Superconductivity at room temperature??

[Ziggurat]

Where did they measure a voltage? Please supply experimental proof

How the hell do you think you change the current in a superconducting magnet? You apply a voltage. Are you really contesting this? Seriously?

Because if they are free charge-carriers an electric-field will accelerate them and then superconduction will be impossible.

But according to you, that shouldn't even matter, because there's no electric field. What does it matter what an electric field would or wouldn't do if it's never there? And that's according to your paper.

Again, you can't even see the internal contradictions you've created.

There is no field when a superconducting current is flowing: But there is an electric-field when there is no current flowing

Yeah, um... no. No, there isn't. When you have no current flowing through a superconductor, there's no electric field. Seriously, just take a piece of superconductor, and... leave it alone. No current, no field.

I am aware that I wrote this, but it has nothing to do with acceleration caused by a centripetal force as you want to claim.

I really don't give a damn what you want to attribute that acceleration to. But if you're moving in a circle, then you're accelerating. Non-accelerated motion is only linear. This isn't even freshman college physics, this is highschool physics. Newton's 1st law. It's true by the very definition of acceleration.

but subject to all the lies you have posted on this thread I have no problem in calling you a liar.

Of course you don't have a problem calling me a liar. You've insulted me from the start, well before I ever wrote anything hostile in response. You've always been uncivil, I have no expectation that you would suddenly start being civil now. In fact, it's likely to get worse over time. Whatever cognitive deterioration has led you to think that circular motion can take place without acceleration is only going to get worse over time. I'd be angry if it weren't so pathetic (in the pathos sense).

 

[CaveDave]

So what? If they are not able to interpret their results correctly it surely does not bar me from giving the correct interpretation.

Then, I don't understand why you would have chosen that page to link to in support of your assertion. You wrote:

...recent experimental evidence that Cooper pairs do not exist...

and gave a link to that article. If that citation fails to support your position, why use it?

ETA: Why did you not, instead, link to your own, correct, interpretation?

Correct! I will not post under another name and will most definitely not use different names as if I am different persons. I will never stoop so low but leave it to persons like Ben m, ziggurat etc. They can obviously live with a bad conscience: I cannot.

I apologize. It was only meant as a Tongue-in-Cheek wisecrack. I should have made that clear.

I don't understand the remark highlighted above, though. are you saying that they use sockpuppet identities, or are otherwise deceptive or disingenuous in some way? Can you provide evidence of this? I have observed their postings for some years now, and I have never seen any example of that behavior in them (although I could have missed something - I don't read every post); now, sometimes, they do get a bit impatient, esp. when someone who should know better refuses to see their errors, and if someone starts slinging epithets, they will give as good as they get, but I have never seen them actually attack the speaker (ad Hominum - as opposed to attacking the speech) unless "blood" has already been "spilt" by their opponent.

Your Mileage May Vary...

Cheers,

Dave

 

[Ziggurat]

I have observed their postings for some years now, and I have never seen any example of that behavior in them (although I could have missed something - I don't read every post); now sometimes they do get a bit impatient, esp. when someone who should know better refuses to see their errors, and if someone starts slinging epithets, they will give as good as they get, but I have never seen them actually attack the speaker (ad Hominum - as opposed to attacking the speech) unless "blood" has already been "spilt" by their opponent.

Your Mileage May Vary...

I cannot claim that I've never been the first to extend my claws. But I wasn't the first in this thread. In fact, he started using personal insults aimed at me very early on (post #123). For some time I made an overt effort to remain civil in the face of insults from johan, and asked him to act civilly himself. And he actually would stop, for a few posts. But it never lasted, and I drew tired of trying. So now I don't bother anymore.

 

[W.D.Clinger]

Page 7: "It should, however, be crystal clear that the only way in which an electric current can keep on flowing around a ring without requiring continuous acceleration, must be by means of perpetual motion!".So not only is this statement ridiculously wrong (ANY circular motion requires constant acceleration, or it's not circular),

Prove this wrong: You cannot.

Trivial Theorem Circular motion at constant positive speed implies nonzero acceleration.

