explain xkcd - User contributions [en]

Talk:3104: Tukey

2025-06-19T11:12:50Z

Itub:

i dont get this comic :( [[User:Broseph|Broseph]] ([[User talk:Broseph|talk]]) 20:42, 18 June 2025 (UTC)\

The main panel makes a joke that the figure of 110,000 years is precise but wildly wrong while that Tukey's birthday is "sometime this week" is vague but basically correct. The alt-text is most likely true (I haven't checked) because of leap years.
: I think you'll find it is 110.000, not 110,000 [[Special:Contributions/1.146.44.41|1.146.44.41]] 23:54, 18 June 2025 (UTC)
:: Maybe they live in that country mentioned in [[3102|the alt text of two comics ago]]. [[Special:Contributions/2601:647:8500:1E09:D4EE:315E:E684:A802|2601:647:8500:1E09:D4EE:315E:E684:A802]] 02:13, 19 June 2025 (UTC)
::: yes {facepalm}. I think I'll find I need to increase font size everywhere yet again so that "." Looks different from "," because I read 110 thousand and not the correct of 110 point 000. Not sure if the joke is different and is funny either way. It's ibuprofen* getting old but Saul Goodman because of the alternative. [[Special:Contributions/2607:FB91:164E:4264:ACA5:3DBE:8045:7E6B|2607:FB91:164E:4264:ACA5:3DBE:8045:7E6B]] 05:55, 19 June 2025 (UTC)
::: * Spellcheck suggested "ibuprofen." I don't know why or what I typed to. Love you [[Special:Contributions/2607:FB91:164E:4264:ACA5:3DBE:8045:7E6B|2607:FB91:164E:4264:ACA5:3DBE:8045:7E6B]] 06:00, 19 June 2025 (UTC)

The one day difference is probably because of the rules of leap years. Most century years (like 1800, 1900, 2100) do not have a leap year, but 2000 did have a leap year. Leap year placement is done to approximate Earth's ratio of 365.2422 days per year. Oh, wait. Tukey (1915-2000) and Randall (1984-2094) both lived through the 2000 leap year. So it must just be because Randall was born shortly after Feb 29 of 1984, whereas Tukey was born shortly before Feb 29 of 1916. So Tukey would have had 28 leap days vs. Randall's 27 leap days on their 110 year birthdays. [[Special:Contributions/134.134.139.69|134.134.139.69]] 21:09, 18 June 2025 (UTC)
:I hadn't read this, before I edited in my version of the explanation (and a few more things surrounding it). Yes, it's basically where the "spans of four years" lie within the whole 110 width. Tukey had one soon (within a year) of his 0th birthday and another just in time (just more than a year) before the 110th birthday. It'd work the same for any year-span that started on the same day on any similar ''Y mod 4'' type of year (1915, also 1911 or 1924), so long as you didn't let the range start before 1900 or finish later than 2100. It gives the same result for 1918+-4n, too, for the same 16th June date in other respects. But shift to the same date in 1916(+-4n) or 1917(+-4n), and it traverses one less leap-day. You can move the date around, of course. If you keep it the right side of the the last/Feb->1st/Mar boundary, as you do for Randall's DOB, then it's still faithfull (1984=1916+4n, where n=17). If you jump back into January or February, it'll become an honourary member of the prior year's thing, but not applicable.
:Anyway, Randall's Leap-pattern is two years adrift from Tukeys, which guarantees that his leap-day-count is one different. One way or another. (A one-year mod-difference would half the time be "in the same pairing" and the other half be "in the other pairing".)
:Though that only applies for relative ranges that are both entirely within-and-inclusive of 1/Mar/1900 to 28/Feb/2100. You'd have to add another Zeller-like term to the [Y mod 4] thing to 'adjust' if you went further out, and may be able to find two year-ranges that had daycounts ''two'' different from each other, I guess, as well as ones that might be the same even though being on mod4+2... But I leave that as an excercise to data-divers wanting to go beyond merely the two indidividuals that the comic specifies. (And don't forget the Julian-to-Gregorian conversion scheme/timing, if you start to encroach upon dates that (for a given locale) are further complicated by a 10-13 day (2, 3, 0 or 1) mod-shuffle. Not including those (e.g. Lithuania, etc) who jumped back out to Julian 'temporarily' again, just to [[2867: DateTime|further complicate matters]]. Ignoring any possibility of the non-400-year manifestation of the 100-year glitch that would warrant a minor additional detail) [[Special:Contributions/92.23.2.228|92.23.2.228]] 23:07, 18 June 2025 (UTC)

Note that this is not saying 110,000 (1.1e5) years, but 110.000 (1.1e2), which is in fact the correct number of years. The value has three digits after the decimal point to imply sub-year precision, which is seldom meaningful with birthdays. [[Special:Contributions/2403:5803:BF48:0:0:0:0:1|2403:5803:BF48:0:0:0:0:1]] 21:19, 18 June 2025 (UTC)
:0.001 years is about 8 hours, so you do need that many digits to be precise to the day. But then he approximates with "sometime this week" -- a week is about 0.02 years. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 21:33, 18 June 2025 (UTC)

Wow 🤯 [[no name|no name]] 02:00, 19 June 2025 (CEST)

One day younger, but exactly the same age in sidereal years (or epochal seconds). [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 01:29, 19 June 2025 (UTC)

For a moment there I thought that 110.000 was a binary number, chunked every three digits to make it easier to convert to octal. But the number comes to 48 decimal (60 octal), which is clearly not enough for Tukey's age! --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:12, 19 June 2025 (UTC)

Talk:3101: Good Science

2025-06-12T11:03:28Z

Itub:

Should I find it comforting that, faced with "ammonium hydroxide", the student(?) decodes that as basically just "ammonia"? I mean, there are differences between anhydrous and hydrated versions, but it implies a certain amount of relevent scientific knowledge. If I mentioned "whateverium phlobotomide", the uninitiated would (as well as maybe stumbling over any unfamiliar parts of the name) probably be blind to it potentially being just a technical variation of the ''essential'' part of the name. Or, to put it another way, the technobable involved if you were to be told that all the dangerous dihydrogen monoxide had been swapped out for hydrogen hydroxide. (Or that it had been even more dangerous by introducing some trace amounts of nullanol.) [[Special:Contributions/92.23.2.228|92.23.2.228]] 22:49, 11 June 2025 (UTC)
:When I studied chemistry, you would get an earful from the professor if you ever dared to utter the phrase "ammonium hydroxide", because ammonium hydroxide does not exist. It's not a molecule, and there's no crystalline ammonium hydroxide, either; what you have is aqueous ammonia, a small fraction of which gets protonated by water, forming some ammonium ions and some hydroxide ions. Calling that ammonium hydroxide would be akin to calling aqueous acetic acid "hydronium acetate". Perhaps that's why ''ammonia'' is in italics in the comic: to emphasize that the reply is meant as a correction. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:03, 12 June 2025 (UTC)

I'm thinking that there are two uses for rigour without curiosity. The explanation covers the professional motive: to have a career in producing good-looking results. There is also a political motive: to block a line of research, to prevent its results from gaining traction. Table 1 of this: [http://burawoy.berkeley.edu/PS/Introduction.Going%20Public,%20Going%20Global.pdf] covers a variety of kinds of sociology, most of which could have opponents. [[Special:Contributions/112.213.42.56|112.213.42.56]] 02:06, 12 June 2025 (UTC)

Hi, I think there's an alternative reading for this one in the last panel, the first time I read it as dismissing the student's question and continuing her statement, which is a quite common move in other comics and always implied with ....... This way, the research became a meta-critique of bad science and somewhat links to rigor vs curiosity. First time commenting here, idk what to do now. [[Special:Contributions/2A11:3:200:0:0:0:0:2004|2A11:3:200:0:0:0:0:2004]] 03:21, 12 June 2025 (UTC)?

