sci.physics.relativity

On Mar 6, 8:17=A0am, "kenseto" wrote:
> "PD" wrote in message
>
> news:d98b978b-1669-4a52-ba6b-b17f645c12f2@...
> On Mar 5, 9:31 am, "kenseto" wrote:
>
> > The SRians in this NG claim that a longer pole can be trapped inside a
> > shorter barn from the barn frame point of view.
> >Please define term "trapped". Does this mean
> >a) that there is an instant when both ends of the pole are inside the
> >barn at the same time?
>
> Yes.

OK.

>
> , or
> b) that the doors of the barn can be shut and left shut overnight and
> the pole will still be inside in the morning?
>
> No idiot the pole is moving.
>
> >> This can only happen if
> >> there is real physical contraction
> >Please define term "real physical contraction". This has no meaning as
> >it is.
>
> The longer pole length can be inside the shorter length barn for a brief
> period without hitting the simultaneously closed doors. That's real physic=
al
> contraction.

No, define what real physical contraction means in general, not just
in this case.

>
> >> of the pole from the barn frame point of
> >> view. OTOH SR deny physical length contraction.
> >Please define term "physical length contraction". This has no meaning
> >as it is.
>
> When you freeze a pole that's real physical length contraction.

OK, that's one example. Surely there are other ways. What's real
physical length contraction in general imply to you?

>
> >> It says that length
> >> contraction is a geometric projection effect.
> >But 4D onto 3D, not 3D onto 2D. And the 4D isn't all spatial and
> >Euclidean, either.
>
> There is no 4D.

Well, that's the projection that everyone's been trying to explain to
you. If you don't understand it, then stop quoting it.

> It is made up by you SRians to explain that projection
> effect can be physically real or physically not real.
>
> > Much like
>
> Much like. Not exactly like. At all.
>
>
>
> > that you see me to
> > be shorter from a distance and you see me to be shorter from a distance.=

> It
> > seems that the SRians want to have it both way.
>
> > The proper SR interpretation should be as follows:
> > 1. There is no physical length contraction.
> > 2. All observers will say that the physical length of the pole remains
> > unchanged.
> > 3. The barn observer will say that the light path length of the moving
> pole
> > is different than the light path length of the pole if it is at rest in
> the
> > barn frame.
>
> None of these "interpretations" mean anything until you define
> "physical length contraction", "physical length", "light path length".
>
> Physical length contraction means the physical length of a pole is shorter=

> than its proper length.
> An example of physical contraction is freezing a
> metal ruler.

What are other ways? What has to happen in general for you to
recognize that a physical contraction has happened?

Certainly the pole has not been frozen in this case. If that's the
only way to physically contract the pole, then that hasn't happened.

> Physical length: It is the length of a physical ruler at STP.

I'm sorry, how does that definition work for finding the physical
length of a squid or a banana or a pole or a barn?

> Light path length: It is the distance light need to travel to cover the
> physical length of a rod.

Which is the same for stationary objects, right?

I gather that what you are defining as light path length for a
*moving* object is the distance light has to go if it starts at one
end of the rod at one instant and then reaches the other end of the
rod at a later instant. If this is the correct definition of what you
mean by light path length, then there are *two* light path lengths of
a rod, depending on whether the light starts at the back of the rod
and races to catch up with the front of the rod, or whether the light
starts at the front of the rod and races to meet the back of the rod.
Which light path length is right, and why?

> In the observer's frame SR and IRT assumes that
> the light path length of a rod is the physical length of the rod. In SR th=
e
> observer will predict that the light path length of a moving rod is L/gamm=
a.

Actually, according to the definition above, if it is right, this
formula is wrong.

> In IRT the observer will predict that the light path length of a moving ro=
d
> is L/gamma or L*gamma.
>
> Ken Seto
>
>
>
>
>
>
>
> > The math for the above concepts are as follows:
> > L =3D the light path length of the pole at rest in the barn frame.
> > L' =3D the light path length of the pole moving wrt the barn frame.
> > L' =3D L/gamma
>
> > The above concept is included in a new theory of relativity called IRT.
> IRT
> > includes SRT as a subset. However, the equations of IRT are valid in all=

> > environments, including gravity. A description of IRT is available in th=
e
> > following link:/kn_seto/
> > Also visit my website:/kn_seto/
>
> > Ken Seto- Hide quoted text -
>
> - Show quoted text -