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LK-99: Team of Southeast University observed zero resistance below 110 K

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Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#152
post #72

Earlier quoted context omitted.

Hypothetically, if we did end up with a worldwide superconducting energy grid, this would smooth load, which I would expect would make generation cheaper (since we can get rid of the need for expensive peaker plants and/or stationary storage requirements to handle local demand spikes). This would therefore make power companies more profitable, no?

Probably depends on the power company. The ones with a lot of coal plans would suffer; the ones with a bunch of solar/wind farms in prime locations that can dramatically expand capacity (think things like giant solar farms in the Australian outback) would benefit.

HVDC and HVAC transmission lines already only see single digit transmission losses over hundreds of miles

This has bigger implications in reducing wiring (and weight) costs in things like electric vehicles. Instead of fat finger diameter 20' copper cables, you could replace them with tooth floss.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#153

Earlier quoted context omitted.

[flagged]

> Purity does not affect Tc. Here's a lump of 100% Cu and another lump of 50% Cu and 50% "other". If purity doesn't matter, they must have the same properties? Why not just use 0.0001% copper in all our applications and save millions on material costs.

I know nothing about the theory of superconductors, but purity can affect electronic properties. For example, pure silicon is quite a poor conductor. If you dope it with a little bit of an n- or p-type dopant (an impurity), it conducts better. Add a bit more, and it conducts more. There are other effects, too.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#154

To me this is encouraging. 110K is really high! It's higher than YBCO which is what they make commercial "high temperature" superconducting tape out of. IMO if this is legit (I have no way of judging the source) then this is the first good third party evidence that the original researchers are not just doing some kind of fraud. A total fraud wouldn't have actually discovered a novel high-temperature, but not room tem…

> I'm surprised the prediction markets don't seem to be reacting.

Which way would you have the prediction markets go? Is this evidence for or against room-temperature superconductivity?

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#156

Earlier quoted context omitted.

It seems more and more like it's credible, but that synthesis is going to prove to be the issue. All these repro attempts are having too much success for there to be nothing behind the team's claims.

Credible? Their claim was “room-temperature superconductivity.”

It looks like they've at least discovered a novel high temperature (relatively speaking), low pressure superconductor. That does lend some credibility to the original claim, and perhaps reproduction of the result is trickier than originally thought.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#157

To me this is encouraging. 110K is really high! It's higher than YBCO which is what they make commercial "high temperature" superconducting tape out of. IMO if this is legit (I have no way of judging the source) then this is the first good third party evidence that the original researchers are not just doing some kind of fraud. A total fraud wouldn't have actually discovered a novel high-temperature, but not room tem…

The initial claim was speculated to be room temp and ambient pressure superconduction. 110K is a far cry from that.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#158
post #118

The Fig 3a)b) graphs are not showing superconductivity. That just looks like the resistance dips below the ~1e-5 mark and goes goes deep into the noise. That just looks like a normal conductor that has a positive temperature coefficient. edit: to add speculation, I think they made something that's not quite LK-99, and it's behaving like a normal conductor with no superconductance.

An excitation of 1mA and R = 1e-5 means the voltage is 10 nV (1e-8). Also the chart has a logarithmic y-axis.

I know, I'm just saying their test condition has a really high noise floor and once you dive into the noise floor there is no meaningful result.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#159
post #136

Earlier quoted context omitted.

Yes, I thought that that might be the case from day one. When they wrote that they had only a 10% success rate it was clear that they were not at all in control of sample purity. The big remaining question for me is what happens when they start traveling with the original sample to have another lab test their samples and how those results compare with both the original results and the independently recreated differen…

“Purity” is a really overloaded term here. There are vast set of material properties that simply don’t map to a definition “purity” as in some homogeneous concentration of a material. This is so early no one likely knows exactly what configuration of material to “purify” for the intended outcome. There will likely be years of not decades of looking at differences in the materials and performance of related materials…

Yes, true, let me unpack that then:

- purity as in the sample is uniformly constructed of the right atoms but they are not in the right configuration

vs

- purity as in the sample contains atoms that shouldn't be there in the first place

and finally

- purity as in: the sample that purportedly did show room temperature superconductivity turns out to be the impure one and that impurity is so poorly understood that we currently can not replicate it accurately, but a test by an independent lab of the sample would verify the properties as advertised.

All of these are possibles, and not mutually exclusive.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#160

The Fig 3a)b) graphs are not showing superconductivity. That just looks like the resistance dips below the ~1e-5 mark and goes goes deep into the noise. That just looks like a normal conductor that has a positive temperature coefficient. edit: to add speculation, I think they made something that's not quite LK-99, and it's behaving like a normal conductor with no superconductance.

The noise is probably just an artefact from measurement.

that's almost literally the definition of noise.

I'm saying the results are useless because the noise floor is obscuring any interesting behavior (if any).

Some people are saying "well, the Tc is 160K, so this result is invalid"--the way I see it, the Tc is not 160K because the test setup is so noisy so you're not really seeing any superconductivity at any temperature (not because it doesn't exist, but because their test setup is shitty)

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