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

https://arxiv.org/abs/2308.01192

by segfaultbuserr • 3 years ago

779 370 3 years ago

arxiv.org

squirrel_fetus• 3 years ago

Pretty cool! The question is how cool?

segfaultbuserr8• 3 years ago

According to the paper: Tc = 110 K, or around -163 °C. This is still pretty "cool", the existence of room-temperature superconductivity remains unverified. But assuming this paper is true, it means the material would still at least be a legitimate high-temperature superconductor in its own right, and the original claim would probably be cleared from being a deliberate fraud.

jfengel• 3 years ago

Cooler than dry ice but less cool than liquid nitrogen.

(Wakka wakka wakka)

crakenzak• 3 years ago

So exciting!

Just FYI, the wikipedia page for LK-99 has a very useful tracking grid of replication attempts with sources: https://en.wikipedia.org/wiki/LK-99

swagmoney1606• 3 years ago

We'll probably know for sure within the month!

generalizations• 3 years ago

Somewhat disappointed the russian twitter anon isn't included, since they seem to have made the first replication attempt that might have panned out.

silisili• 3 years ago

I'm curious why every tracker lists Argonne, though no status or progress listed. I'm sure there are a hundred other labs who've either done nothing, or are doing something without fanfare, so why Argonne?

JustARandomGuy• 3 years ago

Argonne is a highly regarded national lab; results from there would be highly credible. Also an Argonne staffer has gone on record[0] saying that they're attempting to replicate, while other labs have not said whether they're trying or not.

Personally I'm waiting for the Argonne results which should be done by the end of the week.

[0] https://www.science.org/content/article/spectacular-supercon...

psychphysic• 3 years ago

Anyone can edit Wikipedia.

Levitating2• 3 years ago

All the labs on that list have stated that they are working on replicating the experiment. That's also what is referenced.

Filligree2• 3 years ago

That grid is a direct copy of this one here: https://forums.spacebattles.com/threads/claims-of-room-tempe...

…but isn’t sourced, presumably because they don’t consider SB to be professional enough.

capableweb2• 3 years ago

Does not seem to be a direct copy (the Wikipedia missing things like Progress/Status, Reliability of Claim) and also, the Wikipedia page can be collaboratively kept up to date, while the other is a random forum post "owned" by one user and the owners of the platform.

awb• 3 years ago

The Response and Replication sections on Wikipedia seem far more skeptical and pessimistic about LK-99 than the average HN comment or news article.

jesprenj• 3 years ago

Is this one also written in Word so it automatically loses LaTeX-credibility, as was commented under the first paper? (:

ant6n• 3 years ago

Maybe some people wanna focus on the work and not on the geek cred.

(I need to write some thesis like thing soon, like 15 years after my masters thesis that was written in latex, and do I really want to bother setting latex up again and futz with templates and fight for correctly positioned figures, or just use Word and be done with it?)

marcosdumay5• 3 years ago

just use Word and be done with it?

One don't "just" use word, and it's certainly never done with. Unless you found a room temperature superconductor and half the people will simply not care if you wrote it in a piece of paper (yet half will care... for some reason), you will have to spend all your time fixing formatting issues and keeping things on their correct state.

I was stupid enough to write a paper in Word once. Given the choice, I will never repeat the mistake.

chungy• 3 years ago

Give TeXmacs a shot.

ramraj072• 3 years ago

I would have said latex gatekeepers are the worst, but now I know eMacs geeks so no. Or was it vim? Can never tell!

robotresearcher3• 3 years ago

‘eMacs’? It’s LaTeX that has the self-conscious capitalization!

danbrooks• 3 years ago

Encouraging evidence that the recent work on room temperature superconductivity might be real!

Still waiting for confirmation from multiple labs.

wsieroci• 3 years ago

Could someone explain why this is important? What is the consequence of the existence of Superconductors like that?

kvandy• 3 years ago

My understanding is that this unlocks future-tech... Post quantum computing, hyper efficient rail tech, fast charging batteries, etc. Pretty neat stuff, and even cooler to be able to follow this as it develops.

n2d42• 3 years ago

In the most ELI5 way possible, a superconductor is a material that doesn't lose any energy or produce heat when used as a cable/wire, and at the same time also a very strong magnet.

MRIs and powerlines are more obvious applications, but theoretically you can do a lot of cool stuff (batteries with zero energy loss, heat-efficient computers, etc [1]). If true, LK-99 would allow these things to happen at room temperature instead of negative whatever degrees, making them much more useful.

[1] https://en.m.wikipedia.org/wiki/Technological_applications_o...

booleandilemma• 3 years ago

I like this HN comment explaining it: https://news.ycombinator.com/item?id=36978704

dgoldstein04• 3 years ago

The biggest near future tech for superconductors: fusion power.

One huge area of exploration for fusion power is tokamok reactor design, which requires a very strong magnetic field to confine plasma within a round shape - typically a torus, though I think I read of one spherical shell.

I suppose these don't necessarily need room temperature super conductors, but cheaper and easier to manufacture superconducting materials to use as the magnets could make a huge difference. And I do wonder if allowing higher temperatures could aid in the operability of these future devices.

https://spectrum.ieee.org/fusion-2662267312 is one I read about recently, using YBaCuO as the superconducting electromagnet. Definitely sounds bottlenecked on production of it.

