Re: The true crackpots


PD wrote:
> kenseto wrote:
> > "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> > news:1128178941.275246.204110@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > >
> > > mluttgens@xxxxxxxxxx wrote:
> > > > PD wrote:
> > > >
> > > > "... it is clear why the length of an object is *not* an
> > > > inherent property of an object and it is much more easily grasped why
> > > > this quantity is *of course* observer-dependent and, finally, why two
> > > > observers can view each other's (identical) objects and each see them
> > > > as shorter and that's not a problem. That is, it no longer is a
> > > > "logical aberration".
> > > >
> > > > Yes, it is a logical aberration, because those observers apply SR,
> > >
> > > No. Their measurements are their measurements, their observations are
> > > their observations. They are not applying SR in any way to make those
> > > measurements.
> > >
> > > > which only takes into consideration the relative motion between them,
> > > > and ignores the possibility that they could move at different
> > > > velocities wrt a same rest frame (like the track wrt which two trains
> > > > are moving). Then, one of them could view the other as longer.
> > >
> > > Not on your life. Not without making a *correction* that *you* are
> > > imposing to their measurements. What SR predicts is what the observers
> > > will measure *without* any correction or manipulation. That is the part
> > > you fail to understand.
> >
> > What is the justification that an SR observer will measure all rod moving
> > wrt him are contracted.
>
> In brief, the justification is that the *definition* of length relies
> on simultaneity: the locations of the two ends of a moving rod must be
> measured at the same time for the measurement to mean anything. The
> problem is that there is no way to define absolute simultaneity. Two
> events that are simultaneous to observer A will not be simultaneous to
> observer B, and vice versa. Since simultaneity is a
> reference-frame-dependent property, so is length. There is no deeper
> physical meaning to the length of a rod. Now, if you'd like for me to
> expand on this in detail, we can do that.
>
> > Also how do you know what the observer measure is
> > what SR predicts??
>
> Uh, measurement, Ken. In an experiment.

Could you propose a design for such experiment? I am looking forward to
it.

Marcel Luttgens

.

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