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Successful room temperature ambient-pressure magnetic levitation of LK-99

arxiv.org

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Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#891

Post by Nifty3929 »

f6v wrote: post #490
wenyuanyu wrote: post #154

Earlier quoted context omitted.

I am from China. Not surprised at all.. Young researchers in China often face intense competition and pressure. While they are generally well-funded in the short-term, even more so than their counterparts in the US or Europe, the lack of long-term career security can be challenging. They must continuously chase after every potential scientific breakthrough, like LK-99, not just out of passion or curiosity, but as a n…

> lack of long-term career security can be challenging I don’t know, my fellow PhD students in EU have the same fears.

But it sounds like at least in China, there is some clear action they can do about it, so that’s the motivator.

What would some PhD student in EU who is worried about job security be able to do about it constructively?

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#892

Post by ep103 »

kevstev wrote: post #864
jacquesm wrote: post #785

Earlier quoted context omitted.

It's even more stark when you come to realize how big the pyramid is just under a new scientific breakthrough. But there are also examples of people that stayed the course against common wisdom (and sometimes while being derided) who eventually succeeded in what they were doing. This is to me the kind of science that is most deserving of prizes, to encourage others to keep looking even when the answers are far from o…

I feel that way about string theory. I am merely an airmchair physicist, though I did have a physics minor in college, but it just feels... wrong. Ever more layers of complexity to explain away holes, and no real predictive power. But at least as of ~10-15 (and maybe still today, I have lost touch with that world) years ago, saying this in any serious setting would not make you any friends, nor get you any funding. I…

I'm far outside of these social circles nowadays, but I stumbled across this youtube video of a phd candidate talking about string theory recently (https://www.youtube.com/watch?v=kya_LXa_y1E), and it seemed to imply that the pendulum in those social circles is swinging back again.

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#893

Post by VygmraMGVl »

stolsvik wrote: post #547
qnleigh wrote: post #263

Earlier quoted context omitted.

That's right. The standard way to measure resistance without being sensitive to contact resistance is called the four-terminal method, see ( https://en.m.wikipedia.org/wiki/Four-terminal_sensing ). You drive a current using two outer wires, but then detect the voltage across the sample using a different pair of wires. You'll measure zero voltage if it's superconducting, since V=IR. Or if one of the probe wires became…

Don’t you also measure the current of the “inner probes” (the ones “driving a current”), to verify that you do have contact?!

You drive current through the outer probes. The inner probes measure voltage and are not driven. When measuring non-zero resistance, you can vary the driving current to confirm the voltage you measure also varies linearly (ex thermal effects, capacitance of the material etc.). When measuring zero resistance, you can't distinguish vs a voltage probe error.

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#894

Post by squeaky-clean »

pyrale wrote: post #506
scarmig wrote: post #322

Earlier quoted context omitted.

They were. E.g. see here for a major, good paper announcing a novel class of superconductors: https://sci-hub.ru/https://link.springer.com/article/10.1007... The difference now is that we're seeing a premature preprint being replicated in real time. Even in that paper, the authors note: "The way the samples have been prepared seems to be of crucial importance: Michel et al. [21] obtained a single-phase perovskite by…

> a premature preprint Considering how that preprint has sparked interest in other research institutions and multiplied the resources allocated to the problem, I would say this publication was not premature, it's most other research results that are late.

The paper was leaked early. The team wanted more time to get more attempts at producing it and improving their yield. The paper also wasn't generally up to their writing standards. It's essentially an early draft that was leaked.

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#895

Post by im3w1l »

andbberger wrote: post #422
hwillis wrote: post #383

Earlier quoted context omitted.

You can't get CT scans very often, because they hit you with large doses of ionizing radiation. Ultrasounds are low-resolution spotlights; you shine them at a particular spot to diagnose something specific. With this you could get an MRI at your annual checkup. You could diagnose all number of diseases like that, not to mention 95% of cancers. Each year your scan is automatically compared to the previous year, and an…

we could do annual scans with current tech. the fundamental limitation of MRI is proton relaxation time, which limits the sampling rate. the path to reducing scan time and thus cost is to use a more sophisticated reconstruction method to reduce the number of required samples. this is being worked on. i don't have any data here, but I am dubious that a room temperature superconductor will bring down the price of MRI m…

It's my understanding that long-known high temperature superconductors already don't require helium cooling. How does that fact fit into the picture?