Fusion power, as any energy source that massively increases the amount of energy humans can harness, could be planet changing.

coderenegade2• 3 years ago

I think energy storage, motors / accelerators and weapons would come first. A superconducting linear motor would probably also make for a great cannon.

lifthrasiir2• 3 years ago

I'm very much conservative about this paper because while the graph in Fig. 3a says $T_c^{zero}$ being 110 K, the "zero" resistance is actually only 1e-5 Ω (!) and even if the sample is possibly superconducting its critical temperature would be much lower than 110 K anyway. I'm aware of the difficulty in obtaining larger samples, but the label in that graph is really misleading regardless.

nukros• 3 years ago

The random jumps in the resistivity around 250 K suggests that there is very bad contact resistance or a possible alternate current path. The drop in resistance doesn’t look like a typical phase transition (it is very broad in temperature). My guess would be that the voltage leads are not very well connected to the region of the sample that the current is flowing through. This could actually give a drop in the measured voltage (and therefore “resistance”) even though the actual resistance is increasing as the sample is cooled. It would be interesting if they also included two-point resistance across the current leads.

segfaultbuserr8• 3 years ago

One of the authors commented in their previous video pre-announcement that they suspect it was a probe cleanliness problem, which they would investigate later.

peyton• 3 years ago

Spec sheet says 10 uohm is as low as their probe goes.

pythonguython• 3 years ago

I believe certain it is near impossible to actually measure truly zero resistance. Instead, a sudden drop near Tc, combined with the meissner effect is what confirms superconductivity.

segfaultbuserr8• 3 years ago

The resistance curve stopped at 1e-5 Ω because it has nearly reached the resolution limit of their instrument. Using 4-wire Kelvin sensing, the measurement current was 1 mA, the voltage read-out across the material was around 1 to 10 nanovolts - this is around the scale that some of the world's best general-purpose voltmeters can measure down to. The authors assumed that the negligible voltage drop, combined with the abrupt drop and flattening of the resistance vs temperature curve is already a convincing-enough indication of superconductivity.

Hopefully more rigorous testing will be done by one of the teams later.

lifthrasiir2• 3 years ago

Which is indeed their argument. But in that case they haven't proved that $T_c^{zero}$ = 110 K, they only proved that $T_c^{zero}$ < 110 K. (And I should also note that $T_c^{zero}$ doesn't imply the actual critical temperature $T_c$, while the title strongly suggests so.)

amelius• 3 years ago

Curious, why didn't they use a larger current for the measurement?

kurthr2• 3 years ago

Well, it's at a 1mA test current (I'm assuming a 4 point probe to mitigate contact resistance) so 10u Ohm would give a 10nV DC signal. That's a pretty small voltage signal and comparable to a fairly standard chopper stabilized instrumentation amp rms noise at room temp near DC.

I'm not sure whether higher currents are all that reasonable. Cooling the precision amp is an option to reduce the noise figure, but at that point you'll want optical isolation and battery supply too.

https://www.analog.com/media/en/training-seminars/tutorials/...

throwaway849755• 3 years ago

A comment above says they are using https://www.qdusa.com/products/ppms.html with the DC 4-wire option.

All my instincts would prefer they were using the AC 4-wire option, given any reason to question results, and/or issues with contact effects, etc.

tines• 3 years ago

Isn't it a faux pas to put the degrees-symbol after the unit K?

extraduder_ire• 3 years ago

It's incorrect, yes. (about as incorrect as saying you're "1.8 degrees meters tall") But also, that's "U+2218 RING OPERATOR" on the page, not "U+00B0 DEGREE SIGN" but that may just be a typo.

Nifty3929• 3 years ago

Yes

tnecniv• 3 years ago

Clearly K is an element of some kind of algebraic structure here

DaiPlusPlus• 3 years ago

Ah yes, K, the Potassium Constant

nyc_pizzadev• 3 years ago

Worth noting that the sample used did not produce a Meissner effect, but was still superconductive at ~100K.

To further verify the superconducting properties, we conducted magnetic measurements on the sample, but unfortunately, no obvious Meissner signal was observed, indicating that the superconducting volume fraction of the sample may be very small. The preparation of high-purity samples are still a challenging task.

klimt• 3 years ago

This is one of my key takeaways as well. It's a shame they didn't include their magnetization measurements, even if it didn't confirm superconductivity. The first conclusive paper will have to demonstrate a superconducting transition in both electrical resistivity and magnetization.

soligern• 3 years ago

In the observations, this sample they tested did not exhibit the Meissner effect at room temperature. Which means it’s not the same thing the original team discovered?

Levitating2• 3 years ago

They stated no "obvious" Meissner effect was detected.

Possibly because the sample includes too many impurities.

downWidOutaFite2• 3 years ago

A 110k superconductor would not be revolutionary since we already have some in that vicinity.

slavetologic• 3 years ago

That's what I'm not understanding about this frenzy. Seems like this already kind of exists?

internetter2• 3 years ago

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.

modeless• 3 years ago

An entirely new category of superconductor could well be revolutionary even at this temperature, for several reasons. It could be the first one of a family with variants that go up to room temperature. It could be cheaper to produce or have other desirable properties for commercial applications. And it could lead to advances in theory that would allow prediction of other unknown superconductors.

brianpan• 3 years ago

This is not about 110K, this is about trying to verify the results related to LK-99.

The LK-99 that is room temp superconductive seems quite difficult to produce at this early stage. But these researchers were able to produce their not-as-good version of LK-99 and at least verify very close to superconductivity at 110K. This makes the LK-99 room temp superconductivity claims that much more plausible.

TillE• 3 years ago

Exactly. There are too many unknowns to draw any kind of real conclusions, but everything so far still supports a position of cautious optimism.

What we know is that LK-99 looks pretty interesting. Is it a room-temperature superconductor? Maybe!

belltaco• 3 years ago

First, at a minimum it validates that the researchers found a novel rare superconductor at ambient pressure, and are not frauds.

Second, the new mechanism of superconductivity may lead scientists to explore other materials with similar properties that may work better.

Third, the synthesis may not be completely spot on yet. It has been just 4 days of attempting replication, and this result is pretty good in that context.

kamranjon• 3 years ago

Is my understanding correct that 100k at ambient pressure is pretty special on its own?

downWidOutaFite2• 3 years ago

YBCO and BSCCO are superconductors around 100K at ambient pressure. Unfortunately their brittleness limits their practical use. Maybe LK-99 will have better mechanical properties.

mrandish• 3 years ago

For comparison, per this Wikipedia page (https://en.wikipedia.org/wiki/High-temperature_superconducti...) currently, the highest temperature, ambient pressure superconductor is around 138 K (−135 °C).

I'm no expert but based on my limited understanding, this result (if confirmed) while far from room temperature would still make LK99 a pretty interesting discovery in the SC world. And once a new SC like this is validated there are often methods discovered to improve the temperature or optimize other traits.

