Anyway...
Just as we have a Kelvin scale for temperatures, I think we could have something similar for dates... So far we only have been able to date the Big Bang with a margin of error of fifty million years but it's not impossible that in a near future we could be able to pinpoint it more precisely, perhaps with great precision even. We could then have a calendar with only positive dates, just as there aren't negative Kelvin temperatures. Of course, it wouldn't be very practical as the current year would be something like 13,789,145,929!!
That would definitely take some getting used to.
would you want to define the moment of the big bang (thursday morning 7 minutes into the kojak rerun on tv5) as january 1st or would you come up with sth totally new?