611–620 of 906 posts
If this is comparable to the development of the transistor, what are the analogous vacuum tubes that I am living with today?
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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 But you're about 13 years out of date when you write that 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 be…
Yes the M855A1 was developed and started operational testing in 2010. However, it wasn't available to anyone who wasn't forward deployed until...my memory says 2015. The M855 is still used on post because a) it's cheap, and ballistically similar to the M855A1 and b) the production lines at Lake City are still geared for them
The Marine corps didn't formally adopt the M855A1 until 2017/2018. Brass didn't like it because it broke the feed ramps on machine guns. There was a big procurement SNAFU about this.
Marine corps times article on the matter:
https://www.marinecorpstimes.com/news/your-marine-corps/2017...
I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart about something you know nothing about. Something to consider. Frantic googling does not an expert make.
You're right about the copper core on the new model A1 - I thought it was steel entirely with thin jacket. I would argue that when, by weight, the majority of the bullet is steel, my original point still holds.
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Those mid 80s high temperature superconductors are now mass produced for NMRs and fusion startups. I don't think it's given that all superconductor breakthroughs will require 40 years to get to that point and there's good reason to believe they won't (startup penalty, industry bootstrapping, market finding, etc. have all been completed).
Those mid 80s high temperature superconductors are now mass produced for NMRs and fusion startups. As alluded to those same pop science magazines promised a fusion future too. Here we are, magazines extinct, with fusion startups using LN2 superconductors. Also: no quantum computers, no space colonies, no flying cars (or even supersonic planes), and twitter/reddit/facebook are worse than Usenet.
Also, no fusion startup I know of is using LN2 for superconductors. Liquid helium offers too much performance and quench margin with YCBO.
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Oof, all right then. Perhaps there's room for improvement, but there would need to be a lot before this is useful/competitive even in lab settings. For comparison, high temperature superconductors (in this context high temperature means tens of degrees kelvin) like the recently rather revolutionary ReBCO has critical current values measured in hundreds of thousands of amps per square centimeter. That would be a facto…
It's a thin film according to the article linked, but there is no mention of how thin it is (it could be a monolayer) and there is no mention of how wide the film was so the 250 mA figure can not be used to determine whether or not there is 'room for improvement' or even a necessity for that (unless it was already normalized, for which I see no evidence). The 'Critical current' isn't mentioned at all in terms of the…
>In 2008, Gozar et al. reported hightemperature interface superconductivity between metallic and insulating copper oxides(39). The thinner the layer, the greater the stress-inducing effect, the greater the strain, which seems to be the higher the superconducting transition temperature. Therefore, we argue that the stress caused by temperature and pressure brings a minute structural distortion and strain, which create an electronic state for superconductivity.
So the paper seems to confirm this, though the authors seem to be hopeful for general applications.
What we have here seems to be a clever trick to have ambient pressure superconductors by introducing crystal structure/microstructure stresses.
>But surely that will happen soon if this is real.
What I'm saying it that this is not so sure, may not be possible for a bulk material, may be insanely too expensive to be useful otherwise, and may be limited to very niche applications where milliamp superconductors might be useful (think sensors, microchips, and the like)
Sure is cool, but at the same time... cool your jets, eh?
A sister paper [0] has a photo of the material exhibiting the Meisner effect and levitating over a magnet, and claims to have a video too. Either they blatantly photoshopped the photo or they actually made a room temperature super conductor. I can’t see how the could have made a subtle mistake that resulted in magnetic levitation at room temp without making a superconductor. [0] - https://arxiv.org/abs/2307.12037
That said, from the video it mentions the superconductor was applied as a film over copper. But wouldn't plain copper also exhibit this effect due to eddy currents? I fail to see how the (supposedly) thin film is affecting the plate in this experiment. I'm probably missing something and I hope someone can enlighten me.
Exciting paper. I hope this won't be the same scenario as the other team that claimed a room-temperature superconductor in 2020 and was later proven to be a fraud. https://www.nature.com/articles/d41586-023-02401-2
The claims in this case are very simple to understand and very consistent with superconductivity, demonstrated on a macro scale at normal pressures and temperatures, there's video of the phenomena that doesn't make sense absent superconductivity, and most importantly: the method to produce the material is very simple, it is not going to be difficult at all for labs around the world to replicate this, and as other commenters have pointed out a lot of YouTubers are going to be able to replicate this.
So basically, this result could be fake, but it would need to be entirely faked results, faked video footage/photos, and it would be discovered very, very quickly because this is so easy to replicate. If it's true, people will have replicated this within a couple of weeks, which would be mostly sourcing materials. It will take longer than that for replications to publish (probably shorter for YouTubers), but this isn't going to be a situation where two years later we find out it's a fraud - we will know within a maximum of a couple of months that YouTubers can or can't replicate these results, and within a year whether a lab can or can't.
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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 be…
This post is a master class in why you shouldn't get all your information from Wikipedia. Press releases are not reality. Yes the M855A1 was developed and started operational testing in 2010. However, it wasn't available to anyone who wasn't forward deployed until...my memory says 2015. The M855 is still used on post because a) it's cheap, and ballistically similar to the M855A1 and b) the production lines at Lake Ci…
>I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart
Right back at you. I don't think I'm motivated by trying to sound smart, but rather by curiosity about the subject. Well, OK, half by wanting to sound smart (and win arguments) and half by curiosity.
In particular, I'm still curious about whether ammunition containing lead is still routinely used by the US military--if you still want to talk about it. I realize Wikipedia can be totally wrong. So far I haven't succeed in wringing information out of Google Search that would corroborate or support your assertion. When's the last time you (or someone you know to usually tell the truth) has observed M855 being used by the US military in significant quantities?
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I was with you on the first part. If this proves room-temperature/ambient-pressure is possible at all, that is huge. Not so sure about the "won't be long until it's optimized," though. There are a lot of examples where something seems perpetually 20 years away. I'd advise tempering the transistor-based optimism with just a skosh of fusion energy skepticism.
To be specific look at how long it has taken cuprate superconductors to find practical applications https://en.wikipedia.org/wiki/Cuprate_superconductor This was something that people said would change the world when I was in high school and it really hasn't. (For that matter, the fundamental physics is still not very well understood)
Which business do I invest in assuming this is real and has IP protection? It would be like buying Intel in 1971 or getting shares in Edison in 1878.
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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…