explain xkcd - User contributions [en]

2888: US Survey Foot

2024-02-01T22:21:23Z

172.71.150.154: while 610nm is technically a fraction of a millimeter (about 61/100000), referring to it that way is absurd

{{comic
| number = 2888
| date = January 31, 2024
| title = US Survey Foot
| image = us_survey_foot_2x.png
| imagesize = 740x606px
| noexpand = true
| titletext = Subway refuses to answer my questions about whether it's an International Footlong or a US Survey Footlong. A milligram of sandwich is at stake!
}}

==Explanation==
{{incomplete|Created by a 610 US-SURVEY-NANOMETER MONKEY - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

This comic pokes fun at a difference in length of the {{w|Foot_(unit)#U.S._survey_foot|US Survey Foot}} and the {{w|Foot_(unit)|International Foot}}. After Carl Edvard Johansson's {{w|Carl_Edvard_Johansson#Johansson_and_the_inch|gauge blocks}} in 1912 led to {{w|International_yard_and_pound|an international agreement}} in 1959, the foot has been defined to be exactly 0.3048 metres, whilst the US survey foot is defined as 1200/3937 meters as it continued to use the {{w|Mendenhall Order|definition of 1893}}, making it a bit longer than the international foot. However, the difference between the two is proportionately too small for most purposes, as they only differ by 2 parts per million. At foot-length scales, the difference is a fraction of a micron, with longer measures (where the error grows to a notable degree) requiring an already excessive implied precision likely to mismatch its true accuracy. Some engineering or scientific applications ''may'' involve such tolerances, but would be expected to consistently use some more modern standard of measurement to {{w|Mars Climate Orbiter|avoid such confusion}}.

In the fourth panel, Cueball says that [[Black Hat]] is drawing the world 610nm closer to madness, which is about the difference between the two measures (per foot). Cueball, outraged, then tells that the {{w|National Institute of Standards and Technology}} (usually abbreviated with NIST) has been authorized to capture Black Hat to stop him from using the US survey foot. The joke here is that his coordinates show that he is 8,000 miles away, but since he is using the US survey foot, he is 0.016 miles away from the search team, making them unable to find him at that exact spot. (A good strike team would likely keep looking, but perhaps being strictly NIST-trained to adhere to particularly exacting standards has ironically made them vulnerable to the same inaccuracies that they are supposed to be preventing.)

Note – 0.016 miles is about 28.16 yards (84.48 feet), or 84.4798 US Survey Feet, or 25.749 metres.

Randall is playing a bit fast-and-loose here. To make this joke work implies a rather absurd situation: that both Black Hat and the searchers have set their devices to measure and report location ''in reference to'' the same location (the place where Cueball is and that is one end of the 8,000 mile measurement) and not just use GPS and lat/long like every other smartphone on the planet. The only location that can be reasonably inferred based on the comic's info is NIST headquarters in Gaithersburg, Maryland. In the unlikely event that the searchers' phones measure and report location in reference to NIST HQ, evidently Black Hat has also overridden his device's in-built GPS to report its location in reference to NIST headquarters as a way to toy with them – a curious choice that the NIST strike team doesn't find suspicious – and then traveled EXACTLY 8,000 miles away, knowing NIST would be in hot pursuit. After all, Black Hat is known for his preternatural powers of mischief.

Where might Black Hat be hiding? If he was in U.S. territory that would give them clear jurisdiction over him, but there is no U.S. territory which is [https://www.mapdevelopers.com/draw-circle-tool.php?circles=%5B%5B12874687.81%2C39.1450494%2C-77.2161307%2C%22%23AAAAAA%22%2C%22%23000000%22%2C0%5D%5D exactly 8,000 miles from NIST headquarters in Gaithersburg, Maryland] (regardless of which foot is used). The closest U.S. territory would probably be Cocos Island, Guam, 7923.92 miles away from Gaithersburg; the closest U.S. jurisdiction is probably the U.S. Embassy in Dhaka, Bangladesh, at 8015.14 miles. This implies that Black Hat is not on U.S. soil, which means that the NIST strike team is operating in a legal gray area, like a SEAL team catching an international terrorist.

