explain xkcd - User contributions [en]

2626: d65536

2022-06-01T07:05:58Z

172.68.50.237: Image should be as that on xkcd.com/2626

{{comic
| number = 2626
| date = May 30, 2022
| title = d65536
| image = d65536.png
| titletext = They're robust against quantum attacks because it's hard to make a quantum system that large.
}}

==Explanation==
{{incomplete|Created by a HEXAKISMYRIAPENTAKISCHILIAPENTAHECTATRIACONTAKAIHEXAHEDRON - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
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.

In role-playing games (and occasionally in other tabletop games), dice are often referred to as d''n'' 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. The Zocchihedron (d100) die is also biased because of geometry requiring different sized faces, the next unbiased die is a d120, it is very likely that Cueball's d65536 die is also biased.

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).

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, totaling 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).

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.

==Trivia==
*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).
*This die would have a 0.00001526 chance of rolling a natural one (or any other number).
*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>.

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

:[Numbers on the zoomed in part of the die, "..." represents being cut off:]
:30827
:16[bottom part of a line][small circle]
:...38
:11875
:25444
:...[top part of a line]5
:12082
:28525
:3...
:13359
:13874
:2...

:[Caption below the image:]
:The hardest part of securely generating random 16-bit numbers is rolling the d65536.

{{comic discussion}}

[[Category:Cryptography]]
[[Category:Comics featuring Cueball]]

2572: Alien Observers

2022-01-25T16:50:50Z

172.68.50.237: +Category:Comics referencing THX 1138 (someone should create the category, I can't because I'm not able to recover my account pwd)

{{comic
| number = 2572
| date = January 24, 2022
| title = Alien Observers
| image = alien_observers.png
| titletext = ALERT: Human 910-25J-1Q38 has created a Youtube channel. Increase erratic jerkiness of flying by 30% until safely out of range.
}}
*This was the seventh comic to come out after the [[Countdown in header text]] started.

==Explanation==
{{incomplete|Created by a BLURRY MARTIAN SPACECRAFT- What does they mean by did they not just upgrade, and I know I know. Seems weird to say of one person buying a camera. What about all others? Also, what's 910-25J-1Q38, a phone number? Please change this comment when editing this page. Do NOT delete this tag too soon.}}
There is speculation by many people that there could be some form of extraterrestrial life observing us, hovering around in various flying vehicles, or perhaps using some form of giant telescope. These claims are often backed up by blurry pictures which claim to be of alien vehicles. In this comic, the joke is that the aliens are deliberately making sure that all sightings are made unverifiable. However, with [[1235:_Settled|most people now carrying a camera with them all the time]], a sighting that would be unverifiable just by eyewitness testimony could now be captured by a smartphone camera.

This means that in order for the aliens to keep creating unverifiable sightings for humans, they must keep track of what camera capabilities each human has, leading to different distance restrictions for each human, as seen in the diagram. The effective range of each person's camera is depicted as a circular (or spherical) envelope around themselves, two on the cross-sectional diagram and at least one located off beyond the image edge.

There is also an apparently flat ground-hugging 'no fly zone' connecting two of these areas. This may be part of a general prohibition against landing (and/or causing verifiable ground effects, such as {{w|crop circles}}) or it could be there to show that the capability of a self-focussing camera is greatly enhanced when it also has ground-features to autofocus upon rather than a subject surrounded by nothing but sky.

The comic attempts to explain away the issue already discussed in prior comics, such as [[718: The Flake Equation]] and [[1235: Settled]], in which the phenomenon of UFO sightings/reports is still left not resolved (either way) despite what modern technology should suggest is possible. It appears that the reason for this is that the {{tvtropes|SufficientlyAdvancedAlien|sufficiently advanced aliens}} actually make more than enough observations of the human race to continuously determine how to stay just on the side of plausible deniability in any interactions that they still seem to wish to make.

