Hi NG

I had recently read a book about GR and found it astonishing, what
Einstein and Ehrenfest said about observers on a rotating disk.

https://en.wikipedia.org/wiki/Ehrenfest_paradox

To me it is selfevident, that observers on a rotating disk would
encounter some kind of outwards acceleration, if that disk rotates.

Also the rigid disk itself would ecounter 'length elongation' (radius
gets longer), because the centrifugal acceleration tends to tear the
disk apart.

But neither of these effects were mentioned, while the similarity to
gravitation assumed.

But as far as I know, gravitation pulls into the opposite direction
(towards the center).

And: the observer could not possibly regard his rotating disk as at
rest, because he had trouble to stay on his feet and on the disk, if
that disk rotates.

TH

Thomas Heger <ttt_heg@web.de> wrote:

> Hi NG
>
> I had recently read a book about GR and found it astonishing, what
> Einstein and Ehrenfest said about observers on a rotating disk.
>
> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>
>
>
> To me it is selfevident, that observers on a rotating disk would
> encounter some kind of outwards acceleration, if that disk rotates.

It was evident then, and it should be evident now,
is that special relativity by itself
is not adequate to deal with the situation.
That's all there is to it,

Jan

Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
> Thomas Heger <ttt_heg@web.de> wrote:
>
>> Hi NG
>>
>> I had recently read a book about GR and found it astonishing, what
>> Einstein and Ehrenfest said about observers on a rotating disk.
>>
>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>>
>>
>>
>> To me it is selfevident, that observers on a rotating disk would
>> encounter some kind of outwards acceleration, if that disk rotates.
>
> It was evident then, and it should be evident now,
> is that special relativity by itself
> is not adequate to deal with the situation.
> That's all there is to it,
>
> Jan

Coward, coward!

R.H.

Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>> Thomas Heger <ttt_heg@web.de> wrote:
>>
>>> Hi NG
>>>
>>> I had recently read a book about GR and found it astonishing, what
>>> Einstein and Ehrenfest said about observers on a rotating disk.
>>>
>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>>>
>>>
>>>
>>> To me it is selfevident, that observers on a rotating disk would
>>> encounter some kind of outwards acceleration, if that disk rotates.
>>
>> It was evident then, and it should be evident now,
>> is that special relativity by itself
>> is not adequate to deal with the situation.
>> That's all there is to it,
>>
>> Jan
>
> Coward, coward!
>
> R.H.

For me, no matter how many times I tossed the problem around for decades,
it always ended up that both the circumference AND the radius contracted.
Let's take for example a point A which passes at the top of the record
at 12 o'clock position.
It has practically zero velocity in "y" at this instant, and its entire
velocity vector is practically in "x".
But we are in a rotating frame of reference, and not in a purely
Galilean frame of reference.
This mini component in y still exists, and it should be noted that this
small Δy does not undergo any obvious contraction, as its speed is low
compared to the tangential speed.
If we decompose the movement, we then understand that the part Δy does
not contract or only slightly, and that the part Δx contracts greatly at
relativistic speed.
The observable residual velocity vector is therefore deviated inwards.
This can explain why the disk ALSO contracts at the level of the radius,
and why there is no paradox, since pi remains invariant in this case.

R.H.

Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> Le 25/12/2023 à 17:26, Richard Hachel a écrit :
>> Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>>> Thomas Heger <ttt_heg@web.de> wrote:
>>>
>>>> Hi NG
>>>>
>>>> I had recently read a book about GR and found it astonishing, what
>>>> Einstein and Ehrenfest said about observers on a rotating disk.
>>>>
>>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>>>>
>>>>
>>>>
>>>> To me it is selfevident, that observers on a rotating disk would
>>>> encounter some kind of outwards acceleration, if that disk rotates.
>>>
>>> It was evident then, and it should be evident now,
>>> is that special relativity by itself
>>> is not adequate to deal with the situation.
>>> That's all there is to it,
>>>
>>> Jan
>>
>> Coward, coward!
>>
>> R.H.
>
> For me, no matter how many times I tossed the problem around for
> decades, it always ended up that both the circumference AND the radius
> contracted.
>
> Let's take for example a point A which passes at the top of the record
> at 12 o'clock position.
>
> It has practically zero velocity in "y" at this instant, and its
> entire velocity vector is practically in "x".
>
> But we are in a rotating frame of reference, and not in a purely
> Galilean frame of reference.

Sure, a rotating frame of reference is not inertial.

The reason: rotation is causing acceleration and that is measurable
without any reference.

So, rotation is 'absolute', while inertial movement is 'relative'.

We know this 'absoluteness' from the realm of missile guidence or
satelite control.

They use laser gyroscopes, which can detect very small rotations.

For rotation you don't need to see a reference point, because rotation
causes acceleration. And acceleration is not inertial.

> This mini component in y still exists, and it should be noted that
> this small Δy does not undergo any obvious contraction, as its speed is
> low compared to the tangential speed.

Sure.

But you certainly don't want to be an observer on a rotating disk, which
has tangential velocity in the relativistic realm.

That would be like sitting on a carussel, which runs insanely fast.

You will be shot from that disk like a cannon ball.

Therefore only very slow rotation is somehow feasable (for human
observers), which is far far far from relativity velocity.

> If we decompose the movement, we then understand that the part Δy does
> not contract or only slightly, and that the part Δx contracts greatly at
> relativistic speed.

If you want to enter the realm of special relativity, you need extremely
high angular velocity or extremely large disks (or both).

This will bring the 'rigid' disk into its critical realm, where tensions
are far greater than the strength of the material could possibly be.

But at least: the radius will not shrink nor will the circumference.

(more likely: that disk will break)

> The observable residual velocity vector is therefore deviated inwards.
>
> This can explain why the disk ALSO contracts at the level of the
> radius, and why there is no paradox, since pi remains invariant in this
> case.

I have absolutely no idea, what Einstein and Ehrenfest actually wanted
to say.

To me this 'paradox' is just nuts.

TH

Am 27.12.2023 um 06:39 schrieb Thomas Heger:
> laser gyroscopes

https://en.wikipedia.org/wiki/Ring_laser_gyroscope

Quote

"Principle of operation
According to the Sagnac effect, rotation induces a small difference
between the time it takes light to traverse the ring in the two
directions. This introduces a tiny separation between the frequencies of
the counter-propagating beams, a motion of the standing wave pattern
within the ring, and thus a beat pattern when those two beams interfere
outside the ring. Therefore, the net shift of that interference pattern
follows the rotation of the unit in the plane of the ring. "

https://en.wikipedia.org/wiki/Sagnac_effect

Quote

"The effect is a consequence of the different times it takes right and
left moving light beams to complete a full round trip in the
interferometer ring. ...
The rotation thus measured is an absolute rotation, that is, the
platform's rotation with respect to an inertial reference frame. "

Rotation is therefore 'absolute', while inertial motion isn't.

TH

Le 28/12/2023 à 09:01, Thomas Heger a écrit :

> Rotation is therefore 'absolute', while inertial motion isn't.

There is a difference between a non-rotating disk moving Galileanly at
Vo=0.8c from right to left, and a fixed disk rotating with a tangential
speed of 0.8c.

These are therefore not, obviously, the same equations that must be used.
For the disk in translation, it's easy, the Poincaré-Lorentz
transformations are enough. For the rotating disk, the reflection becomes
appalling, and a lot of people have thrown in the towel in the face of the
simple Ehrenfest paradox.

R.H.

