00:00 - 17:0017:00 - 00:00

5:00 PM
Or perhaps I shouldn't call it a "policy", but it is a reflection of the way the moderators handle flags.

user54412
I might be the sole non-mode high-rep voice of opposition here, but I'm rather concerned with where this might take us. It seems we've decided that downvoting into oblivion is insufficient, and that we'd rather curate the site by deleting (with no evidence to the average person) anything we disagree with.

It is also frequently "handed down" from SE that we shouldn't delete posts for being wrong. I'm not sure of a publicly viewable source on that offhand, but I'm sure it's somewhere on MSE.

user54412
Is this a Q&A for "active researchers, academics and students" or is it a small and elite cabal who dictate what is and isn't physics to the masses?

Anyway, this brings us to the end of our official chat session! Though I believe we will keep going for a while discussing these issues. For those who are leaving now, see you again in two weeks for the next session!

@ChrisWhite it's a large and peer reviewed cabal who dictate what is and isn't physics to the masses

user54412
5:02 PM
We already have an issue with the dichotomy between the few high-rep answerers and the many low-rep askers, and this threatens to broaden that without even acknowledging that it is doing so.

@DavidZ not familiar but guessing, it sounds like SE maybe wants "common bad answers" to be downvoted and it can actually be a guidance to readers (vs deleting them and nobody seeing it). "we've heard of this and agree its wrong" etc

@JohnRennie Not that large, look at how many people actually do reviews, VTC, vote to delete etc.

user54412
Note that at least wikipedia has an edit history viewable to everyone.

@ACuriousMind potentially large

@ChrisWhite I see your concern, and I think we might be trying to solve the problem in the wrong way

5:04 PM
By the way, this is relevant:

### Discussion between David Z and Emilio…

Imported from a comment discussion on meta.physics.stackexchan...

The best solution to garbage posts would be to make downvotes actually count
2
There are users on this site without a single answer with positive score and yet they accrue more rep every day

user54412
@JohnRennie Have you ever heard about those people who've been personally banned from the arxiv for disagreeing with its owners? This is reminding me of them. Except I'd sooner delete bad content from the scientific community than from the explain-science community.

user54412
@ACuriousMind Can't disagree with that.

I could live with egregiously wrong posts staying if they wouldn't effectively act as net rep generators regardless of how bad they are

@ChrisWhite the point is that I see this site as part of the science community
2

5:06 PM
@ACuriousMind how is that even possible?

@Obliv Luxembourg city centre

@Sanya One downvote takes away 2 rep, but an upvote grants 10

and that day is a fine sunny sky where colors are vibrant

In my ideal world an eager young physics student could believe everything they read on this site and use it in their exams.
2

@ACuriousMind you first need people to upvote crappy answers then

5:07 PM
@Sanya Yes

@secret :D makes me want to visit

Other cranks, confused people, sockpuppets, it happens

user54412
I feel like the high-rep users are tired of seeing their downvotes do nothing. But I think making downvotes universally do more is better than giving an elite few more power. Basically what's being proposed is giving some users uber-downvote privileges. Are we so sure we want to go down that route?

@Sanya you'd be surprised how often that happens

:( given the amount of simple calculation&simple research questions on this page that get answered before they are even put on hold, maybe I shouldn't be surprised by weird voting behaviour either ...

user54412
5:08 PM
got to head out and do... the real science I'm paid to do as it turns out ;)

@Sanya yeah, the best thing we can do for the moment is try to get those holds put on as quickly as possible

That's true. But in addition to that, in art theory (especially in sculptures and installation arts), you can give a sensation of motion (and hence an element of time as defined in sculptures) by capturing a moment of something that is moving

Hence the paradoxical mix of motion "standing still"

@ChrisWhite see you

BTW this is what I was doing while forgetting about the chat session. Another attempt at proselytising to the masses:
1

Lorentz contraction is easy to understand once you realise that it is not a contraction at all. Instead it is a rotation and the length of the object, or more precisely its proper length, doesn't change at all. To see this take the usual example of a rod of length $2a$ aligned along the $x$ axis...

Oh, by the way, is there interest in resuming the discussion on history questions now?

