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The Problem with Time & Timezones - Computerphile

Computerphile

2.6M subscribers • 66 videos on Hallway

YouTube
  • Recommended by 14 people: 12 on Hacker News, 1 in engineering communities and 1 curated list.
  • A classic. People kept recommending it from 2014 to 2026.
  • Presented by Tom Scott

Beginner. No background in the topic needed.

4.3M views12 years ago14 recommendations

Tools and practiceDeveloper productivity

Tom Scott explains why handling time, timezones, and leap seconds in software is incredibly complex and prone to errors.

A web app that works out how many seconds ago something happened. How hard can coding that be? Tom Scott explains how time twists and turns like a twisty-turny thing. It's not to be trifled with! A Universe of Triangles: youtube.com/watch?v=KdyvizaygyY LZ Compression in Text: youtube.com/watch?v=goOa3DGezUA Characters, Symbols and the Unicode Miracle: youtube.com/watch?v=MijmeoH9LT4 More from Tom Scott: youtube.com/user/enyay and twitter.com/tomscott facebook.com/computerphile twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computerphile is a sister project to Brady Haran's Numberphile. See the full list of Brady's video projects at: bit.ly/bradychannels

Why it's here

14 people recommend this

What people say. Highly recommended as an entertaining and clear explanation of why programmers should never try to write their own timezone logic.

Moments people linked to

tehmacoon Hacker News • Recommends

On “A positive leap second will be introduced at the end of June 2015”

This will probably resonate with people here1. A brilliant video by Tom Scott for Computerphile, where he starts to explain what coding timezones correctly is like and by the end of it is in full polite-mini-rant-mode :D 1 link to this video
View on Hacker News

yborison Hacker News • Recommends

On “Timezone Bullshit”

Obligatory post to Computerphile episode about Timezones - a must watch for developers just starting out with Timezones link to this video
View on Hacker News

every-programmer-should-knowcurated list on GitHubRecommends

Under “Time”

:movie_camera: The Problem with Timezones
View the list

u/rschieferin r/dotnet • Recommends

The Problem with Time Timezones OR Why to use NodaTime
3View on Reddit

sk5ton Hacker News • Recommends

On “The Death and Life of the 13-Month Calendar”

An excellent video touching on some of the intractable aspects of our datetime-marking system's personality quirks: link to this video
View on Hacker News

myfonjon Hacker News • Recommends

On “How to save datetimes for future events”

There is a great (humorous) Computerphile video about this topic: "The Problem with Time & Timezones" 0 0 link to this video
View on Hacker News

zeta0134on Hacker News • Recommends

On “Time Zones Aren’t Offsets – Offsets Aren’t Time Zones”

Computerphile did an excellent overview of time zones and all their complexities in the context of programming: link to this video I was quite surprised by some of the stranger rules out there, especially the regions that chose to skip a day for whatever reason. Timezones are complex! Far, far more complex than simple offsets.
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wtfishackernewson Hacker News • Recommends

On “Time to Dump Time Zones”

>Just try to explain to everyday people just how hard the problem is A bit off topic but Computerphile / Tom Scott did an excellent video doing that link to this video
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psteinweberon Hacker News • Recommends

On “UTC Is Enough for Everyone, Right?”

I really enjoyed this. And I think no one mentioned the very related Computerphile video yet: "The Problem with Time & Timezones " link to this video Same topic, equally entertaining (not AS geeky though).
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enhdlesson Hacker News • Recommends

On “US Constitution – A Git repo with history of edits”

> such a reasonable, trivial task? Tom Scott has a pretty good video explaining exactly why writing code about time is not trivial: The Problem with Time & Timezones - Computerphile link to this video
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coder543on Hacker News • Recommends

On “Measuring Latency in Linux (2014)”

That’s a hard question regardless of programming language. One commonly referenced YouTube video about time that explains why this is hard: link to this video A reasonable first approximation of a solution would be to just check every second (or minute, or hour, depending on requirements) whether the current system time is later than the scheduled time for any pending events. Then you probably want to make sure events are marked as completed so they don’t fire again if the clock moves backwards. Trying to predict how many seconds to sleep between now and 3pm on Saturday is a difficult task, but you can probably use a time library to do that if it’s important enough... but what happens when the governme…
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jonathansampsonon Hacker News • Recommends

On “Goodbye Brave”

…tting up a timer, wound up scheduling numerous timers when our 'How long until tomorrow' code began returning negative numbers. That set of unintended timers locked-up the application itself. You can see our issue for the behavior here: link . For 10 minutes of anxiety, check out 'The Problem of Time & Timezones' from Tom Scott of Computerphile: link to this video . It's a fantastic summary of the issues programmers face when dealing with time :) Sampson (Brave Team)…
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birdman3131on Hacker News • Recommends

On “Australia's weird little time zone (2008)”

I have to toss this classic video on the issues with timezones and programming. The sheer amount of growing exasperation as the video goes is hilarious. link to this video The Problem with Time & Timezones - Computerphile / Tom Scott
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wolrahon Hacker News • Recommends

On “The surprising whimsy of the Time Zone Database”

That might work for the current form of the country-specific time zones officially acknowledged by countries that exist in TLD form, but the tz database contains many more current time zones more importantly piles of historical time zones. Representing just the historical forms of currently recognized time zones in DNS would be a mess, without even getting in to those that are not associated with a country that currently exists and has a TLD. edit: This is a great video explaining a lot of the reasons why time zones are nowhere close to as straightforward as you may think: link to this video
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u/Drach88in r/C_Programming • Mentions

On “GCC should warn about 2^16 and 2^32 and 2^64”

Thank you tremendously for sharing! Also: link to this video
3View on Reddit

SFJulieon Hacker News • Mentions

On “Maya – Python Datetimes for Humans”

…5) TZ are not versioned, if the TZ changed between 2 records you may have made, you have inaccurate intervals stored. We do NOT have an API to take TZ change over time in consideration. 6) CEST/DST is breaking the axiom that time is a growing monotonic function References 8.5.3 TZ in postgresql man link Computerphile what's wrong with timezones link to this video…
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