From: heathjohn2@gmail.com   
      
   On Friday, August 4, 2017 at 2:47:57 AM UTC-4, LuigiFortunati wrote:   
   > Roland Franzius alle ore 08:54:12 del 03/08/2017 ha scritto:   
   >>> The traveling twin starts and goes back to Earth where he finds his   
   >>> 80-year-old brother aged as he is only 10 years old.   
   >>>   
   >>> The wristwatch on the twin traveler's wrist marks (of course) the   
   >>> 10-year time.   
   >>>   
   >>> The earth twin during the years of the trip has been flashing every 10   
   >>> years (his).   
   >>>   
   >>> The last lightning is emitted at the time of the return of the ship,   
   >>> when the Earth clock marks the 80-year time and the wrist watch on   
   >>> the twin traveler marks 10 years.   
   >>>   
   >>> Calculation (perhaps) impossible is this: at the ejection of the   
   >>> penultimate lightning (when the Earth clock marked 70 years) what time   
   >>> was the watch on the wrist of the traveling twin?   
   >>>   
   >>   
   >> There is a Lorentz frame (t,x) of the sun at rest. The orbiting earth as a   
   rotating light house at constant angular speed emits a flash every year. This   
   flash is represented by a series of immediate time-forward cones   
   (t-k)^2=x^2+y^2+z^2, t>k, k=0,1,2.   
   . and so on covering the inner of the first flasch cone over all of space-time.   
   >>   
   >> Any traveller starting at (t,x,y,z)=0 and returning to that straight world   
   line at a point later (k,0,0,0) on a continous path intersects each forward   
   light cone once.   
   >>   
   >> This is the kernel of causality: In a flat universe without timelike closed   
   world lines one cannot miss a light flash signal and one cannot catch a signal   
   twice as long as on moves on timelike world lines.   
   >>   
   >> The inverse is also true: The traveller moving outward on a straight world   
   line flashes a signal each year and each signal reaches earth before his   
   arrival back home. The the same with the inward travel.   
   >>   
   >> The relative clock rates are given by the (hyperbolic functions of the)   
   angles, by which the world lines of earth and traveller intersect the flash   
   cone surfaces.   
   >>   
   >> As Minkowski told us, you never may grasp and imagine the simple laws of   
   the special relativistic kinematics, if you dont switch from meter sticks,   
   3d-curves and clocks to the picture of world lines in fourdimensional   
   space-time with a vector norm    
   representing the lenght of a time intervall of a tangent vector.   
   >>   
   >> This is very similar to the complexity considering curves as y=f(x) like   
   Kepler did for planets instead of the trivial vector representation in a plane   
   (x(t),y(t)) as has been considered by Newton.   
   >   
   > Ok.   
   >   
   > But I ask for a very simple thing to which you did not answer: what time   
   > marks the twin traveler watch when a terrestrial brother emits his   
   > penultimate ray?   
   >   
   > --   
   > Luigi Fortunati   
   >   
   > Credere e' piu' facile che pensare   
   > Believing is easier than thinking   
      
   I have heard this same debate so many time by some fine minds. It always   
   ends up somewhat like dogs barking at the moon. The main problem is   
   having too many variable on the table at the same time.   
      
   A} Newtonian Doppler effect leading to red or blue shift   
      
   B] Time delay of c   
      
   C] Relativistic time dilation caused by movement   
      
   There is a way to boil it down to relativistic time dilation only.   
      
   One observer only place at mid point between S and T   
      
   He will know if clocks are synchronized or not regardless of distance as   
   he is in at mid point between S ant T.   
      
   We must only ask the mid point observer before the traveling twin leaves   
   or after the traveling twin arrives. Any questions asked while the   
   traveling twin is moving will only lead to confusion over Doppler , red   
   shift blue shift , time dilation and simultaneity of time. This is where   
   most of such debates break down into dogs barking at the moon as there   
   are too many variables on the table at the same time.   
      
   At best all that can be said is the traveling twin's clock has lost time   
   between S to T that is tracking SR. Not necessarily a Minkowki   
   interpretation of SR where time is required to jump at some point from   
   different observers but it is tracking SR in the general sense of time   
   dilation caused by movement that approaches c.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)