The h Bar

in general, $A_{(\alpha\beta)}=\frac{1}{2}(A_{\alpha\beta}+A_{\beta\alpha})$. Is there any convention regarding multi-indices, and the notation $A_{(\alpha\beta)}$ when $\alpha,\beta\in[1,n]^m$?

e.g., $A_{(\alpha\beta)}=\frac{1}{m!}(A_{(\alpha)(\beta)}+A_{(\beta)(\alpha)})$ or something like that?

0celoñe7

You poor child.

This is a level of index wizardry even we relativists don't encounter...

You have ascended to PhD level index gymnastics.

Anonymous

Isn't AFT a PhD guy?

Slereah

The general rule is $$T_{(\alpha\beta\gamma...)} = \frac{1}{n!}\sum_{p \in \text{permutations}}T_{p(\alpha\beta\gamma...)}.$$

AccidentalFourierTransform

7:17 PM

I wish

Anonymous

:P

0celoñe7

@Slereah In his notation, $\alpha$ is a multiindex.

Emilio Pisanty

@0celoñe7 $$\LARGE 🤦$$

YMMV depending on whether your font encodes for it or not

0celoñe7

@EmilioPisanty I can't seem to copy that

YMMV?

Slereah

@0celoñe7 i'm sure it's possible to prove something from that definition

Emilio Pisanty

7:18 PM

@0celoñe7 🤦 maybe?

Slereah

your mileage may vary

Emilio Pisanty

^

but I think the simplest encoding of a facepalm into unicode is the multicharacter combination https://upload.wikimedia.org/wikipedia/commons/3/3b/Paris_Tuileries_Garden_Face‌palm_statue.jpg

0celoñe7

I mean like a Japenese style one

@Mostafa had a good one

@EmilioPisanty 🤦

Emilio Pisanty

@0celoñe7 yeah, I can see that

Anonymous

List of emoticons

This is a list of notable and commonly used emoticons, or textual portrayals of a writer's moods or facial expressions in the form of icons. Originally, these icons consisted of ASCII art, and later, Shift_JIS art and Unicode art. In recent times, graphical icons, both static and animated, have joined the traditional text-based emoticons; these are commonly known as emoji. Emoticons can generally be divided into three groups: Western (mainly from America and Europe) or horizontal (though not all are in that orientation); Eastern or vertical (mainly from east Asia); and 2channel style (originally...

Anonymous

7:23 PM

This is a good reference :D

AccidentalFourierTransform

Slereah

there is but one good emoji

🤔

AccidentalFourierTransform

how come no one ever told me this

Slereah

$$\huge{🤔}^{\large{🤔}^🤔}$$

$$\Huge{🤔}^{\huge{🤔}^{\Large{🤔}}}$$

4

0celoñe7

@AccidentalFourierTransform apparently calling people savages is not allowed here

Slereah

7:25 PM

really makes you think

0celoñe7

but let's just say that (---+) is...

AccidentalFourierTransform

savage is not allowed?

since when?

0celoñe7

I got banned for an hour the other day

AccidentalFourierTransform

oh, but that was because it was you

everybody else can say savage

Slereah

$$^{^{\LARGE{🤔}}\huge{🤔}}_{_{\LARGE{🤔}}\huge{🤔}}\Huge{🤔}_{\huge{🤔}_{\LARGE‌{🤔}}}^{\huge{🤔}^{\LARGE{🤔}}}$$

5

AccidentalFourierTransform

7:27 PM

Slereah pls

0celoñe7

lol

@AccidentalFourierTransform Do you think I get unnecessarily flagged?

Emilio Pisanty

@Slereah that's possibly the best message ever posted on the h bar

Slereah

$$^{^{\LARGE{🤔}}\huge{🤔}}_{_{\LARGE{🤔}} \huge{🤔}}\overset{\huge{🤔}}{\underset{\huge{🤔}}{\Huge{🤔}}}_{\huge{🤔}_{ \LARGE{🤔}}}^{\huge{🤔} ^{\LARGE{🤔}}}$$

0celoñe7

rekt

Slereah

For some reason the underset won't go through

Emilio Pisanty

7:28 PM

yeah, that dinnt work, did it

Slereah

I guess we can only think so much

Emilio Pisanty

@Slereah add spaces

right before the offending LARGE

ACuriousMind

There.

