https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=172.70.34.105&feedformat=atomexplain xkcd - User contributions [en]2024-03-29T09:54:03ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=2626:_d65536&diff=2848082626: d655362022-05-31T20:09:55Z<p>172.70.34.105: /* Explanation */</p>
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<div>{{comic<br />
| number = 2626<br />
| date = May 30, 2022<br />
| title = d65536<br />
| image = d65536.png<br />
| titletext = They're robust against quantum attacks because it's hard to make a quantum system that large.<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a HEXAKISMYRIAPENTAKISCHILIAPENTAHECTATRIACONTAKAIHEXAHEDRON - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
In binary computing, 16 bit numbers range from 0 to 65535, for a total of 65536 unique numbers, a number which is hence well-known to software engineers. Generating large numbers in a manner that is truly random is a recurring problem in cryptography, required to send private messages to another party. People today still use dierolls to generate private random numbers.<br />
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In role-playing games (and occasionally in other tabletop games), dice are often referred to as d[number] according to their number of faces. A traditional six-faced die would be a d6, and many popular pen-and-paper role-playing games use dice ranging between d4 and d20. While there are larger dice used in tabletop games (most commonly d100), these are usually split into multiple smaller ones to save the hassle of throwing large dice. For example, a d100 is often two d10s rolled together, with one die providing the first digit and the other die giving the second digit — the total number of possible combinations (100) is the product of the number of faces of the two dice (10 * 10). There are, however, "real" {{w|Zocchihedron|d100s}} and similar dice as well, but they are considered specialty dice and often nicknamed "golf balls" to emphasize how large and unwieldy they are.<br />
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Here, Cueball has constructed a d65536 for generating random 16 bit numbers, likely with a [https://www.shapeways.com/product/U9CN6MT6X/d256 3d printer] or other CAM tools. It may have solved the problem of generating large random numbers with fewer die rolls, but presents a new set of challenges from its sheer size, dwarfing an average human. While large in itself, a die that big could still be emulated by rolling multiple dice (e.g. 8 4-faced dice or 16 coin flips) and converting the result into binary before getting the desired number. Part of the humor stems from the the comic completely failing to mention another big problem with this die: Deciding which of the 65536 faces is up. This is another problem with a d100, as many sides appear to be up at once. Similarly horrible hilarity will ensue if such a massive die is cast with enough energy to be random while expect it to stop rolling in a short period of time let alone on a table top or even within a building (which raises the question of whether breaking through a wall or furniture is all part of the randomization or requiring a re-roll as per house rules). <br />
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The closest regular shape similar to the depicted in the comic could be a {{w|Goldberg polyhedron}}. However no such polyhedron exists with exactly 65536 hexagonal faces. The closest Goldberg Polyhedron has a mixture of 65520 hexagons and 12 pentagons, totalling 65532 faces. It is possible to construct a fair die without a matching regular shape by limiting the sides which it could land on and designing those sides to be fair (for instance, a prism with rectangular facets that extend its entire length, and rounded ends to ensure it doesn't balance on end).<br />
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The title text references how many cryptographic systems (especially RSA and other factoring-is-hard based systems) are vulnerable to quantum attacks as quantum computing technology develops. The title text is essentially punning on the idea of a "large" quantum system. "Large" in the quantum computing sense would be on the order of 64 qubits each of which would be an atom or two at most. This would still be microscopic and will never be as large as the giant die the comic is centered on; but for a well-observed environment and human rolling without sufficient entropy (consider somebody obsessed with a certain number dropping the die on something soft), a conventional computer could predict some rolls. See also [[538]] for non-mathematical paths of cryptography.<br />
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==Trivia==<br />
*If a real d65536 were constructed with each number having an equal area and each printed in 12 point font, the resulting die would be about 5 feet (1.5 meters) in diameter, which isn't several times the size of a person as the comic suggests, but is still large enough to be hilariously inconvenient. If it were made out of standard acrylic, and not hollow, it would weigh about 2 tons (1700kg).<br />
*This die would have a 0.00001526 chance of rolling a natural one (or any other number).<br />
*There are seven 16-bit numbers fully visible in the picture: 30827, 25444, 11875, 28525, 12082, 13874 and 13359. They conceal a message. If these numbers are split big-endian into two 8-bit ASCII characters each, the result is <code>xkcd.com/2624/</code>.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Drawing of a large die with many sides, about ten meters in diameter; Cueball is standing next to it as a size reference. A small portion of the die's surface is zoomed in, showing elongated hexagonal faces with five-digit numbers.]<br />
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:[Numbers on the zoomed in part of the die, "..." represents being cut off:] <br />
:30827 <br />
:16[bottom part of a line][small circle] <br />
:...38 <br />
:11875 <br />
:25444 <br />
:...[top part of a line]5 <br />
:12082 <br />
:28525 <br />
:3... <br />
:13359 <br />
:13874 <br />
:2...<br />
<br />
:[Caption below the image:]<br />