The attitude of the aliens also mirrors that of a subset of humans, namely those who hold disdain for the {{w|consumerism|consumerist}} mindset. These humans are frustrated by the tendency of their fellow humans to compulsively buy the latest and greatest versions of products at all times, often at great expense and without regard for the practical benefits of upgrading. Cellphones are one such product, as Apple and their competitors typically release new phone models annually (occasionally semi-annually), often introducing only minor or cosmetic changes with each new iteration.

In the title text, the aliens note that one particular human now has a YouTube account, meaning they are likely to record video instead of attempting to capture still images. This means that the alien craft used to create the sighting must behave as erratically as possible, in order to avoid being identified. This relates to the often wildly oscillating (as well as blurry) films and videos of 'UFOs' that have been taken by the impromptu human observer, beyond the limit of their ability to hold their fully-zoomed camera steady. Although here it is explained away as the flying saucers ''actually'' moving in an improbably jerky manner to prevent detailed recording of their craft. Further briefings of the sort depicted would doubtless accompany upgrades in optical/digital-stability features or the purchase of a camera tripod.

It appears the aliens have a classification and tracking system for all humans. It is unclear what the system for assigning these identifiers is, since we see two different formats (''38XT11-B-C54'' and ''910-25J-1Q38''). One possibility is that there are two different tracking systems represented, with at least two possibilities for the relation between them.
# Perhaps the two tracking systems are from two different alien agencies dedicated to human tracking, perhaps isomorphic to each other. One comes rom a live conversation while the other comes via an alerting system, which may represent the two systems.
# On the other hand, perhaps the identifier system evolved over time and any given human only has an identifier from one system or the other. Assuming all numbers and letters are usable and each identifier could have only a letter or number in that place, the first identifier represents a space with at least 10*10*26*26*10*10*26*26*100=457 billion entries, while the space of the second is 10*10*10*10*10*26*10*26*10*10=68 billion. Perhaps, like IP addresses evolving from IPV4 to IPV6 because of the fear of exhaustion, the alien tracking systems similarly changed. This would imply the second (YouTube-posting) human is older than the first (cellphone carrying).

The identifier for the one buying the phone begins with "Human 38XT11". This seems likely to be a reference to {{w|THX 1138}}. This was the title of {{w|George Lucas}}' first film, which is also {{w|THX_1138#Etymology_and_references|referenced}} in the original {{w|Star Wars (film)|Star Wars}} film. The name contains the number in reverse as well as the letters if human could be written as H.

==Transcript==
:[Three aliens are looking at a screen. They each have six tentacles, of which four are used as legs, and the other two can be used as arms. They also have a small mouth and two eye stalks with a large eye at the end of each. The eyes has large eyelashes all the way around. One of the aliens is standing to the left of the screen, indicating it by raising one of its tentacles. The other two aliens stand to the right of the screen looking at the picture. The screen's image depicts a cross-sectional diagram showing two humans in a rough landscape. There is a shaded area above each of the humans and the terrain. The shaded area's boundary consists of arcs of differing sizes centered upon each human. To the left of the first human there is also a small straight area over the ground. To the left of this towards the edge of the screen, what appears to be an arc with a very large radius that begins and rises high up compared to the other two arcs, around a point beyond the on-screen image's edge. The rightmost human's zone has a dashed region between concentric radii of different sizes indicating that this zone has been revised further out than before. Four flying-saucer like spaceships are shown in the air close to, but above, the shaded areas. One high near the left curve, one over the flat area, one near the intersection between the two small arcs and one over the middle of the right arc.]
:Left Alien: Human 38XT11-B-C54  just bought a new phone with a 10x zoom, so we have to expand our restricted flight zone by 1,800 meters to keep our ship blurry.
:Right Alien: Seriously? Didn't they '''''just''''' upgrade?
:Left Alien: I know, I know...

:[Caption below the panel:]
:The hardest part of being an alien observing Earth is keeping track of what cameras everyone has.

