explain xkcd - User contributions [en]

2867: DateTime

2023-12-14T06:12:09Z

172.71.166.76: Undo revision 330748 by 172.71.166.76 (talk)

{{comic
| number = 2867
| date = December 13, 2023
| title = DateTime
| image = datetime_2x.png
| imagesize = 679x478px
| noexpand = true
| titletext = It's not just time zones and leap seconds. SI seconds on Earth are slower because of relativity, so there are time standards for space stuff (TCB, TGC) that use faster SI seconds than UTC/Unix time. T2 - T1 = [God doesn't know and the Devil isn't telling.]
}}

==Explanation==
{{incomplete|Created by a DATETIME SYSTEM BETWEEN T1 AND T2 - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

[[Ponytail]] asks [[Cueball]] how to calculate the time elapsed between two instants. A Cueball not intimately familiar with the complexities of the way humans measure time naively assumes that this is given by the difference of the timestamps. A Cueball who is familiar panics and states that it is impossible to know, and further that it is forbidden to even ask the question.

Some of these complexities include time zones (and changes to time zones), the international date line, daylight savings time and differing observation (or nonobservation) thereof in different areas (and changes to the observation of daylight savings time over time), leap days and leap seconds, etc. Another complexity is found in relativistic effects. A partial list of such minutia may be found at [https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca Falsehoods Programmers Believe About Time]. The title text of the comic also references some of them.

The statement that it is impossible to know and a sin to ask is obviously hyperbolic; it's an expression of the fact that determining the answer accurately can be complicated and programming systems that attempt to do this can be frustrating.

"T2 - T1 = [God doesn't know and the Devil isn't telling.]": This appears to allude to the expression "god only knows", suggesting that this is so unknowable that even god doesn't know. The idea that the Devil does know alludes to the "devilish" complexity and frustration associated with this problem.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Ponytail is talking to Cueball.]
:Ponytail: Event #1 happened at time T1.
:Cueball: Okay.

:Ponytail: Then event #2 happened at time T2.
:Cueball: Mhmm.

:Ponytail: How would you calculate how much time elapsed between T1 and T2?

:[The comic splits into two paths, each with a caption at the top.]

:[Path 1, upper right panel]
:Caption: Normal person:
:Cueball: T2 minus T1.

:[Path 2, lower right panel]
:Caption: Anyone who's worked on datetime systems:
:[Cueball has his arms raised.]
:Cueball: '''''It is impossible to know and a sin to ask!'''''

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Time]]

2867: DateTime

2023-12-14T06:08:32Z

172.71.166.76: /* Explanation */

{{comic
| number = 2867
| date = December 13, 2023
| title = DateTime
| image = datetime_2x.png
| imagesize = 679x478px
| noexpand = true
| titletext = It's not just time zones and leap seconds. SI seconds on Earth are slower because of relativity, so there are time standards for space stuff (TCB, TGC) that use faster SI seconds than UTC/Unix time. T2 - T1 = [God doesn't know and the Devil isn't telling.]
}}

==Explanation==
{{incomplete|Created by THREE AIS AND TWO NERDS. Do NOT delete this tag too soon.}}

[[Ponytail]] asks [[Cueball]] how to calculate the time elapsed between two instants. A Cueball not intimately familiar with the complexities of the way humans measure time naively assumes that this is given by the difference of the timestamps. A Cueball who is familiar panics and states that it is impossible to know, and further that it is forbidden to even ask the question.

Some of these complexities include time zones (and changes to time zones), the international date line, daylight savings time and differing observation (or nonobservation) thereof in different areas (and changes to the observation of daylight savings time over time), leap days and leap seconds, etc. Another complexity is found in relativistic effects. A partial list of such minutia may be found at [https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca Falsehoods Programmers Believe About Time]. The title text of the comic also references some of them.

The statement that it is impossible to know and a sin to ask is obviously hyperbolic; it's an expression of the fact that determining the answer accurately can be complicated and programming systems that attempt to do this can be frustrating.

"T2 - T1 = [God doesn't know and the Devil isn't telling.]": This appears to allude to the expression "god only knows", suggesting that this is so unknowable that even god doesn't know. The idea that the Devil does know alludes to the "devilish" complexity and frustration associated with this problem.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Ponytail is talking to Cueball.]
:Ponytail: Event #1 happened at time T1.
:Cueball: Okay.

:Ponytail: Then event #2 happened at time T2.
:Cueball: Mhmm.

:Ponytail: How would you calculate how much time elapsed between T1 and T2?

:[The comic splits into two paths, each with a caption at the top.]

:[Path 1, upper right panel]
:Caption: Normal person:
:Cueball: T2 minus T1.

:[Path 2, lower right panel]
:Caption: Anyone who's worked on datetime systems:
:[Cueball has his arms raised.]
:Cueball: '''''It is impossible to know and a sin to ask!'''''