To me, the positive news here is that (if confirmed), at least LK99 isn't "nothing". Together with the recently released simulation studies indicating LK99 may have interesting SC-like properties, this causes me to increase my personal Bayesian SWAG estimate on LK99 (or a related descendant) eventually being a meaningful step toward room temp superconductors.

distortionfield2• 3 years ago

The doping agents used in synthesis seem like interesting pathways towards finding something more stable and reproducible in their cook

rwmj• 3 years ago

It's always interesting to discover a new class of materials that make high temperature superconductors even if they haven't discovered a room temp one.

gabesullice• 3 years ago

Agreed. Looking at the timeline on the Wikipedia page, a new 100K ambient pressure SC material is nothing to scoff at.

It means LK99 is about as good as the other materials, at minimum. However, its chemical composition is different than any of the other materials on the chart (i.e. it is lead based). That probably means there's lots to learn and new phenomena to be understood and optimized.

Furthermore, if this lab could achieve these results in a matter of weeks, perhaps labs with more exotic equipment and dedication will be able to get better results, raising the bar even higher.

jjallen3• 3 years ago

Exactly. These are literally the first attempts to replicate a poorly explained production process. Things are only going to get better over time as the materials increase in purity. These are other labs seeking publicity partly.

I for one think that this will turn out to be a major breakthrough based on the meta facts (decades of development for one) and not the actual science.

dr_zoidberg• 3 years ago

It means LK99 is about as good as the other materials, at minimum. However, its chemical composition is different than any of the other materials on the chart (i.e. it is lead based)

While what you say is correct, let's not forget that lead _is_ an elemental superconductor. With a Tc of 7K, it's only bested by niobium (9K) and diamond (11K) as an elemental superconductor.

Yes, cuprates and ceramics were ruling high-temperature SC so far, but it's not like lead was entirely unexpected in the superconducting world.

keyle• 3 years ago

In conclusion, we successfully synthesized the compound Pb10-xCux(PO4)6O, and observed the zero resistance above 100 K. However, the Meissner effect has not been observed yet in our samples, which suggests that the superconducting volume is relatively low.

In conclusion, ... nothing?

ayakang31415• 3 years ago

It's definitely something, rather big something, to observe zero resistance above 100k

awwkaw• 3 years ago

Not compared to the claim of zero restance up to 400 K.

But with how difficult the samples production seems to be, maybe we will get 400 K superconductors still

DistractionRect• 3 years ago

It's likely that impurities in the bulk of the sample are why we aren't seeing the Meissner effect. Seeing super conductivity though is extremely promising.

We've seen a sample be super conductors at 110k ambient pressure, diamagnetism, and (unconfirmed) flux pinning. So it's likely there's something here, but right now the main hurdle is synthesis. It's difficult to make and there's no clear path to consistency, purity or scale.

userbinator2• 3 years ago

I completely ignored the authors (as I usually do) and started reading it, noticed the slightly odd phrasing, and then chuckled at "mad great efforts" and then "a very excited news" a short while later before looking at the authors and realising the country of origin.

tomohelix2• 3 years ago

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 room temperature yet. But those kinds of experiments take time so it isn't an indicator of problem.

My take: It is probably something interesting but not well understood. Best case scenario, the original sample in the Korean lab probably won the synthesis lottery and is actually a true room temp superconductor. 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.

brucethemoose2• 3 years ago

Some literature suggests its a "one dimensiononal" superconductor only kinda works in tiny monocrystaline grains.

...But maybe thats even more interesting for, say, microelectronics? Especially if the resistance orthogonal to the superconductivity is high, if such a thing is even possible?

ThrowawayTestr• 3 years ago

Zero loss diodes seem pretty useful.

wbl2• 3 years ago

The really cute thing is conducting in one axis insulating in the other two. Then you get to have a very high density interconnect for free.

ibic2• 3 years ago

I think you are referring to the pioneer work done by Prof. Chair Tong-seek (or Dongsik Choi as another spelling) here? https://twitter.com/sanxiyn/status/1684437744406392833

Any Korean can give some brief summary over the book that tweets mentioned?

floxy• 3 years ago

The one-dimensional things seems like it could make it complicated to measure the resistance. Especially since the bulk material that seems like people are making isn't being laid down in thin films where you might know which direction the conductivity might go. What if there are superconducting grains/domains that abut to each other, but the 1-D paths are then not aligned? Even if you knew that the "domains" were aligned with each other, but didn't know the orientation, it seems like you'd measure a drop-off in resistance, but not to zero at the critical temperature. Maybe?

frognumber2• 3 years ago

Such things are possible, and not even very uncommon. The human body has tissues with conductivity different in different dimensions.

If you'd like to create one yourself, take a bunch of parallel insulated wires. Conductivity will be low along the wires, and high perpendicular to them.

Or alternated high-resistivity and low-resistivity sheets. Conduction will be low parallel to the sheets, and high going through them.

Lots of things behave like that.

pjc502• 3 years ago

An even better version of https://en.wikipedia.org/wiki/Anisotropic_conductive_film or "zebra tape", maybe.

jcranmer3• 3 years ago

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 that suggests otherwise is experimenter bias heaped on top of experimental error. 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.

46Bit2• 3 years ago

Agreed. Even the 100K zero-resistance claim isn't holding up to scrutiny https://nitter.net/condensed_the/status/1686895266329174016 https://nitter.net/condensed_the/status/1686901855358427136 https://nitter.net/condensed_the/status/1686832552252784641

throwawaymaths3• 3 years ago

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 fundamental reason for superconductivity in general to be impossible at RT.

tomohelix2• 3 years ago

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.

highwaylights2• 3 years ago

Waiting to see either way just like everyone else, but..

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.

.. really? You’re surprised by this?

blueprint2• 3 years ago

The worst case scenario is that there is actually nothing interesting with LK-99, and everything we've seen that suggests otherwise is experimenter bias heaped on top of experimental error.

well while we're one-upping each other I'm pretty sure the worst case scenario is some lk99 synthesizer actually creates a black hole which gobbles up the planet.

cthalupa5• 3 years ago

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.

