Hacker News Reader

Comment by versteegen | Hacker News Reader

Very interesting comments on the paper by Prof. Michael S. Fuhrer https://nitter.net/i/status/1688755932275384320

> But I think they buried the lede a little. Ferromagnetism is novel and unexpected in this material system, and might be interesting. But strong diamagnetism even more so

> Even if the diamagnetic fraction is the entire sample (appears less) then it would be the second-strongest diamagnet known (and pyrolytic graphite's diamagnetism is very anisotropic). In both Bi and graphite, diamagnetism results from unusual band topology. It's not common

> Overall, some evidence that as-synthesized nominally Pb_10-xCu_x(PO4)O ("LK-99") is magnetically quite unusual, with different fractions showing soft ferromagnetism and strong diamagnetism

View on HN

LK-99 may not be a superconductor, but it will always be super in my heart.

There are 2 things in favor of the Korean team

- Hyun-Tak Kim is unlikely to ruin his career and legacy for something careless and frivolous. But stranger things have happened, so lets assign a 10% probability to give some benefit of doubt to the team.

- The various DFT papers show interesting flat band structures. But DFT is an approximation and also they do not take into account electron electron correlations. So lets assign another 10% probability for this support.

This crude estimate would give a 20% chance of RTSC. Rest has to be resolved by actual demonstrations, primarily from the Korean team themselves, and then from reputed Western researchers/labs.

I too like to assign probabilities to my vibes. Much more legitimate.

It’s the Bayesian way.

Common in tech: “95% of our users wont care if we make the product worse by…”

That's falsifiable though, in a way the other examples are not. You could sample the population of users after the change to the product

Reminds me of how Data in Star Trek would say things like "There is a 79.85 probability of success".

I mean, maybe it is possible to assign probabilities to future events that you have never seen before, but somehow I doubt it (with 12.88% likelihood).

>but somehow I doubt it

You doubt it? That means you're assigning some underlying probability to the event (not) occurring. Why does it seem strange to you if people are explicit about their priors?

It's not that it's strange, it's that it is transparently silly to claim to precisely quantify in the absence of anything resembling sufficient information for the problem to be treated probabilistically.

Ya what if you just don’t know

Any jackass off the street can just not know things! If you want to get invited to the in-crowd's house parties, you're going to need to do a lot better than that.

How about this? I keep a running probability (e.g. a 32bit float) for the successful outcome of each future event I have absolutely no idea about. At first I make it 50%, but I gradually adjust with each result, such that I aim to minimize my bias. It might sound silly, but at the minimum it would encode some information about the kind of events I'm typically asked to predict. And I do expect it could end up something like 0.5642635 for a particular time in my life.

"Not even wrong." An event about whose outcome you by definition have no information ("I have absolutely no idea") is an event to which you cannot assign any probability, including by assuming it's a coin flip and then treating the assumption as axiomatic. It encodes no information whatsoever because there is none to encode, and it biases all future results because you're averaging over a range that includes "data" you made up.

I'm having trouble following your reasoning. "Not even wrong" typically is used to refer to something unfalsifiable, but I specifically provided an empirical process and even a mechanism to explain why it might work - a person in a given position would likely be asked to make predictions with a different base likelihood of success than a person in another position.

In any case, it is precisely my argument (and Scott Alexander's) that there are no events to which it is axiomatically impossible to assign probabilities.

A prediction based on no information is definitionally unfalsifiable.

I'm well aware of the nature of the argument, having been an SSC reader since long before the whole Cade Metz kerfuffle, and still being an ACX reader now - admittedly these days more to see what Alexander is on about lately; it's been some time since I've taken him seriously. A major reason why that's the case is because I've yet to see from any source a substantiation of that argument which is sustainable in the absence of a lot of handwaving. Granted, nobody waves hands like Scott Alexander! That's a lot of why I still find him so entertaining. But the handwaving is still handwaving.

I think it's the excessive precision that's funny.

I think this culturally comes from lesswrong and it really makes me laugh every time I see it

Yeah, Scott Alexander wrote a whole article about how people should use made up fake statistics instead of simply saying "I don't know"[1].

[1] https://slatestarcodex.com/2013/05/02/if-its-worth-doing-its...

Not always. "I don't know" is identical to saying "I have a uniform prior". In the particular case of LK-99, my prior is perfectly uniform - I know absolutely nothing about the subject matter and almost everything I read on the topic feels way above my head. As I refuse to be influenced by experts (or "experts") until there is some sort of consensus, I have absolutely no good reason to say anything but "I don't know".

A perfectly uniform prior suggests that you think that it's easy to make a room temperature super conductor and that people have made them before with equal likelihood to it being hard to make a room temperature superconductor and people haven't made them before, doesnt it?

