Superconductivity at room temperature??

[johanfprins]

Wrong: johanfprins: How do you stop your charge-carriers from scattering?is based on the physical fact that resistivity is caused by charge-carriers scattering from the lattice. If you have scattering then you have resistivity.

I am delighted that you at least understand this!

So to have no resistivity you have to stop the charge-carriers from scattering. This is impossible with electrons since they are fermions.

It is impossible for any free charge-carriers that can be accelerated; whether the charge-carriers are fermions or bosons is immaterial in this regard.

Take liquid helium4 as an example: The atoms are bosons which form a superfluid. If one decants this superfluid from a beaker above a table, these atoms are free to accelerate down to the table: And guess what? They scatter when they hit the table. Thus being bosons does not prevent them from scattering when they are being accelerated. So how does the mere fact that charge-carriers are bosons prevent them from scattering?

Cooper pairing allows electons to act as bosons.

Fine, but it does not prevent these bosons from being accelerated by an electric-field and can thus not prevent these accelerated bosons from dissipating the kinetic energy they have gained by scattering.

ETA: You do not need to discuss the BSC model first or compare your model to it.

I am going to discuss it in order to show that it cannot explain the absence of an applied electric-field and also not the absence of scattering (as I have just now pointed out)

Many people here are familiar with the BCS model (me for example) and so you will be just wasting your time doing more than linking to a good description of it.

A “good description” in the main stream literature will not be enough to illuminate why this model cannot explain superconduction.

 

[johanfprins]

The divergence of the current is irrelevent to Gauss's law which is what we are discussing.

I have skipped your post just above, since this post is a summary of what you have said:

What I am pointing out is a conundrum: When you apply Gauss' law you obtain a divergence in the electric-flux: When you apply (div)J=0, you find that the charge-carriers cannot statically accumulate at the interface: Thus, the charge you require to explain the divergence of the flux cannot be caused by the accumulation of charge-carriers at the interface: It must have another explanation. I think I know what it is. But you guys are so brilliant that I will leave it as an excercise; since it is irrelevant to the fact that the divergence cannot be caused by the static accumulation of the charge-carriers at the interface: Charge-carriers can only accumulate at an interface when there is an electric-field and when there is no current flowing through the interface.

 

[johanfprins]

Think about it, Johan, please: compare two lengths of wire, equal cross-sections, but one made of copper and one made of iron (with one end attached to a voltage source and the other grounded, say). Do you really, truly, honestly believe that when the same electric field (i.e. voltage) is switched on across each wire, the current builds up as exactly the same function of time?

Maybe you have never heard about it (which will not surprise me one bit) but resistors can be connected in series and in parallel: And the two situations are completely different. If the resistance of the iron is R_IR and the copper is R_CU then when coupled in parallel they have a combined resistance of R_PAR given by:

1/R_PAR=1/R_IR+1/R_CU

While when connected in series they have a combined resistance of R_SER where now:

R_SER= R_IR+ R_CU

Of course it doesn't. It can't, because the current after a while asymptotes to two different values, since the two wires have different resistance and I=V/R.

Yes if they are connected in parallel you are correct: But the iron and copper we have been discussing all along are connected in series. Thus your argument is as usual irrelevant nonsense.

In our Cu-Fe-Cu sandwich problem when you switch on the field the currents in the iron and copper sections aren't going to be the equal either for a time.

Really!? Their combined resistance is R_SER and Ohm’s law tells you that when you switch on a voltage V across the two resistors the current I within them must be the same every step of the way: since I*R_SER=V

Therefore there is a necessarily a divergence in the current at each interface,

As usual wrong again! And the rest of your argument is such nonsense that I will not even quote it further.

Note that this whole picture is both intuitively crystal clear

That is your problem: You rely on your intuition instead of facts and logic. The fact is that as soon as you switch on the voltage an electric field appears near simultaneously at every position so that the charge-carriers must also start off moving with the same current I everywhere.

and consistent with all relevant equations (current continuity, Gauss' law, and Ohm's law), whereas yours is inconsistent with Gauss' law and/or Ohm's law.

This is really laughable: It is you who are inconsistent with Ohm’s law which mandates that the current I must be the same within both the copper and iron when they are connected in series.

 

[sol invictus]

Really!? Their combined resistance is R_SER and Ohm’s law tells you that when you switch on a voltage V across the two resistors the current I within them must be the same every step of the way: since I*R_SER=V As usual wrong again!

