The h Bar - 2015-08-04 (page 1 of 2)

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12:00 AM

@0celo7 dude

you better learn to deal with SJWs now

it's only going to get worse as you go along

Jesus I can't even imagine how crazy the SJWs will be when you're a senior in college

user54412

Take line 265 in your code for instance. You might add another command after MonteCarloStep... that's part of the loop. Then you'd need the innermost braces, but you might forget to put them in.

user54412

Same thing if you add a command outside the y-loop but inside t and x

user54412

A good text editor would give you a hint of something wrong when you tried to type this in, since it would put your cursor at the wrong indentation. But if copying and pasting you have to be aware of your surroundings.

user54412

To be honest, of the many, many classes of bugs I've written, I've never made a mistake in this regard.

I see. Writing it without the braces feels somehow...unfinished to me, though :D

12:07 AM

ACM is a pedant

user54412

I never liked unneeded braces. And then I discovered the magical syntax of Python.

You just have to indent the stuff right, right?

I remember liking Python, but I never wrote something longer than a few dozen lines in it, I think

@0celo7 Truly a new revelation.

@ACuriousMind: In the comments under my answer to [this question](http://physics.stackexchange.com/questions/138217/complex-integration-by-shifting-the-contour) you made some statements about the Feynman prescription. In particular, you said that it corresponds to propagating some modes forward and others backward.
What question could I ask, or what bribe can I offer you to develop those thoughts into a full self Q&A on the site?

@ACuriousMind Explain to me again why I can't multiply through by $\mathrm{d}x$ and then integrate?

@ACuriousMind Python's excellent until your project gets really big.

It's probably the best choice for "casual" scientific use. See also Julia, however.

12:21 AM

Pfft, everyone knows that the casual scientific language is IDL

@FenderLesPaul You doing anything? Wanna brainstorm 8.1.1

@KyleKanos As I said long ago in this very chat, IDL should be ostracized.

@DanielSank Well, reminding me of that was already the essential step ;) I think I can do that quite easily, the discussion of that should be somewhere in my QFT stuff.

@DanielSank No way...it needs to be set on fire

^ Truth

12:23 AM

@KyleKanos Oh god, this abomination cost me one week of my life when we had to deal with it in an astronomy lab

user54412

@ACuriousMind I'm wondering what SU2Mat actually is. A 4-vector? A 2x2 matrix?

@ACuriousMind Consider yourself lucky. I know some people who are learning it for their careers because their advisor handed them a piece of code in it

@ChrisWhite It's a vector with four entries encoding an SU(2) matrix, since every SU(2) matrix can be written as $U = u^0\mathbf{1} + u^i \sigma_i$ ($\sigma_i$ Pauli matrices, or perhaps half of them, depending on your preferred convention) The thing encoded in SU2Mat is the coefficient vector $u$.

user54412

Ahh

@KyleKanos Ugh, that's a terrible way to begin a career

12:27 AM

@ACuriousMind I tried convincing them they'd be better off learning Python to do their processing, but, for whatever reason, they insisted that I was wrong

@ACuriousMind Those sweet moments when you say something intelligible

if anyone cares, I'm testing Metro 2033 streaming twitch.tv/revolver_0celo7 (note: I'm utterly shit at this game, it's probably funny to watch)

12:51 AM

who was my one fan?

1 hour later…

1:57 AM

@0celo7 wanna brainstorm it tomorrow evening?

I have a few calculations to do

@FenderLesPaul sure

sweet

I can only play Metro in bursts...the stealth sections are crazy hard.

My silenced gun is a BB gun

2:44 AM

@ACuriousMind are you attempting to replicate a paper or book result? maybe consider opening chat room for the prj/ discussion. missed the setup, its all spread out in transcript

@dmckee thx again for posting this! any opinion/ reaction?

re ACs effort, in case anyone hasnt heard:

220

Proposed Q&A site for the "open science" movement to make scientific research, data and dissemination accessible to all.

Currently in commitment.

@vzn Well, not exactly. It's a project for a course, and the task is pretty much "Simulate an SU(2) gauge theory in 4D with Monte-Carlo heatbath update and measure the Polyakov loop for varying lattice sizes". There are loads of papers (mostly from the 80s) on this subject, and they all do slightly different stuff. So I'm "essentially" replicating things that have been done, but, well, the primary goal was that I produce a working simulation myself, not the replication as such.

3:06 AM

@ACuriousMind Great. Looking forward to it. Do ping me when you write it. I'd hate to miss it.

@KyleKanos Give me their email. I'll try to save them. It's abusive for an adviser to let his/her students learn IDL instead of python just because that adviser knows IDL already.

