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Re: [ontolog-forum] Looking for some pragmatic guidance on modeling rela

To: ontolog-forum@xxxxxxxxxxxxxxxx
From: John F Sowa <sowa@xxxxxxxxxxx>
Date: Wed, 08 Apr 2015 23:14:42 -0400
Message-id: <5525EEA2.8090407@xxxxxxxxxxx>
John B, Steve, and Robert,    (01)

> Maybe there is a need for a more cosmic time standard. We are a long
> way from that point, but there are issues associated with planetary
> exploration.    (02)

Atomic clocks on earth are probably more accurate than any we could
find or send outside of the earth.  A colony on Mars would certainly
use a Martian clock that could be synchronized periodically with the
earth clock.    (03)

> These kinds of issues are why I was hoping somebody had already modeled
> all this…    (04)

There are many aspects to these problems.  Have you contacted anyone
at NASA about what they do?    (05)

In any case, a general ontology for partially ordered clock systems
can be useful for many purposes:    (06)

  1. The problems with satellites and colonies outside earth.    (07)

  2. The typical problems of cheap clocks that are synchronized
     by error-prone methods at unknown intervals.    (08)

  3. Relating historical data from periods with poor clocks
     and unreliable records.    (09)

  4. Relating geological data when errors of thousands of years
     are common.  (And recognizing that the rotation of the
     earth may be slowing down at an unknown rate over long
     periods of time.)    (010)

  5. Planning for the future.  Some events are fairly predictable,
     such as the events printed on calendars for years in advance.
     But even those can be disrupted by unforeseeable disasters.    (011)

> If the goal is to model GR...    (012)

The issues about GR can be decoupled from the issues about time.
You just assume two kinds of "local" time:  time on earth with
clocks that are handled in the usual way, and time on the
satellite with its own local clock.    (013)

GR would be used to compute a function f(t) that would relate
the "clicks" on the satellite to the clicks on the earth.    (014)

John    (015)

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