View Full Version : Casimir Effect inside a Faraday Cage
vernonner3voltazim
Oct19-04, 03:29 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\nOver in another Thread I\'ve been involved in a discussion\nabout the Casimir Effect. I\'m hoping that posting a\nQuestion here will help resolve the issue. Thanks in\nadvance!\n\nAs you probably know, the Casimir effect involves two\nconductive plates placed parallel and very close together.\nA small force is observed, which tends to push the plates\neven closer together. According to this link:\nhttp://math.ucr.edu/home/baez/physics/Quantum/casimir.html\nthe standard explanation for the presence of that force\ninvolves virtual photons in the vacuum. The above-\nmentioned discussion concerns the effect of ordinary Real\nphotons upon the plates. We are, after all, awash in a\nsea of Real photons of just about all the longer\nwavelengths, due to broadcasts around the globe (among\nother things). Obviously they should bounce off the\nplates and contribute to the Casimir Effect. Possibly\nthey could explain ALL the Casimir Effect, and then the\nstandard explanation would likely be erroneous.\n\nSo, has the experiment ever been performed inside a\nFaraday Cage (a metal box, preferably with no openings),\nso that all Real photons would be exluded from the\nvicinity of the two plates? Then, if the Effect occurs,\nonly the standard view would explain it. If not, then\nthe standard view perhaps should be considered faulty.\nEither result would conclude the above-mentioned\ndiscussion.\n\nThanks again!\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>Over in another Thread I've been involved in a discussion
about the Casimir Effect. I'm hoping that posting a
Question here will help resolve the issue. Thanks in
advance!
As you probably know, the Casimir effect involves two
conductive plates placed parallel and very close together.
A small force is observed, which tends to push the plates
even closer together. According to this link:
http://math.ucr.edu/home/baez/physics/Quantum/casimir.html
the standard explanation for the presence of that force
involves virtual photons in the vacuum. The above-
mentioned discussion concerns the effect of ordinary Real
photons upon the plates. We are, after all, awash in a
sea of Real photons of just about all the longer
wavelengths, due to broadcasts around the globe (among
other things). Obviously they should bounce off the
plates and contribute to the Casimir Effect. Possibly
they could explain ALL the Casimir Effect, and then the
standard explanation would likely be erroneous.
So, has the experiment ever been performed inside a
Faraday Cage (a metal box, preferably with no openings),
so that all Real photons would be exluded from the
vicinity of the two plates? Then, if the Effect occurs,
only the standard view would explain it. If not, then
the standard view perhaps should be considered faulty.
Either result would conclude the above-mentioned
discussion.
Thanks again!
vernonner3voltazim
Oct21-04, 02:47 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 <UncleAl0@hate.spam.net> wrote:\n> vernonner3voltazim wrote:\n> >\n> > So, has the experiment ever been performed inside a\n> > Faraday Cage (a metal box, preferably with no openings),\n> > so that all Real photons would be exluded from the\n> > vicinity of the two plates? Then, if the Effect occurs,\n> > only the standard view would explain it. If not, then\n> > the standard view perhaps should be considered faulty.\n> > Either result would conclude the above-mentioned\n> > discussion.\n>\n> The light pressure of real photons does not vary as\n> the inverse cube of the Casmir etalon spacing. It\n> is constant and calculable. The numerical aperture\n> of the Casmir gap is negligably small.\n\nYes, BUT: We are describing an effect of light pressure\non BOTH sides of BOTH plates. When there is room for the\nphotons to fit between the plates, the light pressure is\nbalanced and there is no force. When there is little\nroom, we can compute a force that results from the\nimbalance (more photons on the outside rather than\nin-between the plates), and this imbalance increases as\nmore and more sizes of photons are excluded from between\nthe ever-closer plates. EITHER Real or Virtual.\n\nNow personally I think that the quantity of Real photons\npressing on the plates is far too insufficient to\nexplain the observed force (I favor the standard\nexplanation). But to "win" the discussion previously\nmentioned, I\'d like to be sure that NO Real photons\ncan be involved in a Casimir Test. Thus my question\nabout it ever having been performed inside a solid\nmetal Faraday Cage. So, HAS it been done? Thanks!\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:
> vernonner3voltazim wrote:
> >
> > So, has the experiment ever been performed inside a
> > Faraday Cage (a metal box, preferably with no openings),
> > so that all Real photons would be exluded from the
> > vicinity of the two plates? Then, if the Effect occurs,
> > only the standard view would explain it. If not, then
> > the standard view perhaps should be considered faulty.
> > Either result would conclude the above-mentioned
> > discussion.
>
> The light pressure of real photons does not vary as
> the inverse cube of the Casmir etalon spacing. It
> is constant and calculable. The numerical aperture
> of the Casmir gap is negligably small.
Yes, BUT: We are describing an effect of light pressure
on BOTH sides of BOTH plates. When there is room for the
photons to fit between the plates, the light pressure is
balanced and there is no force. When there is little
room, we can compute a force that results from the
imbalance (more photons on the outside rather than
in-between the plates), and this imbalance increases as
more and more sizes of photons are excluded from between
the ever-closer plates. EITHER Real or Virtual.
Now personally I think that the quantity of Real photons
pressing on the plates is far too insufficient to
explain the observed force (I favor the standard
explanation). But to "win" the discussion previously
mentioned, I'd like to be sure that NO Real photons
can be involved in a Casimir Test. Thus my question
about it ever having been performed inside a solid
metal Faraday Cage. So, HAS it been done? Thanks!
Patrick Van Esch
Oct22-04, 12:01 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\nvnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0410200705.77402cf4@posting.google. com>...\n> Uncle Al <UncleAl0@hate.spam.net> wrote:\n> > vernonner3voltazim wrote:\n> > >\n> > > So, has the experiment ever been performed inside a\n> > > Faraday Cage (a metal box, preferably with no openings),\n\nAlthough I don\'t know, I\'d think that it has. After all, the effect\nis very tiny, so all related electronics is extremely sensitive. If\nyou\'d have electromagnetic interference from outside, I\'m sure the\napparatus wouldn\'t work. The first thing you do when you work with\nvery sensitive systems is to put them in a Faraday cage, so my guess\nis that this is done.\n\ncheers,\nPatrick.\n\nPS: have a look at an experimental paper such as:\nhttp://fr.arxiv.org/PS_cache/quant-ph/pdf/0306/0306136.pdf\n\nI\'m pretty sure this has been done inside a metal box.\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>vnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0410200705.77402cf4@posting.google.com>...
> Uncle Al <UncleAl0@hate.spam.net> wrote:
> > vernonner3voltazim wrote:
> > >
> > > So, has the experiment ever been performed inside a
> > > Faraday Cage (a metal box, preferably with no openings),
Although I don't know, I'd think that it has. After all, the effect
is very tiny, so all related electronics is extremely sensitive. If
you'd have electromagnetic interference from outside, I'm sure the
apparatus wouldn't work. The first thing you do when you work with
very sensitive systems is to put them in a Faraday cage, so my guess
is that this is done.
cheers,
Patrick.
PS: have a look at an experimental paper such as:
http://fr.arxiv.org/PS_cache/quant-ph/pdf/0306/0306136.pdf
I'm pretty sure this has been done inside a metal box.
Norm Dresner
Oct22-04, 12:40 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"vernonner3voltazim" <vnemitz@pinn.net> wrote in message\nnews:42336979.0410200705.77402cf4@posting .google.com...\n>\n>\n>\n> Now personally I think that the quantity of Real photons\n> pressing on the plates is far too insufficient to\n> explain the observed force (I favor the standard\n> explanation). But to "win" the discussion previously\n> mentioned, I\'d like to be sure that NO Real photons\n> can be involved in a Casimir Test. Thus my question\n> about it ever having been performed inside a solid\n> metal Faraday Cage. So, HAS it been done? Thanks!\n\nEven within a Faraday cage each of the plates and the walls of the cage will\nradiate in the infrared as (or close to) black body radiation. Unless\nyou\'re going to chill the apparatus down to very close to 0K, you\'re not\ngoing to exclude real photons from any box.\n\nNorm\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>"vernonner3voltazim" <vnemitz@pinn.net> wrote in message
news:42336979.0410200705.77402cf4@posting.google.c om...