On Sunday, December 24, 2023 at 4:18:36 AM UTC-8, J. J. Lodder wrote:
> Thomas Heger <ttt...@web.de> wrote:
>
> > Hi NG
> >
> > I had recently read a book about GR and found it astonishing, what
> > Einstein and Ehrenfest said about observers on a rotating disk.
> >
> > https://en.wikipedia.org/wiki/Ehrenfest_paradox
> >
> >
> >
> > To me it is selfevident, that observers on a rotating disk would
> > encounter some kind of outwards acceleration, if that disk rotates.
> It was evident then, and it should be evident now,
> is that special relativity by itself
> is not adequate to deal with the situation.
> That's all there is to it,
>
> Jan

Special Relativity's always with General Relativity,
and always after or never before.

.... and Quantum Mechanics, with Gravity in the middle,
a quantum gravity, according to principled teleology,
a fall gravity.

Ehrenfest disc makes a cool effect called "space-time wheel".

I.e., two counter-rotating discs draw c down, in a sense.

It's space contraction, it's a continuum mechanics.

Of course it would help to have a mathematics with at
least three mutually consistent definitions of continuity, ....

....

Thomas Heger <ttt_heg@web.de> wrote:

> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> >> Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
> >>> Thomas Heger <ttt_heg@web.de> wrote:
> >>>
> >>>> Hi NG
> >>>>
> >>>> I had recently read a book about GR and found it astonishing, what
> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> >>>>
> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> >>>>
> >>>>
> >>>>
> >>>> To me it is selfevident, that observers on a rotating disk would
> >>>> encounter some kind of outwards acceleration, if that disk rotates.
> >>>
> >>> It was evident then, and it should be evident now,
> >>> is that special relativity by itself
> >>> is not adequate to deal with the situation.
> >>> That's all there is to it,
> >>>
> >>> Jan
> >>
> >> Coward, coward!
> >>
> >> R.H.
> >
> > For me, no matter how many times I tossed the problem around for
> > decades, it always ended up that both the circumference AND the radius
> > contracted.
> >
> > Let's take for example a point A which passes at the top of the record
> > at 12 o'clock position.
> >
> > It has practically zero velocity in "y" at this instant, and its
> > entire velocity vector is practically in "x".
> >
> > But we are in a rotating frame of reference, and not in a purely
> > Galilean frame of reference.
>
>
> Sure, a rotating frame of reference is not inertial.
>
> The reason: rotation is causing acceleration and that is measurable
> without any reference.
>
> So, rotation is 'absolute', while inertial movement is 'relative'.
>
> We know this 'absoluteness' from the realm of missile guidence or
> satelite control.
>
> They use laser gyroscopes, which can detect very small rotations.
>
> For rotation you don't need to see a reference point, because rotation
> causes acceleration. And acceleration is not inertial.
>
> > This mini component in y still exists, and it should be noted that
> > this small ?y does not undergo any obvious contraction, as its speed is
> > low compared to the tangential speed.
>
> Sure.
>
> But you certainly don't want to be an observer on a rotating disk, which
> has tangential velocity in the relativistic realm.
>
> That would be like sitting on a carussel, which runs insanely fast.
>
> You will be shot from that disk like a cannon ball.
>
> Therefore only very slow rotation is somehow feasable (for human
> observers), which is far far far from relativity velocity.
>
>
> > If we decompose the movement, we then understand that the part ?y does
> > not contract or only slightly, and that the part ?x contracts greatly at
> > relativistic speed.
>
> If you want to enter the realm of special relativity, you need extremely
> high angular velocity or extremely large disks (or both).
>
> This will bring the 'rigid' disk into its critical realm, where tensions
> are far greater than the strength of the material could possibly be.
>
> But at least: the radius will not shrink nor will the circumference.
>
> (more likely: that disk will break)
>
>
> > The observable residual velocity vector is therefore deviated inwards.
> >
> > This can explain why the disk ALSO contracts at the level of the
> > radius, and why there is no paradox, since pi remains invariant in this
> > case.
>
> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> to say.

Einstein and Ehrenfest just took the 'paradox' as heuristics.
It makes it obvious that you can not deal with the situation
in simple-minded and ad-hoc ways.
(not even with extreme idealisations)

To Einstein it pointed the way to the need for non-Euclidean geometry.

Jan

On Thursday 28 December 2023 at 13:18:04 UTC+1, J. J. Lodder wrote:
> Thomas Heger <ttt...@web.de> wrote:
>
> > Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > >>> Thomas Heger <ttt...@web.de> wrote:
> > >>>
> > >>>> Hi NG
> > >>>>
> > >>>> I had recently read a book about GR and found it astonishing, what
> > >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > >>>>
> > >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > >>>>
> > >>>>
> > >>>>
> > >>>> To me it is selfevident, that observers on a rotating disk would
> > >>>> encounter some kind of outwards acceleration, if that disk rotates..
> > >>>
> > >>> It was evident then, and it should be evident now,
> > >>> is that special relativity by itself
> > >>> is not adequate to deal with the situation.
> > >>> That's all there is to it,
> > >>>
> > >>> Jan
> > >>
> > >> Coward, coward!
> > >>
> > >> R.H.
> > >
> > > For me, no matter how many times I tossed the problem around for
> > > decades, it always ended up that both the circumference AND the radius
> > > contracted.
> > >
> > > Let's take for example a point A which passes at the top of the record
> > > at 12 o'clock position.
> > >
> > > It has practically zero velocity in "y" at this instant, and its
> > > entire velocity vector is practically in "x".
> > >
> > > But we are in a rotating frame of reference, and not in a purely
> > > Galilean frame of reference.
> >
> >
> > Sure, a rotating frame of reference is not inertial.
> >
> > The reason: rotation is causing acceleration and that is measurable
> > without any reference.
> >
> > So, rotation is 'absolute', while inertial movement is 'relative'.
> >
> > We know this 'absoluteness' from the realm of missile guidence or
> > satelite control.
> >
> > They use laser gyroscopes, which can detect very small rotations.
> >
> > For rotation you don't need to see a reference point, because rotation
> > causes acceleration. And acceleration is not inertial.
> >
> > > This mini component in y still exists, and it should be noted that
> > > this small ?y does not undergo any obvious contraction, as its speed is
> > > low compared to the tangential speed.
> >
> > Sure.
> >
> > But you certainly don't want to be an observer on a rotating disk, which
> > has tangential velocity in the relativistic realm.
> >
> > That would be like sitting on a carussel, which runs insanely fast.
> >
> > You will be shot from that disk like a cannon ball.
> >
> > Therefore only very slow rotation is somehow feasable (for human
> > observers), which is far far far from relativity velocity.
> >
> >
> > > If we decompose the movement, we then understand that the part ?y does
> > > not contract or only slightly, and that the part ?x contracts greatly at
> > > relativistic speed.
> >
> > If you want to enter the realm of special relativity, you need extremely
> > high angular velocity or extremely large disks (or both).
> >
> > This will bring the 'rigid' disk into its critical realm, where tensions
> > are far greater than the strength of the material could possibly be.
> >
> > But at least: the radius will not shrink nor will the circumference.
> >
> > (more likely: that disk will break)
> >
> >
> > > The observable residual velocity vector is therefore deviated inwards..
> > >
> > > This can explain why the disk ALSO contracts at the level of the
> > > radius, and why there is no paradox, since pi remains invariant in this
> > > case.
> >
> > I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > to say.
> Einstein and Ehrenfest just took the 'paradox' as heuristics.
> It makes it obvious that you can not deal with the situation
> in simple-minded and ad-hoc ways.
> (not even with extreme idealisations)
>
> To Einstein it pointed the way to the need for non-Euclidean geometry.

As basic mathematics didn't want to support his madness
- the idiot had to reject it and create another, more obedient.

