501–510 of 821 posts
This is exciting, but I try to maintain my composure. Good luck to all involved. I didn’t know science could be such a thrilling spectator sport.
One wit on a different social media site opined that "all technological advances such as plumbing and petrol result in lead poisoning, so perhaps this is real".
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Is there a name for this kind of effect?
I always call this a "local maximum" problem. Once you've optimized the crap out of your tech, any change makes it worse (e.g., replacing crossbows with primitive guns). But if you do switch, then optimizing that technology takes you to an even higher maximum. The problem is that you have to go backwards to go forwards, and you can't always predict (or convince the powers-that-be) that the end result will be better.
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I’m not an expert on this, but I think superconducting wires have an current limit, as a current flowing creates a magnetic field which the superconductor has to repel. I read that the paper states a very low current limit for LK-99, meaning it loses superconductivity once a very modest amount of current is passed through it.
That is.....kind of a huge limitation of the technology lol. Still very cool but less hype
Usually this is an optimization frontier, where something that has tetchy critical current/field at high temperature is going to have very good critical current/field at the same temperature as a lower-Tc superconductor.
If it superconducts at all at room temp, cooling it down even to 200K (about dry ice temp - quite cheap to do) could get you something very usable.
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I'm not expert, but I think about it like this: Resistance is the tendency of a material to convert electrical energy into heat. Higher resistance means more of the electrical energy is converted to heat per "time". A superconductor then has the cool property of being able to carry electrical energy without converting any of it into heat. That's obviously cool for energy transmission, but it also enabled some other c…
>Higher resistance means more of the electrical energy is converted to heat per "time". This isn't really accurate because increasing the resistance of a resistor in a given circuit will actually decrease the amount of heat dissipated. W = I V where I = V/R plug that in we get W = (V/R) V = V^2/R So Watts = Volts^2/Resistance. Increase resistance, decrease watts. Its better to just say that resistance converts voltag…
I presented it as an intuitive "feel" based idea of what a resistor does. It's very much not a numerically useful or physically accurate one.
Someone posted this in a comment on another post of LK-99: Wouldn't the first step be verification before replication ? I.e. have the original authors send out some LK-99 samples to other researchers to at least confirm "Yes, this thing is a high temperature superconductor". Wouldn't matter even that much if it were made with unicorn dust: it would be proof that high temperature superconductors are even possible, whi…
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Most people I talk to don't recognize the importance of room temperature superconductivity. A floating grain is cool, but not something that jumps out at people like a rocket or a big fusion reactor. The application is similarly unintuitive. Many here on HN ask why such a thing would be important, and they are probably the 99th (or 99.9th?) percentile in materials science and EE literacy.
>Most people I talk to don't recognize the importance of room temperature superconductivity. I don't. I read someone saying it would be the biggest breakthrough since fire. Is that true or hyperbole?
Its more like the transistor.
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So what's happening is they are demonstrating diamagnetism. Basically when exposed to an external magnetic field, that field induces a response in the material that repels it. When people think of magnetism, they think of polar charges that either attract or repel other polar charges. Diamagnetism is neat in that regardless of the orientation and polarity of the external field, a diamagnetic material is always repell…
So why is everyone getting so excited about superconductors when all we actually know is this (probably) exhibits diamagnetism? Is diamagnetism super rare outside of superconductors?
In comparison, levitating things like pyrolytic graphite seems to require truly massive magnets to achieve even millimeters of levitation: https://www.youtube.com/watch?v=VC3r9-OaWes
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> if you could grow a good single crystal of LK-99, it seems as if the superconductivity might only occur along one crystal axis: put crudely, you'd see superconductivity if you hooked your wires to two particular opposite faces of said crystal, but not to the others! Crystalline grain boundaries are already known to be a big deal in the efficiency of existing superconducting materials, and this would mean that polyc…
But what you just described would still be insanely valuable. Just in the field of semiconductors and chip fab, it would probably unlock insane gains.
But I dont want to jump to conclusions. I dont think its a drop in replacement for, say, the copper substrate.
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> Can I have my flying car now? Let's not forget the flying skateboard of the film "Back to the future". I loved it in the film and it's a dream that I still have today - I'm now almost 50 years old so I would probably crash and get killed by using it, but I would still give it a try :)
Unfortunately, while you can indeed build hoverboards with superconductors and they do work, you still need a magnetic surface for it to ride over. I don't believe generalized hoverboards that will work on all surfaces like BttF are possible.