The h Bar

12:00 AM

@DanielSank: The problem with modern physics are the people who don't speak our lingo. They take things that we don't mean literally... well... literally.

0celo7

@CuriousOne Like what

I am the least literal person alive

literally :D

CuriousOne

@DanielSank: Even I still talk about quanta as if they were particles... even while I know that it's wrong.

@DanielSank: But I can't help it... my electron gun is a pea shooter, not an"electrically charged fermionic quantum wave source". :-)

Physics Guy

12:51 AM

@Ocelo7 And, how do you do ?

0celo7

reading about the Euler class of an oriented sphere bundle

Physics Guy

interesting. I know what Euler classes are, but only defined on simple vector bundles.

0celo7

The construction is hairy

Working on a circle bundle for now

Physics Guy

I believe.

0celo7

What definition do you know?

Physics Guy

12:56 AM

One dimension lower-huh ? ;)

0celo7

hmm?

Sphere as in $S^n$

Physics Guy

Yeah, because you are working on $S^1$ instead of $S^2$.

I know the definition of Euler class on an n-dimensional real vector bundle.

0celo7

in terms of curvature?

Physics Guy

and the using in differential geometry for defining the Euler-class

I did not learn about curvatures of bundles yet.

Or did you not mean that ?

0celo7

well then how are you defining it?

Physics Guy

1:04 AM

Im not familiar with the PSE notation, but I am defining it as the element of the vecbundle mapped from a section of the bundle. Said in bad english.

Or, I am defining the Euler class that way.

0celo7

what

Physics Guy

the Euler class

0celo7

I have no idea what you mean by what you just said

Physics Guy

My english is bad, but I try:

Let V be an n-dimensional real vector bundle E---->X with a not negilible section s:Y ------>E on a (possibly empty) subset Y (subset of) X. Now we map an element to it e(E,s) (element of) H^n (X,Y, Z) (or e(E) (element of) H^n (X,Z) if Y is empty)

Sorry for my bad notation

0celo7

What is $H^n(X,Y,Z)$

Physics Guy

1:13 AM

I am also not sure if this definition is true.

Its in my book.

0celo7

what book

Physics Guy

German book tha I used once.

0celo7

name?

Are you German

Physics Guy

Yes

0celo7

Ich kann Deutsch wenn es mir gefällt

Physics Guy

1:15 AM

Das ist super.

0celo7

Welches buch?

Physics Guy

"Differentialgeometrie, Topologie und Physik"

0celo7

By Jost?

Physics Guy

von Mikio Nakahara

0celo7

Oh, that book exists in English too

Physics Guy

1:18 AM

Thats good.

0celo7

Actually I'm pretty sure it's an English book

I have it, what page

I'm looking, he defines it as the Pfaffian of the curvature

what are you talking about

Physics Guy

the "Pfaffian" ?

0celo7

square root of the determinant

Physics Guy

Ok, then I dont know what you are talking about. I quoted the definition from my book.

0celo7

Not Nakahara

I can't find what you said in there

Physics Guy

1:22 AM

But mine is from nakahara

0celo7

Page?

Physics Guy

239, Chapter 10 "Vector bundles, tensor bundles, spinor bundles and applications in physics"

0celo7

which edition

Physics Guy

How do I know ?

0celo7

look at the front

does it say which edition?

if not, it's probably the first

Physics Guy

1:24 AM

There is nothing :/

0celo7

one sec

Physics Guy

1989

0celo7

I can find a first edition in the library

Physics Guy

Hello, its from 1989, it stands there.

0celo7

what?

I got a first edition

Physics Guy

1:27 AM

And ? 1989 ?

0celo7

page 239 is about killing vectors

and chapter 10 is 100 pages later

and titled differently.

Physics Guy

Are you sure, we are talking about the same book ?

0celo7

Geometry, Topology and Physics by Nakahara

Physics Guy

:/

Yeah.

0celo7

can you give a link to the German version?

Physics Guy

1:29 AM

I dunno where to find.

peterh

2:12 AM

@0celo7 Du bist Muttersprachler?

0celo7

Bin dort geboren und aufgewachsen, aber bin Ami

peterh

@0celo7 Wow! What a high level club is it. :-)

0celo7

Was meinst du

peterh

@0celo7 Was für eine exotische Community haben wir hier im PSE :-)

0celo7

Indeed

peterh

2:20 AM

@CuriousOne As I know, string theory requires a quite high level math, how can they do this without super-excellent math skills?