Le 28/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
> Thomas Heger <ttt_heg@web.de> wrote:
>
>> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
>> > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
>> >> Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>> >>> Thomas Heger <ttt_heg@web.de> wrote:
>> >>>
>> >>>> Hi NG
>> >>>>
>> >>>> I had recently read a book about GR and found it astonishing, what
>> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
>> >>>>
>> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>> >>>>
>> >>>>
>> >>>>
>> >>>> To me it is selfevident, that observers on a rotating disk would
>> >>>> encounter some kind of outwards acceleration, if that disk rotates.
>> >>>
>> >>> It was evident then, and it should be evident now,
>> >>> is that special relativity by itself
>> >>> is not adequate to deal with the situation.
>> >>> That's all there is to it,
>> >>>
>> >>> Jan
>> >>
>> >> Coward, coward!
>> >>
>> >> R.H.
>> >
>> > For me, no matter how many times I tossed the problem around for
>> > decades, it always ended up that both the circumference AND the radius
>> > contracted.
>> >
>> > Let's take for example a point A which passes at the top of the record
>> > at 12 o'clock position.
>> >
>> > It has practically zero velocity in "y" at this instant, and its
>> > entire velocity vector is practically in "x".
>> >
>> > But we are in a rotating frame of reference, and not in a purely
>> > Galilean frame of reference.
>>
>>
>> Sure, a rotating frame of reference is not inertial.
>>
>> The reason: rotation is causing acceleration and that is measurable
>> without any reference.
>>
>> So, rotation is 'absolute', while inertial movement is 'relative'.
>>
>> We know this 'absoluteness' from the realm of missile guidence or
>> satelite control.
>>
>> They use laser gyroscopes, which can detect very small rotations.
>>
>> For rotation you don't need to see a reference point, because rotation
>> causes acceleration. And acceleration is not inertial.
>>
>> > This mini component in y still exists, and it should be noted that
>> > this small ?y does not undergo any obvious contraction, as its speed is
>> > low compared to the tangential speed.
>>
>> Sure.
>>
>> But you certainly don't want to be an observer on a rotating disk, which
>> has tangential velocity in the relativistic realm.
>>
>> That would be like sitting on a carussel, which runs insanely fast.
>>
>> You will be shot from that disk like a cannon ball.
>>
>> Therefore only very slow rotation is somehow feasable (for human
>> observers), which is far far far from relativity velocity.
>>
>>
>> > If we decompose the movement, we then understand that the part ?y does
>> > not contract or only slightly, and that the part ?x contracts greatly at
>> > relativistic speed.
>>
>> If you want to enter the realm of special relativity, you need extremely
>> high angular velocity or extremely large disks (or both).
>>
>> This will bring the 'rigid' disk into its critical realm, where tensions
>> are far greater than the strength of the material could possibly be.
>>
>> But at least: the radius will not shrink nor will the circumference.
>>
>> (more likely: that disk will break)
>>
>>
>> > The observable residual velocity vector is therefore deviated inwards.
>> >
>> > This can explain why the disk ALSO contracts at the level of the
>> > radius, and why there is no paradox, since pi remains invariant in this
>> > case.
>>
>> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
>> to say.
>
> Einstein and Ehrenfest just took the 'paradox' as heuristics.
> It makes it obvious that you can not deal with the situation
> in simple-minded and ad-hoc ways.
> (not even with extreme idealisations)
>
> To Einstein it pointed the way to the need for non-Euclidean geometry.
>
> Jan

When physicists don't know how to answer, they say "It's not Euclidean
geometry." But they don't know how to clearly explain what it is.
If we talk to them about the Ehrenfest paradox, they don't know how to
answer.
If we ask them who Doctor Hachel is, they say "We don't know this
gentleman."
If we talk to them about universal anisochrony, and the relativity of
chronotropy, they hold their noses.
If we clearly explain to them how we solve the Langevin paradox, they
scream like pigs being slaughtered.
If we talk to them about the spatial zoom effect, they have an epileptic
seizure.

All this is not very serious.

Relativist theorists are the shame of science just as Pauline Christians
and fundamentalist Muslims are the shame of religion.

R.H.

Le 28/12/2023 à 15:19, Richard Hachel a écrit :
> Le 28/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a écrit :
>> Thomas Heger <ttt_heg@web.de> wrote:
>>
>>> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
>>> > Le 25/12/2023 à 17:26, Richard Hachel  a écrit :
>>> >> Le 24/12/2023 à 13:18, nospam@de-ster.demon.nl (J. J. Lodder) a
>>> écrit :
>>> >>> Thomas Heger <ttt_heg@web.de> wrote:
>>> >>>
>>> >>>> Hi NG
>>> >>>>
>>> >>>> I had recently read a book about GR and found it astonishing, what
>>> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
>>> >>>>
>>> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>>> To me it is selfevident, that observers on a rotating disk would
>>> >>>> encounter some kind of outwards acceleration, if that disk rotates.
>>> >>>
>>> >>> It was evident then, and it should be evident now,
>>> >>> is that special relativity by itself
>>> >>> is not adequate to deal with the situation.
>>> >>> That's all there is to it,
>>> >>>
>>> >>> Jan
>>> >>
>>> >> Coward, coward!
>>> >>
>>> >> R.H.
>>> >
>>> > For me, no matter how many times I tossed the problem around for
>>> > decades, it always ended up that both the circumference AND the radius
>>> > contracted.
>>> >
>>> >   Let's take for example a point A which passes at the top of the
>>> record
>>> > at 12 o'clock position.
>>> >
>>> >   It has practically zero velocity in "y" at this instant, and its
>>> > entire velocity vector is practically in "x".
>>> >
>>> >   But we are in a rotating frame of reference, and not in a purely
>>> > Galilean frame of reference.
>>>
>>>
>>> Sure, a rotating frame of reference is not inertial.
>>>
>>> The reason: rotation is causing acceleration and that is measurable
>>> without any reference.
>>>
>>> So, rotation is 'absolute', while inertial movement is 'relative'.
>>>
>>> We know this 'absoluteness' from the realm of missile guidence or
>>> satelite control.
>>>
>>> They use laser gyroscopes, which can detect very small rotations.
>>>
>>> For rotation you don't need to see a reference point, because rotation
>>> causes acceleration. And acceleration is not inertial.
>>>
>>> >   This mini component in y still exists, and it should be noted that
>>> > this small ?y does not undergo any obvious contraction, as its
>>> speed is
>>> > low compared to the tangential speed.
>>>
>>> Sure.
>>>
>>> But you certainly don't want to be an observer on a rotating disk, which
>>> has tangential velocity in the relativistic realm.
>>>
>>> That would be like sitting on a carussel, which runs insanely fast.
>>>
>>> You will be shot from that disk like a cannon ball.
>>>
>>> Therefore only very slow rotation is somehow feasable (for human
>>> observers), which is far far far from relativity velocity.
>>>
>>>
>>> >   If we decompose the movement, we then understand that the part ?y
>>> does
>>> > not contract or only slightly, and that the part ?x contracts
>>> greatly at
>>> > relativistic speed.
>>>
>>> If you want to enter the realm of special relativity, you need extremely
>>> high angular velocity or extremely large disks (or both).
>>>
>>> This will bring the 'rigid' disk into its critical realm, where tensions
>>> are far greater than the strength of the material could possibly be.
>>>
>>> But at least: the radius will not shrink nor will the circumference.
>>>
>>> (more likely: that disk will break)
>>>
>>>
>>> >   The observable residual velocity vector is therefore deviated
>>> inwards.
>>> >
>>> >   This can explain why the disk ALSO contracts at the level of the
>>> > radius, and why there is no paradox, since pi remains invariant in
>>> this
>>> > case.
>>>
>>> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
>>> to say.
>>
>> Einstein and Ehrenfest just took the 'paradox' as heuristics.
>> It makes it obvious that you can not deal with the situation
>> in simple-minded and ad-hoc ways.
>> (not even with extreme idealisations)
>>
>> To Einstein it pointed the way to the need for non-Euclidean geometry.
>>
>> Jan
>
> When physicists don't know how to answer, they say "It's not Euclidean
> geometry." But they don't know how to clearly explain what it is.
> If we talk to them about the Ehrenfest paradox, they don't know how to
> answer.
> If we ask them who Doctor Hachel is, they say "We don't know this
> gentleman."
> If we talk to them about universal anisochrony, and the relativity of
> chronotropy, they hold their noses.
> If we clearly explain to them how we solve the Langevin paradox, they
> scream like pigs being slaughtered.
> If we talk to them about the spatial zoom effect, they have an epileptic
> seizure.
>
> All this is not very serious.
>
> Relativist theorists are the shame of science just as Pauline Christians
> and fundamentalist Muslims are the shame of religion.
>
> R.H.

