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The first room-temperature ambient-pressure superconductor?

arxiv.org

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Re: The first room-temperature ambient-pressure superconductor?

#561

Post by mabbo »

thehappypm wrote: post #401
andreiklochko wrote: post #389

Guys, even if everything in this paper is true, the material as it is might have limited applications. From what they show, the critical field and critical current seem very low. 2500 Oe is like 0.25 Tesla. Even REBCO at 77K is >1T. And 2500 Oe is not even at critical temperature but much lower. From skimming through the article I couldn't find the sample size of the current measurement to get the critical current de…

They've just proven (if true of course) that it's possible at all. That is a massive, massive leap. And once it's possible, it won't be long until it's optimized. We've seen this everywhere -- transistors were once huge and now nanometers; solar cells have improved in every where; batteries are cheaper and better than ever.

Many years ago, as an undergrad, I was telling a grad student friend how I'd been learning about the Selection algorithm- it lets you pick the Kth largest element from an unsorted list in linear time, which is pretty neat.

I said "It's O(n), but the constant is ridiculous in most implementations so it's usually better just to sort and then pick the kth element". The grad student friend said something that stuck with me: "Sure, but the algorithm proves it's possible to find the kth element in linear time. That was never guaranteed. Now we just need to find a better way to do it."

Random conversation that stuck with me, and they probably forgot it a moment later.

Re: The first room-temperature ambient-pressure superconductor?

#562

Post by JumpCrisscross »

jacquesm wrote: post #532
JumpCrisscross wrote: post #513

Earlier quoted context omitted.

> it's the miniaturization that's the hard part We don't have a working fusion system to miniaturize. Stellar fusion happens at much lower temperatures than what we're trying to do on Earth.

The sun's core is actually very hot, it is the outer layers of the sun that are much cooler. We're trying to do this at roughly twice the temperature than the core of the sun, and I realize the difference is millions of degrees but on a relative scale this doesn't add much complexity, it would be almost as difficult if the plasma would be only half the temperature that they are shooting for. And in a way that higher…

> what we are doing is in fact to re-create conditions roughly on par with what is happening in the core of the sun

My understanding is we are not. (Not an expert!) The Sun's core runs around 15 MK [1]. A tokamak, 150 MK [2]. Orders of magnitude rarely come for free in physics.

We need those higher energies because we can't, like the Sun, swaddle with the mass of a hundred thousand worlds a low-temperature, low-frequency weak-force mediated proton-proton reaction [3]. The Sun relies on quantum tunneling to overcome the Coulomb barrier. We humans have to increase the reaction energy so it doesn't all bleed off before anything happens [4], which means using the strong force [5].

[1] https://solarsystem.nasa.gov/solar-system/sun/in-depth/

[2] https://euro-fusion.org/faq/what-is-the-temperature-generate...

[3] https://en.wikipedia.org/wiki/Proton–proton_chain

[4] https://en.wikipedia.org/wiki/Bremsstrahlung

[5] https://medium.com/@deepfuturetech/practical-proton-proton-f...

Re: The first room-temperature ambient-pressure superconductor?

#563

Post by hollerith »

hguant wrote: post #544
hollerith wrote: post #508

Earlier quoted context omitted.

Tangentially, the US Army has completely stopped using lead in bullets. Their 5.56 NATO ammo has copper where the lead used to be (i.e., inside a brass jacket) which reduces performance because copper is only 2/3 as dense as lead.

Sorry, but this is entirely incorrect. First, terms - brass is not used to "jacket" a bullet. Brass is used as the case material for the cartridge. Steel, and nickel plated steel are some times also used here. "Jacketing" (as in, Full Metal Jacket) refers to the material that wraps around the exterior of the projectile. As far as I'm aware, the material used here is almost always copper, or a copper alloy (cupronicke…

I'll concede that my assertion that the jacket is brass might be incorrect. But you're about 13 years out of date when you write that

>There are no bullets in the US inventory, to my knowledge, that use a copper core. Copper is simply far too expensive to be used at that scale . . .

Photos of cross sections of the M855 and M855A1:

https://twitter.com/izlomdefense/status/1202516482082639872/...

M855 has a lead plug behind a steel penetrator. M855A1 has a copper plug behind a steel penetrator. So, I stand by my "copper where the lead used to be". I never said there wasn't a steel penetrator.

From https://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO:

>For general issue, the U.S. Army adopted the M855A1 round in 2010 to replace the M855. The primary reason was pressure to use non-lead bullets. The lead slug is replaced by a copper alloy slug . . . The U.S. Marines adopted the Mk318 in early 2010 due to delays with the M855A1. This was a temporary measure until the M855A1 was available for them, which occurred in mid-2010"

As you probably know, most combat soldiers in the US Army and Marines carry a rifle (usually an M4 these days IIUC) that fires 5.56×45mm NATO, so it is probably the ammo type that the US military uses the most of.

Re: The first room-temperature ambient-pressure superconductor?

#564

Post by foota »

downvotetruth wrote: post #550
lopuhin wrote: post #428

Earlier quoted context omitted.

I think it's even from 2021-08-25, see https://patents.google.com/patent/KR20230030188A/en?oq=WO202...

2 years after the patent application and 4 months since publication and not involving any lab an author is not apart of to replicate a process that should take a week - a reason to wait for seems hard to justify.

Maybe it's some kind of game where they pre file things and then fill in the details but get a better date? I was concerned when I saw this as well though

Re: The first room-temperature ambient-pressure superconductor?

