Direct observation of length contraction

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Dono

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Jan 29, 2008, 1:52:36 PM1/29/08
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The FAQ claims that there are no direct tests of length contraction.
I may have found one:

http://prola.aps.org/abstract/PRL/v75/i7/p1372_1

xxein

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Jan 29, 2008, 5:23:26 PM1/29/08
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xxein: Grasping at straws.

I remember a common (in space perhaps) observation that supports LC.
Perhaps a reader can cite.

I don't need a proof for myself. Any comprehensive, logical theory
discovers this as a necessary resultant. But it is still
misunderstood by most all theories.

N:dlzc D:aol T:com (dlzc)

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Jan 29, 2008, 9:16:25 PM1/29/08
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Dear Dono:

"Dono" <sa...@comcast.net> wrote in message
news:7626d732-81e0-4e16...@i29g2000prf.googlegroups.com...


> The FAQ claims that there are no direct tests of
> length contraction. I may have found one:
>
> http://prola.aps.org/abstract/PRL/v75/i7/p1372_1

http://physics.weber.edu/schroeder/mrr/MRRtalk.html
... nothing to measure in magnetism *except* length contraction,
because the charge is known...

David A. Smith


Dono

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Jan 29, 2008, 9:23:48 PM1/29/08
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On Jan 29, 6:16 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>
wrote:

This is a very bad article. Hans de Vries completely rewrote this
article . He does not use length contraction in his explanation . See
here:

http://chip-architect.com/news/2007_02_27_Magnetism_as_a_Relativistic_side_effect.html

Click on the pdf.

N:dlzc D:aol T:com (dlzc)

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Jan 29, 2008, 9:34:27 PM1/29/08
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Dear Dono:

"Dono" <sa...@comcast.net> wrote in message

news:d88cc742-f703-4ba7...@y5g2000hsf.googlegroups.com...


> On Jan 29, 6:16 pm, "N:dlzc D:aol T:com \(dlzc\)"
> <dl...@cox.net>
> wrote:
>> Dear Dono:
>>
>> "Dono" <sa...@comcast.net> wrote in message
>>
>> news:7626d732-81e0-4e16...@i29g2000prf.googlegroups.com...
>>
>> > The FAQ claims that there are no direct tests of
>> > length contraction. I may have found one:
>>
>> >http://prola.aps.org/abstract/PRL/v75/i7/p1372_1
>>
>> http://physics.weber.edu/schroeder/mrr/MRRtalk.html
>> ... nothing to measure in magnetism *except* length
>> contraction, because the charge is known...
>

> This is a very bad article. Hans de Vries completely
> rewrote this article . He does not use length contraction
> in his explanation . See here:
>
> http://chip-architect.com/news/2007_02_27_Magnetism_as_a_Relativistic_side_effect.html
>
> Click on the pdf.

Yes, he says it is length contraction. "A relativistic side
effect..." What he is doing is generalizing the mathematics from
what Purcell did.

David A. Smith


Dono

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Jan 29, 2008, 9:38:06 PM1/29/08
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On Jan 29, 6:34 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>

wrote:
> Dear Dono:
>
> "Dono" <sa...@comcast.net> wrote in message
>
> news:d88cc742-f703-4ba7...@y5g2000hsf.googlegroups.com...
>
>
>
> > On Jan 29, 6:16 pm, "N:dlzc D:aol T:com \(dlzc\)"
> > <dl...@cox.net>
> > wrote:
> >> Dear Dono:
>
> >> "Dono" <sa...@comcast.net> wrote in message
>
> >>news:7626d732-81e0-4e16...@i29g2000prf.googlegroups.com...
>
> >> > The FAQ claims that there are no direct tests of
> >> > length contraction. I may have found one:
>
> >> >http://prola.aps.org/abstract/PRL/v75/i7/p1372_1
>
> >>http://physics.weber.edu/schroeder/mrr/MRRtalk.html
> >> ... nothing to measure in magnetism *except* length
> >> contraction, because the charge is known...
>
> > This is a very bad article. Hans de Vries completely
> > rewrote this article . He does not use length contraction
> > in his explanation . See here:
>
> >http://chip-architect.com/news/2007_02_27_Magnetism_as_a_Relativistic...

