From: heathjohn2@gmail.com   
      
   On Tuesday, August 15, 2017 at 2:08:47 PM UTC-4, Tom Roberts wrote:   
   > On 8/9/17 12:55 AM, John Heath wrote:   
   > > The SR effects - GR say the traveling west bound twin's clock was   
   > > running faster not slower.   
   >   
   > Actually neither clock runs faster, and neither clock runs slower   
   > -- ALL clocks run at their usual rate, regardless of how they might   
   > move or where they might be located. But when measured in an inertial   
   > frame relative to which a clock is moving, it is OBSERVED to run   
   > slower than identical clocks at rest in the inertial frame.   
   >   
   > IOW: "time dilation" does NOT affect the clock itself, it is a   
   > geometrical projection of the interval between a moving clock's   
   > ticks onto the inertial frame used for the measurement.   
   >   
   > > It would make sense if there was a preferred FoR.   
   >   
   > There is no "preferred frame" in the usual sense of it being somehow   
   > "special" in the dynamics. But HUMANS who make calculations definitely   
   > prefer to use an inertial frame, as calculations are simpler in   
   > such coordinates than in non-inertial coordinates. Such human   
   > preference, of course, is irrelevant to nature.   
   >   
   > Tom Roberts   
      
   time dilation" does NOT affect the clock itself, it is a   
   > geometrical projection of the interval between a moving clock's   
   > ticks onto the inertial frame used for the measurement.   
      
      
      
   I have 2 clocks . One clock is a wind up clock with a spring and   
   the inertia of a wheel to keep time. The other is a pendulum clock   
   that uses the same inertia but no spring. The pendulum clock relies   
   on the gradient of gravity as a spring. We will move both clocks   
   from the 1th floor to the 30th floor. The wind up clock is fine on   
   the 30th floor other than running a hint faster but it is such a   
   small amount that it will not require re calibration. On the other   
   hand the pendulum clock "no spring , needs gradient of gravity "   
   is running much slower on the 30 floor and will require re calibration.   
   Pendulum clocks have adjustments built into them to compensate for   
   sea level to higher elevations to compensate for a change in the   
   gradient of gravity.   
      
   A] The pendulum clock runs much slower as the gradient of gravity   
   on the 30th floor changed.   
      
   B] A wind up clock runs a hint faster as the relative inertia of   
   mass in general on the 30 floor is a hint lower therefore the clock   
   runs a hint fast.   
      
      
   I think we can agree on the pendulum clock but when it comes to the   
   wind up clock you seem to be ignoring the root cause , change in   
   inertia.   
      
   Why would a pendulum clock have simple Newtonian reason for running   
   slow but the wind up clock is raised to a level of being above a   
   simple Newtonian reasoning of a change in inertia of the clock   
   itself. I guess what I am saying is the wind up clock is ticking   
   faster on the 30th floor for the simple reason of having less   
   inertia. Yes if one goes to the 30th floor the clock is not ticking   
   faster but that is only because the observer is now has less inertia.   
   In the big picture the wind up clock is ticking faster as it has   
   less inertia yes / on ? I do not see a need to complicate beyond a   
   simple change in it's relative inertia. I have drifted away from   
   SR into GR as SR has too many variables mixed together to make this   
   same argument.   
      
   [[Mod. note --   
   1. The term "the gradient of gravity" is a technical term in   
      Newtonian mechanics which doesn't have the meaning you want here.   
      The phrase you want is "the local gravitational acceleration,   
      often called 'little g'".   
   2. A spring clock's running rate should be independent of the   
      local gravitational acceleration, i.e., it should run at the   
      same rate on the 30th floor as at ground level.   
   	[One might ask "the same rate relative to what?"   
   	The answer is, relative to an ensemble of other   
   	high-quality clocks (all of them local, i.e.,   
   	self-contained and not based on observing the   
   	outside world) which use a variety of different   
   	timekeeping mechanisms.]   
   3. You're mistaken about inertia: we have strong experimental   
      evidence that a given mass's inertia does NOT depend on the   
      local gravitational acceleration.   
   4. A pendulum clock does indeed have a simple Newtonian reason   
      for running at a rate which depends on the local gravitational   
      acceleration g, namely, that it's an oscillator whose restoring   
      force depends on (and is in fact directly proportional to) the   
      local gravitational acceleration.   
   -- jt]]   
      
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