The h Bar

Slereah

20:00

Or something

0celo7

@loltospoon it should be a differential operator

use difference quotients

Slereah

Why use a numerical method

It's one of the simplest system there is

loltospoon

It's a requirement

Oh, it's a test case for a broader project

If I can make this script work for this simple case, then I can extend it to a general system

Slereah

finite elements, baby

loltospoon

what do you mean?

AccidentalFourierTransform

20:10

@0celo7 yeah, what I want is the matrix representations of the algebra of angular momentum for arbitrary $d$, or at least for $d=2,3,4$

Ill check Zee

0celo7

@AccidentalFourierTransform Who knows

Ask @ACuriousMind

AccidentalFourierTransform

hes mad at me

0celo7

why??

AccidentalFourierTransform

idk

he not returning my calls or texts

he blocked me on snapchat

and I found out that he's on tinder

0celo7

wow

@ACuriousMind you're sleeping on the couch for a while

Jaime Gallego

20:25

Internet does not work aaaaargh

AccidentalFourierTransform

yes it does

Jaime Gallego

I meant my internet connection :-D

AccidentalFourierTransform

so did I

0celo7

@AccidentalFourierTransform why don't you do something nice, like analysis

AccidentalFourierTransform

bc Im watching a movie right now

0celo7

20:41

what does that have to do with analysis

AccidentalFourierTransform

cant do both at the same time

ok, given $\lim_{x\to8}\frac{1}{x-8}=\infty$, prove that $\lim_{x\to3}\frac{1}{x-3}=\omega$

hint: rotations and limits commute

0celo7

$\omega$?

AccidentalFourierTransform

$\omega$.

0celo7

the first uncountable ordinal?

AccidentalFourierTransform

no. $\omega$.

cmon. You can do it.

0celo7

20:44

0

Q: Learning GR: How do I know when to evaluate the metric/Christoffel symbol at a point, and when not to?

I am taking an introductory course in general relativity, and we are following the Carroll book called spacetime and geometry. I've found that he writes his tensor equations without specifying at which point the tensors are to be evaluated. For example, he writes $g_{\mu \nu}$ and not $g_{\mu \nu...

terrible question

AccidentalFourierTransform

lol

0celo7

2

Q: Ricci scalar for a diagonal metric tensor

I was wondering if there is a general formula for calculating Ricci scalar for any diagonal $n\times n$ metric tensor?

general-relativity differential-geometry metric-tensor curvature

lol, that comment is pretty troll

wonder who that was, account is deleted

1

Q: Must states on local algebras of QFT be "backwards-compatible"?

I have (what I believe is) a pretty straightforward conceptual question about Algebraic Quantum Field Theory. On local algebras there exist mathematically possible states that are "not backwards-compatible" in a sense I will define below, and I want to know whether these states get excluded from ...

quantum-field-theory

@Slereah for you ^

Slereah

>using $\mathcal R$ for the algebra

I shiggy diggy

0celo7

what's wrong with it?

Slereah

The standard is $\mathfrak{A}$

0celo7

20:55

why?

DanielSank

Anyone understand this?

0

Q: How to determine light intensity at each frequency in black-body radiation?

I say, when the temperature increase the energy per photon increases which in part decreases the overall wavelengths of the black-body and the intensity increases because of the emission rate. which mean that light intensity at each frequency is determined by the black-body temperature, but this ...

electromagnetic-radiation

Slereah

It stands for "$\mathfrak A$lgebra"

$\mathfrak{Algebra}$

0celo7

oh, is that an A

$\mathfrak A$

Slereah

yes

Emilio Pisanty

@Slereah That's the least helpful mathfrak character ever

0celo7

20:57

$\mathfrak U$

Emilio Pisanty

It stands for "I bet yo$\mathfrak A$ can't guess what this character actually is"

Slereah

It's pretty helpful if you want to write an algebra

0celo7

why not $\mathscr A$ like most people?

or $\mathcal A$ like plebs

Emilio Pisanty

↑ that

↑↑ and that

Slereah

I dunno

Some people seem to like fraktur

0celo7

20:59

I said happy birthday to ACM in fraktur

I bet you can't read it

Emilio Pisanty

@Slereah most characters are OK

0celo7

Lower case fraktur is nice

Emilio Pisanty

most lowercase is ok, except for $\mathfrak{k,w,x,y}$

0celo7

Is that $\mathfrak n$?

