explain xkcd - User contributions [en]

Talk:3039: Human Altitude

2025-01-21T06:45:22Z

172.70.207.140: mir

I splurged a few paragraphs to try to deal with each detail (and a few things not ''directly'' obvious, but related). However, it's a mess and here (UK) it's basically past my bedtime and I have an early(ish) start tomorrow so... I know that if I had spent another half hour on it, it would have been tighter (less florid?), and would be linking to Yuri Gagarin, Montgolfier, Hubble, man-capable chinese kites, the likes of George Cayley, etc. And I never actually ''mentioned'' the Title Text, though the last paragraph I put is sort of relevent so might just need an "In the title text, it says ..., and, as it happens, ...". I shall leave it up to the editing-gods as to whether my sacrifice is acceptable or entirely in vain... Such is life! And so, goodnight. [[Special:Contributions/172.68.205.119|172.68.205.119]] 01:39, 18 January 2025 (UTC)
:I linked up a couple Wikipedia articles with [[Template:w]] and wish I could add all of those things, but alas: today’s the last day of the semester on a 3 day weekend here in the States and I’ve been sick all week. I’m going to be going now to work on my missing assignments and hopefully finish them, really wish that we can finish up the explanation as quick as we usually do! '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 01:48, 18 January 2025 (UTC)
It seems strange how jagged this is and how low the lows are. Since roughly 1930 (certainly since 1940 at the very latest) someone, somewhere in the world has been flying in an airplane, at a minimum of probably 4.5km for the lowest person. And since like 1955 there's always at least someone over like 7km roughly, and since the jet age like 10km+. This isn't the kind of carelessness that xkcd is known for, unless I'm missing something.[[User:Kchinger|Kchinger]] ([[User talk:Kchinger|talk]]) 03:27, 18 January 2025 (UTC)kchinger
:The Apollo part of the graph implies an at least weekly, probably daily or finer resolution. Aviation unlikely reached 4.5 km above surface on a daily basis until transpacific high altitude airliners became a regularity well after WW2. Planes of the 1930s could achieve greater heights, but usually only attempted when moutains forced them to (so it was not height above ground) and high altitude Zeppelin bombers of WW1 did not fly on a daily basis, sometimes leaving week long gaps between campaigns. However, the pre-airplane lows are still wrong: Pole vaulting has been documented since ancient egypts for crossing of crevices, bodies of water, etc. giving a guaranteed minimum of 2-3 meters. Cliff jumping in the 10s of meters range is also likely to have occured daily somewhere on the globe long before the 20th century and I would not be surprised if some tyrannt created a phase of more than 100 m daily by intensive cliff throwing. (As with the ancient chineses kite observation flights, it might be interesting to extend this graph well into the past, at least up to Spartan postnatal parenthood planning.) [[Special:Contributions/172.70.250.194|172.70.250.194]] 16:06, 18 January 2025 (UTC)
::''Aviation unlikely reached 4.5 km above surface on a daily basis until transpacific high altitude airliners became a regularity well after WW2. Planes of the 1930s could achieve greater heights, but usually only attempted when moutains forced them to...'' The limit is the humans. Past 10k or 15k feet (~4.5km) they go loopy then pass out. Pressurized cabins are costly. Wiley Post flew past 17,000 ft (to 50kft!) in 1934 with a pot on his head, after two other suits split their seams. War forces high flight: the B-17 crews had oxygen bottles and electric heat suits; they did fly about every day but thin air was the least of their problems. B-25 was pressurized but not nice inside. The Constellation (the world's finest tri-motor) was one of the first shirtsleeve cabins, to 24,000 ft (7,300m), but was a very premium ride. The DC-2, DC-3, and DC-4 were unpressurized (a few test DC-4s tried it). Piston engine output tends to zero by 55k ft, even with supercharger. The real move to high altitude comes with turbojets (Comet is credited with first pressurized production passenger plane), Boeing 707, Caravelle, DC8, etc which often work better far above 20k feet. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 20:09, 18 January 2025 (UTC)
:::While pesky waterbags limit the altitude of passenger aircraft, military, scientific and perhaps even postal/fright aviation went past 4.5 km without pressurized cabins. As mentioned, London was bombed at the end of WW1 from Zeppelins with regular service ceilings well above 6 km, the record was set at 7.3 km. And these did not even carry oxygen for the full flight time, as did record attempts. Take a link to the first flights above Everest in the early 30s: https://rarehistoricalphotos.com/first-flight-expedition-everest-1933/ However, this is all record/rare stuff for top peaks. With overlapping nights in Europa and America, the global low of the 30s was probably limited by some BOAC cruisers flying 500 to 1.000 m above the sea or some valley floor in southeast Asia. [[Special:Contributions/172.71.148.59|172.71.148.59]] 22:19, 20 January 2025 (UTC)

