Forum: Author Hangout

a link to the last time you asked this question.

Hmm, looking back at the many, many questions PotomacBob asked, I suspect an ulterior motive: He tries to get the authors here to spend too much time in answering and reading all the other answers, so they slow down significantly in writing their own stories.

Maybe instead he is a clinical case of galloping dementia.

HM.

Consider the Gregorian calendar, which starts at 1 A.D. Centuries later, we're still arguing about when the new decade, century, or milennium begins.

That must be so because A.D. is the abbreviation of anno Domini, meaning the 'year of the Lord'. Therefore the year of Jesus birth is the first year of the Lord.

The biggest problem with anno Domini is that Dionysius Exiguus, an eastern Roman monk, created this term in AD 525 counting back in at least two older calendar eras:
The Era of the Martyrs (Latin: anno martyrum), also known as the Diocletian era (Latin: anno Diocletiani) was used by the Church of Alexandria until then, but Diocletian began his reign on 20 November 284 AD.
The Diocletian era was not used bei western Christians who continued to designate their years by naming the two consuls who held office that year. Trying to count back in this system for hundreds of years was error prone, so it's quite certain Jesus' birth year was not AD 1.

Back then the had no concept of 0 (zero), the year before Jesus' birth should be year 0 but is 1 BC.
To make it even more complicated, astronomical year numbering avoid words or abbreviations related to Christianity, but use the same numbers for AD years (but not for BC years; e.g., 1 BC is year 0, 45 BC is year −44).

AFAIK, the NASA counting system does not use the 0, T is defined as the event with no duration at all. Therefore the time difference between T-1 and T+1 is only 2 units if they used the 0 it would be 3 units. BTW, the same logic is used for years in our calendar, just the starting point (event) is offset to the beginning of the year.

HM.

What happened in Canada or the United States on September 10, 1752. NOTHING!!! That date does not officially exist!

For the historian things can get real messy depending on the year. Most of the world uses the Gregorian calendar now (with every 4th year being a 'leap' year [365-366 days]. Prior to that the Julian calendar was used (365 days). The change over happened at different years in various countries. The reason for the change was the date was starting to not match the season. When the change happened in Canada and the United States on September 2, 1752; the NEXT day was September 14, 1752 (11 days). However, because Alaska at this time was owned by Russia, the conversion didn't happen until October 6, 1865.

I have been doing research on the Russian American Company in Alaska. In most of the books that I have used, when the author quotes a date from something written in the 1600's and 1700's by Russians it is usually given 2 dates (OS and NS). Russia did not convert until 1918 (13 days).

Most of the world uses the Gregorian calendar now (with every 4th year being a 'leap' year [365-366 days]

Not quite.

By that, every century year would be a leap year, but that is not the case. Century years 1800, 1900, 2000 are only leap years if they are evenly divisible by 400.

So 1600 and 2000 were leap years, but 1700, 1800, and 1900 were not.

What happened in Canada or the United States on September 10, 1752. NOTHING!!! That date does not officially exist!

Nothing happened in the United States on September 2, 1752 or September 14, 1752 either. Why? Because the United States didn't exist until the Articles of Confederation was adopted on November 15, 1777.

Most of the world uses the Gregorian calendar now (with every 4th year being a 'leap' year [365-366 days]. Prior to that the Julian calendar was used (365 days).

Not quite right, the Julian calenda already had leap years (every 4th year without exception) it was decreed by emperor Julius Cesar with the intention to stop the running off between date and season in the old Roman calendar. However the Roman priests inserted more leap days. Augustus corrected this by decreeing 12 years without leap days.
(over the centuries, while agreeing about the general facts, scholars came up with different details which years were made leap years by the priests and when the 12-no-leap-years period of Augustus actually startet).

Because the Julian calendar wasn't exact enough, they had to cut off thee leap days within 400 years. This was done in the Gregorian reform. Giving us this rule.
Evenly divisible by four: leap year; evenly divisible by 100: no leap year; evenly divisible by 400: leap year.
Using this rule 1600 is a leap year, 1700, 1800 and 1900 are no leap years, 2000 is a leap year.

Microsoft's programmers ignored the third part of the rule letting Windows in 2000 ignore February, 29th and jumping from February, 28th to March, 1st instead.

This Gregorian reform is still not 100% exact, but the rule will not be changed further. To correct the minor differences leap seconds are inserted (or omitted) at midnight between end of the old year and start of the new year.

HM.

This Gregorian reform is still not 100% exact, but the rule will not be changed further. To correct the minor differences leap seconds are inserted (or omitted) at midnight between end of the old year and start of the new year.

Further modifications wouldn't be practical. There are 86,400 seconds in a day.

It would take a very long time for the Gregorian calendar to be off by a whole day.

With modern time keeping devices accurate to milliseconds being available, doing the ad-hoc leap seconds makes more sense.

To correct the minor differences leap seconds are inserted (or omitted) at midnight between end of the old year and start of the new year.

Not quite...
Leap seconds were inserted as you say, or at the end of June (and we never needed a second removed, but they would have been removed at the same times). BUT, leap seconds may be officially abandoned for a while, so the time will now be allowed to drift relative to the year.

My favourite calendar quirk, though, is February 30th

You all are correct in the details. I was just painting with a broad brush.

An interesting and related question is how old is someone born on February 29th, since they only have a birthday once every 4 years. :)

A critical plot element of G&S's Pirates of Penzance!

A critical plot element of G&S's Pirates of Penzance!

Truly, you must be as learned as a Major General.

Truly, you must be as learned as a Major General.

That's a "Modern Major General". Back to class for you.

An interesting and related question is how old is someone born on February 29th, since they only have a birthday once every 4 years. :)

I always argue that the person ages as the earth still goes around the sun once every year but thanks to the calendar you only need to give them a gift/card once every 4 years.