In computer systems, time is measured starting from some arbitrarily chosen point. That particular time is known as the "epoch" for that system. The UNIX operating system internally uses an epoch of January 1, 1970, and measures the time as a number of seconds from then. Since this was intended only for things internal to the OS (File last modified times and the like), using 1-Jan-1970 was safe as no UNIX systems existed before that date.
Dates before January 01, 1970 are represented by negative values. At 03:14:08 on January 19, 2038 the 32-bit versions of the Unix time stamp will cease to work, as it will overflow the largest value that can be held in a signed 32-bit number. The 64-bit version will expire at 15:30:08 December 4, 292,277,026,596.
Cueball has clearly misused the system date in some way, his friend makes a pun by combining "Epoch" with "Epic Fail" - a colloquial term meaning "a very big mistake was made".
The title text takes the joke to the next level, claiming that the entire universe began when Unix did, and therefore no one can be older than 38 (at the time of the comic). This is also similar to Last Thursdayism.
- [Cueball sits at a computer, staring at the screen and rubbing his chin in thought. A friend stands behind him.]
- Cueball: Weird - My code's crashing when given pre-1970 dates.
- Friend [pointing at the computer]: Epoch fail!
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That is why on Unix epoch (the time_t type) is signed type, and covers dates before epoch. --JakubNarebski (talk) 19:52, 5 July 2013 (UTC)
- Ohh, and much more is missing. I did mark it as incomplete. We also have to talk about the time frame the 32bit epoch does cover, and what would be changed by using a 64bit variable. What will happen on 19 January 2038?--Dgbrt (talk) 20:17, 5 July 2013 (UTC)
- The general hope, it appears, is that 64-bit integers will be firmly in place, having ousted the feeble 32-bit integers from the system time. As has been demonstrated in innumerable instances, it's rather difficult to eliminate legacy code from systems due to attempts to support older systems in a backward-compatible methodology. In short, however, it will take time to resolve time. Thokling (talk) 05:34, 22 September 2013 (UTC)
- I so look forward to seeing Epoch boom to hurriedly uplift 32 bit code before the 'end'. Similar to the Y2K boom. I might consider lending my expertise at a considerable markup. :) Puck0687 (talk) 17:57, 4 December 2015 (UTC)
- Rewrite needed
The current explanation barely has to do with the actual topic of the comic. Instead it explains several unrelated qualities of Unix time, and petty much skips over the actual epoch thing. Needs a rewrite.
--NeatNit 22.214.171.124 05:59, 8 February 2015 (UTC)
Why would anyone want to take the square root of a timestamp? It is much more likely that Cueballs program just handles negative time values incorrectly. Condor70 (talk) 07:15, 14 November 2016 (UTC)
- I agree, I changed the page to reflect that PotatoGod (talk) 03:33, 14 December 2017 (UTC)
http://coolepochcountdown.com/ links to this site saying that XKCD captured moment when Unix time counter reached 1234567890, so maybe this comic is released at that moment 126.96.36.199 (talk) (please sign your comments with ~~~~)
- No, that time would occur about a year from this comic's publication (13 February 2009 at 23:31:30 UTC). 607: 2038 was published 8 July 2009, which is about five months too late, and I have no idea how 543: Sierpinski Valentine had to do with Unix time. 188.8.131.52 22:34, 16 April 2019 (UTC)