explain xkcd - User contributions [en]

1337: Hack

2025-05-21T04:09:35Z

172.70.208.76: /* Updates for ISEE-3/ICE */

<noinclude>{{distinguish|:Category:1337{{!}}the 1337 series}}</noinclude>
{{comic
| number = 1337
| date = March 3, 2014
| title = Hack
| image = hack.png
| titletext = HACK THE STARS
}}

==Explanation==
This comic is an imagined project to re-position the {{w|International Cometary Explorer|ISEE-3/ICE}} probe, and a parody of the 1995 movie ''{{w|Hackers (film)|Hackers}}''.

The history of the probe, as laid out in the comic, is true. The probe did, indeed, return to signal range in 2014, and seemed capable of being controlled, but NASA declined to devote the resources necessary to re-establish communication. The proposed, independent project to take control of the probe and send it on a new mission didn't exist at the time of the comic, but has since [http://spacecollege.org/isee3/ become reality], as [[Randall Munroe|Randall]] noted in a [https://blog.xkcd.com/2014/05/30/isee-3/ blag post]. See [[#Background for ISEE-3/ICE|details below]].

The film ''Hackers'' was about the exploits of a group of teenage computer hackers, and their adventures in gaining unauthorized access to various systems. Like many fictional depictions of hacking, the film was heavily criticized for its lack of technical accuracy, but it did a lot to interest mainstream youth at the time in hacker culture. The primary protagonist goes by the handle "Crash Override", and his rival (and love interest) goes by "Acid Burn". The film ends with the two of them in a swimming pool, on their first date, with the lights in several nearby buildings spelling out "Crash And Burn", in Crash's latest hack/romantic gesture.

The strip depicts a scene in the satellite's control room, which plays out like many of the hacking scenes in the movie, with the system operators being shocked and flummoxed at being locked out of their own system, while an unauthorized party takes control and sends alternative instructions. The screen displays the phrase "mess with the best, die like the rest", which was Crash's signature phrase in the film.

The final row depicts a recreation of (or sequel to) the final scene of the film, with Crash and Burn once again swimming together. This time, however, Burn tells Crash to "make a wish", immediately before a shooting star appears in the sky (there's a tradition of making wishes when shooting stars appear in the sky). The implication is that Burn is the one who hacked the satellite controls and that she placed the satellite on a course for earth, causing it to burn up in the atmosphere in exactly the right time and place to create her own shooting star. This is arguably a much more impressive feat than controlling building lights, and definitely one-ups his previous romantic gesture. Since the ability to do something so dramatic by hacking computer systems depended on a very specific and rare set of circumstances, it's unlikely that he'll ever be able to top it.

The comic number is 1337, which stands for "leet", short for "elite hacker" and "leetspeek" in {{w|leetspeak}}. Leetspeak is a form of symbolic writing that substitutes various numbers and {{w|ASCII}} symbols for letters. It originates from the hacker subculture, where words were converted to leetspeek e.g., to avoid filters and triggers on chat rooms. "1337" for "leet" can most likely be explained as {{w|calculator spelling}}.

The title text "Hack the stars" is also an allusion to ''Hackers'', where the phrase "Hack the planet!" is used on multiple occasions. The movie was previously referenced in [[689: FIRST Design]] and [[1247: The Mother of All Suspicious Files]].

==Transcript==
:[A black image shows an image of the ISEE-3/ICE spacecraft in white. Text is written in white above it]
:The ISEE-3/ICE probe was launched in 1978.
:Its mission ended in 1997 and it was sent a shutdown signal.

:[The text continues, black on white, without a frame around it, between the first frame and the next.]
:In 2008, we learned-to our surprise-that the probe didn't shut down.
:It's still running and it has plenty of fuel.
:...and in 2014, its orbit brings it near earth.

:[Megan holding up one hand and Ponytail are talking to each other.]
:Megan: We could send it on a new mission...
:Megan: Except we no longer have the equipment to send commands to it.
:Ponytail: Can't we—

:[Zoom in on Megan's head and torso as she looks towards Ponytail off-panel to the right.]
:Megan: NASA won't rebuild it. "Too Expensive"
:Ponytail (off-panel): ''Seriously?''
:Megan: I know, right?
:Megan: So the internet found the specs
:Megan: And we went to work.

