Fundamental flaw in relativity? You can (possibly) disprove FTL limit sitting right at your desk.

Heya ATS

There was a chat going on sometime back, or a thread, that really got me thinking about just matter in general. The theory of relativity in regards to ftl travel is simple, nothing goes faster than the speed of light.

Can't find the thread, otherwise I would link it here..(hopefully some astute ats member will help in the search)


ok, the experiment to (potentially) show FTL information transfer. I suggest that not only will you be able to make information go faster than light, you will be able to make information go literally instantaniously from one point to another.

Grab a pencil (or whatever is close, long, and rigid). place it on the table. now, push one end.
Congratulations, you just disproved relativity (maybe).
Why? The tip of the pencil away from your finger is moving instantanously when you apply pressure to the other side. Not impressed yet? ok...now imagine that pencil was in space and a million miles long. Pressing it would produce the same result, it would push away, and the other side a million miles away would also move instantly.

How is this possible? atom presses against atom. the chain reaction goes all up to the other side of the pencil and it moves. instead of taking 5-7 seconds of reaction time, it would be done immediately.

I don't see how this experiment (the million mile "pencil") could be done effectively anytime soon, but perhaps we could confirm this through a shorter example and with super computers making sure that things move immediately.

If indeed its confirmed that things connected move instantly, what does this mean? Obviously, this won't change much in regards of new tech going on, but would it prove things like entanglement theory or perhaps note a new underlying force of nature we have yet to comprehend?

Thoughts? Debunking welcome.

reply to post by SaturnFX


Your pencil experiment is essentially quantum entanglement and I believe it has been proven that at least information can travel faster than light

Physicists spooked by faster-than-light information transfer

Link

Device Makes Radio Waves Travel Faster Than Light

Link

reply to post by SaturnFX


So... techically speaking, all you need is a big enough thump on the back end of a spaceship that is also somehow compressing the atoms ahead of, and maybe even behind itself, and bingo, instant travel. Amiright?

But, if you place the pencil on a huge floor, and push it, the problem is not that the tip moves just as fast as the back, but that it eventually stops, too. And how far it goes depends upon the push. And how fast it goes depends upon the push.

So I would think a million mile pencil would still take time to have the atoms compress and move to the tip, because where do you get something big enough to push a million mile pencil that hard and that fast?

Hm. I dunno...

It's an interesting idea. I've wondered if an instantaneous reaction to stimulus is FTL information transfer or just a consequence of the rigidity of the object? Does a solid object really move instantaneously when you push one end of it? I don't think the inertia provided by your finger to one end of the pencil transfers instantly to the other end of the pencil, though - the pencil is not perfectly rigid.

Like if you had a blob of mud, you poke one side and the forces all have to push sequentially molecules to the next position, but it takes a moment for that shockwave to travel through the mud. There is a still a shockwave in the pencil when you push on one end of it, its just that it travels faster because of the rigidity of the pencil. I think that makes sense? I think the pencil would have to be a single, perfectly rigid unit to imply FTL...

I'm gonna try to explain this idea I have in my head but I always have a hard time with it... Actually I just realized that what we are talking about here is the propagation velocity of energy waves. When you touch the pencil, you don't make physical contact with it - the atoms of your finger and the pencil are surrounded by electromagnetic force fields which interact. Finger forces push the pencil's atom's force-fields which in turn contain and therefore move the nuclei and the rest of the atoms. So the question is how fast do these electromagnetic forces propagate?

Sound propagates at the speed of sound, of course. Light, at the speed of light. There is a debate as to the velocity of gravity as well... If propagation velocity is infinite/instantaneous, then I think that it would indeed be FTL info/energy transfer. If your finger's atoms' forces push on the pencil, so long as all the force-field interactions occur in no time, it would be FTL.

However, if all energies propagated instantaneously, wouldn't the universe be long "over" by now?
Is it possible for something to happen instantly? Science says no, as far as I understand the concept of a Planck unit: en.wikipedia.org...

Rather, I should revise that statement to say that some advanced theories are thinking that space and time are "granular" and that there is a smallest possible unit of space and time. Thus there is no instantaneous anything.

