The h Bar

@FakeMod To me, google has given out "the command line interface of the quantum bio toolkit"

It says that the electrolyte allows for the now positively charged (have lost their electron) lithium ions to move from the anode to the cathode through the electrolyte, but how the hell does that work, I mean, my guess would be that electrons from the cathode (that have arrived there through the circuit) go through the electrolyte to go back to the lithium atoms?

The whole idea of some "positively charged ions" flowing from the anode (lithium) to the cathode (cobalt) is confusing

11:41 AM

John Rennie is going to 300k in about 1-2 months

12:07 PM

@peterh-ReinstateMonica and probably 1M by the end of the year. I swear his rep is parabolic

12:17 PM

@Jim No, it is unlikely that he will ever get to 1M, without some essential change: stackexchange.com/users/233926/john-rennie?tab=reputation

well, an upside down parabola is still parabolic

In an ideal world, the size of the PSE and the SO would be the opposite

Because physics is important for the future of the Humanity

The details of the 2354th programming language/framework is not

Unfortunately, I can get my $$$ from the second. Only rare people can get - far lesser - $$$ from the first, too.

B. Brekke

@peterh-ReinstateMonica I am not sure I agree with this. But I guess it doesn't really make sense to compare such broad terms

Check this: data.stackexchange.com/physics/query/1171235/… <- it seems, Knzhou will be our next star

@B.Brekke If "future" means survival, then I'm with you. We absolutely don't need physics for the survival of our kind (until the asteroid comes). But if "future" means advancement and progress, then yeah it kind of is vital

@peterh-ReinstateMonica what's on the axes?

I'm not deciphering the code

12:33 PM

@Jim x: time, in months. y: the height of the bars shows the amount of upvotes (s)he got

why is is capped at 100? daily cap?

@Jim Tricky, SEDE is not very good in visualisation, I needed to compansate it on the t-sql level. But it is not so hard as it seems, only SQL is not procedural.

@Jim No. It is because the sum of their relative percentage adds always to 100%.

@peterh-ReinstateMonica Yeah, I can read sql, it's just easier to have it explained

@peterh-ReinstateMonica ah, it's a stacked graph

@Jim There is another problem that stackoverflow is too big for complex queries, except if they are highly optimized. But this optimization means mostly longer code.

@Jim Yes. It shows, how their upvotes of that month distribute among them.

this is all making more sense now

12:36 PM

Thanks! :) :) :)

in that case, yeah he is a rising star

I remember when Floris was like that. Look what happened

his current levels look like mine. And that's bad

@Jim I am now thinking on a query which estimates the skill level of the users, based on their activity. Unfortunately, I could not find anything yet what could be enough fast on the SEDE. Reputation $\approx$ skill level * activity

I believe, something like the Elo-score in the chess, could be calculated. I.e. if X could answer the question of Y, then X is probably at least 1 level higher, than Y. So we create a potential between them, roughly E=1/(1+e^(rep_Y-rep_X))

@peterh-ReinstateMonica good luck with that! Far as I can tell, it may be more like $\text{activity}^2$

We also maximize the highest skill level to 1, and the lowest to zero. After that, we find the skill levels belonging to the smallest potential of the system.

too many confounding variables in this system for something like that. I promise you there is no simple solution to this pattern

12:51 PM

The smallest potential could be found by gradient walking. It is a trivial algorithm in C, but practically impossible in SQL.

I've got it. Something to make physicists smile

$\text{Rep}\approx\frac{1}{2}(\text{skill})(\text{activity})^2$

try that and let's see if it's even close to being something

There's one way to verify it

@Jim Another option: the votes of people having a higher rep, would have a higher value. Thus, their votes would be stronger. Unfortunately, this leads to a bootstrap problem, because we have this chain: votes determine rep. Rep determinate vote strength. This affects rep.

