There’s an extra second tacked on to the end of 2016 because after millenia of calendar-making and time-keeping we still have to make adjustments and anyway we’re using a solar calendar that’s adapted from a lunar calendar originally created by the Romans which they discovered was unreliable, for long-term record-keeping anyway, since the winter months would gradually shift into summer and vice versa.
The whole idea of calendars is pretty arbitrary anyway, our small attempt to bring some regulatory order to a universe which isn’t interested in our timetables. As a kid I thought it was strange that the new year fell right in the middle of winter when it seemed like it would make more sense to have it occur at a change of seasons, and a lot of other cultures thought the same thing. It seemed like a contradiction to start over right in the middle, but contradictions, like calendars, are completely artificial constructions that the universe isn’t interested in. We think of hot and cold or dark and light as opposites, but they’re really simply different coexisting and overlapping states, and when you get right down to it even anti-matter can be created from matter; it exists within matter. Some scientists think the pre-Big Bang universe contained 51% normal matter and 49% anti-matter and it was a collision of the two that started everything and spread everything that we are and can see all across space. If that’s true then it’s pretty amazing to think that not only are all the stars and planets merely 1% of all matter that once existed but that the proto-universe was so full that you never had to worry about the buffet running out of crab legs, but that’s another story.
I know this is all crowded with a lot of strange and seemingly unconnected ideas but the point is whether it’s arbitrary or not enough of us recognize the end of one year and the start of a new one that it influences our consciousness and is seen as both an end and a beginning, opposites colliding.