Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

science.org

Post reply on HN
Print view View original

441–450 of 501 posts

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

#441

Post by peteradio »

foven wrote: post #433
stu255 wrote: post #421

Earlier quoted context omitted.

Exactly, they have made a very big claim and made it very easy to replicate / falsify. It takes a few days to produce this stuff. Their paper is weak on data / results. This is exactly what you would do if your team genuinely believed you had discovered something monumental. In poker terms they are "all in" and they want to get called. That's why it is so interesting. If they had posted lots of extreme results but it…

As I mentioned in my above post, they have really dodgy data. Ideally, with something like this, you would have collaborators to verify alongside you as joint co-authors. I think something people underestimate if how easy to replicate samples are - crystal growth is difficult, and impurities are important. It is unlikely anyone will produce exactly the same sample only something close based on the process they've giv…

I think the politicking of the situation could explain why there was minimal involvement of outside collaborators.

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

#442

Post by dotnet00 »

intrasight wrote: post #265
local_issues wrote: post #78

Earlier quoted context omitted.

Ding ding ding! We still don't know how bikes work, we have a pretty good but incomplete model for lift on airplanes, and no one has the faintest why Tylenol works. We should figure that out! But we can definitely keep using all the applications until then. (Except for Tylenol, we keep learning how bad that stuff is) EDIT: It won't let me post more, so here's the answers to responses. For sure! https://www.cbc.ca/new…

We don't know how photosynthesis works but we know a ton about GROWING things. And life as we know it depends on photosynthesis.

How photosynthesis works at a cell machinery level is high school level biology.

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

#443

Post by hinkley »

denimnerd42 wrote: post #346
hinkley wrote: post #334

Earlier quoted context omitted.

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.

bro. you're wrong. just build a bicycle wheel some time. it becomes very obvious how they work as you take it through the various stages of tensioning.

Why do you think someone would talk about Brandt’s work if they hadn’t used it?

I’ve built more than half a dozen bicycle wheels. My set, my spare that my brother road (into the ground - my first set and practically the only problematic ones, but he road over bumps without getting out of the saddle), a set my dad commissioned from me, and a pair that he had me build for a friend. All by age 17.

I then worked as a mechanic for two summers of college. I was never the fastest, but if we had a customer we could not afford to disappoint, I or the senior mechanic got the job because my repairs did not come back.

I saved three or four wheels that would have been scrap by unwinding the spokes halfway and building it back up again like a wheel build. Only added an extra ten or fifteen minutes but it works a charm. When a good customer comes in on Wednesday before an out of town bike ride you can’t afford to fuck it up. I think I only built a couple professionally, and usually singles. That’s a lot of labor and few will pay.

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

#444

Post by hinkley »

matsemann wrote: post #372
hinkley wrote: post #250

Earlier quoted context omitted.

As a bit of an aside, most people don't know how bicycle wheels work. There's a whole section in https://en.wikipedia.org/wiki/The_Bicycle_Wheel that talks about how they actually work. It's not tension at the top, it's compression on the bottom.

Not to appeal to authority, but I wrote my thesis on bicycle wheels. You got it the wrong way around.

And have you read Brandt’s work?

https://news.ycombinator.com/item?id=36891231

The world is full of papers that are wrong. Including maybe the one this whole thread is about. It’s okay, it happens. Science doesn’t find right or wrong, though a lot of people think so. It finds more wrong and less wrong.

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

#445

Post by hinkley »

denimnerd42 wrote: post #347
hinkley wrote: post #332

Earlier quoted context omitted.

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.

no. you're assuming the rim has no deflection which is untrue. if you build a rim out of schedule 80 steel pipe then yea. but 300-400-500g rims on high performance bikes do not act like that. the spokes are constantly loading and unloading tension as they bash through rocks and over jumps. the point is that the pretension on the wheel needs to be high enough the spokes do not loosen too much under these forces. if th…

I’m not assuming the rim has no deflection. What makes you think that.

Anyway, this sums it up pretty well. Someone has a longer memory than I:

https://news.ycombinator.com/item?id=36891231

If you’re talking about twisted spokes unwinding, you don’t have to reach zero load for that to happen. You just need to reduce the load enough so the rotational force overcomes friction. Tension will also try to unwind a screw as well. But the thread pitch on spokes is very fine, which lessens that force. If you build spokes like wood screws we would have problems and that has nothing to do with reaching 0 newtons.

You can release a lot of those tensions by squeezing the spokes mid build. Just don’t wait until they’re too tight to do it. I had a pulse in my rear wheel that probably came from doing that wrong the first time. Unless it was a factory defect, I must have overtensioned and warped a brand new Mavic aero rim ever so slightly. Expensive lesson, but it could have been worse.

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

#446

Post by weberer »

macromaniac wrote: post #117
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…

He doesn't provide an actual counterargument,he just says he doesn't like the data without explaining why. His earlier comment that graphite can do the same thing is untrue afaict. Graphite can repel the magnetic field but it would slide off, this is why in diamagnetic experiments multiple magnets are used to keep it in place. In the video it doesnt seem to be sliding anywhere, so imo the video is not showing diamagn…

>He doesn't provide an actual counterargument,he just says he doesn't like the data without explaining why.

Welcome to Reddit

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

#447

Post by _4bjt »

macromaniac wrote: post #117
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…

He doesn't provide an actual counterargument,he just says he doesn't like the data without explaining why. His earlier comment that graphite can do the same thing is untrue afaict. Graphite can repel the magnetic field but it would slide off, this is why in diamagnetic experiments multiple magnets are used to keep it in place. In the video it doesnt seem to be sliding anywhere, so imo the video is not showing diamagn…

One of the authors explains in this article: https://www.newscientist.com/article/2384782-room-temperatur...

> However, only one edge of the flat, coin-like material fully levitates, while the other seems to stay in contact with the magnet. Kim says this is due to the sample being imperfect, which means that only some part of it becomes superconductive and exhibits the Meissner effect.

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

#448

Post by 7373737373 »

jeepers6 wrote: post #419
soligern wrote: post #48

Earlier quoted context omitted.

I’m sure this is on Applied Science’s (a YouTube channel) radar. He recently went on a deep dive on making YBCO superconductors so it’s right up his alley.

https://nitter.net/BenKrasnow/status/1684431462643437569#m

A livestream of this would be awesome

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

#449

Post by curiousObject »

lolc wrote: post #403
mrguyorama wrote: post #108

Earlier quoted context omitted.

There's also probably a hundred labs skipping over replication completely to try and beat someone else out on a random permutation of these materials and methods and hoping to get lucky.

I can't see why they'd skip replication given the uncertain status of the original process. They'd try to replicate as closely as possible, confirm they have a superconducting material, then they'd branch out from their established process. Starting from a variation means they don't know whether it doesn't work because of the variation or because it doesn't work at all.

That’s not unreasonable, but the high-risk, high-reward approach would be to let researchers elsewhere do basic verification, while you try to leap a step ahead of them by going directly to derivative variations.

Abandon the work if nobody can replicate LK-99 within a few weeks and you haven’t really lost out badly.

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

#450

Post by babypuncher »

IshKebab wrote: post #339
babypuncher wrote: post #242

Earlier quoted context omitted.

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...

But their point is we don't need a 100% complete scientific understanding of something in order to engineer it into something cool or useful.
Post reply on HN