General Science Thread

From what I heard, there's a rumor that the guy who released it prematurely did so because he was about to leave and was worried they'd Unperson him from the paper for it.

Oh yeah, I've seen folks being skeptical of their measurements — the heat capacity attributed to the material is apparently a bit sus (most solids have around 3R or 25 J/mol K at room temperature, notwithstanding the drastic increase exhibited by superconductors near their transition temperature), and it's not clear whether the V-I curves actually show zero resistance at the "superconducting" parts. And they seem to have written the paper in Word, to boot.

On the other hand, the preprint response linked in the above twete is written by a very well-credentialed Lawrence Berkeley National Laboratory researcher... and assumes a perfectly ordered supercell with all the right Pb atoms replaced with Cu, which isn't really something we could perfectly and reliably replicate at scale. Like, we know how to make superconductors out of twisted graphene moiré superlattices too, but that superconducting state is prone to falling apart at the slightest hint of disturbance in the structure (not to mention messy electron-electron interactions) and we're not at a point where we could scale it up comfortably.

Still a cool find and I hope it opens the door for a lot more breakthroughs in the future; but right now it's a bit like calling a bee the next big thing in air travel (if you give it a hundred seats and a pair of jet engines...)

Oh, and! For those wondering why the diamagnetism thing is a big deal: it's because the researchers took it as an instance of the Meissner effect, where a material, upon entering a superconductive state, loses its internal magnetic field and expels it outside. It's up for debate how much of a "superconductor" the stuff the researchers made is (given the low likelihood that they got everything ordered down to the unit cells), but it'll be interesting to see if there's any other phenomenon we might attribute the material's diamagnetic properties to.

Edited by eagleoftheninth on Aug 7th 2023 at 10:05:08 AM

About the "written in word" comment. In what you typically write research papers in then ?

in STEM LaTex is used to provide better formatting

Er, when inserting an equation or other math that would help it format the math better, yes? It's a markup language? (Yes, I have done it myself, but not for a while) And IIRC you can insert a part with LaTex markup into a Word document, I'm pretty sure.

Edited by PointMaid on Aug 1st 2023 at 9:26:40 AM

Opinion: How wildfires in Algeria and California reveal colonial origins of the ‘Mediterranean climate’ I must say though that AFAIK there is no evidence at all that Algeria's climate or vegetation is atypical for a Mediterranean climate zone, and the link between colonialism and fire (mis)management strikes me as tenuous especially since fire regimes aren't a new thing.

...so what about our fires over here, they're brought up and then kinda ignored in the article?

LK-99 update, probably not the end of the story but seems like another blow to its claimed properties: a team from Peking University has reproduced the material and found it to simply be a semiconductor with multiple phases, exhibiting soft ferromagnetic behaviour in one phase and weak diamagnetism in the other. The team attributed the partial "levitation" of the material to a magnetic moment generated by a Cu₂S phase in the anisotropic sample, which displayed diamagnetism while other regions of the sample didn't.

Still an interesting find, though, assuming the team managed to exactly replicate the original. Cu₂S phase transitions were already an active field of study before this thing cropped up; they certainly have a slew of interesting properties, but your everyday pure copper wire has just around 10^-5 Ωm of resistivity and you'd need to go a lot lower than that if you want to call something a superconductor. The original paper points to a thin film form (made by thermal vapour deposition), which I don't think anyone else has tried to replicate yet.

There have been a few other recorded replications at major research labs so far: one at the National Physical Laboratory of India and another at Beihang University. Both did not observe signs of superconductivity, although the X-ray diffraction patterns they showed from the material analysis look markedly different from the one in the original preprint. Yet another replication effort at the Southeast University (Nanjing) found no Meissner effect, although it apparently displayed zero resistance at a relatively toasty 110 K.

This, of course, isn't nothing — at 77 K and above, you can cool the material with cheap liquid nitrogen, rather than the far more expensive liquid hydrogen required below that temperature. But critical temperature and resistivity aren't everything: if you want a practical superconductor, you've got to consider its response to magnetic fields and charge density, as well as whatever mechanical properties you might need to fashion it into a conducting device. It's why our existing practical superconductors (like the Nb-Ti wires in MRI magnets) are often still low-temperature ones that operate below the 77 K barrier.