https://gitlab.com/python_431/cranks-and-physics/-/blob/main/Hachel/divagation_lengrand.pdf

Le 28/12/2023 à 16:10, Python a écrit :
> Le 28/12/2023 à 15:19, Richard Hachel a écrit :

Chouette, revoilà Python.

On va encore pouvoir rigoler deux minutes.

Dis-moi, dis-moi, au lieu de faire tes attaques ad hominem à la con,
qu'est ce que tu penses, toi, du paradoxe d'Ehrenfest?

Tes deux neurones fonctionnent encore pour tenter une explication
personnelle?

R.H.

On Thursday, December 28, 2023 at 4:18:04 AM UTC-8, J. J. Lodder wrote:
> Thomas Heger <ttt...@web.de> wrote:
>
> > Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > >>> Thomas Heger <ttt...@web.de> wrote:
> > >>>
> > >>>> Hi NG
> > >>>>
> > >>>> I had recently read a book about GR and found it astonishing, what
> > >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > >>>>
> > >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > >>>>
> > >>>>
> > >>>>
> > >>>> To me it is selfevident, that observers on a rotating disk would
> > >>>> encounter some kind of outwards acceleration, if that disk rotates..
> > >>>
> > >>> It was evident then, and it should be evident now,
> > >>> is that special relativity by itself
> > >>> is not adequate to deal with the situation.
> > >>> That's all there is to it,
> > >>>
> > >>> Jan
> > >>
> > >> Coward, coward!
> > >>
> > >> R.H.
> > >
> > > For me, no matter how many times I tossed the problem around for
> > > decades, it always ended up that both the circumference AND the radius
> > > contracted.
> > >
> > > Let's take for example a point A which passes at the top of the record
> > > at 12 o'clock position.
> > >
> > > It has practically zero velocity in "y" at this instant, and its
> > > entire velocity vector is practically in "x".
> > >
> > > But we are in a rotating frame of reference, and not in a purely
> > > Galilean frame of reference.
> >
> >
> > Sure, a rotating frame of reference is not inertial.
> >
> > The reason: rotation is causing acceleration and that is measurable
> > without any reference.
> >
> > So, rotation is 'absolute', while inertial movement is 'relative'.
> >
> > We know this 'absoluteness' from the realm of missile guidence or
> > satelite control.
> >
> > They use laser gyroscopes, which can detect very small rotations.
> >
> > For rotation you don't need to see a reference point, because rotation
> > causes acceleration. And acceleration is not inertial.
> >
> > > This mini component in y still exists, and it should be noted that
> > > this small ?y does not undergo any obvious contraction, as its speed is
> > > low compared to the tangential speed.
> >
> > Sure.
> >
> > But you certainly don't want to be an observer on a rotating disk, which
> > has tangential velocity in the relativistic realm.
> >
> > That would be like sitting on a carussel, which runs insanely fast.
> >
> > You will be shot from that disk like a cannon ball.
> >
> > Therefore only very slow rotation is somehow feasable (for human
> > observers), which is far far far from relativity velocity.
> >
> >
> > > If we decompose the movement, we then understand that the part ?y does
> > > not contract or only slightly, and that the part ?x contracts greatly at
> > > relativistic speed.
> >
> > If you want to enter the realm of special relativity, you need extremely
> > high angular velocity or extremely large disks (or both).
> >
> > This will bring the 'rigid' disk into its critical realm, where tensions
> > are far greater than the strength of the material could possibly be.
> >
> > But at least: the radius will not shrink nor will the circumference.
> >
> > (more likely: that disk will break)
> >
> >
> > > The observable residual velocity vector is therefore deviated inwards..
> > >
> > > This can explain why the disk ALSO contracts at the level of the
> > > radius, and why there is no paradox, since pi remains invariant in this
> > > case.
> >
> > I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > to say.
> Einstein and Ehrenfest just took the 'paradox' as heuristics.
> It makes it obvious that you can not deal with the situation
> in simple-minded and ad-hoc ways.
> (not even with extreme idealisations)
>
> To Einstein it pointed the way to the need for non-Euclidean geometry.
>
> Jan

What Einstein points to is his "bridge", that most relate to Einstein-Podolsky-Rosen,
but which really is about the interface the linear and rotational, also classical.

That is, Einstein's bridge is about his theory's applications to kinetics and kinematics,
deeply.

The "non-Euclidean" is just transforms reflecting either side
coordinate settings, of what are wells in the well model,
the metrics, a metric, in our gauge theory, a gauge, the R-gauge.

The real gauge, ....

(Though spelled "gauge" it's pronounced "gage" not "gouge".)

....

On Thursday 28 December 2023 at 19:14:13 UTC+1, Ross Finlayson wrote:
> On Thursday, December 28, 2023 at 4:18:04 AM UTC-8, J. J. Lodder wrote:
> > Thomas Heger <ttt...@web.de> wrote:
> >
> > > Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > > > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > > >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > > >>> Thomas Heger <ttt...@web.de> wrote:
> > > >>>
> > > >>>> Hi NG
> > > >>>>
> > > >>>> I had recently read a book about GR and found it astonishing, what
> > > >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > > >>>>
> > > >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>> To me it is selfevident, that observers on a rotating disk would
> > > >>>> encounter some kind of outwards acceleration, if that disk rotates.
> > > >>>
> > > >>> It was evident then, and it should be evident now,
> > > >>> is that special relativity by itself
> > > >>> is not adequate to deal with the situation.
> > > >>> That's all there is to it,
> > > >>>
> > > >>> Jan
> > > >>
> > > >> Coward, coward!
> > > >>
> > > >> R.H.
> > > >
> > > > For me, no matter how many times I tossed the problem around for
> > > > decades, it always ended up that both the circumference AND the radius
> > > > contracted.
> > > >
> > > > Let's take for example a point A which passes at the top of the record
> > > > at 12 o'clock position.
> > > >
> > > > It has practically zero velocity in "y" at this instant, and its
> > > > entire velocity vector is practically in "x".
> > > >
> > > > But we are in a rotating frame of reference, and not in a purely
> > > > Galilean frame of reference.
> > >
> > >
> > > Sure, a rotating frame of reference is not inertial.
> > >
> > > The reason: rotation is causing acceleration and that is measurable
> > > without any reference.
> > >
> > > So, rotation is 'absolute', while inertial movement is 'relative'.
> > >
> > > We know this 'absoluteness' from the realm of missile guidence or
> > > satelite control.
> > >
> > > They use laser gyroscopes, which can detect very small rotations.
> > >
> > > For rotation you don't need to see a reference point, because rotation
> > > causes acceleration. And acceleration is not inertial.
> > >
> > > > This mini component in y still exists, and it should be noted that
> > > > this small ?y does not undergo any obvious contraction, as its speed is
> > > > low compared to the tangential speed.
> > >
> > > Sure.
> > >
> > > But you certainly don't want to be an observer on a rotating disk, which
> > > has tangential velocity in the relativistic realm.
> > >
> > > That would be like sitting on a carussel, which runs insanely fast.
> > >
> > > You will be shot from that disk like a cannon ball.
> > >
> > > Therefore only very slow rotation is somehow feasable (for human
> > > observers), which is far far far from relativity velocity.
> > >
> > >
> > > > If we decompose the movement, we then understand that the part ?y does
> > > > not contract or only slightly, and that the part ?x contracts greatly at
> > > > relativistic speed.
> > >
> > > If you want to enter the realm of special relativity, you need extremely
> > > high angular velocity or extremely large disks (or both).
> > >
> > > This will bring the 'rigid' disk into its critical realm, where tensions
> > > are far greater than the strength of the material could possibly be.
> > >
> > > But at least: the radius will not shrink nor will the circumference.
> > >
> > > (more likely: that disk will break)
> > >
> > >
> > > > The observable residual velocity vector is therefore deviated inwards.
> > > >
> > > > This can explain why the disk ALSO contracts at the level of the
> > > > radius, and why there is no paradox, since pi remains invariant in this
> > > > case.
> > >
> > > I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > > to say.
> > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > It makes it obvious that you can not deal with the situation
> > in simple-minded and ad-hoc ways.
> > (not even with extreme idealisations)
> >
> > To Einstein it pointed the way to the need for non-Euclidean geometry.
> >
> > Jan
> What Einstein points to is his "bridge", that most relate to Einstein-Podolsky-Rosen,
> but which really is about the interface the linear and rotational, also classical.
>
> That is, Einstein's bridge is about his theory's applications to kinetics and kinematics,
> deeply.
>
> The "non-Euclidean" is just transforms reflecting either side
> coordinate settings, of what are wells in the well model,
> the metrics, a metric, in our gauge theory, a gauge, the R-gauge.
>
> The real gauge, ....
>
> (Though spelled "gauge" it's pronounced "gage" not "gouge".)

