[LEAPSECS] LEAPSECS Digest, Vol 51, Issue 23

[Gerard Ashton]

On 2/8/2011 6:42 AM, Tony Finch wrote:

> On Mon, 7 Feb 2011, Rob Seaman wrote:

>> Tony Finch wrote:

>>

>>> the whole point of universal time is that it's the default timscale

>>> for civil use and only specialists should need anything else.

>> Stephen should add this to the consensus building list.

> Does that mean that you agree that its very tight coupling to earth

> rotation is a historical artefact rather than a necessary feature?

>

> i.e. "whole point" or "main point"?

>

> Tony (being argumentative).

 From a historical point of view, the whole point of universal time was 
to serve as a basis
of standard time zones, which in turn facilitated commerce (especially 
the forms of
commerce involving railroads, which crossed time zones fairly often, and 
crossed informal
local time domains very frequently). Interestingly, universal time was 
adopted about the
same time electromagnetic dissemination of time scales became possible.

So universal time was adopted because people in industrialized nations 
didn't want to
reset their watches too often as they traveled, and when they did, they 
wanted it to be
easy; change it by a whole hour. Furthermore they wanted the ease of 
receiving the
correct time by telegraph rather than having to set up some local 
structure to measure
solar time.

A secular change to civil time that would be perceptible without the aid 
of a clock has
never been introduced, so whether tight long-term coupling between earth 
rotation
is a historical artifact or necessary feature has never been tested.

Gerry Ashton