Re: SR cannot determine Contraction

"Dono" <sa_ge@xxxxxxxxxxx> wrote in message news:3003240a-8c4b-4a93-a477-8f28e1122a6d@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Feb 26, 8:06 pm, Tom Roberts <tjroberts...@xxxxxxxxxxxxx> wrote:


As I have said before, IMHO the pole and barn gedanken is best
understood as displaying the relativity of simultaneity, rather than
length contraction.

Tom Roberts

Yes, we agree on this.
For example, there is a much better alternative to the Purcell
explanation than the one in the FAQ (http://www.edu-observatory.org/
physics-faq/Relativity/SR/experiments.html#Length_Contraction).
It is indeed based on the realtivity of simultaneity. See here:
http://chip-architect.com/physics/Magnetism_from_ElectroStatics_and_SR.pdf.
The author goes out of his way to point out "the correct derivation
based on non-simultaneity".

Indeed, the apparent paradoxical predictions of the pole-and-barn (ie that the barn is shorter than the pole and the pole is shorter than the barn), is resolved through understanding relativity of simultaneity.

Of course, you do also have to understand that the pole really *is* shorter than the barn in the barn frame of reference, and the barn is shorter than the pole in the pole frame of reference (where shorter means less length, and length means the distance between one and and the other simultaneously at a given point in time).

And yes, even the "pole in the barn paradox" looks much more credible
when explained from the PoV of the pole frame.

Indeed .. understanding the physics involved more completely always does help.

And yes, even MMX is a lot less hokey when explained "sans" length
contraction, in the frame of the lab (actually you did this very well
on this exact forum :-) ).

It is nice to be able to have a good discussion, probing a little
deeper the relativistic effects. Thank you !

So, are you now ready to admit that you were incorrect in your claims about the pole-and-barn (and length contraction in general), and that the pole really does fit inside the barn because its length in the barn frame is shorter?


.

Relevant Pages

  • Re: SR cannot determine Contraction
    ... Your phrase "makes objects shorter" implies a change to the ... but observations made from another frame cannot possibly affect ... barn frame, the pole becomes magically shorter, by virtue of relative ... That's completely irrelevant -- no measurement does that. ...
    (sci.physics.relativity)
  • Re: Pole and Barn for Dummies
    ... -- except for a brief discussion on how to tell which frame has the ... The reader bored with the Pole and Bar "Paradox" may wish to read ... The Pole and Barn question: ... back door, fixed to the earth. ...
    (sci.physics.relativity)
  • Re: Pole and Barn for Dummies
    ... -- except for a brief discussion on how to tell which frame has the ... The reader bored with the Pole and Bar "Paradox" may wish to read ... The Pole and Barn question: ... back door, fixed to the earth. ...
    (sci.physics.relativity)
  • Re: Pole and Barn for Dummies
    ... -- except for a brief discussion on how to tell which frame has the ... The reader bored with the Pole and Bar "Paradox" may wish to read ... The Pole and Barn question: ... back door, fixed to the earth. ...
    (sci.physics.relativity)
  • Re: Pole and Barn for Dummies
    ... -- except for a brief discussion on how to tell which frame has the ... The reader bored with the Pole and Bar "Paradox" may wish to read ... The Pole and Barn question: ... back door, fixed to the earth. ...
    (sci.physics.relativity)
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