explain xkcd - User contributions [en]

697: Tensile vs. Shear Strength

2022-12-20T09:10:25Z

172.68.50.17: /* Explanation */

{{comic
| number = 697
| date = February 3, 2010
| title = Tensile vs. Shear Strength
| image = tensile_vs_shear_strength.png
| titletext = Although really, the damage was done when the party planners took the hole punch to the elevator ribbon to hang up the sign.
}}

==Explanation==
Tensile strength represents how hard you can pull on something without it breaking. Shear strength represents how hard you can try to cut it without it breaking. Many materials have great tensile strength but low shear strength (such as dental floss — try to break it by just pulling on two ends), including whatever this space elevator is made of. The material clearly has extremely high tensile strength because it can hold the elevator in place, with one end on the ground and one in space, but it can be cut with a simple pair of pruning shears. This also highlights the fact that "shear strength" and "shears" are [https://www.etymonline.com/word/shear etymologically related].

A {{w|space elevator}} is a proposed construction that would make space travel easier. It consists of a long string attached to the Earth (near equator) on one end and a counterweight (beyond the {{w|geostationary orbit}}) on the other end, kept taut and in one place by the gravity and centrifugal forces. This would make it possible to carry spacecraft into the orbit by simple mechanical means, as opposed to requiring the use of rockets as is the case nowadays, saving a lot of energy and resources.

The phrase "a modern Babel" refers to the biblical story of the {{w|Tower of Babel}} (later referenced in [[2421: Tower of Babel]]), in which humans endeavor to build a tower reaching heaven. Their arrogance angers God and prompts him to sabotage the project. A space elevator can be seen as a modern equivalent of a tower to heaven.{{citation needed}} Additionally, the expression "a modern Babel" may be used figuratively to describe huge projects (especially buildings or human-made structures) that fail because they are too ambitious.

The title text makes the point that even before [[Black Hat]] cut the space elevator's ribbon-like cable in two, it was ruined by the holes in it for the banner. The holes would reduce the surface area of the cross section of the ribbon, reducing its ability to keep the elevator attached to the ground. The flag and holes would also potentially make it impossible for the elevator to travel up the ribbon, making the entire elevator useless.

==Transcript==
:[A space elevator occupies the height of the frame, consisting of a base, a cable extending out into space, and an elevator unit with standard elevator features such as sliding doors and up/down buttons. A banner flutters in the breeze attached to the cable going up above the elevator. There is text on the banner. Text appear in four lines split across the elevator cable itself, the rhyming portions of the text is on the right side of the cable. Five individuals stand at the base of the elevator. To the left are Megan, a Cueball-like guy with his arms raised, and Ponytail, who is holding a bottle of champagne/sparkling wine which is bubbling out down the neck of the bottle. To the right is Black Hat, who cuts the cable with a pruning shear like it was part of the ceremony as a ribbon cutting. Finally further right is Cueball who sees what Black Hat is doing. He is very alarmed holding a hand to his mouth while holding the other out towards Black Hat.]

:Banner: Space Elevator
:Banner: Grand opening
::{|
|-
|style="text-align:right;"|After countless
|style="text-align:left;"|engineers
|-
|style="text-align:right;"|spend trillions over
|style="text-align:left;"|fifty years,
|-
|style="text-align:right;"|a modern babel
|style="text-align:left;"|disappears
|-
|style="text-align:right;"|because some fuck brought
|style="text-align:left;"|pruning shears.
|}
:Pruning shears: ''Snip''
:Cueball: ''!!''