@ACuriousMind Impressive bed time

@ACuriousMind So that fps alt tab thing is still there...but it's been there for a while.

@DanielSank Dude I've tried everything: cost, syntax, ease, collaboration, no black boxes, and so on. They're basically frelled

@KyleKanos Egad it hurts.

I was playing with GTA 5 gfx settings, like increased reflections, shader quality and grass.

20fps

@DanielSank I can't shake the feeling that I also promised you another answer this way once. Did I ever deliver it?

3:09 AM

@KyleKanos What you call "collaboration" is the real reason I think it's not ok for an adviser to go for IDL.

So I alt tabbed because I wanted to make a list of things I'd tried. I go back in the game and it runs perfectly at 30fps

Learning python is getting to the point of being like learning English in science.

@ACuriousMind Heheh, I don't remember.

Now I tried these exact settings back when I bought the game and I got those 20fps

@ACuriousMind You exceeded my brain's statute of limitations.

Does anyone know why alt + tab increases my fps? Is that like a gaming SE question?

3:11 AM

@0celo7 Well it's hardly a physics question.

@DanielSank Heh, not sure whether to be relieved about that, or annoyed that now don't know either what it was

@0celo7 I vote that comment off-topic.

@DanielSank Well would it be acceptable for gaming SE

Obviously not PSE

@0celo7 I have zero clue.

Ask their chat?

I'll try tomorrow

It's very strange.

3:12 AM

@0celo7 "Bed time" is a concept I have transcended.

@DanielSank I concur. It's syntax, for the most part, is pretty straight-forward

Only when you start jumping into classes does it get slightly more complicated

@ACuriousMind Funny thing. I'm going to bed now.

That's not very funny :P

@KyleKanos I actually think the python object model is remarkably self-consistent.

'cuz you know, literally everything is an object.

Even classes.

@ACuriousMind Can vampires feel humor?

3:14 AM

:D

Omg are all Germans vampires?

night

@ACuriousMind It just hit me: what if I was having this same issue when I tried playing Witcher 3...shit

Oh I'm not gonna get that out of my head

@ACuriousMind ok. did you post a link to the code earlier? others seem to be able to find it. :( ... creating a working simulation is essentially the same as replication. not sure what distinction you are making there.

3:29 AM

@vzn The code is here. The distinction I'm making is that I'm not replicating any specific study, just the general method (since the specific studies often have added complications like renormalizing the observable, or having unequal temporal and spatial slicing, or other things)

@ACuriousMind ok, yet probably the "general method" is also published somewhere.

The fact that I'm not exactly reproducing any of these studies also makes me think that it is possible that my lecturer is wrong in claiming I should see a non-zero value. But still probably more likely that I'm doing something wrong.

my idea/ strategy would be to try to find a published result closest to what is to be built. or start by replicating some simpler, "baseline" result.

are others in the class? maybe get a study group going on it?

@vzn Yeah, but the general method paper (That'd probably be Kennedy/Pendleton on the heat bath algorithm in this case) doesn't present any testing - they just abstractly show it works, so this indicates nothing about my specific case.

@vzn Hah, the class is three students, and they picked projects different from mine

@ACuriousMind I am amused that I don't understand the titles of any of the questions you've asked on the site.

3:35 AM

ok maybe there is a way to do a "sanity check" on simpler results that would be expected. also, checking with the prof for ideas is surely ok.

@vzn I'm already doing that - all sanity checks (as in: check the functions are doing what they are supposed to do) I can think of succeed, and the prof also doesn't have any specific ideas what the issue may be

@DanielSank That's probably also why almost no one looks at them :/ (Also, my first two are rather weirdly posed, but, well, they were my first)

@ACuriousMind another thing I just noticed: questions asked by folks who frequent the chat tend to be favorited a lot.

You're five for five.

@ChrisWhite is four for four.
I'm 70% of my 13 questions.

user54412

My question scores have only gotten worse as time goes on.

@ChrisWhite but interestingly the frequent chat users post questions which tend to get favorited.

It's probably because we're asking questions which don't have easy-to-find answers elsewhere.

Well, favouriting is not clear on what it means: Qmechanic certainly doesn't like every one of his 3,693 favourites (or even finds them interesting), and I know I have favourited some questions rather for the WTF factor than because I like them.

(although those are now mainly deleted)

3:48 AM

Woah, Qmechanic does have a lot of favorites. Weird.

@ChrisWhite There's a strong correlation between catchiness of title and score there

user54412

I only ever favorite posts in meta I think.

user54412

@ACuriousMind :P

LOL Qmechanic has over a thousand answers and zero questions.

