Here in my hotel room, high above Barcelona, I woke up. It was still dark outside, so I looked to my phone – sitting in its charging cradle – as a bedside clock. It told me that the
time was 02:30 (01:30 back home), and that the sun would rise at 07:17.
But how long would it be, until then?
Daylight savings time is harmonised across Europe by EU Directive 2000/84/EC1, but for all the good this harmonisation achieves it does not
perfectly remove every ambiguity from questions like this. That it’s 02:30 doesn’t by itself tell me whether or not tonight’s daylight savings change has been applied!
It could be 00:30 UTC, and still half an hour until the clocks go back, or it could be 01:30 UTC, and the clocks went back half an hour ago. I exist in the “hour of uncertainty”, a
brief period that happens once every year2. Right now, I don’t know what time it is.
I remember when it first started to become commonplace to expect digital devices to change their clocks twice a year on your behalf. You’d boot your PC on a morning and it’d pop up a
dialog box to let you know what it had done: a helpful affordance that existed primarily, I assume, to discourage you from making the exact same change yourself, duplicating the effort
and multiplying the problem. Once, I stayed up late on last Saturday in March to see what happened if the computer was running at the time, and sure enough, the helpful popup
appeared as the clocks leapt forward, skipping over sixty minutes in an instant, keeping them like leftovers to be gorged upon later.
Computers don’t do that for us anymore. They still change their clocks, but they do it silently, thanklessly, while we sleep, and we generally don’t give it a second thought.
That helpful dialog that computers used to have had a secondary purpose. Maybe we should bring it back. Not as a popup – heaven knows we’ve got enough of those – but just a subtle
subtext at the bottom of the clock screens on our phones. “Daylight savings: clock will change in 30 minutes” or “Daylight savings: clock changed 30 minutes ago”. Such a message could
appear for, say, six hours or so before and after our strange biannual ritual, and we might find ourselves more-aware as a result.
Of course, I suppose I could have added UTC to my world clock. Collapsed the waveform. Dispelled the ambiguity. Or just allowed myself to doze off and let the unsleeping computers do
their thing while I rested. But instead I typed this, watching as the clock reached 02:59 and then to 02:00. I’d started writing during summertime; I’d finished after it ended, a few
minutes… earlier?
Take a look at the map below. I’m the pink pin here in Oxfordshire. The green pins are my immediate team – the people I work with on a
day-to-day basis – and the blue pins are people outside of my immediate team but in its parent team (Automattic’s org chart is a bit like a fractal).
I’m the pink pin; my immediate team are the green pins. People elsewhere in our parent team are the blue pins. Some pins represent multiple people.
Thinking about timezones, there are two big benefits to being where I am:
I’m in the median timezone, which makes times that are suitable-for-everybody pretty convenient for me (I have a lot of lunchtime/early-afternoon meetings where I get to
watch the sun rise and set, simultaneously, through my teammates’ windows).
I’m West of the mean timezone, which means that most of my immediate coworkers start their day before me so I’m unlikely to start my day blocked by anything I’m waiting on.
(Of course, this privilege is in itself a side-effect of living close to the meridian, whose arbitrary location owes a lot to British naval and political clout in the 19th century: had
France and Latin American countries gotten their way the prime median would have probably cut through the Atlantic or Pacific oceans.)
2. Language Privilege
English is Automattic’s first language (followed perhaps by PHP and Javascript!), not one of the 120 other languages spoken
by Automatticians. That’s somewhat a consequence of the first language of its founders and the language in which the keywords of most programming languages occur.
It’s also a side-effect of how widely English is spoken, which in comes from (a) British colonialism and (b) the USA using
Hollywood etc. to try to score a cultural victory.
Languages self-reportedly spoken by Automatticians, sized proportional to the number of speakers. No interpretation/filtering has been done, so you’ll see multiple dialects of the
same root language.
I’ve long been a fan of the concept of an international axillary language but I appreciate that’s an idealistic dream whose war
has probably already been lost.
For now, then, I benefit from being able to think, speak, and write in my first language all day, every day, and not have the experience of e.g. my two Indonesian colleagues who
routinely speak English to one another rather than their shared tongue, just for the benefit of the rest of us in the room!
3. Passport Privilege
Despite the efforts of my government these last few years to isolate us from the world stage, a British passport holds an incredible amount of power, ranking fifth or sixth in the world depending on whose passport index you
follow. Compared to many of my colleagues, I can enjoy visa-free and/or low-effort travel to a wider diversity of destinations.
Normally I might show you a map here, but everything’s a bit screwed by COVID-19, which still bars me from travelling to many
places around the globe, but as restrictions start to lift my team have begun talking about our next in-person meetup, something we haven’t done since I first started when I met up with my colleagues in Cape Town and got
assaulted by a penguin.