5:12 PM
@ChrisWhite No, I'm not sure about that. But there's also the fact that the VLQ review queue already deletes answers that don't fulfill the "gibberish" criteria

@0celo7 See my comment to John Rennie above

@DavidZ I've just reread the meta post, and it looks all very sensible. Is there much more to discuss?

@DavidZ I've followed the discussion earlier silently because there seems to be a consensus that we need some questions to be off topic - can you give me a hint as to what we want to avoid in the first place? Maybe that makes obtaining an off-topic criterion easier afterwards too

@JohnRennie We spent 40 minutes on it today ;-) The gist seems to be that some people think the specification of which questions should be off topic is not sufficiently clear.

some people = me, apparently ;)

5:15 PM
People who spit gum on the ground are worse than Nazis and ISIS, honestly.
At least those guys have goals

@Sanya well, if I could give you that, I think we would have a criterion already ;-) What we are trying to do is to clarify the border of our site's scope.

@DavidZ ok, let me put it that way (playing the bad guy a bit) - what is the worst thing that can happen? Someone asks a question here which historians could answer better and doesn't get good answers/any answers at all. So what?

@ACuriousMind oh, I thought you weren't alone...? I mean, I kind of agree. I don't think the description given in Emilio's answer is quite clear enough, although the underlying idea seems quite sensible.

Is this a physics question? I got shouted at the last time I voted to close a question on the grounds that meteorology isn't physics.
1

I am residing in New Delhi (pardon me for any irrelevant data I might include), and I noticed a really interesting thing. It's an average 30 degrees Celsius out here, and yet, most/some weather forecasting media are reporting the conditions as 'foggy'. Is there a way to describe why this is ...

@Sanya lol youre never gonna make a good administrator with pointed questions like that... ("bikeshed", anyone?) :P

5:19 PM
@Sanya this is not the sort of issue where it's useful to frame it in terms of the harm that could be caused by making the wrong decision. We simply need to make a decision, and be able to explain it to future readers clearly.
@JohnRennie I'd consider it off topic as meteorology, not physics

@DavidZ anything goes? I seriously doubt Physics SE is going to be flooded by questions about hard core history

Example of a sculpture using time as an element (Photographed in Musee' Du Louvre). The sensation of motion is implied

@vzn not trying to be one luckily :D

@DavidZ I think the people doing "environmental physics" might disagree?

5:22 PM
@ACuriousMind I did have an "Air Water Fire Earth" lecture during my bachelor's degree :D

At least, metereology and climate science belong squarely into the fold of physics at our university, as far as I know

@Sanya Well, that's the thing: we are already being flooded by questions about history, enough that the debate about which of them are on topic and which are not does need to be settled.

@DavidZ ok, sorry for interrupting then

@Secret (We are not sure scientifically if something that play similar roles exists in the concept of spacetime (because it is a static structure))

@DavidZ "flooded"? really? question that. aka ACM [citation needed]

5:24 PM
@ACuriousMind those were squarely excluded from physics everywhere I've studied. They use physics, of course, and there are physics professors who do research which is very relevant for meteorologists, but that itself does not necessarily make meteorology part of physics.

@ACuriousMind re that, noticed awhile ago near-celebrity Hansen has mostly physics bkg... think hed make awesome guest spkr

@Sanya Well...I think the point of off-topic policies and setting the scope clearly is that otherwise the scope tends to drift. Waiting until the decision on scope is urgently needed (possibly because allowing questions has led to a flood of them) is not really a good idea

@vzn yes, flooded in the sense of having enough of these questions that the process of handling them becomes repetitive and is damaged by inconsistencies

Additionally, unclear scope tends to lead to tedious arguments in comments and on meta about whether or not a certain question should have been closed - which can be avoided if a sharply defined general policy is in place. And everything that minimizes drama on meta is a good thing in my book

@DavidZ SE is awash in inconsistencies, its unavoidable with thousands of questions across sites incl this one (leaving wild MSO out of picture), think the meta post is great/ sufficient effort so far

5:29 PM
what about David's earlier criterion of whether you'd need to actually go into historical sources to answer the question or even give a reasonable hypothesis? Historical sources being everything not published scientifically

-1

Is there a flag for flagging as insufficient research effort? Or do I need to use a custom reason flag? (Should I even flag a question as such? I know a lot of people do...) Sorry if this is a dumb question.