>
>
>
> Now personally I think that the quantity of Real photons
> pressing on the plates is far too insufficient to
> explain the observed force (I favor the standard
> explanation). But to "win" the discussion previously
> mentioned, I'd like to be sure that NO Real photons
> can be involved in a Casimir Test. Thus my question
> about it ever having been performed inside a solid
> metal Faraday Cage. So, HAS it been done? Thanks!
Even within a Faraday cage each of the plates and the walls of the cage will
radiate in the infrared as (or close to) black body radiation. Unless
you're going to chill the apparatus down to very close to 0K, you're not
going to exclude real photons from any box.
Norm
lalbatros
Oct22-04, 12:40 PM
Hello
You are right to say that we live in a sea of electromagnetic radiation. And these radiations should contribute to the pressure on the plates. However, if the Faraday cage is in the dark, only the vacuum fluctuations and the black-body radiations will remain.
Considering the first formula in the Baez paper (http://math.ucr.edu/home/baez/physics/Quantum/casimir.html) I guess that black-body radiations will be negligible if the gap is made small enough (L^-4 dependence). Indeed, once the complete BBR is cut-off in between the plates, the pressure due to BBR will be indepedent of L. And then, the vacuum effect can be made larger that the BBR effect. It would be interresting to evaluate this blackbody pressure effect.
Now what remains to be done, is to understand the formula given by Baez. I did not read about that. But I can guess that the difference with BBR is that vacuum fluctuations (outside the gap) have a 'constant' spectrum. All modes are populated whatever small the wavelength is. Actually this is a UV catastrophy! Usually, the pressure due to vacuum fluctuations is not observed. The Casimir experiment however reveals it. It is nice.
I now ask myself if it makes sense that the pressure tends to the infinity when the gap tends to zero. I think that the formula is only valid as long as the gap is larger than the interatomic distances or something like that. Below, the radiations will not be shielded anymore by the plates.
It would be quite interresting to post here the basic data on radiation pressures due to a radio emitter, the BBR, the vaccum radiations. And also maybe some links to the theory and the experiments.
Thanks for your post. Maybe I will find some time to think about that. This pressure, finally, is not virtual, and it is the root of quantum.
Michel
lalbatros
Oct22-04, 12:42 PM
I add two interresting links:
http://physicsweb.org/articles/world/15/9/6
http://arxiv.org/PS_cache/quant-ph/pdf/0106/0106045.pdf
Uncle Al
Oct25-04, 08:10 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\nvernonner3voltazim wrote:\n>\n> Uncle Al <UncleAl0@hate.spam.net> wrote:\n> > vernonner3voltazim wrote:\n> > >\n> > > So, has the experiment ever been performed inside a\n> > > Faraday Cage (a metal box, preferably with no openings),\n> > > so that all Real photons would be exluded from the\n> > > vicinity of the two plates? Then, if the Effect occurs,\n> > > only the standard view would explain it. If not, then\n> > > the standard view perhaps should be considered faulty.\n> > > Either result would conclude the above-mentioned\n> > > discussion.\n> >\n> > The light pressure of real photons does not vary as\n> > the inverse cube of the Casmir etalon spacing. It\n> > is constant and calculable. The numerical aperture\n> > of the Casmir gap is negligably small.\n>\n> Yes, BUT: We are describing an effect of light pressure\n> on BOTH sides of BOTH plates. When there is room for the\n> photons to fit between the plates, the light pressure is\n> balanced and there is no force. When there is little\n> room, we can compute a force that results from the\n> imbalance (more photons on the outside rather than\n> in-between the plates), and this imbalance increases as\n> more and more sizes of photons are excluded from between\n> the ever-closer plates. EITHER Real or Virtual.\n\nThe external area of the plates is constant. Calculate the varying\nnumerical aperture of the varying gap and answer your own question.\nCompare the perimeter/area ratios for circles, squares and\nrectangles. Why is the Casimir effect not dependent upon a shape\nfactor (compactness, re laser ring gyros)?\n\n> Now personally I think that the quantity of Real photons\n> pressing on the plates is far too insufficient to\n> explain the observed force (I favor the standard\n> explanation). But to "win" the discussion previously\n> mentioned, I\'d like to be sure that NO Real photons\n> can be involved in a Casimir Test. Thus my question\n> about it ever having been performed inside a solid\n> metal Faraday Cage. So, HAS it been done? Thanks!\n\nThe point of good physics is that the results of calculation are\nindistinguishable from experimental results. Since your proposal\ncreates contradictions with both observed fact and calculation -\nqualitative and quantitative - it is wrong.\n\nHow would you construct a "Faraday cage" to meet your specs? The\netalon gaps used to make measurements are typically a few thousand nm\n(IR) to optical gaps. Do the run in ambient light vs. darkness or\nwith varying temp - some of them must deviate. Your argument is not\nweak, it is empirically dead. (Did you ever consider that the\nmeasurement region is within shielding to exclude EM, magnetic, and\nother extraneous inteferences?)\n\nhttp://www.mazepath.com/uncleal/casimir3.htm\n\nBottom line: The Casimir effect at very small gaps cannot be\ndistinguishable from ordinary lattice forces or anomalous /_\\H of\nformations would be seen assembling or disassembling a lattice (e.g.\ngraphite, boron nitride, heavy metal chalcogenides, smectite clays,\nzirconium phosphate and phosphonates, micas, or any other lamellar\nsolids as extreme cases). The Casimir effect obeys standard physics.\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>vernonner3voltazim wrote:
>
> Uncle Al <UncleAl0@hate.spam.net> wrote:
> > vernonner3voltazim wrote:
> > >
> > > So, has the experiment ever been performed inside a
> > > Faraday Cage (a metal box, preferably with no openings),
> > > so that all Real photons would be exluded from the
> > > vicinity of the two plates? Then, if the Effect occurs,
> > > only the standard view would explain it. If not, then
> > > the standard view perhaps should be considered faulty.
> > > Either result would conclude the above-mentioned
> > > discussion.
> >
> > The light pressure of real photons does not vary as
> > the inverse cube of the Casmir etalon spacing. It
> > is constant and calculable. The numerical aperture
> > of the Casmir gap is negligably small.
>
> Yes, BUT: We are describing an effect of light pressure
> on BOTH sides of BOTH plates. When there is room for the
> photons to fit between the plates, the light pressure is
> balanced and there is no force. When there is little
> room, we can compute a force that results from the
> imbalance (more photons on the outside rather than
> in-between the plates), and this imbalance increases as
> more and more sizes of photons are excluded from between
> the ever-closer plates. EITHER Real or Virtual.
The external area of the plates is constant. Calculate the varying
numerical aperture of the varying gap and answer your own question.
Compare the perimeter/area ratios for circles, squares and
rectangles. Why is the Casimir effect not dependent upon a shape
factor (compactness, re laser ring gyros)?
> Now personally I think that the quantity of Real photons
> pressing on the plates is far too insufficient to
> explain the observed force (I favor the standard
> explanation). But to "win" the discussion previously
> mentioned, I'd like to be sure that NO Real photons
> can be involved in a Casimir Test. Thus my question
> about it ever having been performed inside a solid
> metal Faraday Cage. So, HAS it been done? Thanks!
The point of good physics is that the results of calculation are
indistinguishable from experimental results. Since your proposal
creates contradictions with both observed fact and calculation -
qualitative and quantitative - it is wrong.
