explain xkcd - User contributions [en]

2581: Health Stats

2022-02-15T13:47:49Z

141.101.104.40: /* Transcript */ space

{{comic
| number = 2581
| date = February 14, 2022
| title = Health Stats
| image = health_stats.png
| titletext = You will live on forever in our hearts, pushing a little extra blood toward our left hands now and then to give them a squeeze.
}}

==Explanation==
{{incomplete|Created by a EXPLODING RIGHT HAND - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
[[Cueball]] has bought a new smartwatch with a health tracker. For instance it can monitor the volume of blood in his left hand, indicating this number in milliliters (ml). While he studies this new information, the volume of blood changes constantly, with his pulse or due to the positioning of his hand (above/below his heart, held up or down. He changes the hands position from panel to panel). He tells this to someone off-panel who replies to all his comments.

At first Cueball just assumes the small change is normal, but when the changes two measurements in a row increases, this freaks him out as he [[605: Extrapolating|extrapolate these two data points]] into the future, so if this continues his hand will explode from it's ever increasing volume of blood. As a consequence of him freaking out his pulse also begins to rise, likely increasing his blood pressure, which could cause another rise in the volume of blood in his hand. And the pulse increase in itself, only makes him even more scared, causing a positive feedback loop.

The total difference between the maximum (22.09 ml) and minimum volume (21.81 ml) of blood in his hand is only 0.28 ml compared to an average of 21,9 ml, so less than 1,5% difference. This must be assumed to be a normal fluctuation from heartbeat to heartbeat.

Just before he freaks out his off-panel friend begins to tell him to stop looking at the watch all the time. But he interrupts this mid sentence as he starts to freak out. This final outbreak causes his off-screen companion to tease him, by saying that "We will treasure your memory". Thus joking that Cueball most already be assuming that he will soon die from the blood loss when his hand explodes.

The title text continues with this teasing where the friend jokes that, after his demise he will live on forever in his friends hearts. And from there he will thus also be responsible for pushing a bit more blood into his friends left hand, now and again, so they can feel this as a squeeze, to remind them of how they lost their friend, to a left handed blood explosion.

This is likely meant as a parable on people monitoring their natural fluctuating body functions too closely as exemplified by the tenth and hundredth milliliter decimal place in the output (1/300th-1/3000th of a fl oz.).

==Transcript==
:[Cueball is looking down and to the right at his bend arm, where a small device is radiating as shown with several small lines. Above him the message from the device is shown in a frame, that is divided in two by a line. The top part has one line of text, with a x at the end for closing the message. And below in the second half are two lines of text. Cueball is speaking to someone off-panel, who replies from a starburst at the panels edge.]
:Box titlebar: New health stat!
:Box: Left hand blood volume: 21.83 mL
:Cueball: Oh. Cool. Not sure how to interpret that, but good to know, I guess.
:Off-panel voice: I guess!

:[Same setting but Cueball has turned to the left, still looking at his device on his bend arm. The message on the device is now only showing the message part, so it is no longer divided in to two parts.]
:Box: Left hand blood volume: 21.81 mL
:Cueball: Huh, it's going down. I guess that happens.
:Off-panel voice: Mhm.

:[In a frame-less panel Cueball now has both arms bend with his hands close together in front of him. He has once again turned toward the right, and is still looking at the device.]
:Box: Left hand blood volume: 21.86 mL
:Cueball: Oh weird, now it's going up higher than before.
:Off-panel voice: Maybe you shouldn't look at-

:[Cueball now holds his arm with the device outstretched towards the right, with his other arm bend in front of him a finger raised.]
:Box: Left hand blood volume: 22.09 mL
:Cueball: It's going '''''way''''' up! '''''Is my hand exploding?!'''''
:Cueball: And now my pulse is rising! '''''Aaaaa!!!!'''''
:Off-panel voice: So sorry. We will treasure your memory.