Yes, Johan - you've learned about Ohm's law from us in the last few pages of this thread, and we know you're very proud. It is indeed Ohm's law in the form you mention above that shows that there is charge accumulated at the interfaces once the system settles down.

But you didn't learn very well, because Ohm's law is a statement about steady states. It's not valid just after the voltage is turned on, any more than it is valid just after (say) a resistor is connected across a charged-up capacitor and the current is instantaneously zero (even though V and R are finite).

 

[johanfprins]

To summarize, for Johan to be correct, one needs to believe at least two unphysical things before breakfast:

(1) Charge carriers in the Cu-Fe-Cu sandwich always behave like a perfectly rigid body with constant linear density - in other words, the current in each section is always exactly equal, despite the fact that Cu is a much better conductor than Fe.

(2) Either Ohm's law is wrong or Gauss' law is wrong (or both), because the two combined tell us there is a charge accumulation at the interfaces.

I decided to only respond to this part of your post since the initial part is just the usual claptrap which you keep on posting.

(1) The term "rigid body", as used by you, implies that the charge carriers are bonded to each other. This is obviously not the case. In the context I tried to use this, is to point out that according to Ohm's law a voltage V across a circuit consisting of resistors in series, always causes the same current I to flow through each resistor. It is obvious that this is similar to an incompressible fluid; and therefore the charge-carriers themselves cannot accumulate anywhere within any of the resistive-elements and also not at the interfaces between the these elements.

(2) Ohm's law is not wrong: You apply it incorrectly in order to intuitively conclude that the charge-carriers can accumulate while a current is flowing. Gauss' law is also not wrong but after you applied it you conclude intuitively that the divergence of the electric-field at an interface is caused by the accumulation of charge carriers within the interface; while this is not physically possible.

 

[sol invictus]

(1) The term "rigid body", as used by you, implies that the charge carriers are bonded to each other. This is obviously not the case. In the context I tried to use this, is to point out that according to Ohm's law a voltage V across a circuit consisting of resistors in series, always causes the same current I to flow through each resistor.

Ohm's law only applies to the steady state, Johan. I gave you an example just above of a transient where it doesn't apply (an RC circuit immediately after you connect it). So it says nothing about our case except what the final steady state will be - and in the final steady state, we all agree that the current is equal in each component.

It is obvious that this is similar to an incompressible fluid; and therefore the charge-carriers themselves cannot accumulate anywhere within any of the resistive-elements and also not at the interfaces between the these elements.

I'm glad you agree that your claim requires that charge carriers behave like an incompressible fluid. Since that's in explicit contradiction with millions of experiments (like charge accumulating on or discharging from capacitor plates), do you now acknowledge that you are wrong?

 

[PiedPiper]

Having followed this thread since its beginning, I must say I am still a little confused. I just don't see what the problem is here. I'm not a stranger to academic / scientific debate, but I've never seen a debate that was so ridiculously one sided before. Surely something within a person must scream out when there is so much opposition to their point of view. I know for myself, from experience, that if I'm the only person in a room defending one point of view / one theory, that I have to be very careful. It's probably not the case that there is a conspiracy against me, or that everyone else (all trained scientists equal to me) are wrong. I'm either not explaining my point of view correctly and clearly enough, or my point of view is wrong. Either way, the blame is on me.

I just have to express my confusion because I see it happening in this thread and also in some other famous threads here. How does a scientist fall prey to "my theory is correct and everyone else is wrong", when all of their training up to this point (to question, to investigate, to modify theories based on result) and all of their common sense is screaming out that maybe it's *them* that are mistaken, not everyone else? I don't see how anyone can call themself a scientist, or even a critical thinker, with such blinders on. Someone help me to understand

 

[johanfprins]

Seriously, Johan, how can you not understand this?

In the middle of the copper, there are (+) and (-) charges. They are equal in density, so the net charge density is zero.

This is the response I wanted to get from specifically you Ben. Do you know why? Because you have argued that when it comes to a magnetic field around a conductor the positive charges do not play any role; and therefore such a current flowing through a vacuum without any positive charges will give the same magnetic-field! Bravo: When it suits you the positive charges play no role but when you require them, they are suddenly there. Now they are there now they are gone: The same paranormal claptrap that is called "wave-particle" duality". When will physics become real again?

That's why the flux divergence is zero---your Gaussian surface surrounds both electrons and nuclei in equal numbers.

Correct! And you will find that within your Gaussian volume across the interface the charge relating to the charge-carriers and the charge relating to the positive charges are still equal. Thus the change in the electric-field is not caused by a static accumulation of charge-carriers within the interface.

