Re: Special Relativity

[Robert Cohen <Robert.Cohen@PO-BOX.ESU.EDU>]

> -----Original Message-----
> From: David Bowman [mailto:dbowman@TIGER.GEORGETOWNCOLLEGE.EDU]
> Sent: Monday, October 28, 2002 12:04 PM
>
> Regarding John Clement's further comments on the twin paradox
> problem:
>
> > While correct it requires that you ignore what happens during the
> > turnaround.  In other words the solution is not complete.  To
> > complete the solution requires GR.
>
> No it doesn't.  Real gravity, i.e. spacetime curvature, doesn't come
> into the problem at all.  SR is perfectly sufficient to analyze what
> happens at the turn around.  We can do it by having a section of the
> problem where the moving twin undergoes a uniform local
> acceleration w.r.t. a sequence of locally coincident comoving
> inertial frames, and then take the limit of the acceleration going
> to infinity while the duration of the acceleration goes to zero.

I haven't had time to follow this thread carefully but I'm confused over
what the "paradox" is.  I thought the "paradox" was not that time is
relative but that according to SR one wouldn't be able to tell which twin
was moving and which was stationary (i.e., GR was needed to handle the fact
that one twin experienced an acceleration and the other didn't).  That one
twin aged and the other didn't implies that motion is not relative, hence
the paradox.

Am I mistaken?

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; 570-422-3428; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.