pytz has so many timezones!

[Bill Hamilton]

On 10/9/07, mensanator at aol.com <mensanator at aol.com> wrote:
> On Oct 9, 8:34 am, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> > mensana... at aol.com wrote:
> > > On Oct 8, 1:03 pm, Carsten Haese <cars... at uniqsys.com> wrote:
> > >> On Mon, 2007-10-08 at 10:41 -0700, mensana... at aol.com wrote:
> > >> > For example, Windows has seperate listings for
> >
> > >> > Central America
> > >> > Central Time (US & Canada)
> > >> > Guadalahara, Mexico City, Monterry - New
> > >> > Guadalahara, Mexico City, Monterry - Old
> > >> > Saskatchewan
> >
> > >> > but they are all GMT-6
> >
> > >> But they could have different rules for Daylight Saving Time.
> >
> > > Which only matters if you're setting your clock.
> >
> > That's BS. If I'm supposed to be attending a video-conference that spans a
> > few continents which is scheduled using a web-app, it's VITAL that I get
> > the invitation and reminder rendered in MY local timezone, DST included.
> >
> > And for the matter of
> >
> > """
> > There are only 25 timezones: -12, -11, ... -1, 0 (GMT), +1, ... +11,
> > +12.
> > """
> >
> > who says that timezones have to be separated by one hour each?
>
> The Earth says. It takes 24 hours to revolve.
It only takes 24 hours for the Earth to revolve once because we
defined an hour as 1/24 of the time it takes for the Earth to revolve
once.  We could have said an hour was 1/10 that time, or 1/2, or
1/27.284.

>
> > Or why don't we have a global time?
>
> Like UTC?

What about GMT?  I hear that much more than UTC.

>
> >
> > Your 25 timezones are an abstraction the same way
>
> Not the same way at all. The 25 timezones I speak of are
> not merely an abstraction, but related to longitude.
>
> > as are the 400 apparently in use by people all over the world
>
> Where the correlation to longitude is much looser.
> Granted, it doesn't need to be for non-navigational
> purposes. And although governments can legislate things
> like DST, they can't legislate longitude.
>

But your 25 timezones are only useful to the people that use those 25
timezones.  And the time zone I use is not one of those 25 timezones.

> > - and last time I checked, there was no
> > fundamental law in physics or such that limited the allowed or sensible
> > number of timezones...
>
> Isn't there some law somewhere that says the circumference
> of a sphere is 360deg? Doesn't that same law mean that no two
> points on a sphere can be seperated by more than 180deg
> longitude? Doesn't that make GMT+13 non-sensible?

A timezone is an arbitrary geographical designation.  It has nothing
to do with latitude or longitude.  While some time zones may be
defined as a geographical region between two longitudes, others may be
defined by geographical borders or convienent terrain features.  Take
a look at the international date line.  It doesn't follow a
longitudinal line, but instead jogs east around Asia and then west
around the Aleutian Islands.


--
-Bill Hamilton