NavList:

Time zones: Why humans can't stop tinkering with time

Happy New Year! Whether you spent the holiday reveling or relaxing, chances are good that you thought about time zones for a moment. After all, this is an international holiday predicated on staring at a clock. On no other regular occasion is the relentless ticking away of time united with glitter.

This ad hoc scheduling of an entire planet, which began with the modern age of globalization, is a messy miracle: After thousands of years of living on local solar time, it took humans less than 200 to coordinate billions of people down to the second.

But navigating time zones with relative ease doesn’t mean we’re done messing with them. States in the Northeastern US are flirting with moving into a new time zone. India is considering adding another. Spaniards have been debating a time-zone shift that would, for better or worse, disrupt a famous way of life. The tinkering will likely continue to eternity, unless we go all out and create the temporal equivalent of Esperanto.

By the digits
39: Number of time zones in the world
17: Number of time zones offset from Coordinated Universal Time by intervals of 30 or 45 minutes
40%: Share of the world’s population that lives in the eight countries operating under their own time zones, instead of Coordinated Universal Time
3.5 hours: The biggest time zone gain/loss (outside the International Date Line), along the 47-mile (76-km) border between Afghanistan and China
15 minutes: Offset between India (UTC +5.5) and Nepal (UTC +5.75)
27: Leap seconds that have been added to UTC since 1972, in order to synchronize atomic clocks to the Earth’s slowing rotation
$59 million: Money saved from decreased robberies by the 2007 daylight savings time extension

Origin Story

The zero hour

The adoption of time zones was made easier by establishing a benchmark: Greenwich Mean Time. In the 1670s, British astronomer John Flamsteed was employed at the Royal Observatory in Greenwich Park in London, where he figured out how to convert the apparent solar time (what you would see on a sundial, which results in days of inconsistent length) to mean solar time (which assumes a fictional sun that moves at a uniform rate). His catalog of stars was set to GMT, which became crucially important as the UK became a modern naval power. GMT has since given way to Coordinated Universal Time (or UTC), but UTC is basically GMT, and all time zones are relative to the prime meridian in Greenwich, where it all began.

Timeline

1840: Britain’s Great Western Railway adopts a standard time at all stations. Seven years later, all British stations start running on Greenwich Mean Time. By 1880, Britain adopted it nationwide.

1883: Many railroads and governments adopt the General Time Convention, which divided the United States and Canada into five time zones.

1884: Twelve nations agree to use GMT as the international basis for time zones at the International Prime Meridian Conference.

1912: The newly created Republic of China adopts five time zones.

1918: President Woodrow Wilson makes four US time zones official with the Standard Time Act.

1947: Newly independent India adopts a single time zone.

1949: The new communist government collapses China’s five time zones into one.

1960: The International Radio Consultative Committee formalizes the concept of UTC, with time synchronized using atomic clocks. (The acronym is a compromise between England and France.)

2011: Dmitry Medvedev cuts Russia’s time zones from 11 to nine. Also, Samoa skipped a Friday in order to switch sides of the International Date Line.

2014: Vladimir Putin increases Russia’s time zones from nine to 11.

The International Date Line lies roughly on the 180th meridian, halfway around the world from the Greenwich Meridian. But it’s actually a wild zigzag: Here’s why.

Quotable
“Modern life, our system of education founded on the requirements of punctuality, scholastic exercises on the charts of train schedules, geographic maps—all this inculcates in us, from childhood, a very Newtonian idea of space and time. This is why we have such difficulty perceiving the absurdity of questions such as ‘What lies beyond the limits of the universe?’”
—Rémy Lestienne

Pop Quiz
What hobby inspired the creation of daylight savings time?
Bug hunting - Shopping - Baseball - Golf

Correct. New Zealand postal worker George Vernon Hudson wanted more time to pursue entomology after work.

Incorrect. But fans enjoyed it.

If your inbox doesn’t support this quiz, find the solution at bottom of email.

Time zones before time zones

Before the world’s time got sliced into (mostly) easy pieces, how did people manage to keep things straight? It was confusing but not completely willy-nilly. Because apparent solar time is relatively systematic, different local times could still be charted out relative to one another. The resulting concentric rings of time gorgeously capture the complications of the pre-time zone era.

A little list
Time is politics
Not all time-zone changes are grounded in logistics:
Spain switched from GMT to Central European Time in 1941, a gesture of solidarity from Francisco Franco to Adolf Hitler.
When Crimea voted to join Russia in 2014, it also moved its clocks two hours ahead to join Moscow’s time zone.
In 2015, North Korea adopted Pyongyang Time, setting clocks back half an hour to reflect the time before Japanese colonization.

Want to work some time-zone arbitrage? Researchers investigating the economic returns of more sleep looked at the cities of Huntsville, Alabama and Amarillo, Texas, which are close together but in different time zones. The sun goes down an hour later in Amarillo, so residents go to bed later there—and the economists found that, as a result, similar populations in Huntsville have incomes that are 4.5% higher.

It's complicated
What time is it in Antarctica?

Antarctica lies on every line of longitude, but time is funny there: Even regions that lie along the same meridian don’t necessarily observe the same time. Time zones are based on territorial claims, but even within that, it gets messy. Stations might use the time of the country that owns them or the time of their supply base. To simplify, some places simply (marked in red) just observe Coordinated Universal Time.

Matters of debate
How many time zones do we need, really?