<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr"><span>Andrew,</span></div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr"><span><br></span></div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr">No matter how difficult or challenging to implement, to justify and perhaps limit the possibilitieswe need 21st century level experiments instead of just 20th century experiments. Any theory should propose an experiment. </div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr"><br></div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr">Wikipedia is not a great source, just a good quick view. As knowledge experts I believe we need to quickly check and move on from Wiki. However, it is the public encyclopedia so if it is lacking, then we should be able to make note of it in our lectures and perhaps have it corrected. And occasionally, wiki hits a research home run with a nice diagram, a list of references or something else of value. I think of Wiki as an index card I didn't write and need to verify at the source. </div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr"><br></div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr">On the professional level, I pull from a variety of sources defined more by Physics Review Letters than any other source. SPIE clearly is authoritative as well. ArXiv provides a fair amount of sources as well. I am cautiously optimistic when I read translations of Russian and Chinese journals provide a fair amount of value as well as those from specific universities around the world. </div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr"><span><br></span></div><div id="yui_3_16_0_1_1429589532807_4459" dir="ltr" class="" style="">So, given that we have entered a period where the papers are being written and reviewed, I'll leave wiki to the reader and focus on providing PRL or Arxiv sources. </div><div class="" style="" id="yui_3_16_0_1_1429589532807_4795"><br class="" style=""></div><div class="" style="" id="yui_3_16_0_1_1429589532807_4795" dir="ltr">David</div><br> <blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; margin-top: 5px; padding-left: 5px;" id="yui_3_16_0_1_1429589532807_4464"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1429589532807_4463"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1429589532807_4462"> <div dir="ltr" id="yui_3_16_0_1_1429589532807_4461"> <hr size="1" id="yui_3_16_0_1_1429589532807_4460"> <font size="2" face="Arial" id="yui_3_16_0_1_1429589532807_4465"> <b id="yui_3_16_0_1_1429589532807_4544"><span style="font-weight:bold;" id="yui_3_16_0_1_1429589532807_4543">From:</span></b> Andrew Meulenberg <mules333@gmail.com><br> <b><span style="font-weight: bold;">To:</span></b> Nature of Light and Particles - General Discussion <general@lists.natureoflightandparticles.org> <br><b><span style="font-weight: bold;">Cc:</span></b> David Mathes <davidmathes8@yahoo.com>; Kyran Williamson <kyran_williamson@hotmail.com>; Philipp Steinmann <philipp.steinmann@gmail.com>; Nick Bailey <nick@bailey-family.org.uk>; Anthony Booth <abooth@ieee.org>; Ariane Mandray <ariane.mandray@wanadoo.fr>; Manohar . <manohar_berlin@hotmail.com> <br> <b id="yui_3_16_0_1_1429589532807_4546"><span style="font-weight: bold;" id="yui_3_16_0_1_1429589532807_4545">Sent:</span></b> Monday, April 20, 2015 8:04 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [General] Casimir and van der Waals<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1429589532807_4466"><br><div id="yiv3683381261"><div dir="ltr" id="yui_3_16_0_1_1429589532807_4469"><div id="yui_3_16_0_1_1429589532807_4468"><div id="yui_3_16_0_1_1429589532807_4467">Dear John W,<br><br></div><div id="yui_3_16_0_1_1429589532807_4470">Re: Van der Waals and Casimir. </div><div id="yui_3_16_0_1_1429589532807_4471"><br></div>I know that you didn't have space for the whole story and I do not think it rare that two different models describing the same mechanism turn out to be identical (e.g. Heisenberg & Schrodinger representations); nevertheless, it is a very interesting story. I do not know enough about either Casimir or vdW mechanisms to see thru the details, but Martin's comment about the zeroth-order approximation of the material addressed one of my questions. How did dielectrics compare with conducting plates (e.g. just sequentially reversing orientation of 1st surface mirrors after comparing blanks and double-sided mirrors)? I might think that test could provide a 1st order effect. The next step in this direction would be to change the environments to one better known. What happens in the two models and experiment (with the 1st surface mirror sequence) when the external environment is dominated by introduction of mono-energetic light from a laser? I believe this is a case where the two models would also differ.