Part of the joke is the imaginative idea that NIST employs and dispatches strike teams to apprehend persons that use incorrect measurements.

The title text references a {{w|Subway (restaurant)#Sandwich_size|2013 lawsuit}} over the length of a "Footlong" sandwich sold by Subway fast food chain. However – in contrast to the issue at stake in that lawsuit – the difference in length between an 'international footlong' sandwich and a 'US survey footlong' sandwich is way below the precision ''or'' accuracy by which sandwiches are usually produced – making it understandable that Subway would not think it necessary to clarify which definition of 'foot' they use for their products.

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

:[Closeup on Cueball.]
:Cueball: We thought it was over. After 60 years of struggle, the US survey foot was dead, deprecated by NIST in 2023.

:[Cueball is shown to be talking to Ponytail, Hairy, and Megan. He has a presentation behind him.]
:Cueball: We thought architects and engineers could rest east, free of the headaches of having two conflicting definitions of the foot that differ by 610 nanometers.
:International foot: 0.304 800 000 m
:US survey foot [crossed over in gray] R.I.P.: 0.304 800 609... m

:[Cueball points at an image of Black Hat]
:Cueball: But I bring dire news:
:Cueball: ''Someone has started using the US survey foot again.''

:[Closeup on Cueball again.]
:Off-panel voice: Why!?
:Cueball: We don't know.
:Cueball: Some people just want to drag the world 610nm closer to madness.

:[Farther view of Cueball only. He clenches a fist.]
:Off-panel voice: What can we do!?
:Cueball: A NIST team is already in the air. We will capture the scofflaw and end this nightmare.

:[Two helicopters flying, with mountains in the background.]

:Caption: 8,000 miles away
:[Two operatives in a forest with "NIST" helmets. One talks on a walkie-talkie.]
:Operative: We've reached the coordinates of the target's device. There's no one here.
:Voice from walkie-talkie: How!?

:Caption: 8,000.016 miles away
:[Black Hat walking elsewhere in the forest, very close by.]
:Black Hat: ♫ ♪

==Trivia==

The number of miles in the last panel was [https://www.explainxkcd.com/wiki/images/archive/5/5f/20240131173446%21us_survey_foot_2x.png originally] 8,000.014, but was changed to 8,000.016. The latter matches the 2 ppm difference between the international foot and the US survey foot.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Black Hat]]
[[Category:Characters with hats]]
[[Category:Geography]]
[[Category:Food]]

Talk:2642: Meta-Alternating Current

2024-01-14T06:27:37Z

172.71.150.154: active vs reactive load

And today, we are reminded that [[Randall]] used to be a physicist (or at least has a physics degree). Not worth mentioning in the article, but while inverters can't reverse each other, transformers can. (Has Randall done the transformer/Transformer pun yet as an excuse to mock the movies?) [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 11:10, 7 July 2022 (UTC)
: I haven't picked up the physics reference yet. I see electrical engineering here. Randall strikes me as somebody who would study physics given the opportunit, though. It's notable that this webcomic started while Randall was in college, if I recall right. [[Special:Contributions/172.70.230.75|172.70.230.75]] 11:58, 7 July 2022 (UTC)

Long distance links, especially those between separate unsynchronized grids, use high voltage DC. There is a 2,000-mile link in China running at 1 MV. [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]]) 11:32, 7 July 2022 (UTC)
:That's because at great distances, relatively high frequency AC loses a lot of ("active" = actually useful) power as ... reactive power, I think (didn't learn the terminology in English, unit seems right though). A typical grid has a lot of generators and load. A long distance connection results in a phase shift according to the transmission time (speed of light in medium x distance) in about the order of magnitude of the AC period (usually somewhere between 1/10 to 1/60 seconds) wastes a portion equal to the sine of the phase shift angle (up to 90° = all of it) as reactive power. DC isn't quite as easy to use but on long distances there is no power loss to reactive power. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:25, 7 July 2022 (UTC)
::Do you have references? That doesn't seem right to me, speed-of-light lags ought to simply place widely separated power stations at different phase angles which appear the same, without causing a clash. And even in cases where there is an irreconcilable mismatch (say, if there's a loop flow), it's possible to use a "phase-angle regulating transformer" to match the phases. --[[Special:Contributions/172.71.150.154|172.71.150.154]] 06:27, 14 January 2024 (UTC)

