From 555b7304d366ca4b140e2fc2dbb4887634c9ac57 Mon Sep 17 00:00:00 2001 From: Ryan Fox Date: Mon, 3 May 2021 04:13:03 +0000 Subject: [PATCH] Blog: Add Time rant --- posts/2021-05-03-time-rant.md | 88 +++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 posts/2021-05-03-time-rant.md diff --git a/posts/2021-05-03-time-rant.md b/posts/2021-05-03-time-rant.md new file mode 100644 index 0000000..3f28b0b --- /dev/null +++ b/posts/2021-05-03-time-rant.md @@ -0,0 +1,88 @@ +template: post +title: Time rant +author: flewkey +timestamp: 1620014860 +license: CC-BY + +Bob wants to talk to a group of people who live in different areas. What time +standard should Bob use to schedule the call? How about +[Coordinated Universal Time](https://en.wikipedia.org/wiki/Coordinated_Universal_Time) +(UTC)? It is the internationally agreed upon standard for world time, so Bob +should be able to use it, right? + +Unfortunately, life is not so simple. If Bob scheduled a call for “05:00 UTC”, +one other person would show up on-time. The rest will try to join at 17:00 +(05:00 p.m.) in whatever their local time zone is. This insanity is the reason +why [countdown timers](https://www.timeanddate.com/countdown/create) +are so common nowadays. + + + +This insanity has been driving people insane since the beginning of time, but +this is not the fault of individual people who don’t understand what “UTC” is. +This is a systemic issue which ought to be corrected. If everybody learns to +read analog clocks in primary school, they should learn about time zones as +well. + +--- + +### 12-hour time and 24-hour time + +In 12-hour time, the clock wraps around every 12 hours, dividing the day into +two periods: “a.m.” and “p.m.”. This is terrible, as it creates ambiguity +when most people and clocks tell the time. The number “12” is also used in +place of the number “0” for some reason, going against how numbers usually +wrap around. Seeing 12-hour time on a digital clock makes me feel nauseous. + +In 24-hour time, the clock wraps around every 24 hours, once per day. That’s all +there is to it. + +#### To convert 12-hour time to 24-hour time: + +1. Add 12 hours if it is “p.m.” +2. If the hours column is equal to 24, set it back to 0 + +#### To convert 24-hour time to 12-hour time: + +1. Subtract 12 hours if it is 13:00 or greater +2. If the hours column is equal to 0, set it to 12 + +--- + +### Time zones 101 + +A time zone is just an area that follows a time standard. However, if computers +all synced to different time standards depending on the region, that would be +terrible. Instead, most of them sync to Coordinated Universal Time (UTC) +instead. Then, they apply a positive or negative offset to UTC before formatting +the time and displaying it to users. + +As far as most people should be concerned, offsets are just acronyms that +represent offsets from UTC. For example, [Central European Time](https://www.timeanddate.com/time/zones/cet) +(CET) is one hours ahead of UTC. This means that it is also represented as +UTC+1 or UTC+0100. Some time zones need more than an hour of precision as well. +For example, [Newfoundland Standard Time](https://www.timeanddate.com/time/zones/nst) +(NST) is represented as UTC-3:30 or UTC-0330. + +Look up your time zone on [this map](https://www.timeanddate.com/time/map/). +Memorize the acronym and UTC offset. Also understand that it will roll forward +by an hour when [Daylight Saving Time](https://www.nist.gov/pml/time-and-frequency-division/popular-links/daylight-saving-time-dst) +(summer time in Europe) applies. This will allow you to understand UTC time in +relation to your time zone. + +If you can remember the acronyms for other time zones, you will also be able to +convert between them in your head. This is a useful ability to have. +Some common time zones in North America worth remembering are +[Eastern Standard Time](https://www.timeanddate.com/time/zones/est) (UTC-5), +[Central Standard Time](https://www.timeanddate.com/time/zones/cst) (UTC-6) and +[Pacific Standard Time](https://www.timeanddate.com/time/zones/pst) (UTC-8). + +--- + +### Conclusion + +Those who made it to the end of this post can count themselves among the few +capable of reading time properly. If you thought time zones were interesting, +wait until you hear about timekeeping. The NIST has a +[great page](https://www.nist.gov/pml/time-and-frequency-division/time-services/utcnist-time-scale/how-utcnist-works) +describing how time standards are kept. The rabbit hole goes deep.