>
> > Click on the pdf.
>
> Yes, he says it is length contraction. "A relativistic side
> effect..." What he is doing is generalizing the mathematics from
> what Purcell did.
>
> David A. Smith

Hans' demonstration does not use length contraction, please read
carefully.

N:dlzc D:aol T:com (dlzc)

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Jan 29, 2008, 11:08:51 PM1/29/08
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Dear Dono:

"Dono" <sa...@comcast.net> wrote in message

news:6be333b9-75bd-4e7a...@k2g2000hse.googlegroups.com...

> Hans' demonstration does not use length contraction,
> please read carefully.

Read again. Started with a particle with a velocity, and got a
net charge density change. Length contraction. Since length
contraction and time dilation are two sides of the same coin, he
also arrives (explicity) at time dilation.

Choose your weapons, but they are all the same.

David A. Smith


xxein

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Jan 29, 2008, 11:34:36 PM1/29/08
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On Jan 29, 11:08 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>
> David A. Smith- Hide quoted text -
>
> - Show quoted text -

xxein: LC and TD are not two sides of the same coin. Their
dimensional aspects demand separation from such a physical and
mathematical construct.

Jeckyl

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Jan 29, 2008, 11:41:15 PM1/29/08
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"xxein" <xx...@comcast.net> wrote in message
news:cd819dcb-7c24-4aac...@v67g2000hse.googlegroups.com...

Well .. in one sense they are .. in that they need to go together .. along
with relativity of simultaneity. If you have one without the others, then
things fall apart and make no sense. Many anti-relativists fall into that
trap. Basically all three are results of minkowski space / lorentz
transforms .. that is the 'coin' that they can be considered 'sides' of.


N:dlzc D:aol T:com (dlzc)

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Jan 30, 2008, 12:00:24 AM1/30/08
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Dear xxein:

"xxein" <xx...@comcast.net> wrote in message
news:cd819dcb-7c24-4aac...@v67g2000hse.googlegroups.com...

...


> xxein: LC and TD are not two sides of the
> same coin. Their dimensional aspects
> demand separation from such a physical and
> mathematical construct.

We see the lifetime of the muon "time dilated". The muon sees
our atmosphere as "length contracted" to a few tens of meters,
and its lifetime unaffected.

Same coin, two sides.

David A. Smith


Dono

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Jan 30, 2008, 12:01:19 AM1/30/08
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On Jan 29, 8:08 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>

I read it several times , perhaps you will care to point out the exact
formula where Hans invokes length contraction. They are numbered, so
it should be easy.

N:dlzc D:aol T:com (dlzc)

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Jan 30, 2008, 8:22:21 AM1/30/08
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Dear Dono:

"Dono" <sa...@comcast.net> wrote in message

news:0a4c7819-a92c-4bcd...@l32g2000hse.googlegroups.com...

> I read it several times , perhaps you will care to point out
> the exact formula where Hans invokes length contraction.
> They are numbered, so it should be easy.

between (1) and (2), and shown in Figure 1.

He handwaves at equations (2), and notes that he likes the shape
of the time dilation formula, because it has the exact term
(v/c^2) that he is looking for. When the length contraction
formula does also:

x = gamma * (x' - vt') equates to ...

(gamma * x' - x) / (t' * c^2) = v / c^2

... now compare that to the resultant of his (1)
qL / I = v / c^2

It is the same coin, Dono. It has *two* sides. One is length
contraction, the other time dilation.

David A. Smith


Dono

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Jan 30, 2008, 10:16:37 AM1/30/08
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On Jan 30, 5:22 am, "N:dlzc D:aol T:com \(dlzc\)" <dl...@cox.net>

This is relativity of simulatneity, all right. Note his title as well.
You are wasting my time (and yours)

Jeckyl

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Jan 30, 2008, 5:06:44 PM1/30/08
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"Dono" <sa...@comcast.net> wrote in message
news:978fe97d-2b98-464b...@v67g2000hse.googlegroups.com...

