Re: SR cannot determine Contraction

"Dono" <sa_ge@xxxxxxxxxxx> wrote in message news:1a81e1c1-496a-496e-8714-e0f5451d5587@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Mar 3, 7:24 am, Tom Roberts <tjroberts...@xxxxxxxxxxxxx> wrote:
Dono wrote:
> All your explanations contain the built in assumption that length
> contraction is a physical process that allows rigid objects to
> contract stress-free

This is plain not true. The length contraction is a GEOMETRICAL
PROJECTION that makes the MEASURED length of the pole be shorter than
its proper length.

....which is exactly what I was telling you all along.

Its what we've been trying to tell you, and you have denied

there is no "compression" at all, just GEOMETRICAL
PROJECTION. It ought to be clear that merely LOOKING at the pole in a
different manner cannot possibly induce stress in the pole.

Perfect. Where we disagree is that the pole could be trapped inside
the barn with both doors closed.

And that is where you are wrong. You are taking a different position from what SR says, and so what you say cannot be a prediction of SR (which is what is being discussed . .what does SR predict will happen in (for example) the pole and barn 'paradox'

> I am telling you that the "contraction" you are talking
> about is also due to acceleration.
Nope. If this were true, how could the pole-frame observer see the
(short) barn going past the (normal length) pole with both doors open?
An interesting question,for the n-th I am not denying length
contraction,

Yes .. you are

I am questioning how it will account for fitting a larger
object inside a smaller closed box.

Well derr .. if the length is contracted, then it is not as long as it was, and is shorter than the barn and so it fits.

As an aside, the pole frame is not
problematic at all since both doors are open.

Eh? If the doors close in the barn frame, they close in the pole frame .. it's the same two events (front door closing, back door closing) in two different frames .. You cannot claim that the events do not happen in the pole frame if they happen in the barn frame.

Another approach showing this is wrong: Construct the pole out of
individual atoms in the pole frame, so it is NEVER accelerated. The
pole-frame observer knows the atoms are not "compressed" because they
measure the same sizes as in standard reference books. SR still predicts
the pole fits in the barn (in the barn frame).
This is where we diverge. Such a prediction is unphysical.

No .. it is not unphysical (in the sense that it has no physical effect as to what happens in the barn frame .. ie the pole fitting inside the barn). It is unphysical wrt the pole frame as the pole is not moving in the pole frame and so nothing happens to the pole in the pole frame.

> Torretti writes : "Relative motion will NOT make a solid body SHORTER"
Right. Relative motion has no effect whatsoever ON THE BODY.

Ah, but this is not what he means. If you read the whole paragraph

Please quote it

you
can see that he means that relative uniform motion does not ffect
objects the same way as heat/cold dilates/compresses rigid objects,

That's right

i.e. it will not make a larger object fit inside a smaller box.

That's wrong

> This clearly contradicts what you are saying.
Nope. I am discussing MEASUREMENTS OF THE POLE'S LENGTH FROM THE BARN
FRAME (and equivalent). Not any change IN THE POLE.

But you NEED a change in the pole in order to make it fit inside the
smaller barn.

NO ... gees you are stubborn

You are of the opinion that the geometric Lorentz contraction is
sufficient, I am questioning your assumption. Absent an actual
experiment, we have no way of settling this.

This is about the prediction .. not the reality. You disagreeing with the prediction of SR means you are disagreeing with SR itself. An experiment won't really help you.

This is getting overly repetitive -- don't expect me to continue until
you actually learn something.
Tom Roberts
Abusive AND condescending. This is how you react when you loose an
argument. Very scientific!

You can't talk .. you were the first to get abusive .. calling me a clown and a bozo for daring to point out that you were wrong and explaining why. You are a total hypocrite.



.

Relevant Pages

  • Re: TOM ROBERTS - Dono is confused, please help him out (was SR cannot determine Contraction)
    ... that there are some indirect results that support length contraction. ... He says the pole and barn thought ... "Uniform relative motion cannot make a longer object fit inside ...
    (sci.physics.relativity)
  • Re: SR cannot determine Contraction
    ... The length contraction is a GEOMETRICAL ... PROJECTION that makes the MEASURED length of the pole be shorter than ... the barn with both doors closed. ... individual atoms in the pole frame, ...
    (sci.physics.relativity)
  • Re: Dono not honest enough to admit his mistake?
    ... stuffed up what SR predicts happens wrt length contraction. ... A physically longer pole will not fit into ... toward the barn. ... "Uniform relative motion cannot make a longer object fit inside ...
    (sci.physics.relativity)
  • Re: SR cannot determine Contraction
    ... then synchronizing the clocks. ... In the frame in which the barn and the ... contraction of the rod. ... have trapped the pole inside the barn. ...
    (sci.physics.relativity)
  • Re: SR cannot determine Contraction
    ... -This is why one can't close the doors simultaneously in the barn ... frame without hitting the pole. ... very poor illustration for length contraction. ... -This is why, to date, we have no experimental test for length ...
    (sci.physics.relativity)
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