Mod abuse!

Mostafa

@Slereah c'mon. fix it. we want to star that

AccidentalFourierTransform

@0celoñe7 no, you deserve every single one them flags

0celoñe7

7:29 PM

@ACuriousMind how do I report

Slereah

It's a bit malformed

But it really makes you think

0celoñe7

@AccidentalFourierTransform what the hell?

AccidentalFourierTransform

hell? oh boy thats a flag

Emilio Pisanty

@Slereah yeah, that doesn't display on the star board

Slereah

that's because it's too long to display fully on the starboard

Emilio Pisanty

7:30 PM

which is why it should be removed from the star board

Mostafa

@EmilioPisanty What's wrong

Emilio Pisanty

2

A: Comment "spreaded" all over the webpage - unable to edit, unable to delete

There's a subtle bug in your LaTeX code, which somehow broke it between your answer-box preview and the comment box. The formula looks correct, but if I just copy-paste your formula (removing some code in the middle so it doesn't break the answer display) and add then dollar signs, I get this $$...

↑ relevant

if there's too much text without spaces, some bit of code along the chain will sneak in some zero-width spaces, which is why you get those weird $\LARGE A$

AccidentalFourierTransform

so, Hamiltonian mechanics lives on the cotangent bundle. Where does Hamiltonian field theory live? the cojet bundle? is that even a thing?

Slereah

@AccidentalFourierTransform The Legendre bundle

It's very ugly

$$\Pi = V^*Y \wedge (\bigwedge^{n-1} T^* M)$$

AccidentalFourierTransform

google declares that doesnt exist

Slereah

7:34 PM

then you didn't google very hard

AccidentalFourierTransform

The Legendre bundle

Slereah

arxiv.org/abs/1108.5531

AccidentalFourierTransform

I found Legendre manifolds

is that it

it does look ugly

Slereah

cds.cern.ch/record/271943/files/9411089.pdf

Yeah

I wanted to do my book entirely in fancy bundle language

Then I saw the legendre bundle

And I said maybe not

AccidentalFourierTransform

huh, interesting

thx

Slereah

7:40 PM

Even Lagrangian field theory on the bundle is fairly ugly

With the jet bundles and the graded algebras

But Hamiltonian is even worse

0celoñe7

Does it even matter?

Does the fancy language matter at all?

AccidentalFourierTransform

poor Hamilton. His mechanics and his quaternions - nobody likes his inventions

0celoñe7

:(

Slereah

There's a quaternion version of GR

0celoñe7

there's a book on it I've considered reading

decided I had better things to do

not even sure what a quaternion is

Slereah

7:43 PM

there's still plenty of quaternions used in physics

It's just that it is hidden

Because $\mathfrak{sl}(2,C) \approx \mathbb{H}$

Mostafa

ACuriousMind

@Slereah $\mathbb{H}$.

$\mathbb{Q}$ are the rationals.

0celoñe7

Lol

Slereah

A bit conceited of Hamilton to name them after himself

0celoñe7

@AccidentalFourierTransform another book for you press.princeton.edu/titles/1015.html

you basically want all Giaquinta books

@ACuriousMind have you ever proved something in notes, but didn't want to TeX it out of fear you find a mistake?

Right now I can claim this is true and reference [Unpublished]

[Conversation in men's room]

AccidentalFourierTransform

7:51 PM

you can reference [work in progress] and then kill yourself

ACuriousMind

@AccidentalFourierTransform Could we...not tell other people to kill themselves, even in jest?

@0celoñe7 Not really

Mostafa

@ACuriousMind What about suicide? can we talk about our (possible) suicide plan?

@0celoñe7 as a mathematician, how do you feel when you see this? ^

ACuriousMind

@Mostafa Talking about your own suicide is either a) a grossly inappropriate joke or b) a serious issue you should discuss with the relevant helplines and a psychologist. Neither belongs into SE chat.

3

0celoñe7

Jeez

What is with this chat this weekend?

@Mostafa meh?

it's number theory

whatever

Mostafa

@ACuriousMind This case (b) is totally wrong. People who decide to kill themselves usually talk about their decision in online forums.

