Le 15/11/2022 à 12:30, Mikko a écrit :
> On 2022-11-14 20:29:52 +0000, Richard Hachel said:
>
>> In the example that you take, and which is that of the Langevin twins,
>> the twins use several reference frames.
>
> ...
>
>> Yet they don't have the same space-time path, I agree.
>>
>> But they will have the same spatial path, and the same starting and
>> ending spatial coordinates in all the reference frames of the universe.
>
> In almost every coordinate system one of the twins has a bent or curved
> path and the other has a straight path.
>
> How can a bent or curved path be the same as a straight path?
>
> Mikko

I'm not talking about the same temporo-spatial "line".

I'm talking about the same spatial trajectory, and the same final proper
time in this very precise case (and even extremely precise and
well-defined, because you have to be wary of variants).

It is obvious that the two travelers who are in different rockets, will
have "different temporo-psacial trajectories" since not once, except at
departure and arrival, will they be in the same space location.

What I'm saying is that, in this very precise case, however, at the
finish, their own final times will be equal.

Tr=4.776 years.

Same for To, To=12.915 years for both.

R.H.

On Tuesday, November 15, 2022 at 4:35:40 AM UTC-8, Richard Hachel wrote:
> >> the example that you take is that of the Langevin twins…
> >> I am not talking about this example, but about the traveler
> >> of Tau Ceti,
> >
> > The two example are the same, merely described in terms of different coordinate
> > systems. In both cases we have twins who separate at the departure event, and one
> > of them moves without acceleration to the reunion event, whereas the other moves
> > with some acceleration. Look at these two examples:
> >
> > Langevin: One twin is stationary at the origin for 2 hours of coordinate time,
> > and the other twin moves at -5 mph for 1 hour of coordinate time and then abruptly
> > accelerates and moves at +5 miles for 1 hour of coordinate time.
> >
> > Tau Ceti: One twin moves at 10 mph for 2 hours of coordinate time, and the
> > other twin moves at 5 mph for 1 hour of coordinate time, and then abruptly
> > accelerates and moves at 15 mph for 1 hour of coordinate time.
> >
> > Note that these two scenarios are exactly the same, merely described in terms of
> > two different coordinate systems. However, according to your beliefs, in the
> > first description the twins have unequal proper times whereas in the latter
> > description they have equal proper times. This is self-contradictory, so your
> > beliefs are absurd.
> >
> > You will complain: No! My rocket accelerates continuously, not abruptly! But
> > that is an invalid complaint, because we can just as well use a smoothly
> > accelerating twin as an abruptly accelerating one, both for Langevin and for Tau
> > Ceti. Thus, your beliefs are absurd, and none of your pointless attempts to evade
> > logic have any validity.
>
> These are not the same examples.

Yes they are. The Tau Ceti example has the inertial twin moving at constant speed +12/12.915 while the accelerating twin begins at rest, but we can just as well describe this situation in terms of a frame in which the inertial twin is at rest and the accelerating twin begins with velocity -12/12.915. This shows one twin remaining at rest the entire time, and the other moving away and coiming back, which is the Langevin twin situation. Whether the acceleration is smooth or abrupt is just a detail, not affecting whether the twins have the same total elapsed time or not.

To help you understand this, please state whether the elapsed proper times are the same for the twins in each of the following scenarios:

Example 1: One twin is stationary at the origin for 2 hours of coordinate time, and the other twin moves at -5 mph for 1 hour of coordinate time and then abruptly accelerates and moves at +5 mph for 1 hour of coordinate time.

Example 2: One twin moves at 10 mph for 2 hours of coordinate time, and the other twin moves at 5 mph for 1 hour of coordinate time, and then abruptly accelerates and moves at 15 mph for 1 hour of coordinate time.

On 2022-11-15 12:55:37 +0000, Richard Hachel said:

> Le 15/11/2022 à 12:30, Mikko a écrit :
>> On 2022-11-14 20:29:52 +0000, Richard Hachel said:
>>
>>> In the example that you take, and which is that of the Langevin twins,
>>> the twins use several reference frames.
>>
>> ...
>>
>>> Yet they don't have the same space-time path, I agree.
>>>
>>> But they will have the same spatial path, and the same starting and
>>> ending spatial coordinates in all the reference frames of the universe.
>>
>> In almost every coordinate system one of the twins has a bent or curved
>> path and the other has a straight path.
>>
>> How can a bent or curved path be the same as a straight path?
>>
>> Mikko
>
> I'm not talking about the same temporo-spatial "line".

Instead of talking about what you are not talking about youshould answer
the question: How can a bent or curved spatial trajectory be the same as
a straight spatial trajectory?

But you don't answer because you can't. You can't answer because you don't
understand what you are talking about.

