Steve Allen wrote on 2005-01-24 06:09 UTC:
> But the current strategy of retaining the name UTC creates one real
> and unresolvable problem that will persist indefinitely. It is very
> bad policy to corrupt the historical meaning of anything called
> "Universal Time" by redefining UTC to be something that has no
> relation to the rotation of the earth.
It has been historically rather bad terminology to start with, so I
wouldn't shed too many tears here.
"Universal Time" sounds to me like a more suitable name for a time scale
that is linked to a property of the entire known universe, say a
frequency defined by the electron configuration of the caesium atom.
"Terrestrial Solar Time" would have sounded like a *far* more fitting
name of a time scale that is linked to Earth's rotational angle.
Unfortunately, astronomers chose their terms exactly the wrong way round
in a counter-intuitive way, where "Terrestrial Time" is actually a
physical time scale and "Universal Time" is an Earth angle time scale.
Of course, relativity tells us that there is no such thing as a
"Universal Time", and that we have to attach any time scale to some
coordinate system (e.g., barycenter of sun or earth).
It would be nice to have a more streamlined terminology, where
individual words/letters in the acronyms unambiguously indicate
- whether the time is physical (counting SI seconds) or solar
(defined by the position of the mean sun relative to a body
in the solar system)
- if it is physical time, where the relativistic reference frame
is attached (barycenter of the milkyway, sun, or some planet,
or the surface of some planet)
- if it is a solar time, which planet and how is the prime
meridian defined
- if it is a solar time, which periodic deviations have been removed
Markus
--
Markus Kuhn, Computer Lab, Univ of Cambridge, GB
http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__
Received on Mon Jan 24 2005 - 01:24:00 PST