The (-) charges are moving to the right, so the net current is nonzero. We measure current and charge-density separately. They're different things.

Thank you: At last you are talking sense: So you must agree that when the current is constant around a circuit, the charge-carriers cannot accumulate within any volume to generate more negative charges than the positive charges relative to which the are flowing.

 

[johanfprins]

I have decided not to respond to the insults in posts 2092 and 2093

Johan, I want to remind you about this post and encourage you to go through it.

Remember how this works. Gauss's Law has done just fine with everything you've thrown at it---bulges, iron, vacuum, superconductors, interfaces---except for the intuitive insistence that current and charge-imbalance can't coexist.

This is not what I have been arguing: What I have tried to argue all along, and I agree that some of my arguments could have been better, is that the charge-carriers themselves cannot statically accumulate within the interface: That there can be a dynamic imbalance between the moving negative charges and static positive charges within each element, and that this imbalance can be different within the different elements is something totally else. The fact remains that once an equibrium current I flows, the charge-carriers cannot statically accumulate at any cross sectional surface along the circuit.

You have offered no evidence whatsoever for this assertion; your attempts to prove the assertion have all contained explicit intro-E&M mistakes, like confusing flux with current.

So are you saying that when one integrates a current density J across a surface area the resultant current I is not a flux of the current density? Does flux only apply for certain vector fields and not for others?

Since you get so badly tangled in the math, I will give up trying to use E&M laws to convince you of anything.

Good idea, since you have proved consistently on this thread that you cannot apply Maxwell's equations correctly. Your use of E&M laws have been totally confusing because you are confused.

The goal of the above post---which again, please do read carefully and without making the usual mistakes again---is show you, nonmathematically, that one part of your intuition is actually incompatible with another part. Your belief that capacitors can store free charge (you do believe this, right?)

I have never said that a capacitor can store free charge: When you charge up a capacitor, you "pump" free charge carriers from one plate to the other and they thus accumulate within one plate and leave positive charges within the other plate, precisely because they cannot flow through the plate into the space between the two plates of the capacitor.

is incompatible with your belief that charge-excesses go away in the presence of current.

I would have thought that it is very obvious that you cannot charge a capacitor when you short circuit the capacitor plates by, for example, placing a block of metal between them that makes contact with both plates. A current will then flow so that there cannot be any charge-accumulation. Or do you think that a capacitor is a battery? There is a difference you know!

 

[johanfprins]

Yes. Because Gauss's Law does not admit anything except "actual charge" as a cause for divergence of an electric field.

You are again just stating what you want to state: Note that I have stated actual charge-carriers: And I still maintain that when a constant current is flowing through a copper-iron interface the charge-carriers cannot statically accumulate within the interface. Thus, the divergence you are calculating does not relate to the static accumulation of charge-carriers within the interface.

Remember, Johan, that you spent several pages insisting that the divergence was zero or nonsense?

Maybe I was not very clear: My point I tried to make is that when a current is flowing any diverence cannot be the result of the static accumulation of charge-carriers at any interface.

Any apologies for the five pages you spent insulting everyone who tried to tell you so?

It seems that we have been arguing past each other since my only argument was that the divergence cannot be caused by the static accumulation of the charge-carriers. If I have been misunderstood because I have been unclear on this, then I do apologise. I hope that my viewpoint is now clear.

 

[johanfprins]

Hi D'rok, I do not know if you have been following our attempt to educate johanfprins about electromagnetism.

However I will (try to!) summarize the current topic. The example we are talking about is a copper-iron-copper sandwich with a constant current running through it. The question is whether there are charges accumulated at the interfaces or not.

Right here you are already going wrong. The issue is not unspecified charges but charge-carriers that accumulate by becoming immobile at the interface. The latter is not physically possible. Thus you will have to look for a different type of "charge-accumulation" than assuming without any proof that the impossible accumulation of charge-carriers is suddenly possible.

 

[D'rok]

Thanks. I think I more or less understand that explanation.

As a lurker, it seems to me that you guys and Johan don't even speak the same language. I think when you say for instance this:

The question is whether there are charges accumulated at the interfaces or not

...it means something completely different to Johan than to you.

Dunno. It's hard to separate the signal from the noise in this thread.

Hi D'rok, I do not know if you have been following our attempt to educate johanfprins about electromagnetism.

However I will (try to!) summarize the current topic. The example we are talking about is a copper-iron-copper sandwich with a constant current running through it. The question is whether there are charges accumulated at the interfaces or not.

