Meditações - ... And so the notion of “standard time” was born

Clock-regulated time began in 14th-century Europe, where every city and village had a sundial and measured the passing hours with ringing church bells. Still, these bells didn’t toll together; Venice and Paris, say, weren’t in sync.

Instead, every place, even those close together, operated on a slightly different time. Everyone agreed that noon was when the sun was highest in the sky. But the sun moves from east to west, so mid-day differed in various locales. The hour indicated on a sundial is called “apparent solar time,” or “true local time.”

It wasn’t until the 19th century that train travel exposed the need for a more uniform way of measuring time. “It is awkward to organize train timetables if each station marks time differently,” Rovelli writes. And so the notion of “standard time” was born.

Ephrat Livni em entrevista a Carlo Rovelli