Edited by eagleoftheninth on Aug 10th 2023 at 7:24:05 AM

It's an opinion article. The author's more invested in pushing a viewpoint than in presenting evidence. The only person she cites is a history professor. No studies or researchers in an environmental field, not even her own field of urban planning. How well-supported this actually is would be better determined by professionals in those fields.

So apparently there are some studies suggesting that male and female brains are more similar than previously expected. The link itself is a The Conversation article, but it does have links to the studies.

^u^

3 pounds of curdled bacon grease in a bone dome.

The Replication Crisis goes WOKE

Can't wait to see those headlines. I'm sure it'll be fun.

Gonna be the party pooper to say that a meta-review based on 30 studies is unlikely to sway a lot of people. Especially since there is a disagreeing study.

Yeah, and this stuff is complex enough that getting a clear cut answer is very hard to get.

It is a very good starting point to examine this topic from going forward though.

Dismissing it or acting like it's not a big potential breakthrough once proper research has been done is pretty ignorant. It might be true, it might not be true, but it's absolutely worth researching more and it doesn't really matter if there's a contradicting study or if people won't be swayed by this study.

Dismissing studies because "people won't be swayed" or because there's an alternate possibility is a ridiculous way to react. The correct way to react is to push for more studies to be done to determine the truth.

Edited by Zendervai on Sep 10th 2023 at 11:02:11 AM

Um ... "there might be an alternative possibility" is in fact a big deal in (Popperian) science. Most theories can only be disproven, not proven. And this is a widely researched topic that's very contentious - thus offers great opportunities for both accidental and deliberate cherrypicking. I think the concerns are entirely fair.

I don't understand your attitude about this.

My position is "hey, we should do more research, this could go somewhere or it might not, but either way, we have learned more about the human brain" and you're acting like that's a weird or unreasonable thing to ask.

If it gets disproven, great, we have learned more. If the alternative gets disproven, great, we have also learned more. There is no downside to researching this.

Going "it's contentious, so we shouldn't study it" is a really fucking amazing way to make sure that nothing new ever gets studied or discovered ever again.

If it turns out that the differences between male and female brains are primarily hormonal and that certain brains are tuned to get certain hormone balances and that's the primary inherent difference, that'd fit into a lot of existing theories about brain development without invalidating trans people at all.

Edited by Zendervai on Sep 10th 2023 at 11:28:38 AM

Oh, absolutely, more research should be done, and it may well be a good starting point (I wasn't aware there hadn't been any studies before this).

Well, I didn't say that more research was useless, but apart from that...

If it turns out that the differences between male and female brains are primarily hormonal and that certain brains are tuned to get certain hormone balances and that's the primary inherent difference, that'd fit into a lot of existing theories about brain development without invalidating trans people at all.

Which sex hormone is produced is governed by the gonads, not the brain. Also, the whole reason why transgender people exist is because the gender identity encoded in the brain isn't always congruent with the hormonal influence. Further, I wouldn't categorically assume that if minor differences between transwomen and ciswomen (or relatedly, transmen and cismen) persist anywhere in the body, this automatically "invalidates" transgender people.

...are you reading what I'm saying?

The gonads aren't important to identifying who the person is. I also directly referenced the hormone mismatch thing. You literally agreed with me but are talking like you're disagreeing.

Edited by Zendervai on Sep 10th 2023 at 3:32:54 PM

The US FDA is claiming phenylephrine, the main ingredient in most over the counter nasal decongestants, does not work when taken as a pill.

Lets add to all of this that brain structure isn't necessarily causal anyway. Often structural or process differences occur due to different life experiences, including different choices made by the individual. Which underlies the fact that many mental processes do not show up on brain scans. Male and female brains could be physically identical at the level of the scan, yet gender differences in mental processing must still be occurring somewhere, and those differences could be (likely are) the result of an interaction between genetic and experiential differences.

Climate extremes likely to drive land mammal extinction during next supercontinent assembly. Mechanically, when supercontinents assemble the inter-continent archipelagoes (like Indonesia and surroundings) that are the main geologic carbon sink disappear and thus global temperatures increase. And they can become high enough to cause mass extinctions.

Well that's gonna be an issue in half a billion years.