How long would it take to move a pole one light year long one foot?

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Discussion Overview

The discussion revolves around the hypothetical scenario of moving a pole one light year long by one foot and the implications of such an action on the transmission of force along the pole. Participants explore the nature of rigidity, the speed of sound in materials, and the propagation of forces at a molecular level.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the feasibility of a pole one light year long and suggests that the impulse would travel at the speed of sound in the material, providing an example with steel and calculating a time of 6700 years for the impulse to reach the other end.
  • Another participant argues that the movement would be instantaneous if considering a rigid body system, but acknowledges the implications of faster-than-light communication and the need for molecular interactions.
  • A different participant counters the instantaneous claim by emphasizing that force must be transmitted through molecular interactions, stating that if forces propagated instantaneously, sound would not exist as it relies on oscillation.
  • There is a mention of gravity propagating at the speed of light, suggesting a distinction between different types of forces.

Areas of Agreement / Disagreement

Participants express disagreement regarding the nature of force transmission along the pole, with some asserting that it would take a significant amount of time while others propose instantaneous transmission under certain conditions. The discussion remains unresolved as differing viewpoints persist.

Contextual Notes

Participants have not reached a consensus on the assumptions regarding the rigidity of the pole, the nature of force transmission, and the implications of molecular interactions. The discussion includes various interpretations of how forces propagate through materials.

Bender711
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A pole one light year long...

laying in bed last night I had this question pop into my pointy little head.

If I had a pole one light year long sitting between points A and B and I pushed it forward one foot from point A toward point B how long would it take to move at point B?


I've got an answer, but I'll wait to see what the people smarter than me have to say.
 
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That's a meaningless answer, funker, since no such thing exists.

Bender, it the impulse would travel at the speed of sound in that material. For example, if the pole were steel, with a speed of sound of 4500m/s, it would take 6700 years for the impulse to reach the other end of the pole.
 
FUNKER said:
it would be instantaneous, provided a rigid body system

Err, please don't answer like that. You are proposing faster than light communication here. If it were instantaneous, then we could send morse (poking) instantaneously, whereas light would take one year. If you hit one end of stick with a hammer, would the other end hear it instantaneously? No. You must think of the interaction at a molecular level.

EDIT: Russ beat me to it.
 
Huh? No, minijumbuk. You are simply wrong. Force has to be transmitted via molecular interactions. If forces propagated instantaneously, there'd be no sound because objects wouldn't oscillate. Striking a large bell with a hammer would just make it swing back and forth.

Gravity is different, but it still propagates at the speed of light.
 
I have deleted some blatentely incorrect posts.

Locking since the question has been answered and there is no point in further discussion.
 

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