@0celo7 A "League of extraordinary gentlemen" :-)

0celo7

2:32 AM

@peterh Hand waving

vzn

@CuriousOne exactly; who said it?

Yashas Samaga

3:34 AM

The Real Meaning of E=mc² | Space Time | PBS Digital Studios

►

do we really consider the KE of electrons while solving nuclear physics problems? -,-

nvm

DanielSank

4:16 AM

I'm surprised this never got a good answer

0

Q: Can special relativity be extended such that the frame of a photon makes sense?

Suppose I want to know what the universe looks like from the perspective of a frame of reference moving at $c$ relative to my current frame. As discussed at length in various other questions on this forum, from the perspective of the current established theory of special relativity, the notion of...

Everyone went off assuming I was asking something other than what I was asking, and making weird statements about how I should get a new "research project".

John Rennie

Hi Daniel. Is "raise eyebrows" such an obscure phrase?

DanielSank

@JohnRennie Well, I raise my eyebrows when I'm skeptical or surprised.

I don't think it is correct to say that we wish to exclude any answers which if found in a physics textbook would raise eyebrows.

John Rennie

I think you're taking my comment excessively literally

DanielSank

@JohnRennie Well, online communication happening without facial cues makes that somewhat necessary at times.

Also no vocal cues.

0celo7

@JohnRennie I learned about a new kind of cohomology today

It's scarier than de Rham, but easier to compute

John Rennie

4:27 AM

@DanielSank in this case the lack of visual cues leaves me unsure if you really don't see what I am getting at or whether you're just criticising my way of saying it.

0celo7

@JohnRennie Something curious: the Ricci tensor and scalar curvatures satisfy $R_{ij}R^{ij}\ge \mathrm{scal}^2/n$.

John Rennie

I saw your statement of this earlier but didn't quite get it. Isn't $R_{ij}R^{ij}$ just the contraction of the Ricci tensor i.e. the scalar curvature?

0celo7

No?

$\mathrm{scal}=R^i{}_j=R_{ij}g^{ij}$

The proof fails for Lorentzian manifolds, naturally

For a Riemannian manifold we can put an inner product on the space of 2-tensors via $(A,B)=g_{ij}g_{kl}A^{ik}B^{jl}$

Then $(\mathrm{Ric},g)=\mathrm{scal}$

apply Cauchy-Schwarz to this.

DanielSank

@JohnRennie I think I know what you mean, but the language is vague enough and the subject touchy enough that I'd recommend more precise language.

Note that my comment on your meta post simply asked for clarified meaning.

0celo7

@JohnRennie It's a generalization of the inner product $(A,B)=\mathrm{tr}(AB)$ on matrices

John Rennie

4:36 AM

@DanielSank Is it really a touchy subject? Why is it surprising that I think answers here should be of textbook quality? That's probaby more of an ideal than a realistic target, but it seems a good thing to strive for.

@0celo7 I suspect I don't understand the notation well enough to know what's going on here.

0celo7

@JohnRennie There is a symmetric, positive definite bilinear form on $\mathfrak{gl}(n)$ given by $\langle -,-\rangle:\mathfrak{gl}(n)\times\mathfrak{gl}(n)\to\Bbb R, (A,B)\mapsto \mathrm{tr}(AB)$

This can be generalized to any tensor space using the metric

And to any bundle over a compact base by using integration

In particular, we have $\langle A,B\rangle \le\sqrt{\langle A,A\rangle}\cdot\sqrt{\langle B,B\rangle}$

$\langle \mathrm{Ric},g\rangle=g_{ij}g_{kl}R^{ik}g^{jl}=R^{ij}g_{ij}=\mathrm{scal}$

$\langle\mathrm{Ric},\mathrm{Ric}\rangle=R_{ij}R^{ij}$

$\langle g,g\rangle=n^2$

whoops, too used to GR :)

hmm, did I screw up the squares

No, it's $\langle g,g\rangle=g_{ij}g_{kl}g^{ik}g^{jl}=\delta^k_j\delta_k^j=\delta^i_i=n$

better

So $\mathrm{scal}\le \sqrt{R_{ij}R^{ij}}\sqrt{n}$

@JohnRennie make sense now?

John Rennie

Well I now see what you're doing, but understanding it all is a different matter :-)

Sorry if I seem inattentive. I'm reindexing some SQL databases - which is why I'm up at 5 a.m. on a flipping Sunday!