Miss Lenhart has made the mistake common among many scientists of failing to include repeatability among her factors to be tested. Had she done so, ammonia would have disappeared from the results. [[Special:Contributions/82.13.184.33|82.13.184.33]] 08:28, 12 June 2025 (UTC)
:It's on the list, right below "adequate sample size" and "whether the lab has a lucky mascot" [[Special:Contributions/185.177.139.23|185.177.139.23]] 10:00, 12 June 2025 (UTC)

3035: Trimix

2025-01-09T13:05:35Z

Itub: {{cn}}

{{comic
| number = 3035
| date = January 8, 2025
| title = Trimix
| image = trimix_2x.png
| imagesize = 436x259px
| noexpand = true
| titletext = You don't want the nitrogen percentage to be too high or you run the risk of eutrophication.
}}

==Explanation==
{{incomplete|Created by a FLOATING TRIMIX SCUBA DIVER - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
{{w|Trimix (breathing gas)|Trimix}} is a gas used in {{w|SCUBA}} tanks that consists of {{w|helium}}, {{w|oxygen}}, and {{w|nitrogen}}. Trimix comes in some standard ratios between the component gases, depending on the required diving depth, for example 21/35/44 (percentage oxygen/helium/nitrogen), 18/45/37 and 15/55/30 for increasing depth. Helium safely substitutes a portion of the nitrogen to minimize nitrogen's narcotic effects at greater depths, and to ease the effort required for breathing, as merely reducing the nitrogen ratio in an oxygen/nitrogen mix will increase oxygen to levels that, at the pressures that exist at depth, {{w|Oxygen toxicity|creates other dangers}} (hence why the Trimix ratios also provide slightly lower proportions of oxygen). This comic suggests that, if the ratio of helium to nitrogen/oxygen is too high, a diver will float away before reaching the water to start a dive, as their tank of air starts behaving just like a sufficiently buoyant helium balloon. Divers rarely mix their own blends, so this would be the fault of the supplier who filled the tank from which the cylinder is filled. It would also be impossible to disproportionately breathe more of the non-helium, changing the ratio, although the way the comic depicts the tank only just starting to float ''might'' suggest that it is somehow being adjusted to the 'wrong' ratio as we watch.

The reason a helium balloon [[585: Outreach|creates lift]] is that it can inflate. The balloon has a thin and expandable layer, weighing almost nothing, that allows the intrinsically less dense gas to take up space at not much more than atmospheric pressure. The total weight of the filled balloon is less than the total weight of the air it displaces, thus creating {{w|buoyancy}}. A SCUBA tank is made of metal, is heavy and cannot inflate in anything like normal circumstances.{{cn}} Even with a {{w|vacuum balloon|perfect vacuum inside it}} (if that were possible) it would still weigh more than the equivalent volume of air. You would simply increase that weight if you pumped helium, or ''any'' kind of gas, into it. An inflating helium balloon also gets heavier, but this is more than compensated for by the greater increase in volume. The more you pumped into a rigid metal tank, the denser and heavier it would get, and it will never be able to create any degree of additional lift.

The real reason SCUBA divers need to be careful with the amount of helium is to not get too little (or too much) oxygen for the intended depth and pressure, as well as reducing the troublesome nitrogen.

The title text asserts that a trimix diver whose gas mix contains an excess of nitrogen runs "the risk of eutrophication". The term {{w|Eutrophication|eutrophication}} describes the process by which nutrients ("fertilizers") accumulate in an environment, typically a body of water, leading to consequences that are often unfortunate for inhabitants or users of that environment. The human body is an ecosystem, but one that is not typically subject to eutrophication, due to its manner of acquiring and jettisoning nutrients. Moreover, the nitrogen in trimix is diatomic elemental nitrogen, not the {{w|Nitrogen_fixation|"fixed"}} nitrogen that serves as a component of eutrophication. The diver would not breathe "fixed" nitrogen unless nitrogen-fixing bacteria were somehow incorporated into the SCUBA gear, a complex feature of dubious utility.

[[Randall]] addressed the question "how much helium is needed to lift a human body" in a [https://what-if.xkcd.com/62/ What if?] article. Helium has also featured in comics [[2766: Helium Reserve]] and [[2972: Helium Synthesis]].

==Transcript==
:[In a single frame five images of Cueball is shown as a kind of a cartoon event sequence, with each image a later time in the process. The first image to the left shows Cueball standing by the shore of a body of water. He is wearing SCUBA gear, goggles, breathing tubes, SCUBA tanks with a small H logo on it on his back, and swimming flippers, which almost touch the water.]

:[In the next four images he has the same equipment on, but with changes. It should be seen as he is still at the edge of the water, but that is not drawn in the next four depictions of Cueball.]

:[In the second image to the right of the first, Cueball's SCUBA tank is beginning to float upwards, so the end that is not teetered to Cueball move out and up, as shown with three small lines beneath the tank.]

:[In the third image the SCUBA tank is now floating above Cueball's head and the strings pull his arms a bit upwards. Cueball has turned his head looking up at the tank floating above and behind his head. Again three small lines beneath the tank indicates it is moving upwards.]

:[In the fourth image Cueball is now being lifted up, so his feet are now off the ground and he is tilting forward. The tank is now pointing it's bottom almost straight up and Cueball is looking down with his arms out the each side as the tank pulls him up. Two lines on either side of the tank indicate that it now wobbles above him as it lifts him up.]

:[In the fifth and last image the SCUBA tank is now pulling a dangling Cueball high above the ground, above his head's height in the first image. The tank is now turned so it points it's bottom to the left with lines on either side indicating wobbling motion. Cueball is floating as lying prone a bit bended on the middle as the tanks straps pulls him up. At this point he yells:]
:Cueball: ''Help!''

:[Caption below the panel:]
:Trimix SCUBA divers need to be careful not to let the helium percentage get too high.

{{comic discussion}}

[[Category:Comics featuring Cueball]]

3033: Origami Black Hole

2025-01-04T15:25:59Z

Itub: Add comparison with proton radius

{{comic
| number = 3033
| date = January 3, 2025
| title = Origami Black Hole
| image = origami_black_hole_2x.png
| imagesize = 272x480px
| noexpand = true
| titletext = You may notice the first half of these instructions are similar to the instructions for a working nuclear fusion device. After the first few dozen steps, be sure to press down firmly and fold quickly to overcome fusion pressure.
}}

==Explanation==
{{incomplete|Created by a PLANET-SIZED SWARM OF SELF-REPLICATING NUCLEAR POWERED PAPER COMPRESSION ROBOTS - Please change this comment when editing this page. It needs an explanation for the title text. Do NOT delete this tag too soon.}}

This comic shows what at first appears to be an actual page of {{w|origami}} directions, like [https://origami.me/crane/ this one] or [https://origami.guide/origami-animals/origami-rabbits/origami-sleeping-rabbit/ this one], except labeled "How to fold a real origami black hole". The "real" part may be referring to a "fake" origami black hole which would be a piece of origami made to look like a black hole (whatever that means). It seems black-hole-like origami does exist, as created by [https://parchmentandallthingspaper.wordpress.com/2011/11/16/folding/ Richard Sweeney]. The implication is that while the linked origami only resembles a black hole, Randall's instructions indicate a method to physically create a {{w|black hole}} out of origami paper. However, it quickly devolves into nothing other than repeating folds in half. This wouldn't really create a black hole unless one somehow additionally compressed the paper commensurate with its decrease in width and length as alluded to in the title text. Ordinarily it would become impossible long before the 190 folds in half that the instructions require. In fact - assuming a thickness of around 0.1mm the sum of the lengths and width of the paper would need to be around 10^110 meters for it to be possible to fold it 190 times.

The {{w|mathematics of paper folding}} were augmented with [https://web.archive.org/web/20051102085038/http://pomonahistorical.org/12times.htm work by a California high school student in 2001] who wrote equations that [https://web.archive.org/web/20211116013626/http://teachersofindia.org/sites/default/files/folding_paper_in_half.pdf related the size of paper to the maximum number of folds it could make], which has not yet exceeded the low teens in human competition. This could be exceeded by scoring the paper to cut and flatten the outer layers of the folds, but its thickness would immediately surpass its length, and compressing it beyond the size of its fibers would require some way to hold it together.

This comic is likely a reference to the {{w|Schwarzschild radius}} of a piece of paper. The Schwarzchild radius is a characteristic of every object that depends on the object's mass. If an object is compressed into the volume of a sphere with its characteristic Schwarzschild radius, then that object will become a black hole. (More specifically, it will become a {{w|Schwarzschild metric|Schwarzschild black hole}}.) As such, if a piece of paper were folded sufficiently many times so as to fit within its own Schwarzschild radius, it would become a black hole. However, this would require compressing the paper into a flat sheet at every step, otherwise the paper would have a thickness greatly exceeding its Schwarzschild radius.