:[Megan and Ponytail are walking towards right, between Hairbun facing left and Cueball (with head phones) facing right. They are sitting at desks working on their laptops. Megan speaks, as indicated both by the story line and by her hand which is lifted up, but there is not speech line from her to the text.]
:Megan: We've convinced them to give us time on the Madrid DSN transmitter and hacked the maser to support the uplink.
:Megan: And today's the big day.

:[Zoom in on Cueball's head and torso, he holds a hand up to his speaker on his head phones and watches his lit screen (as indicated by lines emanating from it).]
:Cueball: Transmitting...
:Cueball: We have a signal!
:Cueball: We have control!

:[Zoom in on Megan's head and torso. She has turned away from Cueball to the right towards Hairbun.]
:Megan: OK, transmit the new comet rendezvous maneuver sequen—
:Cueball (off panel): What ''the hell?''
:Megan: What?

:[Same setting as when Megan and Ponytail entered the control-room, but Ponytail just stands there and Megan puts a hand out towards Cueball.]
:Cueball: My console went dead!
:Hairbun: ''Mine too!''
:Megan: What's happening?!

:[Another zoom in on Cueball's head and torso and glowing screen. He has both hands down.]
:Cueball: There's a new signal going out over the transmitter!
:Megan (off panel): A bug?
:Cueball: ''Someone else is in the system!''

:[Zoom in on Hairbun's head and torso. She is also working on her laptop, with the glowing screen visible.]
:Hairbun: Kill the connection!
:Cueball (off panel): ''I can't find it!''
:Hairbun: ''They're firing the probe's engines!''
:Cueball (off panel): ''No!!''

:[Back to a zoom in on Cueball. He points at his screen.]
:Megan (off panel): ''Who's '''doing''' this??'' Stop them!
:Hairbun (off panel): ''I'm trying!''
:Cueball: ''Look! My screen!''

:[Same setting as when Megan and Ponytail entered the control-room, but Ponytail has a hand to her mouth and she and Megan stand close to Cueball who has taken his hands off the keyboard. The text on Cueball's laptop screen is shown above the setting, indicated with zigzag lines:]
:M-E-S-S-W-I-T-H-
:T-H-E-B-E-S-T

:D-I-E-L-I-K-E-
:T-H-E-R-E-S-T

:[The last four panels is outside night scenes with a black sky above. In the first of these a woman (Burn) with long hair (Megan like) and a hairy man (Crash) is seen in a swimming pool with blue water.]

:[A zoom out reveals that the pool is on top of a skyscraper in a vertically developed, downtown setting with lots of light in all the skyscrapers, one of which is even taller than the one with the pool. From the top of the central skyscraper speech lines come which indicate that the two from the pool is up there speaking, and we get their names from this panel.]
:Burn: Crash?
:Crash: Yeah, Burn?

:[Same setting but only one speech line.]
:Burn: Make a wish.

:[The last panel shows the same setting, but with the spacecraft streaking across the sky as it enters the Earths atmosphere and burns up in a way that is indistinguishable from a meteoroid.]

==Trivia==

===Background for ISEE-3/ICE===
The {{w|International Cometary Explorer|ISEE-3/ICE}} probe was launched in August 12, 1978 and tasked to study Earth's magnetic field and the solar wind. Before completing its original mission the probe was repurposed on June 10, 1982 to study the interaction between the solar wind and a cometary atmosphere. By flying through the comet {{w|21P/Giacobini–Zinner|Giacobini-Zinner}}'s tail, it became the first probe to do so. This put ISEE-3 in a {{w|heliocentric orbit}}. Its trajectory will bring it close to Earth on August 2014.

The Deep Space Network (DSN) detected the probe again in 2008 because NASA mistakenly left its transmitters on. However, the probe was only transmitting the carrier signal at that time. A status check of the spacecraft has revealed that [https://www.planetary.org/articles/02070836-isee-3 many of its instruments are still working and that it contains plenty of fuel.]