As basic mathematics didn't want to support his madness
- the idiot had to reject it and create another, more obedient.

On Thursday, December 28, 2023 at 11:04:49 AM UTC-8, Maciej Wozniak wrote:
> On Thursday 28 December 2023 at 19:14:13 UTC+1, Ross Finlayson wrote:
> > On Thursday, December 28, 2023 at 4:18:04 AM UTC-8, J. J. Lodder wrote:
> > > Thomas Heger <ttt...@web.de> wrote:
> > >
> > > > Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > > > > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > > > >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > > > >>> Thomas Heger <ttt...@web.de> wrote:
> > > > >>>
> > > > >>>> Hi NG
> > > > >>>>
> > > > >>>> I had recently read a book about GR and found it astonishing, what
> > > > >>>> Einstein and Ehrenfest said about observers on a rotating disk..
> > > > >>>>
> > > > >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > > > >>>>
> > > > >>>>
> > > > >>>>
> > > > >>>> To me it is selfevident, that observers on a rotating disk would
> > > > >>>> encounter some kind of outwards acceleration, if that disk rotates.
> > > > >>>
> > > > >>> It was evident then, and it should be evident now,
> > > > >>> is that special relativity by itself
> > > > >>> is not adequate to deal with the situation.
> > > > >>> That's all there is to it,
> > > > >>>
> > > > >>> Jan
> > > > >>
> > > > >> Coward, coward!
> > > > >>
> > > > >> R.H.
> > > > >
> > > > > For me, no matter how many times I tossed the problem around for
> > > > > decades, it always ended up that both the circumference AND the radius
> > > > > contracted.
> > > > >
> > > > > Let's take for example a point A which passes at the top of the record
> > > > > at 12 o'clock position.
> > > > >
> > > > > It has practically zero velocity in "y" at this instant, and its
> > > > > entire velocity vector is practically in "x".
> > > > >
> > > > > But we are in a rotating frame of reference, and not in a purely
> > > > > Galilean frame of reference.
> > > >
> > > >
> > > > Sure, a rotating frame of reference is not inertial.
> > > >
> > > > The reason: rotation is causing acceleration and that is measurable
> > > > without any reference.
> > > >
> > > > So, rotation is 'absolute', while inertial movement is 'relative'.
> > > >
> > > > We know this 'absoluteness' from the realm of missile guidence or
> > > > satelite control.
> > > >
> > > > They use laser gyroscopes, which can detect very small rotations.
> > > >
> > > > For rotation you don't need to see a reference point, because rotation
> > > > causes acceleration. And acceleration is not inertial.
> > > >
> > > > > This mini component in y still exists, and it should be noted that
> > > > > this small ?y does not undergo any obvious contraction, as its speed is
> > > > > low compared to the tangential speed.
> > > >
> > > > Sure.
> > > >
> > > > But you certainly don't want to be an observer on a rotating disk, which
> > > > has tangential velocity in the relativistic realm.
> > > >
> > > > That would be like sitting on a carussel, which runs insanely fast.
> > > >
> > > > You will be shot from that disk like a cannon ball.
> > > >
> > > > Therefore only very slow rotation is somehow feasable (for human
> > > > observers), which is far far far from relativity velocity.
> > > >
> > > >
> > > > > If we decompose the movement, we then understand that the part ?y does
> > > > > not contract or only slightly, and that the part ?x contracts greatly at
> > > > > relativistic speed.
> > > >
> > > > If you want to enter the realm of special relativity, you need extremely
> > > > high angular velocity or extremely large disks (or both).
> > > >
> > > > This will bring the 'rigid' disk into its critical realm, where tensions
> > > > are far greater than the strength of the material could possibly be..
> > > >
> > > > But at least: the radius will not shrink nor will the circumference..
> > > >
> > > > (more likely: that disk will break)
> > > >
> > > >
> > > > > The observable residual velocity vector is therefore deviated inwards.
> > > > >
> > > > > This can explain why the disk ALSO contracts at the level of the
> > > > > radius, and why there is no paradox, since pi remains invariant in this
> > > > > case.
> > > >
> > > > I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > > > to say.
> > > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > > It makes it obvious that you can not deal with the situation
> > > in simple-minded and ad-hoc ways.
> > > (not even with extreme idealisations)
> > >
> > > To Einstein it pointed the way to the need for non-Euclidean geometry..
> > >
> > > Jan
> > What Einstein points to is his "bridge", that most relate to Einstein-Podolsky-Rosen,
> > but which really is about the interface the linear and rotational, also classical.
> >
> > That is, Einstein's bridge is about his theory's applications to kinetics and kinematics,
> > deeply.
> >
> > The "non-Euclidean" is just transforms reflecting either side
> > coordinate settings, of what are wells in the well model,
> > the metrics, a metric, in our gauge theory, a gauge, the R-gauge.
> >
> > The real gauge, ....
> >
> > (Though spelled "gauge" it's pronounced "gage" not "gouge".)
> As basic mathematics didn't want to support his madness
> - the idiot had to reject it and create another, more obedient.

Privat, kak dela.

....

Op 24/12/2023 om 9:17 schreef Thomas Heger:
>
> Hi NG
>
> I had recently read a book about GR and found it astonishing, what
> Einstein and Ehrenfest said about observers on a rotating disk.
>
> https://en.wikipedia.org/wiki/Ehrenfest_paradox
>
>
>
> To me it is selfevident, that observers on a rotating disk would
> encounter some kind of outwards acceleration, if that disk rotates.
>
> Also the rigid disk itself would ecounter 'length elongation' (radius
> gets longer), because the centrifugal acceleration tends to tear the
> disk apart.

