https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=212.133.41.67 2026-05-20T00:21:34Z User contributions MediaWiki 1.30.0 https://www.explainxkcd.com/wiki/index.php?title=3247:_Particle_Census&diff=413037 2026-05-18T19:28:45Z

<p>212.133.41.67: /* Trivia */ spelling</p> <hr /> <div>{{comic<br /> | number = 3247<br /> | date = May 18, 2026<br /> | title = Particle Census<br /> | image = particle_census_2x.png<br /> | imagesize = 651x272px<br /> | noexpand = true<br /> | titletext = Remember, your answers to the physics census are confidential; we will not be issuing Pauli exclusion principle citations.<br /> }}<br /> <br /> ==Explanation==<br /> {{incomplete|This page was created at an UNCERTAIN TIME. Don't remove this notice too soon.}}<br /> <br /> This comic references the {{w|Heisenberg uncertainty principle}} of quantum mechanics. Put simply, it states that we can't know both the position and momentum of a particle -- the more accurately we know one, the less we know the other. [[Megan]] says they're taking a census of the positions of all particles in the universe, so they'll be known precisely; therefore, all their momenta will be unknowable. And by the time we use the census results we won't know where any of the particles are, we'll just know where they were at the instant their positions were recorded by the census.<br /> <br /> In the United States, the Constitution mandates that a population census of people living in all the states be taken every ten years. This is primarily for the purpose of apportioning representatives to Congress, but it has come to be used for many other demographic purposes. There's no legal requirement for a decenial physics census; if physicists want to do this, it's their own decision. However, it's not really possible to measure the positions of ''all'' particles in the universe - Because there are a lot of particles in the universe, &amp; many are quite difficult to reach.{{citation needed}} As well as that, saying where some of the particles are, at least when you get to more spacebound areas, would be difficult too. So a needlessly difficult census.<br /> <br /> The title text refers to the {{w|Pauli exclusion principle}}. This states that no two {{w|fermions}} can occupy the same quantum state. As the results of the census are confidential, physics officials will not use it to determine if any particles are violating it and issuing citations. This confuses physical laws, which describe how the universe works, with societal laws, which state what is allowed or required by the government.<br /> <br /> ==Trivia==<br /> When this comic was uploaded the normal sized image [https://web.archive.org/web/20260518185623/https://xkcd.com/3247/ was incorrectly 2x size].<br /> <br /> Additionally, &quot;indeterminate&quot; is spelt &quot;indeterminite&quot; in the second panel text.<br /> <br /> ==Transcript==<br /> {{incomplete transcript|Don't remove this notice too soon.}}<br /> :[First Panel. Megan is standing at a lectern, presumably talking to an audience.]<br /> <br /> :Megan: Remember, Tuesday is the decennial particle census.<br /> <br /> :Megan: Physicists will be recording the location of all particles in the universe.<br /> <br /> :[Second Panel. Zooms out to show the stage Megan is on]<br /> <br /> :Megan: Of course, this will cause their momenta to become indeterminite, so please plan for some disruption.<br /> <br /> :[Third Panel. An audience member pipes up from off-panel.]<br /> <br /> :Audience member: Wait, disruption? Where will my particles go?<br /> <br /> :Megan: No one can say, but you'll know ''exactly'' where they were.<br /> <br /> {{comic discussion}}&lt;noinclude&gt;</div>

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