:The hardest part of securely generating random 16-bit numbers is rolling the d65536.<br />
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{{comic discussion}}<br />
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[[Category:Cryptography]]<br />
[[Category:Comics featuring Cueball]]</div>172.70.34.105https://www.explainxkcd.com/wiki/index.php?title=2623:_Goofs&diff=2843282623: Goofs2022-05-27T19:33:42Z<p>172.70.34.105: /* Explanation */</p>
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<div>{{comic<br />
| number = 2623<br />
| date = May 23, 2022<br />
| title = Goofs<br />
| image = goofs.png<br />
| titletext = The film is set in 2018, but when Commander Bremberly chases the hologram through Times Square, there's a billboard for Avengers: Age of Ultron. Depending on the date, that billboard would have been advertising either Infinity War or this movie.<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a IN THE EVENT OF DIFFERENCES BETWEEN REALITY AND FICTION REALITY IS WRONG - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
IMDb is the {{w|Internet Movie Database}}, a website that contains detailed, user-contributed information about movies and TV shows. One of the sections in many entries is "[[#Goofs|Goofs]]". This may list bloopers, inconsistencies, implausible actions, anachronisms, etc. in the movie. While some people find enjoyment in searching for these errors, to others, the entries listed can often be overly pedantic and missing the point{{Citation needed}} (a problem that can often afflict sites that rely on users to provide their content [Hey! Who you calling a pedant?]). The comic makes fun of this with several goofs that simply point out differences between something in the movie and reality; but since the movie is fiction (in this case, a science fiction film that includes a space detective, a cybernetic dog, blimp drones, and a hologram kissing scene), one can say that these "goofs" might simply be more differences between the movie world and our own.<br />
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In the first goof, a named street doesn't actually exist in the city in which the movie is set. Unless the address is important to the plot (Manhattan has a number of streets with well-known characters - for example, the main theatre district is on Broadway, Fifth Avenue is a major shopping district, and Wall Street is known for large financial institutions), screenwriters can and do make up street names. It might actually be expedient to 'rename' a setting in many cases, to avoid issues such as fans showing up at said street and harassing the residents.<br />
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In the second example, they point out that there's no harpoon store at the location where the characters obtain a harpoon in the movie, and the nearest actual harpoon store doesn't have a display window. Movies take liberties with details like this for plot expediency, and is not considered a goof. Manhattan does not appear to have ''any'' notable harpoon stores, with or without the kind of frontage described.<br />
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In the third example, the background of a scene is of an apartment in Downtown Vancouver (a cheap and popular filming location that frequently stands in for other cities). The goof points out that the real-life apartment does not belong to the character who supposedly lives in it. Fictional movie characters do not exist in reality,{{Citation needed}} and many scenes are set in fictional locations that are completely separate from their real-life filming locations. As such, this is only a "goof" if the scene is taken entirely literally.<br />
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The title text describes an actual anachronism. The film is set in 2018, but there's a billboard for the movie ''{{w|Avengers: Age of Ultron}}'', which came out in 2015, while the next Avengers film, ''{{w|Avengers: Infinity War}}'', came out in 2018. Assuming the movie was filmed before 2018, the filmmakers wouldn't have known what films would be current at the time it would be released, and certainly not the artwork they'd be using to promote them. They could have chosen to set it during the time of initial filming, but again, unless the specific date is significant to the plot, it's common to set (or rather, assume) a film takes place about the same time it's released. Generic advertisements for fictional (or {{w|Last Action Hero|parody}}) films might be put over egregiously obvious existing material, physically or in post-production editing, as might references to major brands – perhaps replaced by those agreed with from {{w|product placement}} partners.<br />
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The title text also mentions the possibility of a self-reference – the billboard could be for this film itself since it's being released at the same time it's set. This assertion that {{w|Blazing Saddles|in-universe self-reference}} is plausible for a movie production is likely another example of the goof's writer failing to understand the basic "premise of fiction". Most movies do not exist within the fictional world they portray,{{Citation needed}} and many audiences would find self-reference to be a far greater obstacle to suspending disbelief than an ad for the wrong Avengers movie.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[An excerpt from an Internet Movie Database web page showing a list of goofs from a film. Each item has some small illegible text below it, which on the real IMDb would say something like "7 of 72 found this interesting | Share this". The first and third items have a faint yellow-tinted background. The third item is only partially visible at the bottom of the "screen".]<br />
:[Heading:]<br />
:<big> Goofs (78) </big><br />
:[List:]<br />
:The space detective's office is on Chestnut Ave, but Lower Manhattan has no street by that name. Agent Glennifer pursues the cybernetic dog onto what is clearly Ludlow Street.<br />
:The agents destroy the blimp drones in Union Square with harpoons from a store display rack. The nearest harpoon store is several blocks away and has no outdoor displays.<br />
