🚀 go-pugleaf

>From: nic.MR.NET!thor!christnp@csd4.milw.wisc.edu  (Doctor X)
>Actually, if I remember correctly, the paradox is resolved without   
>resorting to GR.  The ship and the point in the universe, say a planet,
>are in different reference frames.  In order for the ship to return to
>the planet to compare clocks, etc it has to *switch* reference frames, 
>i.e. decellerate and turn around.  The switching of reference frames 
>solves the paradox.

>In article <7217@venera.isi.edu> rod@venera.isi.edu.UUCP 
>(Rodney Doyle Van Meter III) writes:
>>General relativity teaches that it actually is possible to differentiate
>>the frames of reference.                                             
>>             I believe the acceleration is what does it. 

>I don't believe so.  First, GR is mainly concerned with the consequences
>of having a non-euclidean space-time.  That is its main difference from
>SR.  Second, many people have the misconception that the resolution to the
>twin paradox is due to the *accelleration* of the ship in the above 
>example, but it's really due to the change in frame of reference.

You are making a distinction that doesn't exist. "Acceleration" and
"change in frame of reference" are the same thing. A constant acceleration
represents a continual change in the frame of reference.

According to a general "science and technology" book I have handy, General
Relativity includes the effects of acceleration, gravity, curvature of
space, etc. Special Relativity is a "special case" of General Relativity,
in which these effects can be ignored because all observers and objects
remain in fixed frames of reference. If any of the participants in the
observation undergo "acceleration" or "change in frame of reference",
the conditions of Special Relativity are violated, and the principles
of General Relativity must be used.

(By the way, our college physics course never got around to General
Relativity. Anyone know of a good reference with a moderate amount of
mathematics?)
                                John Roberts
                                roberts@cmr.icst.nbs.gov