How would you construct a "Faraday cage" to meet your specs? The
etalon gaps used to make measurements are typically a few thousand nm
(IR) to optical gaps. Do the run in ambient light vs. darkness or
with varying temp - some of them must deviate. Your argument is not
weak, it is empirically dead. (Did you ever consider that the
measurement region is within shielding to exclude EM, magnetic, and
other extraneous inteferences?)
http://www.mazepath.com/uncleal/casimir3.htm
Bottom line: The Casimir effect at very small gaps cannot be
distinguishable from ordinary lattice forces or anomalous /_\H of
formations would be seen assembling or disassembling a lattice (e.g.
graphite, boron nitride, heavy metal chalcogenides, smectite clays,
zirconium phosphate and phosphonates, micas, or any other lamellar
solids as extreme cases). The Casimir effect obeys standard physics.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
vernonner3voltazim
Oct27-04, 10:56 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\n\nUncle Al <UncleAl0@hate.spam.net> wrote:\n> vernonner3voltazim wrote:\n> >\n> > We are describing an effect of light pressure\n> > on BOTH sides of BOTH plates. When there is room for the\n> > photons to fit between the plates, the light pressure is\n> > balanced and there is no force. When there is little\n> > room, we can compute a force that results from the\n> > imbalance (more photons on the outside rather than\n> > in-between the plates), and this imbalance increases as\n> > more and more sizes of photons are excluded from between\n> > the ever-closer plates. EITHER Real or Virtual.\n>\n> The external area of the plates is constant. Calculate\n> the varying numerical aperture of the varying gap and\n> answer your own question. Compare the perimeter/area\n> ratios for circles, squares and rectangles. Why is the\n> Casimir effect not dependent upon a shape factor\n> (compactness, re laser ring gyros)?\n> >\nIf you are talking about pairs of plates having various\nmatched shapes, and all the plates still have the same\nsurface area, then I see no problem. When one describes\nsome tiny quantity of dynes per square meter, that\nquantity is independent of the number of square meters,\nor how they are shaped. If you are talking about\nsomething else, then please clarify. (Thanks!)\n> >\n> > Thus my question\n> > about it ever having been performed inside a solid\n> > metal Faraday Cage. So, HAS it been done?\n>\n> The point of good physics is that the results of\n> calculation are indistinguishable from experimental\n> results. Since your proposal creates contradictions\n> with both observed fact and calculation -\n> qualitative and quantitative - it is wrong.\n> >\nUmmm, which proposal? The other fellow wants to\ntie the Casimir effect to ordinary Real photons.\nI\'m confident that that cannot work. Yet from\nthe link you provided below, it appears you\ndisagree with the Standard proposal, also....\n> >\n> How would you construct a "Faraday cage" to meet\n> your specs?\n> >\nAccording to others\' posts in this Thread, it\nwould have to be chilled close to Absolute Zero.\nWhich is not a problem if the Test is expected\nto be performed in a vacuum, and the two plates\nare equally cold. I can agree that it may be\nunlikely to exclude ALL thermal-related Real\nphotons. But their numbers CAN be diminished\nto the point that we can be confident their\npresence is insignificant. (Meanwhile, outside\nthe Faraday box, lots of shielding is used to\nprevent permeation by any stray high-energy\nphotons.)\n> >\n> The etalon gaps used to make\n> measurements are typically a few thousand nm\n> (IR) to optical gaps. Do the run in ambient\n> light vs. darkness or with varying temp - some\n> of them must deviate. Your argument is not\n> weak, it is empirically dead.\n> >\nAgain, I am not the one who thinks that ordinary\nphotons can explain the known magnitude of the\nCasimir Effect. Yet if virtual particles in\nthe vacuum did not exist, then some semblence\nof that Effect might be detectable and\nproperly blamed on ambient Real photons.\n> >\n> (Did you ever\n> consider that the measurement region is within\n> shielding to exclude EM, magnetic, and\n> other extraneous inteferences?)\n> >\nActually, I suspected it, but wanted to be sure.\n> >\n> http://www.mazepath.com/uncleal/casimir3.htm\n> >\nAn interesting discussion!\n> >\n> Bottom line: The Casimir effect at very small\n> gaps cannot be distinguishable from ordinary\n> lattice forces or anomalous /_\\H of formations\n> would be seen assembling or disassembling a\n> lattice (e.g. graphite, boron nitride, heavy\n> metal chalcogenides, smectite clays, zirconium\n> phosphate and phosphonates, micas, or any other\n> lamellar solids as extreme cases). The Casimir\n> effect obeys standard physics.\n> >\nActually, I think you might have missed something.\nPROVIDED that the tests you are describing have\nnot actually been performed (hard to tell on that\nlinked page). It seems to me that if the Casimir\neffect can be equalled as you suggest, then *IF*\nit is actually a Real Phenomenon Of The Vacuum,\nthen anyone conducting your suggested Test would\ndetect a compounded Force, due to BOTH the virtuals\nin the vacuum AND the van der Waals (or equivalent)\nforces.\n\nOn the other hand, I get the idea that you are\ndescribing the construction of thin mirrors from\nnon-metallic/non-conductive materials. Normally\nthe Casimir Effect doesn\'t work with nonconductors.\nIf that was some kind of oddball Absolute, then\nin the above Test the virtuals would ignore these\nspecial mirrors, and only the ordinary intermolecular\nforces would be detected. I\'m not sure which way\nto bet, here. HAS that Test been done?\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:
> vernonner3voltazim wrote:
> >
> > We are describing an effect of light pressure
> > on BOTH sides of BOTH plates. When there is room for the
> > photons to fit between the plates, the light pressure is
> > balanced and there is no force. When there is little
> > room, we can compute a force that results from the
> > imbalance (more photons on the outside rather than
> > in-between the plates), and this imbalance increases as
> > more and more sizes of photons are excluded from between
> > the ever-closer plates. EITHER Real or Virtual.
>
> The external area of the plates is constant. Calculate
> the varying numerical aperture of the varying gap and
> answer your own question. Compare the perimeter/area
> ratios for circles, squares and rectangles. Why is the
> Casimir effect not dependent upon a shape factor
> (compactness, re laser ring gyros)?
> >
If you are talking about pairs of plates having various
matched shapes, and all the plates still have the same
surface area, then I see no problem. When one describes
some tiny quantity of dynes per square meter, that
quantity is independent of the number of square meters,
or how they are shaped. If you are talking about
something else, then please clarify. (Thanks!)
> >
> > Thus my question
> > about it ever having been performed inside a solid
> > metal Faraday Cage. So, HAS it been done?
>
> The point of good physics is that the results of
> calculation are indistinguishable from experimental
> results. Since your proposal creates contradictions
> with both observed fact and calculation -
> qualitative and quantitative - it is wrong.
> >
Ummm, which proposal? The other fellow wants to
tie the Casimir effect to ordinary Real photons.
I'm confident that that cannot work. Yet from
the link you provided below, it appears you
disagree with the Standard proposal, also....
> >
> How would you construct a "Faraday cage" to meet
> your specs?
> >
According to others' posts in this Thread, it
would have to be chilled close to Absolute Zero.
Which is not a problem if the Test is expected
to be performed in a vacuum, and the two plates
are equally cold. I can agree that it may be
unlikely to exclude ALL thermal-related Real
photons. But their numbers CAN be diminished
to the point that we can be confident their
presence is insignificant. (Meanwhile, outside
the Faraday box, lots of shielding is used to
prevent permeation by any stray high-energy
photons.)
> >
> The etalon gaps used to make
> measurements are typically a few thousand nm
> (IR) to optical gaps. Do the run in ambient
> light vs. darkness or with varying temp - some
> of them must deviate. Your argument is not
> weak, it is empirically dead.
> >
Again, I am not the one who thinks that ordinary
photons can explain the known magnitude of the
Casimir Effect. Yet if virtual particles in
the vacuum did not exist, then some semblence
of that Effect might be detectable and
properly blamed on ambient Real photons.
