Re: Special Relativity

[Larry Cartwright <exit60@CABLESPEED.COM>]

"John S. Denker" wrote:
> ... any free-falling frame is as good as any other free-falling
> frame, and if they are moving relative to each other you
> can't say which is moving and which is not.
>
> But SR can certainly tell which twin has a single,
> constant velocity and which twin has two velocities
> and switches from one to the other.
>
> Motion is relative.  We can make the frame-independent
> statement that one twin has an outbound velocity that
> is different from his inbound velocity.  That twin's
> two velocities are different RELATIVE TO EACH OTHER.
> The stay-at-home twin has no such velocity-difference.
> That's all that need be said in order to break the
> alleged symmetry, and SR has no problem saying that.

Awesome!  This could be the most clear and concise conceptual summary of
the Twins Scenario I have ever read.  Thank you, John.

Best wishes,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright   <exit60@cablespeed.com>
Retired (June 2001) Physics Teacher
Charlotte MI 48813 USA
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Lord, protect us from the excesses of those
who wish us harm; and protect us from the
excesses of those who would protect us.
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This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.