{{comic discussion}}

[[Category:Aliens]]
[[Category:Comics referencing THX 1138]]

2532: Censored Vaccine Card

2022-01-25T16:50:00Z

172.68.50.237: +Category:Comics referencing THX 1138 (someone should create the category, I can't because I'm not able to recover my account pwd)

{{comic
| number = 2532
| date = October 22, 2021
| title = Censored Vaccine Card
| image = censored_vaccine_card.png
| titletext = CVS's pharmacies are fine, but I much prefer their [censored]s.
}}

==Explanation==
This comic is another entry in a [[:Category:COVID-19|series of comics]] related to the {{w|COVID-19 pandemic}} of the {{w|SARS-CoV-2}} virus, which causes {{w|COVID-19}}, specifically regarding the [[:Category:COVID-19 vaccine|COVID-19 vaccine]].

The comic hinges on the sharing of vaccination card photos on social media as proof that the user has been vaccinated against COVID-19 (in this case, gotten a {{w|Booster dose|booster shot}}, a third dose of the vaccine). When people in the United States first started receiving their vaccine shots, a large number of them shared photos of the CDC vaccination proof cards that they received alongside the vaccines; it was enough of a trend that the {{w|Federal Trade Commission|FTC}} released an official statement warning vaccine recipients [https://www.consumer.ftc.gov/blog/2021/02/social-media-no-place-covid-19-vaccination-cards not to share photos], due to the cards containing {{w|Personal data|personal identification}} that probably should not be made public.

The irony here is that [[Randall]] has "{{w|Sanitization (classified information)|censored}}" (redacted) some impersonal lines, such as the instructions that are identical on all vaccination cards, and many easy-to-guess lines, while not censoring any of said personal information.
Considering the date of the 3rd dose (one day prior to the comic's uploading), it is likely that the blackouts in the last line are only covering whitespace.

Another possible reference here is to the practice of filing for {{w|Freedom of Information Act (United States)|FOIA}} requests that has been getting more popular in recent years, with sites like muckrock.com developing to support it. These requests provide for citizens to view the contents of government files, but the files first go through a process of redaction via solid black rectangles. The information that is redacted can seem random, ridiculous, and frustrating, and be a source of legal action.

The caption indicates that his intention is to "seem more mysterious". This is best exemplified by the blanking of most of the word "clinician" to leave the acronym "{{w|Central Intelligence Agency|CIA}}", referring to the US government agency known for its frequently "mysterious" (classified) activity, as well as its liberal use of redaction like that in the comic.

[[File:CDC_COVID-19_Vaccination_Record_Card.jpg|thumb|300px|A real and appropriately censored CDC vaccination record.]]

The "19" in COVID-19 is systematically censored in the comic. This is humorous because currently COVID-19 is the only thing that could be meant by "COVID-[anything]", and so the redaction is pointless. This may also be intended, in the interest of mystery, to imply some future outbreak of a similar disease (given an identifier based on the year of its inception).

The sentence at the top of the card, which appears once in English and once in Spanish, has equivalent portions redacted in both languages:
* "medical information" and "the vaccines you have received" in the English version, and
* "información médica" and "las vacunas que ha recibido" in the Spanish.
This is the first comic including a sentence (or, given the censorship, at least a good portion of one) in Spanish.

{{w|CVS Pharmacy}} is a pharmacy chain in the US which provides COVID-19 vaccinations. CVS #05309 is in Pineville, LA, while Randall lives in Massachusetts; it is not clear why he would have received his first vaccine dose in Louisiana.

The title text comments on the "Provider or clinic site" of the second dose on the card. Where the word "pharmacy" appears in the previous row (and would be on a real card), it is censored in the comic. The most reasonable assumption is that the word is still "pharmacy" and that Randall has simply chosen to redact that instance for some reason, but the title text humorously implies that it was in fact some ''other'' CVS-related venture where he got his second dose, for instance a "CVS parking lot" or perhaps an {{w|anti-submarine warfare carrier}}.

CVS's parent company, {{w|CVS Health}}, does have other enterprises with compatible names: {{w|CVS Caremark}} and {{w|CVS Health#CVS Specialty|CVS Specialty}}. However, neither of these provide COVID-19 vaccinations.

===Numerical trivia===
Randall's patient number is the 2nd to 9th digits of the fractional part of the decimal expansion of {{w|pi}} inclusively: 41592653.

