[Phys-L] Re: "moving clock runs slower" (not)

[John Denker <jsd@AV8N.COM>]

Rick Tarara wrote:

> Is the twin who made the near-light-speed trip really younger when he
> returns?

Yes, he is ... by any reasonable definition of "younger".

>  If he is, didn't his clock HAVE to run slow

No.

I discuss this point in my writeup:
   http://www.av8n.com/physics/twins.htm#sec-space-time

That section concludes by saying
   In the non-relativistic limit, the notion of “elapsed time from A to B”
   is well defined, and is the same for all observers ... but in general,
   i.e. if some observers are moving at relativistic speeds, then the
   elapsed time is just as path-dependent as the mileage.
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