Let's face it, the thing should be called an alternator. Of course that name's taken as a redundant word for (electrical) generator. [[User:627235|627235]] ([[User talk:627235|talk]]) 12:26, 7 July 2022 (UTC)
: Alternator and Generator shouldn't be used interchangeably. At least, in automotive, aerospace and industrial discussions, a generator is normally thought of as a DC device while an alternator is AC, even if we usually rectify it's output to 12 or 24VDC... [[User:SwervingLemon|SwervingLemon]] ([[User talk:SwervingLemon|talk]]) 19:33, 9 July 2022 (UTC)

It always bothered me that UPS battery backups take the wall AC and convert it to DC to charge the battery, but then have to turn it back to AC to send it to the computer, so the power supply can convert it to DC to run the thing. I picture some connector that goes directly from the UPS to the power supply so that if power is lost it can just pull 12V directly from the battery. [[User:Andyd273|Andyd273]] ([[User talk:Andyd273|talk]]) 12:47, 7 July 2022 (UTC)
:some UPSs do this. They normally power the computer directly from the input AC, but if there is a power failure, they use the battery to power the inverters and switch the output to the inverter. Other UPSs always power the computer from the inverter. They have the advantage that there is not even a milisecond time to start powering the computer. That can be better for some equipment, and that kind of UPS often costs more. It is also worth noting that in some data centers, they bypass the AC step and have one big DC power supply that directly powers the computers. [[User:WhiteDragon|WhiteDragon]] ([[User talk:WhiteDragon|talk]]) 16:49, 7 July 2022 (UTC)

[https://en.wikipedia.org/wiki/Inverter_(logic_gate) NOT logic gates] are also often known as inverters. An even number of those '''would''' indeed produce the same output as the (true/false) input. [[Special:Contributions/108.162.242.58|108.162.242.58]] 16:03, 7 July 2022 (UTC)

“Further chaining this into more inverters/rectifiers would normally not be considered.”
Well, if you take a DCC controlled model railway for camping, you get a second stage of inverter/rectifier.
The power supply of the DCC control station usually expects AC input, so you invert the DC of the car battery.
The PSU then makes DC for the control station processor, which is then made AC to generate a DCC signal.
The locomotives always have a rectifier to get a DC power supply from the DCC signal (which is confusingly AC).

You get a third stage with another plausible trick: put the battery on a car battery charger, which converts AC from the camping site power grid to DC. Then use a locomotive with a (rarely used) BLDC motor, which confusingly needs an inverter generating AC.
--[[Special:Contributions/172.71.94.181|172.71.94.181]] 18:01, 7 July 2022 (UTC)