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Time]]

2777: Noise Filter

2023-07-17T02:52:48Z

172.71.166.76: two minor grammar changes

{{comic
| number = 2777
| date = May 17, 2023
| title = Noise Filter
| image = noise_filter_2x.png
| imagesize = 298x345px
| noexpand = true
| titletext = Party Mode also enables the feature, but reverses the slider.
}}

==Explanation==
This comic portrays a generalized, minimalist version of a search engine's front end. The engine helps the user find things (in this case, restaurants) that conform to user preferences. Preferences shown are hours of opening, mean of review scores, price range, and current noise level. All but "current noise level" are rendered less prominent by being drawn in gray, with various typical choices applied; the exception being marked for the reader's attention with a red-circled (and arrowed) overlay. The user, setting the parameters for their search, adjusts the slider to select the maximum tolerable noise level. Taking the slider for increasing noise tolerance past 100 db is eventually interpreted as "Any", or limitless, whatever this might mean for any given position past 100 but not yet at Any. The high range ([https://hearinghealthfoundation.org/keeplistening/decibels the 'safe' noise threshold is 70 decibels or less]) tells us that the person designing the tool (Randall) may be accustomed to loud restaurants, probably including some [https://www.theatlantic.com/technology/archive/2018/11/how-restaurants-got-so-loud/576715/ that have been getting louder over time], or not actually that familiar and going only by a rough idea of what is necessary and possible.

The caption's statement that the noise slider should automatically appear when the user reaches the age of 30 (ignoring the privacy concerns implicit in such a function) plays on the common perception that a person's ability to tolerate background noise while dining (or anywhere else) deteriorates with age. Such declines have been documented, linked to changes in the inner ear and associated nerves with aging, and can occur in the absence of other hearing-loss symptoms. The term [https://www.frontiersin.org/articles/10.3389/fnagi.2022.890010/full "SPiN (Speech Perception in Noise) threshold"] has been conceived to measure this loss. Other studies suggest that [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918655/ personality traits and gender, as well as age], contribute to declines in the ability to perceive speech in noise, so the trope is less precise than is indicated here, and in advertisements by health providers for hearing loss treatments.

The title text shows that Randall imagines a "Party Mode" which also includes this filter, but reversed. Those younger than 30 may wish to filter out places that are too quiet and restrained and won't already have a 'party atmosphere' upon their arrival.

The criteria checked for some of the filter's options can be presumed to have been provided in advance by those running the restaurant (e.g. opening times, though perhaps derived indirectly from other web-listings promoting the business) or its customers (user ratings being aggregated from various online review sites), but the ''current'' noise levels will probably require some form of [https://thepihut.com/products/enviro-for-raspberry-pi real-time monitoring] installed in the premises, with or without the complicity/knowledge of the owners. [https://www.popsci.com/story/technology/restaurant-noise-levels-solutions/ Efforts are being made in this area], some of which suggest that a real-time measurement of overall noise won't be all that helpful to a restaurant patron, since the noise at a suitably-engineered table likely will differ significantly from the background.

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

:[A representation of web-page or app-screen contents. Except where mentioned otherwise, all lines and fills are in muted gray half-tones.]
:[At the top, a search bar with the standard magnifying glass symbol and a word entered into the text field:] Restaurants
:[Below that, a horizontal rule as a section header, with a titular label centered over it:] Filters

:[Subsection title:] Hours
:[Three buttons, horizontally:]
:[Button:] Any
:[Button, selected, drawn in light blue and infilled with lighter blue:] Open now
:[Button:] Open at…

:[Subsection title:] Rating
:[Five buttons, horizontally, four with explicit star-rating ranges:]
:[Button, selected, in blue:] Any
:[Button:] ☆3+
:[Button:] ☆3.5+
:[Button:] ☆4+
:[Button:] ☆4.5+

:[The following subsection, alone, is entirely circled in a drawn red circle, with an additional red arrow pointing to it, and is all in the unmuted tones.]
:[Subsection title:]
:Current Noise Level
:[A horizontal slider-bar, with six marked and labeled positions along its length.]
:[Mark:] 60dB
:[Mark:] 70dB
:[Mark:] 80dB
:[Mark:] 90dB
:[Mark:] 100dB
:[Mark:] Any
:[The bar's 'slider' control is positioned between the two central marks, at approximately 85 dB.]
:[The slider itself is drawn in blue, and the bar is shaded blue in the section between its far left and the slider element to show the range of selections.]

:[Subsection title:] Price
:[Four buttons, with multiple-selection, horizontally:]
:[Button, selected, in blue:] $
:[Button, selected, in blue:] $$
:[Button:] $$$
:[Button:] $$$$

:[Caption below the panel:]
:This feature should automatically appear when you reach age 30.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Internet]]
[[Category:Online reviews]]

Talk:2714: Cold Complaints

2022-12-21T22:32:32Z

172.71.166.76:

That study sounds like something that would win an Ig Nobel Prize. But the 2002 prize in medicine went to "Scrotal Asymmetry in Man and in Ancient Sculpture". [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 20:37, 21 December 2022 (UTC)

Also common cold cannot really be cured, just wait and see. http://www.picturequotes.com/proper-treatment-will-cure-a-cold-in-seven-days-but-left-to-itself-a-cold-will-hang-on-for-a-week-quote-272191 [[User:Vdm|Vdm]] ([[User talk:Vdm|talk]]) 20:49, 21 December 2022 (UTC)

Are we sure that's the actual explanation? I thought the panels we see of the telemedicine are fibs to explain why Harry is acting this way. As in, he's pretending a medical professional told him to act like this. [[Special:Contributions/172.69.68.13|172.69.68.13]] 21:59, 21 December 2022 (UTC)

Can the citation be moved to a ref tag instead of just Being There? on a related note, why is the 58 bolded? [[Special:Contributions/172.71.166.76|172.71.166.76]] 22:32, 21 December 2022 (UTC) [[NonUser:Bumpf]]

2659: Unreliable Connection

2022-12-17T11:02:04Z

172.71.166.76: Replaced content with "Dear, I came across explainxkcd.com and wanted to share this great free AI tool. With this tool, you write content 10 times faster and with much higher conversion rates...."

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