GMT vs. MT
From The Boston Globe:
Last August, on the first day of Ramadan, the largest clock in the world began ticking for the first time. The Mecca Clock, designed to serve as the authoritative timepiece for the world’s 1.5 billion Muslims and positioned at the top of the world’s largest clock tower, poses not only an architectural challenge to England’s iconic Big Ben, but a political one as well. Defying the global agreement to consider Greenwich, England, the zero-point for measuring time and space — based on when the sun crosses over that meridian — the clock was constructed to run not on Greenwich Mean Time but on Mecca Time, with Mecca as prime meridian. This means that the Mecca Clock, and anyone who sets a watch by it, deviates from standard time by roughly 21 minutes.
To most of us, protesting Greenwich Mean Time (or its Greenwich-based modern successor, Universal Coordinated Time) may seem bizarre. Synchronizing every clock on earth to the minute offers innumerable advantages for global communication and travel, and most of us have become accustomed to the ease of moving our hour hands forward or backward based on time zones, which are in turn based on longitudinal distance from Greenwich. But in fact, consensus on world standard time isn’t much more than a century old — and was the subject of protest right from the beginning.
Many industrial powers began to struggle with the often awkward and impracticable distinction between their Greenwich-synchronized transportation networks and the civil time set by local or national observatories. Belgium, which had been willing to consider a narrow adoption of a Greenwich meridian but objected to its incursion into civil life, finally conceded in 1892. In Ireland, Dublin continued until World War I to observe two times: a Greenwich-based time for its seaport and a Dunsink-based time for all its city clocks, a situation that notoriously led James Joyce’s clock-watching character Leopold Bloom, in “Ulysses,” into confusion.