0celo7

@JohnRennie The only issue is proving that $\langle-,-\rangle$ is actually an inner product

which is something I trust Dr. Petersen on :)

that's probably a folklore theorem

@JohnRennie do you know what those are?

@JohnRennie No clue what that is

John Rennie

4:53 AM

Jesus Christ I have four server down alerts :-(

0celo7

oh, you have to expand the tensors into a basis

and then do...something

not hard, just tedious

John Rennie

Phew, false alarms :-)

Sir Cumference

Ahoy

0celo7

let's calculate $\langle A,A\rangle$

$A^i_jA^j_i$

hmm

That's probably just a sum of squares

John Rennie

BTW I listened to the 2Chainz track you mentioned a couple of days ago, but it wasn't really my thing. I'll give the 2Chainz mixtape a miss.

0celo7

5:06 AM

Birthday song?

Fantastic song

Just put it on

She got a big booty so I call her Big Booty.

John Rennie

I have a theory that the music you listened to in your teenage years moulds your musical preferences and it's hard to escape that in later life.

0celo7

Probably the most profound thing...ever

I'm probably being stupid

why is the trace of $A^2$ positive

Jester Tran

What is the best book for learning/improving logical reasoning?

John Rennie

As a teen in the 70a I was listening to a combination of hard rock (Sabbath, Zeppelin etc) and prog rock (Pink Floyd, Yes, Genesis). So that's what I'm stuck with.

0celo7

$\mathrm{tr}(A^2)=\sum_{ij}A^i_jA^j_i$

????

John Rennie

5:08 AM

@JesterTran I think we'd need a bit more context. What sort of things are you trying to reason about?

0celo7

in the symmetric case it's trivial

what am I missing :/

Jester Tran

@JohnRennie Drawing conclusions from complex information

John Rennie

@JesterTran that doesn't really help. For example if you're asking about understanding international politics it's unlikely anyone here can help.

0celo7

Listen to Trump and Farage speeches @JesterTran

...what am I doing wrong

Sir Cumference

Back

Oh God, don't listen to Trump speeches

0celo7

5:12 AM

$A^i{}_jA^j{}_i$

ARGH

John Rennie

@0celo7 Listening to Trump and Farage speeches?

Sir Cumference

^

0celo7

To improve critical thinking

Sir Cumference

What would Trump know about mathematics?

Or politics?

0celo7

More than you, probably

Sir Cumference

5:13 AM

.-.

0celo7

Oh look at this wise guy

Sir Cumference

Walked right into that one...

John Rennie

@0celo7 BITCHSLAP!

0celo7

@JohnRennie currently failing at matrix algebra :P

Sir Cumference

Anyway, it's down to him and Hillary

Honestly, not sure what to pick

Probably leaning towards Hillary

0celo7

5:15 AM

Hillary has brain damage

Look it up

John Rennie

@SirCumference have you seen the latest polls? Clinton will stroll into the White House.

0celo7

@JohnRennie 100 days out

Sir Cumference

@0celo7 Don't all of us though?

I don't know what I'm saying

0celo7

@SirCumference No, she had a stroke

Sir Cumference

I'm tired

@0celo7 Still preferable over Trump

0celo7

5:16 AM

@JohnRennie If only the GOP wasn't actively sabotaging the God Emperor

Sir Cumference

The guy who's against net neutrality, supports the TPP, etc.

He manages to be on all the wrong sides of debates

John Rennie

What's really damaged him is going after the family of a muslim solder who was killed in action.

Sir Cumference

Damn

Then there's the people who think he'll actually build the wall

0celo7

Trump hates the TPP you idiot

Sir Cumference

Source?

0celo7

5:17 AM

ballotpedia.org/…

Sir Cumference

Fuck

0celo7

If you even bothered to listen to his message, you would know that

Sir Cumference

Just realized my source isn't super good for that

0celo7

He's a populist

Sir Cumference

It says "New studies link autism with vaccines"

0celo7

5:18 AM

You just said the populist supports a super elitist trade deal

Sir Cumference

and "astrologer explains how moon is made of cheese"

0celo7

@JohnRennie Yeah

Sir Cumference

Oye, still against net neutrality

0celo7

I don't know why he did that

John Rennie

@0celo7 and that's the point. You really want someone capable of that level of misjudgement as your president?

Sir Cumference

5:20 AM

@JohnRennie This. This right here.

0celo7

@JohnRennie It's an uncharacteristic misjudgement, which is why it's so curious.

Sir Cumference

Sigh...