@DavidZ We have a dedicated institute for "environmental physics", which includes (significant parts of) meterology/climate science. I wasn't aware that's an unusual state of affairs

think this has all been mostly worthwhile but notice that mods/ high rep users tend to focus/ fixate on technicalities/ hypotheticalities sometimes etc aka sometimes called "analysis paralysis" in CS

@ACuriousMind well, Heidelberg is "special" in a certain sense. Normal german universities won't have funding for that :D

Ah, the blessing of "excellency" :P

5:33 PM
@ACuriousMind Sure, I'm not challenging the existence of environmental physics as a (sub)field. I'm just saying that, as far as I know, meteorology and climatology are usually considered separate fields in their own right, not sub-disciplines of environmental physics or of physics.

Well...then I must say that don't feel qualified to decide which parts of meterology are environmental physics and which aren't

I'm not qualified to draw that line either, but there are some things that are far enough on the meteorology side that I feel comfortable saying they are (or, should be) off topic for us, and that's one of them.

@ACuriousMind you're needed in the math chat

@0celo7 what for?

no hes not
>_>

5:41 PM
@ACuriousMind explaining a physicist proof to young Obliv
the mathematicians are nervous

5:51 PM
@Secret That's really cool. have you always been interested in art or is this something new for you

Man, Mathematica sometimes does some things....
> Simplify::ztest1: "Unable to decide whether numeric quantity -180°+π is equal to zero. Assuming it is."

XD Mathematica <3

1 hour later…
7:26 PM
@JohnRennie hello

8:04 PM
so, @0celo7, have you come to terms with C?

8:15 PM
@yuggib was wondering what you meant by this. can you recommend your favorite ref/ survey on it?
Jul 12 at 16:32, by yuggib
@MAFIA36790 It would be nice, but also very time consuming. I think I have a good expertise on some topic where a nice overview is missing (the classical limit of quantum theories of course)

@vzn there is no ref/survey on that

@yuggib had feeling/ thought you might say that

apart from books treating semiclassical analysis from a purely mathematical point of view, and that limit themselves to quantum mechanical systems (no QFT)
and the language is very far from physics

anyway have looked into that area/ boundary myself somewhat, think its very meaningful

indeed it is, and I think that most people don't know what is the state of the art in the topic

8:34 PM
Does anyone actually understand what this question is asking?
I'm unable to send it into the review queue since I dupe-hammered it and then reopened it.

I have kind of an interpretation, can
't guarantee you anything though
when I learned classical mechanics, electrodynamics or QM, I knew that if I had this and this system, I would need to solve this and this set of equations to get the time evolution and have the whole system described; now, I've only had introductory lectures to QFT but I've often found myself searching for a parallel to that during these lectures - maybe that's what OP means?

But OP claims they know the quantization method of QFT, so they should know that we have a Hamiltonian just like in ordinary QM
It's just that you can't extract much information from directly applying the Hamiltonian

hmm, while I read the question, I was more thinking "he probably has no clue what QFT really is", but maybe that was my mis-interpretation
his first version said "Assume an understanding of Hamiltonian mechanics, electromagnetism, non-relativistic quantum mechanics, exterior calculus, gravity, and abstract algebra (including Clifford and Lie algebras)."
I found it remarkable that QFT was not in the list

@Sanya Well, I thought that too - that's why I initially closed it as a duplicate of "How is quantizing a field different than quantizing a particle", but they kept insisting that their question is very different and they know the difference in quantization, so I reopened it, since I don't want to abuse the gold badge to close things that aren't duplicates. Alas, now I can't cast the unclear what you're asking vote that the question actually deserves... :P
The two answers make me think the answerers don't really understand the question, either

well, the first just described a part of QFT in my understanding, namely path integral formalism; but in a way they are just giving the parallel to the "programme of solving Schrödinger's equation in QM"
the other answer escapes my understanding

8:48 PM
It's talking about defining QFT as the limit of a lattice theory (many-variable QM, essentially), instead of as the quantization of a classical field theory. How it is supposed to answer the question I don't understand either, but then, I don't understand the question to begin with

ah ok, lattice QFT rings a bell, but I didn't get that from the answer
well, I'm curious to see what OP thinks of the path integral answer
another question - someone on physics SE these days claimed that gauss' law (i.e., the first of Maxwell's equations) was only valid for electrical fields vanishing at infinity. I've been trying to see the reason for that, but I've really not come to any useful idea - anyone got an idea?