I don't know much about superconductors, but I do know that people have been trying to make them work at room temperature, and generally failing

> Hyun-Tak Kim is unlikely to ruin his career and legacy for something careless and frivolous.

you came with presumption that this man knows & understands the subject matter. that is a very bold assumption given the mounting evidence against such brief.

> so lets assign a 10% probability

why 10%? not 0.01%? because of his "prof." title or previous publications? Surely that won't change the course of nature I thought?

> and then from reputed Western researchers/labs.

what makes you discount inputs from Russian, Chinese, Japanese researchers?

You seem to have some really wired brief here, get some help I say.

> You seem to have some really wired brief here, get some help I say.

I googled "wired brief" and this is what I found:

https://www.ebay.ca/itm/303994118271

I swam those a lot.

Sorry for the typo, statistically you make more typos when you write in a foreign language. feel free to make fun of it, totally fine with me.

It's not my native language either.

Sorry if you felt made fun of.

I've seen this on here before. Guys convincing themselves that they're being rational and you're being emotional - because they put little numbers besides their feelings and perform some calculations to produce a percentage that "proves" their theory about Antivax stuff, Putin/Ukraine or whatever is credible.

It's a shibboleth in rationalist circles who convince themselves/others that they're doing Bayesian inference in their heads.

It comes from lesswrong/rationalist circles.

Best to ignore people once you have identified that they are on the wrong side of the Dunning-Kruger curve

No, let's not. I have seen examples here on HN where leading experts in the relevant field have been accused of Dunning-Kruger (I recognized the usernames, the accusers obviously did not). Such accusations are just namecalling and destroy any civilized debate.

Should we be reasoning from last usages of a phrase that you didn’t like or the particular context here?

Anyone who thinks rationality and emotion are mutually exclusive, hasn't understood half of what any of the big names in that area wrote.

Which isn't to say you or the other replies next to mine are wrong — any memes that get shared also get misunderstood, including attempts to be… less wrong.

(Putting numbers on my uncertainty has mainly made me aware that I'm bad at it, which is useful to be aware of even if it doesn't make me better at it).

>their theory about Antivax stuff, Putin/Ukraine or whatever is credible.

Your politics are revealed with your choice of examples here.

Who needs a decision-making mental model when we can just trust what the experts tell us about these things, or maybe "trust your gut"? That's never failed.

That's a false binary. "I don't have enough information to form an opinion here" and "I feel like that guy's probably full of shit, though" are in no way mutually exclusive.

I agree with the main claim you are making here. That decision-making models are important an aspect to minimizing the chance of failure when considering decisions. Nothing I said is an attempt to contradict your main claim.

> Your politics are revealed with your choice of examples here [Antivax stuff, Putin/Ukraine or whatever is credible].

I understand that antivax has been claimed by the mainstream right (there are antivaxers on the far-left but they have limited influence), but it feels like I'm living in some bizarro world that people see the efficacy of vaccination as being "political." It feels like I'm living a ham-handed allegorical story about dangers of irrationalism.

> Who needs a decision-making mental model when we can just trust what the experts tell us about these things, or maybe "trust your gut"? That's never failed.

I'd argue that trusting your gut or trusting experts are both decision-making models. They both work well within the right context and fail outside those contexts.

* Trusting your gut is often the right option when you have to make an immediate decision and you don't have time to weight the various options. Something weird is happening on the highway ahead of me should I break now? I have 0.3 seconds to decide.

* Trusting the experts works if the experts are experts in that field and that experts in that field have a long track record of correct predictions and the experts are talking to are in fact experts in that field and have access to the level data which has rendered correct predictions in the data. I'd assign a near 100% probability to a statement by an astronomer that tomorrow night will be a full moon over Toronto, I'd be less likely to assign a high probability to a physicist saying that this new experiment they have will detect sterile neutrinos.

Even those fields in which I am an expert in, I weigh the claims of other subject matter experts when I do not have the time to do the necessary reading and work. The biggest problem with trusting experts is determining is a particular "expert" is actually an expert in that field when you are non-expert in that field.

> Your politics are revealed

My beliefs and my politics are pretty transparent in my comment history, I'm not trying to avoid them being "revealed" whatsoever.

> Who needs a decision-making mental model when we can just trust what the experts tell us about these things, or maybe "trust your gut"? That's never failed

Not me? I saw people applying the methods we're talking about to convince themselves that the likelihood of their pet conspiracy theory is true is around the same as a coin toss. You can reach bone-headed conclusions if you're determined to do so, whether you use some decision-making mental model or not.