:The apartment in the background of the hologram kissing scene actually exists in downtown Vancouver. We called the owners, who confirmed they had no residents named [...]<br />
<br />
:[Caption below the panel:]<br />
:Sometimes the IMDB "Goofs" section really seems to struggle with the whole premise of fiction.<br />
<br />
==Goofs==<br />
* There is no entry for a film featuring an agent called Glennifer or a commander named Bremberly on IMDb. Randall is clearly failing to do basic research.<br />
* On the real IMDb, each item in the Goofs section would be listed under a category such as "Errors in geography" (which might apply to the three goofs listed in the main cartoon) or "Anachronisms" (which might apply to the goof in the title text). However, no such category is displayed here.<br />
* On real Goofs pages, the information below each entry includes a public feedback listing (X of Y found this interesting) and a link entitled "Share this". In the comic, only unintelligible squiggles are included in their place, which really breaks the immersion of the purported "webpage". Of course, on a real IMDb page, all of the text would also be in the Verdana font, not Randall's handwriting.<br />
* The comic features two entries with a yellow background, which is impossible. On IMDb, entries alternate between having white and gray backgrounds and only turn yellow when the mouse hovers over them.<br />
* On IMDb, the number of goofs is located in a navigation box between the header and the goofs list. In the comic, the number is placed in the header, and there is no navigation box at all.<br />
* A similar Goofs section exists in the [[explain xkcd]] wiki's page for this comic, [[2623: Goofs]], but it fails even more evidently to recreate the look of IMDb's Goofs page. Additionally, the last entry is recursive, which is clearly unprofessional.<br />
* The penultimate entry is also recursive leading to a form of pairwise recursion and formal structure subject to analysis not typically associated with goofs sections in their generalized forms.{{Citation needed}}<br />
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{{comic discussion}}<br />
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[[Category:Comics with color]]<br />
[[Category:Fiction]]</div>172.70.34.105https://www.explainxkcd.com/wiki/index.php?title=Talk:2624:_Voyager_Wires&diff=276927Talk:2624: Voyager Wires2022-05-25T21:24:58Z<p>172.70.34.105: </p>
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<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
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This is fun - assuming a pair of 14ga wires were run the 14.5 billion mile distance from Earth to Voyager 1, the mass of copper would be on the order of 10<sup>12</sup> kg, or ~5 times the mass of copper ever mined out of the earth. [[Special:Contributions/172.70.126.87|172.70.126.87]] 17:18, 25 May 2022 (UTC)<br />
:Wow, that's a lot of copper! I wonder how they've been communicating with the probes up until now? :) [[User:Danny E. Corchado|Danny E. Corchado]] ([[User talk:Danny E. Corchado|talk]]) 20:46, 25 May 2022 (UTC)<br />
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At current prices for copper, this spool would cost ~9.6 trillion dollars. Surprisingly, that's only about a third of the US national debt. --[[User:KrazyKat|KrazyKat]] ([[User talk:KrazyKat|talk]]) 17:29, 25 May 2022 (UTC)<br />
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The problem of the Earth spinning could be solved by putting the contact at one of the poles; it will have to be on a swivel joint to prevent it from twisting. But there's also the Earth revolving around the Sun, which requires the cable length to cycle up and down by 186 million miles every year. I guess we could use a big version of dog leash holders. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 17:44, 25 May 2022 (UTC)<br />
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Days before this comic was published, NASA reported issues with Voyager 1, reporting that "the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard"<br />
[https://www.jpl.nasa.gov/news/engineers-investigating-nasas-voyager-1-telemetry-data]<br />
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If they used wires and it was due to budget constraints, why not reel the Voyager probes back in and recycle the wire? [[Special:Contributions/108.162.245.173|108.162.245.173]] 19:24, 25 May 2022 (UTC)<br />
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Quick calc+google - world copper reserves are estimated at 870 million tonnes, Voyager 1 is 14,471,238,963 miles from Earth (Voyager 2 a bit closer, 12 x 10^9 miles)... a lot of unit conversions and simple arithmetics later... World copper reserves would be enough for a cable with about 4 mm^2 cross-section (2,3 mm diameter) for one of them or 2.3 mm^2 cross-section (1,7 mm diameter) cables to both. Someone check the math please, it's been a long day... [[Special:Contributions/172.68.110.139|172.68.110.139]] 19:31, 25 May 2022 (UTC)<br />
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This is a comic worth a What-If-article. Even with zero friction extraction systems and enough available copper, there is the problem of the speed you need to send out new wire. Voyager is moving at ca. 17 km/s and Earth moves at about 30. So when Earth and Voyager move in opposite directions you have to produce *a lot* of wire per second in order to keep up with that (not exactly 47 km/s because Voyager is moving away from the ecliptic. [[User:Kimmerin|Kimmerin]] ([[User talk:Kimmerin|talk]]) 19:53, 25 May 2022 (UTC)<br />
:Yes, definitely worth a What If! Randall, if you read this, please write a What If article on this! [[User:Danny E. Corchado|Danny E. Corchado]] ([[User talk:Danny E. Corchado|talk]]) 20:47, 25 May 2022 (UTC)<br />
::Maybe this is a sly advertisement for an existing article in the forthcoming book! :) [[Special:Contributions/172.70.34.105|172.70.34.105]] 21:24, 25 May 2022 (UTC)<br />
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Voyager 1 and 2 communicate with each other, or with Earth? --[[Special:Contributions/172.70.126.65|172.70.126.65]] 20:27, 25 May 2022 (UTC)</div>172.70.34.105