@Jim From that point, we have an eigenvalue problem, in a matrix sized "count of users x count of users"

$dRep=(skill)d activity$

@Jim Fortunately, most fields in this matrix is zero, making the calculation significantly easier, but even that is hard.

12:57 PM

alternatively: $\text{Rep}^2=(\text{skill})^2(\text{activity})^4+(\text{writing ability})^2(\text{activity})^2$

@Jim, it should be differential equation.

@Krishna why should it be a differential equation? It's a better equation. It's a physics equation

@Krishna I think only the left side should be changed to $\frac{dRep}{dt}$

@Jim I believe the problem is not that no solution exist. The problem is that our wonderful company is so smart, that they know from all possible solutions, even before thinking on them, or even understanding them, that they would not work.

@peterh-ReinstateMonica that's a very thin veil you got there

@Jim They ignore us -> we are free to criticize them, if we feel it adequate

1:07 PM

@peterh-ReinstateMonica, yes. I was too lazy to use the \frac and two more terms :P

I'm not going to say that random chance would confound this, because obviously statistics exists in a way that deals with random chance. The issue is that there is no adequate way of confirming a user's skill level in order to test the efficacy of the model. People can simply lie to us. And doing this the wrong way could lead to some people being insulted. Sounds like a lot of egg shells to walk on

@Jim, I guess activity and skill change overtime.

@Krishna activity, definitely. But my skill level never changes. I'm always perfect

:-|

@Jim I think a history of answers to the questions of highly skilled users is an adequate way to confirm that user is highly skilled. Except that exactly the highest skilled people ask the least questions, but the PSE is enough big to have an adequate sample for most users.

1:10 PM

@peterh-ReinstateMonica if true, then the ratio of answers to questions would be a good indicator. The higher the better

But that is a function of activity too

That would be infinity for a good many people

Those who have asked no questions.

drop the low tier of answer numbers. How many people with over a hundred answers have no questions?

@Jim No. Only if the answers are for the questions of more skilled users.

Qmechanic, for instance

2700 odd answers, 0 questions!

@Krishna gotta love the law of exceptions. It always applies without exception

1:12 PM

:)

@Krishna Even his skill level could be estimated by checking the skill level of the users he could answer. Of course we can have only a lower estimation on this way.

@peterh-ReinstateMonica doesn't that beg the question? To find skill level, check against users with known skill level

But, Jim, I guess Qmechanic will have a really high activity

@Jim No, only complicates things.

And a really high skill

1:15 PM

@Jim Do you know how the "elo rating" works in chess?

@peterh-ReinstateMonica nope, not a chess player myself

I supposed you could numerically integrate the whole thing. solve the system simultaneously

@Jim All players with a FIFA registration have an elo score (today it is called "glicko score" with a more complicated, but essentially similar algorithm). This supposed to estimate the strength of a player. If you play a game with an opponent with higher score, your rating grows more, as if you win a weaker opponent.

@Jim The system is tuned so that 100 point of elo difference supposed to have a 67% winning probability of the player with higher score. The world champions have an elo rating $\approx$ 2800, regularly playing fifa players start at about 1400

but it's fundamentally easier to determine the skill levels of people in direct competition. You let them play it out in one way or another. We don't have competition here, only cooperation. A low-skill user can still answer a high-skill question with help from the poster. I've done it myself for a question in a field I have no knowledge of

@Jim This system can be applied also for other games. Btw, the difference of an Elo-rating between the beginner and the world champion, is a good estimate, how complex is the game itself.

I mean, it's no Go, but it is an incredibly complex game

1:22 PM

@Jim Yes, such a system would have a significant, possibly unsolvable disadvantage that asking a question would result an unavoidable decrease of the skill point. But now that no "skill point" or any similar exist on the SE, and thus the users did not considered it while asking questions, it could be still useful to estimate their skills.