It was reported that the hardware to communicate with ISEE-3/ICE had been decommissioned. The Madrid DSS complex still has the special filter required to communicate with the ICE satellite, but because of frequency conflicts [https://deepspace.jpl.nasa.gov/dsndocs/810-005/101/101E.pdf S-band uplink is not supported.]

On March 1 and 2, 2014 radio amateurs were able to detect the beacon signal from the retired NASA deep space probe ICE (International Cometary Explorer) using the 20 m [https://amsat-uk.org/2014/03/09/radio-amateurs-receive-nasa-isee-3ice-spacecraft/ radio telescope at the Bochum Observatory (Germany).]

===Updates for ISEE-3/ICE===
After this comic was published, it was established that an 18-meter satellite dish at the Johns Hopkins Applied Physics Laboratory does still have the right hardware.
*April 4, 2014: Volunteers started a crowdfunding project on RocketHub to contact the probe and [https://web.archive.org/web/20140417052853/https://www.rockethub.com/42228 put it back into a halo orbit around Lagrangian point L1.]
*May 23, 2014: First contact to the probe was established.
*May 29, 2014: NASA gave them approval to try to achieve contact.
*May 30, 2014: The project, led by [http://www.rockethub.com/profiles/68340-dennis-wingo Dennis Wingo] and {{w|Keith Cowing}}, had taken control of the spacecraft.
*July 2, 2014: The reboot project successfully fired the thrusters for the first time since 1987. The engines on ISEE-3 performed a successful spin-up burn. The spin rate was changed to 19.76 rpm which is inside of the original mission specifications at 19.75 +/- 0.2 rpm.
**Further attempts to change the trajectory into an earth bound orbit did fail. Despite the effort from experts and [https://spacecollege.org/isee3/we-are-borg-crowdsourced-isee-3-engineering-and-the-collective-mind-of-the-internet.html amateurs via the internet]. was determined that the spacecraft had run out of nitrogen pressurant.
*Since the device was still communicating, and many of the instruments were still working, the ISEE-3 was intended to be used for [https://spacecollege.org/isee3/announcing-the-isee-3-interplanetary-citizen-science-mission.html the first citizen science, crowd funded, crowd sourced, interplanetary space science mission.].
*{{w|International_Cometary_Explorer#Contact_lost|Contact was finally lost}} on 2014-09-16.

See [http://spacecollege.org/isee3/ Space College: ISEE-3 Reboot Project Archives] for the coverage of this amazing project.

== References ==
{{reflist}}

{{comic discussion}}

[[Category:Comics with inverted brightness]]
[[Category:Comics with color]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairbun]]
[[Category:Space probes]]
[[Category:Astronomy]]
[[Category:Computers]]

3086: Globe Safety

2025-05-08T04:38:58Z

172.70.208.76:

{{comic
| number = 3086
| date = May 7, 2025
| title = Globe Safety
| image = globe_safety_2x.png
| imagesize = 255x448px
| noexpand = true
| titletext = Frankly, given their extreme gravitational fields and general instability, even 12-inch globes should probably be banned.
}}

==Explanation==
{{incomplete|This page was created recently. Don't remove this notice too soon.}}
A Schwarzschild radius of a given object is the radius of the event horizon of a black hole with the mass of that object. Since the Schwarzschild radius of the earth is about 0.7 inches, this hypothetical Globe Safety avoids creating black holes.
The title-text takes this situation further, by suggesting the 12-inch globes should also be banned, due to their extreme density and gravitational field.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>

Talk:3038: Uncanceled Units

2025-01-17T21:12:31Z

172.70.208.76:

DUDE I'M STILL IN SCHOOL RN, WHAT?
(also, the joke is that energy is power*time, so kWh is kJ/s... in an hour [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 13:27, 15 January 2025 (UTC)

