Speed of electricity

[Jordan14]

Hi i'm new here,

Talking about the pole thing and pushing it at one end would make it move instantanously at the other end. In my opinion this is totally wrong, it is the fact that if you pushed a 100000000m pole 1cm for the pole to move at the instantaneous rate every atom in the pole would have to move 1000000000m and 1cm, instead each atom is moving 1cm forward in the time it takes you to push the whole pole 1cm. This however could be wrong.

[RQ]

We're not pushing the whole pole 100000m, but since it has an end that is long that much, one cm pushing would make it move 100000m and 1cm at the time it takes to push a pole 1cm thus a 100000m gain at instantaneous travel, but since the individual atoms aren't packed infinitely close to each other this argument has been shown to fall, though the pole would move faster than having been pushed a piece at a time.

[houserichichi]

For the speed of electricity refer to this, for example:

http://www.madsci.org/posts/archives/apr99/923595421.Ph.r.html

As for the big long superluminal stick try this:

http://curious.astro.cornell.edu/question.php?number=592

[RQ]

This pretty much sums up why this method is invalid as a faster than the speed of light. What I was saying is that this method makes electricity much faster than 123m/s

[PWrong]

Just to clarify, when one ball pushes against the other, which of the four forces is taking place? Is mechanical "pushing" simply another aspect of electromagnetism, like electricity and magnetism? If so, does it have a technical name?

If electromagnetism has three aspects in 3D, I suspect there may be a fourth analogue in 4D. In the simplest experiments with electromagnetism, the electric field, magnetic field, and the force produced are mutually perpendicular. I think each one is the dot product of the other two, or something like that. In 4D there is probably a fourth "sub-force" perpendicular to all three.

The only problem is that the three aspects are very different. For instance, electricity comes in monopoles, while magnets come in dipoles.

Sorry for going off topic a bit, but something tells me this thread isn't going anywhere

[jinydu]

Yes, its definitely an electromagnetic force on a microscopic scale. It obviously can't be any of the other three forces (strong and weak only work on subatomic scales, and gravity can't possibly be the culprit).

[Rkyeun]

Pushing a marble into a tube of marbles does not instantly make all the marbles move.

The effect of moving a marble forwards will propogate forwards through the tube at the speed of sound through marbles, modified by friction in the tube.

Likewise when you flip on a switch, the electrons move forwards, modified by the resistance of the wire. It's not even close to lightspeed, since electrons have mass and you're not producing infinite power to accelerate them with. I forget the technical term, but I want to say conductance or something. Electricity-as-water-in-a-pipe is a good analogy for most cases.

[chickendude]

for the example given with the spaceships going past each other..

if you are trying to show problems with instantaneous transfer of information by temporarily assuming that info can be transferred instantaniously, you cant use the theory of relativity because the original assumption throws out all of special relativity

so the example wehre the spaceships go by each other and the wire connecting them, wont work because special relativity is thrown out with the wire assumption

[jinydu]

for the example given with the spaceships going past each other..

if you are trying to show problems with instantaneous transfer of information by temporarily assuming that info can be transferred instantaniously, you cant use the theory of relativity because the original assumption throws out all of special relativity

so the example wehre the spaceships go by each other and the wire connecting them, wont work because special relativity is thrown out with the wire assumption

Well, not really. What I'm using is a proof by contradiction. I'm assuming that something is true, then showing that this assumption contradicts known facts within a theory.

Remember that Special Relativity has only 2 postulates:

1) The speed of light in a vacuum is constant for all inertial reference frames.

2) The laws of physics work equally well in all inertial reference frames. Another way to state this is that it is impossible to determine whether or not an inertial object is in absolute motion or not.

The claim that instantaneous communication is impossible is not a postulate that is accepted to begin with. Instead, it is a theorem, something that is proved from more basic assumptions.

You say that assuming that instantaneous communication is possible requires throwing out the theory of Special Relativity. Well, that's exactly what I was trying to show. That assumption contradicts the postulates of Special Relativity.

The best analogy I can give is the "conventional" proof that sqrt(2) is irrational, the one taught in school. I temporarily assume that sqrt(2) is rational, then I show that it contradicts the postulates of mathematics.