One can theorize on a material that doesn't elongate or shrink.
Something must be assumed anyway. *

> But neither of these effects were mentioned, while the similarity to
> gravitation assumed.
>
> But as far as I know, gravitation pulls into the opposite direction
> (towards the center).

Similarity to gravitation as a 'geometric' effect in GRT, I'd
understand. It doesn't matter that different settings may produce
opposite effects.

> And: the observer could not possibly regard his rotating disk as at
> rest, because he had trouble to stay on his feet and on the disk, if
> that disk rotates.

I think the EP hasn't got its final conclusions yet.
I feel that two different cases are mixed up in most descriptions.

One, you have this large physical disk in relativistic rotation, in what
for the rest could be simple SRT flat spacetime.
Second, you'd have a curved GRT spacetime behaving as if it were a large
rotating disk.

And many EP "explainers" would seem to try explaining the behaviour of
subparts of "disk 1" by studying the behaviour of small objects in "disk
space 2".
But certainly for disk 1, it is being observed by external flat-space
observers on the one hand, and what happens in/to the disk itself cannot
be described by the sole GRT equations, you'll need _constitutive
equations_ describing the behaviour of the disk material! Like at *
hereabove.
Whereas, studying disk space 2 could be done straight away in a GRT
framework I guess, but it's another problem altogether.

Simpler cases than a solid disk can be studied by "loosening" the disk
into a series of independent rings, even by giving those a cone shape.
That's what I've tried to study in my video here:
https://www.youtube.com/watch?v=AflRNMIMLpU

--
guido wugi

On Sunday, December 24, 2023 at 4:18:36 AM UTC-8, J. J. Lodder wrote:
> Thomas Heger <ttt...@web.de> wrote:
>
> > Hi NG
> >
> > I had recently read a book about GR and found it astonishing, what
> > Einstein and Ehrenfest said about observers on a rotating disk.
> >
> > https://en.wikipedia.org/wiki/Ehrenfest_paradox
> >
> >
> >
> > To me it is selfevident, that observers on a rotating disk would
> > encounter some kind of outwards acceleration, if that disk rotates.
> It was evident then, and it should be evident now,
> is that special relativity by itself
> is not adequate to deal with the situation.
> That's all there is to it,

The original question was about the centrifugal
forces experienced by the observers on the disc. The assumption of the
thought experiment described in Wikipedia is those forces do not affect
the disc or the observers. It's just an idealisation, like assuming friction
doesn't exist, etc.

As for the observers' experience of the disc, it actually describes
not "the" disc but of a certain quotient space (in the
topological sense), namely the spacetime R^3,1 divided by the worldlines
of the disc's material points(*). It's the standard confusion (and the root
cause of the paradox) to assume that that quotient space can be
equipped with a "sensible" time coordinate and the result embedded isometrically in R^3,1.
The discontinuity of the time coordinate introduced by slowly moving
clocks is known as the Sagnac effect and is another can of worms (see
decades of discussions on this NG).

(*)imagine a surface made of infinitesimal spacelike patches Lorentz-
-orthogonal to the worldlines passing through them. If one uses the
differential-geometric ideas to figure out its geometry, it'll turn out
to be negatively curved.

--
Jan

On Thursday, December 28, 2023 at 6:19:48 AM UTC-8, Richard Hachel wrote:
> Le 28/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > Thomas Heger <ttt...@web.de> wrote:
> >
> >> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> >> > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> >> >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> >> >>> Thomas Heger <ttt...@web.de> wrote:
> >> >>>
> >> >>>> Hi NG
> >> >>>>
> >> >>>> I had recently read a book about GR and found it astonishing, what
> >> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> >> >>>>
> >> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> >> >>>>
> >> >>>>
> >> >>>>
> >> >>>> To me it is selfevident, that observers on a rotating disk would
> >> >>>> encounter some kind of outwards acceleration, if that disk rotates.
> >> >>>
> >> >>> It was evident then, and it should be evident now,
> >> >>> is that special relativity by itself
> >> >>> is not adequate to deal with the situation.
> >> >>> That's all there is to it,
> >> >>>
> >> >>> Jan
> >> >>
> >> >> Coward, coward!
> >> >>
> >> >> R.H.
> >> >
> >> > For me, no matter how many times I tossed the problem around for
> >> > decades, it always ended up that both the circumference AND the radius
> >> > contracted.
> >> >
> >> > Let's take for example a point A which passes at the top of the record
> >> > at 12 o'clock position.
> >> >
> >> > It has practically zero velocity in "y" at this instant, and its
> >> > entire velocity vector is practically in "x".
> >> >
> >> > But we are in a rotating frame of reference, and not in a purely
> >> > Galilean frame of reference.
> >>
> >>
> >> Sure, a rotating frame of reference is not inertial.
> >>
> >> The reason: rotation is causing acceleration and that is measurable
> >> without any reference.
> >>
> >> So, rotation is 'absolute', while inertial movement is 'relative'.
> >>
> >> We know this 'absoluteness' from the realm of missile guidence or
> >> satelite control.
> >>
> >> They use laser gyroscopes, which can detect very small rotations.
> >>
> >> For rotation you don't need to see a reference point, because rotation
> >> causes acceleration. And acceleration is not inertial.
> >>
> >> > This mini component in y still exists, and it should be noted that
> >> > this small ?y does not undergo any obvious contraction, as its speed is
> >> > low compared to the tangential speed.
> >>
> >> Sure.
> >>
> >> But you certainly don't want to be an observer on a rotating disk, which
> >> has tangential velocity in the relativistic realm.
> >>
> >> That would be like sitting on a carussel, which runs insanely fast.
> >>
> >> You will be shot from that disk like a cannon ball.
> >>
> >> Therefore only very slow rotation is somehow feasable (for human
> >> observers), which is far far far from relativity velocity.
> >>
> >>
> >> > If we decompose the movement, we then understand that the part ?y does
> >> > not contract or only slightly, and that the part ?x contracts greatly at
> >> > relativistic speed.
> >>
> >> If you want to enter the realm of special relativity, you need extremely
> >> high angular velocity or extremely large disks (or both).
> >>
> >> This will bring the 'rigid' disk into its critical realm, where tensions
> >> are far greater than the strength of the material could possibly be.
> >>
> >> But at least: the radius will not shrink nor will the circumference.
> >>
> >> (more likely: that disk will break)
> >>
> >>
> >> > The observable residual velocity vector is therefore deviated inwards.
> >> >
> >> > This can explain why the disk ALSO contracts at the level of the
> >> > radius, and why there is no paradox, since pi remains invariant in this
> >> > case.
> >>
> >> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> >> to say.
> >
> > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > It makes it obvious that you can not deal with the situation
> > in simple-minded and ad-hoc ways.
> > (not even with extreme idealisations)
> >
> > To Einstein it pointed the way to the need for non-Euclidean geometry.
> >
> > Jan
> When physicists don't know how to answer, they say "It's not Euclidean
> geometry."

No, that's not at all why they say it. There are very concrete reasons
for saying this.

> But they don't know how to clearly explain what it is.

They do. But, as Goethe has wisely observed, "to read a good book is
as difficult as to write one".

> If we talk to them about the Ehrenfest paradox, they don't know how to
> answer.

They do. Reread the Goethe quote above.

In general, stop assuming that if you don't understand something,
it must necessarily be wrong and everyone else is an idiot. This is
infantile thinking.

