Length contraction: Is it permanent?

  • #26
Dale
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What acceleration profile is required by the far end of rod X (the end closer to point B) so that the distance between both ends of rod X remain constant in their proper frame?
Essentially, yes. So since the distance is constant in the proper frame (momentarily co moving inertial frame), once those frames are the same then the distances are the same by definition.
 
  • #27
Ibix
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Yes particles would carry an imprint of the past history of their motion, and yes the particles from the exploding nova would be shorter than the ones on earth but how would we know? The only way to observe it would be to go get some of those particles around that exploding nova and come back to earth to compare them to the one formed by radioactive decay here on earth!
The Sun, of course, is not a first generation star. Much of the solar system is reconstituted from bits that were parts of other stars that exploded. Wikipedia, for example, says "a high abundance of heavy elements in the Solar System, such as gold and uranium...could most plausibly have been produced by endothermic nuclear reactions during a supernova, or by transmutation through neutron absorption within a massive second-generation star." [my bold]. In other words, we'd see particles bearing the imprint of previous high speed movement right here on Earth. I'm not aware of us ever having done so (probably because the concept makes no sense, as phinds points out).

Length contraction is closely related to the observation that the cross-section of a cylinder looks like a circle when it is end-on to you and elliptical when it is off at an angle to you. It'll look like a circle again if you look at it end-on again. Expecting there to be after-effects from not looking at it end-on (unless you squashed it when you were rotating it - hence my first post) would be daft.
 
  • #28
Orodruin
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Yes particles would carry an imprint of the past history of their motion, and yes the particles from the exploding nova would be shorter than the ones on earth but how would we know? The only way to observe it would be to go get some of those particles around that exploding nova and come back to earth to compare them to the one formed by radioactive decay here on earth!
This really does not make any sense. Where do you think the heavier elements in the solar system have originated. And as I have told you repeatedly in this thread, length contraction is not about an object changing its physical properties, it is about how the object is perceived by different observers who are in relative motion.
 
  • #29
phinds
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... as I have told you repeatedly in this thread, length contraction is not about an object changing its physical properties, it is about how the object is perceived by different observers who are in relative motion.
I have also pointed this out several times. This thread is getting tedious.
 
  • #30
This really does not make any sense. Where do you think the heavier elements in the solar system have originated. And as I have told you repeatedly in this thread, length contraction is not about an object changing its physical properties, it is about how the object is perceived by different observers who are in relative motion.

Hey thanks for your answer.
I'm not looking to argue what the sun is made of, and trust me I'm not trying to prove that you guys or physicists in general are wrong. Please be patient with me because I take this thread very seriously(I've been ignoring my customers for the past couple days just to focus on my research), I do hope you guys can keep an open mind about things and not get upset just because I'm questioning what is believed by the community.
Like I said repeatedly before I understand that everybody believes that length contraction doesn't change the physical properties and that it is about perception, but did you guys just accept it because it's what has been said by scientists 50 years ago or did you research the proof? And please don't dodge the question with a vague answer about what we would observe because what humans can observe is limited.
As far as I know the physicists that asked the question about length contraction are Dewan, Beran and Bell in the Bell's spaceship paradox and it looks like they only arrived to their conclusions through deductions that don't cover all the angles.
Like I said before please don't feed me some generic answer or some previously said statement because that is irrelevant to me, if you can't give me a proof it's all good but just let me know so I don't keep looking for an answer that can't be verified.

Like Einstein said: "Common sense is what tells us the earth is flat"
 
  • #31
Ibix
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I'm not looking to argue what the sun is made of
Neither are we. We are just pointing out that everything around you is made up of a mix of matter that has travelled at relativistic speeds relative to its current state and matter that has not. Your idea would have physical consequences that we don't see. It's a non-starter I'm afraid.

Edit: not to mention, what does an observer co-moving with the moving rod see? According to Bob the rod accelerated from rest. According to this new observer the rod decelerated to rest. Should it be showing these after-effects of length contraction (because it has decelerated according to the new observer) or not (because it hasn't yet decelerated according to Bob)?

Like I said repeatedly before I understand that everybody believes that length contraction doesn't change the physical properties and that it is about perception, but did you guys just accept it because it's what has been said by scientists 50 years ago or did you research the proof?
Please see my previous paragraph. And my previous post. And the post by Orodruin that you quoted...
 
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  • #32
Orodruin
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Please be patient with me because I take this thread very seriously(I've been ignoring my customers for the past couple days just to focus on my research), I do hope you guys can keep an open mind about things and not get upset just because I'm questioning what is believed by the community.
There is an overwhelming amount of experimental evidence for the consequences of SR and GR. So much in fact that any description even attempting to build further must include them. This quoted text rings large warning bells to me as it seems to suggest you do not "believe" in the effects of relativity and therefore has started to work on your own theory. This is doomed to fail. The effects are well established experimental facts. Also note that Physics Forums, while encouraging asking questions to learn and understand, forbids the discussion of personal theories and speculation.

The original question has been answered several times over. I am therefore closing this thread.
 

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