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

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

#341

Post by WindyLakeReturn »

WillPostForFood wrote: post #173
xvector wrote: post #166

Earlier quoted context omitted.

The probability of being able to reproduce this is unknown, there's no reason it couldn't be one in millions. If the original sample breaks in transit or experimentation we may have lost the only example of a room temp superconductor ever seen.

Invite some scientists and journalists to the lab to observe it?

I think they have done that. The catch is that these scientists are likely to take their time, because they want to produce something with weight behind it. This isn't lab #5234's attempt to reproduce it which showed some weird behavior that might be a success, this is the expert report on the original material giving second opinion on how valid the first's claim is. That needs to have more care, which means more thoroughness doing the research and more time spent writing up the final result with care. If lab #5234's attempt ends up being a false positive or experimental error, it will be one of many and won't mean much, but if this particular report is wrong or has a major error, that is going to be impactful in a negative way.

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

#342

Post by gus_massa »

Analemma_ wrote: post #125
tomohelix wrote: post #89

Earlier quoted context omitted.

Personally, I think we are past the point of this being nothing. There have been multiple confirmations of at least something unexplained going on. Maybe all of them are wrong but honestly, that is more of an extraordinary claim than saying this is something interesting, just not a full on room temp superconductor.

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.

In the cold fusion experiments, they were measuring an exess of heat. That's very difficult to measure, and some noise or experimental error can confuse the people.

No one measured a huge flow of neutrons, that were expected to be generated by the fusion and are more easy to distingish from noise.

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

#343

Post by cthalupa »

stonemetal12 wrote: post #323
jcranmer wrote: post #74

Earlier quoted context omitted.

> Worst case scenario, we got another class of high temp (warmer than liquid nitrogen but cold enough that applications are limited) superconductor but nothing revolutionary since at this point, it is pretty conclusive that there is something interesting with LK-99. I don't think that's the worst case scenario. The worst case scenario is that there is actually nothing interesting with LK-99, and everything we've seen…

I think it comes down to a lack of knowledge. I was pretty skeptical of the original claim, since RT has been a goal for a long time and no one has achieved it . So far all the repro attempts I have seen mention temps around 100K. I don't follow SC so 100k sounds "really cold" to me. It matches with my shallow understanding of SC "it is really cold". Maybe that is really warm in SC land. Either way there hasn't been…

100K is very cold. But if this result pans out, it's a very good thing for the possibility that LK99 really is an RTAPS.

There are a lot of explanations as to why they might not see bulk superconductivity at room temp - impurities in the sample (or the impurities being the SC) being the big one.

If LK99 is a superconductor at all, but not a RTAPS, it would be quite strange for the South Korean team to have made a mistake. It's quite difficult to accidentally cool something down to 100K, and if they were just getting false positives on their testing for superconductivity, it would be a massive coincidence that it happened to actually be one at 100K.

We're also seeing a lot of videos that show strong diamagnetism - this doesn't mean it's a superconductor, but all superconductors are perfect diamagnets. We have some unverified videos that seem to show things beyond just diamagnetism, with the material being stable in suspension over a single magnet, which a regular diamagnetic material cannot do. These pieces of material are too small to have been cooled down to 100K and stay there for the duration shown, as well as no frost appearing, etc., which would be quite difficult at that temperature in an environment with any humidity.

I think the bigger concern is around whether or not this is a valid result at all - the Real Deal scientists discussing it seem to have mixed thoughts there, particularly around the noise floor of the instrumentation equipment, etc. Some say that that doesn't matter, others say that it does, particularly since we don't see the kind of on/off drop you would in other superconductors, etc.

At worst, this replication attempt's result is from a misunderstanding of how their equipment works in this condition. At best it provides evidence in favor of LK99 being an RTAPS.

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

#344

Post by abracadaniel »

scarmig wrote: post #335
zeroonetwothree wrote: post #326

Earlier quoted context omitted.

Well, that position is right 99.9% of the time.

pg: "Being too cynical will cause you to miss out on the most important phase changes." Defaulting to "no" might get you the right answer the majority of the time, but it also makes you miss the times that "yes" is correct. And correct things that are a radical departure from the status quo are probably the most important and useful to get right. Skepticism is good (it's still ambiguous whether LK-99 is anything at a…

The brain loves an excuse to apply a noise cutting heuristic. There was an article a while back about that being a problem for general physicians, where the problem is usually simple, but very very rarely something serious. A doctor can appear good when they get it right 99% of the time, but they might achieve that by defaulting to “you’re fine, here’s some (ibuprofen/antibiotic/antihistamine/etc)”. Thus, their actual job is to identify that 1% with reasonable accuracy.

