[LEAPSECS] LEAPSECS Digest, Vol 45, Issue 1

[Tony Finch]

On Fri, 3 Sep 2010, Zefram wrote:


> Tony Finch wrote:

> >                        As we have seen there are a lot of intricate

> >details whose necessity people can legitimately disagree about and no way

> >to determine an official consensus. Which is why I say that astronomical

> >GMT doesn't exist.

>

> Interesting argument.  I disagree with your central point: I don't

> think an official realisation of GMT is required in order for GMT to

> meaningfully exist.


Note that in the above I'm talking about astronomical GMT. There is an
official realisation of legal GMT, and it is UTC. If you create a new
astronomical timescale it would be wrong to claim it is GMT. GMT(Zefram)
is probably OK though :-)


> Making a clear distinction between ideal and realisation smells like

> modern behaviour; considering the many different meanings of "GMT" that

> have already been identified, I would not be surprised at it being

> irretrievably ambiguous in this respect.


Yes, definitely. I'm stretching when I claim that the practical realities
of time in the UK are enough to unambiguously define GMT == UTC
(obviously, or we wouldn't be having this discussion).


> Does anyone have relevant historical documentation on the philosophical

> definition of GMT?


This is brief and sketchy:
http://www.nmm.ac.uk/explore/astronomy-and-time/astronomy-facts/history/the-longitude-of-greenwich

Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7,
DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR
ROUGH. RAIN THEN FAIR. GOOD.