If we assume standard {{w|origami paper#Kami|kami origami paper}} with a side length of 15cm and a weight of 70 grams per square meter, we get a Schwarzschild radius of 2.339×10^-30 meters corresponding to a mass of 1.575 grams. It follows that, ignoring the paper's thickness, we would need to halve each side length -log2((2×2.339×10-30)/0.15)=94.69 times to fit each side length within the "Schwarzschild diameter" of the paper. Using the square folding technique in the comic, this would take approximately 95*2=190 steps to complete, the exact number given in the comic.
Note that the radius of the resulting black hole is 15 orders of magnitude smaller than the {{w|https://en.wikipedia.org/wiki/Proton#Charge_radius|charge radius of a proton}}.

In actual fact, it's not possible to fold a piece of paper this many times, because the amount of paper 'wasted' in each fold [https://web.archive.org/web/20211116013626/http://teachersofindia.org/sites/default/files/folding_paper_in_half.pdf will quickly surpass the length and width of the paper]. For an ordinary letter-sized sheet (A4 or 8.5x11) the maximum number of folds is 7. The world record for the total number of folds is 12, done with a length of tissue paper 3/4 mile long. A group of MIT students demonstrated 13 folds using multiple miles of paper, but had to lay separate pieces together as it made them too thick to tape them. Materials other than paper, such as thin foil, can be folded more times. Not only that but, as the title text alludes to, prior to reaching any creation of a black hole, the pressures generated by the resulting {{w|Nuclear fusion#Confinement in thermonuclear fusion|fusion of its atoms}} must be overcome. Electron and neutron degeneracy pressure would also have to be overcome.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:How to fold a '''''real''''' origami black hole:

:Step 1.
:[A square sheet of paper shown folded in half, with a dashed line going across the middle, and an arrow pointing from one half to the other.]

:[In each step from Step 2. to Step 9., the paper is shown folded in half again and depicted in the same manner as Step 1. The aspect ratio of the sides alternates between 2:1 and 1:1.]
:Step 2.
:Step 3.
:Step 4.
:Step 5.
:Step 6.
:Step 7.
:Step 8.
:Step 9.

:Steps 10-189.
:[Text shown between tall square brackets:]
:Fold paper in half another 180 or so times.

:Step 190.
:[A labeled arrow points to a dot]
:Black hole!

{{comic discussion}}

[[Category:Physics]]

Talk:3033: Origami Black Hole

2025-01-04T15:22:50Z

Itub:

First post! [[User:RadiantRainwing|RadiantRainwing]] ([[User talk:RadiantRainwing|talk]]) 19:08, 3 January 2025 (UTC)
:[[First|…really? ''sigh'']] '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 02:27, 4 January 2025 (UTC)
::Sorry [[User:RadiantRainwing|RadiantRainwing]] ([[User talk:RadiantRainwing|talk]]) 03:55, 4 January 2025 (UTC)

All six gross attempts to follow these instructions have ended with the attemptor vanishing into themselves before reaching step 175.[[Special:Contributions/172.70.47.105|172.70.47.105]] 19:17, 3 January 2025 (UTC)

e[[Special:Contributions/162.158.10.131|162.158.10.131]] 20:14, 3 January 2025 (UTC)

Should we also add a mention of the /Mythbusters/ doing this? I don't remember the details or I would put it in. [[User:MAP|MAP]] ([[User talk:MAP|talk]]) 21:48, 3 January 2025 (UTC)

I started convincing chatgpt to tell me how to fold this origami at https://chatgpt.com/share/67785de4-9a4c-800e-80f5-31d12d999999 before running out of free credits. [[Special:Contributions/172.68.54.157|172.68.54.157]] 22:00, 3 January 2025 (UTC)

:Nice 404 error --[[Special:Contributions/162.158.90.211|162.158.90.211]] 04:25, 4 January 2025 (UTC)

Using rice paper you could easily reach 9 steps by pure hand pressure, although reaching fusion point -at or around 80 steps- would definitely require strong fingers indeed. Black holes clearly cannot exist, because they would require folding Chinese paper more than a red-blooded American can do, and this is not an option.{{unsigned ip|141.101.68.192|22:13, 3 January 2025}}

The current explanation that it's impossible to create a black hole by folding paper is only right in practical terms. If you manage to keep folding while keeping the same thickness the density of the paper will be far beyond that of a neutron star.--[[User:Pere prlpz|Pere prlpz]] ([[User talk:Pere prlpz|talk]]) 22:42, 3 January 2025 (UTC)

I would be impressed if you did manage to keep folding, since the goal size can be measured in Planck lengths with only six digits. Would you define it as a 'fold' after the entire thing fits inside an electron? (Tangentially, I'm not sure what theory suggests here - can a black hole exist at a scale which makes quantum tunnelling trivial?) {{unsigned ip|172.68.210.114|23:09, 3 January 2025}}
:I don't think we'll be able to answer that until we unify QM and GR. I don't think we currently have a theory that addresses quantum-sized black holes. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 23:23, 3 January 2025 (UTC)

This strip loosely follows a routine by Emo Philips in the 1980's where he describes tearing a piece of paper in half repeatedly until it explodes. He didn't give a count though. [[Special:Contributions/172.71.154.140|172.71.154.140]] 01:22, 4 January 2025 (UTC)

So, based on some quick math:
If we take the 10^110 meters of paper needed to complete this many folds, then you definitely can easily make a black hole. Generously assuming a 1mm wide strip, this gives us a folded stack of paper 1mm wide, 10^53 meters tall and long. 1 light year is 10^15 meters. So this piece of paper is now 10^38 light years long and wide. I.e. something like 10^27 universes tall and long.

Using the 70g per square meter number used above, you get 7^105 kg total mass. One solar mass is roughly 2^30 kg. Our paper weighs something like 10^54 times as much as the observable universe. This is very likely enough to reverse the expansion of the universe, and cause the entire observable universe to turn into a black hole. Or would it be a new big bang? I wonder what theoretical physics would say about a universe with 10^54 times as much mass / energy.

Also how exact does this comment system work? Is it easier if I just make an account?
-Nathan {{unsigned ip|172.68.22.223|08:19, 4 January 2025‎}}
:Only one rule I'm aware of - always sign your comments with ~ (tilde sign) repeated four times. If you aren't signed in this will timestamp with your IP address, if signed in it will show your username as follows: [[User:Alcatraz ii|Alcatraz ii]] ([[User talk:Alcatraz ii|talk]]) 10:09, 4 January 2025 (UTC)

I think the closest anyone got to the origami was this guy from Finland, who I felt deserves an honourable mention here. [https://www.youtube.com/watch?v=KuG_CeEZV6w Hydraulic Press Channel] [https://www.youtube.com/watch?v=MYBz7jjPzv8 Hydraulic Press Channel] "Closest" nevertheless still means a long way off. ;) [[User:PaulEberhardt|PaulEberhardt]] ([[User talk:PaulEberhardt|talk]]) 12:50, 4 January 2025 (UTC)

Alternate method: 1) get a large enough piece of paper; 2) wait for its gravitational collapse; 3) you have a black hole! This method is more convenient because the paper "folds" itself. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 15:22, 4 January 2025 (UTC)

3026: Linear Sort

2024-12-18T15:06:40Z

Itub: Let's assume that sleep() refers to the standard POSIX function, which takes a time in seconds. The same is true for sleep in several programming languages.

{{comic
| number = 3026
| date = December 18, 2024
| title = Linear Sort
| image = linear_sort_2x.png
| imagesize = 385x181px
| noexpand = true
| titletext = The best case is O(n), and the worst case is that someone checks why.
}}

==Explanation==
{{incomplete|Created in Θ(N) TIME by a recursive Bubble Sorter working on a multidimensional array - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
A common task in programming is to sort a list, a list being a collection of related elements of data that are stored in a linear fashion. There are dozens of algorithms that have been created through the years, from simple to complex, and each has its own merits with regards to how easy it is to understand / implement vs. how efficient it operates on the data.

