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8:00 PM
Or something
 
@loltospoon it should be a differential operator
use difference quotients
 
Why use a numerical method
It's one of the simplest system there is
 
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
 
finite elements, baby
 
what do you mean?
 
8:10 PM
@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
 
@AccidentalFourierTransform Who knows
Ask @ACuriousMind
 
hes mad at me
 
why??
 
idk
he not returning my calls or texts
he blocked me on snapchat
and I found out that he's on tinder
 
wow
@ACuriousMind you're sleeping on the couch for a while
 
8:25 PM
Internet does not work aaaaargh
 
I meant my internet connection :-D
 
@AccidentalFourierTransform why don't you do something nice, like analysis
 
bc Im watching a movie right now
 
8:41 PM
what does that have to do with analysis
 
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
 
$\omega$?
 
the first uncountable ordinal?
 
no. $\omega$.
cmon. You can do it.
 
8:44 PM
0
Q: Learning GR: How do I know when to evaluate the metric/Christoffel symbol at a point, and when not to?

Marius JonssonI 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
 
2
Q: Ricci scalar for a diagonal metric tensor

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

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"?

Doug McLellanI 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 ...

@Slereah for you ^
 
>using $\mathcal R$ for the algebra
I shiggy diggy
 
what's wrong with it?
 
The standard is $\mathfrak{A}$
 
8:55 PM
why?
 
Anyone understand this?
0
Q: How to determine light intensity at each frequency in black-body radiation?

wld.qtrI 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 ...

 
It stands for "$\mathfrak A$lgebra"
$\mathfrak{Algebra}$
 
oh, is that an A
$\mathfrak A$
 
yes
 
@Slereah That's the least helpful mathfrak character ever
 
8:57 PM
$\mathfrak U$
 
It stands for "I bet yo$\mathfrak A$ can't guess what this character actually is"
 
It's pretty helpful if you want to write an algebra
 
why not $\mathscr A$ like most people?
or $\mathcal A$ like plebs
 
↑ that
↑↑ and that
 
I dunno
Some people seem to like fraktur
 
8:59 PM
I said happy birthday to ACM in fraktur
I bet you can't read it
 
@Slereah most characters are OK
 
Lower case fraktur is nice
 
most lowercase is ok, except for $\mathfrak{k,w,x,y}$
 
Is that $\mathfrak n$?
Hah
wtf is that
$\mathfrak w$
^I've seen that one used somewhere
$\mathfrak t$
$\mathfrak k$
 
I've seen old russian math papers
They use a lot of fraktur
 
9:01 PM
mathfrak k is stupid
$\mathfrak{abcdefghijklmnopqrstuvwxyz}$
 
Rocky $\mathfrak w$
 
x and y??? @EmilioPisanty why???
 
Uppercase, any of $\mathfrak{AGHIJOPQSTVY}$ is trouble
@0celo7 $\mathfrak x$ vaguely makes it
 
@EmilioPisanty the third one is an H
 
there's no excuse for $\mathfrak y$
 
9:02 PM
it's a German eta, clearly
 
What libraries does mathjax have, anyway
 
@Slereah who knows
why?
 
wondering what symbols I can make
 
oh, no idea
 
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
 
9:06 PM
$\amalg$
Weren't you looking for this
 
I figured it out
\amalg
 
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
 
$\cal{ABC}\mathcal{ABC}$
 
I want a mathfrak ß just to mess with people
 
cal and mathcal seems identical
 
9:09 PM
what could one use $\bigwedge$ for
 
@0celo7 Repetition of logical conjunction
ACuriousMind is $\cancel{\text{a wiener}}$ great
 
$\checkmark$
Aha!
Yes!
 
@0celo7 $\bigwedge_{i=1}^n P_i = P_1\wedge \cdots\wedge P_n$
 
Hm, didn't work
 
@EmilioPisanty why would you ever use such notation though
 
9:11 PM
in case you are doing logic
for instance
if you are using the Craig axiomatization scheme
 
$\bigwedge$ that
 
$\checkmark_{\mu\nu\rho\sigma}$
This is the new notation for Riemann tensors
 
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
 
$\ominus,\oplus$
 
also $\odot$
 
9:12 PM
are those circles the same?
 
$\Cap$ Take a look, it's in a book, a reading rainbow $\Cap$
 
$\bigodot$
 
sniper dot?
 
$\bigodot\bigodot$
 
yeah what's the double intersection thing?
compact intersection?
@EmilioPisanty Tits! (The mathematician, of course.)
 
9:13 PM
(before anyone gets a misunderstandin', that's a pair of eyes)
 
$R_{\clubsuit \diamondsuit \heartsuit \spadesuit}$
$\daleth$
 
$\digamma$
 
I didn't know there was letters being beth used for math
 
do people actually use these symbols?
 