@Sanya If the field is not compactly supported, you get an issue with the equivalence of the integral and differential forms of Gauß' law, since the divergence theorem that is responsible for that equivalence only works well for functions with compact support.

ah, now I see what I've missed - I read about compact support and thought "well, I only want to use it on a compact volume, what do I care about infinities"
but I guess globally speaking that makes sense - thank you
(not that it would make any sense physically to have a field at infinity)

9:06 PM
There's plenty of rigorous QFTs
they have their problems but what theory doesn't

@Slereah The OP isn't looking for "rigorous QFT", I linked the Wightman axioms and they said they knew them but they aren't what they're looking for

What is he looking for then?
Also what post

Uhhh...why did you start talking about rigorous QFT if it was unrelated to the post I linked?

I saw the conversation but not the post :p

Ah
34 mins ago, by ACuriousMind
Does anyone actually understand what this question is asking?

9:09 PM
Ah yes
Wouldn't it just be to find the evolution of the wavefunction as well
One thing I'm still not quite sure about QFT is the relation between the observables and real laboratory measurements
Like what's the best method to model an apparatus measurement in QFT
I'm guessing something like $\hat O [g]$, with some measurement $\hat O$ over a test function $g$, where the support of $g$ is roughly the extent of the measuring apparatus?

Hey folks
can someone running windows or OS X tell me what they get there ↑
should be an interactive gathingammy

9:25 PM
I get a sluggishly reacting thingy that shows some sort of colored field lines

@ACuriousMind Excellent
And it responds?

@EmilioPisanty Well, it takes between 5 and 10 seconds after I adjust the value to show the new image, but yes, it responds

@ACuriousMind Yeah, that's probably about the best one can hope for
Here it is for context in all its glory
10

For a system of electric charges $q_i$, at positions $\mathbf{r}_i$, with a nonzero net charge $Q=\sum_i q_i$, one can define a "centre of charge" in the obvious way as $$\mathbf{r}_c=\frac{1}{Q}\sum_i q_i\mathbf{r}_i.$$ This concept is definitely not as useful as one might naively hope, but it...

Finally cracked it

@DavidZ I concur about the usual grouping of climate science and meteorology and climatology as their own topics, but the preparation for them is basically a physics preparation.

@dmckee Hi! I want to ask you a question, but I am afraid of you get uncomfortable or take personally.

9:31 PM
When even hired a meteorology MS as an adjunct physics professor for a couple of terms until he went back for his Ph.D. Good egg.
@lucas How 'bout I promise I won't take it personally but wont necessarily answer?

@dmckee Don't you think that this should be a comment not an answer?
18

Energy (in any form) falling into a black hole contributes to the mass of the hole, and mass is one of the many forms that energy can take, using the usual conversion factor: $E = mc^2$.

So that's an interesting question.

Well Schwartzschild is time syhmmetric

The design purpose of comments was to help improve questions, and the idea was that they would only be used that way.
In practice they've been used to make jokes, puns, almost-but-not-quite-an-answer pointer to other resource and other random remarks as well.
And on a few sites—including physics—there has developed a habit of providing terse answers to questions that might be closed as comments.

9:35 PM
That's not really how the site was envisioned working, and I have recently become convinced that it is not that great for the site.

So I've started trying to discipline myself to not do it. If I want to write a pseudoanswer, I post it as an answer.
@lucas It is certainly a very short and minimal answer. I'm with @EmilioPisanty that it does answer the question or I wouldn't have posted it. I did not, however, expect that kind of reaction to it. Probably the best thing is for me to expand on it a bit, but I have summer-term final exams looming and don't have time for the research until at least next week.

@EmilioPisanty I agree with you. But some short answers like it, have been deleted before as low quality posts.

I think it is currently far overvalued.
I blame that on the Hot Network Questions sidebar (curse it).

Thanks for reply! I hope you didn't get uncomfortable. @dmckee

9:41 PM
@dmckee I'll allow you to complain about overvalued answers when you get a gold badge for stating the result of an elementary SR exercise :P

@lucas Examples? I'd say "this doesn't happen" because I don't see it much, but it may yet be true.

@EmilioPisanty I suspect t does happen, but I don't think it is terribly common. Probably happens most when there is disagreement on how far an answer has to go to be an answer.