The efficiency of an algorithm is measured in terms of O(), commonly referred to as "Big-O", which classifies the amount of time needed to execute the algorithm with respect to the size of the data. Specifically, the Big-O assignment describes the change in execution time when the size of the data set changes (typically, when it doubles). There are various measures of efficiency, such as:
<ul><li>O(1) - Constant, which means the execution time is independent of the size of the data</li>
<li>O(n) - Linear, which means the execution time varies in direct proportion to the size of the data</li>
<li>O(n log n) - "n log n", usually assigned to the fastest sorting algorithms</li>
<li>O(n2) - Quadratic", meaning the execution time is proportional to the square of the size of the data.</li></ul>
An algorithm that sorts data in Linear time would be a fantastic discovery, as the best general-purpose sorting methods are "n log n".

In computer science, the complexity of a problem can be described using {{w|Big O Notation}}. Operations generally take longer when they act on more elements (notated as "n"). A linear algorithm would be very simple: each element would take a short amount of time on its own, so the time it takes would be a multiple of the size of the list. For instance, if it takes one second to look at a picture, it would take ten seconds to look at ten pictures. So "look at a list of pictures" is a linear operation and would be described as having complexity O(n).

Sorting is more complex. The time it takes to sort a list of items grows quickly as you add more items to the list. The complexity of sorting algorithms generally ranges from O(n^2) to O(n*log n). For example, one way to sort is to look at all the values to find the first item, then look at all the values to find the second item, and so on until you've positioned every item in the right place. If "looking at a number" takes one second, then you could sort a list of 2 numbers in 4 seconds: look at both numbers, then look at them a second time. Sorting 3 numbers would take 9 seconds: look at all 3 numbers 3 times to find the right position. Sorting a deck of cards this way would take 52*52 seconds = about 45 minutes. You can probably read a card more quickly than that, but the point is that the amount of time it takes to sort a list grows faster the more items you are looking at. This is not the most efficient way to sort, but it gets the job done.

The 'linear' sort here uses the more efficient {{w|merge sort}}, which is linearithmic, taking O(n * log n) time. To give the illusion of taking linear time, it tries to make sure it takes 1e6 seconds per item in the list by sleeping for that length of time minus the time it actually took. This will appear to be linear time for up to very large values of n, since linearithmic time will take a huge value of n to exceed the time buffer given by the `sleep()`.

In other words, sorting 20 items will take 10 times as long as sorting 2 items, because after quickly sorting the two items, you just sit around wasting a huge amount of time until it is as slow as sorting a longer list.

The title text refers to the {{w|Best, worst and average case|best and worst case}} of the sort. The best, average and worst case of a merge sort is O(n log n), but this 'linear' sort is pretending that the best case is O(n). The title text then treats 'worst case' as the worst case for the creator of the algorithm (i.e. someone finds out that the sort isn't actually linear), rather than the worst case of the algorithm.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[The panel shows five lines of code:]
:function LinearSort(list):
::StartTime=Time()
::MergeSort(list)
::Sleep(1e6*length(list)-(Time()-StartTime))
::return

:[Caption below the panel:]
:How to sort a list in linear time

{{comic discussion}}

[[Category:Programming]]

Talk:3019: Advent Calendar Advent Calendar

2024-12-02T17:25:19Z

Itub:

Would this basically be triangle numbers? So on Christmas Eve you would open 300 windows?[[User:Tommyds|Tommyds]] ([[User talk:Tommyds|talk]]) 16:01, 2 December 2024 (UTC)

Yes and no. It's not 12 days of Christmas (as mentioned in the title text), so only the overall number of gifts are a triangle number; you open 30 windows on Christmas Day. The 12 days ref is key as the song generates more gifts if taken literally even in 12 days -- 78 on the last day, 66 on the previous day, etc, for a total of 364. [[User:Mneme|Mneme]] ([[User talk:Mneme|talk]]) 16:35, 2 December 2024 (UTC)

Notice that this year The Advent calendars are correct.
Normally, Advent calendars start at the 1st of December even if the Advent starts at a different day.
But this year the Advent also starts at the 1st of December. [[Special:Contributions/162.158.172.40|162.158.172.40]] 16:55, 2 December 2024 (UTC)

Donald Knuth wrote a paper for April 1984 Communications of the ACM that included an analysis of the complexity of 12 Days of Christmas. It's in the CACM archive https://dl.acm.org/doi/pdf/10.1145/358027.358042.

The explanation currently says "each day, he gets another advent calendar, which each contains 24-25 different items". I don't think that's correct; look at the picture: each day's calendar has one fewer item than the previous one. For example, the 24th only has 2 boxes and the 25th only has one. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 17:25, 2 December 2024 (UTC)

2982: Water Filtration

2024-09-07T12:12:58Z

Itub: Fix link for ionizing radiation sterilization

{{comic
| number = 2982
| date = September 6, 2024
| title = Water Filtration
| image = water_filtration_2x.png
| imagesize = 593x467px
| noexpand = true
| titletext = You'd think the most expensive part would be the quark-gluon plasma chamber, but it's actually usually the tube to the top of the atmosphere to carry the cosmic rays down.
}}

==Explanation==
{{incomplete|Created by WATER. JUST PLAIN WATER. NOTHING DONE TO IT, JUST PLAIN WATER. POSSIBLY DRINKABLE. - Do NOT delete this tag too soon.}}
This comic seems to be a diagram of how well water is purified, a common procedure done to make said water safe to drink. However, this well water is "purified" through a series of increasingly unnecessary, expensive, and possibly hazardous steps.