0celo7

I'm thinking he was expecting some information to surface and it didn't

Sir Cumference

0celo, what actually makes you want to vote for Trump?

His terrorism "plan"? The wall?

0celo7

I want to make America great again, what kind of question is that

Sir Cumference

5:22 AM

@0celo7 What kind of answer is that

0celo7

Help me with linear algebra and I'll answer

Sir Cumference

Goddammit man this is our country on the line

0celo7

$A^i{}_jA^j{}_i$

hmm

I should work it out in 2D

Sir Cumference

What is this for? College?

0celo7

$A^i_1A^1_i+A^i_2A^2_i$

$A^1_1A^1_1+A^2_1A^1_2+A^1_2A^2_1+A^2_2A^2_2$

...

Sir Cumference

5:25 AM

@JohnRennie You know a lot more about this than I do

Have ya tried helping him out?

0celo7

unless things are symmetric, that's not good

DanielSank

@JohnRennie Site policy and culture is touchy.

John Rennie

@SirCumference 0celo7's grasp of maths is way ahead of mine. I've occasionally helped by acting as a sounding board, but that's it.

Sir Cumference

Huh, wow

0celo7

this is linear algebra :/

DanielSank

5:26 AM

Particularly when we're talking about how to simultaneously maintain quality standards while not pushing away would-be new users.

As you can see in the meta post, people's feelings come into play. So yes, "touchy" is an adjective I think appropriate.

Sir Cumference

@0celo7 Congrats

You're a prodigy

0celo7

not really

DanielSank

But anyway, the main point was about raising eyebrows and textbook style answers.

John Rennie

@DanielSank that isn't the point of Emilio's post though. He's talking about dealing with the most egregious level of crap.

0celo7

Actually, maybe it needs to be $T_{ij}T^{ji}$

DanielSank

5:28 AM

@JohnRennie Unfortunately, "most egregious" and "crap" only make sense when someone passes judgement.

John Rennie

Right, and the point of peer review is that it dilutes away the extremes of opinion.

DanielSank

I think most of what Emilio said made sense (although he went about it so round-about-ly that I almost couldn't tell what the hell he actually wanted), but the changes he actually suggested have nothing to do with levels of crappiness.

@JohnRennie Indubitably.

Sir Cumference

On a side note, I got a job at the Museum of Natural History

DanielSank

Undubiously <-- that should be a real word.

His post could be re-written as follows:

1. We have some pretty awful content, both questions and answers. Some times this stuff survives too long.

2. We should exercise our flagging and down-voting more to deal with this.

3. We can also make a change to how flags are routed so that mods don't have to deal with low quality posts as much.

4. What do y'all think?

0celo7

no, that seems to be correct with the first ordering

DanielSank

5:31 AM

I have no idea why there was so much wasted space going on and on about how bad some of the content is. That's totally irrelevant to the community effort he asked for and the slight workflow change he proposed.

John Rennie

@DanielSank I think I agree with all of the above

DanielSank

@JohnRennie k

John Rennie

I also can't see any evidence from the comments or votes in that question and answers for the subject being touchy.

DanielSank

@JohnRennie I am still confused about which part of Emilio's so-called "proposal" you like.

John Rennie

@DanielSank all of it

DanielSank

5:33 AM

@JohnRennie How about the part where Emilio talks about drawn out debates that fatigue everyone?

@JohnRennie oh

Sir Cumference

So, uh, Hohmannfan sent me this

kurims.kyoto-u.ac.jp/~motizuki/…

Anyone know what that paper is about?

John Rennie

But if I'm honest my answer was more of a response to the other answer than a direct answer to Emilio. I wanted to provide a counteranswer to see how people voted.

0celo7

you've linked it before

it's a meme paper

we've been over this

Sir Cumference

@0celo7 I know you've said that

DanielSank

@JohnRennie Unfortunately there are never enough votes in meta to really know much.

Sir Cumference

5:35 AM

But it looks like a real paper

DanielSank

Rarely, in any case.

Sir Cumference

I'm going to assume it's real

DanielSank

I find that somewhat frustrating.

John Rennie

@DanielSank the voting patterns are clear though :-)

DanielSank

Relatedly, I think a major problem with our site is that people don't vote enough, up and down.

Me included.

Sir Cumference

5:36 AM

@0celo7 Plus it's from the Research Institute for Mathematical Studies

A legit site

DanielSank

For me the problem is at least partially that I dislike the -1 from down votes, and also that my reaction to most of the question I read is "what the hell is this person asking?".

