Re: The Langevin's traveler

On Fri, 2 Aug 2024 14:35:52 +0000, Richard Hachel wrote:

>
Le 02/08/2024 à 16:09, hitlong@yahoo.com (gharnagel) a écrit :

On Thu, 1 Aug 2024 21:14:29 +0000, Richard Hachel wrote:

>

Very pretty pictures but sorry, old friend, they are incorrect.

>
 C'est parfaitement correct.
>

First of all, the time between Earth and Tau Ceti need not be
12 years. Just how would an expedition to TC measure time?
Since a time at TC is specified, we must assume an earlier
expedition arrived there.  One way to set the time there
would be to carry their chronometer with them, which began
the journey synchronized with Earth time.  Let's say they
left Earth in 1960.  At 0.8c, their time of arrival would
be 1969 (ignoring acceleration and deceleration).

>
 Absolutely.
>
I beg you to breathe and blow.
>
When dealing with Dr. Hachel, you must first listen to him
and then respond with control.

Exactly what I have done.  RH should be a little less

It is true that in your example (departure 1960, speed Vo=0.8c)
the rocket will arrive with a watch that will mark 1969.
>
Everyone says the same thing, and so do I.
>
I say that FOR the rocket, the rocket's watch marks 1969.
>
I say that FOR the earth, the rocket's watch marks 1969.
>
That is LOGICAL.
>
BUT two other questions will arise:
>
1. What time is it on earth FOR the rocket when the fact
happens?
2. What time is it on earth FOR the earth when the fact
happens?

Irrelevant at this point in the problem.

These two questions are very different, and already require
much more attention than the first two, because the answers
given are most often wrong (since the bigwigs of physics do
not understand THEIR theory correctly).
>

Earth time would be 1975.  So TC time would be behind Earth

time by 6 years, not 12 years.
>
 No.
>
 You do not understand your own example.
In your example, when the rocket reaches its goal, we neglect
the short-term accelerations, Stella's watch marks 1969. It
crossed the 12 ly in 9 years of proper time.
But the terrestrial watch FOR the earth marks 1987!!!

Nope.  The ship started from Earth in 1960 going 0.8c.  It
traveled 12 LYrs, so according to Earth time it would take
12/.8 = 15 years.  It was 1975 Earth time when the ship
arrived at its destination.  Without tachyon communication,
the Earth couldn't KNOW that until the ship sent a signal
back which traveled at c, which would be in 1987, as I
specified.  At that time, the Earth could calculate that
the ship arrived at its destination 12 years earlier.
1975 is the CORRECT answer when the ship arrived according
to Earth time.

The fact takes place in 1987 (and not in 1975) as one
stupidly thinks when one understands nothing,

RH is overthinking the problem, which I cautioned him not
to do:
 “Don’t think too much.  You’ll create a problem that
wasn’t even there in the first place.” – Anon.

but nothing at all of Hachel's work for 40 years on
the simple and coherent geometry of the RR.
>
R.H.

Only 40 years?  I started working SR problems 64 years ago!
In the meantime I earned engineering, mathematics and physics
degrees.