The efficiency calculation is bogus. For the rectifier, the "efficiency" of 81% relates to voltage, not power. (See https://en.wikipedia.org/wiki/Rectifier). I don't know what the power efficiency is, but I do note that my computer's power supply is not glowing white hot.
:Where do you propose the extra current to make up for such difference would come from? [[Special:Contributions/172.70.206.213|172.70.206.213]] 21:38, 7 July 2022 (UTC)
::When you convert AC to DC or DC to AC, you can't qualify either with single number for voltage OR current. You need to examine whole graph, because both voltage and current are changing with frequency of (original) AC. I'm pretty sure that 81% figure is related to the different way how voltage is computed for AC and DC. That said, regarding the gloving power supply ... usually, power supply contains fan, and while it's partially used to cool the case interior, the power supply might not like it being stopped either. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 22:24, 7 July 2022 (UTC)
:Your computer's power supply has switching H-bridge MOSFET transistors that sense and match the AC phase, not an ordinary diode rectifier. [[Special:Contributions/172.70.206.213|172.70.206.213]] 23:25, 7 July 2022 (UTC)
:: The mains input bridge rectifier in every PSU I've seen is just a normal 4 diode bridge, it's at worst a 2% loss. The output from the transformer probably has synchronous rectification due to the much lower voltage, but not an H-bridge, instead a center-tapped transformer winding and 2 MOSFETs. The only H-bridge in a PSU is the inverter. [[Special:Contributions/141.101.76.233|141.101.76.233]] 21:43, 8 July 2022 (UTC)
::: Please see https://www.physics-and-radio-electronics.com/electronic-devices-and-circuits/rectifier/bridgerectifier.html "The maximum rectifier efficiency of a bridge rectifier is 81.2% which is same as the center tapped full wave rectifier." See also https://techweb.rohm.com/knowledge/acdc/acdc_pwm/acdc_pwm06/8786 [[Special:Contributions/162.158.166.183|162.158.166.183]] 19:36, 16 July 2022 (UTC)
:::: Sigh, that's for 5V DC output. A rectifier isn't some magic device that wastes a fixed percentage of power, it's just some bloody diodes. Your first "source" is rubbish, and your second source is for the output rectifier for a 5V DC power supply. [[Special:Contributions/172.71.94.187|172.71.94.187]] 22:56, 24 July 2022 (UTC)

I interpreted Randall imagining "inversion" as "reciprocal" (or maybe the inversion of a function) rather than physically turning something upside-down, since mathematical inversion is typically reversible... [[Special:Contributions/172.70.130.121|172.70.130.121]] 03:48, 8 July 2022 (UTC)

Should the description also comment on the choice of number for this "connector". Obviously related to the fact that wall outlet voltage in the US is frequently (pun intended) 120 Volts. [[User:MAP|MAP]] ([[User talk:MAP|talk]]) 14:41, 8 July 2022 (UTC)

Two inverters *can* cancel each other out if they are the simplest type (a commutator, a.k.a. square wave inverter) *and* they happen to be synchronous. Expect glitches at the commutation points though! [[Special:Contributions/172.70.210.125|172.70.210.125]] 16:39, 8 July 2022 (UTC)
: Totally irrelevant to the comic. [[Special:Contributions/172.70.211.52|172.70.211.52]] 20:58, 8 July 2022 (UTC)
:: How is it irrelevant?
::: The comic is about "meta alternating" pairs of consumer inverters and rectifiers, not idealized chains of the same circuit. [[Special:Contributions/172.70.206.213|172.70.206.213]] 00:58, 9 July 2022 (UTC)
:::: The title text is about pairing two inverters and having them cancel each other out. It's relevant. [[User:SwervingLemon|SwervingLemon]] ([[User talk:SwervingLemon|talk]]) 19:33, 9 July 2022 (UTC)

And another one marked "Done" (by removing the Incomplete bit) and then the same editor making further changes (and then correct their change). Wrong way round, mate! Make sure it's correct, make changes you really feel need making and then subsequentally (ideally after checking your addition) make your bold proclaimation of it being Complete. [[Special:Contributions/172.70.85.13|172.70.85.13]] 22:01, 24 August 2022 (UTC)

2880: Sheet Bend

2024-01-13T18:39:33Z

172.71.150.154: /* Explanation */

{{comic
| number = 2880
| date = January 12, 2024
| title = Sheet Bend
| image = sheet_bend_2x.png
| imagesize = 317x244px
| noexpand = true
| titletext = A left-handed sheet bend creates a much weaker connection, especially under moderate loads.
}}

==Explanation==
{{incomplete|Created by a SHEETTY BEND - Please change this comment when editing this page. Can anyone elaborate on of this knot is right handed and what the differnces to a left handed would be and why this would decrease the strength of the knot as mentioned in the title text. Do NOT delete this tag too soon.}}
This is the seventh installment in the series of [[:Category:Cursed Connectors|Cursed Connectors]] and presents Cursed Connectors #46: The Sheet Bend. At the time of release this was the lowest number used for a cursed connector, with #286: [[2507: USV-C]] being the one with the highest number after those seven comics.

