6 ms·
Seems to be the same one that had a video a couple of days ago https://news.ycombinator.com/item?id=36953396 https://news.ycombinator.com/item?id=36953396 Back
by ufo 3y ago
Seems to be the same one that had a video a couple of days ago https://news.ycombinator.com/item?id=36953396 https://news.ycombinator.com/item?id=36953396
Back then, many asked if this was superconduction or merely diamagnetism. Does the new paper shine any light on this question?
- saladdressing 3y ago[dead]
- lamontcg 3y agoThe exact same video URL (https://www.bilibili.com/video/BV14p4y1V7kS/ https://www.bilibili.com/video/BV14p4y1V7kS/) is linked to in this article. There doesn't seem to be anything new here.
- deleted 3y ago[deleted]
- scarmig 3y agoThe paper shows a clear phase transition to diamagnetism as the material is cooled. That would be seen in superconductors and not in regular diamagnetic materials. I'm not aware of any that have that kind of phase transition. Though since we're in weird territory here, it's important to note some weird non-superconductor behavior that's beyond regular diamagnetism might be going on as an alternative explanation. But it is weird. ETA: also, in the presence of a magnetic field, that transition temperature decreases. That's pretty huge. Unless this paper is fraudulent, I take this as the biggest positive evidence so far that something besides simple diamagnetism is going on. And, cards on table, with the assumption that the paper is not fraudulent, this pushes my odds above 50% for the first time.
- bilsbie 3y agoWhat temperature?
- scarmig 3y ago326K (+127 deg F) and 340K (+152 deg F) for their less and more pure samples respectively. And, yes, if it's a superconductor as we understand them, that's the temperature at which it would have zero resistance as well.
- yreg 3y ago53°C and 67°C. Wow.
- seanthemon 3y agoSoon to be average temperatures, what luck!
- hksoftware 3y agoNonsense.
- yreg 3y agoIt's obviously a hyperbole. But if we once were to use these SCs to transport energy from solar farms in Sahara, it might have to operate in that temperature range.
- jacquesm 3y agoFive meters down in the desert you're under 25 degrees year round. It's the average that matters for soil temps, not the peaks. You can approximate this by taking the average air temperature and defining the surface as the top five meters. Below the 10 meter mark the day/night cycle influence is pretty much negligible (but that would be more costly). For instance: https://www.researchgate.net/figure/Temperature-variation-of-underground-soil-with-depth-for-typical-days-in-Malaysia-15_fig3_256838899 https://www.researchgate.net/figure/Temperature-variation-of...
- SamPatt 3y ago
- concordDance 3y ago> this pushes my odds above 50% for the first time. Time for you to make some money then? :D https://polymarket.com/event/is-the-room-temp-superconductor-real/is-the-room-temp-superconductor-real https://polymarket.com/event/is-the-room-temp-superconductor...
- danbruc 3y agoCan one know how many people are in that market? When prediction markets where mentioned early during the LK-99 story, I looked a bit around out of interest, which platforms exist, which topics they cover, how many people participate in that markets. Where I could find the number of predictors, it seemed pretty underwhelming - one, ten, fifty, a hundred, I think the highest I ever saw was a bit over a thousand, but even then less than a hundred or so where using real money, the majority was using play money. Did I miss the place where everyone is? Is this to expected because the are so many topics you can bet on? Are the resulting prices still meaningful even with a small number of predictors only?
- epivosism 3y agoManifolds main market on LK99 has 4.6k predictors now. This is a pretty strict version, at 33% now by 2025 https://manifold.markets/QuantumObserver/will-the-lk99-room-temp-ambient-pre?r=U3RyYXlDbGltYg https://manifold.markets/QuantumObserver/will-the-lk99-room-...
- bobsmooth 3y agoWebsite says $1 083 678 has been bet so far. You can scroll down to see all the shares and their prices.
- EvgeniyZh 3y agoMagnetic transitions as a function of temperature are not unheard of, and it makes sense for them to depend on external field (they are magnetic after all). Lanthanum cobaltite for example has transition from diamagnet to paramagnet, likely due to change of spin state (see, e.g., [1]). I'm not saying that's what's happening, but transition (if it is there, hastily written papers tend to have subtle inaccuracies) doesn't rule out non-SC diamagnetism [1] https://www.sciencedirect.com/science/article/abs/pii/S0925838819315889 https://www.sciencedirect.com/science/article/abs/pii/S09258...
- fcanesin 3y agoYes, in two forms: First it shows a temperature graph vs moment, as they heat it it loses the diamagnetism around the temperature LK99 is said to be superconducting. Second only a superconductor will have net-zero field, which means "stable" levitation. In the video they approach the sample with the magnet and flip it while the piece is mostly "in place". A regular diamagnet generates a external field that "follows" the field applied so it would likely move sideways, that is why to "levitate in place" a diamagnet people normally use a Halbach array. EDIT: A Halback array is made alternating the poles N-S of the magnet, so that forces of repulsion created by the diamagnet cancel. This is why you will see people using multiple magnets when levitating pyrolytic graphite.
- jacquesm 3y agoHalbach. Named after Klaus Halbach.
- seewhydee 3y agoThey have quantitative magnetization-versus-temperature data taken using a PPMS (an automated physical property measurement system). It shows strong evidence of some kind of diamagnetic transition at ~ 320K. It seems very likely now that this material has some kind of interesting magnetic property, whether or not it's due to superconductivity.