🚀 go-pugleaf

On Nov 8, 10:28 am, Pentcho Valev <pva...@yahoo.com> wrote:
> On Nov 8, 9:14 am, Don Stockbauer <donstockba...@hotmail.com> wrote in
> sci.physics.relativity:
>
>
>
>
>
> > On Nov 8, 12:49 am, Pentcho Valev <pva...@yahoo.com> wrote:
>
> > > On 7 Nov, 21:01, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
> > > > In SR, neither "length contraction"
> > > > nor "time dilation" are physical -- they are purely geometrical. A
> > > > moving ruler does not physically get any shorter, it is merely MEASURED
> > > > shorter by an observer relative to whom it is moving along its length.
> > > > Ditto for clock tick-rates.
>
> > > >         Simple example: take two meter sticks, A and B, and place
> > > >         them in a V on the ground. Project the end of each
> > > >         perpendicularly onto the other. The length of A projected
> > > >         onto B is less than 1 meter; the length of B projected
> > > >         onto A is likewise less than 1 meter. Yet NEITHER stick
> > > >         is physically shorter. This is easily recognizable as a
> > > >         geometric projection that does not affect the meter sticks
> > > >         at all. In SR, "length contraction" and "time dilation"
> > > >         are PRECISELY the same -- geometric projections that do
> > > >         not affect objects at all.
>
> > > Roberts Roberts you are paid for teaching that length contraction and
> > > time dilation are "purely geometrical", not "physical", and so teach
> > > your French brothers - Thibault Damour and Gilles Cohen-Tannoudji for
> > > instance. However most brothers in Einstein criminal cult teach the
> > > opposite Roberts Roberts - they are paid for explaining how a long
> > > train can be trapped inside a short tunnel, how a 80m long pole can be
> > > trapped inside a 40m long barn, and, what is most important Roberts
> > > Roberts, those brothers of yours tell the "story of what causes the
> > > particles to get closer together, and so what causes the rod to
> > > shrink":
>
> > >http://groups.google.ca/group/sci.physics.relativity/browse_frm/threa...
>
> > > Who gives the money for all those good salaries Roberts Roberts?
> > > Taxpayers in Einstein zombie world?
>
> > > Pentcho Valev
>
> > Only Napoleon held aloof. He had declared himself against the windmill
> > from the start.  One day, however, he arrived unexpectedly to examine
> > the plans. He walked heavily round the shed, looked closely at every
> > detail of the plans and snuffed at them once or twice, then stood for
> > a little while contemplating them out of the corner of his eye; then
> > suddenly he lifted his leg, urinated over the plans, and walked out
> > without uttering a word.
>
> A nice story but now you shall return to the problem your masters have
> not solved yet:
>
> http://ndpr.nd.edu/review.cfm?id=6603
> "There are many things I might be asking when I ask someone to explain
> length contraction. I might be asking, "Why do different inertial
> observers (who are not at relative rest) disagree about the length of
> a given (inertially moving) rod?" Or I might be asking, "Why is a
> moving rod shorter than its stationary counterpart (of the same proper
> length)?" Or I might be asking, "If you take a rod that is initially
> at rest (in your frame of reference), and accelerate it, why is it
> shorter after you accelerate it than it was before you accelerated
> it?"......I'm not sure what Brown thinks about geometrical answers to
> the first why-question, but he certainly thinks that GEOMETRICAL
> ANSWERS TO THE SECOND TWO WHY-QUESTIONS ARE BAD EXPLANATIONS. He
> thinks that good answers to these questions say something about the
> way in which the forces holding the parts of the rod together depend
> on velocity of the rod. Only that is a story of what causes the
> particles to get closer together, and so what causes the rod to
> shrink."
>
> Pentcho Valev- Hide quoted text -
>
> - Show quoted text -

The acceleration of the rod is only incedental, it is required to
place the rod in a state of motion wrt the observer. The relative
motion is the relevenat factor.  If the observer of the rod
accelerates instead he will see the same contraction of the rod as
when the rod is accelerated while he stays put.  Because of this the
foreshortening of the rod cannot be due to anything other than the
change in perspective of it.  What this means is that by raising the
velocity of the rod to greater than zero along its length, then our
perspective of the rod must change.  What has really changed is not
the proper length of the rod, but rather its simultaneous length.
Observers in K and K' don't agree about the simulatneous length of the
rod, but both will agree on its proper length.

The reason that the moving observer finds the length of the rod less
is that he marks the time that each end passes some reference point
differently than an observer who is at rest wrt the rod.  Length
contraction is thus an artifact that arises from the relativity of
simultaneity.

This is however in contradiction to the relativity principle, since
the latter requires that the laws of physics be concerned with
invariant properties.
Since the simulatneous length of the rod isn't invariant, then
simulatneous length is not valid wrt the RP. It is instead only a
measurement artifact, i.e. it doesn't reflect a true property fo the
rod, but only a visual perspective, that is in a sense no different
than the percieved shortening of rods along y as a function of
distance from the observer.

I'm working on a true invariant solution. Covariance and anti-symetric
tensors don't provide what we're after, that being Laws of physics in
which not only the equations are identical independently of reference
frames, but in which the variables entered are also identical. Once we
have that, then we can treat perspective separately, accounting for
what the observers will measure. GR, especially because it doesn't
treat em fields as space-time curvature, and because it also regards
the universe as a continuum, cannot be fundamental.