The train paradox.
Everyone knows this paradox.
A train is running on a 0.8c railway line.
The train measures 500 meters at rest.
In the terrestrial frame of reference, it measures only 300 meters.
We will then place a bridge over which he must pass, but this bridge is
not finished. Lack of 500 meters for the connection.
In the train's frame of reference, the train measures 500 meters, and the
hole 300 meters.
By some means, we make sure that either the train will be able to pass, or
it will not be able to.
We imagine that if at least part of the train touches the rail, it will be
kept on the track (gravitational or electric effect, etc.).
However, in the train's frame of reference, the train will pass.
In the terrestrial frame of reference, it will fall into the ravine (450
deaths).
two incompatible ideas cannot exist together, and all the frames of
reference are necessarily right for them. Except that you have to find a
rotten repository. But which one is it, if one is not absurd?

R.H.

Le 09/12/2021 à 12:26, Richard Hachel a écrit :
> The train paradox.
> Everyone knows this paradox.
> A train is running on a 0.8c railway line.
> The train measures 500 meters at rest.
> In the terrestrial frame of reference, it measures only 300 meters.
> We will then place a bridge over which he must pass, but this bridge is not
> finished. Lack of 500 meters for the connection.
> In the train's frame of reference, the train measures 500 meters, and the hole
> 300 meters.
> By some means, we make sure that either the train will be able to pass, or it
> will not be able to.
> We imagine that if at least part of the train touches the rail, it will be kept
> on the track (gravitational or electric effect, etc.).
> However, in the train's frame of reference, the train will pass.
> In the terrestrial frame of reference, it will fall into the ravine (450
> deaths).
> two incompatible ideas cannot exist together, and all the frames of reference
> are necessarily right for them. Except that you have to find a rotten repository.
> But which one is it, if one is not absurd?
>
> R.H.

Even more astonishing: In the same terrestrial reference frame, an
observer placed at the level of the departure station, will see a train
which measures only approximately 170 m (while the hole measures 500
meters), and thinks that it will fall. Another, placed on the other side
of the bridge, will see a train that measures 1500 meters, and he is
convinced that there is three times the place to pass.
Even better.
In the train's repository, a passenger is sure to die when they see the
bridge arriving. But he is sure that he "could not die" after crossing the
bridge (if at all he crosses it).
Who is right about these six different observations, made by different
observers, three of which are of a mortal opinion, and three of a
confident opinion.

R.H.

Richard Hachel <r.hachel@tiscali.fr> wrote:

> The train paradox.
> Everyone knows this paradox.
> A train is running on a 0.8c railway line.
> The train measures 500 meters at rest.
> In the terrestrial frame of reference, it measures only 300 meters.
> We will then place a bridge over which he must pass, but this bridge is
> not finished. Lack of 500 meters for the connection.
> In the train's frame of reference, the train measures 500 meters, and the
> hole 300 meters.
> By some means, we make sure that either the train will be able to pass, or
> it will not be able to.
> We imagine that if at least part of the train touches the rail, it will be
> kept on the track (gravitational or electric effect, etc.).
> However, in the train's frame of reference, the train will pass.
> In the terrestrial frame of reference, it will fall into the ravine (450
> deaths).
> two incompatible ideas cannot exist together, and all the frames of
> reference are necessarily right for them. Except that you have to find a
> rotten repository. But which one is it, if one is not absurd?

This one is better known as 'the ladder paradox'.
There is an excellent discussion of it on Wikipedia,
complete with space-time diagrams.
<https://en.wikipedia.org/wiki/Ladder_paradox>

Try to understand it,

Jan

Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :

> Try to understand it,

First try to let go of your stinky arrogance.

> Jan

R.H.

