Re: Direct observation of length contraction
Pentcho Valev
sci.physics.relativity:
> Dono wrote:
> > 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
>
> 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.
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