Why scientists are so skeptical of the LK-99 room temperature ambient pressure superconductor

hi everyone welcome back to the channel so  the internet is absolutely ablaze with this   new potential discovery of a room temperature  ambient pressure superconductor reported by   one South Korean group but there's two papers  that were released on the archive in July 22.   since then basically there's been a huge number of  news reports going on about how this thing could   be a novel superconductor the consequences  in terms of the new technologies things like   superconducting stocks in Korea have been going  through the roof in the New York Times there's   been a new report this morning about how LK 99  is the new ambient superconductor of the summer   and of course on Twitter there's been like all  kinds of people weighing in about whether this   is a new superconductor or not there's even been  a twitch Channel which has been live streaming   their experiment in replicating this this new LK  99 synthesizing it and then seeing whether they're   superconductivity or not of course there's been  all kinds of weird memes and things like that with   fake reports of people verifying LK 99 this one  is a supposed verification with basically a coin   and a piece of fishing line memes about how this  is the new chat GPT people anxiously waiting for   new results on verifications and of course now  everybody is an absolute superconductor expert   right this in the scientific Community has been  met with quite a lot of skepticism so this is a   very early tweet that Sankar das Sarma made just  about two or three days after the initial papers   were put on the archive and already at this point  people were skeptical if I just read out the Tweet   he basically says that he's a another claim of  room temperature superconductivity and levitation   by another relatively unknown group with limited  background in superconductivity in fact they make   two bold claims in one evening obviously this is  unlikely but the boldness is breathtaking I really   like the way that he phrases this given this kind  of backdrop I just what I want to do today in   this video is just to give you a little bit of a  sense of why the scientific Community is skeptical   about it and basically let's see whether this we  really have any hope that this will be really the   Breakthrough that it promises to be okay the thing  about this paper is that apart from the kind of   the weird sort of writing there's all kinds of  peripheral things which raises a few red flags   even before you really start to delve into the  paper right if you look at the lead researchers in   the paper they come from this place called Qcentre  in Korea but actually if you go to the website you   can't actually get there anymore I don't know it's  being shut down it's a bit mysterious in itself oh   yeah it could be hacked with the intense pressure  yeah it could be anything right but so about a   week ago there was a another the video by Dave  Jones from EEVblog I don't know you guys might   be familiar with it at this point when he made  this video this website was still up right and   what you can gather from this website is that it's  some kind of startup or some kind of commercial   company rather than a research institution or  a university and basically what Dave does in   this particular video is to debunk a particular  demonstration of this material which I think that   this company is basically trying to sell you  know this is basically their product and the   video involves basically a piece of this material  hanging from some fishing line and then they get a   different magnet and then they like oscillate this  magnet near this piece when I saw this video for   the first time I also thought it's a bit weird I  didn't really know what to to make of it actually   is this supposed to show superconductivity or  something maybe navigation yeah it's definitely   yeah it's not really levitating is it it's like  a string so it's yeah exactly but basically what   Dave does in his video is that he basically  replicates the same kind of experiment with   a piece of copper and then this silver thing  here is some magnet it's a weird shape but   it's basically just the magnet and basically you  can do the same thing and he just says this is   just Lenz's law like you learn in high school it  debunks that part well it's a bit mysterious what   that demonstration was supposed to show but anyway  the website's taken down regardless another weird   kind of thing which people have already talked  about a bit is that apparently the reason why   there's these two papers is that this last author  on the three author paper actually submitted it   without the permission of the other two authors  that's also another very weird circumstance which   normally does not happen and presumably they knew  about this because these two papers appeared on   the archive kind of at the same time right so they  probably knew that this guy was going to submit or   something and then then they made sure that they  also had their version up on the archive like on   the same day so weird circumstances another weird  thing is that they've had this material since 1999   this is what the 99 stands for in the name of  the material they've had 20 years to basically   perfect this material and investigate it and  I'm sure it's not you know they just turned   around this year and then figured out that it's  you know a superconductor you know they've been   playing around with this for for probably decades  and considering this thing is a fairly easily   manufactured material and people are just like  doing this in real time on Twitch manufacturing   this stuff and actually measuring its properties  it's a bit weird that all this is coming out right   now another reason why people are very skeptical  about this is that there's been lots of room   temperature superconductivity claims in the past  and one particularly notorious case was this case   by Range Dias back in 2020 he along with his team  claimed that there was a material that possessed   room temperature superconductivity obviously this  paper as you can see here has been retracted now   this came to be retracted because this guy Hirsch  as famous from the Hirsch index the same guy he   actually went after this group to show that  basically