On 09-Dec-21 10:26 pm, Richard Hachel wrote:
> The train paradox.
> Everyone knows this paradox.
> A train is running on a 0.8c railway line.
> The train measures 500 meters at rest.
> In the terrestrial frame of reference, it measures only 300 meters.
> We will then place a bridge over which he must pass, but this bridge is
> not finished. Lack of 500 meters for the connection.
> In the train's frame of reference, the train measures 500 meters, and
> the hole 300 meters.
> By some means, we make sure that either the train will be able to pass,
> or it will not be able to.
> We imagine that if at least part of the train touches the rail, it will
> be kept on the track (gravitational or electric effect, etc.).

You can't just claim that the effects are whatever is required to create
your 'paradox'.

In both frames the train takes on the order of a microsecond to cross
the gap. The train will accelerate downwards due to gravity, falling a
negligible distance during that time. So in both frames the train will
have no difficult making the crossing.

Sylvia.

Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :

> <https://en.wikipedia.org/wiki/Ladder_paradox>

All of this does not answer the question I asked at all.

> Jan

What's happens for the train?

R.H.

Le 09/12/2021 à 13:18, Sylvia Else a écrit :
> On 09-Dec-21 10:26 pm, Richard Hachel wrote:
>> The train paradox.
>> Everyone knows this paradox.
>> A train is running on a 0.8c railway line.
>> The train measures 500 meters at rest.
>> In the terrestrial frame of reference, it measures only 300 meters.
>> We will then place a bridge over which he must pass, but this bridge is
>> not finished. Lack of 500 meters for the connection.
>> In the train's frame of reference, the train measures 500 meters, and
>> the hole 300 meters.
>> By some means, we make sure that either the train will be able to pass,
>> or it will not be able to.
>> We imagine that if at least part of the train touches the rail, it will
>> be kept on the track (gravitational or electric effect, etc.).
>
> You can't just claim that the effects are whatever is required to create
> your 'paradox'.
>
> In both frames the train takes on the order of a microsecond to cross
> the gap. The train will accelerate downwards due to gravity, falling a
> negligible distance during that time. So in both frames the train will
> have no difficult making the crossing.
>
> Sylvia.

Do you put dust under the carpet when you clean your house?
This is what most relativistic theorists have been doing with me for
decades.
Since they do NOT want to argue with me because I terrify them, they put
dust under the carpet.
And when I ask a question, they always do like that.
It allows them not to show their incompetence.
At worst, they overwhelm me with insults or contempt.
But they never answer the questions correctly.
Never.
Well almost. Let's be honest, there are people out there who try to do it
right. But there aren't many.

R.H.

On 09-Dec-21 11:32 pm, Richard Hachel wrote:
> Le 09/12/2021 à 13:18, Sylvia Else a écrit :
>> On 09-Dec-21 10:26 pm, Richard Hachel wrote:
>>> The train paradox.
>>> Everyone knows this paradox.
>>> A train is running on a 0.8c railway line.
>>> The train measures 500 meters at rest.
>>> In the terrestrial frame of reference, it measures only 300 meters.
>>> We will then place a bridge over which he must pass, but this bridge
>>> is not finished. Lack of 500 meters for the connection.
>>> In the train's frame of reference, the train measures 500 meters, and
>>> the hole 300 meters.
>>> By some means, we make sure that either the train will be able to
>>> pass, or it will not be able to.
>>> We imagine that if at least part of the train touches the rail, it
>>> will be kept on the track (gravitational or electric effect, etc.).
>>
>> You can't just claim that the effects are whatever is required to
>> create your 'paradox'.
>>
>> In both frames the train takes on the order of a microsecond to cross
>> the gap. The train will accelerate downwards due to gravity, falling a
>> negligible distance during that time. So in both frames the train will
>> have no difficult making the crossing.
>>
>> Sylvia.
>
> Do you put dust under the carpet when you clean your house?
> This is what most relativistic theorists have been doing with me for
> decades.
> Since they do NOT want to argue with me because I terrify them, they put
> dust under the carpet.
> And when I ask a question, they always do like that.
> It allows them not to show their incompetence.
> At worst, they overwhelm me with insults or contempt.
> But they never answer the questions correctly.
> Never.
> Well almost. Let's be honest, there are people out there who try to do
> it right. But there aren't many.
>
> R.H.