I guess not every comic can be a winner. Talking about an appliance using a certain amount of kWH per day is clear and normal. Power gets billed by the kWh, not the Joule. While technically not wrong, wanting "cancel" a sub-part of the commonly-used energy unit kWh and leaving it in deliberately-obscured units most people are less familiar with is the sort of insanity I'd more expect from White Hat than Cueball. [[Special:Contributions/172.70.35.171|172.70.35.171]] 13:39, 15 January 2025 (UTC)
:Maybe that is a meta-joke? To frame kWh/day as something crazy by giving that line to whitehat --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 13:52, 15 January 2025 (UTC)
:There's a difference between instantaneous power draw, and the total "volume"(/area, really) of power over time. Though a fridge is "always on", it is still only irregularly at full-draw. But, to the power company (or to the gas company, who will generally give a kWh measure of 'energy taken from the network'), they don't (generally) care whether you used twice as many kW over half the time or half as many over twice the time, within any given total billing period, even if it affects what you think. [[Special:Contributions/172.70.163.46|172.70.163.46]] 14:39, 15 January 2025 (UTC)
::Using joule as if it was an everyday unit of energy would be weird but I don't agree that watt is crazy. It's a normal unit of energy consumption that does mean something to people, e.g. 1000W microwave, 100W (incandescent) light bulb. Don't get me wrong kWh/day is also useful to translate it to your energy bill, but I do feel slightly uncomfortable every time I see that time divided by time :-) [[User:Mtcv|Mtcv]] ([[User talk:Mtcv|talk]]) 14:40, 15 January 2025 (UTC)
:I don't think the complaint is that it's unclear, it's that Cueball/Randall instinctively wants units simplified - as they would be in a science context rather than a useful-for-normal-people's-everyday-needs context. [[Special:Contributions/108.162.238.183|108.162.238.183]] 02:40, 16 January 2025 (UTC)
:Yes, it is normal, but to people who know what it means it hurts to look at. kWh are a measure of energy that is technically SI-friendly and at a useful scale, but from an scientific perspective there isn't a great reason (to my knowledge) other than convention to not just use megajoules (1 kWh is 3.6 MJ). That on its own bothers me, and probably Randal based on a lot of his other comics. The added complaint here is that by making them per/day it is back to a measure of power (which kW measure) [[User:Stardragon|Stardragon]] ([[User talk:Stardragon|talk]]) 23:34, 16 January 2025 (UTC)

This is especially funny with US units. My car needs about 5l/100km, or 0.05mm². Now I am wondering how many ft^(-2) my car does... --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 13:49, 15 January 2025 (UTC)
: You make a good point about the units (at least in one instance). Shouldn't the reduced units for fuel economy be inverse area? Effectively, it is a measure of the distance the vehicle could travel while consuming a column of fuel with a specific height and specific top (or bottom) surface area. Or, The better the fuel economy, the less the surface area that is necessary to move a specific distance. [[User:SammyChips|SammyChips]] ([[User talk:SammyChips|talk]]) 20:41, 15 January 2025 (UTC)
::It depends on what the original unit is. In my country (Germany) we measure it in volume/distance, which would reduce to area. North American convention is in distance/volume which would reduce to inverse area. Good thing about distance/volume is that "high number = good". However I think outside of escaping from a nuclear disaster or in a zombie apocalypse it isn't a really helpful thing to know. Because how often do you know "I got x amount of fuel. Wonder how far I can get." But you will likely be in the situation where you quickly want to see "How much fuel do I need to get to place x which is y distance from here". --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 21:57, 15 January 2025 (UTC)
::: how often do you know "I got x amount of fuel. Wonder how far I can get." Quite often, because the question I'm really asking is whether I can get where I'm going with some margin built in before I need to refuel my car. When I do refuel or recharge the car, I'll go to 100% of capacity. I just want to know whether I have to do that now or if I can wait and do it later because later would be more convenient. The only time I want the number the other way is when I'm buying a car and want to make it as efficient as possible. Once I have it, the amount of fuel I need isn't going to change.[[User:Yttrium|Yttrium]] ([[User talk:Yttrium|talk]]) 09:02, 16 January 2025 (UTC)
::::Mhh... probably a question of what one is used to. If I need to go 400 km, and I know my car uses 5l/100km, I just multiply 4*5 to see that I need 20l, and will know if what I have is enough or not. But I guess with mpg you can do a just as easy calc: If my car gets 50mpg (roughly 5l/100km) and I have 5 gallons (roughly 20l), I can go 50*5=250 miles, which is roughly 400km. My nitpick is: My car, and I think all cars I ever drove just shows me a dial from empty to full. Knowing how much "full" is, I can estimate how much gas I have, while my GPS will tell me a pretty exact number of km I need to go. So if I am fuelling up on a monday morning (where gas tends to be more expensive in my area than on other times), or fuel up right before I get my next salary, I might just put in as much as I need right now. But yes, maybe/probably it is mostly a thing about habits and what you are used to. And might be more of an European issue, since fuel is basically free in North America in comparison. So I guess everyone just fuels up fully all the time, but has to be cautious to reach the next gas station when travelling through the more sparely-populated areas...--[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 10:19, 16 January 2025 (UTC)
:: More usefully imagined as the front (or back) end of a horizontal column (or, twisting as it may, a pipeline) that traverses the journey made by the vehicle. As if (instantaneous variations excepted) you consume precisely the fuel that your vehicle passes 'through/around'. [[Special:Contributions/141.101.76.92|141.101.76.92]] 20:45, 15 January 2025 (UTC)
::: Yeah. Maybe we should express fuel consumption in terms of the speed fuel needs to be drawn through a standard fuel line. [[User:SammyChips|SammyChips]] ([[User talk:SammyChips|talk]]) 21:01, 15 January 2025 (UTC)