> you came with presumption that this man knows & understands the subject matter. that is a very bold assumption given the mounting evidence against such brief.

Not OP but "this man" has published enough papers on superconductors[0] that yes, he absolutely deserves the benefit of the doubt.

[0]: See e.g. https://scholar.google.com/scholar?hl=de&as_sdt=0%2C5&q=hyun... or https://scholar.google.com/citations?user=_P8mux4AAAAJ&hl=de...

Do you work in the field? Those papers are ridiculous and the “theory” parts literally do not make sense

making a few PDFs publicly available doesn't change the course of nature. he is now in the position to fully explain to the world what is going on here as no one seem to be able to reproduce what he claims.

given such facts, it is totally reasonable to question his expertise on the concern subject. you are free to judge people purely based on how much they publish, I totally respect that.

- Nothing against Russian researchers, but apart from Iris who is somewhat anonymous and doesnt have the required equipment to create good samples, I havent seen anyone from there interested in performing expts on this

- There have already been some retractions from China after the initial replication claims. I get the feeling they have been overeager about this to prove themselves. Maybe if they approach this with cooler heads, they could be depended on more.

- When i said western labs, i spiritually include japan, taiwan, south korean labs in that, since they generally have similar practices and rigor (even if geographically they are in the east)

> When i said western labs, i spiritually include japan, taiwan, south korean labs in that, since they generally have similar practices and rigor (even if geographically they are in the east)

It's difficult to communicate with you if you just redefine common expressions however you see fit. It's like saying "by left, I mean right." Just... stop.

We can debate about expressions/terminology, but these three countries are very very closely aligned with the US. Ofcourse its mutually beneficial.

A joke a military contact cracked once is that the only diff between these three and guam, is that guam is officially recognized as US territory.

Make of that what you will.

> When i said western labs, i spiritually include japan, taiwan, south korean labs in that, since they generally have similar practices and rigor

Are you implying that the west is as corrupted as Japan? That is not something I can agree with.

In case you got yourself isolated from daily news for too long, below is just some recent news regarding those common practices in japanese labs.

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

most japanese major groups are falsifying their various type of data - just look at recent news since 2015

Hitachi admitted falsifying data on brake testing https://www.asahi.com/ajw/articles/14508789

More fraudulent testing found in Mitsubishi Electric https://www.asahi.com/ajw/articles/14630514

Accounting fraud by Toshiba https://asia.nikkei.com/Business/Companies/Toshiba-s-chairma...

Kobe Steel admits data fraud went on nearly five decades https://www.reuters.com/article/us-kobe-steel-scandal-ceo/ko...

Lets not drag Japan into this. They have very high standards in research despite the few examples you gave here, some of which are not even science related.

As a widely accepted measure of this, you can read about the many nobel laureates from japan.

Anyways lets keep politics out of the discussion. It was not my intent anyway, in case you perceived it that way.

Repeat after me: Flat bands do not imply superconductivity. DFT calculations cannot be used to predict superconductivity. DFT is a single-particle calculation. Superconductivity is a multi-particle phenomenon.

At most, the preprint(s) you're referring to suggest that maybe (under their unverified assumptions) electron-electron interactions could lead to interesting physics in that material. It provides no evidence for what that physics looks like and says nothing about what temperature these things will occur.

High temperature superconductivity is not well understood and we do not have the theoretical tools to make quantitative predictions about it. At best we run dodgy simulations, squint at the resulting plots, and say "hm, that's interesting".

That's not how probabilities combine.

You are right, but probability estimation of possibly novel phenomena is an ill posed problem.

So either you do not model it at all, or come up with some mental model of what probability you are comfortable with and due to which factors; the factors being more important than the final number.

The exact numbers don’t matter, but your post indicates that you seem to have the wrong mental model of how to adjust your credences. The probability of each factor decreases the overall probability, not increases.

Alright lets do some calculations. Feel free to dissect the assumptions.

K event = Kim says Material L is RTSC

D event = DFT says L is RTSC

S event = L is actually RTSC

we have assumed P(S/K) and P(S/D) are each 0.1, though we could have chosen other numbers for them as well.

We want to estimate P = P(S/(K and D))

P = P((K and D)/S)P(S)/P(K and D)

Assuming Kim and DFT are in the business of making positive predictions, they always get it right when L is actually RTSC.

so P(K/S),P(D/S) and P((K and D)/S) are all taken as 1

hence P = P(S)/P(K and D) = P(S)/(P(K)P(D/K)) = P(S/K)/P(D/K) = 0.1/P(D/K)

(similarly, P = P(S/D)/P(K/D) = 0.1/P(K/D))

But ofcourse we dont know P(D/K) or P(K/D). We could check historical data on how often D aligns with K, a messy exercise at best. Say they dont perfectly align, then the conditionals are less than 1,and P>0.1. Even intuitively when K (or D) gets additional support in the form of D (or K), your P should increase, not decrease.