Proof: Without loss of generality we may choose a Cartesian coordinate system whose origin lies at the center of the circular motion and for which the motion is confined to coordinates <x,y> for which x²+y²=r², where r is the radius of the circular motion. Letting the constant positive speed be s, the time t₁ that elapses during each revolution is the diameter divided by the speed, so t₁=2πr/s. Choosing a time origin so the position at time t=0 is <r,0>, the position at any time t is

[latex]
\begin{align*}
x(t) &= r \sin ( 2 \pi t / t_1) = r \sin ( (s/r) t) \\
y(t) &= r \cos ( 2 \pi t / t_1) = r \cos ( (s/r) t)
\end{align*}
[/latex]

The velocity, by definition, is the derivative of position with respect to time:

[latex]
\begin{align*}
v_x(t) &= \frac{dx}{dt} = r \cos ((s/r) t) (s/r) = s \cos ((s/r) t) \\
v_y(t) &= \frac{dy}{dt} = - r \sin ((s/r) t) (s/r) = - s \sin ((s/r) t)
\end{align*}
[/latex]

The acceleration, by definition, is the derivative of velocity with respect to time:

[latex]
\begin{align*}
a_x(t) &= \frac{d v_x}{dt} = \frac{d^2x}{dt^2} = - s \sin ((s/r) t) (s/r) = - \frac{s^2}{r} \sin ((s/r) t) \\
a_y(t) &= \frac{d v_y}{dt} = \frac{d^2y}{dt^2} = - s \cos ((s/r) t) (s/r) = - \frac{s^2}{r} \cos ((s/r) t)
\end{align*}
[/latex]

At any time t, the magnitude of the acceleration is

[latex]
\[
\left| \langle a_x(t), a_y(t) \rangle \right| =
\sqrt{\frac{s^4}{r^2} \left( \sin^2 ((s/r) t) + \cos^2 ((s/r) t) \right)} = \frac{s^2}{r}
\]
[/latex]

which is independent of t. Since the speed s is positive, the acceleration is always nonzero with magnitude s²/r.

QED

 

[CaveDave]

I cannot claim that I've never been the first to extend my claws. But I wasn't the first in this thread. In fact, he started using personal insults aimed at me very early on (post #123). For some time I made an overt effort to remain civil in the face of insults from johan, and asked him to act civilly himself. And he actually would stop, for a few posts. But it never lasted, and I drew tired of trying. So now I don't bother anymore.

Well, I had never seen (to my recollection) you bare your talons first, but I do know you carry them, concealed.

As far as I'm concerned, once Johann, or anyone else, breaks trump (Bridge term), then anyone else can lead it back: Fair is Fair, don'cha know.

Hoyle and Marquess of Queensberry concur, here...

Cheers,

Dave

ETA: I have been following this thread from the beginning, and that is how I remember it, too: The insults started w/Johann, you guys gave him a lot of latitude and suggested he cease, he would relent for a time, then rinse, repeat, and finally you guys gave up on deferring to his stature and returned fire. Glad my memory still functions...

 

[Ziggurat]

Well, I had never seen (to my recollection) you bare your talons first, but I do know you carry them, concealed.

I usually try not to be the first, and I'm pretty good at doing that in the science forum, but I've slipped on occasion in other forums. But I never complained about getting back what I gave.

 

[catsmate]

....snip.....

cold fusion of hydrogen at nickel with S. Foccardi

....snip.....

So he's a believer in Rossi's fake fusion machine too?

 

[Reality Check]

A single particle wave function has parameters for a single particle

Again you jump in without defining what a "single particle" is:
...snipped rant...

Again I jumped in to tell you the basics of quantum mechanics, i.e. the definition of a wave function

A wave function or wavefunction is a probability amplitude in quantum mechanics describing the quantum state of a particle or system of particles. Typically, it is a function of space or momentum or rotation and possibly of time that returns the probability amplitude of a position or momentum for a subatomic particle. Mathematically, it is a function from a space that maps the possible states of the system into the complex numbers. The laws of quantum mechanics (the Schrödinger equation) describe how the wave function evolves over time.

