Editing 2867: DateTime

Jump to: navigation, search

Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.

The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision Your text
Line 10: Line 10:
  
 
==Explanation==
 
==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.
 
[[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.
 
 
−
Randall's use of the term "DateTime systems" covers [https://metacpan.org/pod/DateTime any] [https://docs.python.org/3/library/datetime.html number] [https://learn.microsoft.com/en-us/dotnet/api/system.datetime?view=net-8.0 of] [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date situations], and the complexities are hardly confined to any particular programming language, or indeed computers as a whole. Some of these complexities include time zones (and changes to time zones), the international date line, daylight saving time and differing observation (or non-observation) thereof in different areas (and changes to the observation of daylight saving time over time), leap days and leap seconds, etc.  Another complexity is found in relativistic effects, in which the flow of time varies depending on how deep in a gravity well one is; {{w|Barycentric Coordinate Time}} and {{w|Geocentric Coordinate Time}} (in French, TCB and TCG respectively - the reference to TGC in the title text appears to be a typo) are time systems used for space missions and orbit calculations that handle this and shortly after this comic was published it was announced that [https://www.space.com/white-house-nasa-time-zone-moon Coordinated Lunar Time (LTC)] would be established. A partial list of such minutiae 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. Depending on when T1 and T2 are, changes in calendar system may also be a relevant consideration—perhaps most famously, the change from the Julian calendar and the Gregorian calendar, two calendar systems which are nearly identical but nearly two weeks apart, and which different countries changed at different times.
+
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" is because Ponytail did not provide enough information in the question: She needed to specify the location and time zone of both observations, and possibly the exact values of T1 and T2 to the nanosecond.  Considering the restrictions imposed by relativity on two observers agreeing on the timing of events, it may be literally impossible to determine a value of T2 - T1 that is absolutely "correct" to arbitrary levels of precision.
+
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.
  
−
The addition of "and a sin to ask" is hyperbolic. It implies that asking such questions is akin to attempting to acquire forbidden knowledge of the nature of God or the Universe, for example, through practices such as {{w|Numerology}}, which some may consider heretical. 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.
−
 
 
−
"T2 - T1 = [God doesn't know and the Devil isn't telling.]": This is a colloquial expression that riffs on the more common "God only knows" as well as "Hell knows and Heaven suspects", to suggest that the thing in question is even more unknowable than the usual type of unknowable thing, to the point where it may be an evil invention of the Devil designed to cause complexity and frustration for the people having to deal with it.
 
  
 
==Transcript==
 
==Transcript==
 +
{{incomplete transcript|Do NOT delete this tag too soon.}}
 
:[Ponytail is talking to Cueball.]
 
:[Ponytail is talking to Cueball.]
 
:Ponytail: Event #1 happened at time T<sub>1</sub>.
 
:Ponytail: Event #1 happened at time T<sub>1</sub>.

Please note that all contributions to explain xkcd may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see explain xkcd:Copyrights for details). Do not submit copyrighted work without permission!

To protect the wiki against automated edit spam, we kindly ask you to solve the following CAPTCHA:

Cancel | Editing help (opens in new window)

Templates used on this page:

Retrieved from "https://www.explainxkcd.com/wiki/index.php/2867:_DateTime"