fridge [[Special:Contributions/172.70.126.147|172.70.126.147]] 14:22, 15 January 2025 (UTC)

The late [https://en.wikipedia.org/wiki/David_J._C._MacKay Sir David MacKay] wrote an excellent book, [http://www.withouthotair.com/ Sustainable Energy – without the hot air] (which is available free online).
On [http://www.withouthotair.com/c2/page_24.shtml this page] he talks about the units he uses in the book: kWh for energy ("one unit") and kWh/day for power - becuase it's simple for lay-people to understand - how many units does this appliance use per day.
It's a good book if any of you are interested in sustainable energy (although it was written in 2008, so some bits might be out of date by now) {{unsigned ip|172.70.85.33|14:33, 15 January 2025}}

If anyone's curious, I found an online gallons per square foot calculator: https://www.omnicalculator.com/construction/gallons-per-square-foot [[Special:Contributions/172.71.223.6|172.71.223.6]] 15:54, 15 January 2025 (UTC)

The answer to Cueball's question is likely NO in the US and YES in the UK, due not just to gallon size but also fridge size (a model like that is a particularly large fridge, when I bought one 10 years ago going for the smallest available I had to modify my cabinet above the fridge as there wasn't one less than 6'8"- the fridge hole was 6' previous).[[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 16:02, 15 January 2025 (UTC)

I disagree with this comic, and I think the final paragraph in the explanation about Hubble's constant best explains why. [[User:Beanie|Beanie]] [[User talk:Beanie|talk]] 15:57, 15 January 2025 (UTC)
:It doesn't make any sense to 'disagree' with an observation.[[Special:Contributions/141.101.98.245|141.101.98.245]] 09:36, 16 January 2025 (UTC)

Hubble's constant can be expressed in reciprocal seconds, but it should not be expressed in Hz. Hz are reserved for repeating phenomenon. There is insufficient evidence of a cyclic universe. Using Hz could be an attempt to insert an unwarranted assumption into cosmology. This type of subtle "propaganda through choice of units" happens fairly often. Changing units can give a different perspective. Usually this will be through simplification because there is no algorithmic method to choose useful complex units.[[Special:Contributions/172.71.167.69|172.71.167.69]] 18:32, 17 January 2025 (UTC)

