🚀 go-pugleaf

aguirre@wigner.physics.upenn.edu (Anthony Aguirre) writes:

>    What you're saying is no different than complaining about the first half
> of the standard twins paradox: If the first twin leaves for AC at 99% the
> speed of light, he feels that 7 months have passed, whereas the twin on
> earth would claim that 4 years had passed.  But why not assume that the
> first twin stayed still, the earth moved away at 99% c, thus the earthman
> aged 7 months and the traveller aged 4 years?  This is basically the same
> as the "paradox" you are pointing out.
>
>    The problem, however, is that the twins cannot compare ages until they
> have returned to the same reference frame. The asymmetry occurs when the
> traveler turns around and returns to earth.  If, somehow, the earth (and
> AC) were to turn around so that the earth returned to the traveler, then it
> would turn out that the traveler was younger than the earthman.  Thus,
> symmetry.

     It is not necessary for one of them to turn around or accelerate to make
this comparison.  That just confuses the issue, because then people start to
think that turning around has something to do with who ages how much.  It
does not.  The differential aging occurs in a simple one-way trip without
accelerations, as should be evident in this example.  And when all four
encounters are examined, all possible age comparisons become possible by
direct (not remote) observation.

>    In your example, one of the two reference frames would have to change in
> order for both reference frames to become equivalent and allow a meaningful
> comparison of ages.  Depending on which frame changes, one of the twins
> would end up older than the other in a way similar to the standard twins
> paradox.

     No, meaningful comparisons can be done at each encounter event.
Eventually all combinations are compared.

>    You might object "well, why not compare the ages from a distance."  For
> example, the traveler, upon reaching AC, could send a message home at the
> speed of light, saying "it took me 7 months (my time) to get here."  The
> earth would receive this message four years after it was send (in the
> traveller's frame.)  But his doesn't mean four years in earth's frame.  The
> key to the twins paradox (as in all SR) is being very careful about exactly
> which measurements are being taken, and in which frame, etc.

     See my new posting with the resolution of the paradox.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.