> >
> (Did you ever
> consider that the measurement region is within
> shielding to exclude EM, magnetic, and
> other extraneous inteferences?)
> >
Actually, I suspected it, but wanted to be sure.
> >
> http://www.mazepath.com/uncleal/casimir3.htm
> >
An interesting discussion!
> >
> Bottom line: The Casimir effect at very small
> gaps cannot be distinguishable from ordinary
> lattice forces or anomalous /_\H of formations
> would be seen assembling or disassembling a
> lattice (e.g. graphite, boron nitride, heavy
> metal chalcogenides, smectite clays, zirconium
> phosphate and phosphonates, micas, or any other
> lamellar solids as extreme cases). The Casimir
> effect obeys standard physics.
> >
Actually, I think you might have missed something.
PROVIDED that the tests you are describing have
not actually been performed (hard to tell on that
linked page). It seems to me that if the Casimir
effect can be equalled as you suggest, then *IF*
it is actually a Real Phenomenon Of The Vacuum,
then anyone conducting your suggested Test would
detect a compounded Force, due to BOTH the virtuals
in the vacuum AND the van der Waals (or equivalent)
forces.
On the other hand, I get the idea that you are
describing the construction of thin mirrors from
non-metallic/non-conductive materials. Normally
the Casimir Effect doesn't work with nonconductors.
If that was some kind of oddball Absolute, then
in the above Test the virtuals would ignore these
special mirrors, and only the ordinary intermolecular
forces would be detected. I'm not sure which way
to bet, here. HAS that Test been done?
Uncle Al
Oct28-04, 01:29 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\nvernonner3voltazim wrote:\n>\n> Uncle Al <UncleAl0@hate.spam.net> wrote:\n> > vernonner3voltazim wrote:\n[snip]\n\n> > How would you construct a "Faraday cage" to meet\n> > your specs?\n> > >\n> According to others\' posts in this Thread, it\n> would have to be chilled close to Absolute Zero.\n> Which is not a problem if the Test is expected\n> to be performed in a vacuum, and the two plates\n> are equally cold. I can agree that it may be\n> unlikely to exclude ALL thermal-related Real\n> photons. But their numbers CAN be diminished\n> to the point that we can be confident their\n> presence is insignificant. (Meanwhile, outside\n> the Faraday box, lots of shielding is used to\n> prevent permeation by any stray high-energy\n> photons.)\n\nGet thee to a library,\n\nH.B.G. Casimir, Proc. Kon. Ned. Akad. Wetensch. B51 793 (1948)\nPhys. Rev. B. 30(4) 1700 (1984), JETP 2 73 (1956)\nContemporary Physics 33(5) 313 (1992)\nSov. Phys.-Dokl. 12(11) 1040 (1968)\nProc. Royal Soc. A 312 435 (1969)\nAnn. Phys. (NY) 56 474 (1970)\nPhys. Rev. E 48(2) 1562 (1993)\nEdward G. Harris, A Pedestrian Approach to Quantum Field Theory.\nWiley-Interscience, NY 1972, pp. 108-9\n\nMeasured to within 5% of theory, Phys. Rev. Lett. 78 5 (1996)\nPhys. Rev. Lett. 81 4549 (1998)\nMeasured to within 1% of theory, Phys. Rev. A 59(5) R3149 (1999)\nImperfect mirrors, Phys. Rev. Lett. 81 3815 (1998)\nTemperature above 0 K, Phys. Rev. A 57 1870 (1998)\nCurved mirrors, Amer. J. Physics 65 381 (1997))\nSpherical dielectrics, J. Phys. A: Math. Gen. 32 535 (1999)\n\n[snip]\n\n1) When you find yourself at the bottom of a deep hole, stop\ndigging.\n2) When you find yourself riding a dead horse, dismount. The\nalternatives are unacceptable,\n\nhttp://www.mazepath.com/uncleal/horse.htm\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>vernonner3voltazim wrote:
>
> Uncle Al <UncleAl0@hate.spam.net> wrote:
> > vernonner3voltazim wrote:
[snip]
> > How would you construct a "Faraday cage" to meet
> > your specs?
> > >
> According to others' posts in this Thread, it
> would have to be chilled close to Absolute Zero.
> Which is not a problem if the Test is expected
> to be performed in a vacuum, and the two plates
> are equally cold. I can agree that it may be
> unlikely to exclude ALL thermal-related Real
> photons. But their numbers CAN be diminished
> to the point that we can be confident their
> presence is insignificant. (Meanwhile, outside
> the Faraday box, lots of shielding is used to
> prevent permeation by any stray high-energy
> photons.)
Get thee to a library,
H.B.G. Casimir, Proc. Kon. Ned. Akad. Wetensch. B51 793 (1948)
Phys. Rev. B. 30(4) 1700 (1984), JETP 2 73 (1956)
Contemporary Physics 33(5) 313 (1992)
Sov. Phys.-Dokl. 12(11) 1040 (1968)
Proc. Royal Soc. A 312 435 (1969)
Ann. Phys. (NY) 56 474 (1970)
Phys. Rev. E 48(2) 1562 (1993)
Edward G. Harris, A Pedestrian Approach to Quantum Field Theory.
Wiley-Interscience, NY 1972, pp. 108-9
Measured to within 5% of theory, Phys. Rev. Lett. 78 5 (1996)
Phys. Rev. Lett. 81 4549 (1998)
Measured to within 1% of theory, Phys. Rev. A 59(5) R3149 (1999)
Imperfect mirrors, Phys. Rev. Lett. 81 3815 (1998)
Temperature above K, Phys. Rev. A 57 1870 (1998)
Curved mirrors, Amer. J. Physics 65 381 (1997))
Spherical dielectrics, J. Phys. A: Math. Gen. 32 535 (1999)
[snip]
1) When you find yourself at the bottom of a deep hole, stop
digging.
2) When you find yourself riding a dead horse, dismount. The
alternatives are unacceptable,
http://www.mazepath.com/uncleal/horse.htm
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
zigoteau
Nov4-04, 03:42 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>vnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0410252111.7a17e86f@posting.google. com>...\n\nHi, Vernon,\n\n> Ummm, which proposal? The other fellow wants to\n> tie the Casimir effect to ordinary Real photons.\n> I\'m confident that that cannot work.\n\nAnd you are right! As Uncle Al says, real photons will give a force\nwhich is essentially independent of the spacing between the plates.\n\n> Again, I am not the one who thinks that ordinary\n> photons can explain the known magnitude of the\n> Casimir Effect. Yet if virtual particles in\n> the vacuum did not exist,\n\nThe point of virtual particles is that they are virtual. Their\nexistence is at best tenuous.\n\n> Actually, I think you might have missed something.\n> PROVIDED that the tests you are describing have\n> not actually been performed (hard to tell on that\n> linked page). It seems to me that if the Casimir\n> effect can be equalled as you suggest, then *IF*\n> it is actually a Real Phenomenon Of The Vacuum,\n> then anyone conducting your suggested Test would\n> detect a compounded Force, due to BOTH the virtuals\n> in the vacuum AND the van der Waals (or equivalent)\n> forces.\n\nI suggest that a good step for you would be to read the original\nCasimir (and Polder) papers. Their content might surprise you.\n\nFirstly, Casimir carried out his calculations to try to explain\nmeasurements on colloids. The Casimir interaction *is* the van der\nWaals interaction, usually at separations greater than the wavelength\nof photons of energy comparable to the binding energy of electrons in\nthe materials you are investigating. Since this is typically in the\nrange 10-100 eV, the transition from the r^-6 point-to-point behavior\nof the London analysis to the r^-7 behavior of the Casimir analysis\noccurs between 10-100 nm.\n\n> On the other hand, I get the idea that you are\n> describing the construction of thin mirrors from\n> non-metallic/non-conductive materials. Normally\n> the Casimir Effect doesn\'t work with nonconductors.\n\nWhere did you get that idea from? This may just involve the meanings\nyou are attaching to words, but Casimir\'s calculations work equally\nwell for dielectrics as for metals. The form of the result just\nbecomes particularly simple, and independent of the particular\nmaterial involved, for metals separated by large distances.\n\n> If that was some kind of oddball Absolute, then\n> in the above Test the virtuals would ignore these\n> special mirrors, and only the ordinary intermolecular\n> forces would be detected.\n\nBut the Casimir forces *are* just the ordinary intermolecular forces,\npossibly in the asymptotic regime of large separations.\n\nCheers,\n\nZigoteau.\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>vnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0410252111.7a17e86f@posting.google.com>...
