Re: twin patadox question


slefkowit@xxxxxxx wrote:
> The usual explanation (as I understand it) as to why the twin paradox
> is not really a paradox is that one twin experiences acceleration and
> the other doesn't.
>

Note: A paradox is something that, on the surface appears to be a
contradiction, but on closer examination is discovered not to be a
contradiction.

> Consider the following example:
> spaceship 1 is statinonary
>
> spaceship 2 accelerated to .99c before we began this experiment. It
> passes spaceship 1 and they synchronize their clocks at time 0. It
> travels 10 light years (as measured by spaceship 1).
>
> spaceship 3 has also accerated to .99c before we began the experiment
> and is travelling in the opposite direction from spaceship 2. At the 10
> light year mark (as measured by spaceship 1), '2' and '3' cross paths
> and '2' tells '3' what time it is. '3' continues on, passes '1' and
> reports the time at which it passed '2'. What time does '3' report to
> '1'?
>
> Time dilation (if I calculate correctly) would say '2' should have
> recorded about 1.4 years at the 10 light year mark. But without
> acceleration, '1' and '2' would appear to be in symmetric situations,
> so that '2' should also think about 10 years passed.
>
> What is the correct calculation?

There is indeed symmetry between '1' and '2', but in the end you didn't
compare the clocks of '1' and '2, you compared the clocks of '1' and
'3'; which gives the same result as if you had only two ships and one
turned around. To see this clearly, work out the Lorentz transforms
for your thought experiment.

Paul Cardinale


P.S. Ignore "Sue", "Perspicacious", and "Daryl McCullough". They are
morons who are willfully ignorant of SR.

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