there's something wrong with their   results and in the end basically they were forced  to retract their results but what's interesting   is that even in this retracted paper their claims  are not even as profound as basically what's being   planned right now with this LK 99 right so if  you look at the claims there it's temperatures   of around 15 degrees Celsius that's slightly  like a cold room and 267 gigapascals that's 10   000 times the pressure of ambient pressure  right even these well we now believe to be   faked results are actually quite modest compared  to the results that are being claimed right now   now that doesn't really mean anything really it  but this really would be such a massive advance   in comparison to what's available out there  at the moment that's basically some kind of   peripheral information that you just want to have  in your mind just incidentally this yes guy also   published another paper just earlier this year  also of room temperature superconductivity again   at again very high pressures right so this was  accepted into nature presumably people looking   at this also with quite an eye of skepticism but  what's interesting even to look at the results   from this retracted article is that there's some  key signals of superconductivity if you're going   to claim room temperature superconductivity  then there are some sort of key things that you   probably need in order to get it through to Nature  and one of the key things is of course measuring   zero resistance and even in this retracted article  there is like this kind of plot here on the left   where you see the resistance on the vertical axis  and the temperature on the horizontal axis is and   basically at some temperature it collapses to zero  this is the classic Hallmark of superconductivity   this is what honest saw back in 1911 with Mercury  and this is still basically the classic signal   that you really want to see you look at the  results of of the paper it's just weird there   is a plot like this this is in the sixth author  paper so there's a plot of the resistivity against   the temperature and indeed there is this drop  that happens at 110 degrees Celsius not Kelvin   but Celsius so this is like above boiling point of  water but it doesn't really drop to zero right and   it drops to some value which is it looks like  about Point yeah 0.2 times 10 to the minus 2   ohm centimeters and so if you compare this to the  resistivity of say copper this is like way higher   right it's way higher it's resistivity of copper  is 10 to the minus six in the same units right so   this is is like 10 to the minus 3 versus this is  10 to the minus 6. if you just look at that you'd   say yeah it's not really of course this later on  goes down to smaller values but the scale is so   big you can't really see what value this is really  going to it's looking at something on a huge scale   when you really want to see the small values right  so that's a weird aspect of this really can't make   heads or tails about it from the three author  paper they don't have this classic resistance   versus temperature plot or resistivity but they  do have the one graph that they do show about   the resistivity is this one where basically they  show essentially at one particular temperature I   presume of the voltage versus the current and then  so from that you can work out the resistance and   apparently from this larger plot they work out  the smaller plot and I assume they do something   like this and this is just my naive first year  physics kind of method here but if you work out   based the resistance of this because V equals IR  right so resistance is V divided by I okay so you   for example take one of these points here let's  say it's about 0.1 micro volts let's say roughly   and this is 25 milliamps okay and so that will  give you a resistance of about 10 to the minus 6   ohms okay and now to convert this into resistivity  we need to multiply by the dimensional Factor like   how big this sample is now again they don't really  tell you exactly the sample size in that paper   but in the sixth author paper they do taking the  sample to be this Dimension and then calculating   this A/L you get a resistivity of something like  10 to the minus 7 ohms centimeters okay now that   is not really the same value that you you get in  this graph right that you're getting something   like 10 to the minus more 10 right so there's  three orders of magnitude shoot missing unless   I've done something stupid here you can tell me  in the comments if this was all wrong but I'm   not sure even how they can get these values of the  resistivity okay obviously people have been trying   to replicate these results and so far as for the  resistance estimate I think this is the closest   that people have come this is a very quick results  coming from Southeast University that came out on   the 2nd of August and they basically managed to  measure a zero resistance but they could not do   it at room temperature they need to go down  to something like 110 Kelvin in order to see   the resistance dropping to zero so basically the  graph on the left here is the results in at some   temperature around 110 the resistance basically  goes to somewhere in the noise right but even   this is being criticized quite a lot because this  graph doesn't really have the classic shape of   superconductivity what you'd expect so if you  replay that same graph on a linear scale then   it has this kind of more like curved dependence  not like this sudden drop and generally phase   transitions have an extremely sudden drop that  goes to zero because it's like when ice turns   into water it's a very sharp transition it's not  like ice turns into water roughly in the range   of -20 to 20. it exactly at zero is the phase  transition point and phase transitions tend to   have this very sharp behavior and the only sharp  behavior that you see here is around here at about   230 Kelvin but this clearly looks like some kind  of experimental artifact so going back to dasama's   tweets here he's very scaling of these results  that are coming out from Southeast University in   inverted commas he says physics being presented  in these unreferied preprints is a travesty the   original paper has no obvious superconducting  transition and the T < TC resistivity   is a hundred times that of copper