Losing Track of Time

 

We like our categories definitive and our time uninterrupted.  Nature, however, doesn’t care about what we like to project onto it. Time is especially tricky.

I’ve written before about the relatively recent division of time we call minutes and seconds.  But once we wanted to use these arbitrary, definitive categories for time, it turned out our leap year system was no longer good enough to keep us perfectly lined up with the OG timekeeping device: Astronomical events (solstices and equinoxes signaling the start of seasons).  

(Side note:  you probably don’t actually know the rule for leap years (because it is not, of course, exactly 365.25 days in a year); the rule is: extra leap day occurs in each year that is a multiple of 4, except for years evenly divisible by 100 but not by 400.)

Since the invention of atomic clocks in the late 60’s, we have actually been keeping ‘universal’ (a misnomer if ever there was one!) time down to the second.  However, to keep things lined up to the second, we had to introduce the leap second.  Unbeknownst to most folks, we have actually quietly slipped in an extra second 27 times at midnight, either at the end of June or the end of December. 

The problem is, just like when 1999 was turning into 2000 and all these computers that were only keeping track of the last two digits of the year were about to get messed up, many modern computers that are rectifying things down to the second are now getting messed up when the leap second happens.

The solution has just been decided on (Thanks to Isabelle for pointing this out to me!).  We will now do for the second what the leap year system does for the annual drift of a few hours:  we will wait until enough seconds have accumulated to do a big leap hour with plenty of warning.  At least a few 100 years will be needed before we have to worry about it…

The Leap Second

1972 - 2027