Date: Sat, 18 Jan 2025 23:08:22 +0100
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Subject: Re: Understanding the theory of special relativity
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W dniu 18.01.2025 o 20:28, Paul.B.Andersen pisze:
> Den 18.01.2025 10:04, skrev Richard Hachel:
>> Le 17/01/2025 à 13:30, "Paul.B.Andersen" a écrit :
>>>
>>> Stella is in a rocket and is co-located with Terrence when
>>> she starts her rocket engine and accelerates at 1 c/year
>>> away from Terrence for 2.25 year on her clock.
>>> Then she turns her rocket around and accelerates at 1 c/year
>>> towards Terrence for 4.5 years.
>>> Then she turns her rocket around and accelerates (brakes) at 1 c/year
>>> away from Terrence for 2.25 years.
>>>
>>> When Stella is back at Terrence both stop their watches.
>>> They are now co-located and stationary to each other.
>>> Their clocks are side by side and can easily be compared.
>>> Terrence clock shows 23.7 years.
>>> Stella's watch shows 9 years.
>>
>> In the problem you pose:
>> A rocket leaves the earth and accelerates (a=1ly/year).
>> This during a proper time Tr (or tau) = 2.25 years.
>> Which gives a total of Tr=9 years.
> 
> It is the very same as this scenario:
> https://paulba.no/pdf/TwinsByMetric.pdf
> See: 2.2 B travels with constant speed and instant acceleration
> And: 2.4 Concrete example
> 
> This is what SR predicts:
> 
> When Terrence (Twin A) is back, his watch show 23.664 y ≈ 23.7 y
> When Stella is back (Twin B), her watch show 9.912y ≈ 9 y
> (bad round off, but doesn't really matter)

This is what SR predicts, and anyone can check
GPS - it has nothing in commom with real clocks.