You posit a scenario that you think will lead to a contradiction. But to
get the contradiction, you have to engage in hand-waving. It's hardly
compelling, and when we look at what would actually happen, we discover
that the train is, for all practical purposes, unaffected by the gap.

So then you start your customary whining.

Sylvia.

Le 09/12/2021 à 13:45, Sylvia Else a écrit :

> So then you start your customary whining.

It's true.
I like to moan.
We then hear moans, and long lamentations.
It is totally true.
I do not contradict.
The problem is, I am inconsolable. Snifff ...
Why? Sniffff ...
Why this life so cruel to me? Resniffff ...
Do you know that?

R.H.

On Thursday, 9 December 2021 at 12:56:42 UTC+1, J. J. Lodder wrote:
> Richard Hachel <r.ha...@tiscali.fr> wrote:
>
> > The train paradox.
> > Everyone knows this paradox.
> > A train is running on a 0.8c railway line.
> > The train measures 500 meters at rest.
> > In the terrestrial frame of reference, it measures only 300 meters.
> > We will then place a bridge over which he must pass, but this bridge is
> > not finished. Lack of 500 meters for the connection.
> > In the train's frame of reference, the train measures 500 meters, and the
> > hole 300 meters.
> > By some means, we make sure that either the train will be able to pass, or
> > it will not be able to.
> > We imagine that if at least part of the train touches the rail, it will be
> > kept on the track (gravitational or electric effect, etc.).
> > However, in the train's frame of reference, the train will pass.
> > In the terrestrial frame of reference, it will fall into the ravine (450
> > deaths).
> > two incompatible ideas cannot exist together, and all the frames of
> > reference are necessarily right for them. Except that you have to find a
> > rotten repository. But which one is it, if one is not absurd?
> This one is better known as 'the ladder paradox'.
> There is an excellent discussion of it on Wikipedia,
> complete with space-time diagrams.
> <https://en.wikipedia.org/wiki/Ladder_paradox>
>
> Try to understand it,

In the meantime in the real world, however, forbidden
by your insane religion GPS clocks keep measuring t'=t,
just like all serious clocks always did. Try to understand
it.

Le 09/12/2021 à 12:26, Richard Hachel a écrit :
> The train paradox.
> Everyone knows this paradox.
> A train is running on a 0.8c railway line.
> The train measures 500 meters at rest.
> In the terrestrial frame of reference, it measures only 300 meters.
> We will then place a bridge over which he must pass, but this bridge is not
> finished. Lack of 500 meters for the connection.
> In the train's frame of reference, the train measures 500 meters, and the hole
> 300 meters.
> By some means, we make sure that either the train will be able to pass, or it
> will not be able to.
> We imagine that if at least part of the train touches the rail, it will be kept
> on the track (gravitational or electric effect, etc.).
> However, in the train's frame of reference, the train will pass.
> In the terrestrial frame of reference, it will fall into the ravine (450
> deaths).
> two incompatible ideas cannot exist together, and all the frames of reference
> are necessarily right for them. Except that you have to find a rotten repository.
> But which one is it, if one is not absurd?
>
> R.H.

If your little cousin Samantha (9) is on the train, I'm sure you wouldn't
take a joke about it.
You would be much, much, much less lazy and arrogant.
Because that's the problem with scientists, they're arrogant and lazy.
When they don't know how to answer, always, always, always, they put dust
under the carpet, either by referring to stupid sites (so as not to have
to answer themselves) or by insulting the arguer.
It is always the same system that is put in place.
We dare not speak the truth. Namely that we are incompetent and lazy, and
that we do not know (incompetence), or that we do not want (laziness) to
answer.

It's true or it's not true?

R.H.

On 12/9/2021 7:11 AM, Richard Hachel wrote:
> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>
>> Try to understand it,
>
> First try to let go of your stinky arrogance.
>
You are the arrogant one around here, you know.You couldn't even post
the question without implications of SR being 'rotten' and 'absurd'.
(this is actually mild for you)

On 12/9/2021 6:26 AM, Richard Hachel wrote:
> The train paradox.