Connecting this to a more esoteric set of ideas, I think perhaps what is referred to as "density" or "dimension", as in the 7 or more densities of consciousness/the universe (we are usually referred to as 3rd density/dimensional, and the next density or consciousness level is 4th, etc), refers to the density of what could be called "time quanta", the smallest unit of time possible in that density. For example, the Planck time is representative of our density/dimension by providing the smallest unit of time for our density. Higher densities/dimensions would have a smaller single unit of Planck time/length because more individual units of time/space fit into, for example, one second. Perhaps in this density, one second of time can be divided into 100 units. In the next, one second of time could be divided into 200 units, meaning more units/length of time meaning increased temporal density.

Hope that makes sense, lol, going a little far out for this one

reply to post by Libertygal


If everything is stuck together as one unit, then there is a singularity, and instantaneous travel/transfer is necessary, because there is nothing but everything. If that makes sense...

This is touched on in basic physics classes. There exists no perfectly rigid body. Due to the specificity of the sticks elasticity and density, the effect of hitting the stick propagates along the stick at no faster than the speed of light.

reply to post by SaturnFX


Very simple and interesting illustration via desktop experiment.

However the issue essentially is lets say your finger is the "information" or "mass" or whatever that you want moved from point A to point B. when you push the pencil your finger doesn't jump instantaneously to the tip of the pencil. So as far as movement of A to B this doesn't change much like you have said. However, it has some interesting implications if true. Such as how mass may interact with other mass millions of miles away instantaneously.

Although this is hard to take as the case with as much as going on in the entire universe it wouldn't be possible for there to be any form of stability. Essentially there would be no order as everything pushed on everything instantly across the entire expanse of the universe.

Nice question. I first think to get this kind of answer we need to move on from the rocket engine age and do some real spaceflight experiments.
What end of the million mile pencil will you be on? If you were sitting at the rear or back of the pencil, It would still take some time for you to get to the where point of the beginning(front) of the pencil. Unless it was thumped with a million mile a second of force. Then it would still take one second for you to get to the original postion of the front. If this makes any sense, I just woke up and need more time to ponder this question. Good question to make my head explode.

Originally posted by RestingInPieces
This is touched on in basic physics classes. There exists no perfectly rigid body. Due to the specificity of the sticks elasticity and density, the effect of hitting the stick propagates along the stick at no faster than the speed of light.

I took advanced physics classes.

Can you provide a source for this?

Also I'm not sure you understand what he's saying.

You can move the stick at a very slow speed. But if the stick is long enough information about the movement of the stick can reach the destination faster than light would get there. So say push the end of the stick 1 cm in 1 second and shine a flashlight at the same time as you start pushing the stick. Wouldn't the other end of the stick start moving before the light got there, if the stick is long enough?
(unless you can find a source that says otherwise).

I don't know of any part of relativity moving a long stick would violate, so I think it's an interesting thought experiment, but obviously a stick that long isn't very practical or realistic. But it's interesting nonetheless.

@saturnFX, the other thread you were looking for (I think) referred to moving a massive object faster than light, didn't it? and since the stick is moving slower than light, that wouldn't apply. It's not a mass that's moving faster than light in the thought experiment, it's only information about the movement of the stick. I can't think of an FTL violation with the long stick, but I'll think about it some more and post some additional thoughts if I have any.

What part of relativity do you think it violates, or why do you say "flaw in relativity"?

Good OP! It made me think!

Originally posted by Arbitrageur
What part of relativity do you think it violates, or why do you say "flaw in relativity"?

Basically, nothing can move faster than light, physical, data, etc.

now, taking the million mile pencil example, lets move it back and forth in a morse code style. person on the other end measures the other end and notes the moves, writing down the code.

the information (data) is transferred immediately from one end to another because the physical device moving at one end is also moving at the other end. this is data, physical objects moving, etc. interesting, and it flys in the face of relativity (if it is proven to work like that). So, distance doesn't matter then if this is how it works...be the pencil just 10 inches, or 10 million light years.

