From: tjroberts137@sbcglobal.net   
      
   On 10/20/18 5:38 AM, Nicolaas Vroom wrote:   
   > The clocks used in the book SpaceTime Physics are not pointlike   
   > and the reason that tick is also because they are not pointlike.   
   > The reason that they behave differently is because the mirrors   
   > can be parallel or pendicular to the direction of motion.   
      
   I'll bet that in the book they are all moving inertially. Because if a   
   light clock with parallel mirrors is accelerated along a direction not   
   parallel to its light path, it will cease to operate, because the   
   mirrors will be accelerated away from the bouncing light ray.   
      
   	(That does not happen for any inertial motion.)   
      
   > My simulation assumes the same.   
      
   Then it cannot accurately model acceleration of a light clock (except   
   along the direction of its internal bouncing light ray).   
      
   > How can I understand a thought experiment when in reality a clock   
   > has 3 dimensions and in the thought experiment not. (only 1)   
      
   You need to learn about approximations, and how to determine when they   
   are appropriate (or inappropriate) to a given physical situation.   
      
   	BTW that is an essential aspect of an education in physics.   
   	Except for certain gedankens, physicists are always making   
   	approximations....   
      
   This seems to me to be the root cause of your confusions.   
      
   > My simulations of the movement of the planet mercury (using Newton's   
   > law) assume the same time at each iteration for all the planets   
   > considered. The position of the clock, in theory, is considered fixed.   
      
   I suspect you used a coordinate system, not a clock.   
      
   > What I want to know is why my simulations of clock in a linear   
   > accelerator or centrifuge are wrong.   
      
   That depends on myriad details....   
      
   > A more basic question is: why do we consider for example the surface   
   > of the earth at rest.   
      
   This depends on whether such an APPROXIMATION is appropriate to the   
   problem at hand. For playing sports it is both appropriate and very   
   accurate. For mapping stars and planets it is inappropriate and   
   hopelessly inaccurate.   
      
   Tom Roberts   
      
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