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Multiple Cueballs]]
[[Category:Elevators]]
[[Category:Space]]
[[Category:Science]]
[[Category:Sabotage]]

Talk:2052: Stanislav Petrov Day

2022-09-27T08:17:53Z

172.68.50.17:

Wednesday was also Talk Like a Pirate Day [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:51, 28 September 2018 (UTC)
: What is a pirate's favorite letter?
: Aaaar!
: Many people think it's the 'R', but it's actually the 'C'! [[Special:Contributions/162.158.106.168|162.158.106.168]] 15:05, 28 September 2018 (UTC)
::...I feel like I've read that on a webcomic somewhere... [[Special:Contributions/172.68.174.16|172.68.174.16]] 15:32, 28 September 2018 (UTC)
:::It's a common audience participation joke when Paul and Storm perform The Captain's Wife's Lament, maybe that's what you're thinking of [[Special:Contributions/162.158.62.123|162.158.62.123]] 13:36, 1 October 2018 (UTC)
:::Ye'd think they'd be the most fond if the 'C', but without 'P', they just be irate. [[Special:Contributions/108.162.241.100|108.162.241.100]] 16:01, 28 September 2018 (UTC)
Ayyy, got this one pretty fast. [[Special:Contributions/162.158.154.13|162.158.154.13]] 15:18, 28 September 2018 (UTC)
:I thought that International Talk Like A Pirate Day was September 19th. I've been celebrating it on that day for decades [[User:Mr. I|Mr. I]] ([[User talk:Mr. I|talk]]) 19:37, 29 September 2018 (UTC)

I just read about Mr Petrov the other day, maybe on Quora. I wonder if Randall received the same article in his daily digest :) [[Special:Contributions/141.101.107.78|141.101.107.78]] 16:26, 28 September 2018 (UTC)

'''History of Petrov Day as a holiday'''

My critics: Not explaining much to the comics content; even admires that a stupid citation is still needed; this Wiki isn't a link list; I can do more... But I don't want to do censorship so maybe we can put this into a single sentence belonging to an explanation. Otherwise some could be moved to a trivia section. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:17, 28 September 2018 (UTC)

I can't find anything specific, but a couple other articles list this BBC link https://www.bbc.com/news/world-europe-24280831 which states that his heroism was kept secret until after the collapse of the Soviet Union (1991ish) and that Mr. Petrov "kept silent for 10 years" - so 1993 or maybe 2001. [[User:Afbach|Afbach]] ([[User talk:Afbach|talk]])
:Read the first paragraph: "The incident was unknown to the public until it was revealed shortly before the dissolution of the Soviet Union in 1991." --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:41, 29 September 2018 (UTC)

I think everyone missed the subtle point in this comic - Stanislav was famous for correctly identifying the nuclear attack alert as a false alarm, and Cueball thought the calendar alert he received was a false alarm as well! I believe that's the real joke here! [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 14:30, 29 September 2018 (UTC)
:I agree. Had already just added this when I read your comment --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 22:34, 30 January 2020 (UTC)

You all missed the joke of the “false alarm clock”, which is that if it keeps going off when it’s not supposed to, you very well might assume that it’s another false alarm when you are actually supposed to wake up, and thus will sleep late anyway, completely defeating the point of the alarm. [[User:PotatoGod|PotatoGod]] ([[User talk:PotatoGod|talk]]) 20:33, 29 September 2018 (UTC)
:I agree. Have just added this after I read your comment --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 22:34, 30 January 2020 (UTC)

Is it just me, or does Eliezer Yudkowsky show up abnormally frequently in explainXKCD? [[Special:Contributions/108.162.241.118|108.162.241.118]] 04:35, 30 September 2018 (UTC)

So, corrolarily if that's a word, if you ''don't'' ignore the alarm clock and go back to sleep, the world ends?
(On a personal note, Stanislav Petrov day is the day before my birthday. It is somewhat gutting to think back on a day when I was opening presents, stuffing myself with cake, and running around the yard playing hide & seek with a bunch of other kids, and thinking just how different that day might have been).
[[Special:Contributions/172.68.59.30|172.68.59.30]] 17:45, 1 October 2018 (UTC)

Hmmm, at first I thought this incident may have been the inspiration for the movie "WarGames", but then hearing that it was kept secret until over a decade later, means that couldn't have been the case. Or could it? -Electro-- [[Special:Contributions/172.69.68.231|172.69.68.231]] 21:59, 7 October 2018 (UTC)