If I ever decide to kill myself I'll certainly tell others about it somewhere online (most probably here)

0celoñe7

8:05 PM

@ACuriousMind the best proof

Anonymous

@Mostafa Umm, can we stop this now? It's not funny.

Mostafa

@Blue People are supposed to help a suicidal person, instead of telling him/her to stop because it's annoying!

0celoñe7

good point

ACuriousMind

@Mostafa I'm not saying that I'll just block a user I genuinely believe to be suicidal "because they are annoying", and I am insulted you would think that. There actually is a special feature to notify Community Managers about suicidal users, who will then reach out to the user.

Anonymous

@Mostafa How do you ever differentiate between a person who is trolling and raising fake suicide alerts and one who is telling the truth? Also, it is impossible for us to help you even if you actually intend to carry out the act. Heck, we don't even know who you are and where you stay.

Mostafa

8:13 PM

@Blue No it is not impossible at all to help a suicidal person online. Sometimes just feeling that somebody likes him and wants to help him or understands him is enough for that person to change his mind

vzn

reminds me of this story in the news dailymail.co.uk/news/article-4626372/…

Anonymous

@Mostafa If I feel that the person is not trolling then obviously I'd try to pacify him and prevent him from doing so.

Anonymous

If it were you, obviously most people here would do the same.

Anonymous

On the other hand if it were some random visitor to the chat room, then I don't know....

0celoñe7

@ACuriousMind Do you know of a good Tikz tutorial? This proof is getting so convoluted I have to draw pictures.

ACuriousMind

8:24 PM

@0celoñe7 I don't know tikz (in can barely draw commutative diagrams, but that's it), you should ask Danu or at tex.SE, I guess.

Anonymous

@0celoñe7 This might help.

0celoñe7

I really just need to draw boxes $P\subset C'\subset R\subset C\subset M$

then draw a bunch of them covering the boundary of something

@Blue thanks, czeching it out

AccidentalFourierTransform

. media.giphy.com/media/Qqq8b2K5qsg8M/giphy.gif

MRW Legendre bundle

yeah right, thank you kind mod

do supervector spaces really capture what we want a fermion field to be?

I want the components of the vectors to anti-commute, not the vector themselves!

ACuriousMind

8:42 PM

@AccidentalFourierTransform What do you want your fermion field to be?

AccidentalFourierTransform

I want a standard vector space, over an anti-commuting field

not an anti-commuting vector space (or algebra)

does that make any sense?

ACuriousMind

@AccidentalFourierTransform Ah, yes, sort of, although I am not sure why you want the space to be over an anitcomuting field

I mean, the fermionic operators are still just operators on a Hilbert space, you should be able to multiply them with complex numbers, not by some weirdo skew-field numbers

AccidentalFourierTransform

well, I want $\psi^\alpha\psi^\beta=-\psi^\beta\psi^\alpha$, where $\psi^\alpha$ are the components of $\psi$ with respect to some basis $e_\alpha$

so I want $\psi=\psi^\alpha e_\alpha$, with $\psi^\alpha$ numbers in the field of scalars

I want $\psi^\alpha$ to be anti-commuting, not $e_\alpha$

Im thinking of (super) classical field theory BTW

0celoñe7

superclassical field theory?

What has the world come to

AccidentalFourierTransform

oh shut up already and get off your high horse

<3

0celoñe7

8:52 PM

@AccidentalFourierTransform Prove my damn boundary regularity and I will never say a negative word about physics again

ACuriousMind

@AccidentalFourierTransform Actually, in classical field theory, why would you want to have $\psi^\alpha$ anticommuting?

Speaking of "commutation" for a classical field doesn't make any sense :P

0celoñe7

@ACuriousMind That's why it's superclassical, clearly.

AccidentalFourierTransform

idk

I give up, physics is broken

ACuriousMind

Classically, what you need is "super-Poisson bracket anticommuting", which follows from the correct definition fo the super-Poisson bracket for the spinor fields.