{| class="wikitable"
|-
!Step
!Real?
!Explanation
|-
|Water softener
|{{Yes|Real}}
|{{w|Water softening}} is the removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extends the lifetime of plumbing by reducing or eliminating scale build-up in pipes and fittings. The comic shows the water either being passed through some granulated material (presumably, {{w|ion-exchange resins}}) or into a precipitation chamber for lime (or soda ash) softening.
|-
|Reverse osmosis
|{{Yes|Real}}
|{{w|Reverse osmosis}} is a common step used in modern water-purification systems. It relies on using osmotic membranes and high pressures to separate water molecules from dissolved solutes and biological substances. Interestingly, it would also act as a softening step, rendering the previous step potentially redundant, depending on the goals for each step. It's also overkill for most wells, as groundwater often needs treatment targeted to only a couple contaminants, if any treatment at all.
|-
|Ultraviolet Sterilization
|{{Yes|Real}}
|{{w|Ultraviolet germicidal irradiation|Ultraviolet sterilization}} uses UV lamps at short wavelengths to kill micro-organisms in the water. In the USA, this is an unlikely method of well water sterilization, as the pathogens most likely to be found in well water (as opposed to surface water) are generally much more responsive to chemical disinfection. Many wells don't even need a disinfection step; whether this well needs disinfection or not, this is hardly the most impractical step in this treatment train.
|-
|Autoclave
|{{No|Fake}}
|{{w|Autoclaves}} are devices that sterilize items with high temperatures and pressures. While they are commonly used in hospital and laboratory settings to sterilize equipment, it is not normally used to purify water, as it would generate steam by the end of it. Furthermore, it would be extremely energy-intensive to convert the large volumes of water required for human consumption to steam. However, by the rest of this water purification setup, this much energy is barely anything in comparison.
|-
|Condenser
|{{No|Fake}}
|This isn't a purification step, but rather condenses the steam generated by the autoclave back into water.
|-
|Regular osmosis
|{{No|Fake}}
|Regular osmosis is the reverse of the previous Reverse Osmosis step. Oddly enough, this wouldn't directly contaminate the water, since the water is extremely pure as of this moment. Instead this step would simply remove water from the main stream, leaving the filtrate unchanged.
|-
|X-Ray Sterilization
|{{No|Fake}}
|While {{w|Sterilization_(microbiology)#Ionizing_radiation_sterilization|X-ray Sterilization}} is used to sterilize equipment, it is not normally used for water.
|-
|Carbon Filter
|{{No|Fake}}
|The water is passed through some volume of carbon. A riff on activated carbon filters, which are used in water filtration (seen later in the process).
|-
|Neutron Source
|{{No|Fake}}
|A {{w|neutron source}} generates high-energy neutrons. High-energy neutrons are highly penetrating and will cause ionization events to occur due to collision with atoms in the water. This can potentially make the water more radioactive due to the generation of radioactive isotopes.
|-
|Activated Carbon Filter
|{{Yes|Real}}
|{{w|Activated carbon}} is a form of carbon commonly used to filter contaminants from water and air, as it has a large surface area available to adsorb impurities on its surface. While this isn't a strange step to see in a water purification process, Randall makes a pun here with its proximity to the neutron source - the carbon has been '{{w|Neutron activation|activated}}' by the neutron source, and is currently radioactive. Water filtered through this may pick up radioactive isotopes from the filter.
|-
|Gamma Ray Sterilization
|{{No|Fake}}
|Similar to x-ray sterilization, this step uses {{w|https://en.wikipedia.org/wiki/Sterilization_(microbiology)#Ionizing_radiation_sterilization|gamma rays}} to sterilize the water. Gamma rays can potentially irradiate the water through photodisintegration if their energy is higher than the binding energy of oxygen.
|-
|Cosmic Ray Sterilization
|{{No|Fake}}
|Similar to the previous step, but this time using high energy {{w|cosmic rays}} to do so. This would be incredibly impractical, as cosmic rays are generally blocked by the atmosphere at high altitudes (as stated in the title text). Furthermore, their extremely high energy (shown to be in the exa-electron volt (10^18 eV) range) would cause multiple high-energy particles to be created on impact with the water molecules, irradiating the water significantly.
|-
|Electrolysis
|{{No|Fake}}
|The water is broken down into hydrogen and oxygen gas using an electric current. Assuming the gas outputs of this process are pure hydrogen and oxygen gas, this *would* be an extremely effective sterilization tactic, seeing as no known organism or water pollutant is entirely composed out of hydrogen or oxygen gas. Along with the next step, this step may be a misguided attempt to "take the water apart and clean each part individually". The hydrogen is sent to the ionizer, while the oxygen is sent to the oxygen spallation step.
|-
|Oxygen Spallation
|{{No|Fake}}
|The oxygen is apparently broken down back into hydrogen via a fictional form of {{w|Cosmic_ray_spallation|spallation}}. While spallation can form lighter nuclei from heavier ones, there is no known process to convert oxygen back down to hydrogen. It is unclear what happens to the neutrons present in the oxygen nuclei - whether they are removed, used to create hydrogen isotopes or allowed to decay into protons and electrons (the components of yet more hydrogen, when properly reintroduced). The hydrogen formed here is merged with the rest of the hydrogen before being sent to the ionizer.
|-
|Ionizer
|{{No|Fake}}
|The hydrogen output by the previous step is made into a plasma with free electrons and protons.
|-
|Quark-Gluon Plasma Chamber
|{{No|Fake}}
|The plasma outputted from the previous step is further energized into a {{w|Quark–gluon plasma}}, such as the one found just after the Big Bang. This follows the theme of the previous steps, which all serve to break the water down into their elementary components. The incredible energies involved in doing so are unachievable by current technologies (current particle accelerators can form such a plasma for very short periods of time and involve a very small amount of matter), and serve to highlight the impracticality of this setup (alluded to in the title text). The energies would also result in formation of lepton pairs from energy, which is presumably where the electrons from the previous step ended up.
|-
|Hydrogenation
|{{No|Fake}}
|This process converts the quark-gluon plasma outputted in the previous step into elemental hydrogen, reversing the previous two steps. Presumably, this is done via {{w|hadronization}} and {{w|recombination}}, however it is unclear how the {{w|baryon asymmetry}} needed to generate matter and not anti-matter is developed. In real life, {{w|hydrogenation}} is the process of adding hydrogen to unsaturated hydrocarbons. The resulting hydrogen is split into 2 streams leading into the Nucleosynthesis and Reverse Electrolysis steps.
|-
|Nucleosynthesis
|{{No|Fake}}
|Part of the hydrogen produced in the previous step is converted into oxygen via 2 sub-processes. The hydrogen is first converted into helium and carbon, through a combination of the {{w|proton-proton chain}} and the {{w|CNO cycle}} as per the labels on the step. This helium and carbon are then converted into oxygen through the {{w|alpha process}}. This step may also involve the {{w|triple-alpha process}}, seeing that the alpha process is typically only applicable to converting carbon into heavier elements, owing to the lack of a stable element with eight nucleons. These steps normally occur in the cores of massive stars. It is not known how the oxygen is filtered from the extremely hot plasma of fusion products.
|-
|Reverse Electrolysis
|{{No|Fake}}
|This step is essentially a fuel cell, utilizing an electrochemical reaction to convert hydrogen and oxygen back into water and electricity.
|-
|Adding Well Water
|{{Yes|Real}}
|A second pipe is linked to the first that simply feeds untreated well water into the pipes, partially undoing the entire process. Even if the well water is only a small portion of the faucet water, its presence has now made the now incredibly pure water impure. This act of putting well water into the faucet after treating it may be a riff on the cultural interest in "spring water" or "pure glacial water" that is said to have additional minerals or beneficial properties but is oftentimes not meaningfully distinct from properly treated tap water.

Alternatively, it may be that the level of purity achieved by this setup is so overkill, and the cost per liter processed so high, that it's simply more efficient to treat just enough of the water to dilute the rest of the water to acceptable levels of contaminants. For example, it's common to use a partial bypass to supply water to the shower, since shower water does not need to be potable. Also, some well water systems are clean enough to not need any treatment at all and can be used straight from the well, and some water systems are only slightly high in a single chemical contaminant that can be addressed by blending the water, either with treated water or another source (treated or untreated). Perhaps the treatment process led to enough radioactivity that blending with the original source was required to address radioligical contamination (either gross alpha radiation or specific radionuclides).
|}

The title text briefly covers the cost implications of the components. Various 'real' filter elements will either have material or energy costs (if not both), in operation or to replenish their effectiveness, and the high energy input needed to disassociate hadrons into raw quark–gluon plasma (at bulk levels) would seem to require the most in terms of running the equipment. But it is pointed out that to ''ensure'' enough cosmic rays reach that particular phase of sterilization, there would have to be a pipe (not shown) leading out to the edge of the atmosphere to optimistically carry down such particles (due to also containing ''no'' air, i.e. keeping it out to negate the normal {{w|Air shower (physics)|shielding and dissipating effect}} of the atmosphere).

Whether a one-off-cost or needing regular replacement, the setting up of such a tubular structure (a vertical air-proof pipe perhaps somewhere between 100 and 10,000 kilometres high) would be technically challenging and has not ever been actually accomplished. The conditions for a quark–gluon plasma, albeit in limited quantities, at least have been fulfilled at {{w|CERN}} (with its 27 kilometer airless pipe that goes round within a vast circular tunnel).

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

{{comic discussion}}

Talk:2968: University Age

2024-08-06T11:51:41Z

Itub: typo

[[1477]] anyone? [[Special:Contributions/162.158.41.131|162.158.41.131]] 03:29, 6 August 2024 (UTC)
:Not relevant in my opinion. In [[1477: Star Wars]] Cueball is surprised by how fast time seems to flow past him. Not surprised that everything ages at the same rate as the Cueball in this comic. There are more than 40 comics relating to [[:Category:Time|time]] on explain xkcd...

Was there a USA political debate this week that I didn't hear about? About. Hear of it's existence. I Assuredly didn't hear it. [[Special:Contributions/172.70.175.121|172.70.175.121]] 06:27, 6 August 2024 (UTC)

On a related note, today I set a new personal best for time spent continuously being alive. I'm still well behind the world records, but I have beaten pretty much all of the current collegeate athletes. [[User:RegularSizedGuy|RegularSizedGuy]] ([[User talk:RegularSizedGuy|talk]]) 07:08, 6 August 2024 (UTC)

"'''Unfortunately, I have terrible news'''" kind of feels to me like — almost — there is a pop culture reference here that I am missing (I'd say I feel 33% of the way towards that feeling; certainly somewhere less likely than even). It just seems like a little too strong of a statement to be what President Cueball would say in the moment. That said, I can't find any support for such a half-baked theory. Although there is an "I have terrible news" (without "Unfortunately") from [https://www.imdb.com/title/tt2572734/characters/nm0278979 The Office, Season 9, "Vandalism"] ([https://www.youtube.com/watch?v=Eo8RzH-6Tfw&t=614s video]), but it doesn't strike me as particularly significant. 
¶ Apart from that, I sort of expected more emphasis on obscure schemes, like (a) increasing the average altitude of the rival university to increase its velocity for the tiny relativistic effect, e.g. by funding construction of an observatory for its astronomy department; (b) attempting to measure the founding dates more precisely, e.g. what if it were only 1-year-183-days older; (c) merger with the rival, ala the proposed MIT/Harvard mergers of the early 20th century; &c. [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 09:51, 6 August 2024 (UTC)

: I thought the terrible new was that, after sending the rival university on a round trip at relativistic speed, due to an unfortuneate miscalculation, the rival university would collide with Earth while still going too fast, causing the destruction of the planet. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:51, 6 August 2024 (UTC)

Talk:2968: University Age

2024-08-06T11:51:13Z

Itub:

[[1477]] anyone? [[Special:Contributions/162.158.41.131|162.158.41.131]] 03:29, 6 August 2024 (UTC)
:Not relevant in my opinion. In [[1477: Star Wars]] Cueball is surprised by how fast time seems to flow past him. Not surprised that everything ages at the same rate as the Cueball in this comic. There are more than 40 comics relating to [[:Category:Time|time]] on explain xkcd...