[...]

> We imagine that if at least part of the train touches the rail, it will
> be kept on the track (gravitational or electric effect, etc.).
> However, in the train's frame of reference, the train will pass.
> In the terrestrial frame of reference, it will fall into the ravine (450
> deaths).
> two incompatible ideas cannot exist together, and all the frames of
> reference are necessarily right for them.

The problem with that analysis is that you implicitly assume that there
is some sort of infinite speed communication of the front and rear of
the train with each other so that the train can 'decide' to fall into
the gap if and only if both ends are not supported. Then you point out
how in one frame both ends are unsupported and in another they never are
both unsupported. Paradox. However, there is no such infinite speed
communication. The front of the train can only 'know' about the
situation of the rear as it was 500/c seconds ago. Same for the bridge,
one end can only 'know' about the situation of the other end as it was
500/c seconds ago. This is much like the bug/rivet 'paradox' which
isn't a paradox if you remember it takes a finite time for the event of
the rivet head reaching the wall to reach the tip, so the bug is always
squashed.

Richard Hachel <r.hachel@tiscali.fr> wrote:
> The train paradox.
> Everyone knows this paradox.
> A train is running on a 0.8c railway line.
> The train measures 500 meters at rest.
> In the terrestrial frame of reference, it measures only 300 meters.
> We will then place a bridge over which he must pass, but this bridge is
> not finished. Lack of 500 meters for the connection.
> In the train's frame of reference, the train measures 500 meters, and the
> hole 300 meters.
> By some means, we make sure that either the train will be able to pass, or
> it will not be able to.
> We imagine that if at least part of the train touches the rail, it will be
> kept on the track (gravitational or electric effect, etc.).
> However, in the train's frame of reference, the train will pass.
> In the terrestrial frame of reference, it will fall into the ravine (450
> deaths).
> two incompatible ideas cannot exist together, and all the frames of
> reference are necessarily right for them. Except that you have to find a
> rotten repository. But which one is it, if one is not absurd?
>
> R.H.
>

This is a variation of a very old and traditional puzzle called the “ladder
problem” or “rod and grate problem”. Puzzles like this are used over and
over again in textbooks about relativity, and students are encouraged to
read those textbooks to understand why they are not irreconcilable
contradictions.

You would do yourself a great service by looking through some of those
books to learn more about the basics of relativity. Bon chance!

--
Odd Bodkin -- maker of fine toys, tools, tables

Richard Hachel <r.hachel@tiscali.fr> wrote:
> Le 09/12/2021 à 12:26, Richard Hachel a écrit :
>> The train paradox.
>> Everyone knows this paradox.
>> A train is running on a 0.8c railway line.
>> The train measures 500 meters at rest.
>> In the terrestrial frame of reference, it measures only 300 meters.
>> We will then place a bridge over which he must pass, but this bridge is not
>> finished. Lack of 500 meters for the connection.
>> In the train's frame of reference, the train measures 500 meters, and the hole
>> 300 meters.
>> By some means, we make sure that either the train will be able to pass, or it
>> will not be able to.
>> We imagine that if at least part of the train touches the rail, it will be kept
>> on the track (gravitational or electric effect, etc.).
>> However, in the train's frame of reference, the train will pass.
>> In the terrestrial frame of reference, it will fall into the ravine (450
>> deaths).
>> two incompatible ideas cannot exist together, and all the frames of reference
>> are necessarily right for them. Except that you have to find a rotten repository.
>> But which one is it, if one is not absurd?
>>
>> R.H.
>
> Even more astonishing: In the same terrestrial reference frame, an
> observer placed at the level of the departure station, will see a train
> which measures only approximately 170 m (while the hole measures 500
> meters), and thinks that it will fall. Another, placed on the other side
> of the bridge, will see a train that measures 1500 meters, and he is
> convinced that there is three times the place to pass.
> Even better.
> In the train's repository, a passenger is sure to die when they see the
> bridge arriving. But he is sure that he "could not die" after crossing the
> bridge (if at all he crosses it).
> Who is right about these six different observations, made by different
> observers, three of which are of a mortal opinion, and three of a
> confident opinion.
>
> R.H.
>

As I mentioned, this is easily resolved and is easily looked up in
textbooks.

