From: ttt_heg@web.de   
      
   Am Mittwoch000015, 15.10.2025 um 20:05 schrieb Paul B. Andersen:   
   > Den 15.10.2025 09:44, skrev Thomas Heger:   
   >> Am Montag000013, 13.10.2025 um 21:59 schrieb Paul B. Andersen:   
   >   
   >>>   
   >>> What the display on a 'clock' shows is a 'point in time'.   
   >>>   
   >>> I can say that the 'time' now is October 13, 2025, 14:34:32 CET   
   >>> That's 'a point in time'.   
   >>>   
   >>> If I left my home at   t1 = October 13, 2025, 7:05:10 CET   
   >>> and arrived at work at t2 = October 13, 2025, 7:59:50 CET   
   >>> Then I can say that the 'time' I used to walk to work today   
   >>> was 54 minutes and 40 seconds.  (Δt = t2 - t1)   
   >>> That's a duration (or 'interval').   
   >>>   
   >>> So "time" can be both 'a point in time' and a duration.   
   >>   
   >> No: a point in time is also a duration, but where the reference point   
   >> (= the beginning of the interval) is assumed to be known already.   
   > You _know_ that we in the western world specifies "points in time"   
   > with the Gregorian calendar and the time zones based on UTC.   
      
   Sure, but we could actually use all the other Popes, too, and could use   
   their calendars, if we wished to do that.   
      
   So: UTC is just one selection from a plethora of possibilities.   
      
   >   
   >>>   
   >>> If we are only interested in durations, we may choose to   
   >>> use a clock we can set to zero at any time.   
   >   
   > We are free to choose our time scale any way we want.   
   > But it must be precisely defined, it is not 'given by nature'.   
   >   
   > Gregorian calendar and time zones based on UTC is   
   > what 'everybody' uses in their everyday life.   
      
   No, that is absolutely not true.   
      
   We have actually several time systems in use today.   
      
   Among the more important ones are the calendars of the Jews and the Muslims.   
      
      
   > You use your wristwatch to meet at work at the right   
   > 'point in time', don't you?   
      
   Well, sometimes.   
      
   Most of the time I use actually a different kind of clocks, which are   
   based upon a timing signal, which gets broadcasted by some agency in   
   Germany.>   
   > But for scientific work, we will probably use other definitions of   
   > our time.   
      
   Sure, but not because our needs are higher, but because time has nothing   
   to do with clocks.   
      
   ...   
      
      
   TH   
      
   --- SoupGate-Win32 v1.05   
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