Hah

wtf is that

$\mathfrak w$

^I've seen that one used somewhere

$\mathfrak t$

$\mathfrak k$

Slereah

I've seen old russian math papers

They use a lot of fraktur

0celo7

21:01

mathfrak k is stupid

$\mathfrak{abcdefghijklmnopqrstuvwxyz}$

AccidentalFourierTransform

Rocky $\mathfrak w$

0celo7

x and y??? @EmilioPisanty why???

Emilio Pisanty

Uppercase, any of $\mathfrak{AGHIJOPQSTVY}$ is trouble

@0celo7 $\mathfrak x$ vaguely makes it

0celo7

@EmilioPisanty the third one is an H

Emilio Pisanty

there's no excuse for $\mathfrak y$

0celo7

21:02

it's a German eta, clearly

Slereah

What libraries does mathjax have, anyway

Emilio Pisanty

@Slereah who knows

why?

Slereah

wondering what symbols I can make

Emilio Pisanty

oh, no idea

0celo7

I want lower case mathscr

I used to like mathcal but it's pretty bad honestly

$\mathcal B$ is nice

$\mathcal X$ is a swastika

Slereah

21:06

onemathematicalcat.org/MathJaxDocumentation/TeXSyntax.htm

$\amalg$

Weren't you looking for this

0celo7

I figured it out

\amalg

Emilio Pisanty

this is weird

If I ctrl-F on chrome and put ß on the search bar, it matches all the ss's on the page

Slereah

$\cal{ABC}\mathcal{ABC}$

Emilio Pisanty

I want a mathfrak ß just to mess with people

Slereah

cal and mathcal seems identical

0celo7

21:09

what could one use $\bigwedge$ for

Slereah

@0celo7 Repetition of logical conjunction

ACuriousMind is $\cancel{\text{a wiener}}$ great

0celo7

$\checkmark$

Aha!

Yes!

Emilio Pisanty

@0celo7 $\bigwedge_{i=1}^n P_i = P_1\wedge \cdots\wedge P_n$

Slereah

Hm, didn't work

0celo7

@EmilioPisanty why would you ever use such notation though

Slereah

21:11

in case you are doing logic

for instance

if you are using the Craig axiomatization scheme

Emilio Pisanty

$\bigwedge$ that

0celo7

$\checkmark_{\mu\nu\rho\sigma}$

This is the new notation for Riemann tensors

Slereah

Craig's theorem

In mathematical logic, Craig's theorem states that any recursively enumerable set of well-formed formulas of a first-order language is (primitively) recursively axiomatizable. This result is not related to the well-known Craig interpolation theorem, although both results are named after the same mathematician, William Craig. == Recursive axiomatization == Let A 1 , A 2 , … {\displaystyle A_{1},A_{2},\dots } b...

$\bigwedge$ would be quite useful here

0celo7

$\ominus,\oplus$

Emilio Pisanty

also $\odot$

0celo7

21:12

are those circles the same?

Slereah

$\Cap$ Take a look, it's in a book, a reading rainbow $\Cap$

Emilio Pisanty

$\bigodot$

0celo7

sniper dot?

Emilio Pisanty

$\bigodot\bigodot$

0celo7

yeah what's the double intersection thing?

compact intersection?

@EmilioPisanty Tits! (The mathematician, of course.)

Emilio Pisanty

21:13

(before anyone gets a misunderstandin', that's a pair of eyes)

AccidentalFourierTransform

sure it is

Slereah

$R_{\clubsuit \diamondsuit \heartsuit \spadesuit}$

$\daleth$

0celo7

$\digamma$

Slereah

I didn't know there was letters being beth used for math

0celo7

do people actually use these symbols?

Slereah

21:14

What is daleth in math?

0celo7

probably set theory

alarge

@Slereah I seem to remember Evans' book to be full of these. rsc.anu.edu.au/~evans/evansmorrissbook.php

0celo7

$\Game_{ab}$ is the Einstein tensor

Slereah

No that is clearly the nietsniE tensor

Emilio Pisanty

@0celo7 what the hell is that

Slereah

21:16

It's the nietsniE tensor

Emilio Pisanty

@Slereah that's a great name for a tensor

0celo7

lol

Emilio Pisanty

a.k.a. the 'nothing, never' tensor

0celo7

Maybe I should write a GR book

I will supplant Sachs and Wu as having the shittiest notation

Slereah

$\eth$

what

Why does that $\partial$ have a hairdo

Emilio Pisanty

21:17

@0celo7 there's some anecdote about Serge Lang complaining about notation

and then someone repeatedly using $\displaystyle \frac{\Xi}{\overline{\Xi}}$ in a lecture to annoy him

0celo7

@EmilioPisanty yeah?