The lot numbers of the first and second doses allude to two numbers that appear frequently in Star Wars and other works related to George Lucas: {{w|THX 1138#Etymology and references|1138}}, and {{w|21-87#Influence on George Lucas|2187}}. The lot number of the third dose is the {{w|1729 (number)|Ramanujan-Hardy number}}.

The Clinician number for the first shot is the last 4 digits of the phone number for {{w|867-5309/Jenny|"Jenny" 867-5309}}, which has been entered into communication technology by a massive number of people.

Given the reasonable assumption{{citation needed}} that the partially censored year relates to the twentieth century, the date of birth on the card corresponds to that given in the acknowledged [[Randall_Munroe#Timeline|timeline]] for Randall. The censorship of that specific part of his date of birth might be related to the fact that the number "19" has been systematically redacted on the card. Another interpretation is that Randall is implying he is either over one hundred years old or a time traveler, although neither is likely to be true.{{citation needed}}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Profile picture of a Cueball's head and shoulders, with unreadable lines of text to the right.]
:Check it out, I just got my booster!

:[Picture of the U.S. COVID-19 Vaccination Record Card attached on a media post. The card includes pre-printed information in black and handwritten information in blue, the latter indicated here by bold text. Some of the text has been blacked out, indicated here by "[censored]".]

:COVID-[censored] Vaccination record card
:[At the upper right of the card appears the logo of the U.S. Department of Health and Human Services, a stylized eagle surrounded by the words "Department of Health & Human Services USA", although those words are not legible in this drawing. Next to that appears the logo of the Centers for Disease Control and Prevention, a shaded box with the letters "CDC" and the words "Centers for Disease Control and [censored]" below it.]

:Please keep this record card, which includes [censored]
:about [censored].
:Por favor, guarde esta tarjeta de registro, que incluye [censored]
:[censored] sobre [censored].

:'''Munroe''' '''Randall'''
----
:Last Name First Name

:'''10-17-[censored]84''' '''41592653'''
----
:Date of birth Patient number

:[A table fills the remainder of the card. It has four columns and five rows. The first row gives the column names:]
:Vaccine. Manufacturer lot number. Date. Provider or clinic site.
:[The rest of the rows have been filled out. Each "date" cell also includes pre-printed "MM DD YY" below the line where the date is written.]
:1st dose COVID-[censored]. '''Pfizer ER1138'''. '''04'''/'''01'''/'''21'''. '''CVS Pharmacy Clinician #5309'''.
:2nd dose COVID-[censored]. '''Pfizer ES2187'''. '''04'''/'''22'''/'''21'''. '''CVS''' [censored] [censored].
:Other. <sup>'''3rd dose'''</sup> [censored] '''FH1729'''. '''10'''/'''21'''/'''21'''. [censored] [censored] [censored]'''CIA'''[censored].
:Other. [censored]. [censored]/[censored]/[censored]. [censored].

:[Caption below panel:]
:Security tip: To seem more mysterious, try censoring only ''non''-identifying information.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:COVID-19]]
[[Category:COVID-19 vaccine]]
[[Category:Comics featuring Randall Munroe]]
[[Category:Comics referencing THX 1138]]

Talk:2568: Spinthariscope

2022-01-15T01:01:28Z

172.68.50.237:

Someone has already updated the Wikipedia page to mention this comic reference, before anyone here has gotten around to writing the explanation [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 19:56, 14 January 2022 (UTC)

I added an initial explanation, but I don't recognize the references to gallium and tritium (although I know what glowsticks are), so someone else should fill in about that. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 20:13, 14 January 2022 (UTC)

Seems like there's something off with how the "ratio" is worded. It is a safe and legal toy, so the "actual safety and legality" is actually high-ish, right? [[Special:Contributions/172.70.178.25|172.70.178.25]] 20:44, 14 January 2022 (UTC)