Also, note the subtle choice of exclamation "Oh, shoot!" which would have been the response of Petrov's superiors if he had not chosen to ignore the alarm and done as he was directed.[[Special:Contributions/162.158.2.172|162.158.2.172]] 02:01, 26 November 2018 (UTC)
:Nice spotted. Have just added this after I read your comment --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 22:34, 30 January 2020 (UTC)

'''NASA's DART mission'''

I can't help pointing out that on 2022 Stanislav Petrov Day the DART probe hit the tiny asteroid moon Dimorphos in a mission to test how to redirect a potential future Earth-threatening asteroid. Looks like APL wanted to take part in the world-saving fame...

Talk:2666: Universe Price Tiers

2022-09-02T19:43:18Z

172.68.50.17: 6

We seem to be in Universe Standard, based on the cosmic speed limit
[[User:Victor|Victor]] ([[User talk:Victor|talk]]) 22:03, 31 August 2022 (UTC)

Is the price per user (human)? Or payed by the "god" who runs the universe?
The interpretation would change quite a bit. If per user, some could travel fast while others would not see ads and could even be immortal.
If per universe, would the concept of ads disappear?
[[User:Victor|Victor]] ([[User talk:Victor|talk]]) 22:25, 31 August 2022 (UTC)
::The tree sound can't be a particular human's experience, and the speed limit seems intended to be per universe.

General comment, I think each line of the table should have a separate one-line or one-paragraph explanation, rather than squishing it into one column of a table which mostly reproduces the comic text. i.e. we don't need the table in the explanation, although it works fine in the transcript imo. [[Special:Contributions/172.69.62.71|172.69.62.71]] 23:40, 31 August 2022 (UTC)edit: a word

"Yes, and he cheats" may be a reference to a quote from ''Sid Meier's Alpha Centauri''.
::I fully expected something like ''"Most gods throw dice, but Fate plays chess, and you don't find out 'til too late that he's been playing with two queens all along."'' (from ''Interesting Times'' by Terry Pratchett) [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 01:47, 1 September 2022 (UTC)
::The SMAC quote is "Einstein would turn over in his grave. Not only does God play dice, the dice are loaded. - Chairman Sheng-ji Yang", from the Probability Mechanics tech. Also, the "God does not play dice" quote is stated during the Supercollider secret project movie. I doubt the comic is referencing any particular media here, though. [[Special:Contributions/172.69.22.5|172.69.22.5]] 02:40, 1 September 2022 (UTC)
::Meanwhile, Stephen Hawking said "Not only does God play dice, but... he sometimes throws them where they cannot be seen." -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 16:01, 1 September 2022 (UTC)

Under ''Number of angels that can dance on the head of a pin'', '64' is 2⁵ and may be making reference to the Nintendo 64 game system. [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]]) 01:54, 1 September 2022 (UTC)
::And just for the record, 4096 is 2¹². [[User:RAGBRAIvet|RAGBRAIvet]] ([[User talk:RAGBRAIvet|talk]])
:::64 = 2<sup>6</sup> != 2<sup>5</sup> = 32. [[Special:Contributions/172.68.50.17|172.68.50.17]] 19:43, 2 September 2022 (UTC)
:: Note that the philosophical question of how many angels can dance on the head of a pin turns to have much more useful meaning if we realize that the question wasn't if 64 or 4096, but if it's a finite or infinite number, that is, if angels are subject to {{w|Pauli's exclusion principle}}. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 15:59, 1 September 2022 (UTC)

::: I think the answer is [https://www.imdb.com/title/tt8071704/characters/nm0000531 to be found elsewhere]. And it is a different power of 2! [[Special:Contributions/172.70.162.147|172.70.162.147]] 17:26, 1 September 2022 (UTC)

Who is paying our subscription? How do we ensure we don't get demoted to lite?

