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	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=895:_Teaching_Physics&amp;diff=410033</id>
		<title>895: Teaching Physics</title>
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		<summary type="html">&lt;p&gt;2601:447:C382:BF0:A115:E92E:3BB0:76D: /* A similar, but slightly different explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 895&lt;br /&gt;
| date      = May 6, 2011&lt;br /&gt;
| title     = Teaching Physics&lt;br /&gt;
| image     = teaching_physics.png&lt;br /&gt;
| titletext = Space-time is like some simple and familiar system which is both intuitively understandable and precisely analogous, and if I were Richard Feynman I'd be able to come up with it.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
The comic makes fun at the idea that physics is only interesting because teachers use interesting analogies, despite the fact that they are over-simplified and don't help when more complex theory is taught. The comic refers to the classic &amp;quot;Ball on a rubber sheet&amp;quot; metaphor as a way to explain {{w|general relativity}}, even though the metaphor breaks when trying to explain what causes gravity. The fourth panel highlights this with the statement that space-time is a {{w|Einstein field equations|set of equations}}, for which no analogy can fully explain.&lt;br /&gt;
&lt;br /&gt;
The title text continues the teacher's frustration with coming up with an analogy by stating that there is some analogy that is both understandable and precise, and if he were the famous physicist/teacher {{w|Richard Feynman}} he could come up with it. Professor Feynman was famous for his physics lectures and their ability to both entertain and educate his students, from the beginning student to the more advanced graduate students. Recordings of his lectures are still available and applicable to today's audience.&lt;br /&gt;
&lt;br /&gt;
Another comic shows how to play with this [[1158: Rubber Sheet]].&lt;br /&gt;
&lt;br /&gt;
==A similar, but slightly different explanation==&lt;br /&gt;
&lt;br /&gt;
Laws of physics (with General Relativity being one example) are expressed mathematically; any description in English is by necessity an analogy.  To really understand the physics behind it, you have to understand the mathematics, since any analogy will always fail at some level.  However, many people find mathematics to be boring and the analogies to be much more interesting.  The strip highlights the irony of finding the incorrect explanation (the analogy) interesting and the real explanation (the mathematics) boring.&lt;br /&gt;
&lt;br /&gt;
The title text refers to Feynman's extraordinary ability to find really, really good analogies, and in some cases create an intuitive way to understand a complex concept which is exact and precise.  One of the best examples of the latter is {{w|Feynman Diagram}}s, which allows people to visualize and intuitively understand extremely complex mathematical expressions (specifically, S-matrix elements that form transition amplitudes in quantum field theory) without losing any of the precision or correctness.  Unfortunately, nothing like that exists for black holes.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:Cueball: Understanding gravity: Space-time is like a rubber sheet. Massive objects distort the sheet, and-&lt;br /&gt;
:Student: Wait.&lt;br /&gt;
&lt;br /&gt;
:Student: They distort it because they're pulled down by... what?&lt;br /&gt;
&lt;br /&gt;
:Cueball: ''sigh''&lt;br /&gt;
&lt;br /&gt;
:Cueball: Space-time is like this set of equations, for which any analogy must be an approximation.&lt;br /&gt;
:Student: ''Boooooring.''&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Multiple Cueballs]]&lt;/div&gt;</summary>
		<author><name>2601:447:C382:BF0:A115:E92E:3BB0:76D</name></author>	</entry>

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