But even looking back to that trip, I recall the difficulties faced by colleagues who e.g. had to travel to a different country in order tom find an embassy just to apply for the visa
they’d eventually need to travel to the meetup destination. If you’re not a holder of a privileged passport, international travel can be a lot harder, and I’ve definitely taken that for
granted in the past.
I’m going to try to be more conscious of these privileges in my industry.
This weekend, while investigating a bug in some code that generates iCalendar (ICS) feeds, I learned about a weird quirk in the Republic of Ireland’s timezone. It’s such a strange thing (and has so little impact on
everyday life) that I imagine that even most Irish people don’t even know about it, but it’s important enough that it can easily introduce bugs into the way that computer calendars
communicate:
Most of Europe put their clocks forward in Summer, but the Republic of Ireland instead put their clocks backward in Winter.
If that sounds to you like the same thing said two different ways – or the set-up to a joke! – read on:
The timezones of Europe look pretty simple compared to some parts of the world, but the illustration of the British Isles hides an interesting eccentricity.
A Brief History of Time (in Ireland)
Spring forward, fall back… just a little bit back, though. Not too much.
After high-speed (rail) travel made mean solar timekeeping problematic, Great Britain in 1880 standardised on Greenwich Mean Time (UTC+0) as the time throughout the island, and Ireland
standardised on Dublin Mean Time (UTC-00:25:21). If you took a ferry from Liverpool to Dublin towards the end of the
19th century you’d have to put your watch back by about 25 minutes. With air travel not yet being a thing, countries didn’t yet feel the need to fixate on nice round offsets in the
region of one-hour (today, only a handful of regions retain UTC-offsets of half or quarter hours).
That’s all fine in peacetime, but by the First World War and especially following the Easter Rising, the British government decided that it was getting too tricky for their telegraph
operators (many of whom operated out of Ireland, which provided an important junction for transatlantic traffic) to be on a different time to London.
It’s widely believed that the world’s first “U UP? [STOP]” message never got a response as a direct result of Anglo-Irish timezone confusion.
So the Time (Ireland) Act 1916 was passed, putting Ireland on Greenwich Mean Time. Ireland put her clocks back by 35 minutes and synched-up with the rest of the British Isles.
And from then on, everything was simple and because nothing ever went wrong in Ireland as a result of the way it was governed by by Britain, nobody ever had to think about the question of
timezones on the island again.
Ah. Hmm.
“Those Irish people want to govern their own country, do they? After we so kindly shared our king with them? Right-ho: let’s set fire to their cities and see how
they feel then.”
Following Irish independence, the keeping of time carried on in much the same way for a long while, which will doubtless have been convenient for families spread across the Northern
Irish border. But then came the Second World War.
Summers in the 1940s saw Churchill introduce Double Summer Time which he believed
would give the UK more daylight, saving energy that might otherwise be used for lighting and increasing production of war materiel.
Ireland considered using the emergency powers they’d put in place to do the same, as a fuel saving measure… but ultimately didn’t. This was possibly
because aligning her time with Britain might be seen as undermining her neutrality, but was more likely because the government saw that such a measure wouldn’t actually have much impact
on fuel use (it certainly didn’t in Britain). Whatever the reason, though, Britain and Northern Ireland were again out-of-sync with one another until the war ended.
I like to imagine that the development of powerful computers by the folks at Bletchley Park was a result of needing to keep track of timezones across the British Isles.
From 1968 to 1971 Britain experimented with “British Standard Time” – putting the clocks forward in
Summer once, to UTC+1, and then leaving them there for three years. This worked pretty well except if you were Scottish in which case you’ll have found winter mornings to be even
gloomier than you were used to, which was already pretty gloomy. Conveniently: during much of this period Ireland was also on UTC+1, but in their case it was part of a
different experiment. Ireland were working on joining the European Economic Community, and aligning themselves with “Paris time” year-round was an unnecessary concession but an
interesting idea.
But here’s where the quirk appears: the Standard Time Act 1968, which made UTC+1 the “standard” timezone
for the Republic of Ireland, was not repealed and is still in effect. Ireland could have started over in 1971 with a new rule that made UTC+0 the standard and added a “Summer
Time” alternative during which the clocks are put forward… but instead the Standard Time (Amendment) Act
1971 left UTC+1 as Ireland’s standard timezone and added a “Winter Time” alternative during which the clocks are put back.
It all seems so simple until you actually think about it.
(For a deeper look at the legal history of time in the UK and Ireland, see this timeline. Certainly don’t get all your
history lessons from me.)
