explain xkcd - User contributions [en]

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2026-01-14T20:34:08Z

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2026-01-14T20:33:56Z

Lemondoge: Add __HIDDENCAT__

Oh dear... Hard to explain or discuss symbols without being able to display them.

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Category:Pages with broken file links

2026-01-14T20:33:48Z

Lemondoge: Add __HIDDENCAT__

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2026-01-14T20:33:33Z

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These are the pages in where the page size is bigger than the maximum allowed template size.

[[Category:Problematic pages]]
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1376: Jump

2024-05-10T00:15:21Z

Lemondoge: There's a space between "land" and the ellipsis in the original title text

{{comic
| number = 1376
| date = June 2, 2014
| title = Jump
| image = jump.png
| titletext = Or that I'm at least following the curve of the Earth around to land ...
}}

==Explanation==
[[Cueball]] is presumably experiencing a common dream subject, flying or floating. As in [http://boards.straightdope.com/sdmb/showthread.php?t=382657 many varieties of such a dream], the ability to fly, float or glide only gradually manifests, going from longer and longer jumps to a sort of flight or hovering. In Cueball's case, his jumps become longer and 'lighter' until at last he is gliding just above the surface of the Earth. He has apparently had such a dream before, with just such a flight mechanic manifesting itself, as he indicates that he 'loves' these dreams.

In his presumed dream, Cueball finally achieves his gliding flight just as he reaches the shoreline, and his gliding carries him over the water's edge and out to sea. After a moment's reflection, he realizes that if he were really gliding out to sea without any real apparent means of control, his situation would presumably be rather perilous — death by starvation or thirst, gradually slowing down and becoming 'stuck' over the water with no way to land, the loss of his gliding ability as suddenly as it came, etc., all suggest themselves as possible perils he would now be subject to if, in fact, his 'dream' were actual reality. Thus he eventually indicates that he ''hopes'' it is a dream, in contrast to his feeling at the comic's opening.

The title text adds a further worry not immediately apparent unless one considers the possibility that Cueball's 'gliding' will continue in a straight line in relation to the Earth's surface. In that case he would continue moving straight while the Earth's surface would curve away beneath him, sending him out into space instead of the relatively preferable scenario of merely floating across the ocean to the opposite shore. After all, if the laws of physics had changed to permit hovering/flying, consequences would be unpredictable — i.e. there'd be no assurance one would maintain a constant hovering height rather than take leave of the planet as one flies forth. One thing about miracles is that all bets are off!

Also note that this situation is similar to the case of {{W|Newton's cannonball}}. However, that is actually in very-low-earth-orbit — and you would need to be going 7,300 m/s, or about 16,000 mph (26,000 km/h) to stay in orbit. At that speed, of course, air friction would quickly destroy the cannonball or person. This is clearly not the case in the dream.

Getting weightless and drifting around was a fantasy in [[226: Swingset]]. The comic [[417: The Man Who Fell Sideways]] has some resemblance to this one. In [[942: Juggling]], Cueball throws some balls and later a book. They [http://hitchhikers.wikia.com/wiki/Flying miss the ground].

In the book ''[[Thing Explainer]]'' Cueball jumps to score with a basketball in the explanation for ''Playing Fields'' only to find that he keeps rising steadily along a straight curve up above the hoop. Very similar to this jump that just lets Cueball float straight afterwards.

==Transcript==
:[In the first panel Cueball is seen as a stop motion cartoon (12 drawings of the same Cueball) as he is jumping down a small hill — jumping longer and longer between sentences. Jump is written over the head of Cueball that perform the jump until he floats.]
:Cueball: I love these dreams
:''Jump''
:Cueball: Each jump is a little longer
:''Jump''
:Cueball: Each push off the ground a little softer
:''Jump''
:Cueball: Until I
:''G l i d e''

:[In the second panel Cueball (five drawings) glides over a fence and the dunes before the beach — then he glides out over the sea. The fourth Cueball just passing over the sea looks back towards the shore. Four birds are flying behind him around the coast line.]

:[In the third panel Cueball (four drawings) glides across the open sea — three birds circling around the first Cueball, a fish is jumping out of the water splashing down again beneath the second Cueball.]
:''sploosh''
:Cueball: ...I ''hope'' this is a dream.

==Trivia==
*The title text for this comic originally read "I hope I'm at least following the curve of the Earth around to land..."
**But later it was changed to "Or that I'm at least following the curve of the Earth around to land..."
**This made it fit with the last sentence in the main comic:
:::...I ''hope'' this is a dream.
:::Or that I'm at least following the curve of the Earth around to land...

