Rob Seaman wrote:
... 3) Clarify the relationship between the civil second and the SI second. It may be too late to define a new unit of duration - whether Essen or Fressen - or perhaps it isn't. In any event, there are 86400 seconds per solar day, and that usage of the word "second" clearly differs from the SI unit which happens to have the same name. What are we going to do about it? (Certainly the ITU proposal does not address such issues.) ...
Perhaps it would be a mistake for the relationship between civil and SI seconds to be anything other than identity. There isn't a clear separation between the use of one and the other. Consider, for example, a TV system. The frame rate and so on of the TV signal would, presumably, be defined in SI seconds. On the other hand, the schedule for the day would be in civil seconds. Of course, the schedule doesn't need to be held to the exact second (though it's often done pretty close to that) but somewhere in the chain there would have to be a switch over. Where, exactly? In other words, I'm suggesting that any attempt to "fix" leaps (seconds, minutes, hours or whatever) by use of rate changes in civil time (relative to atomic time) results in a cure which is worse than the disease. Whether or not there are 86400 seconds per solar day is something which should be up for discussion - not taken as a matter of definition. Clearly, there's a use for a "solar second" but perhaps it's even more specialised than a sidereal second. Ed Davies.