Technically, kWh should be written as kW⋅h or kW h, because it literally means "kilowatts multiplied by one hour", not "kilowatts per hour" as many people assume. However, almost nobody writes it correctly. (kW/h is sometimes also seen, but egregiously incorrect.) Also, particularly now that electric vehicles are becoming more popular, people often get confused between kW and kW h. The car can charge at a peak or average rate expressed in kW, but energy billed by a charging service provider is expressed in kWh. People frequently either add or remove the "h" incorrectly because they don't understand the difference. In some places like India, a kilowatt-hour is simply referred to as a "unit" to avoid confusion. In my opinion, it was an enormous mistake to use kWh when we could be using mJ instead, which I think is probably something close to the point Randall may have been trying to make. Anyway, I wasn't sure if there was a place for any of this random trivia in the article itself, but feel free to use it. [[User:Equites|Equites]] ([[User talk:Equites|talk]]) 17:11, 15 January 2025 (UTC)
: No!. TF?. ms is meter times seconds, m/s is meter per second. There is NOTHING wrong with kWh, it literally means kW times hours, and CANNOT mean anything else. kW per hour would be kW/h.. [[Special:Contributions/172.71.160.34|172.71.160.34]] 12:41, 16 January 2025 (UTC)
:: Technically, the SI would have you write m s for meter-seconds and ms for milliseconds. Thus, similarly, it should be kW h for kilowatt-hours, not kWh. It is unambiguous either way, but the standard is the standard. But that is a totally bizarre thing to get hung up on. Also, Equites's suggestion to use millijoules instead was maybe not well thought-out. [[Special:Contributions/172.68.15.234|172.68.15.234]] 17:45, 16 January 2025 (UTC)

Relevant XKCD… I mean relevant YouTube video: "Cursed units" 1 and 2: https://www.youtube.com/watch?v=kkfIXUjkYqE https://www.youtube.com/watch?v=Zg7xe8MkJHs [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 17:31, 15 January 2025 (UTC)

: Highly relevant, in fact. The first video referred to the kilowatt-hour as "cursed", which became a highly polarizing issue in the comments, something that was addressed at the beginning of part 2. Assuming these responses weren't cherry-picked, I get the impression that there are a lot of people on both sides of this. It seems like the same kind of thing we're seeing in this very comment section. [[User:ISaveXKCDpapers|ISaveXKCDpapers]] ([[User talk:ISaveXKCDpapers|talk]]) 18:10, 15 January 2025 (UTC)

I always wonder why people here prefer liter/m^2 for the amount of rain. Where the same number as mm is way easier to imagine. [[Special:Contributions/172.68.50.99|172.68.50.99]] 18:14, 15 January 2025 (UTC)
: At first, I was wondering if you would have rather had it in microliters/mm^2, but you meant the column height of the rain, like inches are used in the US. Along the line of L/m^2, something like mL/cm^2 might be nice considering the density of water, although the value also would be different by a factor. [[User:SammyChips|SammyChips]] ([[User talk:SammyChips|talk]]) 20:51, 15 January 2025 (UTC)
: That's the neat thing about the metric system, they are trivially simple to convert. 1l/m² is exactly 1mm. The fact that the meteorology uses the former just stems from the fact that that's how they measure it. The catch the rain on an area of 1m² into a beaker that contains some volume which is measured in liters. What annoys me though, is that noone seems to be talking about how terribly inefficient the fridge in the comic is. Mine only needs a tenth of the one that Whitehat tries to sell, and that's not even particularly good. --21:21, 15 January 2025 (UTC)
:: UK measurements, once it gets to weather reports/forecasts, tend to be in millimetres (or centimetres, where more for the layperson who don't need mm-resulution; or occasionally recast as 'old money' inches, with ''really'' bad rain events summarised in relation to whole feet), which is implicitly the depth to which ''any'' area would be filled (in a case where large catchment + funnelling valley situation is concerned, suffering from the run-off, might be ''reported'' as "equivalent to ''N'' feet of rain", down where the bad effects get concentrated, but this is not a meteorological measure as such).
:: Not sure I've ever seen volume/area as an end-result figure (might be relevent as an intermediate for measurement/calculation, especially when discussing the funelling effects of the given local geography), but of course it's trivially relatable.
:: Density of water would only figure in from replacing litres with kilogrammes (litres are 1/1000th of metres³ and any m² is 10,000 times the cm² (or millilitre), so a factor of 10 between L/m² and mL/cm²; divide L to mL by 1000, times m² to cm² by 10,000, => 10x) but I always find it useful to know that three 2L bottles of pop are (very close to, going by the nominal water content alone) 6kg... makes me feel better about lugging the weekly shopping home, where these might be the single most significant part of the weight. More usefully than cross-converting into length-cubed measure. ;) [[Special:Contributions/141.101.98.69|141.101.98.69]] 21:42, 15 January 2025 (UTC)