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Dreams]]
[[Category:Animals]]

343: 1337: Part 3

2024-05-09T23:17:55Z

Lemondoge: Adrian Lamo is dead, use "was"

{{comic
| number = 343
| date = November 14, 2007
| title = 1337: Part 3
| image = 1337 part 3.png
| titletext = I once asked an NSA guy whether they'd broken RSA. And I know I can trust him, because I asked if he was lying to me and he said no.
}}

==Explanation==
This is the third part of five in the "[[:Category:1337|1337]]" series. The title 1337 is "L-eet," or "elite," using the {{w|Leet}} alphabet, a coding system used primarily on the internet (and on early text messaging systems), meant to provide a bit of {{w|obfuscation}} to plain text both to make it harder to read and to show off in a creative way using in-group jargon.

This series was released on five consecutive days (Monday to Friday) and not over the usual schedule of three comics a week. These are all the comics in [[:Category:1337|1337 series]]:
* [[341: 1337: Part 1]]
* [[342: 1337: Part 2]]
* [[343: 1337: Part 3]]
* [[344: 1337: Part 4]]
* [[345: 1337: Part 5]]

The comic is narrated by [[Cueball]] as seen in the previous comic, but that Cueball is not shown here, where the man drawn as Cueball is a real person. {{w|Adrian Lamo}} was a hacker known for being a threat analyst and has penetrated many corporate networks. As far as we know, he has not penetrated any government networks, so helping [[Help I'm trapped in a driver's license factory Elaine Roberts|Elaine]] physically break into the {{w|NSA}} would probably inspire second thoughts. The use of a rug to cross the barbed wire fence is likely a reference to a scene in ''{{w|Fight Club}}'', where the same method is used to break into a {{w|liposuction}} clinic.

{{w|RSA (algorithm)|RSA (the algorithm)}} is an encryption algorithm that allows encryption and decryption using {{w|Public-key cryptography|separate keys}}. No efficient method to {{w|RSA problem|break RSA}} is known.{{Citation needed}} But if the NSA knew any such method, it would be unlikely for them to admit that.
However, the NSA have paid {{w|RSA Security|RSA (the company)}} to put a [http://theverge.com/2013/12/20/5231006/nsa-paid-10-million-for-a-back-door-into-rsa-encryption-according-to backdoor] into one of their encryption schemes. {{w|Lawrence Lessig}} is a political activist focusing on copyright law and intellectual property, as well as a founding board member of {{w|Creative Commons}}.

[[Steve Jobs]] was the two-time {{w|CEO}} of {{w|Apple Inc.}} In partnership with {{w|Steve Wozniak}}, he founded Apple. He oversaw Apple's return from near bankruptcy, the introduction of the original Macintosh, the {{w|iPod}}, the {{w|iPhone}}, and the {{w|iPad}}. But in the '90s, most of this had not happened yet. The comic is implying that it was Elaine, in fact, who planted those ideas in Jobs' mind (while perching on his bedpost, a nearly-impossible physical task for even a relatively small and light human being - such a stance is often depicted for gargoyles or fictional vampires, the latter of which are associated with nocturnal bedroom-invasions like this). Furthermore, Steve's reactions indicate that he was abruptly woken up by Elaine after she broke into his home and started a one-sided conversation with him.

The final panel is a pun on the Riot grrrls - {{w|Riot grrrl}} is an underground feminist punk rock movement. This metamorphosizes in the hands of Randall into Riot Prrl - who presumably prefer to code in {{w|Perl}}. The [https://www.facebook.com/Riot-Prrl-219590338058369/ real Riot Prrl] is from {{w|Northampton}} and is into {{w|Yarn bombing|guerilla knitting}}.

The title text may refer to the {{w|urban legend}} that leads petty criminals to ask each other [http://www.snopes.com/risque/hookers/cop.asp "Are you a cop?"]. The bottom line is that anyone who is capable of lying about breaking the RSA encryption algorithm, possibly including the "NSA guy," would be equally capable of lying about whether or not he is lying.

==Transcript==
:[Outside, Adrian Lamo is helping Elaine Roberts over a barbed wire fence.]
:It was the late 90's. Elaine crisscrossed the country with Adrian Lamo, the 'Homeless Hacker', learning to gain entry into systems both virtual and physical.
:Adrian Lamo: So you just throw a rug over the fence and... say, what ''is'' this place anyway?
:Roberts: Nowhere special.
:Lamo: ...Elaine, is this NSA Headquarters?
:Roberts: ...Look, I just want to see if they've broken RSA.