<br><br></div><div id="yui_3_16_0_1_1429589532807_4472">David's suggestion of testing spin (and other dynamic) effects is good, but more difficult to implement.<br><br></div><div id="yui_3_16_0_1_1429589532807_4473">I don't have time to look into these details, but I would also love to have a quick look at conclusions from a recent survey source more definitive than Wikipedia. However, that source does compare the more-narrowly-defined vdW & Casimir effects as "The <u>London</u>-van der Waals forces are related to the Casimir effect for dielectric media, the former being the <u>microscopic</u> description of the latter bulk property."</div><div id="yui_3_16_0_1_1429589532807_4474"><br></div><div id="yui_3_16_0_1_1429589532807_4475">Andrew<br></div>_________________________________________<br><div id="yui_3_16_0_1_1429589532807_4817"><div id="yui_3_16_0_1_1429589532807_4816"><br>Right ....<br>
<br>Van der Waals and Casimir. <br>
<br>
There are hundreds of published, peer reviewed, papers out there
purporting to have measured the Casimir force. I have not read all of
them and some of them may well be right. Many of these are "me too"
papers confirming someone else's results. Others are papers
showing an agreement between the forces measured and the calculations
for the Casimir force.<br>
<br>
So why, then, do I think that most of these guys have been wasting their time?<br>
<br>
That is down to a couple of friends of mine Philipp Steinmann and John
Weaver (cheers)- as well as many other excellent people in
nanoelectronics in Glasgow who made the experiment possible in the first
place. I'll copy this to Philipp for comment - though
he now works in another field. It also comes from, for me, to some
understanding of the basic physics due (partly) to an excellent
collaboration with Casimir himself many years ago.
<br>
<br>
The Glasgow guys are seriously excellent set of experimental physicists -
with the proper integrity to see things for what they truly are.
Casimir was a pleasure to meet and work with. One of the smartest people
it has been my pleasure to interact with.<br>
<br>
Yes, indeed, the van der Waals force dependence depends on the configuration, as you say David. So does the Casimir force.
<br>
<br>
John Weaver, Philipp and others, considered measuring the Casimir force
using their atomic force microscope (AFM), one of the best in the world
at the time. I'm telling you - these guys are good. Easy experiment -
plenty of sensitivity - direct measurement
-no messing around. Just do it. Indeed, the experiment showed, as have
countless others, a force as predicted by Casimir. Job done? no!<br>
<br>
What about other possible forces such as the Van der Waals force?<br>
<br>
I think it was Philipp who did most of the work here (corrections
guys?). He calculated it and found it was virtually the same as the
Casimir force, with the same dependence and the same constants.<br>
<br>
Consider, for a moment, the two scenarios ...<br>
<br>
One, Casimir. Two parallel mirrors in a vacuum. Excluded QM modes.<br>
<br>
Two. vd Waals. Two parallel conductors in a vacuum. Electron wave-function overlaps.<br>
<br>
Oh dear: mirrors are conductors ...<br>
<br>
Think about it: it is the same physical problem. Different boundary conditions. Same answer.
<br>
<br>
Surprise?<br>
<br>
These guys had the integrity to drop this at that point. Qudos. Question is, can one trust others to do as good a job?<br>
<br>
Now, any paper on "measuring the Casimir force" had, for me, better do a
damn good job on the van der Waals force as well. There may be such a
paper now. This was not the case for the first few dozen I looked at
though. Phillipp? John? anyone else? Please
let me know.<br>
<br>
Regards, John W (the other one).<br></div></div></div></div><br><br></div> </div> </div> </blockquote> </div></body></html>