Hi, Vernon,
> Ummm, which proposal? The other fellow wants to
> tie the Casimir effect to ordinary Real photons.
> I'm confident that that cannot work.
And you are right! As Uncle Al says, real photons will give a force
which is essentially independent of the spacing between the plates.
> Again, I am not the one who thinks that ordinary
> photons can explain the known magnitude of the
> Casimir Effect. Yet if virtual particles in
> the vacuum did not exist,
The point of virtual particles is that they are virtual. Their
existence is at best tenuous.
> Actually, I think you might have missed something.
> PROVIDED that the tests you are describing have
> not actually been performed (hard to tell on that
> linked page). It seems to me that if the Casimir
> effect can be equalled as you suggest, then *IF*
> it is actually a Real Phenomenon Of The Vacuum,
> then anyone conducting your suggested Test would
> detect a compounded Force, due to BOTH the virtuals
> in the vacuum AND the van der Waals (or equivalent)
> forces.
I suggest that a good step for you would be to read the original
Casimir (and Polder) papers. Their content might surprise you.
Firstly, Casimir carried out his calculations to try to explain
measurements on colloids. The Casimir interaction *is* the van der
Waals interaction, usually at separations greater than the wavelength
of photons of energy comparable to the binding energy of electrons in
the materials you are investigating. Since this is typically in the
range 10-100 eV, the transition from the r^-6 point-to-point behavior
of the London analysis to the r^-7 behavior of the Casimir analysis
occurs between 10-100 nm.
> On the other hand, I get the idea that you are
> describing the construction of thin mirrors from
> non-metallic/non-conductive materials. Normally
> the Casimir Effect doesn't work with nonconductors.
Where did you get that idea from? This may just involve the meanings
you are attaching to words, but Casimir's calculations work equally
well for dielectrics as for metals. The form of the result just
becomes particularly simple, and independent of the particular
material involved, for metals separated by large distances.
> If that was some kind of oddball Absolute, then
> in the above Test the virtuals would ignore these
> special mirrors, and only the ordinary intermolecular
> forces would be detected.
But the Casimir forces *are* just the ordinary intermolecular forces,
possibly in the asymptotic regime of large separations.
Cheers,
Zigoteau.
vernonner3voltazim
Nov5-04, 08:21 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>\nzigoteau@yahoo.com (zigoteau) wrote:\n>\n> I suggest that a good step for you would be to read\n> the original Casimir (and Polder) papers. Their\n> content might surprise you.\n>\n> Firstly, Casimir carried out his calculations to try\n> to explain measurements on colloids. The Casimir\n> interaction *is* the van der Waals interaction,\n> usually at separations greater than the wavelength\n> of photons of energy comparable to the binding\n> energy of electrons in the materials you are\n> investigating. Since this is typically in the\n> range 10-100 eV, the transition from the r^-6\n> point-to-point behavior of the London analysis to\n> the r^-7 behavior of the Casimir analysis occurs\n> between 10-100 nm.\n>\nHMMMMMM!\nAnd here all these years went by with me thinking (as I\nonce read somewhere) that van der Waals forces were\ncaused by the electrons of one atom temporarily\n"seeing" the protons of another atom. Take two argon\natoms, for example. Each has 18 protons with 18\nelectrons "orbitally" clouding around it. If by sheer\nrandomness something like this happens:\n\n(8e) (18p) (10e) (8e) (18p) (10e)\n\nWell, the nucleus of the argon at the right can be\n"seen" by 2 of those 10 electrons of the argon at\nthe left. So the atoms attract.\n\nNow of course I realize that such arrangements are\nfleeting and will no doubt be balanced by other\narrangements that are electrically repulsive. I\nhave in fact wondered about that, whether or not\nthe overall average tends toward zero attraction.\n(Not to mention that Helium manages near-zero\nattraction with only 2 electrons shrouding the\nnucleus, even at Absolute Zero.) Yet van der\nWaals forces do exist, and so I accepted the\nexplanation that I had read about.\n\nThanks for the enlightenment. HMMMMMM....\n\nRegarding the nonconductor/mirrors, that was\njust something I thought Uncle Al might be\ndescribing at a page he had linked to. I\ncould be mistaken about that, of course.\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>zigoteau@yahoo.com (zigoteau) wrote:
>
> I suggest that a good step for you would be to read
> the original Casimir (and Polder) papers. Their
> content might surprise you.
>
> Firstly, Casimir carried out his calculations to try
> to explain measurements on colloids. The Casimir
> interaction *is* the van der Waals interaction,
> usually at separations greater than the wavelength
> of photons of energy comparable to the binding
> energy of electrons in the materials you are
> investigating. Since this is typically in the
> range 10-100 eV, the transition from the r^-6
> point-to-point behavior of the London analysis to
> the r^-7 behavior of the Casimir analysis occurs
> between 10-100 nm.
>
HMMMMMM!
And here all these years went by with me thinking (as I
once read somewhere) that van der Waals forces were
caused by the electrons of one atom temporarily
"seeing" the protons of another atom. Take two argon
atoms, for example. Each has 18 protons with 18
electrons "orbitally" clouding around it. If by sheer
randomness something like this happens:
(8e) (18p) (10e) (8e) (18p) (10e)
Well, the nucleus of the argon at the right can be
"seen" by 2 of those 10 electrons of the argon at
the left. So the atoms attract.
Now of course I realize that such arrangements are
fleeting and will no doubt be balanced by other
arrangements that are electrically repulsive. I
have in fact wondered about that, whether or not
the overall average tends toward zero attraction.
(Not to mention that Helium manages near-zero
attraction with only 2 electrons shrouding the
nucleus, even at Absolute Zero.) Yet van der
Waals forces do exist, and so I accepted the
explanation that I had read about.
Thanks for the enlightenment. HMMMMMM....
Regarding the nonconductor/mirrors, that was
just something I thought Uncle Al might be
describing at a page he had linked to. I
could be mistaken about that, of course.