Right here you are already going wrong. The issue is not unspecified charges but charge-carriers that accumulate by becoming immobile at the interface. The latter is not physically possible. Thus you will have to look for a different type of "charge-accumulation" than assuming without any proof that the impossible accumulation of charge-carriers is suddenly possible.

Boy, did I ever get that one right.

Why do these things always boil down to boutique definitions of terms (or idosyncratic versions of basic concepts)? Shades of Mozina.

 

[johanfprins]

Thanks. I think I more or less understand that explanation.

As a lurker, it seems to me that you guys and Johan don't even speak the same language. I think when you say for instance this:
...it means something completely different to Johan than to you.

Dunno. It's hard to separate the signal from the noise in this thread.

I think that you have put your finger on the problem: I have all along been concentrating on the accumulation of actual charge-carriers which, in order to do so, must become immobile at the interface. While my opponents argued that charge must play a role when you have a divergence: The mistake they are making is to argue that the charge they are arguing about must be accumulated charge-carriers trapped at the interface. It cannot be the latter.

 

[sol invictus]

Boy, did I ever get that one right.

Why do these things always boil down to boutique definitions of terms? Shades of Mozina.

The notion that it's some other form of charges besides the "charge carriers" that accumulate at the interface is a semantic absurdity, even apart from the physics of a metal. There's no charge at the interface before the wire is connected to the voltage; afterwards there is. So, charge accumulated at the interface. But according to Johan, those charges cannot be "charge carriers".

Whatever.

If you're interested in reality-based physics, the charges that accumulate are of course electrons (on one interface, and a lack of electrons on the other, which means there's a net positive charge there) - the same kind of electrons that carry the current in steady state. They are not "bound charges", because metals have plenty of free charges available to flow wherever the electric fields push it.

 

[D'rok]

The notion that it's some other form of charges besides the "charge carriers" that accumulate at the interface is a semantic absurdity, even apart from the physics of a metal. There's no charge at the interface before the wire is connected to the voltage; afterwards there is. So, charge accumulated at the interface. But according to Johan, those charges cannot be "charge carriers".

Whatever.

If you're interested in reality-based physics, the charges that accumulate are of course electrons (on one interface, and a lack of electrons on the other, which means there's a net positive charge there) - the same kind of electrons that carry the current in steady state. They are not "bound charges", because metals have plenty of free charges available to flow wherever the electric fields push it.

I think I can conceptually understand that, but I still have no idea what Johan means by "excess" charge carriers. In these examples charge carriers = electrons, so what does it mean to say "excess" electrons. It makes no sense at all to me.

 

[johanfprins]

Yes, Johan - you've learned about Ohm's law from us in the last few pages of this thread, and we know you're very proud. It is indeed Ohm's law in the form you mention above that shows that there is charge accumulated at the interfaces once the system settles down.

Nope! Once it has settled down there are as many charge-carriers as positive charges and all the charge-carriers are moving simultaneously to transport a current I along the whole circuit. There cannot be any accumulation of charge-carriers anywhere.

But you didn't learn very well, because Ohm's law is a statement about steady states.

I am glad that you realise this; since this is one of the things that theb BCS theory cannot explain: i.e. why the charge-carriers can attain a constant drift speed without being accelerated and scattered all the time.

It's not valid just after the voltage is turned on, any more than it is valid just after (say) a resistor is connected across a charged-up capacitor and the current is instantaneously zero (even though V and R are finite).

Correct again. My but you are advancing you know! When you measure the current by an ammeter while the current has not yet settled down, you are measuring the current through the whole circuit. And it is this current that settles down: Not different currents within the copper and the iron.

I just realised that you can use two ammeters: One in the middle of the copper and one in the middle of the iron. I am sure that such an experiment will prove your arguments above WRONG as usual!!

 

[johanfprins]

Having followed this thread since its beginning, I must say I am still a little confused. I just don't see what the problem is here. I'm not a stranger to academic / scientific debate, but I've never seen a debate that was so ridiculously one sided before. Surely something within a person must scream out when there is so much opposition to their point of view. I know for myself, from experience, that if I'm the only person in a room defending one point of view / one theory, that I have to be very careful. It's probably not the case that there is a conspiracy against me, or that everyone else (all trained scientists equal to me) are wrong. I'm either not explaining my point of view correctly and clearly enough, or my point of view is wrong. Either way, the blame is on me.