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#896

Post by Sharlin »

awb wrote: post #768
someplaceguy wrote: post #404

Earlier quoted context omitted.

Reading further below, I'm actually amazed by all the theoretical studies that have already been done from first principles (all apparently supporting the possibility of superconductivity). That's a pretty fast pace for science!

Magnus Carlson said that if you tell him there’s a winning move on a chess board he could find it very quickly, because his focus becomes extremely narrow. I wonder if something similar is happening here. Since the scope was defined as LK-99, it becomes a narrow query instead of a broad one.

This is not just telling someone there's a winning move. It's telling them that X is a winning move and they just have to verify that X is indeed one. Many, many problems are such that it's difficult to find a solution but easy to verify one.

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#897

Post by rc_kas »

anigbrowl wrote: post #781
softwaredoug wrote: post #705

I no nothing about superconductors. And have been largely ignoring this until it seemed more certain. Can someone ELI5 why this matters? What does it enable technologically? Flying cars? Fusion reactors? Magic fix for global warming?

Conventional conductors have resistance, so when you run electrical current through them they heat up; this is why laptops and desktops have fans to cool the chips, why phones get hot and so on. Superconductors transmit energy without resistance, so the heating problem goes away and the energy costs of running the device go way, way down. Basically you can pump more through smaller wires without worrying about them m…

thank you friend for this post

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#898

Post by hwillis »

fellowmartian wrote: post #679
hwillis wrote: post #383

Earlier quoted context omitted.

You can't get CT scans very often, because they hit you with large doses of ionizing radiation. Ultrasounds are low-resolution spotlights; you shine them at a particular spot to diagnose something specific. With this you could get an MRI at your annual checkup. You could diagnose all number of diseases like that, not to mention 95% of cancers. Each year your scan is automatically compared to the previous year, and an…

Full body MRI scans are only expensive in the West, outside the west you can get one done for $250. This is a labor and regulatory capture problem and not a technology problem and will not be affected in any meaningful way by better superconductors.

Even if it were $250, that's a pretty high cost relative to the annual cost of insurance. It's too high to justify as a routine diagnostic tool. The financial benefit here is that earlier identification would save money in the long term treatment. MRIs don't cure cancer, so the direct benefit only applies to the limited savings on a very small subset of people of the people who actually get cancers that could be identified earlier.

The real benefits are indirect (from the viewpoint of the insurance people who unfortunately pay for it)- quality of life is much better if you catch it earlier, and the medical research benefits are huge.

Realistically, it's also not $250 even outside the US- not for the resolution needed to diagnose cancers. That's below the depreciation cost of a high end (say $1M) machine. 12 scans a day (it takes roughly an hour for an average scan, 12 is per day per machine is pretty average[1]) 7 days a week for 10 years is 43,800 scans. So ignoring interest, labor, and absolutely everything else that's $228 per scan.

A full body MRI takes an hour only for small patients. More realistically 1.5-2 hours.

[1]: https://www.auntminnie.com/index.aspx?sec=ser&sub=def&pag=di...

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#899

Post by stuckinhell »

Tade0 wrote: post #716
softwaredoug wrote: post #705

I no nothing about superconductors. And have been largely ignoring this until it seemed more certain. Can someone ELI5 why this matters? What does it enable technologically? Flying cars? Fusion reactors? Magic fix for global warming?

Everything that involves powerful magnets and benefits from making things float - like bearings. Robots and exoskeletons come to mind. One of the more bonkers applications would be to wrap Mars around the equator with it, creating an artificial magnetosphere. Temperatures on Mars are pretty low, but during the Martian summer they get to a nice 20°C there, so currently available superconductors are not up to the task.

Whoa, where can I read more about something like that ?!

Re: Successful room temperature ambient-pressure magnetic levitation of LK-99

#900

Post by m3kw9 »

cypherpunks01 wrote: post #21

Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.

The korean guy say this is a 1d superconductor (as opposed to 2d sheet or 3d, which means you would need a single line of superconducting molecules from end to end. Its likely why it doesn't float all the way as only parts of it has these and scattered all over the chunk of solid.

However, if they perfect 1d production, they can layer in a bunch of them to create a quasi 2d or 3d superconductor.

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