:[Inside, Lawrence Lessig is sitting at a table, Roberts is standing across the table swinging a knife.]
:She learned, from Lawrence Lessig, about the monstrosity that is U.S. Copyright Law.
:Roberts: So, how do we fix the system? Stab bad guys?
:Lessig: I'm starting something called "Creative Commons"
:''Shink''
:Elaine Roberts: I think we should stab bad guys...

:[Steve Jobs is lying up in his bed, Roberts is balancing while crouched on the foot of Jobs's bed.]
:She met with Steve Jobs to discuss the future of Apple.
:Roberts: Compression and bandwidth are changing everything.
:Jobs: Who are you? It's 3:00AM!
:Roberts: Apple should make a portable music player.
:Jobs: I'm calling the police.
:Roberts: Hey, idea — integrate it with a cell phone!

:[Scene has two of Elaine's activities. In one she is drumming, in the other she has an electric guitar on her shoulders, one hand on the frets. The other hand is holding a laptop by the touchpad.]
:She even, for a time, took up drumming, and helped start a movement among teen girls, a culture of self-taught female programmers and musicians, coding by day and rocking out by night—
:Roberts: Riot Prrl.

==Trivia==
This is the first xkcd comic featuring [[Steve Jobs]].

{{comic discussion}}

[[Category:1337|03]]
[[Category:Comics sharing name|1337]]
[[Category:Comics featuring Help I'm trapped in a driver's license factory Elaine Roberts]]
[[Category:Comics featuring Cueball]] 
[[Category:Comics featuring real people]]
[[Category:Comics featuring Steve Jobs]]
[[Category:Computers]]
[[Category:Cryptography]]
[[Category:Puns]]
[[Category:Music]]
[[Category:Fight Club]]
[[Category:CC-BY-SA comics]]

2753: Air Handler

2023-03-25T02:59:00Z

Lemondoge: /* Transcript */ added italicization

{{comic
| number = 2753
| date = March 22, 2023
| title = Air Handler
| image = air_handler_2x.png
| imagesize = 591x228px
| noexpand = true
| titletext = It maintains odor levels in a normal familiar range, so if you open the windows and the air gets too fresh, it filters it through some dirty laundry samples to compensate.
}}

==Explanation==
{{incomplete|Created by an UNUSUAL AMOUNT OF BEES - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

[[Black Hat]] is demonstrating an air-conditioning unit that covers a wide-variety of air qualities, as opposed to a heater that just warms air, a filter that just removes dust or a dehumidifier with the main purpose of removing moisture from the air.

In many devices that manage certain atmospheric conditions in a building using one device, an operational range is usually defined, and not one number. For example, when using a {{w|heat pump}}, if the interior temperature drops below a preset lower limit, then the heating function would be activated. If the interior temperature rises above another preset upper limit, the cooling function would be activated. This kind of ranged function is common with humidifier/dehumidifier units as well, to create a comfortable condition not too dry nor damp for comfort. By specifying upper and lower limits for the operation of the device in question, minor variations of the controlled value will not cause the device to be rapidly turning on and off, even working against itself, improving efficiency and reducing unnecessary wear and tear on the device and the building contents.

Devices that manage temperature and humidity are often installed in buildings to improve occupant comfort. Beyond that, the listed qualities become increasingly problematic and even dangerous.

Changing the pressure of the air could lead to <s>unintended</s> effects like large winds blowing through any cracks in the building.

The air handler also attempts to force the parameters of dust, smoke, odors, and number of bees into an "ideal" range. However, as opposed to being in a certain range, most people who live indoors prefer that these be minimized.{{fact}}

It is not particularly usual to directly monitor the number of bees in an air-stream (usually, insect-screens are the main way to filter out any pesky creatures that might find themselves likely to be caught up in that way), and one might imagine that the upper limit ''should'' be zero, for use indoors in standard living/working spaces, but it might be technically feasible to accurately count bees (with or without distinguishing from wasps and other flying insects) and be able to allow ''some''. But, unlike temperature or humidity, it would be rare (outside of a location used for agriculture) to have a non-zero ''minimum'' desirable quantity of bees. Even more so to then be directly equipped to upwardly correct the current value. For any minimum value that is not zero, this machine would be equipped to deal with it by, presumably, releasing bees (it seems to have at least one trapped inside it ready to be released, judging by the buzzing sound), or by generating smoke, dust and odors – something one would typically not miss if lacking.

