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Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

arxiv.org

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Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#351

Post by segfaultbuserr »

Loughla wrote: post #347
ajnin wrote: post #299

I'm puzzled by this, looking at the resistance versus temperature graph they're not demonstrating zero resistance at 110K, they're demonstrating that at 110K the resistance becomes so low that it reaches the noise floor of their instrument. It's a stretch to call that superconductivity because when it come to that it needs to be actually zero, as in "I can put a current in a loop made of the material and come back on…

Really, really, really Stupid question (yes, capital S stupid). Several hypotheticas here that got me thinking: If superconductor exists at room temperature, and if I understand you correctly, it can hold a charge, essentially, indefinitely. Could I get a roll of it and charge it and throw it at someone to kill them? Or could I fry a passing car by throwing it at the car?

You certainly can use it as a batteryless inductor coil to zap people, similar to how you zap people with a charged capacitor. But a superconductor is limited by the magnetic field strength it can support. When the magnetic field strength goes up beyond the critical field by increasing the current, superconductivity is lost. In superconducting magnets, this causes a catastrophic failure called a "magnet quench". So a superconductor cannot store unlimited energy. In the original LK-99 claim, the critical current is 200 mA, it's not much.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#352

Post by gilbetron »

jcranmer wrote: post #47

Looking at the key temperature-resistivity graphs, this feels like the data doesn't support the conclusion that there's a superconductor here. The temperature-resistivity graphs of superconductors I've seen all have a fairly steep cutoff--a sharp, vertical line at critical temperature. The log-scale here complicates my intuition, but what I see is a gradual transition into noise range. Also, the graphs I've seen have…

On log-scale, a line will be an exponential in a linear curve. Here we have a curve on log-scale arcing down, which means it drops faster than exponential, which is, more or less, a cliff-like dropoff.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#353

Post by TylerE »

tomohelix wrote: post #30

Summary of events so far: The claim: Room temp (~300K) superconductor exists and we got it! The replication attempts: The production method is so poorly documented only a fraction of the samples being made shows any interesting properties. And among those interesting ones, results varies. Very few, if any, attempt actually completely shows the entire spectrum of properties and behaviors of a true superconductor at ro…

Would a ~200K superconductor be useful, if such a beast exists? Obviously not as good as room temp, but at least that's a temp you can maintain with dry ice and not liquid nitrogen.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#354

Post by gus_massa »

sparrowInHand wrote: post #221
Tade0 wrote: post #194

Earlier quoted context omitted.

> I'm actually surprised by the sheer lack of people commenting in the more-or-less-perma-LK-99 threads who show skepticism of the results. You're not seeing them because every thread with a significant percentage of sceptical voices trips the HN flamewar detector, which goes off when there are more comments than upvotes. I've counted three threads where this happened. It's the reason why the front page wasn't plaste…

So, the accurate term for scientific debate on HN is a cold-flamewar?

Sometimes the mods remove the automatic "flamewar" penalty. Sometimes the add manual penalties.

My guess is that they are triying to keep in the front page only the last 1 or 2 articles that has an important update and enought discusion.

You can send them an email asking for clarification.

(I don't expect they have hard rules about this, only some general principles and hopefuly good judgement calls.)

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#355

Post by mrguyorama »

stcredzero wrote: post #321
obrix wrote: post #184

Earlier quoted context omitted.

MR imaging is possible with permanent magnets and resistive (copper wire wound) magnets at low field strengths, below 0.35T or so. Above that the heating of the magnet windings becomes excessive and it would be very difficult to maintain a stable enough field strength. Superconducting magnets are very nice as long as there is no quenching. The material used for conductors must be mechanically stable and perform consi…

The material used for conductors must be mechanically stable and perform consistently from one production batch to another. One reason why current high tc superconductors are not popular I was going to ask: Why don't we use the current high temperature superconductors, and start building grid interconnects? I guess part of the answer lies in the cost that would be incurred because of the mechanical properties of the…

The current best "High temperature", standard pressure superconductor only works at -150ish degrees Celsius. That's not as bad as cryogenic superconductors, but it is still a blocker for large scale use.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#356

Post by marcosdumay »

jseip wrote: post #157
marcosdumay wrote: post #96

Earlier quoted context omitted.

It's not that extraordinary. When people rush to replicate an experiment, everybody with a positive result has something to publish very quickly, and everybody with a negative result need a lot more time to be certain of it. The kinds of results we are seeing are very hard to get by chance or due to bad experimental setup. But as a rule, we can't really differentiate a real thing from random noise in as little time a…

"It's not that extraordinary." How is that possibly true? LK-99 is already amongst the highest-temperature superconductors ever found (with that claim substantiated by at least two independent research teams as of this moment).

If you push it, all the diamagnetism videos people published about reproducing it could be created by some weird and unlikely distribution of ferromagnetism on the sample. Except for the one that nobody knows where it comes from, that could easily be a fabrication.

That leaves the original, that is clearly diamagnetism, but still could be misleading in many ways.

We don't know how many labs are working on replicating this. So we have no idea how unlikely mistakes we should expect to see.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#358

Post by marcosdumay »

FrustratedMonky wrote: post #154
Analemma_ wrote: post #125

Earlier quoted context omitted.

I understand why a lot of people think this, but I don't think we can say that with confidence yet. Cold fusion "replicated successfully" multiple times in the 80s too.

Wasn't the problem with Cold Fusion that it did NOT replicate, and thus got sullied with a bad reputation, so nobody wanted to touch it. Then decades later, it's still kind of open question. Aren't there some studies still going on, more on the down-low since it has such a bad reputation. Kind of like the super-conductor, have to keep it quiet and make really sure before publishing. Sabine did video on Cold Fusion th…

Some stuff replicated. It was clearly not cold fusion.

Some people made a career studying the kinds of sonoluminescence needed to explain what that experiment saw. (And AFAIK, nobody found a use for the theory yet.)

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#359

Post by snowwrestler »

flavius29663 wrote: post #311
huthuthike wrote: post #304

Earlier quoted context omitted.

It's a lot less spooky when you consider that your desk can hold your coffee mug forever. It's exerting force on the mug, but not doing any work.

even more so as the mug literally levitates above the desk, the atoms of the mug are not really touching the atoms of the desk.

The atoms do touch, by interacting electrically--which is the physical definition of how anything touches anything.

Re: Observation of zero resistance above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

#360

Post by internetter »

dgoldstein0 wrote: post #51
internetter wrote: post #39

Earlier quoted context omitted.

The original report is billed as a "room temperature superconductor" (iirc up to 28c). If it is indeed a superconductor at room temperature, it would be the first of it's kind and enable functional usages for superconductors previously impossible.

The original claim was Tc of 127c - above the boiling point of water. Plenty of reason to doubt it though. Of course I'm hoping it's real.

Wow, that's crazy! I guess I missed the 1 in front. I'd say the more I read the more optimistic I become. Fingers crossed!!
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