Here, the sound of one hand clapping is pretty much "toop." Put your hand out flat fingers together, and no thumb involved, quickly make a fist. Toop. Edit I'm not making a fist. Im keeping the last joints straight and smacking my hand[[Special:Contributions/172.70.134.95|172.70.134.95]] 15:59, 1 September 2022 (UTC)
:But two hands each doing that (or slapping another bit of body) aren't "two hands clapping", but more like two hands ''clasping''/something-or-other-like-that.
:If you could bring your one hand to a sudden stop in mid-air ''as if'' hitting another hand, it might be closer, but there's no sudden stop possible like a contact-stop. Plus a full-fledged clap for maximum ovational volume involves cupped hands trapping a resonant volume of air between them, almost sealed (wet hands so positioned can be used to force a squeaky-fart sound out from between them), and neither an "air clap" or the toop-clasp can do anything so dramatic with a solo hand. [[Special:Contributions/141.101.99.154|141.101.99.154]] 17:54, 1 September 2022 (UTC)
: the sound can be more clap like if you bend your hand upwards and keep it like that. Then loosen your fingers, and smash your upward lower arm to the front and back. My one armed brother taught me. It's handy (hehe) if one hand is holding a drink. [[Special:Contributions/172.68.51.204|172.68.51.204]] 07:36, 2 September 2022 (UTC)

I have a problem with the "Bad things..." portion. ''If'' I was a bad person, then I would never pay for the universe, as I would be better off in the free version, where nothing bad would ever happen to me. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 19:17, 1 September 2022 (UTC)

The "bad things" section is a bit bothersome: good things don't exist without bad things. Without bad things, good things are just...things. So maybe awareness of bad things is still extant in UniPro? That way, good things would still be at the upper end of a theoretical scale.

But the subjectivity of badness is concerning in a bad-things-don't-happen realm. I reckon plenty of people who could spring for fifty bucks a month would list rum, Katharine Hepburn movies, gay people and Jews as bad things that therefore won't happen. If I stump up my Pro subscription, do I have to share the universe with these douchebags, or do we each get our own? And if it's the latter, how much of a douche must you be to be excluded from my universe? Can we differ a little and still coexist, or do we have to gel perfectly? And how would that ever happen...and would it be tolerable to live surrounded by my opinion-clones? Is this...is this the too-perfect Matrix v.1.0? Am I buying a ticket to a simulated utopia while my body atrophies?
You monster! Guards! Guards! Let me out.....

[[Special:Contributions/172.71.178.35|172.71.178.35]] 23:09, 1 September 2022 (UTC)
Note that Universe Lite is marked as trademark, Universe Standard as a registered trademark, and Universe Pro as...BOTH. This is a joke; more is better, esp. in lists of features. But there's no point in claiming a mark is both a trademark and a registered trademark.

How to clap with one hand: https://www.youtube.com/watch?v=qwoq3QBaQAY [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 04:38, 2 September 2022 (UTC)

If a tree falls in a forest and there's no one there to hear it, then there is NO SOUND. The act of the tree falling will create vibrations in the air, but those vibrations only become 'sound' when they impact on a tympanic membrane (such as an eardrum) that is connected to a brain. Sound happens in your head, folks. Of course, in practice, the likelihood of a tree falling in an area that contains NO tympanic membranes at all is impossible given the abundance of miniature scaled life on Earth. That said, we have no idea whether insects actually perceive those air vibrations as 'sound' in the same way that humans do - the fairy fly, for example, is so small that it can 'swim' through air rather than flying, so probably perceives sound waves the same way that humans experience ocean waves.
<-----Pish-Posh. Sound happens regardless of aby tympanic membranes. Sound: noun 1. vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear. The definition is CAN be heard, not ARE heard. Sound vibrations cause MANY things to happen besides vibrating tympanic membranes, and it's STILL SOUND.[[Special:Contributions/172.70.100.60|172.70.100.60]] 11:47, 2 September 2022 (UTC)

[[User:MarquisOfCarrabass|MarquisOfCarrabass]] ([[User talk:MarquisOfCarrabass|talk]]) 05:50, 2 September 2022 (UTC)