@Manishearth Qmechanic has zero questions because Qmechanic knows everything. This is common knowledge... — twistor59 Jul 16 '13 at 18:09

Oooh, I'm exactly at 500 answers and 5 questions. I need to stop participating.

3:51 AM

@ACuriousMind how did you link old comment?

permalink?

@DanielSank Click on the time-stamp, the URL you get links directly to the comment.

Wat?

I think I haven't understood your question

@ACuriousMind I figured it out. You click on the left side of the message box and then click on 'permalink'.

That's probably what you meant >.<

Ah, that's for chat messages. But I linked a comment there...I'm confused now

3:54 AM

Ciao, everybody.

@ACuriousMind Oh, it was from a comment? Ok, now I get it. Thanks!

@DanielSank Ciao

2 hours later…

5:45 AM

@KyleKanos nice answer to the milky way quasar question

6:02 AM

I think this is a bad question but I don't know on what grounds to close it.

2 hours later…

7:54 AM

mornin

2 hours later…

9:40 AM

My favorite cosmologist is Starikov because he has star in his name

It's a handy way to remember him

3 hours later…

12:39 PM

@DanielSank Close it as a homework question with little or no effort ?

Also, how did Community protect the question ?

@Gaurav When a question has many deleted answers, Community can decide to protect it.

In this case, there are four deleted answers there you can't see.

@ACuriousMind But Community isn't a person isn't it ? Must be an algorithm or something that triggers it to protect ?

@Gaurav Yes, there's some algorithm that protects questions that "received too many crappy answers" (I'm not sure what the exact criteria are).

1:02 PM

@Slereah Seriously? You missed Starobinsky?

> ...the electron is fundamental particle of light...

user image

user image

Hi KK

Hi Danu

Leaving it as D looked weird

Like it was a half-smile or something

Some people call me "Big D"

Due to your inflated ego? :D

1:05 PM

Danu : Oh right, I actually mean Starobinsky

3 mins ago, by Danu

user image

@KyleKanos ...right ;)

I confused him with a dude I know named Starikov

Okay, maybe not so bad :P

Planck should have been a wood scientist

xylologist

Am I wrong thinking that this question on Continuum hydrogen emissions is a little misguided? OP want s a quantum treatment of the continuum, which is really the Planck function, no?

1:20 PM

@KyleKanos I don't think this is about the thermal spectrum. Wiki says: "The classical example of a continuous spectrum, from which the name is derived, is the part of the spectrum of the light emitted by excited atoms of hydrogen that is due to free electrons becoming bound to a hydrogen ion and emitting photons, which are smoothly spread over a wide range of wavelengths; in contrast to the discrete lines due to electrons falling from some bound quantum state to a state of lower energy."

Hmm, the thermal component is due to collisions & OP does say Hydrogen atom.

Also, the comment reply to the guy saying QM books should treat that indicates that this is really about the continuous spectrum of the Hamiltonian in this case, i.e. scattering states.

@KyleKanos Hah, that article you linked has "Hulburt" as second author. Sounds like someone failing to say "Hilbert"

Hilbert is an anagram for Hitler B

I'm not sure what OP actually wants for that, now that I read it again - what's a "spectrum decomposition", exactly?

1:22 PM

Part of Spectral Theorem, I presume

@KyleKanos Well, the decomposition is well known - there's a bunch of discrete bound states, and a lot of continuous non-normalizable free "states" (which correspond to the continuous spectrum). Still not sure what OP wants.

I commented pointing OP to a discussion of scattering states, perhaps that's what they want.

1:51 PM

Historically, did conjugation (in the group theoretical sense) come up/first attract interest because of changes of bases in linear algebra, or is there another motivation?

@Danu No idea what came first historically, but a totally different motivation is that the representation theory of finite groups is completely controlled by giving functions on the conjugation classes. Yet another way it shows up: Normal subgroups (the ones you can quotient out) are precisely those invariant under conjugation.

@NeuroFuzzy Thanks. I also just updated it to cover the missing papers I didn't want to spend time researching for last night

2:13 PM

@Danu: I am not sure about this but I believe the ideas of vector spaces, spanning sets, basis, dimension and basis transformation only occured by the end of the 19th century (Grassmann, Doctrine of Linear Extension). I only know very basic abstract algebra, but I recall most results from abstract algebra emerging in the 18th century and beginning of the 19th century already (Lagrange, Cauchy, Galois) so I'd suspect it to develop in the context of abstract algebra first, or simultaneously.

181

Q: How do we encourage edits to obsolete/out of date answers?

