The Lightyear-long Pole

  • Thread starter wolf_359
  • Start date
  • #1
3
0
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?
 

Answers and Replies

  • #2
phinds
Science Advisor
Insights Author
Gold Member
16,740
7,427
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.
 
  • #3
Nugatory
Mentor
13,246
6,128
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 [Broken]
 
Last edited by a moderator:
  • #4
3
0
The existance 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.
 
  • #5
phinds
Science Advisor
Insights Author
Gold Member
16,740
7,427
The existance 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?
 
  • #6
Drakkith
Staff Emeritus
Science Advisor
21,105
4,934
The existance 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.
 
  • #7
phinds
Science Advisor
Insights Author
Gold Member
16,740
7,427
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:
 
  • #8
Drakkith
Staff Emeritus
Science Advisor
21,105
4,934
Why is that something to be sorry about? I rather like it that way. :smile:
Oh, you... :rolleyes:
 
  • #9
Dale
Mentor
Insights Author
2020 Award
30,859
7,461
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.
 
Last edited:

Related Threads on The Lightyear-long Pole

Replies
3
Views
632
  • Last Post
Replies
7
Views
3K
  • Last Post
Replies
9
Views
676
Replies
7
Views
1K
  • Last Post
Replies
1
Views
475
  • Last Post
Replies
9
Views
2K
Replies
4
Views
3K
  • Last Post
3
Replies
66
Views
4K
Replies
6
Views
604
Replies
4
Views
4K
Top