Lots more to this bizarre question inside.
I'm sure most people don't question that AD 1 was approximately 2003 years ago, but I can't find any evidence to make me believe in this 100% (sorry, comes with my faith, never believe blindly!)
Nowadays we have newspapers, TV guides, and scientific organisations like the NIST
who keep track of time for us. The first newspaper of modern times is said to have been started in the early 1600's (in Europe), and I am sure there were no long-running dailies through the Dark Ages. I'm also going to assume there were no people who ticked days off on a piece of wood, which they then handed down to their sons, and so on and so forth. So how do can we accurately know (to the number of days) how much time passed between AD 1 and now?
Two different calendar systems were in common use in the last two thousand years, the Julian
and the Gregorian.
Leap years for the early AD years are supposedly unknown, and were mostly illogical.
One solution I thought of was that items from Roman times (perhaps coins with dates on) have been carbon dated, which will tell us how many years ago the item was made, and at least prove that AD 1 wasn't really 3,000
years ago. But this still doesn't narrow anything down to the day.. and considering some countries actually leapt over several days in the transition to the Gregorian calendar, is there actually any definitive answer for this?