From: ram@zedat.fu-berlin.de   
      
   Sylvia Else  writes:   
   >So now you have to synchronise spatially separated clocks, and to do   
   >that you have to must assumptions about space time. The obvious   
   >assumption is that special relativity is correct, and that you can use a   
   >method that synchronises clocks in special relativity.   
      
     One does not need to assume that special relativity is   
     correct in order to synchronize spatially separated clocks.   
     One can define that rulers retain their length when moved   
     around from one rest position to another rest position and   
     that light travels with the same speed into all directions.   
      
     Then, one can build a linear sequence of devices with equal   
     distances from each other (using the ruler) and synchronize   
     the clocks contained within many pairs of two such devices   
     with a light flash (emitted by the device which is in the   
     middle between the two). Then, when something comes flying   
     along that linear sequence of devices, its length can be   
     measured with a precision depending on the density of the   
     devices along that linear sequence. For this purpose, all   
     the devices might have an inbuilt photocell/camera.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)