Unfortunately this argument is a cliche. Do you want to argue that it is impossible to have a room full of people where only one person is right while the rest are wrong? Obviously if you find yourself as the person who believes he is right and the others are not, you must take the viewpoint of the majority into account. But this does not mean that you must concede when the arguments thrown at you are based on standard dogma and the refusal to even entertain anything else.

I have found myself in this position before, and owing to the majority opinion against me (and this included people near to me like my own father and brother) I did not proceed to do what would have been the correct thing to do. Today I am very sorry. After I have studied in the USA, experienced the civil rights issues, and returned in 1966, I could see that Apartheid was wrong. But the more I advocated this, the more I was treated as if I am a fool. Was it a conspiracy? Not really: My white compatriots felt threatened by the presence of my black compatriots, and when people feel threatened they automatically react in this manner to any argument which they perceive as increasing the threat.

If I am correct about superconduction, and I am sure that I am, since the present theories on superconduction fail in so many ways to model so many aspects of these materials, then I am a threat to the mainstream practitioners in charge of superconduction research. A brilliant friend of mine who also has a PhD in physics, and have studied my model in detail, told me already in 2005 that even though I am correct, he doubt whether the mainstream will ever allow me to publish. I thought he was just pessimistic; but it turned out that he knew human beings far better than I did at that stage. There are many cases in history where one person differed from the majority and was proved correct, many times only after he/she has died.

I just have to express my confusion because I see it happening in this thread and also in some other famous threads here. How does a scientist fall prey to "my theory is correct and everyone else is wrong"

I take exception to this statement if it is aimed at me:

when all of their training up to this point (to question, to investigate, to modify theories based on result) and all of their common sense is screaming out that maybe it's *them* that are mistaken, not everyone else?

This is how a scientist must be: I agree that modern scientists rarely act in this manner anymore. Who are *them*?

I don't see how anyone can call themself a scientist, or even a critical thinker, with such blinders on.

Can you explain bettr what you mean by “blinders” please?

Someone help me to understand

I cannot understand what “help” you are asking for.

 

[ben m]

This is the response I wanted to get from specifically you Ben. Do you know why? Because you have argued that when it comes to a magnetic field around a conductor the positive charges do not play any role; and therefore such a current flowing through a vacuum without any positive charges will give the same magnetic-field!

Because that's exactly right. Look at the Biot-Savart law, Johan. It depends on J, the current density. The electrons (which are moving) have a (-) charge and a nonzero current density J (from q*v). The ions (which are not moving) have a (+) charge and a zero current density (from q*v when v=0).

Add up the charges and you get zero charge density. Rho_tot = Rho_e + Rho_p = 0.

Add up the currents and you get Jtot = J_e + J_p = J_e + 0 = J_e. The stationary protons don't contribute at all.

 

[D'rok]

It's simple, Johan. You refuse to consider that you might be mistaken. Instead, it's the entire discipline of physics that has been getting at all wrong for the last 80 years. And when you come against math and/or established physical laws, it is the latter that is incorrect rather than you.

Possible, but highly improbable.

 

[ben m]

When you measure the current by an ammeter while the current has not yet settled down, you are measuring the current through the whole circuit.

Nope. You're measuring the current through the ammeter. In a circuit that has (as you say) "not settled down", it is not true that the current is the same everywhere.

What do you think you're doing? You think you're using Kirchoff's law of constant current? Sorry, read the fine print:

Kirchoff's Current Law is only valid if the charge density remains constant at the point to which it is applied. Consider the current entering a single plate of a capacitor. If one imagines a closed surface around that single plate, current enters through the surface, but does not exit, thus violating KCL.

Like we've been saying for, what, eight or ten pages now?

(Here's an educational aside for people other than Johan. Johan, you should skip it and go back to thinking about my capacitors post.)

There IS quantity whose flux is strictly conserved in E&M. Current can diverge, that's why we have both sides of the equals sign in the continuity equation. However, current plus displacement current is strictly conserved. The quantity

J + J_D = J + epsilon₀ dE/dt

is always divergenceless. In the iron-copper-iron example, during switch-on, the current in the copper is larger than the current in the iron (J_Cu > J_Fe, remember?) but the electric field is decreasing (remember? It is dropping from J_Cu*rho_Cu to J_Fe*rho_Cu).

J is not constant through the circuit (J_Cu != J_Fe). That's fine, Kirchoff does not demand that it be.

But notice that J + J_D is constant through the circuit. (J_Cu + dE_Cudt == J_Fe). Which is good, because that's an actual, immutable law of physics.)