--
Odd Bodkin -- maker of fine toys, tools, tables

Richard Hachel <r.hachel@tiscali.fr> wrote:
> Le 09/12/2021 à 13:18, Sylvia Else a écrit :
>> On 09-Dec-21 10:26 pm, Richard Hachel wrote:
>>> The train paradox.
>>> Everyone knows this paradox.
>>> A train is running on a 0.8c railway line.
>>> The train measures 500 meters at rest.
>>> In the terrestrial frame of reference, it measures only 300 meters.
>>> We will then place a bridge over which he must pass, but this bridge is
>>> not finished. Lack of 500 meters for the connection.
>>> In the train's frame of reference, the train measures 500 meters, and
>>> the hole 300 meters.
>>> By some means, we make sure that either the train will be able to pass,
>>> or it will not be able to.
>>> We imagine that if at least part of the train touches the rail, it will
>>> be kept on the track (gravitational or electric effect, etc.).
>>
>> You can't just claim that the effects are whatever is required to create
>> your 'paradox'.
>>
>> In both frames the train takes on the order of a microsecond to cross
>> the gap. The train will accelerate downwards due to gravity, falling a
>> negligible distance during that time. So in both frames the train will
>> have no difficult making the crossing.
>>
>> Sylvia.
>
> Do you put dust under the carpet when you clean your house?
> This is what most relativistic theorists have been doing with me for
> decades.

I’m not sure I’m following you. First of all, talking here is not talking
with a crowd of “relativistic theorists”. Secondly, this is an example of
basic instructional cases that are covered in introductory textbooks. Why
are you fishing here for explanations instead of just reading those?

> Since they do NOT want to argue with me because I terrify them, they put
> dust under the carpet.
> And when I ask a question, they always do like that.
> It allows them not to show their incompetence.
> At worst, they overwhelm me with insults or contempt.
> But they never answer the questions correctly.
> Never.
> Well almost. Let's be honest, there are people out there who try to do it
> right. But there aren't many.
>
> R.H.
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Richard Hachel <r.hachel@tiscali.fr> wrote:

> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>
> > Try to understand it,
>
> First try to let go of your stinky arrogance.
>
> > Jan
>
> R.H.

Why should I?
I understand it,

Jan

Richard Hachel <r.hachel@tiscali.fr> wrote:

> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>
> > <https://en.wikipedia.org/wiki/Ladder_paradox>
>
> All of this does not answer the question I asked at all.
>
> > Jan
>
> What's happens for the train?

See <https://en.wikipedia.org/wiki/Ladder_paradox>

Jan

Le 09/12/2021 à 15:50, Michael Moroney a écrit :
> On 12/9/2021 7:11 AM, Richard Hachel wrote:
>> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>>
>>> Try to understand it,
>>
>> First try to let go of your stinky arrogance.
>>
> You are the arrogant one around here, you know.You couldn't even post
> the question without implications of SR being 'rotten' and 'absurd'.
> (this is actually mild for you)

Except me, I know you've noticed because you're smart, I go after ideas,
not people. This is far from being the case with other men.

R.H.

Le 09/12/2021 à 16:07, Michael Moroney a écrit :
> The problem with that analysis is that you implicitly assume that there
> is some sort of infinite speed communication of the front and rear of
> the train with each other so that the train can 'decide' to fall into
> the gap if and only if both ends are not supported. Then you point out
> how in one frame both ends are unsupported and in another they never are
> both unsupported. Paradox. However, there is no such infinite speed
> communication. The front of the train can only 'know' about the
> situation of the rear as it was 500/c seconds ago. Same for the bridge,
> one end can only 'know' about the situation of the other end as it was
> 500/c seconds ago. This is much like the bug/rivet 'paradox' which
> isn't a paradox if you remember it takes a finite time for the event of
> the rivet head reaching the wall to reach the tip, so the bug is always
> squashed.