There's plenty of people that are skeptical and making it a point to tell everyone they are skeptical. There's plenty of people that are skeptical that are still engaging on the possibility of it being real because it is interesting to do so. There are plenty of people discussing potential pitfalls in the papers being written and experiments being done.

But ultimately talking to people in the comments on HN is a form of entertainment for most of the people engaging, and skepticism is a lot less entertaining for most people in general than being enthusiastic and engaging on possibilities. It's not surprising that people going somewhere for engagement and entertainment are doing the thing that is more fun to the majority.

I doubt the majority of people that are excited about it would place serious money on it being true - I sure wouldn't. But I am having fun watching the developments, talking about things to the minimal extent I understand, and thinking about the Cool Stuff that would become possible if we were to suddenly have a new room temp ambient pressure semiconductor

jjallen3• 3 years ago

The reason I don't think this is the case is that they have literally been working on this thing for a quarter of a century. While the people involved are not full on superconductor experts, they are also not super stupid and realize that their claim is a huge one.

How could you work on something for years and years and years, make a claim that it is the first room temperature SC and be _totally_ wrong about it. Even if they only worked on it for ten years, I don't think they are totally wrong.

I think what has happened is that they rushed to publish the paper and the reason it has not been replicated is that they don't even know how to reliably make the material yet. This is why the methods to make it are not in the paper -- because they don't even know how to do it.

Remember they were forced to publish this paper by a rogue former employee.

Tade0• 3 years ago

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 plastered with LK-99 news.

doingtheiroming• 3 years ago

There’s plenty of skepticism. It’s the zero-cost position here. But there are good and bad skeptical positions. The good one involves people attempting to replicate and publishing results whether positive, negative or somewhere in between. The bad one consists of sitting in forums and threads being, “the voice of reason”.

If there’s a real problem, it’s that we have still not made publication of negative results sufficiently attractive. That’s still a problem throughout science and one we desperately need to address since it is what would let us think more clearly in situations like this.

DrBazza• 3 years ago

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.

HN is supposed to have a high signal-to-noise for comments. I'm skeptical about this. I think it's the modern Pons + Fleishmann, but I won't post that on every thread because it contributes nothing. There's more insightful, and interesting comments about chemistry than anything I can write that would add to the discussion.

SanderNL2• 3 years ago

It's good to keep an open mind both ways, but "skepticism" without either interesting or convincing arguments is IMO just as useless.

We all know there is a good chance it turns out to be a dud. We all know cold fusion/emdrive/superluminal experiments turned out to be duds. We all know this.

I wonder what news do "skeptics" have to bring to the table. Nothing a skeptic has to say changes anything. We are all - except for the handful of actual experts here - amateurs at best, but probably ignorant peasants. Just about anything we have to say about it is just noise. I'd favor the positive noise, but that's just me.

Imagine being at a football game: "This game could easily be lost! Ah, see, another pass failed. Don't get your hopes up! Please don't cheer, please wait until the very last moment and then wait another hour to have administrative confirmation. Then wait two weeks. Then you may cheer, but only modestly."

23B1• 3 years ago

We skeptics have just grown tired of arguing (with everyone, on everything, all of the time)

stephencanon• 3 years ago

Why would skeptics waste their time commenting on LK-99 threads? There are much better things to do.

stonemetal12• 3 years ago

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 a near freezing repro so I have grown more skeptical of the original claim.

TheRealPomax• 3 years ago

I'd go one step further. The worst case is they made up data enough to seem plausible, knowing full well replication is impossible, but their institution wanted their name in a major publication so they were told to make shit up and get published.

s0rce• 3 years ago

Most papers are so bad its nearly impossible to replicate the synthesis.

adrian_b6• 3 years ago

Not this one, which has a very detailed description of the synthesis, including what has worked and what has failed.

fnordpiglet• 3 years ago

I’d note they claimed to try the synthesis over 1000 times to arrive at their best sample. They admit to not being physicists and being more experimental chemists. If there is anything here, which at minimum seems they’ve found something interesting. The theoretic research published recently supporting their claims coupled with the discussion that the apparently superconducting material is less likely to form it’s probably (IMO, IANAP) a process that requires substantial refinement but holds a claimed experimental and theoretically demonstrated potential to be a room temperature normal pressure superconductor as claimed. There seems to be a lot of “their work is sloppy” and “their method isn’t refined” as a proof of a negative, but it’s just proof that science is done in many ways by many techniques and no one is sufficient, but everyone is necessary.

kuprel• 3 years ago

Why don't they just share the original sample? At least it could offer an existence proof

xvector• 3 years ago

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.

adrian_b6• 3 years ago

While the production method of the original Korean authors is poorly documented, the synthesis method used for this paper is described in a very detailed way, also mentioning a few alternative steps that have been tried, but which caused failures in obtaining the desired structure.

While their synthesis method works very well for something improvised in a couple of days, it requires significant improvements, because the samples are very inhomogeneous, which greatly complicates the measurements and the interpretation of the results.

I believe that the properties of this material will not be completely elucidated until someone grows a monocrystal of it, but developing a process for this might take months, if not years.

jjallen3• 3 years ago

What is this supposed to be a summary of? The temperature at which this team observed zero resistivity was much much colder than room temp.

reacharavindh• 3 years ago

With my conspiracy theory hat on, perhaps the authors were encouraged/coerced to not release proper documentation to reproduce the recipe entirely by [their bosses, state agencies etc.] If the claims are true, then the implications to defense, weaponry and such are very high, and the C|N|D* agencies like to not lose their cards in the game.. /conspiracy

Real science is just darned difficult, and the scientists are working hard to reproduce the results themselves. Which is more likely.

_ph_3• 3 years ago

Right. From my own experience, growing crystals is close to alchemy. Of course we know exactly how to do it, yet, it takes a lot of skill to grow a lot of substances. There are a lot of detaills to the process which are difficult to capture in documentation, even if the best faith attempts are made. Add to that any variation in the machinery used. As a consequence, it is quite common in crytallography that there is a single source for certain crytals. At least in an initial phase. If a substance becomes reasonably popular, eventually more people manage to produce quality crystals.

