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		<id>https://www.explainxkcd.com/wiki/index.php?title=3085:_About_20_Pounds&amp;diff=376510</id>
		<title>3085: About 20 Pounds</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3085:_About_20_Pounds&amp;diff=376510"/>
				<updated>2025-05-06T16:25:46Z</updated>
		
		<summary type="html">&lt;p&gt;Andygeers: Typo&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 3085&lt;br /&gt;
| date      = May 5, 2025&lt;br /&gt;
| title     = About 20 Pounds&lt;br /&gt;
| image     = about_20_pounds_2x.png&lt;br /&gt;
| imagesize = 666x278px&lt;br /&gt;
| noexpand  = true&lt;br /&gt;
| titletext = In addition to gravity, burritos interact through the strong, weak, and electromagnetic forces, which is believed to be a major contributor to their popularity.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|Created by a £20 PARTICLE. Are there any missing categories? Don't remove this notice too soon.}}&lt;br /&gt;
&lt;br /&gt;
The nature of {{w|dark matter}} is a significant unsolved problem in physics. In an effort to solve the problem, [[Cueball]] and [[Ponytail]] appear to have used occult methods to conjure a supernatural {{w|oracle}} (something which would present its own challenges to our understanding of the physical world) in order to demand an answer from it. There may be a pun here, in that they are using 'dark magic' to communicate with something from the 'dark realm' on the assumption that it will know about dark matter. However, the word 'dark' in this context simply means that we do not know how to observe it; dark matter is not evil or satanic{{cn}} (though [[Randall]] may consider it [[:Category:Comics with cursed items|cursed]]).&lt;br /&gt;
&lt;br /&gt;
In general, not all forces interact with all particles; indeed, {{w|gravity}} is the only force that is (believed to) interact with everything. If a force doesn't interact with a particle, then its existence cannot be observed via disturbances in that force. In particular, something that doesn't interact with electromagnetism cannot be 'seen', as photons will pass through it completely unaffected.&lt;br /&gt;
&lt;br /&gt;
Even {{w|neutrino}}s -- famous for interacting with ''almost'' nothing -- still in fact interact via the {{w|weak force}}, allowing them to be detected with sufficiently large tanks of dense material (as most atoms do in fact interact with the weak force, however weakly). A particle that interacts with ''nothing'' except gravity, could only be detected by a gravitational telescope.&lt;br /&gt;
&lt;br /&gt;
However, even if a particle does interact via a given force, an interaction is only possible if energy is conserved. If dark matter is entirely due to a single kind of particle, and the fundamental mass of that particle is ''twenty pounds'' -- an absolutely ludicrous amount of energy for particle physics -- then any interaction would (roughly speaking) have to involve an equally ludicrous amount of other particles being in exactly the right place and time, a coincidence that could easily reach &amp;quot;never in the history of the universe&amp;quot; levels. (By comparison, the {{w|top quark}}, otherwise the heaviest single particle with a mass over a hundred times that of the proton, is still nevertheless around a tenth of a trillionth of a trillionth of a pound.)&lt;br /&gt;
&lt;br /&gt;
Under more normal circumstances, we might still hope to observe the properties of the particle via creating it ourselves under controlled laboratory conditions. But again, there is no reasonable way to focus the energy required into a single particle interaction -- the LHC, for example, peaks at about ten thousand times the mass of the proton, a solid billion times less energy than required -- so that's out too.&lt;br /&gt;
&lt;br /&gt;
Finally, despite all this, twenty pounds is also much too ''small'' to be detectable via gravitational interaction -- its {{w|Perturbation_(astronomy)|influence on the orbits of planets}}, say, or the strength of its {{w|gravitational lensing}} effect, will be entirely negligible. Thus, in the scenario posed by the comic, there is essentially no plausible way to observe more about dark matter while on Earth.&lt;br /&gt;
&lt;br /&gt;
The oracle proceeds to break expectations by suggesting that Ponytail and Cueball go out for {{w|burrito}}s, something generally considered less than scientific. However, given the apparent futility of continuing to try to investigate dark matter, going out for burritos is precisely as productive as any other approach (i.e. &amp;quot;not at all&amp;quot;).&lt;br /&gt;
 &lt;br /&gt;
When the title text observes that burritos interact through the strong, weak, and electro-magnetic forces, it presumably means that they can be seen, smelt, tasted, and their texture sensed, as well as producing digestive effects, and that all of these effects generally tend to be pleasant, hence contributing to their popularity.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Cueball and Ponytail are standing in front of a pentacle with lit candles at the corners. A black sphere, the oracle, is floating above the middle of the pentacle.]&lt;br /&gt;
:Ponytail: Dear oracle,&lt;br /&gt;
:Ponytail: What is the nature of dark matter?&lt;br /&gt;
:Oracle: It's about 20 pounds.&lt;br /&gt;
&lt;br /&gt;
:[Close up of oracle]&lt;br /&gt;
:Off-panel: What?&lt;br /&gt;
:Oracle: Dark matter is a particle. It weighs about 20 pounds.&lt;br /&gt;
:Oracle: It only interacts through gravity.&lt;br /&gt;
&lt;br /&gt;
:[Same view as first panel]&lt;br /&gt;
:Cueball: Only gravity, huh?&lt;br /&gt;
:Cueball: So none of our experiments are really going to tell us any more about it, then.&lt;br /&gt;
:Oracle: Afraid not.&lt;br /&gt;
&lt;br /&gt;
:[Same view as first and third panels, except Cueball lifted his forearm.]&lt;br /&gt;
:Cueball: So what do we do?&lt;br /&gt;
:Oracle: You should go out for burritos.&lt;br /&gt;
:Ponytail: How will that help?&lt;br /&gt;
:Oracle: Well,&lt;br /&gt;
:Oracle: Burritos are pretty good.&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&amp;lt;noinclude&amp;gt;&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:Comics featuring Ponytail]]&lt;br /&gt;
[[Category:Physics]]&lt;br /&gt;
[[Category:Food]]&lt;br /&gt;
&amp;lt;/noinclude&amp;gt;&lt;/div&gt;</summary>
		<author><name>Andygeers</name></author>	</entry>

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