I disagree with the "probability amplitude" bit without the caveat that this is the Copenhagen interpretation.

The first thing that one learns about the wave function is that it has parameters corresponding to the particle or particles whose quantum states it describes. A single particle wave function has parameters for a single particle. This is really basic, johanfprins.

 

[W.D.Clinger]

A correction:

Letting the constant positive speed be s, the time t₁ that elapses during each revolution is the diameter divided by the speed, so t₁=2πr/s.

The highlighted word is incorrect. I meant to say circumference instead of diameter. The equation is correct, because the circumference is 2πr.

 

[W.D.Clinger]

Another correction:

Choosing a time origin so the position at time t=0 is <r,0>,

The highlighted point is incorrect. With the stated equations for x(t) and y(t), the position at time t=0 is <0,r>.

I apologize for posting so many errors to this previously pristine thread.

 

[Ziggurat]

I apologize for posting so many errors to this previously pristine thread.

"Pristine" isn't the word I would have chosen. I guess that's another mistake.

 

[dasmiller]

I apologize for posting so many errors to this previously pristine thread.

I'd been assuming that everything I'd seen in the previous 1,483 posts was correct, but now I'm having to consider the possibility that there may have been a few factual errors.

 

[ben m]

Because if they are free charge-carriers an electric-field will accelerate them and then superconduction will be impossible.

Yes, when there's an electric field in a conductor (super or otherwise), electrons accelerate. Accelerating allows them to change velocity, and therefore to change position, and they move into positions such that the DC E-field is zero. This works almost the same way in conductors as in superconductors; the difference being that in conductors the motion is lossy (i.e., there's frictional dissipation) and in superconductors the motion is lossless.

Again, as everyone has said, you charge up a superconducting magnet by applying a voltage to it. This causes an increasing current, with the rate of increase determined by the inductance.

If you want direct evidence that the voltage appears across the superconductor, not (e.g.) the leads or the injection contact: among other things, you can short out a superconducting magnet if you apply too high a voltage to it. The winding is a long SC wire with a thin insulator separating the windings. If your theory were true---there's never an E field along such a wire---there could never be a voltage difference between one layer of the winding and the next layer.

Experience shows that it is easy to get such a voltage difference, and indeed this is a common way to destroy a superconducting magnet. If you try to change the current too fast, the inductance kicks back a voltage drop along the wire, and this means there's a voltage drop across the insulation separating the windings, and you can actually get an arc discharge through this insulation. This can happen during a mismanaged quench, and that's half of the reason that "quench protection" is such a big deal in practical magnet engineering.

So yes, a superconducting wire can have a voltage drop along it. This voltage drop can, in practical engineering circumstances, be so large (many kV) that one end of the wire can arc-discharge to the other end.

It's just Faraday's Law of Induction, which works on superconductors just as well as it does on everything else.

 

[johanfprins]

How the hell do you think you change the current in a superconducting magnet? You apply a voltage. Are you really contesting this? Seriously?

Across the superconducting wire or across the circuit?

But according to you, that shouldn't even matter, because there's no electric field.

It is not there when a superconducting current is flowing since the charge-carriers leaving the injection contact have the same energy when arriving at the target contact. Therefore there can be no voltage. But if you do not inject charge-carriers, the voltage will be present and the charge-carriers must then not be accelerated by the voltage. Any material which has "free" charge-carriers that can be accelerated can NEVER be a superconductor since such charge-carriers can never convey a current without being accelerated. Read my section 27 to see how a current is injected and why it flows through an insulator as a super-current.

What does it matter what an electric field would or wouldn't do if it's never there? And that's according to your paper.

If the charge-carriers are free the electric-field is cancelled when you apply it WITHOUT injecting charge-carriers. In the case of a superconductor the electric-field is not there because the charge-carriers move without being accelerated: However, when not injecting charge-carriers the electric-field is not short-circuited and this polarises the anchored charge-carriers. This poltisation plays an important role in determining when a material becomes superconducting.