I think it's for the best that there is currently no skill ranking. The best laid system will always have a way to game it. Even without that, it might be more detrimental. You said that asking a question in this case might decrease score. Our site would be the worse if we disincentivized top-tier users from asking questions

Fix: the chess organization is not FIFA, that is for soccer. Instead, it is FIDE.

@peterh-ReinstateMonica Yeah, I was thinking that, but I don't know enough about chess. I thought maybe it's a coincidence

@Jim What is in the world of professional research? There are "impact factor", obligaroty publications often with not very high quality (as said by other scientists), unfair reviews, unaccountable hidden reviewers, academia SE is a nice site to read

@peterh-ReinstateMonica yeah, I don't much like that system either. Intentional obfuscation of science should be loathed, but it's currently common practice in order to get published

I gotta say, it works too. I saw it done with my own work during my degree. It wasn't much to begin with. I wrote it clearly and understandably and it came across like nothing. My supervisor took the same thing, wrote it so I pretty much didn't understand it, but it seemed great. Very publishable

makes sense why they do it too. They are pressured to put out a lot of publications a year. Not many people have enough work worthy of publication in a year

1:32 PM

@Jim I think what really dangerous, if useful papers and results don't get published, or don't get attention. What do you think, is it possible that there are important results, which were simply forgotten because they failed the reviews?

@peterh-ReinstateMonica yes, but I'd wager they are few in number. Odds are there are more useful works that got through but are never used because nobody can follow them well enough, or they are simply hidden amongst the trash

@Jim What if they could be found by a well-directed AI?

I'd be happy? I am skeptical about such a thing, however

@Jim There are various secondary parameters. The history of the publisher, the history of the people with them he had a cooperatively written paper. His field of research, how hard is it, how does it connect to other fields. I think, there are also forgotten papers re-discovered lately

yeah, all too much for me to worry about

1:43 PM

@Jim Considering that the people obfuscating the results are very highly skilled and focused, real humans, it is likely very hard, but still not impossible.

agreed

@Jim An initial sample is needed about the real trash (easy to collect), and about this re-discovered diamonds (harder, but possible). Then an adaptive NN would check all the publications

I think it would find many diamonds, too.

maybe for now. But the trash would eventually adapt. There's literally a selection pressure for it to adapt

"adaptive neural network" means an NN, where not only in its weights, but also its structure can be modified in training.

@Jim Ok, but scientists have a fixed time. They read the papers of other scientists. They need to find out, whose papers do they focus on. What if they get a tool which grabs the diamonds for them?

obviously that would be good

1:56 PM

@Jim Imagine, you check 1000 papers, and set a real value between "trash" or "diamond" on them. And then a program says the next 1000 papers, from which it thinks, you will most likely consider them diamonds.

good theory, fraught with complications in practice

@Jim I need all the metadata of all papers of all professional scientists, where is it? arxiv.org ?

Q: Are "Do this calculations for me" question allowed here?

no clue. that'd be a good start

Physics Meta

2:15 PM

0

I have a problem to be solved (here) and an answer that brings all the necessary calculation steps (here). I can't do the calculations myself because I don't have enough knowledge and skills. I went through cited answer seven times and still fail to even start. Does this mean that I should close...

user434058

2:39 PM

Hey folks, should PSE have a chatroom similar to MathSE's CURED chatroom (C: Close, U: Undelete, R:Reopen, E: Edit, D: Delete)? I am proposing such a chatroom because, there are many days when I run out of close votes. If I see a question ought to be closed, then the only way left is to leave it up to other members. If we had something simikar to CURED, I'd just drop a message linking to that question, requesting its closure...

user434058

Same goes for deletion, undeletion and reopening. Editing doesn't really require external help (except a non privileged user might want to bring something to attention for immediate editing).

user434058

Moreover, having an extra chatroom has almost no cons. Even if this idea fails, we would have nothing but a frozen chatroom. But if i1 works, we would be ab!e to close the eternal intake of off topic questions way more effectively.

user434058

The reason why I am asking here is because the chatroom needs to be maintained by the community. I can't just create such a room and keep on posting there alone. If considerable number of people are interested, then I think it's worth a try.

user434058

One very recent example which I would like to post in that room if it existed: physics.stackexchange.com/questions/554967/how-to-find-r2

user434058

I've run out of close votes. I can do nothing except to downvote, or maybe comment...