0celoñe7

lol

ACuriousMind

8:54 PM

@0celoñe7 It's not superclassical field theory, it's classical superfield theory :P

AccidentalFourierTransform

classical field supertheory

0celoñe7

^

AccidentalFourierTransform

@ACuriousMind im not at that point yet. Im thinking of Lagrangian classical superfield theory :-P

so e.g., $q^i(t),\dot q^i$, i=1,2,...,n are the coordiantes

and I would expect them to anti-commute

0celoñe7

@ACuriousMind How do I insert a lemma into a proof?

and then proof of the lemma

if I do the full thing it looks strange

I wouldn't want it numbered

ACuriousMind

@0celoñe7 You don't, I don't like when people do that :P

@AccidentalFourierTransform Not following you, I'm afraid

AccidentalFourierTransform

8:57 PM

@ACuriousMind Im not really following myself either I guess

as I said, physics is broken and nothing makes sense

0celoñe7

@ACuriousMind the lemma does not make sense outside of the proof of the main theorem, it's about a construction

AccidentalFourierTransform

am I suspended or not?

oh, now it works

Dawood ibn Kareem

9:34 PM

@ACuriousMind Don't need to. There's this thing called the Internet that seems to work better.

Emilio Pisanty

¬¬

outta votes

0celoñe7

9:52 PM

@ACuriousMind are you willing to read my regularity proof?

I don't know why it took me like a month, pretty straightforward in the end

I distracted myself with the normal vectors, but those are actually irrelevant in the end.

heather

@EmilioPisanty already vtc'd it

there seems to be an especially large amount of junk today

or maybe it's just that i'm going through the general-physics tag

Emilio Pisanty

@heather don't

it's ready to be removed en masse

if you really want to nail that coffin shut, fix the links in this one physics.meta.stackexchange.com/a/5032/8563

heather

okay

what's the numerics tag for?

ACuriousMind

10:10 PM

@0celoñe7 You know that I don't really care about PDEs :P

Emilio Pisanty

@heather at least in principle, that's a subset of computational-physics

heather

ah. okay then.

ACuriousMind

@heather It's for numerics. I'm not entirely sure how it's supposed to differ from numerical-method, though.

heather

i've edited two out of the three, but i don't know how to edit the "expressions that equal 1" one.

0celoñe7

@ACuriousMind Maybe...but you can spot obvious errors in proofs.

heather

10:12 PM

could a mod delete that?

Emilio Pisanty

12

Q: Binary Black Hole Solution of General Relativity?

This is rather a technical question for experts in General Relativity. An accessible link would be an accepable answer, although any additional discussion is welcome. GR has well known solutions relating to single Black Holes: Schwarzchild, Rotating & Rotating with Charge. These solutions demons...

now, as to how a question can have both numerics and analyticity, though...

0celoñe7

@EmilioPisanty trying to match numerical solutions to known analytical ones

(I am doing that)

ACuriousMind

@heather As a general rule, we do not delete questions with upvoted answers without very good reasons.

Emilio Pisanty

but shouldn't analyticity be reserved for complex analyticity?

i.e. shouldn't analyticity be synonymous with meromorphicity?

0celoñe7

@EmilioPisanty Uh. That seems like a very narrow tag.

I interpreted it as "closed form solution" analytic

Emilio Pisanty

10:14 PM

@0celoñe7 well, as opposed to what?

0celoñe7

@EmilioPisanty Does anyone actually use the tag in the way you suggest?

And is it a worthwhile tag?

Emilio Pisanty

@0celoñe7 I reckon it's about an 80-20 split

but maybe most of the complex-analysis ones could be re-tagged analytical-continuation, which is less ambiguous

@ACuriousMind seriously, though, what's to be done with this one?

-5

Q: Are there any expressions in physics which always equal 1?

Are there are any mathematical expressions in physics that will always be equal one or to a number which is almost equal to one. If there are any I would highly appreciate if you could show me and tell me the name of it/them.

general-physics+

0celoñe7

@ACuriousMind So I take it you're declining?

@EmilioPisanty lol

Emilio Pisanty

it would be enormously beneficial if we can remove that occurrence of the tag

ACuriousMind

@EmilioPisanty Retag as big-list? :P

Emilio Pisanty

10:19 PM

@ACuriousMind and then get in the same trouble when we decide to remove big-list in two years' time?

yeah, I guess that's an acceptable solution

ACuriousMind

Yeah, that wasn't an entirely serious suggestion

It's a difficult question

Emilio Pisanty

terminology and notation?

laws-of-physics? (ideally not!)

or maybe we could tag it bad-question

ACuriousMind

@0celoñe7 I think so, yes

In an optimal world, that question would have been closed before anyone answered it, and the roomba would just have silently axed it. In the imperfect world we live in, it stayed open for a year and attracted two upvoted answers.

