[LEAPSECS] Leap smear

[Clive D.W. Feather]

Rob Seaman said:

> The concept of operations for civil timekeeping is time-of-day.  And

> time-of-day *means* mean solar time.


Rob, you've been harping on about this for years. Last time, it was:

>>> - the civil day is the synodic day



> Just as the rate of TAI is the SI-second, the rate of universal time is

> the synodic day.  Civil timekeeping - time kept for a multitude of purposes

> for our society's cultural and technical purposes - is obviously connected

> to the the day-and-night cadence of our calendar.


This is the single biggest objection I have to your position, and I suspect
others agree with me. You are (or appear to be) trying to sneak in the
definition that the civil day is the synodic day, and then use that to
"prove" that your approach is correct.

THAT IS NOT HOW IT WORKS IN THE REAL WORLD.

If you ask the man on the Clapham omnibus [1], he will probably say that a
day is *roughly* related to the rising and setting of the sun. He won't
understand about synodic days. He knows that the times of sunrise and
sunset vary a lot. He probably thinks that the sun reaches the highest
point in the sky at 12:00 every day (13:00 in the summer; he'll know about
British Summer Time and may well curse the requirement to go around the
house and change all the clocks). In other words, he thinks that time is
apparent solar time. Indeed, since the legal requirement to use car
headlights is based on sunrise and sunset, he'll be pretty sure he's right.
He certainly has no idea what the "Mean" in "Greenwich Mean Time" actually
means.

On the other hand, he probably defines "the time" as "whatever the BBC
announces" or "what Big Ben [2] says", or by the Greenwich pips [3].

But the man on the Clapham omnibus doesn't get to define the civil day, and
nor do you.

The people who get to define "civil day" are (strange, this!) the civil
authorities.

The problem we, as relative experts, have is that the civil authorities for
the most part haven't bothered to think about this. Some, such as the UK,
are working on tradition (no politician wants to be seen as "abolishing
Greenwich Mean Time"). Others have heard that atomic clocks are wonderful
and precise, and that "UTC is designed for civil timekeeping", so they've
decided to use UTC. All of them are happy to play around with local time if
they see some benefit (e.g. the British Standard Time experiment).

What has never been done, as far as I know, is for someone to actually ask
the civil authorities whether they would prefer a synodic or atomic day [4].
It may well be that people actually want predictability more than they want
their sundials to be correct. And it may well be that, in however many
hundreds of years (I forget) it will be before we reach a (say) 3 hour
difference, enough people will be working shifts or partying all day/night
that nobody cares about the sun any more.

But what you can't do is try to cheat by defining the terms to support your
side of the argument.

[1] ObTWIAVBP: the average person; he has a reasonable knowledge but has
not studied and is not an expert in whatever field is being discussed.

[2] Big Ben is actually the bell in the Clock Tower of the Houses of
Parliament. The clock is just "the clock".

[3] A sequence of 5 short and one long beep originally provided by the RGO
and transmitted by the BBC at the top of some hours.

[4] Hmm, thinking about it, the Coordinated Universal Time Bill might be a
counter-example, but it wasn't handled in the best way if so.

-- 
Clive D.W. Feather          | If you lie to the compiler,
Email: clive at davros.org     | it will get its revenge.
Web: http://www.davros.org  |   - Henry Spencer
Mobile: +44 7973 377646