Re: Rigid rod problem

russ...@xxxxxxxx wrote:
> Spoonfed wrote:
> > >
> > > All parts of the rod are traveling at same speed ... but time passes
> > > not synchronously along the rod. Clocks run slower at the back end
>
> I don't see in what sense your first statement could
> be true; it certainly isn't true in the original inertial
> frame, where at all t>0 the rear of the rod is moving a
> tiny bit faster than the front.

By "your" I meant "Kim B's". That is, I knew this was
Kim B's writing but didn't notice that Spoonfed had
provided no attribution. So I am following up, to
clarify.

And also, to make the following correction [after a snip]:

> One thing I do know is true, is that in the original frame
> the rod will always have length L/gamma, where L is the
> original proper length.

Er, this was rather silly of me since I just finished
saying that the rod is moving at different speeds
in this frame -- so which gamma do we use? It seems
there are pitfalls at every turn, in talking about
this.

(Sure, if the acceleration is not great, the statement
is more or less true no matter which gamma we pick,
since they are all about the same. But I think I'd
better stop saying such categorical things about a
problem that I don't even know how to specify exactly.
Indeed it seems like the specification is really the
only hard part here, yet I don't think anyone in this
discussion has seriously addressed that part of it yet.)

.

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