For the "Apollo bits", I actually have (fairly) precise data, but the question is whether the spiky bits resemble the reality at all. Here's a version with accurately positioned timestamps, but with the the altitude normalised. Launch is at bottom, time in lunar orbit is at top. To keep the data short I have removed the 'oscillation in orbit" of them all (except for 13, which ''just'' looped around and came straight back out again), and the track of the landers (as never really gets any ''further'' away, averaged over a lunar orbiter orbit) as these things aren't really isn't visible if overviewing the whole program. Blue=orbit-only, Green=orbit-with-landing, Magenta is 13's mission. All sat on a month-start scale (thicker lines are year-starts), for reference.
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{{cob}}
If you want to see it, copy the text into a file, save/rename as a .svg and open it in any modern browser. (There are other ways of opening SVGs, but that's probably the easiest way for most of those who don't have a preference.) ...to make it look more like the comic, I suggest you make the stroke-width for the missionLines group '''''huuuuuuge!!!!''''' ;) [[Special:Contributions/162.158.74.118|162.158.74.118]] 21:14, 18 January 2025 (UTC)

Some of the text (both in the explanation and the "into snow or water" in the title text) seems to suggest a "who wasn't shortly killed" that isn't stated in the chart. [[Special:Contributions/172.69.246.150|172.69.246.150]] 05:55, 18 January 2025 (UTC)

:"into snow or water" is in the title text which is about surviving... --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 13:05, 18 January 2025 (UTC)

I wonder why the chart does not consider parachutes? They might have been available around the same time as balloons, maybe earlier? [[User:Captain Nemo|Captain Nemo]] ([[User talk:Captain Nemo|talk]]) 12:29, 18 January 2025 (UTC)
:A parachutist can onyl start as high as his ballon, so that would make no difference until paragliding became a sport (way too late). However, most highs are still utterly wrong due to the omission of high altitude balooning from the mid-19th century onwards: It seems that no true airplane has ever beaten older baloon records. AT ALL. In fact, among all the objects capable of aerodynamic flight, only the X-2, the X-15 and the Space Shuttle set new 'maximum manned altidude' records going beyond aerostats of their time. However, all three ascended in balistic, rocketpowered flight, only using the lift of their wings during return. So humanitys pinnacle has always been defined by people thrown of cliffs, people attached to kites, peoples in baloons or people on rockets. [[Special:Contributions/172.70.250.194|172.70.250.194]] 16:06, 18 January 2025 (UTC)

huh. no joke comic. [[user talk:lett‪herebedarklight|youtu.be/miLcaqq2Zpk]] 15:43, 18 January 2025 (UTC)

[https://en.wikipedia.org/wiki/Yuan_Huangtou Yuan Huangtou] is a strong contender for the question in the title text. As a punishment he was sent to the sky on a big kite which was then let go. He came down 2.5 km away and survived. It seems entirely possible that he may have reached altitudes of several hundred meters. [[Special:Contributions/162.158.95.196|162.158.95.196]] 19:05, 18 January 2025 (UTC)
:From my recollection of a book on Chinese kite history, I'd put the max for a person-carrying kite at around a couple hundred meters. [[Special:Contributions/162.158.41.9|162.158.41.9]] 04:59, 19 January 2025 (UTC)
:As a technical argument, I'd mention that what makes a kite a kite is that it is tethered (albeit dynamically, whether to a winch or a firmly ground-based handler, rather than necessarily ''tied to the ground''; this makes the kites in kite-surfing/sailing/skating/etc a bit of an edge condition, but still valid as the canchor' is only ever itself airborne by temporarily depleting the kite's 'lift ability').
:Unless it was at the end of a 2.5km tether, at least part of the time the kite was released became a glider. And the means for keeping a glider up (and then ultimately not descending too fast!) are somewhat different from how you make a kite controllable. Even if you successfully raised a man-kite up and brought them back down several times (getting both the payer-out person ''and'' the payload-person used to how to control the kite-flight), the attitude and augmenting flight-surfaces that the kite used to get/keep/maintain height would probably be entirely wrong (perhaps even counterproductive!) when the release happens and the 'passenger' needs to now suddenly develop the need to "fly a glider" (or, maybe, a suboptimal parasail)
:I would not be surprised if many (reluctant) 'test pilots' failed to work out how not to stall (and other forms of flight-failure) in the time and distance they had before they reached the ground. The later ones ''might'' have a better hash of it ''if'' they were taken to witness their first compatriots' efforts (and those initial 'candidates' were able to shout down what they were feeling/doing, during their final fateful moments, to assist both the builders and future-fliers)... But, in the days before ''any'' actual aviation experience (let alone any form of flight-recorder, for both easier detailing of events and the repeatable playback for their better analysis), quite a bit of luck (or some coincidentally instinctive panic-induced response to falling, perhaps somehow harking back to the most recent common ancestor with a sugarglider/flying-squirrel/etc) will have played a part in whoever it might have been who rode a once-kite-now-glider down.
:Or, possibly, part of the luck was that the released tether was long enough to ''drag'' on the ground (given the options for rope/chord, around that time, and possibly the spool it was unspooled from, before the spool itself was released (by accident/design)), and with a strong enough wind and a consistently 'draggy' free-tether, it maintained a kite-like flight profile for the suggested distance (never being any higher than when ground-tethered, but only ''very gradually'' losing its initial height), such that the CFIT at the end was a 'survivable' (legs first? kite-structure acted as an initial crumple-zone?) landing.
:Of course, it's at least partly a legendary account. Could be somewhat contrived from retellings and embelishments, 'originally' just being (out of many such 'experiments' with 'volunteers') a controlled rise that was then re-winched-in, conflated with what happened when the tether snapped/etc, during a particularly windy day, and where the resulting wreckage was discovered. I think it's ''possible'' it happened (and one might even be able to plan to re-enact it, with modern knowledge of aeronautics and hands-on experience with all the more recent methods and means of flying), but it sounds like it became known ''only'' because it was a memetic (and maybe composite) success, only having to compete with the few "glorious failures", not the many occasions where some basic idea (that ''may'' have eventually led to better ideas) just didn't work ''or'' notably fail. [[Special:Contributions/172.70.160.195|172.70.160.195]] 14:52, 19 January 2025 (UTC)

