explain xkcd:Sandbox
Welcome to the explain xkcd wiki!
We have an explanation for all 3256 xkcd comics, and only 46 (1.4%) are incomplete. Help us finish them!
Latest comic
| Particle Census |
 Title text: Remember, your answers to the physics census are confidential; we will not be issuing Pauli exclusion principle citations. |
Explanation
|
This is incomplete: This page was created at an INDETERMINITE TIME. Don't remove this notice too soon. If you can fix this issue, edit the page! |
This comic references the Heisenberg uncertainty principle of quantum mechanics. Put simply, it states that there's a limit to how precisely we can know both the position and momentum of a particle — the more precisely 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.
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 decennial 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, as there are a lot of particles in the universe, and many are quite far away.[citation needed] And unless the particles happen to be at absolute zero, they will be moving, potentially quite fast. So it would be a needlessly difficult census.
In the third panel, someone speaks up and is worried about what they will do with the particles in the potential “disruption”. Randomly taking someone’s particles and relocating them would be considered unpleasant,[citation needed] even if you tell them where the particles are going.
If indeed all particles locations was determined (as exactly as possible) it would have to be done using very high energi particles (where would they then be?), and thus all the particles measured would after wards move very fast (less than the speed of light of course, but close to it). Thus everything (and everyone) would be destroyed. So the concern voiced is very fair, but of course unnecessary as it would not be possible to perform the task that Megan claims will happen.
The title text refers to the Pauli exclusion principle, which states that no two fermions — types of particles that include all ordinary matter — can occupy the same quantum state. As the results of the census are confidential, physics officials will not use it to determine whether to issue citations for particles that violate the exclusion principle. This confuses physical laws, which describe how the universe works and by their nature cannot be violated, with societal laws, which declare what is allowed or required by the government.
Transcript
- [Megan is standing behind a lectern, addressing an unseen audience.]
- Megan: Remember, Tuesday is the decennial particle census.
- Megan: Physicists will be recording the location of all particles in the universe.
- [Zoom out to show Megan is on a podium behind the lectern. She holds one hand, palm up, out towards the still unseen audience]
- Megan: Of course, this will cause their momenta to become indeterminite, so please plan for some disruption.
- [The same scene with Megans hands held down. A voice comes from off-panel at the left through a star burst at the edge of the panel.]
- Audience member [off-panel]: Wait, disruption? Where will my particles go?
- Megan: No one can say, but you'll know exactly where they were.
Trivia
- When this comic was uploaded the normal sized image was incorrectly 2x size. It kept showing up at 2x size on unixkcd for awhile.
- "Indeterminate" is spelt "indeterminite" in the second panel text.
Add comment 
Create topic (use sparingly) 
Refresh Discussion
Make changes, try things out, or just have fun with the wiki here! Just leave everything above the line alone, please.
This is a test. PoolloverNathan[stalk the blue seas] 20:48, 16 March 2021 (UTC)
- This is not. —While False (museum | talk | contributions | logs | rights | printable version | page information | what links there | related changes | Google search | current time: 07:45) 18:38, 17 November 2022 (UTC)
- A foreign student asked me to help fight against his math teacher. That was unusual. He was in that class for just a couple of weeks. The teacher's phone number was sent to me. The student asked me to spam-call the teacher. 172.71.155.55 22:58, 18 September 2023 (UTC)
here i'm just messing around in html, ignore this
furhhfghure guyrburgryhuyvfr "rvhru"
interesting way of writing quotations xd
- hmmm this one of putting "<p>" in a line break will come in handy for when i want it to start at the same place than the first line
edit: da hek did that "</div>" come from An user who has no account yet (talk) 14:14, 13 October 2023 (UTC)
hi uh its hard to get here.
is this a reference to undocumented feature??? hmm... this is interesting.
108.162.241.216 02:05, 23 November 2023 (UTC)
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
|
|
Soup |
|---|
yum yum [citation needed]
Hiuiedeixgeyceiyedhcdiedcve {{trout}}
This is the leaderboard:Last 7 days (Top 50) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
<a href=" [AT THE JULY 28TH MEETING][tab] "Cancel the meeting! Our cover is blown."> More testing: hello doesthiswork (yesitdoes) This isn't a good name (talk) 22:44, 28 January 2026 (UTC)
hi 164.58.172.158 14:21, 23 February 2026 (UTC)
What is this?????????????????????? King Pando (talk) 04:25, 10 March 2026 (UTC)
Hello 107.1.219.44 19:29, 29 April 2026 (UTC) Add comment View comic discussionNew here?
Last 30 days (Top 10) |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
You can read a brief introduction about this wiki at explain xkcd. Feel free to create an account and contribute to the wiki! We need explanations for xkcd comics, characters, What If? articles, and everything in between. If it is referenced in an xkcd comic, it should be here.
- If you're new to wiki editing, see the explain xkcd:Editor FAQ for a specific guidance to this wiki and the more general help on how to edit wiki pages. There's also a handy wikicode cheatsheet.
- Discussion about the wiki itself happens at the Community portal.
- You can browse the comics from the list of all comics or by navigating the category tree at Category:Comics.
- The incomplete explanations are listed here. Feel free to help out by expanding them!
Rules
Don't be a jerk!
There are a lot of comics that don't have set-in-stone explanations; feel free to put multiple interpretations in the wiki page for each comic.
If you want to talk about a specific comic, use its discussion page.
Please only submit material directly related to xkcd and, of course, only submit material that can legally be posted and freely edited. Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.
If you need assistance from an admin, post a message to the Admin requests board.