Uncle Al
Nov7-04, 07:44 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\nvernonner3voltazim wrote:\n>\n> zigoteau@yahoo.com (zigoteau) wrote:\n> >\n> > I suggest that a good step for you would be to read\n> > the original Casimir (and Polder) papers. Their\n> > content might surprise you.\n> >\n> > Firstly, Casimir carried out his calculations to try\n> > to explain measurements on colloids. The Casimir\n> > interaction *is* the van der Waals interaction,\n> > usually at separations greater than the wavelength\n> > of photons of energy comparable to the binding\n> > energy of electrons in the materials you are\n> > investigating. Since this is typically in the\n> > range 10-100 eV, the transition from the r^-6\n> > point-to-point behavior of the London analysis to\n> > the r^-7 behavior of the Casimir analysis occurs\n> > between 10-100 nm.\n> >\n> HMMMMMM!\n> And here all these years went by with me thinking (as I\n> once read somewhere) that van der Waals forces were\n> caused by the electrons of one atom temporarily\n> "seeing" the protons of another atom. Take two argon\n> atoms, for example. Each has 18 protons with 18\n> electrons "orbitally" clouding around it. If by sheer\n> randomness something like this happens:\n>\n> (8e) (18p) (10e) (8e) (18p) (10e)\n>\n> Well, the nucleus of the argon at the right can be\n> "seen" by 2 of those 10 electrons of the argon at\n> the left. So the atoms attract.\n>\n> Now of course I realize that such arrangements are\n> fleeting and will no doubt be balanced by other\n> arrangements that are electrically repulsive. I\n> have in fact wondered about that, whether or not\n> the overall average tends toward zero attraction.\n> (Not to mention that Helium manages near-zero\n> attraction with only 2 electrons shrouding the\n> nucleus, even at Absolute Zero.) Yet van der\n> Waals forces do exist, and so I accepted the\n> explanation that I had read about.\n>\n> Thanks for the enlightenment. HMMMMMM....\n>\n> Regarding the nonconductor/mirrors, that was\n> just something I thought Uncle Al might be\n> describing at a page he had linked to. I\n> could be mistaken about that, of course.\n\nhttp://www.mazepath.com/uncleal/casimir3.htm\nA chemist diddling with applied physics\n\nNewer stuff:\n\nhttp://arXiv.org/abs/hep-th/0104127\nFor a hollow spherical shell of radius R, Casimir force\nPhys. Rev. E 63 1101-1112 (2001)\nRefutation of repulsive Casimir force\n\nMeasured to within 5% of theory, Phys. Rev. Lett. 78 5 (1996)\nPhys. Rev. Lett. 81 4549 (1998)\nMeasured to within 1% of theory, Phys. Rev. A 59(5) R3149 (1999)\nImperfect mirrors, Phys. Rev. Lett. 81 3815 (1998)\nTemperature above 0 K, Phys. Rev. A 57 1870 (1998)\nCurved mirrors, Amer. J. Physics 65 381 (1997))\nSpherical dielectrics, J. Phys. A: Math. Gen. 32 535 (1999)\n\nH.B.G. Casimir, Proc. Kon. Ned. Akad. Wetensch. B51 793 (1948)\nContemporary Physics 33(5) 313 (1992)\nSov. Phys.-Dokl. 12(11) 1040 (1968)\nProc. Royal Soc. A 312 435 (1969)\nAnn. Phys. (NY) 56 474 (1970)\nPhys. Rev. E 48(2) 1562 (1993)\nEdward G. Harris, A Pedestrian Approach to Quantum Field Theory.\nWiley-Interscience, NY 1972, pp. 108-9\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>vernonner3voltazim wrote:
>
> zigoteau@yahoo.com (zigoteau) wrote:
> >
> > I suggest that a good step for you would be to read
> > the original Casimir (and Polder) papers. Their
> > content might surprise you.
> >
> > Firstly, Casimir carried out his calculations to try
> > to explain measurements on colloids. The Casimir
> > interaction *is* the van der Waals interaction,
> > usually at separations greater than the wavelength
> > of photons of energy comparable to the binding
> > energy of electrons in the materials you are
> > investigating. Since this is typically in the
> > range 10-100 eV, the transition from the r^-6
> > point-to-point behavior of the London analysis to
> > the r^-7 behavior of the Casimir analysis occurs
> > between 10-100 nm.
> >
> HMMMMMM!
> And here all these years went by with me thinking (as I
> once read somewhere) that van der Waals forces were
> caused by the electrons of one atom temporarily
> "seeing" the protons of another atom. Take two argon
> atoms, for example. Each has 18 protons with 18
> electrons "orbitally" clouding around it. If by sheer
> randomness something like this happens:
>
> (8e) (18p) (10e) (8e) (18p) (10e)
>
> Well, the nucleus of the argon at the right can be
> "seen" by 2 of those 10 electrons of the argon at
> the left. So the atoms attract.
>
> Now of course I realize that such arrangements are
> fleeting and will no doubt be balanced by other
> arrangements that are electrically repulsive. I
> have in fact wondered about that, whether or not
> the overall average tends toward zero attraction.
> (Not to mention that Helium manages near-zero
> attraction with only 2 electrons shrouding the
> nucleus, even at Absolute Zero.) Yet van der
> Waals forces do exist, and so I accepted the
> explanation that I had read about.
>
> Thanks for the enlightenment. HMMMMMM....
>
> Regarding the nonconductor/mirrors, that was
> just something I thought Uncle Al might be
> describing at a page he had linked to. I
> could be mistaken about that, of course.
http://www.mazepath.com/uncleal/casimir3.htm
A chemist diddling with applied physics
Newer stuff:
http://arXiv.org/abs/http://www.arxiv.org/abs/hep-th/0104127
For a hollow spherical shell of radius R, Casimir force
Phys. Rev. E 63 1101-1112 (2001)
Refutation of repulsive Casimir force
Measured to within 5% of theory, Phys. Rev. Lett. 78 5 (1996)
Phys. Rev. Lett. 81 4549 (1998)
Measured to within 1% of theory, Phys. Rev. A 59(5) R3149 (1999)
Imperfect mirrors, Phys. Rev. Lett. 81 3815 (1998)
Temperature above K, Phys. Rev. A 57 1870 (1998)
Curved mirrors, Amer. J. Physics 65 381 (1997))
Spherical dielectrics, J. Phys. A: Math. Gen. 32 535 (1999)
H.B.G. Casimir, Proc. Kon. Ned. Akad. Wetensch. B51 793 (1948)
Contemporary Physics 33(5) 313 (1992)
Sov. Phys.-Dokl. 12(11) 1040 (1968)
Proc. Royal Soc. A 312 435 (1969)
Ann. Phys. (NY) 56 474 (1970)
Phys. Rev. E 48(2) 1562 (1993)
Edward G. Harris, A Pedestrian Approach to Quantum Field Theory.