So I would expect eventually good samples to turn up elsewhere as many groups are working on this, but it can take a lot of time. Especially as no one knows what exactly was different about the Korean samples.

sampo• 3 years ago

The production method is so poorly documented only a fraction of the samples being made shows any interesting properties.

I have understood that rather, the production method is poorly known even to the Koreans themselves, and also they have only a small success rate in their samples. So it's more that the Koreans themselves are not entirely sure what "makes it click", and you can't document it well because you don't yourself know all the details.

TylerE• 3 years ago

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.

sedatk2• 3 years ago

Off-topic, but I admire the effort to translate the formula to Unicode characters in the title. It's not just a simple copy-paste from the article.

Arnavion2• 3 years ago

The submitter also fixed the incorrect use of the degree symbol before K, lol.

8n4vidtmkvmk• 3 years ago

"degrees Kelvin" is wrong? Why's that?

LightMachine2• 3 years ago

GPT-4 does it very well though. (Not saying OP used it, was just curious if that'd work.)

Prompt:

Observation of zero resistance above 100∘ K in Pb10−xCux(PO4)6O
convert this to a title, with the correct usage of unicode

Output:

Observation of Zero Resistance Above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O

sedatk2• 3 years ago

Wow, I would've never thought to use ChatGPT for this. Very cool.

1letterunixname• 3 years ago

ChatGPT says:

    The chemical formula "Pb10−xCux(PO4)6O" can be written in Unicode as follows:

    Pb₁₀₋ₓCuₓ(PO₄)₆O

    Please note that not all characters may be perfectly aligned due to font 
    variations and rendering differences in different systems. However, this 
    representation should provide a close approximation to the chemical formula.

As plain text: Pb₁₀₋ₓCuₓ(PO₄)₆O

EDIT: Note that arxiv uses mathjax (JS) to take a compound formula as plain text and applies subscript, superscript, etc. styling to it. ("Pb10−xCux(PO4)6O")

moralestapia• 3 years ago

I really really wanted this to be true just so we can all take a look at how much wrong some things are in academia and science nowadays.

Plenty of "knowledgeable" people and research groups put out a lot of discrediting (and actually ignorant) statements about this, a lot of them with a dash of xenophobia in the mix.

Congrats to the people that actually push science forwards!

Haters gonna hate but no one will remmeber them, ever.

Waterluvian2• 3 years ago

I don’t understand the physics, but it feels like a truly zero resistance conductor would violate some law of thermodynamics or something.

Is a superconductor truly zero impedence or just very very very low? Because I’m seeing a lot of these graphs with something like: “0.00001ohm” as the y-axis floor.

ramraj072• 3 years ago

MRI machines work using superconducting magnets as does the LHC. So you better believe it buddy.

Waterluvian2• 3 years ago

Why do MRIs need zero resistance vs incredibly low resistance?

distortionfield2• 3 years ago

It doesn’t though, that’s what’s so tantalizing about it. It’s counterintuitive but as I understand it, the current best theory of superconductor behavior properly conserves mass and energy and the math says a room temperature one should be perfectly possible. It’s just not been found. And yes, it’s truly zero resistance as far as we understand the concept of “resistance”.

yongjik2• 3 years ago

Not an answer, but if you think superconductor is weird, look up superfluid, now that's going to make your head spin.

LightMachine2• 3 years ago

why there are no good videos of superfluids in action in the whole internet?

555552• 3 years ago

Thanks for the interesting new thing. If they suffer no loss in kinetic energy and a wave can move forever, could we use a circular pool of superfluid as an an energy storage mechanism?

alex_suzuki• 3 years ago

Superfluids have been around for ages - we call them beers.

marcosdumay5• 3 years ago

The electrons are always moving in some direction. What a superconductor does is "just" making an electron pull others with it, making a cascade effect that biases the movement permanently.

There is no work or state change, so no reason at all to conflict with the 2nd law of thermodynamics.

klyrs• 3 years ago

Key point, resistance is the real part of impedance. The imaginary part, or inductance and capacitance, are not zero in a superconductor.

_ph_3• 3 years ago

Yes, as others already said, superconductors are zero resistance. Which is easy to check if you have enough of the substance to run meaninful currents through it. There might be miniscule amounts of resistance for contacting and impurities, but the resistance doesn't grow e.g. with wire length.

So how is this possible? The explanation is acutally reasonably easy, but requires the strangeness of quantum dynamics. One basic principle of quantum dynamics is, that at least most things are quantisized. Especially energy of a state comes in discrete amounts. That is the reason we have orbitals of electrons in atoms. They can only take very specific values, which creates these separate orbitals. There is no in between state, they have always to absorb or emit exactly the amount of energy which is the difference between orbitals when moving between them. Which is a very easy effect to literally see: take glowing phosphors as you find them on your watch etc. These are transitions bound to a specific photon energy. With red light, you cannot "charge" them, as red photons have to little energy, and you can only absorb single photons. Any green or blue light would work though. And whatever light you used to "charge" them, they always glow in the precise same color, coming from their destinct energy state.

The resistance an electron encounters while moving through a conductor is also quantisized. In superconductors we have a situation like trying to charge a watch dial with red light: the amounts of energy an electron could release cannot be absorbed by the material. And an interaction would require this. The consequence is: no interaction, no resistance.

The situation is like trying to buy a $1 bottle of water with a $100 bill. That could turn out to be impossible, because no one is willing to give you back $99, and you can of course not pay $100 for the bottle. So even when having the money, you can't buy the bottle.

This is, in a very naive way, the principle how superconductivity and superfluidity work. The trick now is to prepare the conditions which allow for superconductivity. One way is to make things increadibly cold. All metals become superconductive, if the temperature is close enough to 0. But that is with single digit degrees or below, even fractions of a Kelvin. Konsequently it was a huge sensation when the first complex substance was presented which showed the effect at larger temperatures. Since then the hunt is up to find better substances.

Jyaif• 3 years ago

Fascinating.