I agree with Dono .. the analysis does not make use of length contraction
per-se. One could possibly say that if one is using one part of the Lorentz
transform, one must be using all of it, so implicitly it is using length
contraction .. but that's not a direct use (as is what appears to have been
claimed).


Tom Roberts

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Feb 2, 2008, 8:03:22 AM2/2/08
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I disagree with their analysis and claims, and do not consider this to
be truly Lorentz contraction. That's because their factor is
sqrt(1-v^2/cbar^2) where cbar is the speed of light in their junction
(about 0.05 c). True Lorentz contraction involves the vacuum speed of
light, c, not cbar. I consider this an electromagnetic phenomenon that
uses a formula similar to Lorentz contraction, and not Lorentz
contraction itself. This is supported by their entire approach, which is
based on wave equations in the junction -- clearly electromagnetic
phenomena, and not the underlying structure of spacetime -- their wave
equation is NOT Lorentz invariant, as it inherently involves a special
frame, the rest frame of the junction.

The local structure of spacetime is related to c (the invariant speed of
the Lorentz transform), not any electromagnetic properties of materials
or optical media. Lorentz contraction is related to the structure of
spacetime, not any materials or media.


Tom Roberts

Pentcho Valev

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Feb 2, 2008, 10:10:59 AM2/2/08
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On Feb 2, 3:03 pm, Tom Roberts <tjroberts...@sbcglobal.net> wrote in
sci.physics.relativity:

But Roberts Roberts this contradicts a recent breathtaking discovery
of yours that confirmed an earlier breathtaking discovery of Jean-Marc
Levy-Leblond:

Tom Roberts' breathtaking discovery: Even if "light in vacuum does not
travel at the invariant speed of the Lorentz transform", Special
Relativity "would be unaffected":

http://groups.google.ca/group/sci.physics.relativity/browse_frm/thread/8034dc146100e32c?
Tom Roberts, Feb 1, 2006: "If it is ultimately discovered that the
photon has a nonzero mass (i.e. light in vacuum does not travel at the
invariant speed of the Lorentz transform), SR would be unaffected but
both Maxwell's equations and QED would be refuted (or rather, their
domains of applicability would be reduced)."

http://o.castera.free.fr/pdf/chronogeometrie.pdf
Jean-Marc Levy-Leblond: "D'autre part, nous savons aujourd'hui que
l'invariance de la vitesse de la lumiere est une consequence de la
nullite de la masse du photon. Mais, empiriquement, cette masse, aussi
faible soit son actuelle borne superieure experimentale, ne peut et ne
pourra jamais etre consideree avec certitude comme rigoureusement
nulle. Il se pourrait meme que de futures mesures mettent en evidence
une masse infime, mais non-nulle, du photon ; la lumiere alors n'irait
plus a la "vitesse de la lumiere", ou, plus precisement, la vitesse de
la lumiere, desormais variable, ne s'identifierait plus a la vitesse
limite invariante. Les procedures operationnelles mises en jeu par le
"second postulat" deviendraient caduques ipso facto. La theorie elle-
meme en serait-elle invalidee ? Heureusement, il n'en est rien ; mais,
pour s'en assurer, il convient de la refonder sur des bases plus
solides, et d'ailleurs plus economiques. En verite, le "premier
postulat" suffit, a la condition de l'exploiter a fond."

http://o.castera.free.fr/pdf/onemorederivation.pdf
Jean-Marc Levy-Leblond: "This is the point of view from wich I intend
to criticize the overemphasized role of the speed of light in the
foundations of the special relativity, and to propose an approach to
these foundations that dispenses with the hypothesis of the invariance
of c....We believe that special relativity at the present time stands
as a universal theory discribing the structure of a common space-time
arena in which all fundamental processes take place....The evidence of
the nonzero mass of the photon would not, as such, shake in any way
the validity of the special relativity. It would, however, nullify all
its derivations which are based on the invariance of the photon
velocity."

Pentcho Valev
pva...@yahoo.com

Dono

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Feb 3, 2008, 1:39:20 AM2/3/08
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Good point.

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