The story goes that it began with a missed train. In 1876 a Canadian railway engineer named Sandford Fleming, so the telling has it, arrived at a station to find he had misread an ambiguous timetable and watched his connection leave without him, and out of that small humiliation grew a large idea: the world needed not just shared time zones but a single, agreed starting point from which all of them could be measured.

Zones alone were not enough. Each was defined as an offset, so many hours ahead of or behind some reference, and an offset means nothing without a reference to count from. The globe needed a line marked zero, a prime meridian that everyone would accept, and there was no natural one; any meridian could serve, so the choice had to be made by agreement rather than discovered by measurement. In 1884 delegates gathered in Washington for the International Meridian Conference to settle it, and after the arguments they chose the line running through the Greenwich observatory in London as the world's zero.

With that single decision the world's clocks gained a common origin, and every zone could finally be named as a clean distance from it. The choice still governs how we write time today. The Z that marks a coordinated universal time is Greenwich's direct descendant, standing where that zero line was drawn, and the offsets we append to local times, the plus and minus hours and minutes, are simply the zones the railways carved measured back to Greenwich. A conference in 1884 reached down through more than a century to shape the timestamps in a modern log file. The missed train, if it really happened, was well avenged.