[LEAPSECS] Lets get REAL about time.

[Warner Losh]

On Jan 24, 2012, at 4:01 PM, Mark Calabretta wrote:


> 

> On Tue 2012/01/24 07:18:36 -0800, Steve Allen wrote

> in a message to: Leap Second Discussion List <leapsecs at leapsecond.com>

> 

>> The ones with WWVB

>> receivers in them do a little dance every night when nobody is

>> watching and the signal is strong, and that dance looks a lot

>> like the handling of a leap second.

> 

> There are two basic types of analogue clock display.  One where the

> second hand steps around the dial from second to second (thus

> disawowing sub-second timekeeping), and the other where it moves

> smoothly and continuously.  It is interesting to contemplate how a

> leap second would appear on each were it to be implemented.

> 

> In the former, on reaching 60, the second hand would stay there for 2

> seconds thus making it impossible to track time during a leap second.


Or it could "stutter" to the next second so you'd at least know a second was ticking..


> In the latter, the second hand would move continuously past 60 to 01

> second and immediately flick back to 60, thus making it possible to

> reckon time during a leap second.


Or it could move from 00 back to 59...

And the number of choices here is illustrative of the implementation details elsewhere :)

Warner