{{comic discussion}}

[[Category:Comics with lowercase text]]
[[Category:Comics featuring Cueball]]
[[Category:Biology]]

665: Prudence

2016-10-21T14:29:37Z

141.101.104.40: /* Explanation */

{{comic
| number = 665
| date = November 20, 2009
| title = Prudence
| image = prudence.png
| titletext = Moments later, the White Witch rolls up and, confused, tries to tempt the probe with a firmware upgrade.
}}

==Explanation==
This comic references the fantasy novel series "{{w|The Chronicles of Narnia}}" by {{w|C. S. Lewis}}. In the second book (and the first movie), four children discover the fictional world of Narnia which can be accessed through a wardrobe.

The comic mocks at the imprudent behaviour shown by the protagonists of the novel, who enter the world of Narnia without knowing anything about its dangers. In the comic, Megan discovers the magical wardrobe while playing {{w|hide-and-seek}}. Unlike the original characters, Megan does not precipitately set foot into Narnia. Instead, she fetches her technical equipment and sends a remote-controlled probe through the wardrobe door in order to sound the situation first.

This procedure of sending a probe first can be seen in the early Stargate episodes. This draws a parallel between the wardrobe in Narnia and the Stargate, both connecting two distant worlds. The stargate probe can be seen at http://stargate.wikia.com/wiki/Mobile_Analytic_Laboratory_Probe

The probe can be seen in the sixth and eighth panel, encountering {{w|Mr. Tumnus}} the faun with an umbrella at a lamppost in a snowy wood on the last panel. This picture is the first impression of Narnia in the novels and was apparently Lewis' original idea for the series.

The {{w|White Witch}} mentioned in the title text is the main antagonist in the novel. She originally lures one of the protagonists with a hot drink and {{w|Turkish delight}}. In the scenario displayed in the comic, she tries to tempt the probe with a firmware update accordingly.

Megan takes a scientific approach to Narnia again in [[821: Five-Minute Comics: Part 3|a later comic]].

==Transcript==
:[Megan is running towards a closed wardrobe.]
:Someone off-panel: Everyone hide! 99... 98... 97...

:[Megan opens the wardrobe.]
:Wardrobe: click

:Megan, looking inside: !!!

:[Megan looks thoughtful.]

:[Megan walks away.]

:[Megan returns with an armful of electronics.]

:[Megan is kneeling, typing on a laptop, which has a cord extending into the wardrobe.]

:[A robotic probe is approaching Mr. Tumnus, the faun, under the lamppost in narnia.]

{{comic discussion}}
[[Category:Comics featuring Megan‏‎]]

691: MicroSD

2015-02-01T09:28:16Z

141.101.104.40: Correct usage of units and spacing.

{{comic
| number = 691
| date = January 20, 2010
| title = MicroSD
| image = microsd.png
| titletext = That card holds a refrigerator carton's worth of floppy discs, and a soda can full of those cards could hold the entire iTunes store's music library. Mmmm.
}}

==Explanation==
{{w|MicroSD}} is one format of the Secure Digital memory card format, used in digital cameras, cell phones, and other devices. It is very small, only 15×11×1 mm, but can hold as much as 128GB of data (as of January 2014).

The main character in the comic (on the right) thinks about all the ideas that could be expressed by the data in the microSD card, or in a library. He feels not just reverent and intimidated, but sexually aroused by the thought. As he begins to touch it, his friend is disgusted by what might happen if he uses the card as some kind of sex toy, and does not want to be involved if the card is lost afterwards (or ends up in some bodily cavity (or both)).

The title text seems to be the main character thinking about how much data the card holds, in terms of {{w|floppy disks}} and the {{w|iTunes}} music library, and feeling aroused by these thoughts.

Randalls claims in the title text do check out. A high density floppy disk with a FAT format holds about 1.4 MB of data, and has dimensions of 90×94×3 mm, for a volume of about 25 cm³. A refrigerator carton is the large cardboard box that fridges are delivered in. A typical refrigerator carton may be 1800×700×700 mm, a volume of about 9 m³. So a fridge carton could hold about 35000 90mm floppies, or roughly 50GB. This is comparable to the storage on a single microSD card. A soda can (1 ml = 1 cm³) could hold 3000 microSD cards, or store 50TB of data. However, the iTunes store claims to hold 26 million songs (as of Summer 2014), and allowing for about 2MB per song gives 50 TB of music. The claim that a soda can could hold the iTunes library seems to be reasonable.

