Apropos very long running clocks: I wonder how long we've been counting the days of the week for without interruption? Ie was there ever some time of great upheaval when eg the Jewish people slipped up, and accidentally phase-shifted their sabbath?
I was originally going to write "Since Friday, 15 October 1582", since that was the first day of the Gregorian calendar.
But the previous day on the Julian calendar was Thursday, 4 October 1582. So even though there was a jump in the day number, the weekdays remained monotonic.
So maybe the correct answer is 1 January, 45 BC, the day the Julian calendar took effect, which was apparently a Friday.
For anyone interested in such oddities, here's an email from a DEC engineer in response to an alleged bug report back in the 90s that goes into a brief but very deep dive of the history of calendar, including the jewel about the jump between the Julian and Gregorian calendars (and the continuity of the days of the week):
More to the point, that email suggests that there's a good chance the continuity of the days of the week predates even the Gregorian calendar and goes back to the founding of the Roman empire, as presumably Mercedonius wouldn't have given anyone a reason to suddenly change the days of the week.
Does my unix date utility take into account these occasional leap seconds? And are these just hardcoded in the library itself and updated once in a while?
...which can be added to ntpd's configuration if you want your system's leap second to occur exactly on time.
Even if you don't, the leap second will eventually take effect via an update from your configured remote ntp servers, or your GPS source, or wherever you get your time from.
We might be able to discover if this had happened - for example if an eclipse occurred in historical documents on a certain Friday, but we would be able to calculate that it had actually taken place on Saturday, indicating that a day had been "lost" between then and now.
Interesting query. I wonder if anyone ever realized this had happened and came to the conclusion that the ceremony around it all, now that it's not on the "right" holy day, is completely man-made.