This comic shows two double-core wires being joined to make an electrical connection. Instead of the join being made the conventional way, that is, silver being joined to silver and gold being joined to gold within the insulating white cable, the diagram shows each core being connected to a ductile outer sheath, then the wires being tied together such that the outer sheaths touch and the connection is completed that way.

Although a fanciful extreme, this is a scenario commonly encountered by hobby engineers from the last millenium, who may have experience in electrical soldering and strong knowledge of how devices interconnect, but not always actual experience with professional repair, when handling the common situation of a broken wire. A hand-repaired wire can easily break again, and so hobby repairists can come up with solutions such as the tying the wire together. The proposed fanciful solution shows experience with both electrical work and knot work, and can appear quite satisfying with regard to how the knot holds the tension of the cable in a way that actually would strengthen the electrical connection rather than breaking it.

This is not the way electrical connections are usually made, as those familiar with larger currents are aware you might get an electric shock or start a fire from touching the outer side of the wires unless additional insulation is placed around the knot. Most connectors, even those like the relatively exposed {{w|punch-down block}} or {{w|screw terminal block}} types, would use some structural housing (and even {{w|AC power plugs and sockets#Protection from accidental contact|other methods}}) to ensure that the 'live' ends of a socket/plug/hybrid terminator are not trivially contactable to other exposed wires or objects/people, generally according to the relative dangers from, or to, the equipment to which the cable is connected.

The knot is designed to prevent the two connectors from touching, but this guarantee is not as strong as it could be, which would short out the circuit, but there is also the possibility of the cable slipping loose (perhaps by improper tensioning or handling of the knot, from the start) and the exposed conducting sheaths making other improper/dangerous connections across or beyond the knot itself. In both cases, the connection of the 'connector' would be at least become unreliable, even if it only disconnected the intended contact-points due to slippage – whether or not it became mechanically untied.

People who use “repair” jobs like this usually retain awareness and experience to continue learning and repairing as further issues develop.

The knot used to tie the two halves of the cable is a {{w|sheet bend}}, which is often used to join two ropes of different thicknesses, and explains the name for this type of cursed connector.

The title text says that a left handed sheet bend would provide a weaker connection. An actual left handed sheet bend provides less strength to the knot. This makes the title text a pun on the double meaning of "moderate load" (as in a moderate amount of physical tension applied through the cables ''or'' a moderate amount of electrical current passing through them). The difference between a left handed and right handed sheet knot is the free ends of the knots are on the same side in a right handed sheet knot (here both on the bottom side), but on opposite sides in a left handed sheet knot. When there is more tension pressing two conductive surfaces together, there is less resistance between them, strengthening the electrical connection as well.

==Transcript==
:[Above the drawing there is a header. Below the header there is a double-core wire going in from the left and stopping just past the middle of the picture. It shows how the inside of the wire looks and how the silver and golden wires inside are connected to two rectangular pieces of silver and golden material respectively. The golden piece is to the left and the silver piece to the right, closest to the end of the wire. Beneath this wire is shown two double-core wires forming a knot of the sheet bend type. Here it becomes clear that the silver and golden pieces are on the outside of the wires (but connected to the wires running inside the wires). In the knotted part of the wires gold touches gold and silver touches silver, without them touching the other color. Beneath this knot there is a label for the connector.]
:Cursed Connectors #46:
:The Sheet Bend

{{comic discussion}}

[[Category:Cursed Connectors]]
[[Category:Comics with color]]

