Speed Of Electricity, superconductors

It is well know that the speed of electricity is much slower than light.

The speed at which the electrons themselves move is actually slower than molasses. In fact, in A/C currents, the electrons don't even move; they just sit stationary and jiggle back and forth at a rate proportional to the hertz.

I'm talking more about the propagation of the electrical signal, not the movement of individual electrons. I realize it varies depending on the resistance of the conductor, and that in a copper wire (copper being the most conductive element in the periodic table behind silver), the speed of the signal propagation is approximately 2/3 c.

http://en.wikipedia.org/wiki/Speed_of_electricity

My question has to do with superconductors. In a perfect superconductor, will the signal propagation speed = c? Or will there always be some slower limit?

Anyone know?

Are you saying that a superconductor will expel restmass?
That's interesting :)

No, because I'm not talking about the speed that the actual electrons move (a.k.a. "Drift").

I'm just talking about the propagation of the electrical signal.

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Here is an unrelated, but similar mental picture that often comes up on these boards:

Take a solid metal rod, a million miles long, floating in space. If you somehow magically "jiggle" one end, won't the other end jiggle instantaneously, thus circumventing normal restrictions and allowing for Faster-Than-Light (FTL) communication? No, of course not; the atoms and molecules in the rod take time to transmit a compression force from one to another down the million mile length. That "signal" transmission is thought to occur at the c, even though the actual atoms that make up the rod do not move.

ok, i see, but i thought that objects containing restmass never would reach 'c' .
You say that you are talking about the information part here right?
And that' information' can reach 'c' (i know :)
what exactly are you referring to as information?
the electrical signal consisting of what
charge?

This post has been edited by yor_on on Oct 15 2007, 10:36 PM

I am referring to the speed at which the electric current can travel through the wire, meaning the speed at which adjacent electrons can transmit the charge from one to the other, and down the line (they don't have to move fast to do this).

It occurs at approximately 2/3 c in copper. My question is in a superconductor, does this increase to 1.0 c due to the elimination of resistance?

This post has been edited by Latrosicarius on Oct 16 2007, 08:46 PM

Awh man that's a spooky question :)
As nobody can tell me what charge really is i mean :)
If you're right in it being able to do 'c' then that most probably would mean that charge belongs to the same category as photons, no?
Nice question :)

I thought 60Hz was so slow that electrons do travel a significant distance. (As in more than a nanometer)

I don't think a superconductor would have the propagation speed reach c, though. You still have to have some movement of electrons don't you?

It seems to me that c is a speed limit of more than just light. It's also predicted that gravity propagates at that speed, and also, atoms transmit "pull" and "push" on other atoms at that same speed through covalent and ionic bonds. I'd tend to think that c is therefore a speed limit not just of light, but of spacetime, and that light/gravity/matter/etc are vicariously constrained to it because they exist within spacetime. Just a thought, of course.

Thanks

I found this page with some nice equations:

For AC Power:

How far do the electrons move as they vibrate back and forth? Well, we know that a one-amp current in 1mm wire is moving at 8.4cm per hour, so in one second it moves:

And in 1/60 of a second it will travel back and forth by

This simple calculation is for a square wave. For a sine wave we'd integrate the velocity to determine the width of electron travel.

So for a typical AC current in a typical lamp cord, the electrons don't actually "flow," instead they vibrate back and forth by about a hundred-thousandth of an inch.

I'm not sure, I'd think there would always be a certain amount of electron drift unless the temperature was at absolute zero. I know resistance goes down with temperature meaning the charge should travel faster as it gets colder, but TBH, I'm not sure if an electric current can work at all at absolute zero, even in a superconductor.

Does anyone have any data on the proportional speed of charge to electron drift? I'm guessing that as electrons drift slower and slower due to cold, the charge is passed between them faster and faster (so an inverse relationship). Anyone know? Maybe that's why superconductors work at cold temps.

This post has been edited by Latrosicarius on Oct 19 2007, 02:10 PM

Yes, that's how i too are starting to look at 'c' :)
Not as a property, more like a boundary, defining spacetime.

And as dimensions seem to go into each other instead of being 'things' of their own ( as i used to think in my imagination yeah, low threshold here :) i'm not sure i can see what space (empty) is any more.

One could define that as something 'devoid of matter'? perhaps, but 'virtual particles' make that a lie i think if they can interact with f ex hawking radiation. Now if they exist for 'real' :) And do interact, then we need a redefinition of what 'empty' is. And if we find it to be 'non empty' we need to explain how they can materialize, and that once more takes us to boundaries i think, just like 'c'.

And if so, i feel we should look at how we are defining dimensions. As concepts of Math they are ?easy? to handle (i don't really know:) but as a 'real' possible event we need something that easily relate to what we perceive. Ockham's Razor might be the wrong end of the binoculars but for us it has a practical value so i think that is what we should strive for. Maybe by refining what we see as dimensions we might find new ways of defining motion? and as that takes us all the way to 'c' :)

This post has been edited by yor_on on Oct 20 2007, 09:04 PM