2:48 PM

I think you can copy these to a question on Meta. Sounds like a good idea. Community interest can be measured using the votes.

user434058

@GuruVishnu Alright. I've got to go for dinner. I would do it after an hour. If anyone else feels like posting this on my behalf, feel free to do so.

Imagine if guys on the ISS used a giant 3D printer to expand the ISS itself lol

Archer

3:03 PM

Thanks @terdon, Can you delete these messages for privacy reasons?

terdon

What messages?

And you're welcome. I have also contacted an SE employee to see if they can merge the two chat accounts.

Archer

@terdon The chat messsgaes

Like the one about my old account

terdon

@Archer Yes, that much I understood :)

I can delete the conversation if you like. However, please don't do this again. There was nothing "urgent"! Just raise a flag and wait. Saying you urgently need a mod makes it sound like you are being attacked or something.

21 messages deleted

→ 18 messages moved to Trashcan

There, done.

Archer

@terdon Oh. Noted, thanks again.

terdon

No worries. Have a nice day!

Q: Negative value of $dq/dT$ in a polytropic process

3:37 PM

1

Consider a reversible polytropic process $PV^x=K$, where $K$ is a constant. We can easily derive , By differentiating this and using the gas laws, that for such a process, $PdV=(nRdT)/(1-x)$. Consider the Firs law for a reversible process: $dq=du+P_{gas}*dV$ (since $P_{ext}=P_{gas}).$ Substituti...

thermodynamics ideal-gas

I am having a bad case of brain-pain.

why is it not showing the "heat" tag despite the fact that i added it? — satan 29 25 mins ago

wtf, someone just called my work phone number and shouted at me to stop using his WLAN

@satan29: That's because heat is a synonym for thermodynamics tag.

user434058

@ACuriousMind It was me ;P

More details: physics.stackexchange.com/tags/thermodynamics/synonyms

3:42 PM

@FakeMod Very impressive German speaking skills you have there, then!

user434058

@ACuriousMind Das tue ich definitiv

@GuruVishnu Now, If you can start helping with the answer to the question...:P

@satan29 Please don't post your questions here directly after you asked them; interested people watch the main site anyway, and if everyone did it, the room would be flooded with new questions.

user434058

@ACuriousMind BTW, what about the kind of chatroom I suggested above? Is it a good idea?

Hi @ACM♦. When you're free can you please add "This comment attempts to answer the question instead of asking for clarification or improving the post" in the flag option? It would be nice compared to typing the same thing on a custom mod flag :-)

user434058

3:46 PM

@ACuriousMind I presumed you'd post a link of the message which linked to the message which linked to the message which linked to...*(hundred iterations later)* message that you shouldn't post your questions immediately after you ask them :-P

@FakeMod I don't like these kinds of rooms because I think they are effectively a way for some users to "extend" their close votes beyond their daily number of flags. I'm not convinced it is beneficial to let users dominate closure decisions like that.

@GuruVishnu I'm afraid moderators can't add comment flags

just use "no longer needed" if you don't want to type a custom flag

user434058

@ACuriousMind Yeah, I expected someone would bring that up (though I expected someone who doesn't like closing questions would bring that up). But, TBH, I think your argument is flawed. The chatroom only directs people to "close-worthy questions". It depends on each individual whether it's worth closing. Thus there isn't any kind of extending my votes. And it would be a --shame-- problem if a "close-worthy question" did not get closed only because of lack of it's exposure to the people who can VTC.