Related to this topic is [http://what-if.xkcd.com/31/ this xkcd What If blog entry].

==Transcript==
:[Cueball and a friend approach a table.]
:Cueball: Hey, what's up?
:Friend: Shhhhh.
:Cueball: Hrm?
:Friend: There's a microSD card on your table.

:[A microSD card sits next to an assortment of coins for size reference.]
:Cueball (out of panel): So?
:Friend (out of panel): I dunno, high storage densities freak me out. A whole aisle of library shelves on something smaller than a dime.

:[The two people stand near the table, the friend peering at the coins and card on the table.]
:Friend: Libraries are unnerving enough-millions of ideas surrounding you, towering over you. These cards fill me with that same reverence, that same intimidation.

:[Cueball stands alone.]
:Friend (out of panel): ...that same faint arousal. Maybe I'll just touch it.
:Cueball: If you lose that card I'm NOT helping you find it.

{{comic discussion}}
[[Category:Comics featuring Cueball]]

Talk:1381: Margin

2014-06-24T13:09:14Z

141.101.104.40:

Isn't it possible that a mathematician knows about the existance or the proof of something, but doen't know how to technically do it? In this case, the margin remark would be accurate and not so funny. They have found a proof of existance for infinite information compression, but not yet discovered an actual method to do it. [[Special:Contributions/141.101.104.56|141.101.104.56]] 05:32, 13 June 2014 (UTC)
:Yes, when there's no example, it's called a {{w|pure existence theorem}}. If you actually demonstrate an example, that is a {{w|constructive proof}}. [[User:Mattflaschen|Mattflaschen]] ([[User talk:Mattflaschen|talk]]) 05:38, 13 June 2014 (UTC)
::Actually the proof of the Shannon-Hartley theorem is non-constructive. It tells you the data rate of the best possible channel coding, but does not tell you how to achieve it! [[Special:Contributions/108.162.215.47|108.162.215.47]] 07:58, 13 June 2014 (UTC)
Setting font-size to 0 would be the same as not ''printing'' any information at all, you'll still use the same number of bits and be able to send the text to other computers which can read the information. The Shannon-Hartley theorem is, as far as I can see from the wikipedia article, about analogue channels anyway. --[[User:Buggz|Buggz]] ([[User talk:Buggz|talk]]) 06:16, 13 June 2014 (UTC)
:The Shannon-Hartley theorem is about sending digital data (over analogue channels but you cannot send them over anything else in real world anyway). Nevertheless, you are right that setting the font size won't change the number of bits needed to be sent (font size specifies the size of the representation, not the information itself) therefore it won't change the limit. [[User:Sten|'''STEN''']] ([[User talk:Sten|talk]]) 22:12, 13 June 2014 (UTC)
::If you consider the paper itself as an analogue channel, then setting the font size to 0 before printing on the paper will "compress" information of any length to a single white sheet of paper. Decompressing it is not that difficult, but the method is a bit too large to fit here.[[Special:Contributions/141.101.104.40|141.101.104.40]] 13:09, 24 June 2014 (UTC)

Isn't this also a reference to {{w|Jan Sloot}}'s digital compression mechanism where a movie would fit into 8 kbyte? [[User:Kaa-ching|Kaa-ching]] ([[User talk:Kaa-ching|talk]]) 07:36, 13 June 2014 (UTC)

This was my first time editing Explain XKCD, but I fear I may have went too far in replacing the current explanation of the title-text with my own and removing the incomplete tag. Is it OK? [[User:YatharthROCK|YatharthROCK]] ([[User talk:YatharthROCK|talk]]) 08:10, 13 June 2014 (UTC)
:I think you title text explain seems fine (I have not checked on the Shannon theorem.) But I think it is too soon to make this explain marked as complete. So I have undone that. Great to have one more to edit the explain so keep up the good work. [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 10:46, 13 June 2014 (UTC)