original so  known as Southeast also has no transition just   instrumental artifacts that's this sort of weird  drop that you're seeing at 200 and odd Kelvin   what is the goal here no one can fool nature very  scathing of basically both of these reports right   now onto the Meissner effect this effect of  the superconductor kind of floating is one of   the classic signals of superconductivity it's  the effect that superconductors can expel all   magnetic fields from within them and so this is  why you have this levitation kind of effect right   there's been also another follow-up video just  this morning posted on the New York Times and   they have basically a similar type of video again  it's sort of floating but not entirely floating   with one Edge on the side in terms of replication  maybe the closest to any kind of replication has   come from another Chinese group from the Hangzhou  University of Science and Technology and they   posted their video on BiliBili and they showed  my tiny fragments of this stuff again showing   this semi-levitation kind of effect right but the  thing with this kind of levitation effect is that   and this is the criticism that a lot of people are  pointing out is that basic basically this effect   is diamagnetism and diamagnetism basically means  that it's a material that follows the magnetic   field in the opposite way right a lot of materials  that we're familiar with like iron are usually   paramagnets right so your fridge magnet that you  stick on your fridge if you put it on there the   reason why it sticks is because the fridge door  is made of some material including iron and iron   is a ferromagnet and basically it will point  it's magnetic field in the same direction as   the applied magnetic field right so if there's a  North Pole here on the magnet then the paramagnet   Will Follow That magnetic field it will have a  South Pole close to it and hence it will attract   and so this is why fridge magnets stick to the  door of your fridge right now diamagnets are the   opposite so the magnetic fields that's induced  are in the opposite direction right so the North   Pole induces another North Pole near it and so it  repels and so this is why diamagnetic materials   can repel now there's this famous experiment by  Andre Geim Ignobel Prize winner and Nobel Prize   winner you've got the Ignobel prize for levitating  a frog in a strong magnetic field and you can do   this because basically frogs are full of water  and so if you have a strong enough magnet you   can levitate a frog but there's other materials  like this which have quite a strong diamagnetic   season for example this pyrolytic graphite is a  material with particularly strong diamagnetism   and so if you put such a material on the magnet  it floats right this is not a superconductor this   is just a regular diamagnetic material yes it's  a relatively strong material it's a strong kind   of diamagnet however it's it absolutely floats  right superconductor of course also floats it   has a much stronger effect than this but the  fact that it floats is not a hundred percent   signal that it's a superconductor and so this  is why people have been saying that perhaps this   material is just simply just a regular diamagnet  another thing that people have been going on   about is theoretical verifications of basically  superconductivity in these materials one of the   first papers that came out came from the Sinead  Griffin from Lawrence Berkeley National Laboratory   and basically in this particular work what they  showed is that there's a kind of a flat band in   these types of materials now possibly because she  tweeted this along with a mic drop GIF of Barack   Obama people thought that this is absolute  smoking gun evidence that this really shows   that LK 99 is a room temperature superconductor  right and there's lots of tweets about how from   this result quote insanely bullish for Humanity  but in fact these types of results really only   show partial information about how it might be  plausible that superconductivity might exist in   these materials and the main result it really is  these calculator stations where they where they   calculate the band structure and basically what  is found in this paper are like two bands which   are very close to the Fermi levels separated from  the other bands by 130 meV and so why flat bands   are important is because basically if you've got  very energetic electrons which basically means   that the bands are not flat then it's harder to  combine them into this Cooper pair so that this   kind of condensation effect can happen right in  the flat band case if the electrons don't have so   much energy just a little bit of attractive force  can bind them together and then you can form this   pair and then you can form the superconductor and  so this is why flat bands are very interesting in   terms of superconductive materials because this is  one way that you can form these pairs so that you   can get your superconductor in the first place  but just showing flat and isn't really the end   of the story that it just makes it plausible  that you might get superconductivity but you   really can't take these as just like some kind of  smoking gun mic drop proof that LK 99 is going to   be a superconductor further calculations would  need to be done in order to basically prove this   okay so firstly what do you guys think so even  though why are everybody giving you that so much   attention then that's what I don't really because  even my first reaction when Valentin posted that   thing was like okay there goes another one of  those claims that's what I just said and that   was it I didn't really follow it so much I didn't  I wasn't really I don't know why yeah I think it   just because must be a combination of people just  be interesting it's a bold claim maybe a lot of   people want it to be true because it would be a  remarkable breakthrough absolutely yeah if it's   true people say that it's a Nobel Prize stuff like  that but it probably it really probably will be   right right it's that amazing it's that much of  a bold claim yes but the boldness is breathtaking besides that one paper has any other person said  something else yeah there's been I think there's   been about eight papers or so but just going  through them you can go on Wikipedia and then   there's