Super Slo Mo Slinky Demonstrates Why a Pole Push Won't Go Faster Than Light.

At one time when contemplating time travel and the effects of light speed on matter, came up with as most do when thinking about this kind of thing, the light-year long pole hypothesis.

The postulation goes something like this.

If you were to build a pole of immense strength, of the most densest of materials you could make an object from. Then if you were to make this pole very very long, say from here to say one light year away.
What would happen if you pushed one end of the pole, in your mind’s eye the other end of the pole would also move as you pushed, this way you could send information faster than light….

WRONG….

The reason this doesn’t work is due to the fact that information in the traditional sense does not travel faster than light. So when you push at one end of the pole, the information has to travel down the pole and you get something called a compression wave down the pole, if you like when you push the pole what you are doing is sending a wave down the pole to the other end.

The following you tube clip using a slinky demonstrates this very very well. Notice how the slinky appears to be completely stationary at the end with nothing to keep it up…. That is because it has not yet received the information that it is falling.



I hope you have enjoyed this clip and also learned something new from this thread.

All the best,

Korg.

I like it. And a very good job at explaining something that's difficult to fathom. (for me anyways)
star/flag!

reply to post by Korg Trinity


Hmmm, if you push one one end of a pole a lightyear long, would the energy you put into it just be absorbed by the pole and never reach the other end?

I'm thinking shock absorbers on a car. You hit a pothole, the shock absorbers take in this energy, and then where does that energy go from there?

Originally posted by jiggerj
reply to post by Korg Trinity

 

Hmmm, if you push one one end of a pole a lightyear long, would the energy you put into it just be absorbed by the pole and never reach the other end?

I'm thinking shock absorbers on a car. You hit a pothole, the shock absorbers take in this energy, and then where does that energy go from there?

"for every action there is always an equal and opposite reaction" - Newtons Law of Motion.

In the case of the shock absorber, what you have is a cushioning effect, but the actual energy is stored in the spring, then released once more. The energy is not absorbed, just redirected.



Korg.

The following you tube clip using a slinky demonstrates this very very well. Notice how the slinky appears to be completely stationary at the end with nothing to keep it up…. That is because it has not yet received the information that it is falling.

but im not sold on it completely at this point. To me it seems the spring is falling its just that it is compressing at exactly the same rate which gives just one end the illusion that it is standing still.

The top part of the spring would actually be accelerating down faster than the speed that gravity would make it travel. This would be at an acceleration exactly equal to the upwards compressing the bottom part of the spring would be undergoing.

Originally posted by PhoenixOD

The following you tube clip using a slinky demonstrates this very very well. Notice how the slinky appears to be completely stationary at the end with nothing to keep it up…. That is because it has not yet received the information that it is falling.

Very interesting but im not sold on it completely at this point. To me it seems the spring is falling its just that it is compressing at exactly the same rate which gives just one end the illusion that it is standing still.

The top part of the spring would actually be accelerating down faster than the speed that gravity would make it travel. This would be at an acceleration exactly equal to the upwards compressing the bottom part of the spring would be undergoing.

edit on 31-3-2013 by PhoenixOD because: (no reason given)

Not Sold?? LoL I'm not selling anything.

Watch the video again and notice that the bottom is at rest. There is no movement at all. But if you are still not convinced then there was a follow up video, if you watch it to the end then you will see that gravity is taken out of the equation and the experiment is done horizontally on a table top.



Hope this helps,

Korg.

reply to post by Korg Trinity


Very interesting, first i thought you might be wrong in your explanation and now i think i just didn't understand what you were trying to say.

Im pretty sure there's more than one action happening here. If you replicate the whole thing with a peice of string the whole bit of string falls almost instantly so there is some upwards compression going on with the spring. I need to spend more time thinking about this to fully get my head round it. Its late here

The bigger question is : Why do i always stumble into these threads 10 mins before im about to go to bed??!

S&F for a pre-bed mind f**k

The model of a mechanical spring operating in a 1g and 1d framework cannot duplicate the quantum world.

reply to post by Korg Trinity

In the case of the shock absorber, what you have is a cushioning effect, but the actual energy is stored in the spring, then released once more. The energy is not absorbed, just redirected.