Wiley-Interscience, NY 1972, pp. 108-9
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
zigoteau
Nov7-04, 07:44 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\nvnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0411042101.4c916cef@posting.google. com>...\n\nHi, Vernon,\n\n\n> > Firstly, Casimir carried out his calculations to try\n> > to explain measurements on colloids. The Casimir\n> > interaction *is* the van der Waals interaction,\n> > usually at separations greater than the wavelength\n> > of photons of energy comparable to the binding\n> > energy of electrons in the materials you are\n> > investigating. Since this is typically in the\n> > range 10-100 eV, the transition from the r^-6\n> > point-to-point behavior of the London analysis to\n> > the r^-7 behavior of the Casimir analysis occurs\n> > between 10-100 nm.\n> >\n> HMMMMMM!\n> And here all these years went by with me thinking (as I\n> once read somewhere) that van der Waals forces were\n> caused by the electrons of one atom temporarily\n> "seeing" the protons of another atom. Take two argon\n> atoms, for example. Each has 18 protons with 18\n> electrons "orbitally" clouding around it. If by sheer\n> randomness something like this happens:\n>\n> (8e) (18p) (10e) (8e) (18p) (10e)\n>\n> Well, the nucleus of the argon at the right can be\n> "seen" by 2 of those 10 electrons of the argon at\n> the left. So the atoms attract.\n\nWell, that description is not wrong. One thing you have to get used to\nin physics is that a given phenomenon can often be described in a\nnumber of ways, apparently quite different from one another.\n\nWhat you are describing there springs from the theoretical treatment\nof the vdW interaction by Fritz London [Trans. Faraday Soc. 33, 8-26\n(1937)]. London\'s treatment of the interaction was the first one which\nfitted the experimental facts known at the time, and it described the\nelectrons using the Schrödinger equation. The electrons were assumed\nto interact with the nuclei and with one another via a 1/r potential\nwhich acted instantaneously.\n\nFor teaching purposes it is necessary to describe the origin of the\nenergy in words. This is said to be the interaction between\nfluctuations of the electrons. However remember, the wave function of\nthe electrons does not fluctuate and the atoms as a whole have zero\nexpectation value of their external electric field.\n\nThat was all fine and dandy for a while, and explained lots of things.\nOn its foundations was built the DLVO theory of the stability of\ncolloids (D=Derjaguin, L=Landau, V=Verwey and O=Overbeek). However,\nafter a while slight discrepancies with the theory were noted, and\nthis was where Casimir and his student Polder came in. They provided a\ncorrect quantum description of both the electrons and photons [H B G\nCasimir, D Polder Phys. Rev. 73 (1948) 360], and resolved the\ndiscrepancies of the DLVO theory. Almost as an afterthought, Casimir\nnoted that if you had parallel metal plates separated by large\ndistances, the interaction was independent of which particular metal\nyou used [H B G Casimir Proc. Kon. Ned. Akad. Wetensch. B 51 (1948)\n793] and could be considered to originate from the energy of\nzero-point fluctuations of the electromagnetic field.\n\nThis of course was a green light for the mystics, who often\nconveniently forget that to get any force at all you do have to have\nsome matter there (the metal plates), and that when you bring the\nplates together to get a larger force, it does start to matter which\nmetal you use.\n\nJust in case you think the Casimir treatment disproves the\n\'electron-fluctuation\' description, Lifshitz showed that London\'s\ntreatment could be fixed up by putting in a retardation term in the\nformula. The improved Lifshitz electron-fluctuation treatment gives\nexactly the same answer as the Casimir zero-point-photon-fluctuation\npicture.\n\nThere is a third picture of the vdW interaction, which as far as I\nknow was first put forward by Hirschfelder and Eliason [J. Chem. Phys.\n47 (1967) 1164-1169]. When the atoms approach one another, the\norbitals of the electrons change slightly, and this changes the\ndistribution of negative charge around each nucleus, distorting the\ncloud slightly in the direction of the other nucleus. The nucleus\ntherefore feels a force with a value exactly equal to the result given\nby the Lifshitz-London analysis, which is exactly equal to the value\ngiven by the Casimir-Polder analysis. There is however a subtle\ndifference. The third picture says that the energy of the interaction\ncomes from the attraction between opposite charges. This is a lot less\nmysterious, and the people attracted to physics by the Copenhagen\ninterpretation don\'t like it.\n\n\n> Now of course I realize that such arrangements are\n> fleeting and will no doubt be balanced by other\n> arrangements that are electrically repulsive. I\n> have in fact wondered about that, whether or not\n> the overall average tends toward zero attraction.\n> (Not to mention that Helium manages near-zero\n> attraction with only 2 electrons shrouding the\n> nucleus, even at Absolute Zero.) Yet van der\n> Waals forces do exist, and so I accepted the\n> explanation that I had read about.\n>\n> Thanks for the enlightenment. HMMMMMM....\n>\n> Regarding the nonconductor/mirrors, that was\n> just something I thought Uncle Al might be\n> describing at a page he had linked to. I\n> could be mistaken about that, of course.\n\nCheers,\n\nZigoteau.\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>vnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0411042101.4c916cef@posting.google.com>...
Hi, Vernon,
> > Firstly, Casimir carried out his calculations to try
> > to explain measurements on colloids. The Casimir
> > interaction *is* the van der Waals interaction,
> > usually at separations greater than the wavelength
> > of photons of energy comparable to the binding
> > energy of electrons in the materials you are
> > investigating. Since this is typically in the
> > range 10-100 eV, the transition from the r^-6
> > point-to-point behavior of the London analysis to
> > the r^-7 behavior of the Casimir analysis occurs
> > between 10-100 nm.
> >
> HMMMMMM!
> And here all these years went by with me thinking (as I
> once read somewhere) that van der Waals forces were
> caused by the electrons of one atom temporarily
> "seeing" the protons of another atom. Take two argon
> atoms, for example. Each has 18 protons with 18
> electrons "orbitally" clouding around it. If by sheer
> randomness something like this happens:
>
> (8e) (18p) (10e) (8e) (18p) (10e)
>
> Well, the nucleus of the argon at the right can be
> "seen" by 2 of those 10 electrons of the argon at
> the left. So the atoms attract.
Well, that description is not wrong. One thing you have to get used to
in physics is that a given phenomenon can often be described in a
number of ways, apparently quite different from one another.
What you are describing there springs from the theoretical treatment
of the vdW interaction by Fritz London [Trans. Faraday Soc. 33, 8-26
(1937)]. London's treatment of the interaction was the first one which
fitted the experimental facts known at the time, and it described the
electrons using the Schrödinger equation. The electrons were assumed
to interact with the nuclei and with one another via a 1/r potential
which acted instantaneously.
For teaching purposes it is necessary to describe the origin of the
energy in words. This is said to be the interaction between
fluctuations of the electrons. However remember, the wave function of
the electrons does not fluctuate and the atoms as a whole have zero
expectation value of their external electric field.
That was all fine and dandy for a while, and explained lots of things.
On its foundations was built the DLVO theory of the stability of
colloids (D=Derjaguin, L=Landau, V=Verwey and O=Overbeek). However,
after a while slight discrepancies with the theory were noted, and
this was where Casimir and his student Polder came in. They provided a
correct quantum description of both the electrons and photons [H B G
Casimir, D Polder Phys. Rev. 73 (1948) 360], and resolved the
discrepancies of the DLVO theory. Almost as an afterthought, Casimir
noted that if you had parallel metal plates separated by large
distances, the interaction was independent of which particular metal
you used [H B G Casimir Proc. Kon. Ned. Akad. Wetensch. B 51 (1948)
793] and could be considered to originate from the energy of
zero-point fluctuations of the electromagnetic field.
This of course was a green light for the mystics, who often
conveniently forget that to get any force at all you do have to have
some matter there (the metal plates), and that when you bring the
plates together to get a larger force, it does start to matter which
metal you use.
Just in case you think the Casimir treatment disproves the
'electron-fluctuation' description, Lifshitz showed that London's
treatment could be fixed up by putting in a retardation term in the
formula. The improved Lifshitz electron-fluctuation treatment gives
exactly the same answer as the Casimir zero-point-photon-fluctuation
picture.
There is a third picture of the vdW interaction, which as far as I
know was first put forward by Hirschfelder and Eliason [J. Chem. Phys.
47 (1967) 1164-1169]. When the atoms approach one another, the
orbitals of the electrons change slightly, and this changes the
distribution of negative charge around each nucleus, distorting the
cloud slightly in the direction of the other nucleus. The nucleus
therefore feels a force with a value exactly equal to the result given
by the Lifshitz-London analysis, which is exactly equal to the value
given by the Casimir-Polder analysis. There is however a subtle
difference. The third picture says that the energy of the interaction
comes from the attraction between opposite charges. This is a lot less
mysterious, and the people attracted to physics by the Copenhagen
interpretation don't like it.
> Now of course I realize that such arrangements are
> fleeting and will no doubt be balanced by other
> arrangements that are electrically repulsive. I
> have in fact wondered about that, whether or not
> the overall average tends toward zero attraction.
> (Not to mention that Helium manages near-zero
> attraction with only 2 electrons shrouding the
> nucleus, even at Absolute Zero.) Yet van der
> Waals forces do exist, and so I accepted the
> explanation that I had read about.
>
> Thanks for the enlightenment. HMMMMMM....
>
> Regarding the nonconductor/mirrors, that was
> just something I thought Uncle Al might be
> describing at a page he had linked to. I
> could be mistaken about that, of course.
