[LEAPSECS] leap second roundup 2017

Rob Seaman seaman at lpl.arizona.edu
Wed Oct 25 09:14:56 EDT 2017


Newcomers to this list should realize that the same people have been
having the same discussion for 18+ years. All possible talking points
have been well-covered in the archives:

    Since 2007: https://pairlist6.pair.net/mailman/listinfo/leapsecs
    Before 2007: http://www.ucolick.org/~sla/navyls/
    Context: http://ucolick.org/~sla/leapsecs/

Some talking points remain unanswered:

If the ITU succeeds in their quixotic goal of redefining Coordinated
Universal Time to no longer serve as an approximation of Universal
Time...then what? That is, if UTC were to no longer approximate UT1,
what do we then call the concept of "Mean Solar Time at the Prime
Meridian"? Indeed, how do we describe the concept of a Prime Meridian in
that case? It will no longer be stationary with respect to civil time.

UTC would either no longer be able to claim to be UT, or UT will no
longer mean anything like what Universal Time has been since long before
the atomic clock era.

Of course, civilians will continue to confuse GMT with UTC, so Greenwich
Mean Time would have to go, too. "London Mean Time" will be unambiguous:
Mean Solar Time in London. But "Greenwich Mean Time" might represent a
similar concept, or might mean "Coordinated Universal Time".

UTC itself will always have the historical leap seconds embedded in it.
If anything, people on this list will find themselves discussing the
concept more often - or, at least, more extensively - than currently.
"But Daddy, why were the leap seconds there in the first place? Where
have they gone?"

UT1 is a specific realization of the general concept of UT. What do we
call that concept if Universal Time and UT have been hopelessly confused
by allowing UTC and UT1 to diverge?

Rob



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