In the example I gave, which three observers are right, and which three
are wrong?

R.H.

Le 09/12/2021 à 16:56, Odd Bodkin a écrit :
> Richard Hachel <r.hachel@tiscali.fr> wrote:
>> Le 09/12/2021 à 13:18, Sylvia Else a écrit :
>>> On 09-Dec-21 10:26 pm, Richard Hachel wrote:
>>>> The train paradox.
>>>> Everyone knows this paradox.
>>>> A train is running on a 0.8c railway line.
>>>> The train measures 500 meters at rest.
>>>> In the terrestrial frame of reference, it measures only 300 meters.
>>>> We will then place a bridge over which he must pass, but this bridge is
>>>> not finished. Lack of 500 meters for the connection.
>>>> In the train's frame of reference, the train measures 500 meters, and
>>>> the hole 300 meters.
>>>> By some means, we make sure that either the train will be able to pass,
>>>> or it will not be able to.
>>>> We imagine that if at least part of the train touches the rail, it will
>>>> be kept on the track (gravitational or electric effect, etc.).
>>>
>>> You can't just claim that the effects are whatever is required to create
>>> your 'paradox'.
>>>
>>> In both frames the train takes on the order of a microsecond to cross
>>> the gap. The train will accelerate downwards due to gravity, falling a
>>> negligible distance during that time. So in both frames the train will
>>> have no difficult making the crossing.
>>>
>>> Sylvia.
>>
>> Do you put dust under the carpet when you clean your house?
>> This is what most relativistic theorists have been doing with me for
>> decades.
>
> I’m not sure I’m following you. First of all, talking here is not talking
> with a crowd of “relativistic theorists”. Secondly, this is an example of
> basic instructional cases that are covered in introductory textbooks. Why
> are you fishing here for explanations instead of just reading those?
>
>> Since they do NOT want to argue with me because I terrify them, they put
>> dust under the carpet.
>> And when I ask a question, they always do like that.
>> It allows them not to show their incompetence.
>> At worst, they overwhelm me with insults or contempt.
>> But they never answer the questions correctly.
>> Never.
>> Well almost. Let's be honest, there are people out there who try to do it
>> right. But there aren't many.
>>
>> R.H.
>>

The problem, as for decades, is that my questions are never answered
correctly.
They either send me personal insults, which I never do, since I attack
ideas, not men, or they send me back to considerations that I already
know, and that precisely, I try to understand before taking them. learn by
heart.
The problem is, the more I try to figure it out, the more I realize that
something is wrong.
I'm not saying ALL of the SR is wrong. I never said that. I say that
things are not right there.

R.H.

Le 09/12/2021 à 20:36, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
> Richard Hachel <r.hachel@tiscali.fr> wrote:
>
>> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>>
>> > <https://en.wikipedia.org/wiki/Ladder_paradox>
>>
>> All of this does not answer the question I asked at all.
>>
>> > Jan
>>
>> What's happens for the train?
>
> See <https://en.wikipedia.org/wiki/Ladder_paradox>
>
> Jan

There is an anomaly and "dust under the carpet" in this example.
It shows an elastic and non-rigid train.
In my example, we are going to attach a huge iron rod to each side of the
train, so that it does not bend as in the wrong answer to the problem.
I ask my question again, what will happen?
I have had the same answers for decades when dealing with the Langevin
Traveler Problem. Most people don't know how to answer, and those who try
put "relativistic dust under the rug" and don't answer.
I recognize, on the other hand, that there are sometimes real intelligent
and courteous people who try to answer me.
I admit that in today's crazy world, that's already a lot, and I admire
them greatly.

R.H.