@dmckee Yeah, I guess. The top of the LQP recent deletions is stuff that's not really an answer.

@EmilioPisanty You always want me to give evidence. But I don't want to claim in a court! It was a friendly question :-)

@lucas Bear in mind that when we ask for examples it's never "provide evidence or we will cease consideration of what you're saying". It's "if you provide examples it will be much easier to know what you're talking about".
In this particular case, when I review on LQP I never VTD anything that actually answers the question, or provides a decent attempt at it.

9:45 PM
@ChrisWhite Back when the network was much smaller this was not only considered but actually <status-planned> for a while before suddenly being replaced with changes to voting on questions.

But then I can't speak for others' reviewing habits.

We could bring it up again, but we'd want to have our ducks in a row first.

@dmckee hah. markdown says no-no to your recursion games.

Damn you, MarkDown! I'll get you for this! You and your little goto, too!

@yuggib :

9:49 PM
@EmilioPisanty I am sure about you! You are so nice and I can trust you with closed eyes. Believe me ;-)

in Mathematics, 3 hours ago, by 0celo7
The problem with physics is that you never know how much bullshit is too much
I think those are wise words :P

@dmckee and also @ChrisWhite I've been saying this for ages. This is a Bad Thing.
I also ran it against a few other sites the other day, our top users are quite a bit higher up than in other sites.
I don't have the SQL-fu to port it into a cross-site query, though.

@EmilioPisanty You posted that a week or so ago, didn't you. It is pretty bad.
Our discipline does, after all, attract a lot of would-bes, and the scoring structure of Stack Exchange rewards persistence even for users who are way off base in some aspects of the field if they will merely write a few uncontroversial posts as well.

@dmckee Yeah, I've posted it here a few times.
It bugs me that when people say "hey, what's with the five-to-one upvote-to-downvote ratio?" the standard response is "well, they'll just give up and won't get much rep anyway, so it's not a problem".
That's maybe true in other sites, but here we've got a pretty strong showing of 1k+ users that can and do say some really off-base stuff, and they get to have this nice juicy Community Trust number to their name
Next thing we know we'll have a 10k user on that list, and I'm afraid that that will cause a fair amount of damage.

10:06 PM
@EmilioPisanty I think he/she is one of the bests of PSE.

@EmilioPisanty I think this line of thinking is part of an argument for giving us a variation in scoring rules (at least on a trial basis). Or giving us some additional tools for tells such users to take a hike.
We don't have a suspension reason for posting consistently bad answers, even though there is one for posting consistently bad questions.

@dmckee Yeah, but that's some pretty strong stuff, though.

@dmckee Wait...we got to the downvotes because we were worried that deleting wrong answers might be a bit heavy-handed, and now you're suggesting getting rid of the users responsible for the wrong answers altogether?

@EmilioPisanty Yeah. It's a big ask from the team and we're going to have to know why it's a good idea before we bring it up.

@dmckee I don't think mod-mediated suspension is the way to go. Pretty much a non-starter. Remember all the stuff with the person when the thing?
Double the trouble.

10:09 PM
@ACuriousMind More like exploring options, just now.

@dmckee On the other hand, I think we can make a fair argument that we get enough actively-bad posts from persistent users that we do need bitier downvotes

It's the usual brainstorming thing: even the stupid suggestions are valid during the "what idea do we have phase". Then you kill them with fire if they deserve it.

@dmckee Yeah, that's a kill-it-with-fire-in-a-way-that's-friendly-to-the-poster sort of idea ;-)

@EmilioPisanty I was strongly i favor of bitier downvotes, way back when. But the team was very reluctant.

@dmckee Yeah, but then engine changes across the network need to work for a huge number of different situations

10:11 PM
@EmilioPisanty 'K.

Well...I can understand their reluctance, look how many "make explaining downvotes mandatory" or "don't let people downvote my awesome posts" meta.SE already gets now, where the downvote is rather ineffectual in terms of actual rep. Imagine how much worse that would get.

The community moderation workings in The Workplace vs Stack Overflow vs English Language and Usage vs etc is a very varied landscape, and you can sort of guarantee that a change like that will really impact at least, say 5% of the network sites
so that's like seven sites getting thrown under the bus
@dmckee Thing is, it depends (in the end) on a single person taking a moderation action based on a technical assessment of the quality of a person's content.
(As in, the content they produce. Not what's physically inside them.)