I comment a lot asking people to focus their question more.

John Rennie

Well, this is going to sound soppy, but I really believe this site can make the world a better place - well, the world of physics at least. And being (partially) retired I have the free time available to devote to this end.

But you won't make the world (of physics) a better place by posting answers that will get students into trouble if they repeat them in their exams.

DanielSank

@JohnRennie I think this site makes the world better too. That's an objective assessment, and not soppy :-)

@JohnRennie Agreed...

0celo7

I need to sleep

DanielSank

That's... what down votes and flags are for.

0celo7

5:39 AM

doing algebra at 1:40 isn't working

cheerio

John Rennie

Well that's all my answer to Emilio's post says

Sir Cumference

@0celo7 'Night

DanielSank

Uh, yeah... but most of Emilio's post is (at least for me) almost impossible to understand.

For flagging: use the Very Low Quality flag for answers which are complete nonsense, such as

incoherent gibberish
anything not parseable as English text
answers posted in another language
as well as answers that are wrong, or based on non-mainstream physics, that you think are flat-out incorrect, so completely incorrect that no amount of editing can make it useful or constructive, and so completely incorrect that it is actively harmful to the site and its standing.

Do not use this flag for:
followup questions

0celo7

@SirCumference I was doing it completely wrong

Sir Cumference

Wait what

Did that just hit you

0celo7

5:41 AM

I figured it out when I laid down

yeah

DanielSank

So uh, what the hell does he mean to not use the flag for followup questions and comments?

Is his point just that we're misusing the flags?

0celo7

I raised an index wrong lol

John Rennie

Yes, I agree that it could have been more concisely written e.g. your summary above. But he and I are in agreement about the way the PSE should be operating.

Sir Cumference

Ironic. When you stop thinking about it, it comes to you

0celo7

@JohnRennie you're the GR head, you should have pointed that out

DanielSank

5:41 AM

Why did it take him two screens tall to say "guys, use the flags in the following way"?

John Rennie

Well there's some history to this.

DanielSank

What, no dude that message I just posted is a copypasta from Emilio.

John Rennie

It stems from arguments about using the Low Quality flag. And that's an argument that has been simmering for a while.

DanielSank

@JohnRennie Emilio's post didn't propose a way the site should be operating. It told me that there's are many low quality posts, told me to use flags, and suggested changing the timeout for mod visibility on flags.

@JohnRennie I didn't get that from the meta post.

I think what I'm trying to say is that your answer says "I agree" but I have no idea what you agree to because Emilio's post is so hard to understand.

It's like there's a secret communication between you two that I'm not getting.

So I have no idea what you guys are agreeing on, or how the site is going to change, if at all.

John Rennie

Emilio is basically saying flag crap as low quality then vote to delete it.

I'm saying flag crap as low quality then delete it.

I just provide an impassioned argument to support that point of view.

DanielSank

5:45 AM

I'm just so confused.

When I go to a question or answer and click "flag", there is not a "low quality" option.

So what is everyone even talking about?

I feel like I'm in the twilight zone.

Jeez, maybe the most useful part of Emilio's post is the one explaining how the low quality queue works. It would be nice to have that laid out more explicitly with screenshots, etc.

Right now, I simply have no idea what his post actually means.

John Rennie

Sir Cumference

Wtf

DanielSank

@JohnRennie I don't have that option.

Sir Cumference

"99 flags remaining"

How long have you been here?

DanielSank

It must be a rep issue, in which case Emilio's post just became turbo-confusing because most of the readers can't even see the options he's talking about.

John Rennie

5:49 AM

@DanielSank There's no special significance to that answer, I just selected it to show the LQ flag option.

@SirCumference you get 100 flags a day. I've only flagged once today so I have 99 left today. Tomorrow it goes back to 100.

DanielSank

@JohnRennie Yes, did you read my message saying that I don't get that option?

Sir Cumference

@JohnRennie Dude, you'd have to have been here forever to get 100 flags...

John Rennie

@DanielSank Look at:

-3

A: Will an emf be induced?

Case 3: When the axes of the bar magnet and the coil are the same, magnetic flux enters the magnet from south pole and flux comes out from the north pole. When we keep the magnet stationary and rotate the coil about its vertical axis, which is perpendicular to the axis of the bar magnet,the flux...

and see if you get that flag option

DanielSank

@JohnRennie Yes, I have the "low quality" option, so it's about votes?

John Rennie

@SirCumference ah right. The number of flags increases with your rep.

