Wednesday, 22 May, 2002

Does Anybody Really Know What Day It Is?

I've been wondering recently about time.  Not hours and minutes, or millennia, but rather simple calendar time.  Today is May 22, 2002, by the Gregorian Calendar that's been adopted by most of the world—at least for purposes of navigation and scientific reference.  There are countless other calendars, a brief study of which is very revealing.  A good place to start is  As good as the discussion is, though, it doesn't answer my question.

How do I know that today is May 22, 2002?  I think we have reasonably good records for any date after 1582 (when Pope Gregory changed the calendar), and perhaps for a century prior to that.  But prior to, say, the middle of the 15th century, written records are somewhat spotty.  With all of the calendar machinations between the Julian calendar's adoption in 46 B.C. and today, can anybody say with any certainly what today's date is?  Can we say with any authority exactly how many days have passed since that date?  I somehow doubt it.  I think we'd be hard pressed to say, with an accuracy of plus or minus 10 years, how many actual years have passed since the Julian calendar was adopted.  The AD/BC system wasn't adopted until 500 or so A.D., and at that time there was some question as to the exact year of Jesus's birth.

I'd like to know how far back we can reliably count days.  The only way I can think of is to find dated documents that were written on each and every day, going back as far as we can.  And the dates on those documents would have to be corroborated by references from other documents, verifiable content (i.e. today was the great fire), or perhaps the reputation of the document's author.  I would think we could get back 100 years in a single newspaper's archives.  Could we go 200 years?  Could we get back to 1582?  How far back would we have to go before we couldn't say for sure what day it was?  Why this is important, beyond rubbing a rad fundie's nose in it from time to time, I can't really say.  But it sure would be an interesting archaeological exercise.