This can provide no actual technology edge...there will be no space ship that is run on pencil pushing power or anything..just a thought exercise to try and understand what is going on here that -may- uncover a new special rule for relativity that allows for this type of data transfer or something...(again, if it pans out).

I took some basic physics courses in university...nothing like this was hit on.

Isnt this basically speed of sound in a material? You push one end, and a mechanical wave of particles will spread at the speed of sound in the stick to other end. Much slower than the speed of light.

Also, you are in fact pushing on the stick with electromagnetic force, and the particles making up a stick are held together by EM forces, too. So even theoretically, such an interaction cannot spread faster than the speed of light.

OP, there is a topic about this already, check it out:

www.abovetopsecret.com...

Also, watch the beginning of this video about longitudinal waves:

Originally posted by Arbitrageur

Originally posted by RestingInPieces
This is touched on in basic physics classes. There exists no perfectly rigid body. Due to the specificity of the sticks elasticity and density, the effect of hitting the stick propagates along the stick at no faster than the speed of light.

I took advanced physics classes.

Can you provide a source for this?

Actually I found it myself:

Is Faster-Than-Light Travel or Communication Possible?

4. Rigid Bodies

If you have a long rigid stick and you hit one end, wouldn't the other end have to move immediately? Would this not provide a means of FTL communication?

Well, it would if there were such things as perfectly rigid bodies. In practice the effect of hitting one end of the stick propagates along it at the speed of sound in the material; this speed depends on the stick's elasticity and density. Relativity places an absolute limit on material rigidity in such a way that the speed of sound in the material will not be greater than c.

The same principle applies if you hold a long string or rod vertically in a gravitational field and let go of the top end. The point at which you let go will start to move immediately, but the lower end cannot move until the effect has propagated down the length at the speed of sound in the material.

It is difficult to formulate a general theory of elastic materials in relativity, but the general principle can be illustrated with newtonian mechanics. The equation for longitudinal motion in an ideal elastic body can be derived from Hooke's law. In terms of the mass per unit length p and Young's modulus of elasticity Y, the longitudinal displacement X satisfies a wave equation (see for example Goldstein's "Classical Mechanics"):

d2X d2X
p --- - Y --- = 0
dt2 dx2

Plane wave solutions travel at the speed of sound s where s2 = Y/p. This wave equation does not allow any causal effect to propagate faster than s. Relativity therefore imposes a limit on elasticity: Y < pc2. In practice, no known material comes anywhere near this limit. Note that even if the speed of sound is near c, the matter does not necessarily move at relativistic speeds. But how can we know that no material can possibly exceed this limit? The answer is that all materials are made of particles whose interaction are governed by the standard model of particle physics, and no influence faster than light can propagate in that model (see the section on Quantum Field Theory below).

So although there is no such thing as a rigid body, there is such a thing as rigid body motion; but this is another example in the same category as the shadows and light spots described above which do not give FTL communication. (See also the FAQ articles The Superluminal Scissors and The Rigid Rotating Disk in Relativity).

So according to that the stick isn't as rigid as we think it is and that's why it doesn't work.

The pencil seems fairly rigid when you push it so I guess it's hard to visualize how long it takes for the other end to move.

I wonder if these theoretical solutions have been tested in a lab?

Originally posted by Arbitrageur

Originally posted by RestingInPieces
This is touched on in basic physics classes. There exists no perfectly rigid body. Due to the specificity of the sticks elasticity and density, the effect of hitting the stick propagates along the stick at no faster than the speed of light.

I took advanced physics classes.

Can you provide a source for this?

Forgive me, but I don't audit college courses. You must have had some pretty bad teachers, or lazy students in your classes. My Physics 101 professor and even my astronomy prof talked about this.

Also I'm not sure you understand what he's saying.

I'm sure you're not.

You can move the stick at a very slow speed. But if the stick is long enough information about the movement of the stick can reach the destination faster than light would get there. So say push the end of the stick 1 cm in 1 second and shine a flashlight at the same time as you start pushing the stick. Wouldn't the other end of the stick start moving before the light got there, if the stick is long enough?
(unless you can find a source that says otherwise).