Was there a USA political debate this week that I didn't hear about? About. Hear of it's existence. I Assuredly didn't hear it. [[Special:Contributions/172.70.175.121|172.70.175.121]] 06:27, 6 August 2024 (UTC)

On a related note, today I set a new personal best for time spent continuously being alive. I'm still well behind the world records, but I have beaten pretty much all of the current collegeate athletes. [[User:RegularSizedGuy|RegularSizedGuy]] ([[User talk:RegularSizedGuy|talk]]) 07:08, 6 August 2024 (UTC)

"'''Unfortunately, I have terrible news'''" kind of feels to me like — almost — there is a pop culture reference here that I am missing (I'd say I feel 33% of the way towards that feeling; certainly somewhere less likely than even). It just seems like a little too strong of a statement to be what President Cueball would say in the moment. That said, I can't find any support for such a half-baked theory. Although there is an "I have terrible news" (without "Unfortunately") from [https://www.imdb.com/title/tt2572734/characters/nm0278979 The Office, Season 9, "Vandalism"] ([https://www.youtube.com/watch?v=Eo8RzH-6Tfw&t=614s video]), but it doesn't strike me as particularly significant. 
¶ Apart from that, I sort of expected more emphasis on obscure schemes, like (a) increasing the average altitude of the rival university to increase its velocity for the tiny relativistic effect, e.g. by funding construction of an observatory for its astronomy department; (b) attempting to measure the founding dates more precisely, e.g. what if it were only 1-year-183-days older; (c) merger with the rival, ala the proposed MIT/Harvard mergers of the early 20th century; &c. [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 09:51, 6 August 2024 (UTC)

: I thought the terrible new was that, after sending the rival university on a round trip at relativistic speed, due to an unfortuneate miscalculation, the rival university would collide with Earth while still going to fast, causing the destruction of the planet. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:51, 6 August 2024 (UTC)

Talk:2842: Inspiraling Roundabout

2023-10-17T11:33:02Z

Itub:

First edit. I'm unfamiliar with the road rules in the comic so I just added the transcript in it's most basic form. [[User:OmniDoom|OmniDoom]] ([[User talk:OmniDoom|talk]]) 02:00, 17 October 2023 (UTC)
:don't worry, even a wrong explanation is better than no explanation because it tricks people into being correct for you [[User:Certified_nqh|Me]][[[285: Wikipedian Protester|''citation needed'']]][[Category:Pages using the "citation needed" template]] 03:15, 17 October 2023 (UTC)

added longer explanation [[User:Certified_nqh|Me]][[[285: Wikipedian Protester|''citation needed'']]][[Category:Pages using the "citation needed" template]] 03:05, 17 October 2023 (UTC)

Could we create a category for these "traffic" or "driving" related comics? This would include this comic and the previous, and others that relate to driving/cars/traffic. [[Special:Contributions/172.70.211.37|172.70.211.37]] 04:02, 17 October 2023 (UTC)

in left lane driving countries this would work pretty well as a roundabout

I've heard the Spanish and British road authorities are planing to implement this for roads going to France. [[Special:Contributions/172.64.236.144|172.64.236.144]] 06:39, 17 October 2023 (UTC)

Actually, the correct solution is an out-spiraling roundabout, which if properly designed means that if you start in the correct lane, you end up at the correct exit without changing lanes. [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 07:37, 17 October 2023 (UTC)

Well if it spiralled the other way it would be a great roundabout design.[[Special:Contributions/162.158.203.28|162.158.203.28]] 08:14, 17 October 2023 (UTC)

Out-spiraling roundabouts are getting more popular in the UK - they recently repainted the Wandsworth Bridge Roundabout as an out-spiral, and it's gone from one being one of the worst roundabouts in the area to one of the best. [[Special:Contributions/172.70.90.153|172.70.90.153]] 10:04, 17 October 2023 (UTC)

About driving in circles for hours: https://www.youtube.com/watch?v=iAgX6qlJEMc --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:32, 17 October 2023 (UTC)

== Magic Roundabouts ==

See these two "unusual" roundabouts in England

https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempstead)

https://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

Actually, they are (no longer) roundabouts, but Ring Junctions. Effectively mini Ring Roads. [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 07:37, 17 October 2023 (UTC)

In France at least this design would not create any conundrum because roundabout rules are clearly stated and independent of ground markings. It could still be somewhat confusing.

Talk:2842: Inspiraling Roundabout

2023-10-17T11:32:12Z

Itub:

First edit. I'm unfamiliar with the road rules in the comic so I just added the transcript in it's most basic form. [[User:OmniDoom|OmniDoom]] ([[User talk:OmniDoom|talk]]) 02:00, 17 October 2023 (UTC)
:don't worry, even a wrong explanation is better than no explanation because it tricks people into being correct for you [[User:Certified_nqh|Me]][[[285: Wikipedian Protester|''citation needed'']]][[Category:Pages using the "citation needed" template]] 03:15, 17 October 2023 (UTC)

added longer explanation [[User:Certified_nqh|Me]][[[285: Wikipedian Protester|''citation needed'']]][[Category:Pages using the "citation needed" template]] 03:05, 17 October 2023 (UTC)

Could we create a category for these "traffic" or "driving" related comics? This would include this comic and the previous, and others that relate to driving/cars/traffic. [[Special:Contributions/172.70.211.37|172.70.211.37]] 04:02, 17 October 2023 (UTC)

in left lane driving countries this would work pretty well as a roundabout

I've heard the Spanish and British road authorities are planing to implement this for roads going to France. [[Special:Contributions/172.64.236.144|172.64.236.144]] 06:39, 17 October 2023 (UTC)

Actually, the correct solution is an out-spiraling roundabout, which if properly designed means that if you start in the correct lane, you end up at the correct exit without changing lanes. [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 07:37, 17 October 2023 (UTC)

Well if it spiralled the other way it would be a great roundabout design.[[Special:Contributions/162.158.203.28|162.158.203.28]] 08:14, 17 October 2023 (UTC)

About driving in circles for hours: https://www.youtube.com/watch?v=iAgX6qlJEMc --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:32, 17 October 2023 (UTC)

Out-spiraling roundabouts are getting more popular in the UK - they recently repainted the Wandsworth Bridge Roundabout as an out-spiral, and it's gone from one being one of the worst roundabouts in the area to one of the best. [[Special:Contributions/172.70.90.153|172.70.90.153]] 10:04, 17 October 2023 (UTC)

== Magic Roundabouts ==

See these two "unusual" roundabouts in England

https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempstead)

https://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

Actually, they are (no longer) roundabouts, but Ring Junctions. Effectively mini Ring Roads. [[User:RIIW - Ponder it|RIIW - Ponder it]] ([[User talk:RIIW - Ponder it|talk]]) 07:37, 17 October 2023 (UTC)

In France at least this design would not create any conundrum because roundabout rules are clearly stated and independent of ground markings. It could still be somewhat confusing.

Talk:2794: Alphabet Notes

2023-06-27T11:28:12Z

Itub:

No, we must rid ourselves of the redundant C. Also we need to bring back Ð and Þ. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 19:20, 26 June 2023 (UTC)
:I agree with your second point, but not your first (This is why: https://www.youtube.com/watch?v=chpT0TzietQ) [[explain_xkcd:Community_portal/Miscellaneous#Help_with_Creating_a_User_Page|Trogdor147]] ([[explain_xkcd:Community_portal/Miscellaneous#Help_with_Creating_a_User_Page|talk]]) 01:04, 27 June 2023 (UTC)

daMNation, randoMNess, chiMNey, gyMNastics, autuMN are not fancy words [[Special:Contributions/172.70.250.204|172.70.250.204]] 19:43, 26 June 2023 (UTC)

You can't have rUIn without U and I together!

