The Unimpressed Sun

Yesterday, Politico reported that US president Donald Trump had urged Arkansans to call their senator, Tom Cotton, and ask him to support a bill making daylight saving time (DST) permanent. One reason he gave is golf: the PGA Tour wants more afternoon light for its tournaments. Cotton objected that the US had already tried permanent DST and abandoned it after winter brought »absurdly late sunrises«.¹ Two politicians arguing about whether to keep the clocks forward, while the sun remained entirely unimpressed.

We designed the clock to fit the world. Somewhere along the way, we started designing the world to fit the clock.

Cotton has a point. In 1974, the United States tried keeping DST all year round, and dropped it within a year after children started walking to school in the dark.² But the argument hides a stranger fact. In Stockholm, where I live – and where children walk to school in the dark every winter – the sun rises as early as 03:31 in June and as late as 08:46 in December.³ Sweden and the United States both respond by moving the clocks forward one hour in spring and back one hour in autumn: a single jump to deal with a swing of more than five hours.

But the middle of the day hardly moves. If the clocks never changed, the sun would stand highest within about half an hour of 12:00 all year.⁴ The day stretches and shrinks around that fixed midpoint. Moving the clocks cannot lengthen a winter day; it only slides the whole day earlier or later.

So why do it? That depends on who you ask. Evening light suits golfers and anyone heading home after work; morning light suits schoolchildren, farmers, and other early risers. Energy savings? The jury’s out: studies have found small savings and small increases in use.⁵ Safety cuts both ways: dark mornings are dangerous for children, dark evenings are dangerous for drivers (in the US, collisions with deer are fourteen times more likely two hours after sunset than two hours before it⁶). DST is a trade: it takes light from the morning and gives it to the evening, and twice a year we argue about whether that’s a good deal.

We also treat the time on the clock as a fact, but it’s not. Solar noon is something that happens in the sky; 14:37 is something we agreed. Towns kept their own local times until the railways made standard time necessary, and as late as 1873, Japan divided the time from sunrise to sunset into six equal parts, and the night into six more. In summer, when the sun was up longer, each daytime hour got longer; in winter it got shorter. Clockmakers built adjustable dials to keep up.⁷ Timekeeping is such a successful invention that it has become invisible. We forget we made it up.

A clock has at least three jobs. We ask a single number to tell us the time, the position of the sun, and our place in our own day. Imagine instead a hypothetical watch with three dials. The Zulu dial (the pilots’ term for Coordinated Universal Time, UTC) is identical across the globe, so we can set up a meeting or catch a flight. The Solar dial tells us where the local day stands relative to the sun, dividing the daylight as those old Japanese clocks did. The Biological dial tells us where we are in our own day, because a late chronotype and an early riser in the same town actually live in different times.

A school could then say that in winter it starts at +1 Solar: one hour after sunrise, instead of, say, 08:30. That sounds confusing at first: which clock am I looking at? People felt the same about railway time. But it turns a start time into a variable that can be tested. A meeting still has a Zulu instant, perhaps found by intelligent calendars negotiating between attendees’ windows. A workplace could offer early risers and late chronotypes different biological work schedules.

Someone still has to decide how closely a school follows the sun. That argument would remain political, but the variable would be visible rather than hidden inside a number that everyone pretends is natural. And not everything should be individually timed: weekends, holidays and public ceremonies are valuable because we do them together in synchrony.

Trump and Cotton are arguing about an hour. But the sun doesn’t care what an hour is. It rises, crosses the sky, and sets. We are the ones who decided to cut that movement into pieces, name them, number them, and make everyone agree on them.

Maybe the three-dial watch is a good idea. Maybe it’s horrible. We don’t know, because we haven’t tried it. What we do know is that we’ve almost stopped designing time. We inherit its machinery, adjust it by an hour twice a year, and argue about the settings. We designed the clock to fit the world. Somewhere along the way, we started designing the world to fit the clock. The time has come to remake time.

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