some suggested
> anti-photon carries "coldness", travels in "reverse of time", etc. But I
> still wonder what their annihilation produces. For non-photon particles, I
> understand the result of annihilation is a photon. But this wouldn't seem
to
> hold for photon/anti-photon (my intuition).
>
> - Ming
Woah, who suggests that the anti-photin carries "coldness" and travels in
"reverse of time"? The photon is its own anti-particle, and although if you
chose to look at it in a time reversed manner, you could say it carries
"coldness", which while a very imprecise term, isn't really that much worse
than "negative energy", under the circumstances, there's absolutely no
reason to say that some photons are time reversed negative energy and some
are not. Any two photons that collide will produce the interaction of a
particle and antiparticle.
That being said, I don't know exactly what it would produce, since I'm only
a physics undergrad, but my guess is that it could either produce virtual
particle pairs, or two photons, depending on the circumstances.
Interestingly enough, I learned in a class on classical mechanics last year
that a single photon can occassionally produce an electron/positron pair,
but only if there's something else present to lend some momentum. I don't
remember under what circumstances you will get conservation of energy and
momentum, since it wasn't an important part of the class, but I do remember
not getting conserved energy and momentum with just a single photon in the
system, which was the point of the problem.
Sorry if that last paragraph was a bit off topic.
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