Let me get this straight: If you have a piece of phosphor, you can't heat it up with red light, regardless of the amount of red light you shine at it? If so, does the red light bounce off? Go straight through?

daxfohl2• 3 years ago

Similar to how a magnet works. A magnet can hold something forever, so seems like a violation of thermodynamics. But "holding" isn't work, it's just force. (Which is still kinda spooky, admittedly) Similarly, conducting itself isn't work, it's just conduction.

huthuthike• 3 years ago

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.

thehappypm• 3 years ago

Ask yourself this question: Why does resistance occur at all? Why is it that electrons moving through a material cause them to heat up? What is actually happening to cause that?

At micro levels, like molecules bouncing around in a gas, collisions are lossless. What makes electrons moving through materials different?

jcranmer3• 3 years ago

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 also demonstrated that the critical temperature varies with applied magnetic field. Here... there's no apparent variation in apparent critical temperature.

I'm sorry, but this result just feels to me like people are assuming that the material must be a superconductor and are analyzing all the data under that assumption rather than asking the question "is this a superconductor?"

evancox1002• 3 years ago

Not a superconductor expert, but resistance exponentially decreasing with temperature is not a normal phenomenon in most cases!

bandrami2• 3 years ago

Most semiconductors have a thermal regime where that happens, it's just a relatively small regime, I thought?

46Bit2• 3 years ago

https://nitter.net/condensed_the/status/1686895266329174016 claims a linear representation of the same data. Still no convincing discontinuity visible.

IsTom• 3 years ago

Makes the dip around 250K even more visible.

segfaultbuserr8• 3 years ago

The log-scale here complicates my intuition

Logarithmic plots are a device of the devil. - Charles Richter

Klaus23• 3 years ago

The gradual drop could be the result of a mixed sample where different parts of the material show superconductivity at different temperatures. As more of the sample becomes superconducting, the resistance will gradually decrease until a superconducting path is created between the probes and the resistance reaches zero.

adamsmith1432• 3 years ago

The proposed mechanism for superconductivity in lk-99 is pretty different so that may be confounding your interpretation of those graphs.

gilbetron• 3 years ago

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.

superposeur2• 3 years ago

Question for the cognoscenti: supposing that LK-99 superconducts with T_c = 110 K, how significant a discovery would this be? I.e., does it establish a brand new class of high-T superconductors, or is it merely one unremarkable member of a known class? Further, does it offer advantages over other high-T superconductors such as ease of fabrication or cost?

cthalupa5• 3 years ago

It's a brand new class.

The material cost is lower than most superconductors - it's lead and copper - but no one has any idea on fabrication, yield size, etc., now, so no good answers there.

superposeur2• 3 years ago

Thanks.

scheme271• 3 years ago

To add to the other reply, it'd be a new class especially since it would be at standard pressure. I think the current highest Tc SC at standard pressure is at much lower temperatures. Frankly, there's probably a lot that you can do with a superconductor that you can cool with liquid nitrogen even if it can't carry much current or handle high magnetic fields. Moving from liquid helium cooling to liquid nitrogen alone significantly reduces the cost and complexity of your cooling system.

AnnikaL• 3 years ago

Don't YBCO superconductors already work at liquid nitrogen temperatures?

ibic2• 3 years ago

So this almost means the holy grail has been found or we are pretty close?

gandik• 3 years ago

This is so reminiscent of what happened after Fleischmann & Pons. Labs attempting to replicate saw this property, or that property, but never the whole, unequivocal picture.

Here we have a room temperature superconductor that isn't a superconductor at room temperature. A sample that has no measured Meissner Effect at any temperature. And the authors admit that some (many?) of the samples tested out as semiconductors.

Also, they don't happen to mention how they measured resistance. 1mA current, yes, but what equipment? And what setup? Micro-measurement of resistance is hard. We really need to know more about that.

rsfern3• 3 years ago

I agree with your first points, but the methods section states (somewhat unclearly) that they used this 4 point probe setup

https://www.qdusa.com/products/ppms.html

I have more questions about that, like why not calculate sheet resistivity instead of just showing that the resistance hits the noise floor?

segfaultbuserr8• 3 years ago

I agree that the setup is not satisfactorily documented.

but what equipment?

But at least this individual question is actually included in the paper. It was the Physical Property Measurement System (PPMS), manufactured by Quantum Design Inc. From the photo, one can clearly see that the DC resistance test fixture was used.

https://www.qdusa.com/products/ppms.html

highwaylights2• 3 years ago

I see. So what you’re saying is that if we replace the palladium with LK-99 then cold fusion is back on?

You know, because hype.

This is, as the kids say, very bullish.

hindsightbias• 3 years ago

I’d be happy if it just makes UFOs in focus.

carabiner• 3 years ago

I read more about F&P and wow, there are striking similarities. The duo probably weren't fraudsters. No intentional deception in their work was ever found, so not like Hendrik Schon. They were basically forced to make their results public by their university, but it was very premature and they should have waited ten years. They were 100% legit, top researchers in the field before all this, and well after the scandal many scientists continued research in avenues initiated by F&P's original experiments (with little success). I can totally see LK-99, once it fails replication in a month, leading to more research but probably not yielding the holy grail.

crote3• 3 years ago

To me the biggest difference is the three theoretical papers, including from very reputable sources, all showing that a) there is indeed something weird going on with this material and b) due to the unusual configuration it is going to be tricky to manufacture.

Fleischmann & Pons was never supported by theory and was essentially a "we measured something and have no idea what is going on". LK-99 is more of a "the theory says something interesting will probably happen, and we believe we measured it in some samples but can't reliably reproduce it".

progrus2• 3 years ago

It’s real, it works, the Navy has a linked patent from 2017.

The UFOs are a PSYOP.

declan_roberts• 3 years ago

The Navy does have a patent for a “lead zirconate titanate” super conductor which does sound awfully similar to what’s described in LK-99.

https://phys.org/news/2019-02-navy-patent-room-temperature-s...

progrus2• 3 years ago

Ding ding.