Cheers,
Zigoteau.
vernonner3voltazim
Nov8-04, 05:11 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>> zigoteau@yahoo.com (zigoteau) wrote:\n> > vnemitz@pinn.net (vernonner3voltazim) wrote:\n> > > zigoteau@yahoo.com (zigoteau) wrote:\n> > >\n> > > Firstly, Casimir carried out his calculations to try\n> > > to explain measurements on colloids. The Casimir\n> > > interaction *is* the van der Waals interaction,\n<snip>\n> > >\n> > And here all these years went by with me thinking (as I\n> > once read somewhere) that van der Waals forces were\n> > caused by the electrons of one atom temporarily\n> > "seeing" the protons of another atom.\n<snip>\n> >\n> Well, that description is not wrong. One thing you have\n> to get used to in physics is that a given phenomenon\n> can often be described in a number of ways, apparently\n> quite different from one another.\n> >\nOh, I don\'t have a problem with that. My problem\nis finding out about the alternative explantions.\n(Partly lack of time, due to lots of things on plate.)\n> >\n> What you are describing there springs from the\n> theoretical treatment of the vdW interaction by\n> Fritz London [Trans. Faraday Soc. 33, 8-26\n> (1937)]. London\'s treatment of the interaction was\n> the first one which fitted the experimental facts\n> known at the time, and it described the electrons\n> using the Schrödinger equation. The electrons were\n> assumed to interact with the nuclei and with one\n> another via a 1/r potential which acted instantaneously.\n> >\nHeh. I see below that "instantaneous" didn\'t work out\nso well ("fixed up by putting in a retardation term").\nThere\'s another Thread around here where I was asking\nabout whether other claims of instantaneouty should be\nbelieved. Perhaps you can help?\nhttp://groups.google.com/groups?hl=en&lr=&threadm=clvtdr%24fdj%241%40pcls4.std.com&prev=/groups%3Fnum%3D25%26hl%3Den%26lr%3D%26group%3Dsci. physics.research\n> >\n> For teaching purposes it is necessary to describe the\n> origin of the energy in words. This is said to be the\n> interaction between fluctuations of the electrons.\n> However remember, the wave function of the electrons\n> does not fluctuate and the atoms as a whole have zero\n> expectation value of their external electric field.\n> >\nYes, from a distance whole atoms are neutral. But\n"up-close-and-personal" can be another story. Otherwise\n(obviously) there would be no van-der-Waals/Casimir force.\n> >\n<snip>\n> Almost as an afterthought, Casimir noted that if you had\n> parallel metal plates separated by large distances, the\n> interaction was independent of which particular metal\n> you used [H B G Casimir Proc. Kon. Ned. Akad. Wetensch.\n> B 51 (1948) 793] and could be considered to originate\n> from the energy of zero-point fluctuations of the\n> electromagnetic field.\n> >\nI\'ll snip the mystical stuff, too. Until proved otherwise,\nI accept the quantum fluctuations as being the same as a\n"uniform heat sink" from which no energy can be extracted,\nper 2nd Law of Thermodynamics. The current doubters are\nall trying to re-invent Maxwell\'s Demon (which was proved\nto take more energy to accomplish its task, than would be\ngained from the task).\n> >\nBut I still have questions. I mentioned in an earlier\nmessage something about a debate regarding the photons\nthat might be responsible for the Casimir Effect. In\nthat discussion the points were made (STRESSED) that\nthe Effect does not work for non-conductors, and that\nthere is a 4th-power formula describing the change in\nthe magnitude of the Effect. I\'d like to know, if the\nCasimir Effect is the same as the van der Waals force,\nhow those two items can be true. Because vdW is not\nconcerned the the metallic nature of nearby atoms (in\nplate form or otherwise), and electrical attractions\nare known to obey the inverse-SQUARE law. Thanks!\n> >\n<snip>\n> The third picture says that the energy of the\n> interaction comes from the attraction between\n> opposite charges. This is a lot less mysterious,\n> and the people attracted to physics by the\n> Copenhagen interpretation don\'t like it.\n> >\nI can imagine! But does it provide for that 4-power\nrelation mentioned above? (I see Uncle Al re-linked\nthat page I mentioned, where I thought he was\ndescribing mirrors made from nonconductors. I think\nthat what you would have to say about that could be\nquite interesting! Partly because I wondered if\nsuch plates -- if that is what Uncle Al is really\ndescribing -- would experience separate vdW and\nCasimir effects, combined!)\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>> zigoteau@yahoo.com (zigoteau) wrote:
> > vnemitz@pinn.net (vernonner3voltazim) wrote:
> > > zigoteau@yahoo.com (zigoteau) wrote:
> > >
> > > Firstly, Casimir carried out his calculations to try
> > > to explain measurements on colloids. The Casimir
> > > interaction *is* the van der Waals interaction,
<snip>
> > >
> > And here all these years went by with me thinking (as I
> > once read somewhere) that van der Waals forces were
> > caused by the electrons of one atom temporarily
> > "seeing" the protons of another atom.
<snip>
> >
> Well, that description is not wrong. One thing you have
> to get used to in physics is that a given phenomenon
> can often be described in a number of ways, apparently
> quite different from one another.
> >
Oh, I don't have a problem with that. My problem
is finding out about the alternative explantions.
(Partly lack of time, due to lots of things on plate.)
> >
> What you are describing there springs from the
> theoretical treatment of the vdW interaction by
> Fritz London [Trans. Faraday Soc. 33, 8-26
> (1937)]. London's treatment of the interaction was
> the first one which fitted the experimental facts
> known at the time, and it described the electrons
> using the Schrödinger equation. The electrons were
> assumed to interact with the nuclei and with one
> another via a 1/r potential which acted instantaneously.
> >
Heh. I see below that "instantaneous" didn't work out
so well ("fixed up by putting in a retardation term").
There's another Thread around here where I was asking
about whether other claims of instantaneouty should be
believed. Perhaps you can help?
http://groups.google.com/groups?hl=en&lr=&threadm=clvtdr%24fdj%241%40pcls4.std.com&prev=/groups%3Fnum%3D25%26hl%3Den%26lr%3D%26group%3Dsci. physics.research
> >
> For teaching purposes it is necessary to describe the
> origin of the energy in words. This is said to be the
> interaction between fluctuations of the electrons.
> However remember, the wave function of the electrons
> does not fluctuate and the atoms as a whole have zero
> expectation value of their external electric field.
> >
Yes, from a distance whole atoms are neutral. But
"up-close-and-personal" can be another story. Otherwise
(obviously) there would be no van-der-Waals/Casimir force.
> >
<snip>
> Almost as an afterthought, Casimir noted that if you had
> parallel metal plates separated by large distances, the
> interaction was independent of which particular metal
> you used [H B G Casimir Proc. Kon. Ned. Akad. Wetensch.
> B 51 (1948) 793] and could be considered to originate
> from the energy of zero-point fluctuations of the
> electromagnetic field.
> >
I'll snip the mystical stuff, too. Until proved otherwise,
I accept the quantum fluctuations as being the same as a
"uniform heat sink" from which no energy can be extracted,
per 2nd Law of Thermodynamics. The current doubters are
all trying to re-invent Maxwell's Demon (which was proved
to take more energy to accomplish its task, than would be
gained from the task).
> >
But I still have questions. I mentioned in an earlier
message something about a debate regarding the photons
that might be responsible for the Casimir Effect. In
that discussion the points were made (STRESSED) that
the Effect does not work for non-conductors, and that
there is a 4th-power formula describing the change in
the magnitude of the Effect. I'd like to know, if the
Casimir Effect is the same as the van der Waals force,
how those two items can be true. Because vdW is not
concerned the the metallic nature of nearby atoms (in
plate form or otherwise), and electrical attractions
are known to obey the inverse-SQUARE law. Thanks!
> >
<snip>
> The third picture says that the energy of the
> interaction comes from the attraction between
> opposite charges. This is a lot less mysterious,
> and the people attracted to physics by the
> Copenhagen interpretation don't like it.
> >
I can imagine! But does it provide for that 4-power
relation mentioned above? (I see Uncle Al re-linked
that page I mentioned, where I thought he was
describing mirrors made from nonconductors. I think
that what you would have to say about that could be
quite interesting! Partly because I wondered if
such plates -- if that is what Uncle Al is really
describing -- would experience separate vdW and
Casimir effects, combined!)
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