As the network ages and we have answers that are 7+ years old, we run into situations where changes in technology, etc. result in a once great answer becoming out-of-date, obsolete, or somewhat problematic. We don’t want to lose or delete these answers, due to legacy applications that still need...

discussion featured edits suggested-edits answers

Top-rated answer there suggests a Vote as Obsolete queue and says,

> This could also work well in sites as big as math.SE, or even physics. But, Newer sites, and the ones with less traffic won't really need it IMO. Those posts could simply bump into the VLQ queue, with new options: "Looks OK" and "mark as obsolete".

Have we run into such an issue that an answer is obsolete?

@Danu: So the historically original intention could also have been the study of center and normal subgroups?

@KyleKanos Don't you need to have current expertise in the subject to "mark as obsolete"?

@KyleKanos How the heck would a math.SE answer become obsolete?

@KyleKanos Like you probably wouldn't know if some answer about a string theory model was out of date.

2:18 PM

@0celo7 A discussion point in the post. He recommends something like 30k rep

And it is very unlikely that a physics answer will become obsolete, since we deal in accepted mainstream physics, after all.

@ACuriousMind IDK

@ACuriousMind No.

Sometimes mainstream theories get changed a lot.

@ACuriousMind True, but what if String Theory is wrong, then we've got 1000 questions to go through and mark as obsolete :D

Or what it neutrinos are massless

@Danu: Looking at the dates it must have been Galois who first introduced conjugation, for he needed normal subgroups to get automorphisms of subfields.

2:20 PM

@KyleKanos Well, we could also migrate them all to hsm.SE :D

What if the speed of light varies? Or does not vary? Or whatever the hell Duffield thinks it does.

(not sure if you have already progressed to this point in abstract algebra, @Danu)

@ACuriousMind That sweet moment when QFT is hsm material...

This could also work well in sites as big as math.SE, or even physics. But, Newer sites, and the ones with less traffic won't really need it IMO. – I do not see anything wrong with a review queue that is hardly ever used. On some sites, getting a Reviewer badge for late answers is near impossible. Also note that Math is bigger than SU and SF right now (but then answers rarely, if ever, become obsolete there). — Wrzlprmft Aug 1 at 11:15

So someone's already pointed out math.se as a bad example here

I really don't think we have any problem with "obsolete answers as the technology progresses". This meta discussion simply does not concern us, imo - we won't use any of the things they may implement.

2:27 PM

@ACuriousMind So Weinberg's GR book that says neutrinos travel on null geodesics is not outdated in some sense?

I concur, but I was tossing it out there for the case that there was an obsolete answer that was accepted

Or when he says black holes probably don't exist because there's no evidence at all.

@0celo7 Oh it is. And how many answers can you find on this site that are outdated in this sense?

@ACuriousMind Not many because the site is still "young".

Just because it doesn't affect us now doesn't mean we shouldn't get the capability for the future.

Hm, this opens up a bunch of related issues - do we reopen questions closed as "non-mainstream" when their content has become mainstream enough?

2:32 PM

@ACuriousMind Good point.

@Huy I know what all of those words mean... but I'm not sure about the combination ;)

@Danu: Did you do any Galois theory yet?

But I can now see that in questions where the answers have to rely on "to the best of our experimental knowledge", the answers might indeed become obsolete unexpectedly.

@ACuriousMind I'm thinking we'll soon have to revise all answers mentioning confinement :)

@Huy Nah, it's only the last chapter of my book.

2:38 PM

@Danu: Then you'll make more of the combination of the words by then. :)

@ACuriousMind I do not believe there's been precedence, but if it were to happen and OP edited appropriately (e.g., adding link to published works), I should think that we should reopen it

It's going to be a great chapter!

@0celo7 :P

2:50 PM

@ACuriousMind So how does the Jüliger model explain why there are no free quarks?

@0celo7 What is there to explain? Evaluating the expectation value "correctly", one simply sees that the order parameter stays zero, and the deconfining phase is never reached. :P

@ACuriousMind Oh, they never deconfine?

@0celo7 Yep, vanishing Polyakov loop is the confining phase

I wonder what happens if you do like

The evolution of a single solitary quark

@Slereah Can't put a single quark on a lattice, cf. "fermion doubling"

3:05 PM

But what about just

Single particle state

Without any lattice model

...that's real time evolution of a non-thermal state, you need to use non-equilibrium QFT for that, I think

But it should be possible, again only numerically in most cases

Especially for QCD

QCD is godawful

anything Q is godawful

Free fields are pretty simple

full of contradictions, cf. the Jüliger model

3:09 PM

And I think the numerical solution would have to deal with the fermion doubling again

3:31 PM

I hate HNQs

HNQ?

not network question

i.e. ACM doesn't like what other people like

@ACuriousMind yeah, they suck.