Redirected to where? (You had to know I'd ask this. lol)

Originally posted by Korg Trinity

Originally posted by jiggerj
reply to post by Korg Trinity

 

Hmmm, if you push one one end of a pole a lightyear long, would the energy you put into it just be absorbed by the pole and never reach the other end?

I'm thinking shock absorbers on a car. You hit a pothole, the shock absorbers take in this energy, and then where does that energy go from there?

"for every action there is always an equal and opposite reaction" - Newtons Law of Motion.

In the case of the shock absorber, what you have is a cushioning effect, but the actual energy is stored in the spring, then released once more. The energy is not absorbed, just redirected.

Korg.

The springs are there to balance the weight of the vehicle against the force of gravity, and little more. Progressive-rate springs can create additional resistance to compression as they are compressed further but similarly exhibit less resistance to compression as they extend.

The shock absorber is intended to slow the motion of the suspension and vehicle in relation to each other and does exactly what its name implies- absorbs shock, or motion. It acts in two directions: compression and extension, a.k.a. jounce and rebound in suspension parlance. During either state, hydraulic fluid and valving within the shock work together to create friction which thus dampens motion. The heat generated by this friction is radiated into the atmosphere.

Originally posted by PhoenixOD
reply to post by Korg Trinity

 

The compression of the spring happens faster than the time it takes for the object to be effected by gravity. The bottom does not move because its a spring and gravity is acting as a kind of anchor to the bottom end.

The bigger question is : Why do i always stumble into these threads 10 mins before im about to go to bed??!

S&F for a pre-bed mind f**k

edit on 31-3-2013 by PhoenixOD because: (no reason given)

LoL I hate sleep anyway... little slices of death.

I understand that you think that the reaction is faster than gravity, but what I am trying to demonstrate is that if that slinky was in space, and you were to create a wave by pushing on one end then other end won't move until the wave reaches it. This is also true of all matter in varying degrees.

Therefore if you had a way to make a one light year long pole, and pushed one end, the other end wouldn't move until the compression wave reached it... in this case just a little longer than one year depending on the density of the material used.

The following clip is a good example of how the movement would propagate at the atomic level.





Korg.

reply to post by Korg Trinity

Therefore if you had a way to make a one light year long pole, and pushed one end, the other end wouldn't move until the compression wave reached it... in this case just a little longer than one year depending on the density of the material used.

I totally agree with that

LoL I hate sleep anyway... little slices of death

and i have been trying to get out of that way of thinking for years

Originally posted by jiggerj
reply to post by Korg Trinity

 

In the case of the shock absorber, what you have is a cushioning effect, but the actual energy is stored in the spring, then released once more. The energy is not absorbed, just redirected.

Redirected to where? (You had to know I'd ask this. lol)

Sorry to appear abrupt but obviously downwards when the pressure of the upward force has been released.

here is another you tube explaining stored energy in a spring.



Simply put, the force applied to the spring is stored as elastic potential energy. For further learning about this you need to learn about Hook's Law.



Korg.

Originally posted by abecedarian

Originally posted by Korg Trinity

Originally posted by jiggerj
reply to post by Korg Trinity

 

Hmmm, if you push one one end of a pole a lightyear long, would the energy you put into it just be absorbed by the pole and never reach the other end?

I'm thinking shock absorbers on a car. You hit a pothole, the shock absorbers take in this energy, and then where does that energy go from there?

"for every action there is always an equal and opposite reaction" - Newtons Law of Motion.

In the case of the shock absorber, what you have is a cushioning effect, but the actual energy is stored in the spring, then released once more. The energy is not absorbed, just redirected.

Korg.

The springs are there to balance the weight of the vehicle against the force of gravity, and little more. Progressive-rate springs can create additional resistance to compression as they are compressed further but similarly exhibit less resistance to compression as they extend.

The shock absorber is intended to slow the motion of the suspension and vehicle in relation to each other and does exactly what its name implies- absorbs shock, or motion. It acts in two directions: compression and extension, a.k.a. jounce and rebound in suspension parlance. During either state, hydraulic fluid and valving within the shock work together to create friction which thus dampens motion. The heat generated by this friction is radiated into the atmosphere.

edit on 3/31/2013 by abecedarian because: (no reason given)

An excellent explanation, and one I couldn't give, as I am not a mechanic

Korg.