@EmilioPisanty lol

Slereah

$\iiiint$

0celo7

@Slereah Hey! I've seen that one used

Petersen uses it in a double complex somewhere

Emilio Pisanty

this done on a blackboard, no less

so no fancy serifs on the xis, either

Slereah

$\leftrightsquigarrow$

weeee

Emilio Pisanty

21:19

I've been unable to trace back that anecdote, though, but I really want to

0celo7

$\lmoustache$

Yes!

Slereah

$\maltese$

Illuminati confirmed

0celo7

$$\bigg\lmoustache_{\mathfrak a}^{\mathfrak b} \mathfrak f(\mathfrak x)\,\mathfrak d\mathfrak x=\mathfrak f(\mathfrak b)-\mathfrak f(\mathfrak a).$$

17th century calculus!

I...really like that integral.

AccidentalFourierTransform

$\newcommand{\mathfrak}{\text{GTFO}}$

Slereah

$\pitchfork$

Diabolical

$\Pr$

What is this

0celo7

21:24

@AccidentalFourierTransform you

AccidentalFourierTransform

Prandtl Number

0celo7

how the hell do you know that?

AccidentalFourierTransform

know what

Emilio Pisanty

@AccidentalFourierTransform $\mathfrak{does\ that\ actually\ work?}$

AccidentalFourierTransform

yep

Emilio Pisanty

21:27

well, whaddaya know

0celo7

it's pretty evil

Emilio Pisanty

$\newcommand{\mathfrak}{\mathsf}$

0celo7

huh

wtf I love mathsf now

Emilio Pisanty

$\newcommand{\mathrm}{\mathfrak}$ $\newcommand{\mathcal}{\mathfrak}$ $\newcommand{\mathscr}{\mathfrak}$

AccidentalFourierTransform

you broke it

0celo7

21:29

error

Emilio Pisanty

@AccidentalFourierTransform did not

this might, though

0celo7

Hmm.

Why is the star board different from the messages?

Emilio Pisanty

$\newcommand{\mathsf}{\mathfrak}$

0celo7

STOP

Emilio Pisanty

YES

$\mathfrak{broke\ it}$

0celo7

21:30

great, my equations in the star board are broken

wtf is wrong with you

Emilio Pisanty

I don't even know how to un-break it

AccidentalFourierTransform

you cant

itll stay like that forever

you happy?

Emilio Pisanty

@AccidentalFourierTransform "forever" is a pretty strong word

Slereah

it will stay that way until it is removed from the scrollback

AccidentalFourierTransform

you were not here the last time we broke the latex, were you?

Emilio Pisanty

21:31

@AccidentalFourierTransform possibly

AccidentalFourierTransform

lots of people from other rooms came here to see what was going on

Emilio Pisanty

can't remember the details though

I remember one time it got pretty messy

AccidentalFourierTransform

Jan 16 at 16:58, by ACuriousMind

Dear lord, what is going on in this chatroom?

0celo7

$\newcommand{\mathfrak}{\mathfrak}$

Hmm

$\newcommand{\mathsf}{\mathsf}$

Emilio Pisanty

@0celo7 how's that going to help?

0celo7

21:33

wtf did you do??/

@EmilioPisanty I have no idea what you did

the only way they can fix it is by deleting this whole thread

Emilio Pisanty

@0celo7 \newcommand{\mathfrak}{\mathsf} concurrent with \newcommand{\mathsf}{\mathfrak}

0celo7

so it's an infinite loop...

