From: nicolaas.vroom@pandora.be   
      
   > On Sunday, 4 August 2019 12:18:00 UTC+2, Tom Roberts  wrote:   
   > > It is easy to set up a twin scenario in which two twins orbit a mass,   
   > > one in circular orbit and one in a highly elliptical orbit, such that   
   > > they meet periodically. Both have zero proper acceleration.   
   > > It can be arranged so either one has the larger elapsed proper time   
   > > between meetings.   
      
   This experiment is not very clear. That is why I have setup   
   a different experiment.   
      
   > The answer lies in the details of this (each) experiment.   
   > C2 orbits around the earth in one year (relative to C1).   
   > C3 orbits around the earth in 10 years (relative to C1)   
   > C3 will make 1 revolution around the earth. C2 10 revolutions.   
   > After 10 years (earth time) they will all meet again on earth.   
   > This is a general rule:   
   > 	The duration (earth time) for all observers is the same.   
   >   
   > [[Mod. note -- I don't know what you mean by that last sentence.   
      
   The whole idea is that the experiment for all observers takes   
   the same time i.e. 10 years (central mass or earth based) time.   
      
   > In Tom Roberts' scenario we are comparing /proper time/, i.e.,   
   > readings of clocks carried by the various observers.  That is,   
   > we first synchronize clocks #1, #2, and #3.   
      
   The clocks for all observers are all only reset at the start of the   
   experiment. During the trip no clock synchronization is performed. This   
   is the only (?) correct way to study the behaviour of the individual   
   clocks.   
      
   > 	(To tie this together with the traditional   
   > 	"twin paradox", note that the aging of a person's   
   > 	body is a type of clock.  It's not the most precise   
   > 	of clocks, but that doesn't matter for our   
   > 	/gedanken/ purposes.)   
      
   It is the behaviour of the (moving) clocks during the experiment to   
   mimic the aging of the twins from the start to the end.   
      
   > -- jt]]   
   >   
   > The purpose of this posting is to mention that any experiment which tries   
   > to demonstrate the importance or influence of acceleration is rather complex.   
   > The movement of the objects involves 'gravity' (Newton's Law or GR)   
   > and extra forces in order to control the movement of the spaceships.   
   > ONLY in order to describe the behaviour of the clocks the speed of light   
   > is involved.   
      
   The above mentioned experiment is important because it shows that   
   identical clocks under different circumstances i.e. different path   
   through space, different forces, different accelerations, will behave   
   differently. In this particle setup the forces are rocket propulsion   
   forces and gravity forces. The propulsion forces are used to bring the   
   spaceship (clock) in orbit at the correct distance and with the correct   
   speed. Secondly to bring the spaceship and clock back home, back to   
   earth. The force of gravity is used to keep the speceship in orbit. The   
   same experiment can also be done without a central mass. In that case   
   propulsion forces have to be used to keep the spaceship in 'orbit' In   
   both cases the result will be the same. The spaceship in the closest   
   orbit will run the slowest, relative to the frame of the earth.   
      
   It also should be mentioned that clocks are not governed by laws. All   
   clocks function partly mechanical partly electronic.   
   https://nawcc.org/index.php/just-for-kids/about-time/how-does-it-work In   
   some sense each clock is described by its own set of mathematical   
   equations or laws when it is at rest on earth. Moving clock relative to   
   this rest frame will run slower.   
      
   Nicolaas Vroom.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)