9:14 PM
What is daleth in math?
 
probably set theory
 
@Slereah I seem to remember Evans' book to be full of these. rsc.anu.edu.au/~evans/evansmorrissbook.php
 
$\Game_{ab}$ is the Einstein tensor
 
No that is clearly the nietsniE tensor
 
@0celo7 what the hell is that
 
9:16 PM
It's the nietsniE tensor
 
@Slereah that's a great name for a tensor
 
lol
 
a.k.a. the 'nothing, never' tensor
 
Maybe I should write a GR book
I will supplant Sachs and Wu as having the shittiest notation
 
$\eth$
what
Why does that $\partial$ have a hairdo
 
9:17 PM
@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
 
@EmilioPisanty yeah?
@EmilioPisanty lol
 
$\iiiint$
 
@Slereah Hey! I've seen that one used
Petersen uses it in a double complex somewhere
 
this done on a blackboard, no less
so no fancy serifs on the xis, either
 
$\leftrightsquigarrow$
weeee
 
9:19 PM
I've been unable to trace back that anecdote, though, but I really want to
 
$\lmoustache$
Yes!
 
$\maltese$
Illuminati confirmed
 
$$\bigg\lmoustache_{\mathfrak a}^{\mathfrak b} \mathfrak f(\mathfrak x)\,\mathfrak d\mathfrak x=\mathfrak f(\mathfrak b)-\mathfrak f(\mathfrak a).$$
17th century calculus!
I...really like that integral.
 
$\newcommand{\mathfrak}{\text{GTFO}}$
 
$\pitchfork$
Diabolical
$\Pr$
What is this
 
9:24 PM
@AccidentalFourierTransform you
 
Prandtl Number
 
how the hell do you know that?
 
@AccidentalFourierTransform $\mathfrak{does\ that\ actually\ work?}$
 
9:27 PM
well, whaddaya know
 
it's pretty evil
 
$\newcommand{\mathfrak}{\mathsf}$
 
huh
wtf I love mathsf now
 
$\newcommand{\mathrm}{\mathfrak}$ $\newcommand{\mathcal}{\mathfrak}$ $\newcommand{\mathscr}{\mathfrak}$
 
9:29 PM
error
 
@AccidentalFourierTransform did not
this might, though
 
Hmm.
Why is the star board different from the messages?
 
$\newcommand{\mathsf}{\mathfrak}$
 
STOP
 
YES
$\mathfrak{broke\ it}$
 
9:30 PM
great, my equations in the star board are broken
wtf is wrong with you
 
I don't even know how to un-break it
 
you cant
itll stay like that forever
you happy?
 
@AccidentalFourierTransform "forever" is a pretty strong word
 
it will stay that way until it is removed from the scrollback
 
you were not here the last time we broke the latex, were you?
 
9:31 PM
@AccidentalFourierTransform possibly
 
lots of people from other rooms came here to see what was going on
 
can't remember the details though
I remember one time it got pretty messy
 
Jan 16 at 16:58, by ACuriousMind
Dear lord, what is going on in this chatroom?
 
$\newcommand{\mathfrak}{\mathfrak}$
Hmm
$\newcommand{\mathsf}{\mathsf}$
 
@0celo7 how's that going to help?
 
9:33 PM
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
 
@0celo7 \newcommand{\mathfrak}{\mathsf} concurrent with \newcommand{\mathsf}{\mathfrak}
 
so it's an infinite loop...
 
Here it is: $\newcommand{\mathfrak}{\mathsf}$ $\newcommand{\mathsf}{\mathfrak}$ in case someone wants to star that and make things worse
 
dammit
I don't understand this
chat is forever ruined
 
@0celo7 "forever" is a strong word
 
9:37 PM
@EmilioPisanty ?? When will it get fixed
ok, it'll be broken until the protons decay
not forever, but close
 
@0celo7 it is only broken when the offending loop-causing commands are visible on the screen or through scrolling
 
which is forever
 
so the ones above will eventually pass out of the reckoning
that star on the right, though
 
@EmilioPisanty I flagged it. I'll take the ban to save the chat.
 
@0celo7 you flagged your own message as offensive?
 
9:40 PM
can we close this room and start a new one afresh?
 
No, for moderator attention.
 
I mean, it's you that broke chat forever ::grin::
@AccidentalFourierTransform is it crucial that we discuss mathfrak further?
 
