Editing Appendix/QED

=Feynman's Path-Integral Formulation (QED)=

==A Couple of Relevant YouTube Videos==

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<b>YouTube</b> video:<br/>[https://www.youtube.com/watch?v=P9nPMFBhzsI Richard P. Feynman's 1979 Lectures <br />at the University of Auckland, NZ]
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<b>YouTube</b> video:<br/>[https://www.youtube.com/watch?v=UWuhMJZaiZM Physics With Elliot]
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[[File:FeynmanQEDlectures.png|300px|Feynman's 1979 Lectures]]
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[[File:PhysicsWithElliot.png|300px|Physics with Elliot]]
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[https://www.amazon.com/QED-Strange-Princeton-Science-Library/dp/0691164096/ref=sr_1_1?crid=1ADBUJG30AKMM&dib=eyJ2IjoiMSJ9.h8T7MwXbLQ08ID92udAhT1-50my9jd3nJw_2uq_xddWIwGurCHdI-oacYZ8DYMgoeifwfSOkGWh6qvfeFYpBgxryz5rmZ_CXORiUd2asVOyvP9kfTV5_BLZfcKgkOwt5bxHCdORlMptg2GYSdrD68riSRagC6JLhDzHr96BY7_14FQnqAZpVnwwnr2kcd_Qj.tiVQd_494Q652oUOPpy1DwZzpSn3dW1_29r_VJWwVzk&dib_tag=se&keywords=qed+the+strange+theory+of+light+and+matter&qid=1743344383&sprefix=strange+theory+of+%2Caps%2C110&sr=8-1 Book]<br />resulting from Auckland lectures<br /><b>QED: The Strange Theory of Light and Matter</b>
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==Figures Similar to Feynmann's Fig. 24==

Here are a few figures that we generated (in Excel) to explain Fig. 24 (on page 43) of [https://www.amazon.com/QED-Strange-Princeton-Science-Library/dp/0691164096/ref=sr_1_1?crid=1ADBUJG30AKMM&dib=eyJ2IjoiMSJ9.h8T7MwXbLQ08ID92udAhT1-50my9jd3nJw_2uq_xddWIwGurCHdI-oacYZ8DYMgoeifwfSOkGWh6qvfeFYpBgxryz5rmZ_CXORiUd2asVOyvP9kfTV5_BLZfcKgkOwt5bxHCdORlMptg2GYSdrD68riSRagC6JLhDzHr96BY7_14FQnqAZpVnwwnr2kcd_Qj.tiVQd_494Q652oUOPpy1DwZzpSn3dW1_29r_VJWwVzk&dib_tag=se&keywords=qed+the+strange+theory+of+light+and+matter&qid=1743344383&sprefix=strange+theory+of+%2Caps%2C110&sr=8-1 Feynmann's Book], hereafter, [<b>[[Appendix/References#QED|<font color="red">QED</font>]]</b>].

Following pp. 38-39 of [<b>[[Appendix/References#QED|<font color="red">QED</font>]]</b>], the upper  portion of our set of figures displays a mirror that, as labeled, extends from point "<b>A</b>" to point "<b>M</b>"; it is divided into 12 segments.  Above the mirror is a ''source'' <font color="maroon">"that emits light of one color (red) at very low intensity</font>"; the location of a ''detector'' is identified as well.  <font color="maroon">"&hellip; there are millions of ways a photon could go"</font> as it travels from the source to the detector:  <font color="maroon">"it could go down to the left-hand part of the mirror at "<b>A</b>"</font> &#8212; as indicated by a green arrow &#8212; <font color="maroon">or "<b>B</b>" (for example) and bounce up to the detector</font> &#8212; as indicated by a red arrow; <font color="maroon">it could bounce off &hellip; at "<b>G</b>"; or it could go down to the right-hand part at <b>K</b> or <b>M</b></font> &#8212; as indicated by a longer green aroow &#8212; and bounce up to the detector</font> (shorter red arrow).

<!-- [[File:QEDFig24PowerPoint01.png|600px|center|Figure 24 in QED]] -->
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<b>Figure 1</b><br />[[File:QEDfig24TrajectoriesComplete.png|600px|center|Figure 24 in QED]]
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Next, following pp. 41-42 of [<b>[[Appendix/References#QED|<font color="red">QED</font>]]</b>], <font color="maroon">"let's draw a little arrow for each way the [photon] could go"</font> as it travels from the source to the detector.   <font color="maroon">"Although it is safe to assume that the length of all the arrows will be nearly the same"</font> &#8212; the "amplitude" of each photon is the same &#8212; their directions will clearly differ because their timing is different &#8212; remember that the direction of a particular arrow is determined by the final position of an imaginary stop-watch that times a photon as it moves along that particular path."</font>

[[File:ArrowEnsemble-Pt1.png|800px|center|Arrow Ensemble Part 1]]


[[File:ArrowEnsemble-Pt2.png|800px|center|Arrow Ensemble Part 2]]

==Slit Aperture Instead of Mirror==

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<b>Figure 2</b>
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[[File:QEDfig24TrajectoriesPPT.png|700px|Fig24 Trajectories]]<br />
<b>Panel a:</b>  &nbsp; Same as Figure 1, but with fewer photon trajectories displayed.
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[[File:QEDmirror02PPT.png|300px|Mirror02]]<br />
<b>Panel b:</b> &nbsp; Positions of detector and source modified from Panel a.
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  <td align="center" width="33%">[[File:QEDslit02PPT.png|300px|Slit02]]<br />
<b>Panel c:</b> &nbsp; Mirror replaced by slit; position of source flipped to position such that light passes through the slit rather than bouncing off of mirror.
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[[File:QEDslit03PPT.png|300px|Slit03]]<br />
<b>Panel d:</b>&nbsp; If the source is a laser, then photon trajectories between the source and the slit are all <i>in phase with</i>, and parallel to one another.
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  <td align="center">[[File:QEDslit04LaserRotated.png|300px|Slit03]]</td>
  <td align="center" colspan="1" bgcolor="lightgreen">[[File:Aperture3.gif|350px|Chapter1Fig1]]</td>
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=See Also=


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  <li>[[Appendix/CGH/Preface|Computer-Generated Holography]]</li>
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