like a running table of new papers  that are coming out on related topics and I   believe they're all actually seen this type of  paper this density functional paper and they   all have quite similar results actually so they  all find this flat bands and so I think I'm not   sure if there's much variety actually in the  theory there's a little bit more variety in   the experiments actually experiment wise nobody  has ever besides the Chinese who's tried and fell   yeah again there's I don't know maybe 10  experimental groups which are trying you   can again look on Wikipedia because it's just  it'll be just different tomorrow it'll be like   another five tomorrow so yeah but in terms of  the main ones as of today I think the ones with   actual results that you can actually have  a look at I think it's like the maybe three   Chinese groups there's an Indian group but the  other ones they say they have some results but   it's hard to find actual information yeah this  LK 99 has been around since right I thought maybe   the properties of this material should have  been well understood very well before now to   say whether this can happen or not I think on the  attention they adopted with copper or something so   I think they were working like a variation of  this material the properties should have been   well known such that even if they tweaked it  you should be able to immediately say yes or   no that's what I that's what I'm trying to get  at not necessarily but it looks like it's not   yeah I agree with you it's just a weird thing  about it because it's clear that they're aiming   for superconductivity right yeah because they've  been playing with this material for 20 years and   I think this has been their aim for the whole time  right yeah this is their pattern from three years   ago it's definitely it's in the title like you  can see that's what they're aiming for so so why   this very scratchy results and yeah why is it so  unclear like they had 20 years to look at this so   I don't understand that story at all yeah I don't  think only because like I said when I first saw it   when I first saw the post I was like here goes  another one of those fairy tales yeah but if I   sitting here and thinking if LK 99 has been around  for some time each property should have well known   such that even if you tweak it a little people  should we tell you okay this is what I should   expect it's like it's not like that I don't know  yeah and also I think it depends upon the sample   as well right like so I think different samples  for different properties and okay so it's I don't   know pretty unpredictable stuff maybe theories  to the risk here for this one actually huh yeah   I think theories in this field to the rescue you  can only do experience no no I agree with you the   experiments have the final say on this right but  at least the theory should be able to lead the way   to make some interpretation about what is going on  otherwise everybody will be still scratching their   head because it all boils down to whether are  they going to replicate what these people did or   I mean for experiments either to replicate what  these people did or to come out body and say okay   this material can never be this or can never  have this effect we can always wait for like   very advanced molecular simulations but but like  experimentally they find to not agreement with   you okay so I think I would say that so the the  problem with doing this kind of thing is these   are strongly correlated materials right and  this cuprate superconductivity which I think   people had a lot of trouble in creating models  and understanding that you have to solve these   very large spin models which are notoriously  difficult to solve right and it's not just   like a band structure problem band structure  is the first step then now you've got this   strongly correlated materials that you need to  solve which is like numerically like very hard   and then they have to prove it so I think it's  it's just you see it in experimentally you don't   I think yeah oh okay in theory can provide a few  sort of indications but you know it might be hard   so debunking this might take some time then but  this stuff is really easy to make so as long as   experimentally okay people already made it  right in a few days okay now they're just   going to kind of make it better or cleaner or  and basically everybody in the world makes it   even people in the garages and nobody finds  it and that's it that's the end of the story   so from this equal mechanics perspective they  claim that in this particular material the   electrons are able to pair at room temperature  and naturally yes okay yes that's a good claim   yeah I think I didn't go into so much the  mechanism but in the second paper they claim   some mechanisms of why this might happen and  basically what they say is that there's some   kind of by replacing the lead atoms with the  copper atoms there's some like kind of natural   pressure that builds up in the material which  makes instead of applying external pressure   you have some internal pressure which kind of  results in the same kind of effect but having said   that I've also seen again I think the best armor  Twitter thread saying that a lot of this basically   explanation is absolute nonsense it nobody can  really understand basically this mechanism as   they explain it yeah they are getting a lot  of scientists it is positive or negative both   yeah like it is like flow or that is not supported  by this so well it's a good way to get citations I think that even though I've presented  this pretty skeptically ultimately there's   still a chance that people can still find  superconductors in in some weird material   and it doesn't matter where you're from  it doesn't matter you don't have to be   from a great big university I mean there's no  reason why it doesn't exist and this is why   I think people are you know looking at this  uh seriously but with a nice skepticism this   is just how science works if you enjoyed  that and we'll see you for the next one

Channel: NYU Quantum Technology Lab

Views: 44,330

Keywords: room temperature superconductor, lk99 superconductor, lk99, superconductor, superconductivity, qcentre, korea, ambient, room temperature, cc:on

Id: w4SGvJLRWfU

Length: 26min 52sec (1612 seconds)

Published: Sat Aug 05 2023