Again, you can't even see the internal contradictions you've created.

No it is you who are not able to think laterally.

Yeah, um... no. No, there isn't. When you have no current flowing through a superconductor, there's no electric field. Seriously, just take a piece of superconductor, and... leave it alone. No current, no field.

You must inject charge-carriers and for this you require an electric-field within the circuit outside the superconductor. You cannot have a current flowing from one contact to another through any material if you do not inject charge carriers: For this you do not need an electric-field within the material itself. Do you not agree with this?

I really don't give a damn what you want to attribute that acceleration to. But if you're moving in a circle, then you're accelerating.

For a normal continuous current yes: And you then get the formation of EM-waves. For a superconductor the energy used to move, whether linear or circular is "on loan" and cannot be dissipated: Thus even if a charge-carriers follows a non-linear path it is not being accelerated in the classical sense. If it were it would radiate EM.

Non-accelerated motion is only linear.

Classically yes. But we are talking about a QM effect.

This isn't even freshman college physics, this is highschool physics.

That is exactly your problem: You are stuck at the high school level.

Of course you don't have a problem calling me a liar. You've insulted me from the start, well before I ever wrote anything hostile in response. You've always been uncivil, I have no expectation that you would suddenly start being civil now.

I agree it will be difficult with you: But I will try.

In fact, it's likely to get worse over time. Whatever cognitive deterioration has led you to think that circular motion can take place without acceleration is only going to get worse over time.

It is not pure uninterrupted circular motion but motion caused by barrier-jumps from one position to the next. This changes the physics somewhat, even when a magnetic-field curves the jump-path.

I'd be angry if it weren't so pathetic (in the pathos sense).

I nearly wrote you something clever: But will refrain.

 

[johanfprins]

Then, I don't understand why you would have chosen that page to link to in support of your assertion. You wrote:

and gave a link to that article. If that citation fails to support your position, why use it?

ETA: Why did you not, instead, link to your own, correct, interpretation?

To me it is quite clear that this result supports my conjecture that Cooper pairs do not exist: Those people who took the time to read what I have wriiten in my book contacted me before I have seen this thread and they concluded that this result suppports the fact that Cooper pairs do not exist. If you read my model on the AC josephson effect, which I at first did incorrectly, you will see further evidence that the charge-carriers are singly-charged.

I apologize. It was only meant as a Tongue-in-Cheek wisecrack. I should have made that clear.

well I considered it an attack on my integrity and therefore I also lashed out.

 

[johanfprins]

So he's a believer in Rossi's fake fusion machine too?

You see what Dave's "tongue in cheek" is doing. I am now being dragged into a topic on which I have not posted any opinion anywhere.

I have not seen this new page with comments until late today. I will return when I have time and answer them except of course W D Clinger's irrelevant remarks.

 

[Ziggurat]

Across the superconducting wire or across the circuit?

Across the superconducting wire. Again, didn't you know this? This is really basic stuff!

It is not there when a superconducting current is flowing since the charge-carriers leaving the injection contact have the same energy when arriving at the target contact. Therefore there can be no voltage. But if you do not inject charge-carriers, the voltage will be present and the charge-carriers must then not be accelerated by the voltage.

Yeah, um... no. It's possible to have a voltage across a superconductor (again, superconducting magnets), but that's not a steady-state condition. You're claiming that it is: you're claiming that as long as you don't inject charge carriers, you can have a voltage across a superconductor. How then do you create such a currentless voltage? Stick the superconductor in the gap of a capacitor? Sorry, you won't get a voltage across the superconductor.

Any material which has "free" charge-carriers that can be accelerated can NEVER be a superconductor since such charge-carriers can never convey a current without being accelerated.

There's no problem with the charge carriers being accelerated. That is EXACTLY what must happen in order to change the current through a superconductor. Again, how can you STILL not know this?

Read my section 27 to see how a current is injected and why it flows through an insulator as a super-current.

No thanks. What I've already read is sufficiently nonsensical that I'm really not interested in wasting my time like that.

No it is you who are not able to think laterally.