--
Jan

On Thursday, December 28, 2023 at 10:14:13 AM UTC-8, Ross Finlayson wrote:
> On Thursday, December 28, 2023 at 4:18:04 AM UTC-8, J. J. Lodder wrote:
> > Thomas Heger <ttt...@web.de> wrote:
> >
> > > Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > > > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > > >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > > >>> Thomas Heger <ttt...@web.de> wrote:
> > > >>>
> > > >>>> Hi NG
> > > >>>>
> > > >>>> I had recently read a book about GR and found it astonishing, what
> > > >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > > >>>>
> > > >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>> To me it is selfevident, that observers on a rotating disk would
> > > >>>> encounter some kind of outwards acceleration, if that disk rotates.
> > > >>>
> > > >>> It was evident then, and it should be evident now,
> > > >>> is that special relativity by itself
> > > >>> is not adequate to deal with the situation.
> > > >>> That's all there is to it,
> > > >>>
> > > >>> Jan
> > > >>
> > > >> Coward, coward!
> > > >>
> > > >> R.H.
> > > >
> > > > For me, no matter how many times I tossed the problem around for
> > > > decades, it always ended up that both the circumference AND the radius
> > > > contracted.
> > > >
> > > > Let's take for example a point A which passes at the top of the record
> > > > at 12 o'clock position.
> > > >
> > > > It has practically zero velocity in "y" at this instant, and its
> > > > entire velocity vector is practically in "x".
> > > >
> > > > But we are in a rotating frame of reference, and not in a purely
> > > > Galilean frame of reference.
> > >
> > >
> > > Sure, a rotating frame of reference is not inertial.
> > >
> > > The reason: rotation is causing acceleration and that is measurable
> > > without any reference.
> > >
> > > So, rotation is 'absolute', while inertial movement is 'relative'.
> > >
> > > We know this 'absoluteness' from the realm of missile guidence or
> > > satelite control.
> > >
> > > They use laser gyroscopes, which can detect very small rotations.
> > >
> > > For rotation you don't need to see a reference point, because rotation
> > > causes acceleration. And acceleration is not inertial.
> > >
> > > > This mini component in y still exists, and it should be noted that
> > > > this small ?y does not undergo any obvious contraction, as its speed is
> > > > low compared to the tangential speed.
> > >
> > > Sure.
> > >
> > > But you certainly don't want to be an observer on a rotating disk, which
> > > has tangential velocity in the relativistic realm.
> > >
> > > That would be like sitting on a carussel, which runs insanely fast.
> > >
> > > You will be shot from that disk like a cannon ball.
> > >
> > > Therefore only very slow rotation is somehow feasable (for human
> > > observers), which is far far far from relativity velocity.
> > >
> > >
> > > > If we decompose the movement, we then understand that the part ?y does
> > > > not contract or only slightly, and that the part ?x contracts greatly at
> > > > relativistic speed.
> > >
> > > If you want to enter the realm of special relativity, you need extremely
> > > high angular velocity or extremely large disks (or both).
> > >
> > > This will bring the 'rigid' disk into its critical realm, where tensions
> > > are far greater than the strength of the material could possibly be.
> > >
> > > But at least: the radius will not shrink nor will the circumference.
> > >
> > > (more likely: that disk will break)
> > >
> > >
> > > > The observable residual velocity vector is therefore deviated inwards.
> > > >
> > > > This can explain why the disk ALSO contracts at the level of the
> > > > radius, and why there is no paradox, since pi remains invariant in this
> > > > case.
> > >
> > > I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > > to say.
> > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > It makes it obvious that you can not deal with the situation
> > in simple-minded and ad-hoc ways.
> > (not even with extreme idealisations)
> >
> > To Einstein it pointed the way to the need for non-Euclidean geometry.
> >
> > Jan
> What Einstein points to is his "bridge", that most relate to Einstein-Podolsky-Rosen,
> but which really is about the interface the linear and rotational, also classical.
>
> That is, Einstein's bridge is about his theory's applications to kinetics and kinematics,
> deeply.
>
> The "non-Euclidean" is just transforms reflecting either side
> coordinate settings, of what are wells in the well model,
> the metrics, a metric, in our gauge theory, a gauge, the R-gauge.
>
> The real gauge, ....
>
> (Though spelled "gauge" it's pronounced "gage" not "gouge".)
>
> ...

Moment and Motion: fixed and free information

https://www.youtube.com/watch?v=rLDJXdOj_C8

The moment the instant, the moment the action, foundations and the textual,
Bohm, hidden variables theories, relevance and language, free wave information,
statistical methods, the physical quantity tetrad, large numbers and convergence,
Einstein-Podolsky-Rosen, condensed matter vis-a-vis kinematics, Bohr and Born,
continua, deconstructive analysis with a principled approach, Einstein's physicist
and philosopher team, Pauli and Heisenberg principles of uncertainty and certainty,
practical historical theories of force, topology via logic, space planning, fundament
and firmament, horizon and perspective, the Earth, the Earth station, Greenwich and
Colorado, a note on style and the comma, astronomy as a milieu, horizontal and spherical
optical effects, Earth in the ecliptic, word and number sense, uncertainty and chance,
laws of large numbers, the continuum as a concept, the learned canon, Heraclitus' Hilbert's,
Fourier-style analysis, relevance in the absolute.

....

On Thursday, December 28, 2023 at 3:03:44 PM UTC-8, JanPB wrote:
> On Thursday, December 28, 2023 at 6:19:48 AM UTC-8, Richard Hachel wrote:
> > Le 28/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > > Thomas Heger <ttt...@web.de> wrote:
> > >
> > >> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > >> > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > >> >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > >> >>> Thomas Heger <ttt...@web.de> wrote:
> > >> >>>
> > >> >>>> Hi NG
> > >> >>>>
> > >> >>>> I had recently read a book about GR and found it astonishing, what
> > >> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > >> >>>>
> > >> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > >> >>>>
> > >> >>>>
> > >> >>>>
> > >> >>>> To me it is selfevident, that observers on a rotating disk would
> > >> >>>> encounter some kind of outwards acceleration, if that disk rotates.
> > >> >>>
> > >> >>> It was evident then, and it should be evident now,
> > >> >>> is that special relativity by itself
> > >> >>> is not adequate to deal with the situation.
> > >> >>> That's all there is to it,
> > >> >>>
> > >> >>> Jan
> > >> >>
> > >> >> Coward, coward!
> > >> >>
> > >> >> R.H.
> > >> >
> > >> > For me, no matter how many times I tossed the problem around for
> > >> > decades, it always ended up that both the circumference AND the radius
> > >> > contracted.
> > >> >
> > >> > Let's take for example a point A which passes at the top of the record
> > >> > at 12 o'clock position.
> > >> >
> > >> > It has practically zero velocity in "y" at this instant, and its
> > >> > entire velocity vector is practically in "x".
> > >> >
> > >> > But we are in a rotating frame of reference, and not in a purely
> > >> > Galilean frame of reference.
> > >>
> > >>
> > >> Sure, a rotating frame of reference is not inertial.
> > >>
> > >> The reason: rotation is causing acceleration and that is measurable
> > >> without any reference.
> > >>
> > >> So, rotation is 'absolute', while inertial movement is 'relative'.
> > >>
> > >> We know this 'absoluteness' from the realm of missile guidence or
> > >> satelite control.
> > >>
> > >> They use laser gyroscopes, which can detect very small rotations.
> > >>
> > >> For rotation you don't need to see a reference point, because rotation
> > >> causes acceleration. And acceleration is not inertial.
> > >>
> > >> > This mini component in y still exists, and it should be noted that
> > >> > this small ?y does not undergo any obvious contraction, as its speed is
> > >> > low compared to the tangential speed.
> > >>
> > >> Sure.
> > >>
> > >> But you certainly don't want to be an observer on a rotating disk, which
> > >> has tangential velocity in the relativistic realm.
> > >>
> > >> That would be like sitting on a carussel, which runs insanely fast.
> > >>
> > >> You will be shot from that disk like a cannon ball.
> > >>
> > >> Therefore only very slow rotation is somehow feasable (for human
> > >> observers), which is far far far from relativity velocity.
> > >>
> > >>
> > >> > If we decompose the movement, we then understand that the part ?y does
> > >> > not contract or only slightly, and that the part ?x contracts greatly at
> > >> > relativistic speed.
> > >>
> > >> If you want to enter the realm of special relativity, you need extremely
> > >> high angular velocity or extremely large disks (or both).
> > >>
> > >> This will bring the 'rigid' disk into its critical realm, where tensions
> > >> are far greater than the strength of the material could possibly be.
> > >>
> > >> But at least: the radius will not shrink nor will the circumference.
> > >>
> > >> (more likely: that disk will break)
> > >>
> > >>
> > >> > The observable residual velocity vector is therefore deviated inwards.
> > >> >
> > >> > This can explain why the disk ALSO contracts at the level of the
> > >> > radius, and why there is no paradox, since pi remains invariant in this
> > >> > case.
> > >>
> > >> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > >> to say.
> > >
> > > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > > It makes it obvious that you can not deal with the situation
> > > in simple-minded and ad-hoc ways.
> > > (not even with extreme idealisations)
> > >
> > > To Einstein it pointed the way to the need for non-Euclidean geometry..
> > >
> > > Jan
> > When physicists don't know how to answer, they say "It's not Euclidean
> > geometry."
> No, that's not at all why they say it. There are very concrete reasons
> for saying this.
> > But they don't know how to clearly explain what it is.
> They do. But, as Goethe has wisely observed, "to read a good book is
> as difficult as to write one".
> > If we talk to them about the Ehrenfest paradox, they don't know how to
> > answer.
> They do. Reread the Goethe quote above.
>
> In general, stop assuming that if you don't understand something,
> it must necessarily be wrong and everyone else is an idiot. This is
> infantile thinking.
>
> --
> Jan