#565

Post by PBnFlash »

sheepscreek wrote: post #48

One of the authors in a related paper[1] is Hyun-Tak Kim. He has many publications in peer-reviewed journals[2]. One even has > 1500 citations[3]. I can't tell if there is a catch anywhere, this seems pretty legitimate. Also, unlike some previous claims that required sophisticated setup to reproduce, this seems dead simple. I think we will hear from other researchers very soon. 1. Superconductor Pb10-xCux(PO4)6O show…

Okay I can believe super conductivity, but having LK-99 a registered trademark already is where I draw the line.

Re: The first room-temperature ambient-pressure superconductor?

#566

Post by mirekrusin »

andreiklochko wrote: post #389

Guys, even if everything in this paper is true, the material as it is might have limited applications. From what they show, the critical field and critical current seem very low. 2500 Oe is like 0.25 Tesla. Even REBCO at 77K is >1T. And 2500 Oe is not even at critical temperature but much lower. From skimming through the article I couldn't find the sample size of the current measurement to get the critical current de…

Can you make efficient chips with it?

Re: The first room-temperature ambient-pressure superconductor?

#567

Post by dTal »

gerdesj wrote: post #534
jacquesm wrote: post #518

Earlier quoted context omitted.

Very true. I remember cheering since the mid 80's every time the temperature for superconductivity went up, sometimes with 20 degrees K in one go. And then it was quiet for a long long time with a plateau. More recently, two major jumps, the last one of > 50 degrees (2017, H2S), and now this... https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002...

I've forgotten how many times one of the most important thresholds in our times has been bumped up a bit. Now we seem to be offered heaven on a plate. If superconductance can be reliably demonstrated at RTP (you wear a light cotton shirt, instead of 1cm thick fancy weaves involving an awful lot of rubber) then we are laughing all the way to ameliorating climate change. Even if this result is confirmed then I think it…

If the argument is that superconductivity = better efficiency = less energy use, then I am afraid that Jevon's Paradox has some bad news:

https://en.wikipedia.org/wiki/Jevons_paradox

Re: The first room-temperature ambient-pressure superconductor?

#568

Post by allenrb »

allenrb wrote: post #4

If this were true, I would’ve expected to see it on the front page of the New York Times, not hiding in a scientific journal. Color me skeptical, with a hint of optimism.

Ok, looks like I forgot this is HN for a moment there. Must have been excited. Yes, I am familiar with how science works, including the publishing side.

What I was trying to say was more along the lines of, if this is legit, I’m surprised we weren’t first hearing about it in the mainstream media after a leak.

I’m absolutely not in favor of any more Pons & Fleischmann moments.

Re: The first room-temperature ambient-pressure superconductor?

#569

Post by dspillett »

Maxion wrote: post #129
dspillett wrote: post #35

Earlier quoted context omitted.

No, I agree with you that a quiet “this is what we've found, this is what we think it means, please reproduce or tell us if you find something we've misinterpreted”, rather than a public fanfare, is how a potential scientific breakthrough should be done IMO. I think I cross-pollinated this thread with another where someone was asking “if this is true why isn't it on the front pages”. The extraordinary evidence I'd wa…

But this is exactly the quiet please reproduce? It's a preprint posted to arxiv, with a very easy to follow material synthesis process in the supplemental materials section?

> But this is exactly

Yep. But that doesn't stop me being sceptical of such a jump in success (from tens of K below room to tens+ above at ambient pressure) which is where this sub-that started.

As already stated ("I think I cross-pollinated this thread with..." in the post you replied to) I confused things by mixing replies to different posts in the same place.

Re: The first room-temperature ambient-pressure superconductor?

#570

Post by jacquesm »

JumpCrisscross wrote: post #562
jacquesm wrote: post #532

Earlier quoted context omitted.

The sun's core is actually very hot, it is the outer layers of the sun that are much cooler. We're trying to do this at roughly twice the temperature than the core of the sun, and I realize the difference is millions of degrees but on a relative scale this doesn't add much complexity, it would be almost as difficult if the plasma would be only half the temperature that they are shooting for. And in a way that higher…

> what we are doing is in fact to re-create conditions roughly on par with what is happening in the core of the sun My understanding is we are not. (Not an expert!) The Sun's core runs around 15 MK [1]. A tokamak, 150 MK [2]. Orders of magnitude rarely come for free in physics. We need those higher energies because we can't, like the Sun, swaddle with the mass of a hundred thousand worlds a low-temperature, low-frequ…

If you start to think of 'temperature' of individual particles as 'speed with which they move' that is a useful rough approximation of trying to figure out what it means that something has a particular temperature. Containing the plasma is hard not just because of the temperature it is at but simply because it tends to destroy anything that contains it and that doesn't really change all that much for 15 million degrees Celsius, 30, 100 or 150. What it does change is that at 150 million degrees Celsius you have some hope of extracting useful work from a very small quantity of plasma. If you don't get it up to those temperatures - again, as far as I understand it - then you will always be putting in more energy than you are gaining because of some fundamental physics limitations.

So the smaller you make your reactor the hotter you'll have to make it to make it net positive. This leads to the counter intuitive result that making a much larger reactor is actually quite possibly easier than making a really small one. The rate of heat loss is much smaller for a larger reactor and so it becomes easier to sustain the reaction and to extract useful energy from it.

It is very well possible that none of the reactors currently on the drawing board and under construction are going to be working well enough to give us a sustained reaction resulting in net yield. But we're getting closer and closer to that and there is some (small) chance that I will still see this in my lifetime.

The catch is that as long as you can't get a small reactor to work getting funding for a much larger one (which you actually may be able to get to work) is going to be extremely difficult. We like to see proof before we scale up. In this case it may well be that such small scale proof can't be done or can't be done in a way that it it will convince backers that a larger scale device will work.

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