Well, we can't use mathfrak or mathcal anymore.
@EmilioPisanty No Lie algebras
i guess that's fine by me
 
fine by me, too
 
we love discussing mathfrak
 
9:41 PM
We can still do analysis
now, if you broke $\epsilon$ we'd be in major trouble
 
its a topic that comes up every now and then
 
@0celo7 that's just asking for trouble
 
$\newcommand{\epsilon}{\varepsilon}$ $\newcommand{\varepsilon}{\epsilon}$
 
$\epsilon$
YOU MONSTER
quiet sobs
$\smalll {\mathscr E}$
Hmm.
\bbig works, why doesn't \ssmall?
oh it's bigg
 
does LaTeX display in chat for you people? It doesn't for me
 
9:44 PM
n00b
 
sorry
 
$\newcommand{\alpha}{\beta}$ $\newcommand{\beta}{\gamma}$ $\newcommand{\gamma}{\delta}$ $\newcommand{\delta}{\zeta}$ $\newcommand{\zeta}{\eta}$ $\newcommand{\eta}{\theta}$ $\newcommand{\theta}{\iota}$ $\newcommand{\iota}{\kappa}$ $\newcommand{\kappa}{\lambda}$ $\newcommand{\lambda}{\mu}$ $\newcommand{\mu}{\nu}$ $\newcommand{\nu}{\omicron}$ $\newcommand{\omicron}{\pi}$ $\newcommand{\pi}{\rho}$ $\newcommand{\rho}{\sigma}$ $\newcommand{\sigma}{\tau}$
$\alpha$
 
is there a setting I'm missing or something?
 
@EmilioPisanty that is a lot of dedication there
 
this is pretty horrible
can we have some mods in here?
@Loong @ACuriousMind @DavidZ @dmckee @Qmechanic Help please
 
9:45 PM
$\newcommand{\tau}{\upsilon}$ $\newcommand{\upsilon}{\phi}$ $\newcommand{\phi}{\chi}$ $\newcommand{\chi}{\psi}$ $\newcommand{\psi}{\omega}$
 
mods are asleep
 
aaaaand
 
quick, post swastikas
 
$\newcommand{\omega}{\alpha}$
 
$\alpha$
 
9:46 PM
@AccidentalFourierTransform I just wanted to break the entire alphabet there
$\alpha$
 
dear god
 
What. The. Heck?!?
 
@dmckee uh. hi
 
fix this mess please :-(
 
why stop there? I'd do things like $\newcommand{\alpha}{+}$ or something
 
9:47 PM
@BenNiehoff There is an external script that renders it. All the regular users know it.
 
we need an adult
 
we were just playing around a bit.
 
But right now the regulars are playing games with what is essentially a bug in the way ChatJax works to mess with our heads.
 
If mods do want to clean up, and it's possible, I'd appreciate code being placed inside backticks rather than outright deleted =)
 
yeah, technically \newcommand shouldn't be allowed on any of these
it should be \renewcommand :D
 
9:49 PM
@EmilioPisanty Well, I could go to that much trouble.
 
@dmckee not so much mess with people's heads
 
Is anyone actually trying to do some work/learn something in here right now?
 
@dmckee not really
 
Then it's too much work for me. But let's not make this game a regular thing.
 
Slereah was trying to defend mathfrak A as a reasonable symbol to use
 
9:50 PM
Please.
 
why would it be unreasonable?
 
noble effort, but doomed, because it's not a reasonable symbol
 
to use mathfrak A
 
@BenNiehoff because it looks nothing like an A
 
9:51 PM
sure it does, if you know anything about typeface history :P
 
@BenNiehoff yeah, well
 
mathfrak P is weirder looking
 
making the history of typefaces a prerequisite for science is not exactly "lowering the barriers to participation", is it
 
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?
 
@AccidentalFourierTransform You'll have trouble getting NSF funding, of course.
 
9:53 PM
@BenNiehoff all of mathfrak AGHIJOPQSTVY should be banned
@dmckee you probably want to say ERC there
 
lol, I use about half of those ones
 
@dmckee a small, rich elite
 
Then, you're good to go.
 
@BenNiehoff and you think your audience understands your notation?
 
mathfrak S has a long tradition
 
9:54 PM
beyond the level of "Let (squibble #37) be an algebra..."
@BenNiehoff of bewildering audiences worldwide
 
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
 
@EmilioPisanty I've sat through a lecture on getting NSF funding, but not one on getting ERC funding.
 
We should be raising the barriers @EmilioPisanty
 
The NSF has a nice sheet they hand out.
 
Look at what lowering got us. Vixra.
 
9:55 PM
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.
 
@BenNiehoff "why do people keep using this G thing for s-y objects?"
@dmckee it's hard to get NSF funding in Spain ;-)
 
The first side is stuff the clerical staff will notice and discard without it ever getting to a scientist.
 
vixra is the pinnacle of elitism
only the best of the best
 
lol
 
@AccidentalFourierTransform ???
 
9:56 PM
@EmilioPisanty Fair enough. I'd probably have a hard time getting ERC funding.
 
Conservapedia is much better than vixra, science-wise
 
imagine if one had to write something backwards in order for vixra to accept it
it would have the same content!
 
"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."
 
Every time viXra gets bashed, I feel compelled to bring up Phillip Gibbs' defense of it on Quora.
 
@Slereah Wait. When did relativity become something politically charged?
It just is.
 
9:58 PM
I think he does bring up arguments that cannot be dismissed easily.
 
that shit long
I aint reading that
 
@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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