Emilio Pisanty

Here it is: $\newcommand{\mathfrak}{\mathsf}$ $\newcommand{\mathsf}{\mathfrak}$ in case someone wants to star that and make things worse

0celo7

dammit

I don't understand this

chat is forever ruined

Emilio Pisanty

@0celo7 "forever" is a strong word

0celo7

21:37

@EmilioPisanty ?? When will it get fixed

ok, it'll be broken until the protons decay

not forever, but close

Emilio Pisanty

@0celo7 it is only broken when the offending loop-causing commands are visible on the screen or through scrolling

0celo7

which is forever

Emilio Pisanty

so the ones above will eventually pass out of the reckoning

that star on the right, though

0celo7

@EmilioPisanty I flagged it. I'll take the ban to save the chat.

Emilio Pisanty

@0celo7 you flagged your own message as offensive?

AccidentalFourierTransform

21:40

can we close this room and start a new one afresh?

0celo7

No, for moderator attention.

Emilio Pisanty

I mean, it's you that broke chat forever ::grin::

@AccidentalFourierTransform is it crucial that we discuss mathfrak further?

0celo7

Well, we can't use mathfrak or mathcal anymore.

@EmilioPisanty No Lie algebras

i guess that's fine by me

Emilio Pisanty

fine by me, too

AccidentalFourierTransform

we love discussing mathfrak

0celo7

21:41

We can still do analysis

now, if you broke $\epsilon$ we'd be in major trouble

AccidentalFourierTransform

its a topic that comes up every now and then

Emilio Pisanty

@0celo7 that's just asking for trouble

AccidentalFourierTransform

$\newcommand{\epsilon}{\varepsilon}$ $\newcommand{\varepsilon}{\epsilon}$

0celo7

$\epsilon$

YOU MONSTER

quiet sobs

$\smalll {\mathscr E}$

Hmm.

\bbig works, why doesn't \ssmall?

oh it's bigg

Ben Niehoff

does LaTeX display in chat for you people? It doesn't for me

0celo7

21:44

n00b

Ben Niehoff

sorry

Emilio Pisanty

$\newcommand{\alpha}{\beta}$ $\newcommand{\beta}{\gamma}$ $\newcommand{\gamma}{\delta}$ $\newcommand{\delta}{\zeta}$ $\newcommand{\zeta}{\eta}$ $\newcommand{\eta}{\theta}$ $\newcommand{\theta}{\iota}$ $\newcommand{\iota}{\kappa}$ $\newcommand{\kappa}{\lambda}$ $\newcommand{\lambda}{\mu}$ $\newcommand{\mu}{\nu}$ $\newcommand{\nu}{\omicron}$ $\newcommand{\omicron}{\pi}$ $\newcommand{\pi}{\rho}$ $\newcommand{\rho}{\sigma}$ $\newcommand{\sigma}{\tau}$

$\alpha$

Ben Niehoff

is there a setting I'm missing or something?

AccidentalFourierTransform

@EmilioPisanty that is a lot of dedication there

0celo7

this is pretty horrible

can we have some mods in here?

@Loong @ACuriousMind @DavidZ @dmckee @Qmechanic Help please

Emilio Pisanty

21:45

$\newcommand{\tau}{\upsilon}$ $\newcommand{\upsilon}{\phi}$ $\newcommand{\phi}{\chi}$ $\newcommand{\chi}{\psi}$ $\newcommand{\psi}{\omega}$

AccidentalFourierTransform

mods are asleep

Emilio Pisanty

aaaaand

AccidentalFourierTransform

quick, post swastikas

Emilio Pisanty

$\newcommand{\omega}{\alpha}$

0celo7

$\alpha$

Emilio Pisanty

21:46

@AccidentalFourierTransform I just wanted to break the entire alphabet there

$\alpha$

0celo7

dear god

dmckee

What. The. Heck?!?

Emilio Pisanty

@dmckee uh. hi

AccidentalFourierTransform

fix this mess please :-(

Ben Niehoff

why stop there? I'd do things like $\newcommand{\alpha}{+}$ or something

dmckee

21:47

@BenNiehoff There is an external script that renders it. All the regular users know it.

AccidentalFourierTransform

we need an adult

Emilio Pisanty

we were just playing around a bit.

dmckee

@BenNiehoff See meta.physics.stackexchange.com/a/5593/520

But right now the regulars are playing games with what is essentially a bug in the way ChatJax works to mess with our heads.

Emilio Pisanty

If mods do want to clean up, and it's possible, I'd appreciate code being placed inside backticks rather than outright deleted =)

Ben Niehoff

yeah, technically \newcommand shouldn't be allowed on any of these

it should be \renewcommand :D

dmckee

21:49

@EmilioPisanty Well, I could go to that much trouble.