They have discussed the possibility of parameterizing some parts of the engine in the past. Always in terms of "this is technically possible, but would be a big effort and therefore needs a big justification", but I don't think it is completely off the table to have heavier downvotes on Physics than Cooking.

That's the same reason David is so adamant never to have technical flags on the mod queue

Though, of course, anyone giving bad advice on cooking should be forced to eat the results.
3

10:15 PM
At least the question upvote rep value is adjustable, stackapps has +10 for questions.

@dmckee No, I think we've got a good chance of showing numbers that say there's something not working for us
@ACuriousMind Isn't stackapps a slightly different site, though? Or is it otherwise the exact same engine?

Which bring the question to "How would we want the scoring changed?"

@dmckee Yeah, that feels like a thing
But also you've got to consider what it would do across the board.

@EmilioPisanty They use a lot of common code, at least.

@EmilioPisanty At least their question tab and the questions themselves look the same to me, but of course I can't look under the hood
@dmckee Anyone given bad advice should be forced to eat the results?

10:17 PM
Just changing the downvote to -3 would adjust the cancellation ratio from 5:1 to 3.3:1.

What happens to a well-intentioned newbie when s/he sees this small mound of rep they've worked pretty hard for get really blown away because of some mistake?

@ACuriousMind Ouch. They already are, I think.
I think faster than I type. And you guys are so fast I rush.
I have this thing where I can't type "ratio" without getting "ration".

@dmckee Yeah, there's something to that.
@dmckee the o and the n are like miles away from each other

It's still a pretty big overall change to the site. There are many thousands of downvotes out there.

@dmckee Yeah. Way too many to really gauge the impact, I think.

10:19 PM
@EmilioPisanty It seems to be some tic of muscle memory.

@dmckee Were you under strict rationing at some point in your life?
Plus, what happens with all the old votes? Do a bunch of people's reps get these huge changes in the several hundreds, losing privileges and all? I mean, that's sort of the point, but for sure they won't be happy.

Man. I looked at this to see how many downvotes there might be. I've surpassed the community bot in downvotes. :/

@EmilioPisanty That's what happened with the change of the question vote value. There was a fuss about it, too.

Good god

@ACuriousMind I keep telling my self I have so many because the stupid flags make me look at a like of the worst posts on the site. I still feel a bit bad about it, but not much.

10:27 PM
@dmckee I see the accepted answer took the concerns seriously and elaborately addressed them...

And another fuss when the old periodic rep-recalc mechanism had gotten way behind and they fixed it, applying the fix to everyone in the course of a few days. Some folks too a big hit.

ACM is just a meanie :/
@yuggib Perhaps.
The thing about the set of double sets really shook me to my core.

@ACuriousMind That's a scary query
↑ completely unintentional rhyme
OK, maybe 50% intentional
@0celo7 What, the countable disjoint union of $\{0,1\}$s being uncountable out of AoC? Yeah, that was pretty bad.

Yup
But well-ordering might be worse.
So the issue is not resolved.

How could something called well-ordering be bad? :)

10:40 PM
How could something called well-done be the Satan of meats?

@EmilioPisanty it is?
@0celo7 ..."the Satan of meats"?

what is unclear

I'm not sure what that means

Anyways, I need to bounce, but I do want to plug this answer one more time 'cos I'm pretty proud of it
10

For a system of electric charges $q_i$, at positions $\mathbf{r}_i$, with a nonzero net charge $Q=\sum_i q_i$, one can define a "centre of charge" in the obvious way as $$\mathbf{r}_c=\frac{1}{Q}\sum_i q_i\mathbf{r}_i.$$ This concept is definitely not as useful as one might naively hope, but it...

Is there a Satan of vegetables, too?

10:41 PM
Yes, sauerkraut.
@ACuriousMind I'm dissecting a Milnor proof, you might want to run.

11:20 PM
you're a sour kraut

that's not what your mom said last night

11:39 PM
@Slereah want to help with Morse theory?
son :)

@0celo7 $\cdot \cdot \cdot - - - \cdot \cdot \cdot$
Does this help

no
and you're a troll :/
Not what I want from my step son

Don't talk to me or my son ever again