It wouldn't happen that way because the stick is not one single "thing". It's not perfectly rigid. The forces have to travel between atoms in the object. Think of it like a spring or a big slinky or rubber. When you move the bottom of the stick you initiate a wave of forces which travel through the stick and act upon it's constituent atoms.

All of the atoms, whose information propagation is bound by relativity and the speed of light, would have to be propagating the signal FASTER than the speed of light ANYWAY for the propagated signal to arrive at the end of the stick faster than the speed of light, so the whole question doesn't really even make sense at all.

This doesn't happen, of course. When you move (transfer force into the stick from another piece of matter) you are essentially initiating a compression wave upon contact which travels through the object at the speed of sound.

When you push or pull the end of a stick made of a material, you start a pressure wave moving thru the stick at the speed of sound in that material. Pushing or pulling slowly only makes the wavelength longer; it doesn't alter the wave speed. For steel, it's about 6.5 km/s; for Kevlar, about 8 km/s; all other known materials are slower. The speed of light is 300,000 km/s. Also, you would have to pull, rather than push, or the stick will bend, and the wave will become a shear wave, which is much slower.

There are several threads on this top.

There are also several threads on so called "quantum teleportation". This one was active until 19 hours ago.

Think of it this way, Saturn. There is no such thing as a solid.
There are are just forces which are more compressed or less compressed.
Our interpretation of the interaction of our senses with these forces draws us a picture of reality that enables us to function in our surroundings. But this perception is not reality. The pencil is empty space held together by forces, and is only solid by definition.

I've experienced astral travel, moving around a dentist's surgery and looking in my own mouth as I watched what he was doing. So have many other ATS posters. I expect harnessing astral travel, rather than physical forces, will enable us to travel anywhere instantly without the problems that physical travel entails.

I'm curious. What sort of temperatures and radiation would be encountered outside the heliosphere, and what effect would these have on manned spacecraft?

reply to post by SaturnFX


Simple answer E=MC^2(+1), or E=MC^2(+N), thats how to go FTL, the speed of the photon may be @ C but the rotational axis of the photon is exponentially faster as the radius of the photon sphere (as a particle) travels a hell of a lot faster.

The smaller the diameter, the faster the travel.

Happy Hunting

HADES

It seems that if you had a really long pencil, like a few light years long, and you pushed one end, you would set up a wave which would travel at the speed of light, down the pencil and arrive at the other end a few light years later, causing the tip to move.

The shorter the pencil, the less noticeable the delay.

ok, thanks for all the replies.
I would like this demonstrated in a lab, but it does sound reasonable that there would be a slight "spring" effect no matter what the material, making the transfer of motion not violate the speed of light.

so, me pressing the pencil forward a inch will, if the pencil is 10 million light years in length, take at least that long for the other side to react...

If I am reading things properly here, it may take alot longer for the other side to move forward (difference of 6k/s verses 300k/s) meanwhile the compression wave races down the length.

Damn, so much for my plans to create a trillion mile typewriter for instant communications

back to perpetual motion for me...now where did I put those magnets

Originally posted by mike_trivisonno
It seems that if you had a really long pencil, like a few light years long, and you pushed one end, you would set up a wave which would travel at the speed of light, down the pencil and arrive at the other end a few light years later, causing the tip to move.

The shorter the pencil, the less noticeable the delay.

As I stated earlier, it's the speed of sound, not the speed of light. If your rod is pure diamond, the wave speed will be about 1/25,000 of the speed of light.

Check out these references: Hyperphysics, Hyperphysics2

The speed of an acoustic wave in a solid is a function of bulk modulus, shear modulus and density. The momentum of the wave is equal to the applied force times the time it is applied. Since momentum is also mass times velocity, the velocity is slower for denser materials. Modulus is like stiffness. The velocity is faster for stiffer materials. For the speed of sound to equal the speed of light, the material would have to be infinitely stiff or have zero density.

Also, as stated before, to get an acoustic wave in a thin rod, you need to maintain positive tension. You either reduce the tension or pull on the near end. Pushing would only make the pencil bend; so you would get a much slower longitudinal wave. Then you're talking about a vibration on a string; the formula for that is v = √(T/μ).