Re: Hewitt Special Relativity Example (Long)

[Glenn Knapp <kahuna@VCN.COM>]

At 11:53 AM 10/24/2002 -0700, you wrote:
> Carl E. Mungan wrote:
>
> If the frequency is shifted by a factor of r when an observer moves
> away from (or toward) a source at a speed v, then the frequency will
> be shifted by a factor of 1/r when the source moves toward (or away
> from) the observer at the same speed v.
>
> An examination of the equations for the "normal" and relativistic
> Doppler effects will show that both support this conclusion.  The
> critical difference--one that needs to be made explicit to apply the
> argument to Hewitt's treatment of the twin paradox in which the
> observer is always "at rest"--is that, in the case of the
> relativistic Doppler effect, motion of the source is
> indistinguishable from motion of the observer.

> I've read Hewett's explanation for the twin paradox and must agree with
> Carl's posting (up above).  The thing that I do not see in Hewett's
> explanation is the correlation betwen the frequency difference and the
> time between the pulses experienced by the earth observer with the actual
> passage of time aboard the spacecraft or on the earth.  I have difficulty
> seeing how this brings about time dillation on the spacecraft.


I recall reading (sorry, can't cite the source) that the time dilation in
the spacecraft is a result of its acceleration, which the stationary earth
does not experience.  The idea being that the spacecraft and the earth are
not two different reference frames moving away or towards one another at a
constant velocity.  One is an accelerated frame (at least at some point on
the voyage) and the other is not.

So what is the actual, copper-bottomed, good to go, widely accepted
explanation for the twin paradox?

G.W. Knapp

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