Accelerated Triangle and Length Contraction

In summary, Neil and Michael visit a solid not revolving planet and attach a jet engine to it in order to make it turn around its axis. Two dots are placed (1 meter apart) in line with the engines thrust: pointing out the east-west-leg. A third dot is placed 1 meter north of the first dot, together pointing out the north-south-leg. So the isosceles triangle fits perfectly between the three dots. Then they start the engine, Neil remains on the planet and Michael boards the spaceship to watch the accelerating planet from a stationary place above the surface of the planet. After a while, when the planet has reached a constant revolving speed, Neil checks whether the dots on the surface of the planet
  • #36
metastable said:
Suppose the planet is an oblate spheroid such that when it rotates it becomes a sphere through centrifugal forces

An object that is oblate before it starts rotating will get more oblate as it rotates, not less.

More generally, I don't see the point of piling on complications to the scenario, since all they do is distract and obfuscate the primary issues that the OP was raising.
 
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  • #37
Yes, thank you I corrected it to prolate.
 
  • #38
PeterDonis said:
As the scenario is presented in the OP, it is inconsistent. The OP claims that Neil will see the triangle still match the dots, which implies that the triangle must stretch. But it also claims that Michael will see the triangle length contracted, which implies that the triangle does not stretch.

Either choice would be consistent by itself; but only one of the two can be true of a single scenario.
The triangle is specified to be loose. So, to my mind, the OP is describing the scenario where the triangle does not stretch and incorrectly describing Neil's observations.

Possible I'm reading more into your writing than you intended, but it seemed to me you were entertaining the possibility that the loose triangle could stretch. I've been answering on the basis that it wouldn't, and still can't see a reason it would. But you've been known to correct my understanding on occasion...
 
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  • #39
PeterDonis said:
As the scenario is presented in the OP, it is inconsistent. The OP claims that Neil will see the triangle still match the dots, which implies that the triangle must stretch. But it also claims that Michael will see the triangle length contracted, which implies that the triangle does not stretch.
Actually I did not intent to “claim” the matching, but more assumed that it would match. From my previous question (Why is the null-result of M&M experiment considered as proof for RT) I learned (from Nugatory) that “the experiments are at rest relative to the apparatus, so they find no length contraction.”. Hence, I also assumed that the stretching of the dots would not take place in Neil’s perspective.
But as you try to tell me now, I should understand that here an influence of ‘higher’ order is involved.
 
  • #40
Ibix said:
it seemed to me you were entertaining the possibility that the loose triangle could stretch

No, I wasn't. If it is clearly specified that the triangle is loose, then it won't stretch and the description of what Neil will see in the OP is incorrect.
 
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  • #41
Foppe Hoekstra said:
But as you try to tell me now, I should understand that here an influence of ‘higher’ order is involved.
I wouldn't call it an influence of a higher order. It's just that there is an awful lot of mass bound together and undergoing ferocious acceleration, and you can't neglect the effects of that by using an inertial frame (or any other way). In the Michelson-Morley case nothing is accelerating so there are no forces distorting anything.
 

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