Mikko

On Tuesday, 15 November 2022 at 15:18:35 UTC+1, Stan Fultoni wrote:
> On Tuesday, November 15, 2022 at 4:35:40 AM UTC-8, Richard Hachel wrote:
> > >> the example that you take is that of the Langevin twins…
> > >> I am not talking about this example, but about the traveler
> > >> of Tau Ceti,
> > >
> > > The two example are the same, merely described in terms of different coordinate
> > > systems. In both cases we have twins who separate at the departure event, and one
> > > of them moves without acceleration to the reunion event, whereas the other moves
> > > with some acceleration. Look at these two examples:
> > >
> > > Langevin: One twin is stationary at the origin for 2 hours of coordinate time,
> > > and the other twin moves at -5 mph for 1 hour of coordinate time and then abruptly
> > > accelerates and moves at +5 miles for 1 hour of coordinate time.
> > >
> > > Tau Ceti: One twin moves at 10 mph for 2 hours of coordinate time, and the
> > > other twin moves at 5 mph for 1 hour of coordinate time, and then abruptly
> > > accelerates and moves at 15 mph for 1 hour of coordinate time.
> > >
> > > Note that these two scenarios are exactly the same, merely described in terms of
> > > two different coordinate systems. However, according to your beliefs, in the
> > > first description the twins have unequal proper times whereas in the latter
> > > description they have equal proper times. This is self-contradictory, so your
> > > beliefs are absurd.
> > >
> > > You will complain: No! My rocket accelerates continuously, not abruptly! But
> > > that is an invalid complaint, because we can just as well use a smoothly
> > > accelerating twin as an abruptly accelerating one, both for Langevin and for Tau
> > > Ceti. Thus, your beliefs are absurd, and none of your pointless attempts to evade
> > > logic have any validity.
> >
> > These are not the same examples.
> Yes they are. The Tau Ceti example has the inertial twin moving at constant speed +12/12.915 while the accelerating twin begins at rest, but we can just as well describe this situation in terms of a frame in which the inertial twin is at rest and the accelerating twin begins with velocity -12/12.915. This shows one twin remaining at rest the entire time, and the other moving away and coiming back, which is the Langevin twin situation. Whether the acceleration is smooth or abrupt is just a detail, not affecting whether the twins have the same total elapsed time or not.

And in the meantime in the real world, forbidden
by your bunch of idiots GPS and TAI keep
measuring t'=t in forbidden by your bunch of
idiots old seconds.

Le 15/11/2022 à 16:57, Maciej Wozniak a écrit :
> On Tuesday, 15 November 2022 at 15:18:35 UTC+1, Stan Fultoni wrote:

> measuring t'=t

Tu l'as déjà dit, ça.

Il faut que tu parles d'autres choses.

R.H.

On Tuesday, November 15, 2022 at 9:30:11 AM UTC-8, Richard Hachel wrote:
> These are not the same examples.

Yes they are. The Tau Ceti example has the inertial twin moving at constant speed +12/12.915 while the accelerating twin begins at rest, but we can just as well describe this situation in terms of a frame in which the inertial twin is at rest and the accelerating twin begins with velocity -12/12.915.. And whether the acceleration is smooth or abrupt is just a detail, not affecting whether the twins have the same total elapsed time or not. To clarify your beliefs, consider these two examples:

- Example 1: One twin is stationary at the origin for 2 hours, and the other twin moves at -5 mph for 1 hour and then abruptly accelerates and moves at +5 mph for 1 hour.

- Example 2: One twin moves at 10 mph for 2 hours, and the other twin moves at 5 mph for 1 hour, and then abruptly accelerates and moves at 15 mph for 1 hour.

Please state whether the elapsed proper times are the same for the twins in each example.

On 11/14/2022 9:13 AM, Richard Hachel wrote:
> Le 14/11/2022 à 06:29, Volney a écrit :
>> On 11/13/2022 12:13 PM, Richard Hachel wrote:
>>> Le 13/11/2022 à 17:57, Volney a écrit :
>>
>>>> So you agree they don't take the same paths through spacetime.
>>>
>>> That's what I keep saying.
>>>
>>> They follow the same path, in space.
>>>
>>> But not in space-time, since I begged millions of physicists to tell
>>> the difference (but they're too dumb, it's horrible).
>>
>> Since you agree they don't follow the same path through spacetime, the
>> two travelers will experience different proper times. And the proper
>> time of one traveler should not be using the formula of the other
>> traveler, and your original claim is wrong.
>
>
> That's not what I'm saying.
>
> This is what relativistic physicists say, based on a poor understanding
> of Lorentz transformations, and have imagined a space-time block in four
> dimensions, one of which is more or less "complex".
>
> What I say myself, and what I ask that we not distort (it is very
> tempting to distort what an "opponent" says to try to have a hold), is
> that if the space crossed (simple threeD) is the same, and if the
> departures and the arrivals take place simultaneously, not only the
> observable times will be equal to each other (tautology), but also, the
> proper times will be equal to each other.

But in SR there's zero evidence of that. In fact the SR math shows that
is generally false as the integration shows.
>
> I repeat, I do not use the same space-time as other physicists,

So you also play "let's pretend". If you want to go *anywhere* with
this, you'll need to define your 'different' spacetime as well as
explain why your 'different' spacetime is valid and why the 'old'
spacetime is invalid.

Meanwhile, you shouldn't refer to the Lorentz transformation since SR
math ("the 'old' spacetime") has identical math as it does.

> and in
> the end, I sometimes say very different things than experimentation
> will prove theoretical consistency, I am sure.

You need to define your "different" spacetime. You always refer to
spacetime which would mean ordinary SR and then you make claims which
are inconsistent with SR.