So what?
You might rightly be thinking: so what! Having a standard time of UTC+0 and going forward for the Summer (like the UK), is functionally-equivalent to having a standard time of UTC+1 and
going backwards in the Winter, like Ireland, right? It’s certainly true that, at any given moment, a clock in London and a clock in Dublin should show the same time. So why would
anybody care?
This code for Europe/Dublin, from the Perl module Data::ICal::TimeZone, is technically-incorrect
because it states that the winter time is the standard and daylight savings of +1 hour apply in the summer, rather than the opposite.
But declaring which is “standard” is important when you’re dealing with computers. If, for example, you run a volunteer rota management
system that supports a helpline charity that has branches in both the UK and Ireland, then it might really matter that the
computer systems involved know what each other mean when they talk about specific times.
The author of an iCalendar file can choose to embed timezone information to explain what, in that file, a particular timezone means. That timezone information might
say, for example, “When I say ‘Europe/Dublin’, I mean UTC+1, or UTC+0 in the winter.” Or it might say – like the code above! – “When I say ‘Europe/Dublin’, I mean UTC+0, or UTC+1 in the
summer.” Both of these declarations would be technically-valid and could be made to work, although only the first one would be strictly correct in accordance with the law.
But if you don’t include timezone information in your iCalendar file, you’re relying on the feed subscriber’s computer (e.g. their calendar software) to make a sensible
interpretation.. And that’s where you run into trouble. Because in cases like Ireland, for which the standard is one thing but is commonly-understood to be something different, there’s
a real risk that the way your system interprets and encodes time won’t necessarily be the same as the way somebody else’s does.
If I say I’ll meet you at 12:00 on 1 January, in Ireland, you rightly need to know whether I’m talking about 12:00 in Irish “standard” time (i.e. 11:00, because daylight savings are in
effect) or 12:00 in local-time-at-the-time-of-the-meeting (i.e. 12:00). Humans usually mean the latter because we think in terms of local time, but when your international computer
system needs to make sure that people are on a shift at the same time, but in different timezones, it needs to be very clear what exactly it means!
And when your daylight savings works “backwards” compared to everybody else’s… that’s sure to make a developer somewhere cry. And, possibly, blog about your weird legislation.
Just when you think you’ve got them figured out (and the application you’re working on is coping correctly with daylight saving time), something comes along and blows your little mind. Like this, for example:
Suppose you’re chilling out in Hawaii on some lazy Sunday. Cocktail in hand, you check your
watch – it’s midday. Midday on Sunday – that means you’ve got a ‘plane to catch: you’re about to fly due South to the research station on Palmyra Atoll, part of the Line Islands. Palmyra Atoll, like Hawaii, is part of the United States, so you don’t even need your passport, but you pause for a moment
to try to work out whether you need to adjust your watch…
A timezone map of the mid-Pacific Ocean, showing the islands in question.
When it’s midday on Sunday in Hawaii, what time is it in Palmyra Atoll (which is at essentially the same longitude)?
It’s midday… on Monday! The Line Islands are uniquely considered to be in the timezone UTC+14:00 (and Hawaii is in UTC-10:00), so despite the fact that the Line Islands are, on the whole, East of the Hawaiian islands, the whole cluster of
them are an entire day ahead of Hawaii. Even those which are managed by the U.S. are closer to New Zealand (chronologically) than they are to any other U.S. terrirory (even though
they’re more distant geographically). It’s no wonder people get confused by things like the International Date Line – Magellan was apparently so confused by the fact that his ship’s log was a day out upon his return from a round-the-world trip that
he wrote a letter to the Pope about
the oddity.
Similarly, when the sun rises on the Line Islands, it marks the beginning of the day after the date that it rises on Hawaii, ten minutes later.
I find this particular quirk even more interesting than the similar one on the Diomede Islands (a pair of islands in the Bering Strait), sometimes called “Tomorrow Island” and “Yesterday Island”. The Diomedes are
clearly separated in an East-West configuration, whereas the Line Islands are clearly to the South (and North) of islands which are still stuck in “yesterday”.
The Diomede Islands
In practice, apparently, the 4 – 20 scientists living at any given time on Palmyra Atoll work at UTC-11:00: only an hour from Hawaii – presumably so that they maximise the period that their work week lines up with that in the
rest of the United States: but this only serves to exaggerate the phenomena: this means that you can hop from, say, Palmyra Atoll to nearby Teraina (population 1,155, about 150 miles away) and have to wind your watch forward by a massive 25 hours (or just one hour, I suppose).
By the time you’re living on a South Pacific island paradise, I suppose these things don’t matter so much.