Or UI! [[User:GetPunnedOn|GetPunnedOn]] ([[User talk:GetPunnedOn|talk]]) 22:35, 26 June 2023 (UTC) (Reply to above text)

We need to bring back way more letters: https://youtu.be/wJxKyh9e5_A
--[[Special:Contributions/172.71.246.84|172.71.246.84]] 20:33, 26 June 2023 (UTC)

I would be useful to include the letter frequency table from Wikipedia at https://en.wikipedia.org/wiki/Letter_frequency but we don't appear to have the "bartable" template from wikipedia to display bar charts. It would explain a lot about the haunted letters in particular to have it.

The circled JK is clearly referencing the text-language abbreviation for "just kidding", and the bracketed VW... I'm not sure but, it might have to do with Volkswagen, or the spikiness of the letters, or "why isn't W called double-V or at least next to the U".
[[Special:Contributions/172.70.174.166|172.70.174.166]] 21:18, 26 June 2023 (UTC)

:I think the bracketed V and W is referencing the fact that W is equivalent to two V’s together. (Or the fact that W originated as VV) —[[User:Purah126|Purah126]] ([[User talk:Purah126|talk]]) 23:39, 26 June 2023 (UTC)
: Huh, I always thought "jk" was for "joke". Luckily it doesn't change its meaning... (unlike the person who thought "LOL" was for "Lots of Love" https://www.quora.com/Does-LOL-stand-for-Love-you-loads-or-Lots-of-love ) [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 07:19, 27 June 2023 (UTC)

:In some languages, such as French, w is called "double v" (or its literal transaltion), which makes more sense. :-) --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 11:28, 27 June 2023 (UTC)

Added the Twinkle Twinkle justification into the existing explanation. But I might be talking out of my hat, as I'm British and only really know the US treatment from imported media. (Sesame Street? No, I can only bring to mind their counting 1-12 song. And "Conjunction Junction".) The UK's "alphabet" recital form, at least when I was that young, is far less musical. And tends to rhyme "Z" with "Drop dead!", naturally. ;) [[Special:Contributions/172.70.90.183|172.70.90.183]] 22:06, 26 June 2023 (UTC)

Pretty sure he isn't questioning the position of Q as much as its inclusion. If we wanted to reform English spelling, we could get rid of Q pretty kwiklee.[[Special:Contributions/172.71.26.207|172.71.26.207]] 23:29, 26 June 2023 (UTC)

: Or maybe it's that old joke about why U doesn't follow Q in the alphabet? [[Special:Contributions/141.101.98.107|141.101.98.107]] 10:09, 27 June 2023 (UTC) Artinum

I can't be the only one who thinks there's a dirty joke in the line '"D" is solid, at least' [[Special:Contributions/172.71.150.140|172.71.150.140]] 00:18, 27 June 2023 (UTC)
:I didn't. I think that joke is simply that D is a simple, enclosed shape. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:27, 27 June 2023 (UTC)
:B is also a simple, enclosed shape. I thought that the 'no heavy hitters' comment might be a reference to 'ETAION SHRDLU', the 12 most common letters in written English arranged in descending order of frequency - since it contains neither B nor C (nor, indeed, F or G).[[Special:Contributions/172.69.79.146|172.69.79.146]] 05:12, 27 June 2023 (UTC)

Talk:2676: Historical Dates

2022-09-26T12:53:54Z

Itub:

Source for the Excel/Lotus 123 relation with Dec 30th, 1899: https://social.msdn.microsoft.com/Forums/office/en-US/f1eef5fe-ef5e-4ab6-9d92-0998d3fa6e14/what-is-story-behind-december-30-1899-as-base-date?forum=accessdev
[[User:Victor|Victor]] ([[User talk:Victor|talk]]) 08:14, 24 September 2022 (UTC)

I feel this one. My birthday happens to be within 24 hours of [[1179: ISO 8601|1970-01-01]], so I keep getting caught off guard for a moment whenever I see my birthday showing up in one of these contexts. -- [[User:KarMann|KarMann]] ([[User talk:KarMann|talk]]) 08:35, 24 September 2022 (UTC)

We're going to need the date stamp format for 1890 ticker tape for this one. Anyone? [[Special:Contributions/172.70.214.183|172.70.214.183]] 11:59, 24 September 2022 (UTC)
:MM/DD/YY, with leading zeros omitted, and no I don't know why, but I suggest Google Books Ngrams might have a clue as to when that abomination started. [[Special:Contributions/172.69.22.61|172.69.22.61]] 12:03, 24 September 2022 (UTC)
::Not necessarily with pairs of the slash '/' _ . . _ . but also hyphens '-' _ . . . . _ and periods '.' . _ . _ . _ were used as delimiters in MM?DD?YY, which if I remember right dates to the 1500s when accounting ledgers were invented. [[Special:Contributions/172.70.207.8|172.70.207.8]] 12:10, 24 September 2022 (UTC)
::::Are you with the NSA and have a data warehouse of all the ticker tapes ever sent or something? [[Special:Contributions/162.158.166.185|162.158.166.185]] 12:45, 24 September 2022 (UTC)
:::::No, but my great grandparents thought ticker tape parades were littering, because Great Grandma worked in an office and Great Grandpa worked for sanitation, so we have a bunch of boxes in the attic filled with what she was supposed to throw out her window. [[Special:Contributions/172.71.158.75|172.71.158.75]] 12:54, 24 September 2022 (UTC)
:::That would be [https://www.jstor.org/stable/40697544 1299]. But I'm not sure how this is going to help us explain the comic, unless you perhaps are suggesting we enumerate date representation clusters somehow? [[Special:Contributions/172.69.22.61|172.69.22.61]] 12:32, 24 September 2022 (UTC)
:::: Someone should ask GPT-3 for a list of the top ten dates. [[Special:Contributions/172.69.22.71|172.69.22.71]] 12:59, 24 September 2022 (UTC)

Just putting January 2, 2006 here: https://stackoverflow.com/questions/20530327/origin-of-mon-jan-2-150405-mst-2006-in-golang [[Special:Contributions/172.69.22.161|172.69.22.161]] 12:28, 24 September 2022 (UTC)

Do we need a comment about how Pope Gregory XIII obliterated October 5th through 14th, 1582? [[Special:Contributions/172.71.158.25|172.71.158.25]] 13:30, 24 September 2022 (UTC)

In Unix, January 1st, 1970 0h0 is 0. In Excel, December 31st, 1899 is 1. Either Randal forgot December has 31 days (hence December 30th) or he though Excel starts to count at 0 like Unix. For more information in the (probably) intentional bug in Excel https://www.joelonsoftware.com/2006/06/16/my-first-billg-review/ .

In Excel, January 1, 1900 is 1. However, December 30, 1899 is the "epoch" date that you should use if you want to convert a current date (anything on or after March 1, 1900) to a number by "subtracting" the current date minus the epoch date (counting the number of days since the epoch date). The reason it isn't December 31 is because of the above mentioned bug where Excel counts February 29, 1900 as a day even though it actually isn't.
::I just checked it in different versions of Excel, you are right. Meanwhile LO Calc it is Dec 31th 1899... I'll try to edit the explaination to make it more universal. [[User:Asterisk|Asterisk]] ([[User talk:Asterisk|talk]]) 21:11, 24 September 2022 (UTC)
:::In Excel 2002 (XP) it actually interprets it as "1900-01-00" or "January 0, 1900", that's weird [[User:Asterisk|Asterisk]] ([[User talk:Asterisk|talk]]) 21:25, 24 September 2022 (UTC)

Speaking of dates, shouldn’t this one be in the category “Saturday comics”? Or was it still Friday in Hawaii when it came out? [[Special:Contributions/162.158.107.246|162.158.107.246]] 17:57, 24 September 2022 (UTC)
:While uploaded by the bot on 2022-09-24, the xkcd archive (and json data) states that this comic was published on 2022-09-23 —[[User:Theusaf|theusaf]] ([[User talk:Theusaf|talk]]) 18:44, 24 September 2022 (UTC)
::The same thing happened on Monday. The comic didn't show up until Tuesday, but it was still dated Monday. Someone suggested that the book tour has been interfering with Randall's schedule. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 21:25, 24 September 2022 (UTC)

