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From: hitlong@yahoo.com (gharnagel)
Newsgroups: sci.physics.relativity
Subject: Re: Langevin's paradox again
Date: Thu, 4 Jul 2024 18:27:03 +0000
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Richard Hachel wrote:
>
> Langevin's paradox.
> The Langevin paradox is a very serious criticism against the theory of
> relativity.

No, it's not.  It's only a paradox when part of the operation is
ignored.
That part has been explained in more than one way, but some don't seem
capable of understanding.

> [Verbal bobbling deleted]
>
> What was the grievance?
>
> If the twin of the stars returns younger in the frame of reference of
> the twin who remained on earth, then the twin who remained on earth,
> if we apply the reciprocity of effects, and Doctor Richard Hachel says
> that we must use this notion of reciprocity,

Dr. Hachel is wrong, along with all those who conveniently forget about
the turn-around.  And "reciprocity" doesn't even enter Dr. H's solution.

> very basis of logic, comes back older than the other. Which is both
> logical and absurd.

“No, no, you’re not thinking: you’re just being logical” – Niels Bohr

“Logic is like the sword--those who appeal to it shall perish by it.”
-- Samuel Butler

> No one has ever been able to answer the question correctly and
> perfectly

Incorrect assertion.

> [Self-aggrandizing verbage deleted]
>
> The great problem facing the world's physicists is a problem of
> confusion.
> They confuse two notions: the notion of relativity of measured times,
> and the notion of reciprocal relativity of chronotropies.

Incorrect assertion.

> It's not the same thing.
>
> Hence the impossibility for them all to explain things coherently.

Not impossible.

“There is no point in using the word 'impossible' to describe something
that has clearly happened.” – Douglas Adams

> The relativity of the measured times will show that over a journey of 24
> light years, carried out at v=0.8c, Terrence will age by 30 years.
> It's very simple: x=v.t, i.e. t=x/v and 24[/]0.8=30
> But when Stella returns, she will only be 18 years old[er].

[Corrections made].

> There is therefore an asymmetry, that is obvious, but it is on the
> explanation of the asymmetry that everyone sinks into complete
> ignorance.

Not everyone, and there is more than one way to skin a cat.

> Because we are confusing it with the notion of chronotropy, which is
> ANOTHER THING, and which can be defined by the internal functioning of
> watches. On this, yes, the effect is symmetrical, reciprocal; each
> watch, and throughout the entire journey, (including if I place a small
> half-turn phase on a semi-circle with a preserved tangential speed of
> 0.8c), beats faster than the other watch, and the equation is constant
> and reciprocal over the entire path: T2=T1/sqrt(1-v²/c²).
>
> This is true.
>
> But this only qualifies chronotropy, that is to say the internal
> mechanism of watches, it is not the whole of the relativistic effect.
>
> This is not what we will ultimately measure.
>
> I can't explain it more clearly.

Then you have failed.  Whether the entire path a semicircle, or just the
end is a semicircle, particle physicists have known for nearly a century
that time dilation occurs on circular paths based only on the velocity
around the path.  So Dr. hachel is a few years too late.

If the semicircle is at the end of a straightaway, then Stella will
endure
a humongous acceleration and return home a puddle of goo.  If, OTOH, her
trajectory is a giant circle of 24 Lyrs circumference, she will, indeed,
be 6 years younger than her twin, but if she wanted to reach a
destination
24 LYrs AWAY, she will only reach a distance of 7.6 Lyrs from home.

Usually, the problem is proposed as reaching a destination along a
linear
path and then returning, not taking a grand tour.