As the title text elaborates, the machine analyses and adjusts the 'freshness' of the air. A smart system in charge of odor-control (by spraying smell-suppressing chemicals and/or more desirable and dominant scents) could be made less wasteful by only trying to 'freshen' the air when it detects enough necessity. But, of course, this machine also has an opposing limit. And, when the air is considered ''too'' fresh, it has a way of ''adding'' staleness/stinkiness, to meet expectations.

==Transcript==
:[Black Hat is standing to the right of an "air handler", talking to Cueball and Megan on the left side, probably presenting the sales pitch for the air handler in between them.]
:Black Hat: Our device monitors your home's air and keeps every variable between a lower and upper limit.

:[Zoom in on Black Hat]
:Black Hat: Temperature, humidity, pressure, dust, smoke, odors, number of bees...

:[Zoom out similar to Frame #1]
:Megan: Wait.
:Megan: What's the '''''lower''''' limit for "number of bees"?
:Black Hat: A normal amount.
:Air Handler: ''Bzzzzzz''

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Bees]]

1721: Business Idea

2023-03-21T01:16:19Z

Lemondoge: grammar fix

{{comic
| number = 1721
| date = August 17, 2016
| title = Business Idea
| image = business_idea.png
| titletext = Then we move to phase two. Gas stations store fuel in underground tanks. Normally, these are inaccessible except via the pump. However, with hydraulic fracturing, we-- Wait! Come back!
}}

==Explanation==
In this comic, [[Cueball]] announces he has "an exciting business opportunity to share". After hearing discouragement from his off-panel audience, he promises that "this time it's a good one", and goes on to explain his plan.

Cueball's plan involves the premise that a small amount of {{w|Octane rating|premium gas}} is left in a fuel pump hose after a car driver fills their car up with premium gas. He states that even if the next customer only pays for regular {{w|Gasoline|gas}}, that they are still getting a small amount of the expensive premium gas. Though he doesn't get a chance to finish the outline for his plan, one can assume he planned to get premium fuel at regular prices, so he could then sell it for profit. After hearing the first part of his plan, two people from the off-panel audience announce they are leaving, clearly and correctly thinking that Cueball's idea is stupid and impractical.

In reality, this would be an impossible business venture to execute. While in the United States often the same hose is used for the various octane fuels, the amount of fuel contained in the hose is relatively small (about [http://www.wsj.com/articles/SB122944043385810527 a third of a gallon], or [http://www.metronews.ca/drive/2012/05/08/one-pump-three-grades-how-does-it-know.html half a liter]) compared to the amount that is generally purchased, though [http://www.wsj.com/articles/SB122944043385810527 for motorcycles the ratio is more significant]. It is also illegal to resell fuel without the correct licenses, and it would be difficult, bordering on impossible, to have the fuel pump run to ''just'' the premium fuel out, and driving to each {{w|Filling station|gas station}} would use more money to buy more fuel than any money that could be made back. This is not to mention trying to keep track of when someone purchased premium so as to be the next person to use that pump to extract those precious drops.

[[1499: Arbitrage]] implies a similar plan to extract wealth out of a small market inefficiency that, in reality, would be far too onerous to exploit, in this case reselling the free chips offered at some restaurants. The same idea was also used in [[1110: Click and Drag]] where a person takes [http://imgs.xkcd.com/clickdrag/2n2w.png free drinks to resell]. See also the [[what if?]] ''{{what if|22|Cost of Pennies}}'' regarding why it would not be worth trying these kind of ventures out.

The title text is another one of Cueball's fuel-based business ventures, as he says he plans to dig up fuel stations underground fuel storage tanks, to then sell the contents of. Again, illegal/theft, impractical, don't try it (though it would be much more profitable than his previous plan). The punchline is that a gas station's underground tank is "inaccessible" from the outside, just as there are some oil deposits that are inaccessible to traditional oil production techniques because no sufficient natural flow towards a well can be obtained. In the case of oil deposits, high-pressure fluids are pumped into the rock to break it up ("{{w|Hydraulic fracturing}}" also known as "fracking") and allow the oil to reach the well. Oil tanks, on the other hand, can be made accessible by puncturing them using (presumably) hydraulically powered tools (electrical power is inadvisable in the presence of high-vapor-pressure hydrocarbons due to the significant risk of fire and explosion caused by electrical sparking).

The title text of [[1662: Jack and Jill]] also refers to fracking.

This comic originally shared name with [[827: Business Idea]], which was then renamed. There were no other relations between the ideas for the two comics, see [[#Trivia|Trivia]].

