EOY

Why time zones exist

For most of history every town kept its own time by the Sun. Time zones exist because the railway made that impossible, and one conference in Washington gave the world a zero line.

Sun time

Local mean solar time sets noon when the Sun is highest overhead, so towns to the east are always a little ahead of towns to the west — about four minutes for each degree of longitude. When the fastest thing on land was a horse, nobody noticed. A traveller reset a pocket watch on arrival.

The railway problem

A train timetable needs one clock. British railways adopted a single railway time in the 1840s. In North America the problem was worse: dozens of railroads, each running on the local time of its home city, published timetables that could not be reconciled. On 18 November 1883 the railroads adopted standard time zones one hour apart, and the towns along the lines followed.

Fleming and the conference

The Canadian engineer Sandford Fleming argued for a coordinated worldwide system rather than a patchwork of national ones. In October 1884, twenty-six countries sent forty-one delegates to the International Meridian Conference in Washington, D.C. The decisive vote — 22 in favour, one against (Santo Domingo), France and Brazil abstaining — adopted the meridian through the transit instrument at Greenwich Observatory as the initial meridian, and a universal day beginning at Greenwich mean midnight. What the conference did not do is often forgotten: it adopted no time zones. Delegates ruled that outside its scope, and countries introduced standard zones on their own timetables over the following decades.

From Greenwich Mean Time to UTC

Greenwich gave the world a zero line, and Greenwich Mean Time became the reference for everything east and west of it. In the twentieth century atomic clocks replaced the rotating Earth as the standard, and Coordinated Universal Time — UTC — took over as the basis of civil time; the story of that handover, and of leap seconds, is in UTC, GMT and leap seconds.

Why this matters for a countdown

Because time is standardised by zone, "midnight on 1 January" is a different instant in each zone, all defined relative to UTC. The board uses exactly those definitions, so the year ends first in Kiritimati and last on Baker Island, 26 hours apart, and it can show each one.

Sources

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