11 paragraphs should be 5-7. [[Special:Contributions/172.71.151.155|172.71.151.155]] 05:04, 19 January 2025 (UTC)

Annotated the image [https://imgur.com/a/nQ3FZdi here]... Green line is "current absolute record" (assuming the truth of the plot), blue line is "highest height that will now always have someone higher" (again, going by the plot), red line is "record by a living individual" (''based'' upon the plot, and several historical truths I could discern, but probably getting to be as much speculative as the original joke-plot-with-a-passing-basis-in-fact). [[Special:Contributions/172.69.79.164|172.69.79.164]] 01:39, 20 January 2025 (UTC)

In 1966 there should be a peak above 1000km, the [https://en.wikipedia.org/wiki/Gemini_11 Gemini 11 flight], September 12-15, 1966, which reached an apogee of 1,374 kilometers. [[User:Rps|Rps]] ([[User talk:Rps|talk]]) 17:01, 20 January 2025 (UTC)

It seems like the graph is ignoring USSR's [https://en.wikipedia.org/wiki/Mir Space Station Mir]. Per wiki, it was occupied for 12.5 years of its 15 year lifespan from 1986 to 2001. Honestly, feels like a weird thing to miss while including the ISS explicitly. [[Special:Contributions/172.70.207.140|172.70.207.140]] 06:45, 21 January 2025 (UTC)

Talk:3015: D&D Combinatorics

2024-11-23T02:53:53Z

172.70.207.140: maybe maybe not

The bot originally created this page as “D Combinatorics”. I renamed it to the correct title and tried to get as many of the references as possible (including a few redirects). [[User:JBYoshi|JBYoshi]] ([[User talk:JBYoshi|talk]]) 00:54, 23 November 2024 (UTC)

:The title in the Atom feed (which I'm assuming the bot consumes) is "D Combinatorics". I'm guessing something in Randall's pipeline didn't like the ampersand. --[[Special:Contributions/162.158.154.160|162.158.154.160]] 01:41, 23 November 2024 (UTC)

:By raw combinatorics: 71 + 52 + 34 + 20 + 10 + 4 + 1 ways to get each of 16 - 22 respectively, for a total of 192, out of 4(6^3) = 864 total. 192/864 simplifies to exactly 2/9. I have no idea how Randall found this; if anyone has an idea, please let me know. [[User:Kaisheng21|Kaisheng21]] ([[User talk:Kaisheng21|talk]]) 01:33, 23 November 2024 (UTC)

It seems like we edited the transcript at the same time. The odds of rolling 16 or higher in this situation seem to be 2/9? [[User:Darkmatterisntsquirrels|Darkmatterisntsquirrels]] ([[User talk:Darkmatterisntsquirrels|talk]]) 01:29, 23 November 2024 (UTC)

: There are 864 possible rolls (6 * 6 * 6 * 4). If you enumerate all of the rolls you will find that 192 are 16 or higher. 192/864 = 2/9, the value from the explanation. [[Special:Contributions/172.68.54.139|172.68.54.139]] 01:41, 23 November 2024 (UTC)