Sir Cumference

5:52 AM

@JohnRennie IIRC, it increases depending on your approved flags:declined flags ratio

Although the algorithm itself is weird

John Rennie

@DanielSank The LQ option doesn't always appear for me either. I don't understand the rules for when you do and don't get that option but presumably they are documented somewhere.

Sir Cumference

Jesus, 1700 flags?

._.

DanielSank

@JohnRennie I see.

John Rennie

Now does it all make sense? :-)

DanielSank

I don't know why I'm in such a huff about this.

Sir Cumference

5:53 AM

-11

Q: Isn't searches for dark matter crazy effort?

There are a lot of crazy quests in astrophysics, one of them is searches for dark matter. How someone could observe dark matter while it is far away?

dark-matter

This question is amazing

DanielSank

I think I'm annoyed that Emilio is trying to give us a path forward on something important but the post is so wandering that I can't tell what's actually going on.

It's like reading a textbook on a subject you love but finding the wording or notation so convoluted that you don't learn anything. I always really hated that feeling.

John Rennie

But all Emilio wants is to make this site a better place for the world of physics, and that's what I want too and I'm sure what you want as well.

DanielSank

@JohnRennie Oh for... of course. That doesn't help clarify what he's actually proposing in the meta site.

Come on, dude, that's like me asking for details on your plan to save puppies, and instead of answering you say "I love puppies, don't you love puppies? Don't you want to help puppies too?".

John Rennie

He's proposing flagging the most egregious crap as LQ and voting to delete it.

DanielSank

Yes, I want to help puppies.

@JohnRennie Ok... but I can't flag eggregious crap as LQ...

The options isn't there, sometimes, for some reason.

So I don't know what to do.

John Rennie

5:58 AM

I suspect the answer must have attracted some downvotes for the option to appear. I find that in practice the option has always been there when I've wanted it.

Maybe the answer has also to have been posted some minimum time ago.

DanielSank

@JohnRennie I see. Well, if the whole point of Emilio's post is to say what you just said in the chat room, perhaps you'd suggest he edit?

I can't be the only one who is mystified by that wall of text.

John Rennie

@DanielSank Hmm, I must admit that I've chatted with Emilio before about this so I knew what he was getting at. I hadn't stopped to think that his post would have been incompressible to non-initiates but I have to concede that you have a point.

But his concrete proposal is that from Monday we start flagging wrong answers as low quality (assuming that option appears).

And that's a procedural chance because at the moment the LQ flag is supposed to mean only that a post is incomprehensible.

DanielSank

@JohnRennie Ok, now I know.

But other people reading that meta post won't.

Most people won't even read it.

John Rennie

I'm a bit surprised that no mod has commented because this will affect what appears in their review queues. Maybe they are waiting to see what the consensus view is.

DanielSank

@JohnRennie Ah.

Ok, I've decided to not care about this.

Thanks for explaining what's going on.

~Sigh~, I'm turning into a type 4 user.

:(

John Rennie

6:09 AM

@DanielSank I care about this. I care passionately about it.

DanielSank

@JohnRennie Great.

I care about site quality, but I decided to not care about the issue raised by Emilio until someone explains it clearly.

user147690

6:39 AM

What are these type 1 and type 4 in reference to?

John Rennie

@AlexClark see:

Jul 31 at 7:33, by peterh

558

A: Why is Stack Overflow so negative of late?

Why is Stack Overflow so negative of late? I hate to pile on, but I couldn't resist summarizing the problem. And I apologize ahead of time for any potentially offensive language that I might use. Basically there are 4 camps of users on Stack Overflow: The "caretakers" who want to keep the...

Sanya

7:42 AM

@JohnRennie that's a really good post you've written on meta - although I was quite surprised to read, probably for the first time, that PSE is mainly educational

John Duffield

7:56 AM

@Sanya : thanks. I've used gimp, and I've got Microsoft office 2013 on this laptop, it includes Publisher. The sort of pictures I want to do are physics illustrations. For example the other day I was trying to do a picture like this but with the grid lines bulging out.

CuriousOne

@peterh Because there are absolutely no formal criteria for correctness. Physical derivations are usually nothing but an imaginative use of mathematical techniques. Very often it takes decades to clean up the physicist's mess and often the cleanup is not even needed because the resulting theory is not even correct. I take that back, the resulting theory, so far, has never been correct. That's not how mathematicians work.

John Duffield

@vzn : I share your sentiment.

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