- If "actual safety" is a large number and "apparent safety" is a small number, then their ratio (actual divided by apparent) is a large number. If "sctual safety" is a small number and "apparent safety" is a large number, then their ratio is a small number. So the comic's wording is perfectly fine and logical, and the paragraph about products in the explanation is not needed. (It's also kind of, um, **untrue**, but I'm trying to be kind to whoever wrote it.) [[Special:Contributions/172.70.114.99|172.70.114.99]] 21:44, 14 January 2022 (UTC)

:If you take the amount of screaming in terror (high for the spin-thingie) and DIVIDE by the actual danger (low for the spin-thingie), then you get a ratio that in a rational world would always be close to 1 - the worse something is, the more (rational) people would want it banned. I think his point is that the ho-hum factor, the LACK of protests, for throwing a sharp heavy object high in the air toward a group of other children, divided by the actual danger from said sharp heavy object thrown high toward other children, results in a value on the opposite end of the spectrum. I was one of the kids who threw these things around without thinking, and nobody ever objected. Fortunately, I never saw any kid get killed by them, but that was pure luck. Point being, I don’t think the wording in the comic is wrong; the ‘correction’ is.[[Special:Contributions/108.162.245.103|108.162.245.103]] 22:35, 14 January 2022 (UTC)

::On second thought, there is something confusing about the wording of the comic: it conflates safety and legality as if they were the same thing, but the fact that they are NOT the same is the problem.[[Special:Contributions/108.162.245.223|108.162.245.223]] 22:49, 14 January 2022 (UTC)
:::They're not the same, but they're correlated. While the government hasn't always been very dilligent about it, these days dangerous toys usually get banned. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 22:57, 14 January 2022 (UTC)

::But the comic don’t divide the large/low amount of screaming by the low/large amount of danger, but by the large/low amount of safety for spinthariscope/darts. Hence the formula of the comic results in a number close to 1 for both toys, and a regular toy (low amount of screaming divided by large amount of safety) results in a number closer to zero.
::[[User:While False|While False]] ([[User talk:While False|talk]]) 22:57, 14 January 2022 (UTC)

:::You’re right. The comic is misworded, but not by saying “ratio” instead of “product” - it’s misworded by saying “actual safety” when it means “actual danger” thus giving the ratio a backward meaning.[[Special:Contributions/108.162.245.77|108.162.245.77]] 23:17, 14 January 2022 (UTC)

::::Just so!
::::[[User:While False|While False]] ([[User talk:While False|talk]]) 23:28, 14 January 2022 (UTC)

:I believe the ratio is apparent danger vs actual danger. So spinthariscope would be 10 apparent danger / 1 actual danger. And the lawn darts would be the opposite end of the spectrum: 1 apparent danger / 10 actual danger. [[Special:Contributions/172.70.214.185|172.70.214.185]] 22:40, 14 January 2022 (UTC)

:To me it appears that you are describing the “perceived danger to actual danger” ratio, while the comic mentions the “perceived danger to actual safety” ratio, which would be of no extreme value (high number divided by high number) for a spinthariscope. So I think that the current explanation, while cumbersome and against the convention of use of ratios, is mathematically true.
:[[User:While False|While False]] ([[User talk:While False|talk]]) 22:57, 14 January 2022 (UTC)

Make your own Spinthariscope kiddies https://www.instructables.com/Pocket-Size-Spinthariscope/. [[User:Steve|Steve]] ([[User talk:Steve|talk]]) 21:05, 14 January 2022 (UTC)

The {{w|Gilbert U-238 Atomic Energy Laboratory}}, which was marketed in the early 1950s & contains more energetic radioactive sources (i.e. uranium ores), might possibly be more dangerous. [[Special:Contributions/172.70.143.22|172.70.143.22]] 21:28, 14 January 2022 (UTC)

{{w|Talk:Spinthariscope|The talk page for the Wikipedia article}} has an interesting exposition by an IP in 2010 of why these aren't dangerous and the various isotopes used. [[User:Yngvadottir|Yngvadottir]] ([[User talk:Yngvadottir|talk]]) 21:49, 14 January 2022 (UTC)

And with that simple strip, all existing spinthariscopes sold out. [[Special:Contributions/172.68.50.237|172.68.50.237]] 01:01, 15 January 2022 (UTC)