A much simpler approach: Roll two six sided dice and sum the result. You are successful if the result is 5 or 9. That happens 8 times out of 36. 8/36 = 2/9. (Or successful if the sum is 4 or 6, or 2 or 7, or 2,3,4 or 11, or several other combinations.) [[Special:Contributions/172.68.54.139|172.68.54.139]] 01:41, 23 November 2024 (UTC)
:Clever, but dice rolls in D&D involving summing all the dice, applying modifiers, if any, and then comparing to one or more threshold values. Your method makes it very difficult to apply modifiers. [[Special:Contributions/162.158.41.8|162.158.41.8]] 02:49, 23 November 2024 (UTC)

Minor quibble, arrows aren't fired (unless they're flaming or self-propelled, perhaps), they are shot. (Shotguns are fired of course.) [[Special:Contributions/162.158.41.73|162.158.41.73]] 02:52, 23 November 2024 (UTC)

3011: Europa Clipper

2024-11-14T11:53:53Z

172.70.207.140: /* Explanation */ explain

{{comic
| number = 3011
| date = November 13, 2024
| title = Europa Clipper
| image = europa_clipper_2x.png
| imagesize = 333x356px
| noexpand = true
| titletext = They had BETTER make this a sample return mission.
}}

==Explanation==
{{incomplete|Created by a JOVIAN DESSERT - Please change this comment when editing this page. Please DO delete this tag too soon.}}
[[File:Animation of Europa Clipper course around Jupiter.gif|thumb|right|The ''Europa Clipper's'' trajectory around {{w|Jupiter}}, represented as the stationary green dot. In gold is Jupiter's moon {{w|Callisto (moon)|Callisto}}, in cyan is the moon {{w|Europa (moon)|Europa}} — the primary target of the spacecraft's study — and in orange-red is the innermost of Jupiter's four largest "Galilean" moons, {{w|Io (moon)|Io}}. The spacecraft's track is shown in magenta. Jupiter's other Galilean moon {{w|Ganymede (moon)|Ganymede}} and its second largest moon {{w|Titan (moon)|Titan}} are not shown, but their gravity bears heavily on the ''Clipper's'' trajectory.]]

The ''{{w|Europa Clipper}}'' space probe was launched from the Kennedy Space Center in Florida, USA, on 14 October 2024. It is expected to arrive at Jupiter and begin exploration of Jupiter's moons, particularly {{w|Europa (moon)|Europa}}, in 2030.

Europa is an icy moon. Water ice covers its surface. Beneath the ice, there is expected to be liquid water, which may contain living microbes. To sample this liquid, its crust (water ice) would need to be broken.

In the comic, the surface ice is likened to the caramel crust on the dessert ''{{w|crème brûlée}}''. This dessert was invented in France{{acn}}, which is, of course, part of Europe. To eat the dessert, the crust is broken with a spoon. Having conflated Europa with Europe, the makers of the probe expect to encounter crème brûlée, and have equipped it with a spoon for the purpose of collecting samples. No such spoon is present on the actual spacecraft{{cn}}, whose trajectory is designed to ''avoid'' contacting Europa so as to prevent {{w|Planetary protection|contamination of any life there}} by microorganisms on the spacecraft.

The title text expands on the main joke by stating that the spacecraft "had BETTER" return samples of the dessert/water ocean to Earth, presumably because Randall is keen to taste the samples. (Although crème brûlée is often served with fruit, it is not mentioned whether Randall expects the sample to be served with {{w|Jupiter Icy Moons Explorer|Juice}}.) Desirable as this might be (for non-gustatory reasons, as the taste of Europa's water ocean would likely be a surprise to a person expecting a custardy flavor), it is impractical.

This may also be a reference to the Cassini-Huygens lander, which, shortly after landing on the surface of Saturn's moon Titan, detected a surface that was [https://www.sciencenews.org/article/world-unveiled-cr%C3%A8me-br%C3%BBl%C3%A9e-titan described] as having a creme brulee consistency.

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

:[A space probe with two rectangular solar panels, a circular dish of the front, and a massive spoon on the bottom, longer than the length of its solar panels]

:[Below the panel:]
:Good news: NASA's '''''Europa Clipper''''' is en route to Europa and has successfully deployed its crème brûlée spoon.

==Trivia==
The Clipper spacecraft was at one point to be developed alongside a lander, which was later dropped from being part of the same (or very closely partnered) mission. The latest version of the {{w|Europa Lander}} proposal is far behind the Clipper in implementation, not yet even being guaranteed funding.

Any actual sample return mission is currently far into the future of {{w|Ocean Worlds Exploration Program|the related plans for exploration}}, along with the possibility of digging deep enough into the ice to finally confirm or dismiss some of the more interesting theories about the world concerned.

In Arthur C Clarke's novel '''2010''', the monolith aliens tell humanity ''"All these worlds are yours - except Europa. Attempt no landing there."''

{{comic discussion}}
[[Category:Space]]
[[Category:Space probes]]
[[Category:Food]]