Richard Hachel <r.hachel@tiscali.fr> wrote:
> Le 09/12/2021 à 16:56, Odd Bodkin a écrit :
>> Richard Hachel <r.hachel@tiscali.fr> wrote:
>>> Le 09/12/2021 à 13:18, Sylvia Else a écrit :
>>>> On 09-Dec-21 10:26 pm, Richard Hachel wrote:
>>>>> The train paradox.
>>>>> Everyone knows this paradox.
>>>>> A train is running on a 0.8c railway line.
>>>>> The train measures 500 meters at rest.
>>>>> In the terrestrial frame of reference, it measures only 300 meters.
>>>>> We will then place a bridge over which he must pass, but this bridge is
>>>>> not finished. Lack of 500 meters for the connection.
>>>>> In the train's frame of reference, the train measures 500 meters, and
>>>>> the hole 300 meters.
>>>>> By some means, we make sure that either the train will be able to pass,
>>>>> or it will not be able to.
>>>>> We imagine that if at least part of the train touches the rail, it will
>>>>> be kept on the track (gravitational or electric effect, etc.).
>>>>
>>>> You can't just claim that the effects are whatever is required to create
>>>> your 'paradox'.
>>>>
>>>> In both frames the train takes on the order of a microsecond to cross
>>>> the gap. The train will accelerate downwards due to gravity, falling a
>>>> negligible distance during that time. So in both frames the train will
>>>> have no difficult making the crossing.
>>>>
>>>> Sylvia.
>>>
>>> Do you put dust under the carpet when you clean your house?
>>> This is what most relativistic theorists have been doing with me for
>>> decades.
>>
>> I’m not sure I’m following you. First of all, talking here is not talking
>> with a crowd of “relativistic theorists”. Secondly, this is an example of
>> basic instructional cases that are covered in introductory textbooks. Why
>> are you fishing here for explanations instead of just reading those?
>>
>>> Since they do NOT want to argue with me because I terrify them, they put
>>> dust under the carpet.
>>> And when I ask a question, they always do like that.
>>> It allows them not to show their incompetence.
>>> At worst, they overwhelm me with insults or contempt.
>>> But they never answer the questions correctly.
>>> Never.
>>> Well almost. Let's be honest, there are people out there who try to do it
>>> right. But there aren't many.
>>>
>>> R.H.
>>>
>
> The problem, as for decades, is that my questions are never answered
> correctly.

Well, it could be that they are in fact answered correctly but that you do
not understand the answers. This doesn’t imply that you are stupid, only
that you are uneducated in relativity. However, if you then insist that the
answer you do not understand must be wrong, then this DOES imply that you
have a mental problem.

> They either send me personal insults, which I never do, since I attack
> ideas, not men, or they send me back to considerations that I already
> know, and that precisely, I try to understand before taking them. learn by
> heart.
> The problem is, the more I try to figure it out, the more I realize that
> something is wrong.

The problem is, you’re trying to figure it out on your own and not reading
a book. Doing it that way is unlikely to produce a sensible result.

> I'm not saying ALL of the SR is wrong. I never said that. I say that
> things are not right there.
>
> R.H.
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Richard Hachel <r.hachel@tiscali.fr> wrote:
> Le 09/12/2021 à 20:36, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>> Richard Hachel <r.hachel@tiscali.fr> wrote:
>>
>>> Le 09/12/2021 à 12:56, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>>>
>>>> <https://en.wikipedia.org/wiki/Ladder_paradox>
>>>
>>> All of this does not answer the question I asked at all.
>>>
>>>> Jan
>>>
>>> What's happens for the train?
>>
>> See <https://en.wikipedia.org/wiki/Ladder_paradox>
>>
>> Jan
>
> There is an anomaly and "dust under the carpet" in this example.
> It shows an elastic and non-rigid train.
> In my example, we are going to attach a huge iron rod to each side of the
> train, so that it does not bend as in the wrong answer to the problem.

No, Richard. There is NO SUCH THING as an arbitrarily rigid rod. Such an
idea violates the laws of physics.

