Would pole or rope movement between two stars exceed the speed of light?

Question

Had this idea when I was 9 years old.. now 35! Physics teacher just said nothing could go faster than light and that was it -well I'd like an answer a little better than that.
If there was a taut rope or long pole between two stars, and (somehow) I managed to pull on one end, would someone on the other star, say 3 light years away, feel it pull at the same time? Or would they have to wait a few years??
If they do feel it at the same time, then surely pole movement (not as in lap dancing) has travelled faster than the speed of light, opening up super fast pole communication! If they don't feel it at the same time, then why's that?? Obviously I'm assuming that no alien cuts through the rope or pole, the stars don't move away from each other, and the person on the other Star has a great space suit to keep him alive whlst the experiment is being carried out!!! Please answer as soon as possible because my pole is already 3 metres long and only have 28×10 (power of 15) meters to go!

Answer 1

Actually, the inverse argument of your proposition was used in an extra credit question on an examination I took for a mechanical engineering course in college:

"Using the special theory of relativity, show that no material can have an infinite rigidity"

Answer: If a material of infinite rigidity existed, you could send signals along it at greater than the speed of light, a prohibition of the special theory of relativity..........

The most rigid stuff we know about has a wave propagation speed of only a few thousand meters/sec, a long way from 300 million m/s value of c.

Answer 2

No signal can travel faster than the speed of light (neglecting tachyons, which have never been observed in the real world, but in theory can never slow down to or travel BELOW the speed of light).

The ropes and poles would flex as the signal traveled along them. Since they would not move instantaneously, the signal would travel at a speed well below c.

Here's a variation on the pole idea. Suppose you have two very long poles crossed at an angle. The poles are rotating from their crossed orientation to become more parallel. The point P where the poles cross will travel down the poles as they approach parallel, moving faster and faster. Can the motion of P exceed the speed of light?

Yes it can! P does not have any physical manifestation and therefore no mass; therefore its motion is not limited by relativity. However, if P did have mass -- for example, if there was a ring around the crossing point -- then the poles would be forced to flex as the relativistically increasing mass drew more and more energy from them.

* To Michael below: Einstein's Special Theory of Relativity states that it would consume an infinite amount of energy to accelerate any particle with mass to the speed of light. So it's impossible to accelerate even an electron to the speed of light, although scientists can get very very close now. Photons have no mass so they travel at the speed of light and ONLY at the speed of light (which explains why everyone measures the same value for c). Tachyons have an 'imaginary' mass (a multiple of the square root of -1) and so they cannot travel as slow or slower than light... only faster!

Answer 3

As "Steve" stated, an infinitely rigid object does not exist and therefore what you are describing is impossible.

When you pull/push on an object in the real world, the object does not immediately respond to the force, rather it expands/compresses every so slightly in an elastic fashion (like a spring). When you push on one side of a box, for example, the force must be transmitted over to the opposite side first in order to get those atoms to move, which can then be followed by atoms nearer and nearer to the side of the box the force was applied to. The more and more rigid an object you push on, the less it compresses and the quicker the response time. It would take an object of infinite rigidity (totally incompressible) in order to get an immediate response from a pull/push.

So in your example of a very long pole (3 ly long), if someone push on the one side of the pole, it would take 3 years, minimum (assuming the "push" traveled at the speed of light) for someone on the opposite side of the pole to feel it.

Answer 4

When you pull on a rope or push on a pole, you are using it's elasticity to transmit energy from one point to another. It may seem as though there is no extension or contraction but there is and it is passed from the end where the force is applied from molecule to molecule along the rope or pole.

I doubt very much that energy transmitted in that way could exceed the speed of light since what you are talking of is a wave of extension/contraction passing down the connection.

If you concentrate on the supposed sympathy between objects which Einstein is supposed to have called 'spooky action' (Google for the Einstein-Podolsky-Rosen paradox and Quantum Mechanics), I think you might have better chance than with a rope.

(Errr ... where are you going to stand to twist a rope that long, anyway, and won't it take you several light years to get the twist from one end to another?)

Answer 5

NO, as you start the pull it would not generate enough pull
to move the rope, the pull would end as soon as you pulled.
Nothing on this earth could do it either. Do questions that
is in your realm of reality, then we can all learn from each
other And keep your pole satisfied. C Ray

Answer 6

No, a mechanical impulse in a solid medium will travel at the speed of sound for that medium. This is why the transcontinental string telephone never caught on.

Answer 7

The way that I understand Dr Einsteins theory is that he didn't say exactly that nothing could exceed the speed of light but that it would be irreversibly changed if it did and he didn't say how. Am I wrong?

Answer 8

nothing can go faster than light due to e=mc^2. (c=speed of light). becasue the speed of light is a constant, its basically saying that the energy of an object is directly proportional to its mass. (as the energy gets bigger, the mass gets smaller).so if something were to go faster than light the energy required would be infinite, and thats why it's impossible to go faster than the speed of light

Answer 9

woahhhh ur brainy!!

i couldnt have thought of something like that now (at the age ov 17) let alone at the age of 9 !!

i think you should go ahead and try it... n i wish u the best of luck..

but i was jus thinking.. how can u stand on a star when a star is just a ball of burning gas??

X

Answer 10

I like the way you think, certainly some room for thought there.