Is the problem behind Fermat's Last Theorem "deceptively simple" or "deceptively difficult"? I've never quite worked out which way it should be. Unlike "cheap at half the price" which really should be "cheap at twice the price" and the effect of putting in the word "only" into "glass ... half full/empty". But I bet you all could care less (or, more accurately, "''couldn't'' care less", because you already do not care at all), right? ;) [[Special:Contributions/141.101.98.232|141.101.98.232]] 11:44, 13 June 2014 (UTC)
:I believe the correct wording would be "deceptively difficult". Deceptively simple would imply that the problem looked quite difficult on the surface, but once work had begun it was found to be quite simple. Fermat's last theorem goes the other way. It is simply stated with very few elements, so it would seem the proof should be easily constructed, but is actually quite difficult. {{unsigned ip|173.245.50.72}}
::Unfortunately "deceptively easy" could also mean the opposite: it's easy, but only as a deception, so it's actually difficult. As of now, not even linguists have settled the question. It is just better to avoid the word unless the context can disambiguate the meaning. [[Special:Contributions/141.101.99.32|141.101.99.32]] 05:14, 14 June 2014 (UTC)

Is it at all possible that the exclamation: "oh," represents the discovery of an earlier proof (perhaps even better than the one purported) all ready in the margin? That would explain the next exclamation: "never mind." This is a comic after all. And what's with the unreadable Lorem Ipsum text (perhaps a proof in itself)? Of course, the unhappy face (after "never mind") is a visual image compression mechanism that may deserve comment as well. [[User:Run, you clever boy|Run, you clever boy]] ([[User talk:Run, you clever boy|talk]]) 14:36, 13 June 2014 (UTC)

;Why bury descriptions of the beautiful inspiration behind these great comics in an afterthought "trivia" section?

I think explanations of the beautiful inspirations for these comics (like Fermat's last theorem, here) should be highlighted in the main part of the article, not buried below the transcript and demeaned with the label "trivia". [[User:Nealmcb|Nealmcb]] ([[User talk:Nealmcb|talk]]) 12:46, 13 June 2014 (UTC)
:Well there is a link from the relevant part. The inspiration of this comic is that someone wrote a statement in a margin and did not have space for the proof. It is not the theorem in it self that is the inspiration. Writing about Phytagoras and formulas in the explain is maybe a little too much. I think it belongs well in the trivia section and it is not buried - with this short transcript you can easily see there is more to the explai. [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 05:49, 14 June 2014 (UTC)

"" leading many to believe that he didn't actually possess a (correct) proof"" Of course Fermat did not have a proof.
Was that margin the only free piece of paper in France then?
For that reason in German one does not speak of Fermats "theorems", but the names used are
Fermat's little or resp. big problem. If some nobody had written that margin, of course
that would have been named a conjecture at best. Because Fermat was a real "big shot",
a medium expression is used: "problem". But never theorem, because a theorem without
proof isn't a theorem.
17:18, 14 June 2014 (UTC)[[Special:Contributions/108.162.254.138|108.162.254.138]]
:Who says he did not write his proof somewhere else, on a paper that was lost. It is only because the book was easily sored that we have all of Fermat's theorems. There were many in his book, and all of them - including the last - turned out to be true theorems. I do not believe he had the proof - but that is beside the point. If it had been a nobodu, then the book would never have been investigated... Anyway this has of course nothing to do with this explanation - but an interesting observation here in the talk page ;-) [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:11, 15 June 2014 (UTC)

What if the margin text is the compiled form of the proof? [[Special:Contributions/141.101.105.187|141.101.105.187]] 04:46, 15 June 2014 (UTC)
:Then he would not have written the oh... :( never mind [[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:11, 15 June 2014 (UTC)
::Maybe the "oh... nevermind" is part of the proof... --[[Special:Contributions/108.162.254.185|108.162.254.185]] 10:31, 15 June 2014 (UTC)
:::And maybe you had a point, but I'm afraid neither seems very likely ;-) Davii [[Special:Contributions/141.101.99.189|141.101.99.189]] 23:49, 15 June 2014 (UTC)
::The "'''oh... :( nevermind'''" is simply the key required to decrypt the proof. {{unsigned ip|103.22.201.239}}
:::You are right, I just decoded it using that key! I'm afraid the full text of the proof is quite large and can't fit here.[[Special:Contributions/108.162.218.71|108.162.218.71]] 12:58, 24 June 2014 (UTC)