I guess that's another word for freeing your mental processes from any need for consistency.

Classically yes. But we are talking about a QM effect.

Yeah, sorry, but quantum mechanics doesn't rescue you from that requirement. We've been through this already. And you failed to grasp the most basic aspects of quantum mechanics. I said it before and I'll say it again: you disagree fundamentally with standard quantum mechanics. There's little point in discussing superconductivity when your disagreement with mainstream physics occurs at a much more fundamental level.

I agree it will be difficult with you: But I will try. It is not pure uninterrupted circular motion but motion caused by barrier-jumps from one position to the next. This changes the physics somewhat, even when a magnetic-field curves the jump-path.

That makes the problem worse, not better. Now instead of merely having a radial acceleration, you've got a fluctuating tangential acceleration too.

I nearly wrote you something clever: But will refrain.

Sure, johan. Sure.

 

[W.D.Clinger]

I have not seen this new page with comments until late today. I will return when I have time and answer them except of course W D Clinger's irrelevant remarks.

Let's look at some of the "irrelevant" remarks Dr Prins is ignoring today.

Earlier today, he wrote:

For a normal continuous current yes: And you then get the formation of EM-waves. For a superconductor the energy used to move, whether linear or circular is "on loan" and cannot be dissipated: Thus even if a charge-carriers follows a non-linear path it is not being accelerated in the classical sense. If it were it would radiate EM.

Dr Prins is repeating his claim that accelerated charge carriers must radiate, but we showed long ago that his claim isn't always true: According to Maxwell's equations, a spinning ring of uniform charge density does not radiate, even though the charge carriers themselves are being accelerated (else their motion could not be circular).

Dr Prins responded to that fact by claiming that circular motion does not imply acceleration. He repeated that claim just two days ago, and demanded we prove him wrong, saying we "cannot". So I proved him wrong:

Trivial Theorem Circular motion at constant positive speed implies nonzero acceleration.

My proof contained two misstatements, which I corrected in posts 1489 and 1490. The proof uses classical definitions of velocity and acceleration. Contrary to Dr Prins's claim quoted above, charge carriers moving along a circular path are being accelerated in that classical sense, yet they do not radiate.

 

[Skwinty]

Trivial Theorem Circular motion at constant positive speed implies nonzero acceleration.

I guess the definition of implies is what Johan is banking on.

: to involve or indicate by inference, association, or necessary consequence rather than by direct statement <rights imply obligations>


: to contain potentially



: to express indirectly

 

[Reality Check]

To me it is quite clear that this result supports my conjecture that Cooper pairs do not exist: Those people who took the time to read what I have wriiten in my book contacted me before I have seen this thread and they concluded that this result suppports the fact that Cooper pairs do not exist.

Then you and "those people" are wrong.

• The paper explicitly mentions the existence of Cooper pairs.
• It is only your opinion (not fact) that Cooper pairs do not exist.

This misinterpretation (to put it charitably) was stated in

For recent experimental evidence that Cooper pairs do not exist, see:

www.physorg.com/news/2011-06-superconductivity-side-unmasked.html

Your inability to understand the article is obvious: It starts with illustrations of Cooper pairs !

The paper is about the discovery of a third type of Cooper pair, mediated by electrons in orbitals rather than lattice vibrations (phonons) or electron spin.

It is fairly simple physics that leads to the conclusion that electrons cannot be the charge carriers in low temperature superconductors.
Resistivity in metals is caused by the scattering of electrons by the lattice, especially by impurities (my thesis subject!) and defects. This requires that an electron be in an initial energy state and there is energy available to excite it into another energy state.
A metal has states up to and above the Fermi surface occupied.
This means that there are always electrons available to be scattered.

That is the reason why the majority of metals are not superconductors at low temperatures.

To get superconductivity, you have to somehow stop the electrons from scattering. This basically means depriving them of final energy states to be scattered into. That can be done by having an energy gap so that there is a minimum energy needed to excite the electrons into those states. Thus below a certain temperature the metal will be superconducting. The formation of Cooper pairs provides such an energy gap.