Go with what you know, right.

On Friday 29 December 2023 at 00:03:44 UTC+1, JanPB wrote:
> On Thursday, December 28, 2023 at 6:19:48 AM UTC-8, Richard Hachel wrote:
> > Le 28/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > > Thomas Heger <ttt...@web.de> wrote:
> > >
> > >> Am 27.12.2023 um 03:21 schrieb Richard Hachel:
> > >> > Le 25/12/2023 à 17:26, Richard Hachel a écrit :
> > >> >> Le 24/12/2023 à 13:18, nos...@de-ster.demon.nl (J. J. Lodder) a écrit :
> > >> >>> Thomas Heger <ttt...@web.de> wrote:
> > >> >>>
> > >> >>>> Hi NG
> > >> >>>>
> > >> >>>> I had recently read a book about GR and found it astonishing, what
> > >> >>>> Einstein and Ehrenfest said about observers on a rotating disk.
> > >> >>>>
> > >> >>>> https://en.wikipedia.org/wiki/Ehrenfest_paradox
> > >> >>>>
> > >> >>>>
> > >> >>>>
> > >> >>>> To me it is selfevident, that observers on a rotating disk would
> > >> >>>> encounter some kind of outwards acceleration, if that disk rotates.
> > >> >>>
> > >> >>> It was evident then, and it should be evident now,
> > >> >>> is that special relativity by itself
> > >> >>> is not adequate to deal with the situation.
> > >> >>> That's all there is to it,
> > >> >>>
> > >> >>> Jan
> > >> >>
> > >> >> Coward, coward!
> > >> >>
> > >> >> R.H.
> > >> >
> > >> > For me, no matter how many times I tossed the problem around for
> > >> > decades, it always ended up that both the circumference AND the radius
> > >> > contracted.
> > >> >
> > >> > Let's take for example a point A which passes at the top of the record
> > >> > at 12 o'clock position.
> > >> >
> > >> > It has practically zero velocity in "y" at this instant, and its
> > >> > entire velocity vector is practically in "x".
> > >> >
> > >> > But we are in a rotating frame of reference, and not in a purely
> > >> > Galilean frame of reference.
> > >>
> > >>
> > >> Sure, a rotating frame of reference is not inertial.
> > >>
> > >> The reason: rotation is causing acceleration and that is measurable
> > >> without any reference.
> > >>
> > >> So, rotation is 'absolute', while inertial movement is 'relative'.
> > >>
> > >> We know this 'absoluteness' from the realm of missile guidence or
> > >> satelite control.
> > >>
> > >> They use laser gyroscopes, which can detect very small rotations.
> > >>
> > >> For rotation you don't need to see a reference point, because rotation
> > >> causes acceleration. And acceleration is not inertial.
> > >>
> > >> > This mini component in y still exists, and it should be noted that
> > >> > this small ?y does not undergo any obvious contraction, as its speed is
> > >> > low compared to the tangential speed.
> > >>
> > >> Sure.
> > >>
> > >> But you certainly don't want to be an observer on a rotating disk, which
> > >> has tangential velocity in the relativistic realm.
> > >>
> > >> That would be like sitting on a carussel, which runs insanely fast.
> > >>
> > >> You will be shot from that disk like a cannon ball.
> > >>
> > >> Therefore only very slow rotation is somehow feasable (for human
> > >> observers), which is far far far from relativity velocity.
> > >>
> > >>
> > >> > If we decompose the movement, we then understand that the part ?y does
> > >> > not contract or only slightly, and that the part ?x contracts greatly at
> > >> > relativistic speed.
> > >>
> > >> If you want to enter the realm of special relativity, you need extremely
> > >> high angular velocity or extremely large disks (or both).
> > >>
> > >> This will bring the 'rigid' disk into its critical realm, where tensions
> > >> are far greater than the strength of the material could possibly be.
> > >>
> > >> But at least: the radius will not shrink nor will the circumference.
> > >>
> > >> (more likely: that disk will break)
> > >>
> > >>
> > >> > The observable residual velocity vector is therefore deviated inwards.
> > >> >
> > >> > This can explain why the disk ALSO contracts at the level of the
> > >> > radius, and why there is no paradox, since pi remains invariant in this
> > >> > case.
> > >>
> > >> I have absolutely no idea, what Einstein and Ehrenfest actually wanted
> > >> to say.
> > >
> > > Einstein and Ehrenfest just took the 'paradox' as heuristics.
> > > It makes it obvious that you can not deal with the situation
> > > in simple-minded and ad-hoc ways.
> > > (not even with extreme idealisations)
> > >
> > > To Einstein it pointed the way to the need for non-Euclidean geometry..
> > >
> > > Jan
> > When physicists don't know how to answer, they say "It's not Euclidean
> > geometry."
> No, that's not at all why they say it. There are very concrete reasons
> for saying this.

Very concrete reasons: basic mathematics didn't fit the delusions
of an insane crazie, basic mathematics must be wrong.

Le 28/12/2023 à 22:31, wugi a écrit :

> That's what I've tried to study in my video here:
> https://www.youtube.com/watch?v=AflRNMIMLpU

Did you personally make this video?

R.H.

Le 28/12/2023 à 22:31, wugi a écrit :

> That's what I've tried to study in my video here:

>
<http://youtu.be/AflRNMIMLpU>

Did you personally make this video?

R.H.

--
<http://news2.nemoweb.net/?DataID=RklVl6ckDoLKgnz21VEpAqyvI04@jntp>

Op 29/12/2023 om 8:42 schreef Richard Hachel:
> Le 28/12/2023 à 22:31, wugi a écrit :
>
>> That's what I've tried to study in my video here:
>> https://www.youtube.com/watch?v=AflRNMIMLpU
>
> Did you personally make this video?

Yes of course. (apart from the music:)

--
guido wugi