A thread on another board had a topic regarding military time, and it got me wondering - who invented this am/pm garbage and why do we have it?
Well, the 12-hour clock was invented by the Sumerians, so it has a bit of history behind it.
The actual terms of a.m. (ante meridian) and p.m. (post meridian) are related to the system of dividing up the planet into 24 time zones, called Universal Time. This was the idea of Sandford Fleming, a Canadian engineer who was upset at missing a train.
Though to be correct about it, a.m. and p.m. are actually abbreviations for the latin ante meridiem and post meridiem.
It depends on what you mean. Recognizing that the sun is before or after its zenith is, no doubt, something that people have been doing as long as there have been people. The modern names for the concept come from Latin.
Good good, but why do we use the 12 hour clock?
Why doesn’t the entire world run on the 24 hour one?
It’s difficult to divide a cirlce into 24 pieces and make it easily readable. Much easier with 12.
Digital clocks solve this problem, but are a fairly recent invention, so the tradition carries on.
Also, when the measurement of time was being developed, no one needed to know the time after sunset.
James Burke claimed on “Connections” that the twelve hour clock came about because when spring wound clocks were invented, nobody could make a spring that would operate a clock movement for a full day, and 12 hours represented one wind-up. Take it or leave it.
Sorry, but it looks like ol’ Jimmy fell for an urban legend. The 12-hour system goes back to the ancient Sumerians (like JeffB says) so it predates spring-wound clocks by thousands of years.
In a word: inertia.