Sometimes we talk about how society is “path dependent”: what things
would be different if history had not followed its particular path?
One place that’s fun to think about is time. Until the
development of railways,
places used local solar time. Washington DC is at 77°W while NYC
is at 74°, so clocks in NYC would be set ~12min ahead of those in
DC.

Initially, this didn’t matter: traveling from NYC to DC was a multi
day endeavor, so a 12 minute difference in clocks was trivial. As
roads got better and then railroads were built, however, travel times
decreased enormously:

Atlas of the Historical Geography of the United States, 1932

If you’re running a railway system, it’s really very useful to choose
a single location’s time to use internally. Your workers are moving
East and West, fast enough for this sort of discrepancy to become a
problem, and they certainly don’t want to be continuously changing
their watches as they move from town to town. Railway schedules are
much easier to work with if they use railway time, people start using
railway time in their regular life, the government adopts a system of
time zones.

Imagine, however, that things had gone differently and we were still
on local solar time. At this point it would not be hard to make our
phones always report the correct time as we move east and west, since
our phones know where we are. Automated calendar software could deal
with local solar time with about as much effort as it could with time
zones. Do all routes to the present pass through a system of time
zones, or is there an alternative history where we really could be on
local solar time today?

Railroads need shared time much more than other forms of
transportation. There are a small number of high-capacity tracks, and
the same with vehicles. Efficient use requires central organization,
coordinated operation, and shared scheduling, which is far easier with
a shared time system. If instead of railroads we had developed cars,
it would still be annoying to need to reset your watch as you move
between places, but it would be much less of an issue. Perhaps we
could have had political systems which made private railways
impractical, combined with governments that were not competent enough
to run their own? Or progress in making lighter engines could have
been much faster?

Alternatively, if you had lots of North-South rivers or a society
distributed among islands in an archipelago, railroads would not be
practical and boats are much slower. Perhaps you could have the the
development of computers before the speedy East-West travel that
pushes for time zones?

The telegraph is also an interesting case, since it allows rapid
communication over long distances, if not travel. I don’t think the
telegraph or even the telephone provide enough impetus to move society
to switch to time zones. It’s just not much of a problem if the
telegraph operator in NYC thinks it’s noon when the operator in DC
thinks it’s still 11:48. You could have big tables showing the offset
of every city, and allowing quick time calculations when necessary.

With radio and television people do care
about what time different things are going to be broadcast. On the
other hand, they are naturally
geographically limited
:

Visualizing
the Geography of FM Radio, Erin Davis

This is probably enough to expand local time from being immediately
local to being maybe a ~40mi radius, but that is only about a 2min
time difference. On the other hand, an overlapping chain of broadcast
areas would have pressure to all use the same scheduling time, and at
least in continuously built-up areas like the Northeast United States
that would probably be enough to pull everyone onto the same time.

While the time zone system gives awkward discontinuities, where time
can jump a whole hour in a single step, at this point I would not
seriously push for us to move to local solar time. Still, it’s fun to
imagine histories that would have left us with that system.

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4 تعليقات

  1. I have been using my watch's solar dial theme for a while for non-work times and days. It's very interesting to see how solar time drifts — and a bit depressing at this part of the year how little daylight we get!

  2. I've contemplated a timeless world a few times.

    What would things be like if there were no synchronization or concept of hours, minutes, seconds at all?

    There would still be loose concepts of time because of the position of the sun, but without precise time things might be less rushed.

    In space we'll have to deal with a truly perpetual existence. I wonder what we'll be doing for scheduling 50,000 years from now.

  3. I guess this is relevant today as many (?) countries switched from dst back to normal time. As someone who happens to live at a location where normal time aligns pretty well with solar time, that makes dst feel extra bit silly. For reference, today solar noon happens at 12:04 local time. During spring the difference is greater, e.g. in late March (before switch to dst) solar noon will be at 12:25 local time. But the final irony is that dst shifts the time in wrong direction, pushing the solar noon to 13:xx during summer!

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