There is a very simple physical explanation why no solid object can be
rigid. Any solid body consists of atoms, and a disturbance at one end has
to transmit through neighboring atoms, in a chain to the atoms at the other
end. This is true whether the “huge rod” is made of iron or diamond,
whether it is an inch in diameter or a meter in diameter. That transmission
happens at the speed of sound in the solid material, no faster.

This means that if you took a GIANT steel rod, four meters in diameter and
a hundred meters long, and you abruptly stopped the front end of the rod,
the back end of that giant steel rod would CONTINUE MOVING for another 17
millisecond before it even received notice that the front end had stopped.
If that giant rod is moving at 100 km per second, the back end of the rod
will move almost 1700 meters before even starting to slow down.

The more rigid the material, the faster the speed of sound. But the speed
of sound cannot be infinite, and in fact can never even be close to c. So
there is no such thing as perfect rigidity.

This is not sweeping dust under the rug. It is simply not allowing a
supposition about perfect rigidity that is counter to the laws of physics.

This, by the way, is an important lesson explicitly taught in books about
relativity, which I gather you have not read. Instead, you have just tried
to figure it out on your own, and in the process you make mistakes.

> I ask my question again, what will happen?
> I have had the same answers for decades when dealing with the Langevin
> Traveler Problem. Most people don't know how to answer, and those who try
> put "relativistic dust under the rug" and don't answer.
> I recognize, on the other hand, that there are sometimes real intelligent
> and courteous people who try to answer me.
> I admit that in today's crazy world, that's already a lot, and I admire
> them greatly.
>
> R.H.
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Le 09/12/2021 à 23:45, Odd Bodkin a écrit :
> No, Richard. There is NO SUCH THING as an arbitrarily rigid rod. Such an
> idea violates the laws of physics.
>
> There is a very simple physical explanation why no solid object can be
> rigid. Any solid body consists of atoms, and a disturbance at one end has
> to transmit through neighboring atoms, in a chain to the atoms at the other
> end. This is true whether the “huge rod” is made of iron or diamond,
> whether it is an inch in diameter or a meter in diameter. That transmission
> happens at the speed of sound in the solid material, no faster.
>
> This means that if you took a GIANT steel rod, four meters in diameter and
> a hundred meters long, and you abruptly stopped the front end of the rod,
> the back end of that giant steel rod would CONTINUE MOVING for another 17
> millisecond before it even received notice that the front end had stopped.
> If that giant rod is moving at 100 km per second, the back end of the rod
> will move almost 1700 meters before even starting to slow down.
>
> The more rigid the material, the faster the speed of sound. But the speed
> of sound cannot be infinite, and in fact can never even be close to c. So
> there is no such thing as perfect rigidity.
>
> This is not sweeping dust under the rug. It is simply not allowing a
> supposition about perfect rigidity that is counter to the laws of physics.
>
> This, by the way, is an important lesson explicitly taught in books about
> relativity, which I gather you have not read. Instead, you have just tried
> to figure it out on your own, and in the process you make mistakes.

I think it is impossible to get along under such conditions.
I think the relativsites, who are facing a very big problem (me), cannot
clearly answer all of my questions.
I just offer thought experiments, and when you can't answer, I'm told
about physical impossibilities, or you drown things in a haze of words.
I think it's manipulation.
Gentle, unconscious manipulation that believes it is necessary for the
good of science.
But handling all the same.
And we never answer clearly and openly to the questions I ask. Precise
questions, often asked with digital applications to make them concrete.
But digital applications that we avoid even more than my questions,
because they require an answer, and that we cannot answer me: "go see on
such site, or listen to such video".
There, you have to answer me, and it's not easy to cheat, or to dust the
carpet. I ask very simple questions, often concrete, with very simple
digital applications.
I ask for example what is the speed of the rocket? I am not being
answered.
I ask if a 300-meter train moving at such a speed will fall into a
300-meter hole, I am next told that "physically, it is not possible".
This is, of course, a thought experiment. I know that there are no trains
today capable of going at such speeds. That's not what I'm talking about.

R.H.