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

#345

Post by throwawaymaths »

HelloNurse wrote: post #225
jcranmer wrote: post #91

Earlier quoted context omitted.

> You're right that this is the worst case scenario, but each interesting replication or semi-replication, even sloppy replication, or theoretical model erodes at that. Not really. The ur-example of the worst-case scenario is cold fusion, and as we were reminded by somebody [1] early on, is that the first replications of the Fleischmann–Pons experiment were actually successful to some degree. Those initial replicatio…

Fortunately, observing a levitating fleck of diamagnetic material is far less error prone than measuring heat or neutrons in a messy cold fusion experiment.

Exactly this.

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

#346

Post by throwawaymaths »

jcranmer wrote: post #91
throwawaymaths wrote: post #80

Earlier quoted context omitted.

You're right that this is the worst case scenario, but each interesting replication or semi-replication, even sloppy replication, or theoretical model erodes at that. Being perma-skeptic is as bad as being a perma-fanboy Anyways your memory is really short. Don't you remember how when it first came out (not even a week ago) everyone was hollering that it was fake? Inb4 "extraordinary claims...": there is no fundament…

> You're right that this is the worst case scenario, but each interesting replication or semi-replication, even sloppy replication, or theoretical model erodes at that. Not really. The ur-example of the worst-case scenario is cold fusion, and as we were reminded by somebody [1] early on, is that the first replications of the Fleischmann–Pons experiment were actually successful to some degree. Those initial replicatio…

Yeah apologies, I was seeing lots of hot takes that it was fake on other platforms (like Twitter)

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

#347

Post by Loughla »

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?

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

#348

Post by atoav »

jfk13 wrote: post #211
atoav wrote: post #192

Earlier quoted context omitted.

You mean cryptography? Yeah, thanks to let's encrypt we are now reaching widespread adoption of TLS. You barely see any http websites anymore thanks to that.

You know perfectly well that's not what they meant.

Sure, but I am against the idea that from now on "crypto" has to be forever referenced to some ponzi schemes that provide no actual value.

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

#349

Post by foven »

Sharlin wrote: post #305
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…

Well, that's one of the reasons demonstrating the Meissner effect is considered a better evidence of superconductivity. Of course any physical experiment always has a noise floor and a finite error. You can't exactly ever measure zero resistance because your probes and the probe-sample interface have nonzero resistance… But looking at that graph, it would be an incredible coincidence if the resistance dropped like it…

Groups that typically do resistivity measurements on regularly measure low-temperature resistivities on conducting materials of ~ 10s of micro Ohm m. So if you're measuring in this range on a conducting material and hitting the noise floor with a SHARP drop, that's a pretty big indicator of superconductivity (assuming you haven't just broken your contacts which is a concern when cooling things down). I'm not so familiar with PPMS systems, but I imagine it has some built in auto-adjust on the sensitivities to where you can be pretty confident your noise floor is below these values.

What is complicating the interpretation here is the log scale (and lack of conversion to resistivity): It is amplifying the impression of the noise below what they call Tc, and making it harder to interpret the approach of the material to the transition point. The behaviour at the approach to Tc also doesn't really look like a metal, which should scale as propto T, or a semiconductor which should increase with decreasing temperature. Possibly a result of it being some horrible mixed phase ceramic.

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

#350

Post by atoav »

cthalupa wrote: post #301
eric_cc wrote: post #293

Earlier quoted context omitted.

> I read through this thread and I can't help to feel reminded of the discussion about cryptocurrencies. Same. Some people are simply wired to be perma-skeptics / perma-bears / perma-negative. This community is still full of people who truly don’t grasp how world changing bitcoin is. They are in complete denial, most often parroting unoriginal talking points that they’ve been handed from others. It’s easier to bypass…

I'll not take a personal stance on crypto in this comment, but it's really a stretch to try and compare the two. No one debates that there are significant and important uses for RTAPS. Lots of people debate if there are significant and important uses for cryptocurrency.

As I said I feel reminded of the discussions, I did not compare this scientific finding to crypto-assets per se. What I did however compare is the way this finding is being discussed in comparison to how crypto-assets have been discussed at a certain point in time.

More specifically I was comparing a specific trait of some actors in both of these discussions (the "I want to believe"-type). I stand behind that observation, although I see how people can read more into my comment, depending on where they are coming from.

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