[LEAPSECS] Caveat emptor!

[Rob Seaman]

Tony Finch wrote:


> I see no big difference from the current ambiguity of the terms UT and GMT and UTC. You seem to be complaining that people who don't care about precision will use imprecise terms ambiguously.


Currently they are variations of the same concept.  Yes, there is a difference between imprecise (or rather, controlled precision) realizations of an unambiguous concept, and ambiguous realizations of multiple concepts.

Redefining UTC without leap seconds turns UTC into a static offset from TAI - hence the notion that TAI would subsequently be a candidate for suppression.  Unless you are arguing that TAI is a type of mean solar time, UTC will no longer be mean solar time - and also hence the kaleidoscopic dancing timezone scheme to recover mean solar time (to whatever controlled precision) for local use.

Which is to say that "Coordinated Universal Time" will no longer be "Universal Time" as it has previously been defined.  Thus confusion.

In the absence of coherent advance planning I suggest that Greenwich Mean Time will evolve back into revived usage.  We should get used to descriptive phrasing like:

	'...see table 7.  Column 3 is Coordinated Universal Time (UTC post its redefinition for convenience in 2018), whereas column 4 is "Universal Time", that is, the general equivalent to Greenwich Mean Time.  At the time of this writing the offset is 9 seconds.  Correct interpretation for subsequent rows contemporaneous with your reading will require that you read Appendix B (see also footnote 17).  The UTC column (actually an offset from the pre-2018 TAI (International Atomic Time)) and the GMT column (the *actual* Universal Time) are both necessary for evaluating formula 28 on page 692.  Use care in keeping them straight and watch the minus sign in the final term of the expression.  If you wish to apply this transformation to data sets pre-2018, simply use the old-style UTC everywhere."

Rob
--
"The poets made all the words, and therefore language is the archives of history, and, if we must say it, a sort of tomb of the muses For, though the origin of most of our words is forgotten, each word was at a stroke of genius, and obtained currency, because for the moment it symbolizes the world to the first speaker and to the hearer. The etymologist finds the deadest word to have been once a brilliant picture. Language is fossil poetry. As the limestone of the continent consists of infinite masses of the shells of animalcules, so language is made up of images, or tropes, which now, in their secondary use, have long ceased to remind us of their poetic origin."
- Ralph Waldo Emerson