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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hmm,<br>
<br>
Had seen the original nature physics paper on this. The Maxwell equations in free space do not allow for interactions, self evidently, as they are linear and first order in the fields. The extra thing that comes in in QED for light-light scattering is the so
called "box" diagram with four vertices. For this to be significant you need really high energy gammas. The experiment has a LOWER cutoff of 6 GeV!. It is nonsense to suggest that there would be a problem in observational astrophysics at much lower energies
as for low energy photons you can pretty much ignore this. Clearly, the universe is pretty clear for ordinary light. The interesting thing about the ATLAS experiment is that it has more di-photon events than you would expect even adding in all known physics.
This is quite a lot more than you would see with just QED as there are several QCD channels that contribute to gamma pairs as well. You need to look at the Nature Physics article, or the PRL on the theory (ref 20 I think) as the physics world one is too low
level to say much. The photons here are cut to be very nearly real. The total effect, over and above QCD and QED is only 4 and a bit sigma though, and we have all seen those go away. Also, looking at it, I'm not convinced all the possible channels have been
taken into account. This would be nice for my new theory though, as one would expect to see extra diphotons from the mass-mass channel.<br>
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Regards, John.<br>
<br>
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<div id="divRpF13942" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>From:</b> General [general-bounces+john.williamson=glasgow.ac.uk@lists.natureoflightandparticles.org] on behalf of Roychoudhuri, Chandra [chandra.roychoudhuri@uconn.edu]<br>
<b>Sent:</b> Sunday, August 27, 2017 5:19 PM<br>
<b>To:</b> Nature of Light and Particles - General Discussion<br>
<b>Cc:</b> Professor Jishnu Dey<br>
<b>Subject:</b> Re: [General] light light interactions<br>
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<p class="MsoNormal"><span style="font-size:14.0pt">Andrew: </span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> I have been already communicating with my MS classmate in India on this issue. I feel very sad that we have been trying to publicize very complex high energy phenomena as proof of the generic light-by-light
scattering! These experiments always involve the <b><i>presence</i></b> of high energy particles and/or nuclei (and sometimes unverifiable virtual photons) in some form or other. Sorry! These kinds of “rapid communications” appears to have more political
agenda than serious and honest scientific communications. We are dangerously moving towards establishing “Twitter Physics Culture” for our younger generations!</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> <b><i>All currently working theories are necessarily incomplete as they have been formulated based upon incomplete information about the universe. The job of advanced thinkers is to proactively discover
the limits of the “working” theories so our knowledge of the working rules behind the universe is allowed to evolve continuously instead of staying stagnant.</i></b></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> Let us remind ourselves the experience of our daily lives. We could not have evolved if we were not able to see each other unperturbed in spite of all the other innumerable light signals randomly crossing
through the line of sight we focus on. Al visible light beams in nature and laser beams in laboratories pass through each other unperturbed. This is the visible band.
</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> We could not keep on receiving steady radio and video signals were it not for the reality that these EM waves also pass through each other unperturbed. These are the radio and the microwave bands.</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> This is Non-Interaction of Waves (NIW), which I have demonstrated through many re-producible laboratory experiments. [“Causal Physics”, CRC, 2014]. Entire observational Astrophysics would have been producing
unstable date were it not for the NIW-property of all EM waves. </span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> Even Julian Schwinger, apparently in one of his papers, acknowledged that classical Electromagnetism (lower energy and frequency compared to Gamma ray) does not allow for the “photon-photon” interactions
in the linear domain.</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> I have lost track of this paper. I will appreciate if anybody can send me the correct reference.</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Sincerely,</span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Chandra.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt; font-family:"Calibri",sans-serif; color:#1F497D"> </span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt; font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt; font-family:"Calibri",sans-serif"> General [mailto:general-bounces+chandra.roychoudhuri=uconn.edu@lists.natureoflightandparticles.org]
<b>On Behalf Of </b>Andrew Meulenberg<br>
<b>Sent:</b> Sunday, August 27, 2017 10:39 AM<br>
<b>To:</b> Nature of Light and Particles - General Discussion <general@lists.natureoflightandparticles.org>; Andrew Meulenberg <mules333@gmail.com><br>
<b>Cc:</b> robert hudgins <hudginswr@msn.com><br>
<b>Subject:</b> [General] light light interactions</span></p>
<p class="MsoNormal"> </p>
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<p class="MsoNormal">For those who argue against light-light interactions</p>
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<p class="MsoNormal"><br>
<a href="http://physicsworld.com/cws/article/news/2017/aug/18/light-is-seen-to-scatter-off-light" target="_blank">http://physicsworld.com/cws/article/news/2017/aug/18/light-is-seen-to-scatter-off-light</a></p>
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