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Superconductor news: What’s claimed, and how strong the evidence seems to be

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Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#331

Post by denimnerd42 »

hinkley wrote: post #327
bradyd wrote: post #320

Earlier quoted context omitted.

They even make spokes that are rope https://berdspokes.com/pages/technology

I wonder if those have less or more breakin issues compared to spokes. With a spoke you have to reset the angle of the bend to the shortest distance between the hub and the rim. But with cables they have to settle in along their entire length. Doesn’t change the answer. They’re still compressing. They’re just pretensioned.

you sound highly confused, what is compressing? the rim? the spoke?

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#332

Post by hinkley »

denimnerd42 wrote: post #330
hinkley wrote: post #326

Earlier quoted context omitted.

That book I linked has another name, “the wheel building bible”. Jobst Brandt earned an obituary in Bicycling magazine including quotes from his friend Tom Ritchey (one of the original mountain bike makers). Jobst was a bike fanatic and a mechanical engineer. Bike spokes are not loose, they’re under substantial tension. Bolts, I just learned a couple weeks ago, work in the opposite way. A tightened bolt compresses th…

i own the book.. and also The Art of Wheelbuilding - Gerd Schraner of course in a properly built wheel usually all the spoke are under tension... i was just demonstrating the fact that the spokes on the upper half of the wheel are supporting the hub and are under greater tension than the bottom ones, the spokes on the bottom half of the wheel should remain in tension, but only through the fact that they are already u…

I think one of us needs to reread that book, because he emphatically denies that tension at the top of the wheel increases. It’s tension at the bottom that decreases.

> of course in a properly built wheel usually all the spoke are under tension...

No, a properly built wheel all of the spokes are always under enough tension you can bounce a penny off them. Always.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#333

Post by Helmut10001 »

doctorwho42 wrote: post #316
burtonator wrote: post #286

Earlier quoted context omitted.

I want ONE breakthrough like this in my lifetime. Something completely game changing.

Live to see SPARC turn on, there are some pretty smart people with models actually showing it breaking Q>3. Turns out the hardest part about productive fusion is the sustained high compression, and HTC tape really helps increase the compression by a large amount. (See their 20 Tesla test at the start of the pandemic)

Just want to mention for others: The first result for SPARC on google is SPARC (Scalable Processor Architecture), whereas SPARC (tokamak) [1] is what relates to Q>3.

[1]: https://en.wikipedia.org/wiki/SPARC_(tokamak)

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#334

Post by hinkley »

denimnerd42 wrote: post #331
hinkley wrote: post #327

Earlier quoted context omitted.

I wonder if those have less or more breakin issues compared to spokes. With a spoke you have to reset the angle of the bend to the shortest distance between the hub and the rim. But with cables they have to settle in along their entire length. Doesn’t change the answer. They’re still compressing. They’re just pretensioned.

you sound highly confused, what is compressing? the rim? the spoke?

You need to reread Brandt.

There are two situations when you can push on a string. One is when it’s frozen, and the other when it’s tensioned. How do you unload a bow string? You push it off the notches.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#335

Post by singularity2001 »

jeepers6 wrote: post #165
RyanAdamas wrote: post #150

Earlier quoted context omitted.

Wow, that's pretty damning. Good one.

“Damning” is the wrong word here. “Damning” would be “oh, look, the researchers forgot that the plot showing zero voltage also shows current dropping to zero. They’re clearly measuring a bad contact.” But the papers don’t show that. There’s no obvious contradiction unless you make some big assumptions.

OP works in the field and provides good arguments. You can translate the full blog post.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#336

Post by singularity2001 »

amluto wrote: post #203
groestl wrote: post #91

Earlier quoted context omitted.

> Has there been any commentary on that? German, but nevertheless: http://blog.fefe.de/?ts=9a3f8740 "I work in the field [...] we don't believe a word of this. [...] The data set in Fig. 4(b) is also a treat. It is VERY unusual when the heat capacity decreases again at high temperatures. This can happen at low temperatures, but not at high temperatures. [...] My personal assumption is that the authors measured an ins…

A 4-point measurement of an insulator would show zero current, as far as I know. A more plausible idea IMO is that it could be a 4-point measurement of a highly inhomogeneous sample. If the current probes make contact with conductive parts of the sample, and there is a conductive path between them, but one or both voltage probes are not contacting the conductive path, then the voltage measurement would be garbage and…

    A 4-point measurement of an insulator would show zero current, as far as I know.
The blog post suggests it might be electrical breakdown of the material at a certain voltage

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#337

Post by drexlspivey »

tigershark wrote: post #166
tux3 wrote: post #137

New scientist got a reply from the authors and a few other experts: https://www.newscientist.com/article/2384782-room-temperatur... >Kim has only co-authored one of the arXiv papers, while the other is authored by his colleagues at the Quantum Energy Research Centre in South Korea, some of whom also applied for a patent on LK-99 in August 2022. >Both papers present similar measurements, however Kim says that the seco…

“Both papers present similar measurements” I’m not a physicist expert of superconductors, although I’ve followed quite closely that field since the ‘90s. But if the measurements are similar and correct and if the video of lk-99 levitating above a magnet demonstrating the Meissner effect is not fake, I don’t really have an alternative explanation to account for all of that. I guess that we’ll see what happens in the n…

This guy is live tweeting his attempt to reproduce https://twitter.com/andrewmccalip/status/1684433849781202944

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#338

Post by Helmut10001 »

For those like me that know nothing of superconductivity, I found this [1] entry quite helpful to assess the impact, particularly:

> At atmospheric pressure the temperature record is still held by cuprates, which have demonstrated superconductivity at temperatures as high as 138 K (−135 °C).

[1]: https://en.wikipedia.org/wiki/Room-temperature_superconducto...

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#339

Post by IshKebab »

babypuncher wrote: post #242
IshKebab wrote: post #151

Earlier quoted context omitted.

"Active area of research" is quite different to "we don't know how they work". We know how they work. We might not have fully characterised the stability conditions , but that's not the same thing.

I think their point still stands, even if "we don't know how bikes work" is a flowery exaggeration.

But then we don't know how anything works...

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#340

Post by throwaw1yyy »

hackernewds wrote: post #222
carabiner wrote: post #92

Researcher on reddit thinks it's probably spurious measurement artifacts, not superconductivity: > I would say they are not faking it, but instead they just don’t understand what they are looking at. Based on what measurements they are doing, as well as how they are doing them, they do not have a good understanding of the standard processes to characterise a superconductor. Also, based on their analysis/discussion, t…

The redditors response seem to be generic, where is the counter evidence, and proof of their authority?

[flagged]
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