I don't understand what the White Lotus Religion has to do with the comment in the title text. Nothing in the Wikipedia article linked mentions 1899 or December 30 in connection with that religion. --[[Special:Contributions/172.70.100.158|172.70.100.158]] 01:03, 25 September 2022 (UTC)
:Yeah, I believe The White Lotus reference is a stretch, but it is possible, just based on the name "Lotus". This would have to be confirmed by Randall Munroe. On another matter; I'm sorry I don't have citations for Unix only becoming complete in mid-March. Dennis Ritchie himself wrote of it's birthing in 1969 in the 1978 paper,"The Evolution of the Unix Time-sharing System*" I'm quite sure of the Unix timestamp being a kind of "hack" used until a calendar app could be created. PS This Jan 1, 1970 problem was even in the first iPhones, which could be bricked by setting the date to Dec 31, 1969 or any date previous. Many an Apple Store had to put up with this nuisance.{{unsigned|Cuvtixo|04:35, 25 September 2022}}
::For a number of reasons, I thought it best to revert your addition, rather than vastly edit it to make it generally better (had some good intent behind it, don't get me wrong). I thought maybe you might want to try again rather than be mercilessly re-edited into saying something you didn't mean. Didn't see your comment down here until after, though, or I might have put my energy into just prompting you to do the changes already. (I can't create a Talk page for you, in my IP state, or I might have buzzed you upon that instead.) [[Special:Contributions/172.71.178.207|172.71.178.207]] 11:47, 25 September 2022 (UTC)

It is truly astonishing how many records there are of financial transactions between around 60 CE and 99 CE. We also found some 30-year mortgages created in 70 CE whose final payment was due in "00", an early Y0K bug (there was no year 0). [[Special:Contributions/172.70.38.143|172.70.38.143]] 13:59, 25 September 2022 (UTC)
:There is also indisputable evidence of a previously unrecorded major recession in the late first century, evidenced by the steady reduction in the number of records throught the 90's. [[Special:Contributions/172.70.34.213|172.70.34.213]] 14:29, 25 September 2022 (UTC)

Related topic: a lot of Scottish Whisky distilleries were "founded" in the 1830s, although they existed (long) before that. But a change in taxation laws made it easy to become a legal distillery.

;Overdue What-If (blog article) notification.
I just added a new row to (one of the pages for) [[what_if#Articles|What-If? articles]]. Seen last week, thought someone else would have noticed it. Turns out to have ready been published a couple of weeks earlier, so jumped right in anyway. And, as per instructions, notifying on the "latest comic page". Note the complete lack of thumbnails in that list, since (with apparently broken links) around the Interplanetary Cessna article. Which is yonks ago. And I can't really correct that issue, so leaving it as a project for someone else to do, as with any other listing-pages. ...but that's all administratium, on top of the basic FYI that I'm trying to convey here. [[Special:Contributions/172.70.86.8|172.70.86.8]] 01:22, 26 September 2022 (UTC)

My first thoughts when reading this comic was that 30 Dec 1899 was the last business day of the 19th century, and that thousands (or millions) of people were selling their worldy assets, in the mistaken belief that the world would come to an end (sort of like a Y2K scare, but without the tech). [[User:Beechmere|Beechmere]] ([[User talk:Beechmere|talk]]) 03:29, 26 September 2022 (UTC)Beechmere

I don't suppose a zero Julian date [January 1, 4713 BC] is very likely to appear except in astronomy data?
[[Special:Contributions/172.70.174.159|172.70.174.159]] 09:08, 26 September 2022 (UTC)

Does anyone here have access to GPT-3 at https://beta.openai.com/playground ? Everyone should; I used to but used up the maximum submissions to it. I think asking it for a list of the most common dates as suggested above is a great idea. [[Special:Contributions/172.69.22.123|172.69.22.123]] 12:52, 26 September 2022 (UTC)

Maybe there should be another spike on January 1st, 1980. With PCs in the 1980s, before having a battery to power the BIOS and clock became a standard feature, every time you turned on the computer you had to enter the system date and time. It defaulted to 1/1/1980, and it was very easy just to hit enter and keep the default. Which most people I knew did. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 12:53, 26 September 2022 (UTC)

Talk:2375: Worst Ladder

2020-10-22T13:24:49Z

Itub:

Their ladder is obviously placed somewhere where they all have to walk under it to get into the boardroom. [[Special:Contributions/162.158.158.247|162.158.158.247]] 00:59, 22 October 2020 (UTC)

I find it extremely pleasing that within 20 minutes the XKCD itself in on the front page of Google results [[Special:Contributions/108.162.237.4|108.162.237.4]] 01:09, 22 October 2020 (UTC)

Google searches gonna be skyrocketing for "Worst Ladder". --01:24, 22 October 2020‎ (UTC) 198.41.238.108 (Please sign your comments)
:Can definitely see when the comic was posted [https://trends.google.com/trends/explore?date=now%201-d&q=worst%20ladder]. Maybe we should add a screenshot to the trivia section --[[User:Luckykaa|Luckykaa]] ([[User talk:Luckykaa|talk]]) 07:16, 22 October 2020 (UTC)

Can someone create a category for "business"-related comics? There are quite a few (some related to Beret Guy's businesses, but others just general). [[Special:Contributions/172.69.33.37|172.69.33.37]] 01:31, 22 October 2020 (UTC)

Can someone confirm if this comic is related to Quibi's shutdown announcement? Because if it isn't, then it's one major coincidence. [[User:Aderon|Aderon]] ([[User talk:Aderon|talk]]) 01:50, 22 October 2020 (UTC)
:I'm not entirely sure of the parallels but I'd love them to be in the article--[[User:FrankHightower|FrankHightower]] ([[User talk:FrankHightower|talk]]) 02:07, 22 October 2020 (UTC)

I thought someone had added a practical screenshot of Google's "worst ladder" search, before realising it was one of the inline Google-powered ads, this one 'aptly' for a certain popular online auction site which illustrated various ladders apparently up for sale upon its platform.... [[Special:Contributions/141.101.107.82|141.101.107.82]] 01:55, 22 October 2020 (UTC)
:I tried doing it, but it says I'm not allowed--[[User:FrankHightower|FrankHightower]] ([[User talk:FrankHightower|talk]]) 02:07, 22 October 2020 (UTC)
:: I saw that link (yours?) too, and appreciated it. Now, being just an IP I'm fairly sure I'd not be allowed to upload media to the Explain wiki, but I know it's been possible for others. Like with created highlights of the XKCD Garden, IIRC. But maybe it isn't automatic to all usernames but time/authorisation-prompted, after a certain length of engagement. Maybe the answer lies in the Community Portal, or the question could be asked there if not. [[Special:Contributions/162.158.158.225|162.158.158.225]] 02:46, 22 October 2020 (UTC)

I've got a screenshot of "Worst Ladder" GIS results taken around 02:45 UTC. Would it be worth adding to the wiki, and is there a way to upload it here? [[User:GreatWyrmGold|GreatWyrmGold]] ([[User talk:GreatWyrmGold|talk]]) 02:49, 22 October 2020 (UTC)

I kept feeling like I was missing some more specific reference about what company could possibly find itself replaced by "worst ladder" searches. Like, it's so specific it doesn't feel like "welp, all media companies are SOL because everyone just likes ladders now", it feels like this company was somehow in a niche that was uniquely affected...but I can't imagine what that niche could be haha.[[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 03:31, 22 October 2020 (UTC)
:No, I think "worst ladder" is just a stand-in for any random (and absurd) internet hype. I mean, who would ever be interested in watching people randomly pouring buckets of ice water over their heads... [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 06:56, 22 October 2020 (UTC)

I moved the Google Image Search part to the Trivia section. The actual results of such a searhc are imho not relevant for explaining the comic. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 08:14, 22 October 2020 (UTC)

Also try "worst wheelchair ramps." [[User:Probably not Douglas Hofstadter|Probably not Douglas Hofstadter]] ([[User talk:Probably not Douglas Hofstadter|talk]]) 12:34, 22 October 2020 (UTC)

I thought the reason for the disastrous Home Depot tie-in was the lawsuits that resulted from people buying Worst Ladders (tm) and having accidents. --[[User:Itub|Itub]] ([[User talk:Itub|talk]]) 13:24, 22 October 2020 (UTC)