Emilio Pisanty

@dmckee not so much mess with people's heads

dmckee

Is anyone actually trying to do some work/learn something in here right now?

Emilio Pisanty

@dmckee not really

dmckee

Then it's too much work for me. But let's not make this game a regular thing.

Emilio Pisanty

Slereah was trying to defend mathfrak A as a reasonable symbol to use

dmckee

21:50

Please.

AccidentalFourierTransform

^

Ben Niehoff

why would it be unreasonable?

Emilio Pisanty

noble effort, but doomed, because it's not a reasonable symbol

Ben Niehoff

to use mathfrak A

Emilio Pisanty

@BenNiehoff because it looks nothing like an A

Ben Niehoff

21:51

sure it does, if you know anything about typeface history :P

Emilio Pisanty

@BenNiehoff yeah, well

Ben Niehoff

mathfrak P is weirder looking

Emilio Pisanty

making the history of typefaces a prerequisite for science is not exactly "lowering the barriers to participation", is it

AccidentalFourierTransform

what if I dont want to lower the barriers to participation?

what if I want just a small elite to participate?

what if I want JD back?

dmckee

@AccidentalFourierTransform You'll have trouble getting NSF funding, of course.

Emilio Pisanty

21:53

@BenNiehoff all of mathfrak AGHIJOPQSTVY should be banned

@dmckee you probably want to say ERC there

Ben Niehoff

lol, I use about half of those ones

AccidentalFourierTransform

@dmckee a small, rich elite

dmckee

Then, you're good to go.

Emilio Pisanty

@BenNiehoff and you think your audience understands your notation?

Ben Niehoff

mathfrak S has a long tradition

Emilio Pisanty

21:54

beyond the level of "Let (squibble #37) be an algebra..."

@BenNiehoff of bewildering audiences worldwide

Ben Niehoff

hey, after you sit through a few blackboard talks where people use lowercase xi and don't even bother to call it xi, but just call it "squiggle" instead...

then you can learn to appreciate a bit of mathfrak

dmckee

@EmilioPisanty I've sat through a lecture on getting NSF funding, but not one on getting ERC funding.

0celo7

We should be raising the barriers @EmilioPisanty

dmckee

The NSF has a nice sheet they hand out.

0celo7

Look at what lowering got us. Vixra.

dmckee

21:55

One side is how to not get your grant funded the fast way.

The other side is how to not get your grant funded the slow way.

Emilio Pisanty

@BenNiehoff "why do people keep using this G thing for s-y objects?"

@dmckee it's hard to get NSF funding in Spain ;-)

dmckee

The first side is stuff the clerical staff will notice and discard without it ever getting to a scientist.

AccidentalFourierTransform

vixra is the pinnacle of elitism

only the best of the best

Ben Niehoff

lol

Emilio Pisanty

@AccidentalFourierTransform ???

dmckee

21:56

@EmilioPisanty Fair enough. I'd probably have a hard time getting ERC funding.

Slereah

Conservapedia is much better than vixra, science-wise

Ben Niehoff

imagine if one had to write something backwards in order for vixra to accept it

it would have the same content!

Slereah

conservapedia.com/Counterexamples_to_Relativity

"Despite wasting millions of taxpayer dollars searching for gravitational waves predicted by the theory, no direct observation of gravity waves has occurred.[19] Sound like global warming? Then, in classic liberal claptrap, the liberal media claimed that gravitational waves were discovered when in fact no such direct observation was made."

Emilio Pisanty

Every time viXra gets bashed, I feel compelled to bring up Phillip Gibbs' defense of it on Quora.

dmckee

@Slereah Wait. When did relativity become something politically charged?

It just is.

Emilio Pisanty

21:58

I think he does bring up arguments that cannot be dismissed easily.

AccidentalFourierTransform

that shit long

I aint reading that

Slereah

@dmckee I knew you were nothing but a bleeding heart liberal!

"The action-at-a-distance by Jesus, described in John 4:46-54, Matthew 15:28, and Matthew 27:51."

"The failure to discover gravitons, despite spending hundreds of millions in taxpayer money in searching. While these tax dollars were not necessarily "wasted", the lack of results indicate that scientists need to revisit their hypothesis."

He brings up tax payer money a lot

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