Isn't the point that KwH/day can be simplified to Watts (an average perhaps, but still) {{unsigned ip|162.158.41.72|21:24, 15 January 2025}}
: Yes, the joke seems pretty clearly about watts or kilowatts, not megajoules. Using megajoules doesn't result in any units being canceled; the denominator remains "/day". [[User:BatmanAoD|BatmanAoD]] ([[User talk:BatmanAoD|talk]]) 23:52, 15 January 2025 (UTC)

If the argument for kWh/day is that it's easy for the consumer to understand how it will affect their electricity bill – then kWh/month would be the right choice, because I doubt anyone receives an electricity bill every day. But the salesman prefers 3 kWh/day because it sounds like a smaller number than 90 kWh/month. And of course, if electricity bills were written in joules instead of illogical watt-hours, then MJ/month would be the easiest for the consumer. {{unsigned ip|162.158.134.90|22:31, 15 January 2025}}
:Per-month is tricky. You seem to assume month=30 days, when it can be 28-31 and is only 30 days a third of the time. Per quarter(-year) is a bit more consistent, less fractionally variant ''and'' closer to most utility bill frequencies as well, if you're looking for something not as eye-wateringly frightening as an annual estimate (which 'only' varies every 4.1237... years, on average). [[Special:Contributions/172.70.163.47|172.70.163.47]] 00:21, 16 January 2025 (UTC)
:: "''Per-month is tricky. You seem to assume month=30 days, when it can be 28-31...''" My electric bill for December 2024 is 33 days. The company closes the book when it is convenient, not per some calendar. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 05:22, 16 January 2025 (UTC)
:::Which is why electric consumption per month is even more tricky. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 06:33, 16 January 2025 (UTC)
:::It's still per some calendar. Just a calendar of the electric company, that you're not privy to.[[Special:Contributions/141.101.98.245|141.101.98.245]] 09:36, 16 January 2025 (UTC)
::It's an average. We're not talking specifically about February. You could multiply by 365.24/12 and get 91.31 kWh/month on average – but there's only one significant figure in 3 kWh/day. White Hat doesn't say 3.000 kWh/day. You have to round 91.31 to 90 to avoid false precision.
::The stated average is an estimate based on assumptions about how much you'll fill the fridge, how often you'll open the door, how long you'll leave the door open, the room temperature in your kitchen, how much surrounding cabinets will restrict air flow across the condenser, et cetera. The combined uncertainties make it meaningless to state a highly precise power consumption. The length of the month is just one of many sources of variation. [[Special:Contributions/162.158.134.90|162.158.134.90]] 10:40, 16 January 2025 (UTC)
:::Ahem... "multiply by 365.24'''25'''/12". As anyone with a fridge at least 125-years-old would appreciate... ;) [[Special:Contributions/141.101.98.178|141.101.98.178]] 12:23, 16 January 2025 (UTC)

I suspect this comic is inspired by the much more common pet peeve of incorrect/nonsensical units, frequently encountered in similar contexts. I'm so used to hearing kWh mistakenly written simply as kW, that I initially misread and assumed that's what the comic is about. That's a particularly common example, where you'll hear battery capacities listed in kW, or instantaneous power described in watt-hours. [[User:PotatoGod|PotatoGod]] ([[User talk:PotatoGod|talk]]) 09:53, 16 January 2025 (UTC)
:{{w|Calorie#Chemistry and physics|Calories}} vs. {{w|Calorie#Nutrition|calories}}, also... ;) [[Special:Contributions/141.101.98.178|141.101.98.178]] 12:23, 16 January 2025 (UTC)
: Yeah, get it straight people! Instantaneous battery discharge rate should be in some scale of watt-hours per second :P All this hassle because apparently nobody likes Joules or Coulombs as a unit. Besides the obvious unit cancelation thing, why would kilowatt-hours be more of a thing than watt-seconds anyway, since they are the same general order of magnitude? SammyChips 16:05, 17 January 2025 (UTC)