Emilio Pisanty

@ACuriousMind yes, but we don't live in an optimal world. we live in a world where that lived long enough for someone to leave this shining example of an answer.

ACuriousMind

Yeah. Well, that question is just so bad that I can't see any tag fitting, honestly.

Emilio Pisanty

10:24 PM

yeah, exactly

ACuriousMind

I mean, the only reason it has general-physics is because I did that in desparation to remove the mathematical-physics tag it had initially!

Emilio Pisanty

@ACuriousMind yeah, well

whatever tag we choose, it's just shoving a smelly hot potato onto that tag

> If there are any I would highly appreciate if you could [...] tell me the name of it/them.

terminology?

ACuriousMind

Ugh. I'm beginning to reconsider whether "this question is just horrible" may be a "very good reason" to just delete it and be done with it

0celoñe7

@ACuriousMind That's Not very Nice...

Emilio Pisanty

@0celoñe7 it wasn't nice to provide answers to that kind of a clonker of a question, and then leave it to others to clean up

ACuriousMind

10:29 PM

@0celoñe7 It's not a judgement of the user - but that question is just a horrible fit for our site. It doesn't fit in any tag, it doesn't have any clear scope...

0celoñe7

@ACuriousMind And me saying things about the JEE are not judgements of anyone either, yet it's still Not Nice.

Emilio Pisanty

I've got an idea

0celoñe7

I agree that it's a horrible fit, but your phrasing is indeed not very nice.

Emilio Pisanty

migrate it to maths

ACuriousMind

@EmilioPisanty Hm, meta seems to indicate the proper action is indeed deletion.

@0celoñe7 That was about a continued pattern of behaviour and not a one-off remark and I'm not particularly inclined to revisit this topic right now.

Emilio Pisanty

10:36 PM

maybe tag as untagged, then?

ACuriousMind

It says the untagged tag does not exist, do I want to create it?

Somehow doesn't really seem to resolve the issue, does it?

heather

can we tag it as please-destroy

dmckee

@EmilioPisanty I'm afraid I cut that avenue off some time ago:

33

Q: Do not allow users to tag questions with "untagged"

It seems that there is an automated process that can result in questions getting tagged as untagged, but it should not be possible for users to generate questions with this tagging. (The example is from SciFi.SE, but I think the rule should apply network wide.) If no other mechanism exists the m...

feature-request status-completed tags stackexchange

Bernardo Meurer

Heya folks

@dmckee ::waves::

0celoñe7

@BernardoMeurer Hi

Bernardo Meurer

10:39 PM

@0celoñe7 Yo

dmckee

'sup?

Bernardo Meurer

How's the computer?

0celoñe7

@BernardoMeurer Nothing but problems

Bernardo Meurer

@dmckee Just chilling in Rio, preparing to move to SB, getting my ass kicked trying to get housing

0celoñe7

I can't play Morrowind at 60 fps

Bernardo Meurer

10:40 PM

Why?

0celoñe7

Nor Ass Creed Unity

dmckee

To err is human. To really screw things up you need a computer.

Bernardo Meurer

ACU is a hard to run game

Morrowing is old AF so idk

0celoñe7

@BernardoMeurer ...I have 100+ mods. According to the internet, the game engine runs on one core. I might be killing it.

Bernardo Meurer

Lol

There we go

dmckee

10:41 PM

@BernardoMeurer There is a sort of shelter-thingy in the park in Isle Vista where the homeless folks used to hang out...

0celoñe7

@BernardoMeurer So clearly I must boost my single core performance...

Bernardo Meurer

@dmckee Thanks for the help

My plan B is to assassinate @DanielSank 's roomate and take his place if I can't find something ASAP

@0celoñe7 Yes

Or use less mods :)

0celoñe7

@BernardoMeurer They are almost entirely graphics mods.

These insane people have hacked reflections and shadows into the game

I don't think the original had either

Bernardo Meurer

TES modders are a thing of beauty

heather

@dmckee to err is human. to arr is pirate.

