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Room temperature, ambient pressure superconductivity – this time for real?

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Re: Room temperature, ambient pressure superconductivity – this time for real?

#261

Post by it_citizen »

eesmith wrote: post #236
svachalek wrote: post #225

Earlier quoted context omitted.

Magnets can also levitate over other magnets, so it's not only possible with superconductors. But it does happen with superconductors. The magnet will induce a current in the superconductor, which creates a magnetic field, which repels the magnet.

> Magnets can also levitate over other magnets Earnshaw's theorem describes why a free-floating (paramagnetic) magnet cannot levitate over another such magnet. There must be at least one stable axis which is not from a magnet. See https://en.wikipedia.org/wiki/Earnshaw%27s_theorem > The magnet will induce a current in the superconductor That's a different sort of levitation. See https://en.wikipedia.org/wiki/Electrod…

So does that mean the video would exclude honest mistakes from the researchers? Either it is indeed a superconductor at room temperature or the makers of video actively faked the result.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#263

Post by AdamH12113 »

jacquesm wrote: post #256
AdamH12113 wrote: post #211

Earlier quoted context omitted.

Unfortunately, this is not even close to correct. Resistive losses in wires are not the only cause of wasted energy, and in most battery-powered devices they aren't very important at all. How is a superconductor supposed to help with e.g. switching losses in a buck converter, or reduce the amount of energy stored in a transistor's gate capacitance?

> How is a superconductor supposed to help with e.g. switching losses in a buck converter That one I can answer for you: because it would reduce the time to go from 'on' to 'off' due to the much more rapid flow on account of reduced resistance. The currents in a buck converter can be very high because they are short, but that is also exactly where you'll find the losses: in the transition from 'off' to 'on' and vice…

Sure, the inductor conduction losses would go away (and that's a substantial improvement!), but I'm not sure what you're talking about with regard to reducing switching time. I don't think the MOSFET gate drive is limited by the wire that connects to it.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#264

Post by johncalvinyoung »

moffkalast wrote: post #126
willis936 wrote: post #9

Earlier quoted context omitted.

It is fun to joke about alien technology. But they are unrelated in reality. In fact they are pretty uncorrelated in terms of timeline. This material has supposedly been waiting in the wings for a while.

> has supposedly been waiting in the wings for a while I'm not sure if that holds, the tic tac UFO has no actual wings :P

idiom stems from waiting in the wings of the stage... i.e. just out of sight of the audience.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#265

Post by smallnamespace »

jncfhnb wrote: post #237
foven wrote: post #215

Earlier quoted context omitted.

Glad to see a realistic take on HN. Endlessly frustrating to see people be like "this will be replicated in days". Yeah, sure, let every other lab just drop what they're doing, order all the reagents on express, do a thorough characterization making sure they understand the impurities and crystal phase, then perform good airtight measurements in a couple days. Crystal growth always has complications many times outsid…

Feels like you’re strawmanning the idea here. It’s not “every lab” it’s “at least one lab”. Jeez I sure hope at least one lab can spare the time to bother reproducing a room temperature semiconductor claim.

One lab is definitely not adequate.

Replication attempts don't give you an unambiguous signal, many things can go wrong.

If one lab hasn't succeeded in replicating the paper, does that mean the paper is wrong, or just that a necessary step wasn't documented clearly or followed correctly?

More labs trying to replicate give you more independent signals.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#266

Post by lamontcg »

ncann wrote: post #193
anonymouse008 wrote: post #3

Earlier quoted context omitted.

I'm following this fellow: https://twitter.com/andrewmccalip Seems to have the right energy [edit thanks folks] https://nitter.net/i/status/1684433849781202944 Here’s a more colorful play by play as well: https://nitter.net/8teapi/status/1684586672917565443

So the authors are disciples of a professor specialized in superconductor, their own Master and PhD were about superconductor, then they created a lab/company specifically for researching superconductor. This is contrary to my earlier belief that they were just normal chemists/physicists that happened to stumble upon an interesting material. Unless they're lying through their teeth, it's hard to believe they would no…

https://twitter.com/8teapi/status/1684571913908293633

Lee was stuck as an adjunct professor for 19 years. Kim thinks that physicists all have their head up their ass and he knows the shortcut to discovering superconductivity. And nature wouldn't publish their paper.

Combined with their inability to accurately measure Tc and a lot of skepticism already out there that their graphs show what they say they do this looks like poor science.

Which is not to accuse them of lying. It looks like they're just not very good, but think they're geniuses.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#267

Post by jacquesm »

AdamH12113 wrote: post #263
jacquesm wrote: post #256

Earlier quoted context omitted.

> How is a superconductor supposed to help with e.g. switching losses in a buck converter That one I can answer for you: because it would reduce the time to go from 'on' to 'off' due to the much more rapid flow on account of reduced resistance. The currents in a buck converter can be very high because they are short, but that is also exactly where you'll find the losses: in the transition from 'off' to 'on' and vice…

Sure, the inductor conduction losses would go away (and that's a substantial improvement!), but I'm not sure what you're talking about with regard to reducing switching time. I don't think the MOSFET gate drive is limited by the wire that connects to it.

It isn't but the capacitor that is sitting on the far end of that circuit is limited by how fast you can pump current in or out. And if your current can go up considerably then the capacitor will charge that much faster and so your losses will be smaller because for the same 'on' duration of the MOSFET you can move more charge. Clearer now?

Re: Room temperature, ambient pressure superconductivity – this time for real?

#268

Post by eesmith »

it_citizen wrote: post #261
eesmith wrote: post #236

Earlier quoted context omitted.

> Magnets can also levitate over other magnets Earnshaw's theorem describes why a free-floating (paramagnetic) magnet cannot levitate over another such magnet. There must be at least one stable axis which is not from a magnet. See https://en.wikipedia.org/wiki/Earnshaw%27s_theorem > The magnet will induce a current in the superconductor That's a different sort of levitation. See https://en.wikipedia.org/wiki/Electrod…

So does that mean the video would exclude honest mistakes from the researchers? Either it is indeed a superconductor at room temperature or the makers of video actively faked the result.

I'll quote from the linked-to page:

> In both of these magnetic repulsion videos, keep in mind that magnetic repulsion and/or levitation are not, by themselves, probative of superconductivity: a diamagnetic material such as pyrolytic graphite [16], can be made to levitate [19] in a magnetic field without being superconductive.

See https://en.wikipedia.org/wiki/Magnetic_levitation#Diamagneti... .

Re: Room temperature, ambient pressure superconductivity – this time for real?

#269

Post by MobiusHorizons »

timerol wrote: post #204
MobiusHorizons wrote: post #200

Can someone help me understand what it means for a superconductor (which should have zero resistance) to have such a low current capacity? Does this mean it's possible to have a voltage drop across the superconductor? Does that voltage drop somehow not result in power dissipation? Is it something like capacitive or inductive reactance?

Superconductors aren't always superconducting. There is a set of circumstances in which superconduction happens. If the current is below this limit, voltage is 0. If current is above this limit, then voltage is more accurately predicted from bulk resistivity numbers. This image is on it's side from a normal I-V curve, but accurately describes the relationship: https://i.stack.imgur.com/5Irds.jpg . At Ic the material…

Thanks that explanation makes a lot of sense.

Re: Room temperature, ambient pressure superconductivity – this time for real?

#270

Post by tigershark »

febed wrote: post #28

A source (German) attributed to the Max Planck Institute for Solid State Research thinks the paper is bogus [0] [0] https://blog.fefe.de/?ts=9a3f8740

He didn’t even try to explain the levitating video displaying the Meissner effect..
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