It could be worse.. I keep seeing TVs marked in kWh per 1000 hours... That is just insanity pure and simple.. It is in fact Watts!!![[Special:Contributions/172.71.160.34|172.71.160.34]] 12:38, 16 January 2025 (UTC)
:This is even some kind of a "standard", officially. See first image in here: https://ec.europa.eu/commission/presscorner/detail/en/ip_21_4484
:Also, world power consumption is almost exclusively represented in TWh per year, because TW is obviously not a thing. [[Special:Contributions/172.68.50.6|172.68.50.6]] 13:42, 16 January 2025 (UTC)
:That whole kerfluffle is mentioned in the "Cursed Units 2" video linked above. [[User:AdmiralMemo|Admiral Memo]] ([[User talk:AdmiralMemo|talk]]) 01:58, 17 January 2025 (UTC)

Can I be the obnoxious arse that points out that a 125W fridge will NOT be pulling 3kWh (or 3 units?) per day? Fridges run a compressor which makes the cold happen (via science and magic) and when there's enough cold in the box, it'll click off until cold is lacking. The durations will depend on ambient temperature, however observing my (oldish) fridge, it seems to run for about fifty seconds every four or five minutes.
[[Special:Contributions/141.101.69.92|141.101.69.92]] 18:45, 16 January 2025 (UTC)
:Fridge is actually heating device: it heats up your kitchen by pumping the heat from inside to outside. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 22:32, 16 January 2025 (UTC)

There is actually a good reason to differentiate between Wh/h (energy over time) and W (power): Non-constant consumption. If the fridge consumes 3kWh/d, its compressor will be rated in the 300-400W nominal range (the thermostatic controller will cycle the compressor on and off; for a modern fridge-freezer combination, a typical duty cycle would be in the 25-30% range). The unit nameplate will say "400W" because that's the rated power the electrical installation will have to be designed for (how many of these fridges can you put on a 20A breaker etc.). This is only determined by the physical properties of the compressor motor. The energy consumption additionally depends on insulation, internal space of the cabinet etc. etc. and only makes sense as a time average (due to the intermittent operation of the compressor). Not sure about US rules, but here in Europe, there's a standard energy class label for fridges which specifies kWh/a as a primary means of comparison. (Averaging over a year has the advantage that you can test against a standardized profile of ambient temperature change between summer and winter).
[[User:Ogehrke|Ogehrke]] ([[User talk:Ogehrke|talk]]) 21:28, 16 January 2025 (UTC)

The explanation incorrectly states that fuel efficiency in the metric system is measured in km/l. It's not. It's measured in l/km, so it reduces to area, not 1/area.[[Special:Contributions/172.71.182.77|172.71.182.77]] 22:40, 16 January 2025 (UTC)
:I recall seeing a book in my youth about "understanding units" that included great things like viscosity and explanations for why E=mc² cancels units properly. But they got to gasoline consumption, and used the analogy that the "area" represented here is the equivalent of the area of an adjacent trough of gas that would have to be scooped up by your car to keep it running. Very interesting way of illustrating unit cancellation. [[User:RandalSchwartz|RandalSchwartz]] ([[User talk:RandalSchwartz|talk]]) 23:05, 16 January 2025 (UTC)

Am I the only one bothered by the low ceiling? I hate rooms where I can't stretch without bumping. I had to come here to make sure I hadn't miscalculated the ceiling height. [[User:DougM|DougM]] ([[User talk:DougM|talk]]) 00:21, 17 January 2025 (UTC)
:Just assume that Cueball is using british gallons to further mess with the units. As the explanation that makes the room 2.44m which is a pretty standard - although still not very high - room height. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 06:29, 17 January 2025 (UTC)

Isn't there a joke about the salesman as well? Maybe I'm thinking too european, but kWh x 365 days = 1095 kWh/year seems ridiculously high to me. {{unsigned ip|172.70.247.41|12:10, 17 January 2025}}

German weather forecasts report rain as liters per square meter instead of millimeters. --[[Special:Contributions/172.69.109.87|172.69.109.87]] 12:55, 17 January 2025 (UTC)

re "there are cases where uncancelled units can be helpful to understanding the concept", something about mixing ratios could be added. E.g. 10g/kg and 10mL/L are both 1% ratios, but expressing them as uncancelled makes it clear that one is a ratio by mass and one is a ratio by volume. [[Special:Contributions/172.70.208.76|172.70.208.76]] 21:12, 17 January 2025 (UTC)