Also, I find it hilarious how you've started to manually put in sectioning in our chat transcript

@Slereah

stackexchange.com/questions?tab=hot

oh

3:36 PM

@ACuriousMind Which question is bothering you? Or is it you being distracted by them?

-1

Q: What is a simple expression of the homogeneous inflationary metric

The Inflationary period in the history of the universe is a time of homogeneous, exponential expansion. What is a simple metric that expresses this period?

general-relativity cosmological-inflation

so lazy?!

3:48 PM

I love how the Wikipedia page for the Keldysh formalism is pretty much just placeholders. Someone got lazy.

At least some of the links are okay starting points.

@HDE226868 I have good references for it. I used it in my thesis.

@Danu Really? Wow.

It's needed to do QFT in de Sitter space because you cannot do the usual equilibrium QFT

(Keldysh-Schwinger formalism)

I think some guy just created a new tag and is now kicking everything off the front page because of it

I've been reading up on it because it's used to analyze thermal radiation from bodies in nonequilibrium.

3:53 PM

@KyleKanos That'd be me :)

Oh I know

I created black-hole-thermodynamics a while ago, and @QMechanics said I should be "its guardian"... So I decided to be just that

...and that implies updating all posts that have the tag thermodynamics and mention "black holes" :P

@Danu How many do you have left?

@HDE226868 ...like 100?

physics.stackexchange.com/…

I'm at "most ideal black-body"

Of course, I have to do a quick check to see whether the correction applies every time.

What about questions that are tagged black-hole and mention "thermodynamics"?

3:56 PM

@HDE226868 That'll come later :P

also, I should specialize my search to "questions" only.

I recall Qmechanic saying once that we shouldn't flood the front page with retags

@KyleKanos Hmm :P Another good point :P

That was kinda my point with my comment above.

I never look at the "active" page, so tend to forget about that.

4

Q: Retagging and suggesting edits

Why when someone retags a question (and also when he or she suggests an edit, I think) that question becomes the first in the list of 'active' questions??? This is very inconvenient — I hate it — because it puts back questions that are really active (with new answers, for example). Retagging doe...

discussion feature-request editing retagging

4:01 PM

@KyleKanos Ah, his answer also explains why anyone would go to that tab, ever.

Well, I guess today is a day of black hole thermodynamics ^^ Sorry guys!

@FenderLesPaul see this question regarding black hole splitting -- the answers are all thermodynamic (I guess the question asks for that), nobody mentions the bifurcation theorem

@Danu I don't think I've ever used the /questions page; always the main page

@KyleKanos You should try it sometime, I like it much better (less nonsense like what I just put on the main page flying around!)

Well that's if you have it sorted by newest question.

If you go back active, then you'll see (basically) the same thing as the main page

If you sort by votes, you'll rarely see anything change

4:16 PM

@KyleKanos I know. Both suck :P

Of course, I meant "newest"

4:32 PM

But, on newest, you don't see any answers.

@KyleKanos It bothers me that I get 30 upvotes for this pithy answer.

30 upvotes

I'm disappointed that (a) someone downvoted my answer and (b) that my beautiful animation didn't attract enough votes to even by #2

@KyleKanos should I stream Oblivion

If you want.

@KyleKanos I won't stream if no one watches

4:35 PM

I'll not be available, got stuff I need to do (and keep getting distracted by PSE)

then I won't stream.

@ACuriousMind Yeah, that's BS :P

@0celo7: Do you not have a regular userbase that watches?

lol, his "userbase" are like four guys from this chat

5

:D

Awesome.

4:43 PM

@ACuriousMind screw you I'm growing

@0celo7 lol

@ACuriousMind damn that's a burn if I've ever seen one

screw whoever starred that

@0celo7 that was me :p

I'll be nicer then

4:53 PM

hehe

Effective actions in algebra?! Damn you, terminologists (I wish that there were people who get paid to think about that stuff)

@ACuriousMind I guess the entire audience starred that comment ;)

@Danu why you

@0celo7 You should know by now that such comments are counterproductive :D

It's too e.z.

Tsk

4:55 PM

@ACuriousMind only because we're infested with trolls

JD was right about that

user image

JD knows everything.

I was searching for that

I miss Sophie :(

no clue where he's from

@0celo7 Kiddo

4:56 PM

don't care, found a dwarven bow

@0celo7 Scrubs

@ACuriousMind never seen it

... you scrub

@Danu more bullying

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