2877: Fever

2024-01-05T20:33:30Z

172.71.150.154: Started a table representing the comic

{{comic
| number = 2877
| date = January 5, 2024
| title = Fever
| image = fever_2x.png
| imagesize = 514x587px
| noexpand = true
| titletext = Hypothermia of below 98.6 K should be treated by leaving the giant molecular cloud and moving to the vicinity of a star.
}}

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

{| class="wikitable" style="margin:auto"
|+ Table describing
|-
! Fever Temperature (Celsius) !! Equivalent Fahrenheit temperature !! Treatment !! Additional notes
|-
| 38-40 || 100-104 || Fluids, rest, normal doctor stuff || Normal fever temperatures.
|-
| 40-45 || 104- || Hospital, advanced doctor stuff || Point at which humans might start experiencing brain damage from fever.
|-
| 45-100 || || Example ||
|-
| 100-400 || || Example ||
|-
| 400-500 || || Example ||
|-
| 500-1,500 || || Example ||
|-
| 1,500-5,000 || || Example ||
|-
| 5,000-6,000 || || Example ||
|-
| 6,000-50,000 || || Example ||
|-
| 50,000-20,000,000 || || Example ||
|-
| 20,000,000-10,000,000,000 || || Example ||
|-
| 10,000,000,000 or higher || || Example ||
|}

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

:Treating a Fever

:Fever   Treatment
:38°C-40°C (100°F-104°F): Fluids, rest, normal doctor stuff
:40°C-45°C: Hospital, advanced doctor stuff
:45°C-100°C: Exit that steam cloud immediately
:100°C-400°C: Stop, drop, and roll
:400°C-500°C: Return to Earth from Venus ASAP
:500°C-1,500°C: Please climb out of that volcano
:1,500°C-5,000°C: Turn your tunneling machine around and come back up to the surface
:5,000°C-6,000°C: No, the surface of the '''Earth''', not the Sun
:6,000°C-50,000°C: Wait, that's not the Sun. What star are you visiting? Come back right now.
:50,000°C-20,000,000°C: At least stay on the '''surface''' of the star instead of diving down to the core
:20,000,000°C-10,000,000,000°C: You know, you could've picked a normal star instead of one that's exploding
:10,000,000,000°C or higher: I hope you're enjoying your visit to the Big Bang but you should really come back home immediately

{{comic discussion}}

Talk:2867: DateTime

2023-12-15T19:51:20Z

172.71.150.154:

Comics like this are why this wiki exists. [[Special:Contributions/172.70.100.172|172.70.100.172]] 23:30, 13 December 2023 (UTC)
:The time falsehoods gist linked above is a really good explanation about why a programmer might panic about calculating time. Especially the ones about calling "getCurrentTime()" twice in a row doesn't always mean the results are in the order you think they were called, or even different values. t2 might very well be the same or less than t1. It can be maddening. [[Special:Contributions/162.158.197.149|162.158.197.149]] 23:40, 13 December 2023 (UTC)
::The last item is the most important to me: ''Users prefer to use the local timezone.'' This causes so much frustration while browsing the web! [[File:PissedOff.gif]] --[[Special:Contributions/162.158.110.68|162.158.110.68]] 00:26, 14 December 2023 (UTC)
::Worth noting that events can take place over long periods. A sunspot or an illness or a relationship doesn't happen at a single point in time, it takes place over days or weeks or longer. When did it "start"? Who knows? Also I miss calling TI4-1212 here in DC. [[Special:Contributions/172.70.175.27|172.70.175.27]] 01:39, 14 December 2023 (UTC)
::Out of curiosity, could someone explain the item in that time falsehoods list that says "Months have either 28, 29, 30, or 31 days"? My guess is that it's a reference to their being more calendars in the world than Gregorian? But I'm not sure if there's more than that going on, there.[[User:ModelD|ModelD]] ([[User talk:ModelD|talk]]) 18:18, 14 December 2023 (UTC)
:::Isn't that true of Gregorian calendars? February has 28 or 29 depending on the year, AJSN have 30 and JMMJAOD have 31.[[User:Gavin|Gavin]] ([[User talk:Gavin|talk]]) 18:33, 14 December 2023 (UTC)
::::It's saying that "months have either 28, 29, 30, or 31 days" is a falsehood. The first one that comes to mind is the [https://www.timeanddate.com/calendar/julian-gregorian-switch.html switch from the Julian calendar to the Gregorian calendar]: "In North America, for example, the month of September 1752 had only 19 days, as the day count went straight from September 2 to September 14". [[Special:Contributions/172.70.43.108|172.70.43.108]] 21:03, 14 December 2023 (UTC)
:::: (Ninjaed, with an actual example! But retrying reply anyway as it had other details.) But how many days had <insert your choice of month(s) during which a given system changed from Julian to Gregorian>? I think possibly, without looking up when each and every transition occured, below 20 days is possible. (As in the ''n''th of one month to the ''n''th of the next is less than 20 days, for the right month and a number of ''n''s. For other ''n''s, you can only actually count from the month before to the month ''after'' (two full calendar months), the daycount for that being below the typical bimonthly stretch of 59, 60, 61 or 62 days (under more standard conditions)... [[Special:Contributions/172.70.90.48|172.70.90.48]] 21:07, 14 December 2023 (UTC)