FrustratedMonky2• 3 years ago

Man. I hope it isn't. That would be sad, all this was happening, and nobody had found the old study. Surely not.

unsupp0rted• 3 years ago

The application claims that a room-temperature superconductor can be built using a wire with an insulator core and an aluminum PZT (lead zirconate titanate) coating deposited by vacuum evaporation with a thickness of the London penetration depth and polarized after deposition.
An electromagnetic coil is circumferentially positioned around the coating such that when the coil is activated with a pulsed current, a non-linear vibration is induced, enabling room temperature superconductivity.

drtgh• 3 years ago

From the same author https://doi.org/10.2514/6.2019-0869 , 2019 Salvatore Cezar Pais

It is important for the PZT coating to undergo a polarizing (poling) treatment prior to RTSC enablement, so that optimal domain alignment is obtained within the ceramic coating, by subjecting the coating to a strong dc current electric field, slightly below the Curie temperature (approx.200 0C, but possibly as high as 360 0C, depending on PZT ceramic composition). Furthermore, to increase the probability of vibration in one particular direction, as well as to alleviate the brittle nature of the ceramic material, it may be necessary to make the 'metallic' wire coating out of a composite PZT and highly conductive polymer, such as p-Terphenyl [4]. Another option is to sandwich the PZT ceramic in between two layers of aluminum, resulting in a wire design which may be planar rather than cylindrical in nature. This composite coating design would amplify piezoelectrically-induced vibrations and possibly render them unidirectional.

From LK99 rumors:

At the beginning of 2020, Ji-Hoon Kim continued to do experiments as usual, suddenly he found a huge peak, he repeated the test + looked at his notes. But didn't find any special points. He started looking through the lab videos. He finally realized that the tube of sample came out with cracks on the quartz tube, and he hit his elbow on the table while transferring the sample out to the electronic scale. Introducing oxygen at the right moment + a violent impact would change the structure of the lead apatite crystals being formed.

May be something, may be nothing,

S.C.Pais: "to increase the probability of vibration in one particular direction"

S.C.Pais: "piezoelectrically-induced vibrations [ and possibly render them unidirectional]"

LK99: "oxygen at the right moment + violent impact would change the structure of the lead apatite crystals being formed"

adrian_b6• 3 years ago

Except for the fact that both materials contain lead, there is no resemblance.

Lead is one of the best superconductors among pure metals, whose superconductivity has been already discovered 110 years ago, in 1913.

Nevertheless, there is absolutely no relationship between the superconductivity of pure lead and the alleged superconductivity of lead zirconate titanate and the alleged superconductivity of lead phosphate doped with copper.

They have very different crystal structures and behaviors of the free electrons (i.e. electronic band structures).

Only if in the PZT samples used by the Navy there would have been some impurities, without the knowledge of the researchers, causing contraction of the crystal when substituting the big lead atoms, then there would have been a similar mechanism to what is claimed now.

If this mechanism is proven to really work, then it could also work in other crystals with big ions, like lead or baryum, perhaps even in PZT.

MichaelMoser1232• 3 years ago

LK-99 contains polonium? which has a half-life of hundred and something days.

redox99• 3 years ago

Lol. Polonium is Po. PO is phosphorus and oxygen.

MichaelMoser1232• 3 years ago

thanks!

EvgeniyZh• 3 years ago

Note that there is no signs of phase transition (no jump) and the values below 110K are around reasonable measurement resolution. It may be that they just got the resolution threshold and misinterpret it as SC

pyeri• 3 years ago

As a lay person not graduated in STEM subjects, can someone ELIFY how is this research useful to society?

beanjuice• 3 years ago

This exact paper is the newest progress on recent hype regarding a semi-trustworthy not-peer-reviewed study claiming 'superconductors at room temperature'.

'Superconductors at room temperature' are cool because they would answer questions like "How would we get solar power from [your local desert] everywhere else for free?" and "How are we going to use MRIs when the helium runs out?" as two examples.

elromulous2• 3 years ago

ELI5, if these folks confirmed zero resistance at room temp and atmospheric pressure, isn't that confirmation of the original paper?

Edit: I read 100 K as 100°c. Mea culpa.

mcqueenjordan2• 3 years ago

100 degrees kelvin is about 338 degrees Fahrenheit below room temperature.

elromulous2• 3 years ago

Duh. Thanks. I think my brain must have transposed that K to C.

matsemann• 3 years ago

Thanks for making it even more confusing by introducing Fahrenheit, haha. ;)

anonymousDan• 3 years ago

Can someone point me to a list of exciting applications of room temperature superconductors? Trying to understand why such excitement about this!

tetris11• 3 years ago

https://en.m.wikipedia.org/wiki/Technological_applications_o...

febusravenga• 3 years ago

I see lead (Pb...something) as main ingredient, isn't it banned in most industries because how toxic it is and how hard it's to handle in industrial scale? isn't that a problem for potential mass applications?

(lots of comments about this discovery call this revolution that will change everything around us and that somehow implies mass production I guess)

thomasmg• 3 years ago

Lead is still used for example in car batteries (lead-acid), bullets, and solders (electronic components).

cycrutchfield• 3 years ago

Airplane fuel...

pjc502• 3 years ago

It's banned in the EU under RoHS .. but with a whole load of exemptions, which make it kind of pointless. I suspect this would be exempted pretty quickly once it became important.

kolinko2• 3 years ago

A high chance that lead can be replaced with other metal, from what I heard.

Also, it’s not extremely toxic - romans ate from lead dishes and didn’t even notice the toxicity.

You don’t want to consume it, and you don’t want to breathe it, but it’s not as bad as say, asbestos.

If you have an ICE car, it probably has a lead-acid battery, and the only thing that prevents us from using lead in grid storage is their short lifespan - not health or ecology :)

Also, if you ever took an x-ray, you wore a lead jacket to prevent unnecessary radiation.

If we cannot avoid lead in this alleged superconductor, it may limit applications slightly, but not by much.

yreg4• 3 years ago

Tesla has a lead-acid 12V battery as well :)

gtsteve• 3 years ago

If this discovery is confirmed then someone will figure out how to do this safely, using robots or other kinds of machines to produce superconductor wires. The benefit derived would be simply too great to ignore it. Perhaps superconductors don't show up in your home but I can certainly imagine applications in optimising power grids.

ur-whale• 3 years ago

And now for a slightly different take on the much-discussed room temp. superconductors:

on the off chance that this LK-99 stuff is actually going to be a thing, how should that influence my investment portfolio over the course of the next five years?