[chickendude]

oh i get that now

it appears to me that this whole pole idea circles around the idea that it is a perfectly rigid pole
how can this exist in life?

[jinydu]

oh i get that now

it appears to me that this whole pole idea circles around the idea that it is a perfectly rigid pole
how can this exist in life?

I've been trying argue that such a pole can never exist in real life.

[wendy]

Electricity in aluminium travels in holes. We know this from the hall effect. So an electrical current, even a dc one, would have to, to replace the electrons, push out 100,000,000 Coulombs of charge in the space of a gram. A small wire, a foot long, under the flow of an ampere of current, would then travel at the thundering rate of about an atom per second...

[chickendude]

I've been trying argue that such a pole can never exist in real life.

whats there left to argue then?
the pole doesnt exist

its almost common sense (to the relativisticly educated) that the pole cant exist

[RQ]

Electricity in aluminium travels in holes. We know this from the hall effect. So an electrical current, even a dc one, would have to, to replace the electrons, push out 100,000,000 Coulombs of charge in the space of a gram. A small wire, a foot long, under the flow of an ampere of current, would then travel at the thundering rate of about an atom per second...

We're not talking about an actual pole through which electricity runs. The pole is the electrons in a cable, which makes electricity in cables much faster than 123 m/s.

And yes there is instantaneous faster than light communication, because there are speeds faster than light, aside from Cerenkov radiation which isn't actually faster than c. Gravity is one example, though I heard recently that its instantaneous effects were questionable.

[wendy]

On the other hand, electricity in something like aluminium is "carried" by bubbles, not the flow of electrons. These are called holes.

The reference to a foot of wire would be that the "electricity travels at ...", not the "pole travels at".

And the phase transition of electricity is not a 'thing', but a 'progression of state'. That is, as the signal passes different places, it is being effected by different matter.

W

[Keiji]

Gravity is one example, though I heard recently that its instantaneous effects were questionable.

Gravity is just an effect of electrostatic forces on large objects.

[houserichichi]

The effects of gravity are not instantaneous otherwise we'd be able to get information out of a black hole, for instance, while is not allowed. It would take approximately 8 minutes for us to feel and see the effects of the sun disappearing, it wouldn't happen right away. Gravitons (something that haven't been detected yet) have no rest mass and thus travel at the speed of light.

And gravity is curvature, curvature is gravity. Nothing electrostatic about it, sorry bob

[Keiji]

And gravity is curvature, curvature is gravity. Nothing electrostatic about it, sorry bob

Go and argue that with my chemistry teacher. He's the one who told me that

[houserichichi]

I think I will :wink: Get him on here...let me at him!

[Keiji]

Well, sorry about that, I asked him today and he said he didn't

Dammit memory is an annoying thing

[RQ]

The effects of gravity are not instantaneous otherwise we'd be able to get information out of a black hole, for instance, while is not allowed. It would take approximately 8 minutes for us to feel and see the effects of the sun disappearing, it wouldn't happen right away. Gravitons (something that haven't been detected yet) have no rest mass and thus travel at the speed of light.

Information out of black holes is possible to get, as Stephen Hawking recently showed, and the black hole would be able to get information from us. The 8 min. you are talking about is the time light reaches Earth, not gravity. Gravity is made up of "H" shaped gravitons which hook to each other and only exist in the presence of matter.

[RQ]

The effects of gravity are not instantaneous otherwise we'd be able to get information out of a black hole, for instance, while is not allowed. It would take approximately 8 minutes for us to feel and see the effects of the sun disappearing, it wouldn't happen right away. Gravitons (something that haven't been detected yet) have no rest mass and thus travel at the speed of light.

Information out of black holes is possible to get, as Stephen Hawking recently showed, and the black hole would be able to get information from us. The 8 min. you are talking about is the time light reaches Earth, not gravity. Gravity is made up of "H" shaped gravitons which hook to each other and only exist in the presence of matter.

[houserichichi]

If the sun instantly disappeared it would take 8 minutes for us to move out of orbit. Gravitons, if they exist at all, are massless particles and thus necessarily travel at the speed of light. As far as being H-shaped, where'd you hear that? Reference? Are you referring to string theory, because it has never been verified, as promising as it may look...it's not wise to assume such giant leaps in faith are valid until you have evidence to support them.