Is the Lightyear Pole Paradox a Violation of Physics?

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Discussion Overview

The discussion revolves around a hypothetical scenario involving a rigid pole that is one light year in length, examining whether the other end of the pole moves simultaneously when one end is pulled. The scope includes theoretical implications and the properties of such an object if it were to exist, engaging with concepts of rigidity and the transmission of force in materials.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants argue that a rigid pole of such length cannot exist, as any disturbance would propagate at the speed of sound in the material, not instantaneously.
  • Others emphasize that the discussion is not about the existence of the pole but rather about the properties it would have if it could exist.
  • A participant suggests that using the laws of physics to analyze an object that contradicts those laws is inherently speculative.
  • Some express frustration with the hypothetical nature of the question, suggesting it breaks known laws of physics.
  • There are comments indicating a preference for discussions grounded in real physics rather than "what if" scenarios.

Areas of Agreement / Disagreement

Participants generally disagree on the validity of discussing the hypothetical pole, with some asserting that it leads to speculative reasoning while others are open to exploring the implications of such a scenario.

Contextual Notes

The discussion highlights limitations in applying physical laws to hypothetical constructs that do not conform to established principles, leading to unresolved questions about the nature of rigidity and force transmission in materials.

wolf_359
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Here is a question I posed to my Facebook friends this morning while waiting on my ride to work. I thought about the answer to it myself and got a good brain workout from it!

I would like to know your thoughts:

You have a rigid pole that cannot bend or stretch or otherwise deform in any way.
The pole is exactly one light year in length.
You pull on one end of the pole and it moves one meter.
Does the other end move the same distance at the same time? Why or why not?
 
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There is no such pole nor will there ever be. Matter does not work like that. Your disturbance at one end of the pole will travel through the pole at the speed of sound in the pole.
 
wolf_359 said:
Here is a question I posed to my Facebook friends this morning while waiting on my ride to work. I thought about the answer to it myself and got a good brain workout from it!

I would like to know your thoughts:

You have a rigid pole that cannot bend or stretch or otherwise deform in any way.
The pole is exactly one light year in length.
You pull on one end of the pole and it moves one meter.
Does the other end move the same distance at the same time? Why or why not?

There's an entry in the FAQ at the top of this page: https://www.physicsforums.com/showthread.php?t=536289
 
Last edited by a moderator:
The existence of the pole is not in question. The properties of such a pole if it were to exist is the question. It is also a subliminal attempt to cause you to think... But if this is too much for you, try an easier problem.

Thanks.
 
wolf_359 said:
The existence of the pole is not in question. The properties of such a pole if it were to exist is the question. It is also a subliminal attempt to cause you to think... But if this is too much for you, try an easier problem.

Thanks.

If unicorns existed, would their horns be more than a foot long?
 
wolf_359 said:
The existence of the pole is not in question. The properties of such a pole if it were to exist is the question. It is also a subliminal attempt to cause you to think... But if this is too much for you, try an easier problem.

Thanks.

I'm sorry, we talk about real physics here, not "what if" questions that break the known laws of the universe.
 
Drakkith said:
I'm sorry, we talk about real physics here, not "what if" questions that break the known laws of the universe.

Why is that something to be sorry about? I rather like it that way. :smile:
 
phinds said:
Why is that something to be sorry about? I rather like it that way. :smile:

Oh, you... :rolleyes:
 
We obviously cannot use the laws of physics to determine the properties of an object that the laws of physics forbids in the first place (ex falso quodlibet). Therefore, anything other than a discussion of why the laws of physics forbid it is speculative.

Since the OP is clearly not interested in such a discussion, this thread is closed.
 
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