Should I buy lead mining stock ?(joke, obviously, but you get the point).

dougmwne• 3 years ago

It would bias our energy markets towards electric and away from fossil fuels. But due to climate change, there’s already a lot of pressure to go in this direction.

hamilyon22• 3 years ago

Why is western mass media silent? They always pick up emerging stories like that, but not in this case for some reason

crote3• 3 years ago

Western media isn't silent. It has been showing up in the science section of mainstream media for a few days now, with a healthy dose of skepticism around it.

It's in the New York Post, on CNET, on CNBC, the Washington Post, Wired, New Scientist, Popular Mechanics, and plenty more. Just because CNN isn't covering it 24/7 doesn't mean the western mass media is "silent".

hamilyon22• 3 years ago

Good to know. So it means that the particular subset of media I am paying attention is silent. Thank you for the correction

daemontus2• 3 years ago

I see a lot of "This must be real, why would labs publish this if they don't think it's real, they have nothing to gain." sentiment on HN lately. Or "Researcher's career would be ruined if they falsely claim to replicate.", and so on. I also want to believe! But I should add a bit of skepticism to the hype :)

- "this could ruin their career": Depends. If they posted completely fake numbers or intentionally fake videos. Sure, that would be bad. But none of this is peer reviewed, and all of this can be retracted. A contaminated sample? Oops, retract. Bad measurement methodology? Oops, retract. Sure, somebody will remember that you made the controversial paper in the first place, but as long as you are not provably fabricating, a lot can be attributed to "an honest error". There are tons of peer reviewed papers out there with errors that completely change the outcome. Does not mean the authors are "finished".

- "they have nothing to gain": Oh, they absolutely do. While "science should be fully objective", funding agencies very much aren't. Obviously, just like VC funding, science funding is not a complete coin toss. But having "the right" team and background is often as important as the idea itself. One way to get the right background is to "touch shoulders with the giants" and one way to get the right team is to be highly visible and attract talent.

So overall, if LK99 is eventually shown to be a superconductor by someone else, you have a lot to gain, even if your own initial study is not perfect.

Let's say your team synthesised something. It looks like LK99 and it has some properties that are not really superconducting but at least a bit unusual. This clearly isn't what you hoped for. Now, do you run a bunch of other controls to see if it is some form of contamination, process error, combination of both... or do you publish a vague click-bait paper on ArXiv and hope that other results will somewhat align with yours?

Finally, I'm not claiming this paper or any other paper intentionally published untrue or misleading results. Just that scientists are also people. They have FOMO, they follow trends, they see what they want to see. As always, big claims require big evidence, and so far we don't really have that. But that does not mean there isn't some truth to the big claims :)

jpambrun2• 3 years ago

A contaminated sample that materially change the composition but still yield a superconductor would be a novel finding.

An error in manipulation leading to an external communication on something this high profile is sure to affect your career. It's like a biologist claiming to have found evidence extraterrestrial life and having to retract. I think I would consider hara-kiri..

daemontus2• 3 years ago

But the thing is... except for the original authors, none of these papers so far really claim to have a room-temperature superconductor, right? They claim "simulated band structure with low Fermi level", or "unusual levels of diamagnetism", or "almost zero resistance up to -100°C (but lack of phase transition)", etc.

Yes, retracting these is still shameful, but it's not a "we found extraterrestrial life" claim. It's a "we received weird signals from a nebula that we don't understand so far" claim.

And yes, a lot of supporting but inconclusive evidence is still supporting evidence. My point is not that (most) scientists would risk lying about replicating a superconductor, but rather that uncertain or inconclusive results with a solid chunk of plausible deniability in a rapidly evolving environment go a long way towards being "in the room where it happened".

JoeAltmaier• 3 years ago

Reliable production of the material is an engineering problem. If it can just be shown to work once, then the goal will be to mass-produce it in useful forms and structures.

Replication has been partially successful, exhibiting remarkable new results that are already worth celebrating.

ajnin• 3 years ago

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 one year later and it will still be there". Exponential decay will quickly catch up with a non-zero value, even very very small. Still this exponentially decreasing resistivity looks interesting, I have no idea if that's unusual or if that means anything. The weird dip at around 230K will need to be explained as well. I'm just an interested bystander, that goes without saying.

Sharlin• 3 years ago

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 does and then suddenly stabilized to some very small but nonzero value… That would probably require entirely new physics to explain and would be a much bigger news than "merely" a 110K Tc superconductor!

foven• 3 years ago

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.

Loughla• 3 years ago

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?

segfaultbuserr8• 3 years ago

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.

boringuser2• 3 years ago

The most compelling evidence offered thus far is from actual scientists that have reviewed the LK-99 paper and determined the scientists involved aren't very good at science.

nmca• 3 years ago

I wish we had real money prediction markets. Afaict it would be legal to run such a business in the UK.

parineum• 3 years ago

I remember seeing something like this that ran on bitcoin a while ago. It was completely user driven and lines were dynamically calculated by the action. I'm not sure how the resolutions to the bets were determined exactly, perhaps there was a requirement of a third party indicator of some sort, I don't recall.

wwarner• 3 years ago

Here's Brian Keating interviewing Jorge Hirsch from UC San Diego and Inna Vishik of UC Davis [0]. Prof Hirsch was/is a leading critic of the U Rochester papers, but thinks that LK-99 could work.

[0] https://www.youtube.com/watch?v=qQnDatnAWP4

mmastrac• 3 years ago

I'm impressed that Pb₁₀₋ₓCuₓ(PO₄)₆O is completely representable in Unicode.

hcks• 3 years ago

- it’s an easy to make room temperature superconductor!

- ok it’s hard to make but still RTSC!

- ok it’s superconducting at 100K but its a novel class of SC! <= you are here

- ok it’s not a superconductor but it still has interesting properties!

- ok it doesn’t have singular properties but it could have!

I predict there will still be LK99 truthers in 20 years arguing that this amazing discovery was buried by big copper conspiracy.

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

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