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From: "Paul.B.Andersen" <relativity@paulba.no>
Newsgroups: sci.physics.relativity
Subject: Re: Langevin's paradox again
Date: Fri, 12 Jul 2024 15:29:20 +0200
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Den 11.07.2024 20:29, skrev Richard Hachel:
> 
> < snip whining and heavy breathing >
> 
> 
> I repeat, during the U-turn, nothing happens at all on the TIME side.

Except that TIME is passing?

> 
> For Terrence to stay on earth, he observed in his ultra-powerful 
> telescope Stella traveling an immense semi-circle at the tangential 
> speed of 0.8c, and returning to earth.
> 
> We admit that the rocket can withstand these terrible accelerations,
> and Terrence observes that the U-turn takes place in 40 hours.
> 
> For Stella, the clean time is shorter, only 24 hours.

Got it.
Stella ages 24 hours while Terrence ages 40 hours during the U-turn.

> 
> But what happens during this U-turn for Terrence?
> He ages by 40 hours, and observes that his sister ages by 24 hours 
> between the moment she begins the U-turn, and the moment she completes 
> her U-turn.

Why the repetition?

> 
> FOR Stella, it's exactly the same thing, when she begins her U-turn, her 
> clock marks 9 years, and she sees over there (direct-live) Terrence's 
> clock marks three years.

When Stella's clock shows 9 hours, Terrence's must show 15 hours.
The distance must be 12 light hours, so the light that Stella  sees
must have left Terrence 12 years earlier, when Terrence clock
showed 3 hours.

OK.

> 
> When she finishes her U-turn, she has aged 24 hours, and she sees the 
> earth clock which still marks three years (plus 40 hours).

So when she see the earth clock it _still_ shows 43 hours? :-D

Terrence's clock must show 55 hours, and since the light will use
12 years to reach Stella, she will see Terrence's clock show 43 hours.

> 
> Nothing special happens.

Right.
Terrence will age another 15 hours, and Stella will age
another 9 hours during  her way back.
So when they are co-located, Stella will have aged 42 hours
while Terrence have aged 70 hours.

Stella has travelled with the speed 0.8c for 70 hours in Terrence'
rest frame and will have aged 70/γ = 42 hours

Note that for the twins to meet again, at least one of must accelerate
during the journey. And for the twins to age differently, their 
acceleration history must be different.

> 
> And those who say that something is happening (like gap-time) are morons 
> who don't understand the theory.

Has anybody said that something is happening?

What was your point?


> 
> Being an idiot who doesn't understand doesn't matter, personally I 
> remained an idiot for decades before I got the hang of it and was able 
> to write an SR of perfect logic and perfect beauty.

So why do you claim that SR is wrong?

-- 
Paul

https://paulba.no/