We should do a comparison of universe standard vs our universe see if that's what we're doing [[User:Mushrooms|Mushrooms]] ([[User talk:Mushrooms|talk]]) 08:13, 2 September 2022 (UTC)
:...hang on, I already downloaded a crack to repatch the executables to get around the pesky copy protection/licence-key manager. The patcher utility says it might take some time, and I've had to give it superuser access to the entire system for some reason, so it might be a good idea to save your current session and let it do its job before messing about in the menus or we might find unexpected results! [[Special:Contributions/172.70.85.5|172.70.85.5]] 11:01, 2 September 2022 (UTC)
:I looked in the leaked payment notes, and found that biblicalGod31, the current payer, refused to pay 2 geomagnetic reversals ago, so our subscription got demoted to standard. Looking in the End God License Agreement, it seems that next geomagnetic reversal we will be demoted to lite. (Sorry if I didn't do humor well). [[Special:Contributions/172.70.126.11|172.70.126.11]] 13:38, 2 September 2022 (UTC)
::I definitely want to see this movie/read this book now. Our heroes discover that the universe is in fact a simulation. Not a malevolent one like The Matrix, but a for-fun one like implied by this comic. The heroes come to realize that the entity playing the simulation is about to screw it up somehow (possibly by not paying the subscription fee), and they have to figure out how to break out of the simulation and convince the apathetic entity to care about the inhabitants of the universe and save it from annihilation or demotion to the free tier. [[Special:Contributions/172.70.178.65|172.70.178.65]] 15:01, 2 September 2022 (UTC)

Talk:2666: Universe Price Tiers

2022-09-01T08:06:59Z

172.68.50.17:

2656: Scientific Field Prefixes

2022-08-09T06:40:24Z

172.68.50.17: /* Explanation */

{{comic
| number = 2656
| date = August 8, 2022
| title = Scientific Field Prefixes
| image = scientific_field_prefixes.png
| titletext = Massage: Theoretical (10), Quantum (6), High-energy (2), Computational (1), Marine (1), Astro- (None)
}}

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

Google Scholar allows searches for both an unquoted and quoted string (e.g. [https://scholar.google.com/scholar?hl=en&as_sdt=0%252C5&q=marine+dentistry marine dentistry] vs [https://scholar.google.com/scholar?hl=en&as_sdt=0%252C5&q=%22marine+dentistry%22 "marine dentistry"]). In the former case only entries with those exact words in that order will be returned (ignoring capitalization and punctuation marks), in the latter any entry with both of those words somewhere. While this gave opportunities for the humorous point it was not the ideal strategy for actually finding relevant articles. For example the less limited [https://scholar.google.com/scholar?hl=en&as_sdt=0%252C5&q=marine+dentistry marine dentistry] search gave over 100 k results, ranging from a book chapter on [https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119545804.ch11 marine mammal dentisty] by way of dental procedures on Marine Corps personnel to uses of the "marine polymer chitosan" in dentistry. And the search for [https://scholar.google.com/scholar?hl=en&as_sdt=0%252C5&q=high-energy+theology high-energy theology] give over 15000 entries. Admittedly, most of those only use "high energy" as a generic reinforcement term, but the book "[https://books.google.se/books?hl=en&lr=&id=34YHCAAAQBAJ&oi=fnd&pg=PA1&dq=high-energy+theology&ots=tI3TtCfBPK&sig=YmnqNK3IXV8sqDtt44tE877cm7k&redir_esc=y#v=onepage&q=high-energy%20theology&f=false Cosmology, History, and Theology]" actually looks like it could be pertinent to the topic. There is even a paper titled [https://www.proquest.com/openview/8446d9a14d81424f1dfd09615852b5f5/1?pq-origsite=gscholar&cbl=1819044 " Battlestar Gallactica" and Mormon Theology] which I, in the name of preserving my few remaining SAN points, will not attempt to obtain.

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

{{comic discussion}}
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