@EmilioPisanty could one tag with laws-of-physics?

Bernardo Meurer

10:43 PM

@dmckee Get me a house

0celoñe7

@BernardoMeurer As for ACU...it's just a buggy mess. I'm not too concerned with it not running well.

Emilio Pisanty

@heather that one is already problematic as hell

0celoñe7

It runs well most of the time but sometimes in cutscenes it maxes out the GPU.

heather

@EmilioPisanty yeah, true.

dmckee

@0celoñe7 Decades of anti-growth policy combined with lots of people wanting to live there mean that the housing situation is an total nightmare.

heather

10:44 PM

i've been looking around, and I see soft-question also possibly being one to slim down/remove

Emilio Pisanty

@dmckee what's your thoughts on just deleting that one?

Bernardo Meurer

¯_(ツ)_/¯

@dmckee Tell me about it

0celoñe7

@dmckee What?

dmckee

@0celoñe7 The stupid screen scrolled as I was clicking. Was meant to Bernardo.

@EmilioPisanty The tag [laws-of-physics]? I can't think of a reason to keep it.

Emilio Pisanty

-6

Q: Are there any expressions in physics which always equal 1?

Are there are any mathematical expressions in physics that will always be equal one or to a number which is almost equal to one. If there are any I would highly appreciate if you could show me and tell me the name of it/them.

general-physics+

@dmckee ↑ this one

Mithrandir24601

10:47 PM

I remember Rise of the Tomb Raider using 6GB of VRAM at 1080p... That was insane. The graphics were astonishing though :)

Bernardo Meurer

DirectX was written by potatoes

0celoñe7

@Mithrandir24601 The 4K textures for Fallout 4 will beat that

Bernardo Meurer

Long live OpenGL and Vulkan

dmckee

Uhm. I usually say 'the users should delete such stuff'.

heather

how do you do an advanced search for questions without a tag?

0celoñe7

10:48 PM

@Mithrandir24601 With them installed the total game size is 110GB

dmckee

BEcause otherwise I am unilateraly taking someone's rep away.

But the answers are clearly trivial.

heather

like with soft-question and without resource-recommendation

Mithrandir24601

@0celoñe7 Yeah, but it's easy to go over 6GB for 4K :P

ACuriousMind

@dmckee I don't think users can vote to delete questions with upvoted answers

0celoñe7

@Mithrandir24601 at 1080p they will do that

heather

10:48 PM

@dmckee and the whole thing is just...i mean, if you don't delete it, how are you going to tag it? it's just bad.

Mithrandir24601

@0celoñe7 Ah. Yikes :o

dmckee

@heather key words +[soft-question] -[resource-recommendation], I think.

ACuriousMind

Or can you vote to delete there, @EmilioPisanty?

0celoñe7

@Mithrandir24601 4K texture doesn't mean you need 4K to see them. Not really sure what it means :P

Mithrandir24601

@0celoñe7 I'm tempted to try it just to see what it looks like...

heather

10:49 PM

@dmckee thanks

Mithrandir24601

OK... That's... Weird...

0celoñe7

@Mithrandir24601 It doesn't change that much.

Emilio Pisanty

@ACuriousMind just did

don't know if it will work

0celoñe7

@Mithrandir24601 It probably means you won't see upscaling issues at 4K or something.

dmckee

@EmilioPisanty It's showing a pending delete vote now.

0celoñe7

10:50 PM

Or all of the texture files are 4K images.

Who knows

dmckee

I won't feel bad about providing the third such vote. Anyone want to second the motion?

Mithrandir24601

Yeah, there's not a huge difference [read: barely any, if at all] between 1080p and 4K anyway, unless I'm really close to the screen - I don't have a second monitor, though, so there's maybe a difference there

0celoñe7

@BernardoMeurer So after $1600 I can only really say I appreciate the steady 60fps. The fancy graphics are not that amazing.

Emilio Pisanty

@dmckee as in, even if it gets three user delete votes, I don't know whether it would work

Bernardo Meurer

@0celoñe7 Spend more money

heather

10:51 PM

is there a way to search for a question tagged only with a particular tag?

0celoñe7

@BernardoMeurer Give me a link to a 1440p 144Hz Gsync monitor then

dmckee