There are two forces at work. The bottom of the slinky is held in place by the top of the slinky. When you release the top, the bottom is still held by the 'springiness' of the rest. As the top falls it releases the 'springiness is elasticity) as it falls.

An infinitely dense pole would have no elasticity and thus may move instantly in you example.

P

reply to post by Korg Trinity


Not only that but ANY neural network has to process the initiation of an action using a network of nerves.

We are all bound, apparently, to this speed limit.

I don't know who would care about such a silly proposition as an endless pole.
Let's forget impossible poles that get invented to discuss the limits of the speed of light and mass according to old physics.

My signature line says it all, if cryptically. but you gotta think on your own there.

It you negate mass in an object, then the stuff about SOL limits, infinite mass at velocity, etc. becomes moot. All of that confining physics is side-stepped and can be ignored because it is totally non-relevant, outside of the physics where no one seems to want to go.

The simple step of imagining a null mass state is not that hard to understand, nor is the actual acceptance of the phenomena called UFOs, but scientists, governments and ordinary people can't allow themselves to think along those lines. But of course, the government and the scientists have their own reasons of denial and do utilize that stuff because we see it evident in every UFO that ever visited Earth and they now use our versions in the triangles that only a fool would ignore. As for the general public, they can't think beyond where they left the TV remote (if older) or what next app they want to download (if younger).

It is simply, absolutely silly that we keep hearing about the limits of velocity as measured by standard, everyday physics when nothing about it applies if you can negate mass. Now is that so hard to understand?

Careful, to allow null mass, you must automatically allow that UFOs actually exist and probably are here from such incredible distances away that you must also throw away terms like "light-years" that also become--can I say it-- relatively irrelevant.

reply to post by Korg Trinity

Therefore if you had a way to make a one light year long pole, and pushed one end, the other end wouldn't move until the compression wave reached it... in this case just a little longer than one year depending on the density of the material used.

That would only happen if the pole had mass. A good way to think of this is to imagine the opposite scenario; pulling on the pole. That would create a "tension wave" in the same way, because of the inertial forces caused due to the mass of the pole. A massless pole would get around that problem... dunno if such a thing is possible though.

Another interesting thought is what would happen if you built a simple closed circuit which had super long wires. Connecting some sort of electrical potential (battery) to the circuit would create an electric current (flowing electrons). The free electrons in the wire are pushed by the voltage, they don't come from the battery.

I like to picture it as a tube full of marbles. If you push another marble into the tube all the marbles move forward to make room for the next one, so it's essentially an instantaneous effect when you switch on a light bulb. Obviously the same sort of compression wave solution would apply to the marbles, but what about electrons?

Would there actually be some sort of wave which caused the electrons at the end of the wire to react later then the electrons at the beginning of the wire? Or would all the electrons begin moving at the same time? Keep in mind electrons are quantum objects... I'm not exactly sure what the answer to this would be but it's much more complex than marbles.

Originally posted by pheonix358
There are two forces at work. The bottom of the slinky is held in place by the top of the slinky. When you release the top, the bottom is still held by the 'springiness' of the rest. As the top falls it releases the 'springiness is elasticity) as it falls.

An infinitely dense pole would have no elasticity and thus may move instantly in you example.

P

Actually, the denser the material the more atoms there are and there fore the wave takes longer to propergate. The process would be the same regardless of mass. I think it's also worth mentioning that your point about infinite density would cause an event horizon ,'a black hole'. And then all bets are off.

Peace,

Korg

reply to post by ChaoticOrder


I think its actually exactly like the marbles in the tube.

Every metal wire is technically a tube of electrons pre filled. When you put one extra in one end, one pops out the other, but not 'the same electron'. The wave is the first electron moving to the next atom and the electron knocked off the atom goes to the next one and so on till it gets to the end after many many electrons have swapped to the next atom. The speed of the wave, i would guess is some where in the neighborhood of the speed of light.

The only thing which might be able to travel faster than the speed of light, would be changing a gravity field - would that be instantly detected a light year away or not?

Lets say i have a marble and i can measure its gravity from one light year away. Then a switch is pressed and the marble now has the gravity of the sun, would it take one year for the effect of the gravity to reach my detector?