@FakeMod Yes, but by deciding whether or not to post a question there you can influence which kind of "close-worthy" questions get exposure and which don't.

I mean, exposing close-worthy questions to people with the ability to close-vote is exactly what flagging and review queues are for

user434058

@ACuriousMind I mean I'll post all the ones which should be closed but aren't yet.

Such rooms are in my view just a separate flag/review mechanism that circumvents the restrictions that are intentionally part of the existing flag/review mechanism

user434058

3:53 PM

@ACuriousMind Yeah, exactly. The chatroom might seem redundant for the people who regularly visit the review queues...

user434058

@ACuriousMind I don't really understand what you mean by "restrictions".

@FakeMod The maximum amounts of flags/votes/reviews per day.

user434058

Though, I am slowly seeing redundancy as a con against creating such a room.

@FakeMod Sooo...why would anyone choose to prefer to use such a room instead of just raising a flag or going to the review queue?

user434058

@ACuriousMind Ah, the maximum amount of flags/votes doesn't really change. But yes, you can "review" much more posts with using this room than youk can by just using the review queues.

user434058

3:56 PM

@ACuriousMind Quicker action? :-) That's the only benefit I think this room can have.

If there's enough people in that room to continuously get quick action, why wouldn't they just use the review queues to speed up review instead?

@ACuriousMind I understand. I only wanted to ask about the comment, (why the "heat" tag isnt showing). The next part (where i asked Guru vishnu for an answer) was a joke...

user434058

@ACuriousMind Yeah, I am seeing it all now :-)

How do Lithium-ion Batteries Work?

5:21 PM

►

It says that the electrolyte allows for the now positively charged (have lost their electron) lithium ions to move from the anode to the cathode through the electrolyte, but how the hell does that work, I mean, my guess would be that electrons from the cathode (that have arrived there through the circuit) go through the electrolyte to go back to the lithium atoms?
The whole idea of some "positively charged ions" flowing from the anode (lithium) to the cathode (cobalt) is confusing

@JingleBells What exactly do you find confusing about the idea of a positively-charged ion moving from anode to cathode?

@ACuriousMind I didn't know that there was such a thing as positive ions flowing. I thought only electrons could be moving and the absence of electrons is what makes something positive

"Only electrons move" is simply only true in metal conductors, not in general

positive ions in a solution obviously do flow..

In a metal conductor, There are no "free protons" i.e all the protons are bound.

In the video I sent, it says that after the lithium atom gets rid of its outer electron, it becomes a positive ion. Why is that? Shouldn't it be neutral?

5:28 PM

It was neutral before it lost the electron, so it's positive afterwards.

Hmm, I thought that because it wants to get rid of the electron, it's more stable without it, making the afterward state neutral. But I guess no one cares about what the poor atom wants :D

the truth hurts

I thought that atoms that want to give their electron/s away are negatively charged

Alright so in a li-ion battery, as the lithium side starts getting rid of its electrons through the circuit, the now positively charged lithium atoms physically move from the anode to the cathode through the electrolyte, which doesn't allow electrons to flow through it making all the still non-positive lithium atoms stay there until they get rid of their electron...

^ is that right?

@JingleBells You have to think about this more in terms of chemistry - the electrolyte is much like a solution of lithium salt. Ordinary table salt - natrium chloride - is a ionic cyrstal whose structure is that of ions (positive natrium and negative chlorine) sitting in a lattice. When you put it into water, the lattice falls apart and the individual ions get surrounded by water.

You don't need to do anything special to "make" the natrium lose its electron - it has already given it away when it formed the salt because of the "atoms want full or empty outer shells" rule of binding

Got it, brb

user434058

6:46 PM

Yo!

user434058

Ne1?

user434058

Lol

user434058

\o/ Can anybody hear me? \o/

user434058

Nvm

Charlie

8:14 PM

Hello

9:56 PM

Recreational SEDE research: I found that quarks are more popular than leptons.