Related insanity on Computerphile with Tom Scott: https://m.youtube.com/watch?v=-5wpm-gesOY [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 03:54, 14 December 2023 (UTC)

Even with just Special Relativity, the question doesn't really make sense, because the answer will depend on the inertial reference frame. "Impossible to know and a sin to ask" is not a bad way to describe questions about non-invariants. [[Special:Contributions/162.158.154.189|162.158.154.189]] 08:09, 14 December 2023 (UTC)
:Is it even ''possible'' for two observers to agree on the answer and be sure that it's correct for both of them? [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 16:53, 14 December 2023 (UTC)

I can see Randall's point, so for your average everyday programming I'd say "please use a library function instead of trying to do it yourself, or you'll end up like the guy in the lower frame..." --[[User:IByte|IByte]] ([[User talk:IByte|talk]]) 11:02, 14 December 2023 (UTC)

When I googled "DateTime" all I came up with was Python libraries, nothing about relativity or other effects. Is that what Randall's talking about? [[Special:Contributions/172.69.22.125|172.69.22.125]] 22:03, 14 December 2023 (UTC)
:Ideally, the standard library functions for a language would cover many of the "quirks" without the programmer having to worry about remembering the details. The required inputs for the functions would be sufficient to determine the necessary offsets. But programmers still have to be careful about some of the issues, and not all languages (and their libraries) are sufficient for all situations. When things like relativistic effects have to be taken into account, the usual languages (and their libraries) don't have the needed flexibility/complexity and precision. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 00:18, 15 December 2023 (UTC)
::I should clarify, I'm not saying the Python library doesn't have functions for those quirks. I'm just asking: what does Randall mean when he says "DateTime" (two capital letters, no space, as per the comic title)? Is he talking about the Python library? Or something else I didn't find yet?[[Special:Contributions/172.69.134.163|172.69.134.163]] 02:51, 15 December 2023 (UTC)
:::Doesn't matter. For one the usage of CamelCase in such cases is pretty much standard regardless of language and besides of that the problems he's talking about/implying are pretty much true for every language. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 10:58, 15 December 2023 (UTC)

:::The majority of libraries that provide time-calculation services call it something along the lines of DateTime. The reason you're getting Python results is because Python is currently the most popular programming language, especially for people learning to program. --[[Special:Contributions/172.71.150.154|172.71.150.154]] 19:51, 15 December 2023 (UTC)

The recently-added link for "hyperbolic" goes to a W'pedia page for "Hyperbolic motion (relativity)". This is obviously intended as a joke, but I'm not convinced that an unmarked joke like this is appropriate. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 16:04, 15 December 2023 (UTC)