If we assume D and K align on average, then P(D/K) or P(K/D) is 0.5, and we get P = 0.2.

You may estimate everything above differently, thus getting a different P. You can also come up with your own way of modelling this. I came up with my particular estimate to understand how frequently should i follow the news, and care about the whole thing. You should model it according to your usecase.

What? Your model doesn't make any sense if you don’t know how to combine probabilities.

Furthermore, you can’t just say “I understand things semantically different than everyone else talking about probabilities so when I say the probability of two events happening is 20% I actually mean something completely different and my math works this way I invented to describe why my messy naive intuitions about probability don’t match the reality of how probability works”.

dude you so do not know what you are talking about, the GP is talking about basic conditional probability rules lol

That's not what GP means - even if you assume they're independent variables, 2x 10% probabilities combine to a 1% ('10% of 10%', they multiply, not add) probability of the total outcome, not 20%.

Huh? I think he's saying OR not AND. Why would two separate pieces of evidence make the whole less probable, that makes no sense, whether you spell out the whole thing more formally or not.

So if I find 10 people that claim, each with a 10% likelihood of being true, that the dark side of the moon has a scar that looks like Pikachu, then it’s 100% true?

That doesn’t make sense either. Seems like someone is falling prey to an intuitive fallacy of probability.

The weird model is just wrong in the first place. The commenter we’re discussing conflates the probability of two people saying something with the probability that what they say is true. So yes, you have to model the situation correctly in the first place.

No,even though the 10 pikachu fans assess independently, their estimations will be correlated. As you may already know the overall estimate wont be 100%, rather about 65%. The formula when the assessors are known to be independent, is simpler and has already been indicated by another commenter, P(A1 or A2 or A3 or ..An) = 1 - P(not A1)P(not A2)..P(not An)

On the other hand, if those 10 were engaged in complete groupthink (so no additional information beyond the first guy), the overall estimate would remain 10%.

In general, the answer would lie between 0.1 and ~0.65 depending on how their estimates influence each other.

Of course you don't add probabilities, but for small probabilities it's an ok estimate. The chance of getting a single heads in N coin flips is one minus the probability of always getting tails, so 1-P(tails)^N. If P(heads) and N are small (e.g 0.1 and N=2), adding the probabilities is a perfectly reasonable estimate, just plug in the numbers and check for yourself.

Ok yeah I think maybe I misunderstood the original argument. But those are absolutely not independent (which was probably the repliers point, unless we made the same misreading).

They are only 1% off. They’re trying to say “there are two independent 10% probability events that imply RTSC”.

You can’t add them, but you can multiply 90% by 90% and get an 81% chance of not RTSC, or a 19% chance of RTSC according to this model.

1pp or 5%

> Hyun-Tak Kim is unlikely to ruin his career and legacy for something careless and frivolous.

Everyone is suddenly an expert in HT Kim's character who didn't have any idea who he was a month ago.

And this definitely is a sort of "black swan" event in the same sense that major airline crashes are absolutely atypical of normal air travel. Inherently this viral media event is going to involve atypical constituent parts.

The idea that we could have found some of the most overconfident and underqualified material science researchers out there, who could not realize they were committing career suicide, making these claims isn't very paradoxical at all.

Most aircraft maintenance is exceptionally high quality. You're going to find a lot of bad maintenance in the fatal air disasters that hit the headlines. The FAA doesn't approach an air disaster by assuming the good intent of everyone involved with the maintenance of the plane, and that their inherently understanding that lives are in their hands if they make mistakes should necessarily diminish the likelihood of maintenance issues. They assign "0%" significance to that kind of things and instead just investigate what caused the crash. If it was bad maintenance then the operator and/or the mechanic doing the maintenance take the hit to their reputations.

Same thing here.

Coincidently this is the first time of hearing of nitter.net, do I need to open an account there too?

It's just a read-only Twitter mirror.

It "just" makes Twitter readable to the Internet at large.

"At large" is a strong term given the average person (even the average Twitter reader) doesn't know what it is ;)

I think you misunderstood. Twitter is almost unusable without an account, and the website is very slow. Nitter makes it usable for the majority of us with no twitter accounts, and/or relatively slow devices.

Also, you can host your own private nitter instance and follow accounts using rss.

https://github.com/zedeus/nitter

Well, time to make xitter.net then.

Or nix.net

I'd join that.

(my name is Nick)

Reply on news.ycombinator.com