==Transcript==
:[Cueball is standing next to a rolled down projector screen holding a hand up towards his off-panel audience, one from the audience speaks. It is impossible to say if there are more than two persons off-panel, but it's also impossible to say if a person who speaks in one panel also speaks in one of the next, hence the numbering.]
:Cueball: Thank you all for coming.
:Cueball: I have an exciting business opportunity to share.
:Off-panel voice #1: Oh no.

:[Zoom in on Cueball's head. An off-panel person speaks twice.]
:Cueball: Now hear me out-
:Off-panel voice #2: Your ideas are always the worst.
:Cueball: No, no, this time it's a good one! I promise.
:Off-panel voice #2: Uh huh...

:[Front view of the screen with an image of a black gas pump, with the white hose snaking it's way up to the black handle. And arrow points to the middle of the hose where it is at it's highest point before the turn that goes to the handle. Cueball is pointing at the hose with a stick. Two different off-panel persons speaks to him.]
:Cueball: When someone fills their car with premium gas, some of it is left in the hose, and is dispensed to the next customer even if they've only paid for regular. If we create a network of-
:Off-panel voice #3: I'm leaving.
:Off-panel voice #4: Me too.

==Trivia==
*Because this comic had the same title (and filename) as comic [[827: Business Idea]], Randall inadvertently broke both xkcd.com and explainxkcd.com when it went up.
**The main xkcd.com site showed this comic for both numbers, while explainxkcd.com showed 827 for both.
**On 11:35 am UTC, Randall has fixed this by renaming the old comic to [[827: My Business Idea]].
*This is the third time Randall has released a comic with a [[:Category:Comics sharing name|name exactly the same]] as a previous comic.
**This is the second time the xkcd site broke. See more under [[:Category:Comics sharing name|the introduction to this category]].
*Not all gas stations leave the fuel in the hose; many pump it back into the tank for storage.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics sharing name|Business Idea2]]

2752: Salt Dome

2023-03-21T00:35:57Z

Lemondoge: Enhanced transcript.

{{comic
| number = 2752
| date = March 20, 2023
| title = Salt Dome
| image = salt_dome_2x.png
| imagesize = 422x338px
| noexpand = true
| titletext = The US uses hollowed-out salt domes to store the Strategic Petroleum Reserve, and non-hollowed-out ones to store the Strategic Salt Reserve.
}}

==Explanation==
{{incomplete|Created by Tsunami or Tidal Wave - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic refers to how downwards pressure in one area of the world can cause upwards pressure in another, causing {{w|salt domes}} to rise up.

In the comic, [[Beret Guy]] and [[Ponytail]] are sitting at a table and eating dinner, alongside [[Cueball]], who is presumably a {{w|geologist}}. Thus, when asked to "pass the salt," Cueball, with his extensive professional knowledge of the Earth's crust and its interactions with the surface world, is aware of this phenomenon, and as such is stomping on his chair in order to create downward pressure on the ground beneath. This apparently works exactly as intended, as a salt dome begins rising out of the floor and even begins to break through the dinner table. The caption humorously remarks that this is what will happen if you ask any geologist to "pass the salt," which conventionally means to simply hand a salt shaker or dispenser to another diner who cannot reach it (and a salt shaker can indeed be seen on their table).

Cueball also mentions {{w|overburden pressure}}, a geological term referring to the pressure that outer layers of rock exert on inner layers. This is what usually causes the rising of salt domes, though Cueball is employing it to an absurd degree here.

In the title text, the {{w|Strategic Petroleum Reserve}} is a United States government reserve of oil in case of emergencies. Randall observes the actually true fact that artificial caves within hollowed-out salt domes create the spaces for the government to store this oil. However, he then makes the not-quite-absurd, but still amusing remark that in turn, the fictional{{citation needed}} Strategic Salt Reserve simply consists of completely-intact salt domes, which obviously means they are full of salt and as such serve their function as a salt reserve perfectly.

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

:[Cueball, Beret Guy and Ponytail are sitting at a table. Beret Guy and Ponytail sit patiently; Cueball is stomping on his chair, and the ground has been dented very slightly by the legs of his chair. A white column of salt has burst through the ground and is rising up, slightly cracking and bending the table in the process. There are plates of food, drinking glasses, and a salt shaker on the table. One of the glasses has fallen, releasing what seems to be wine.]
:Cueball: Just a little more overburden pressure...
:Cueball: The dome is almost through the table...

{{comic discussion}}

[[Category:Comics featuring Cueball]]