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12:01 AM
I love how my ODE book says that no real life problem will ever work out as nicely as an example in the book
 
Just heard a really bad pun for use any time I'm talking about euler lagrange or extremal paths
"physics is where the action is". Apparently it's in one of Zee's books
 
I'm going to extremize your mum
can confirm
it's in Einstein gravity, that's for sure
 
@0celo7 Well everyone's already maximizing their act- huh...
:/
 
uh.
not always
you can have a minimum or a saddle
 
hehehehe
speak for myself*
 
12:10 AM
or you can be a free spirit and be like "f the mass shell"
@ACuriousMind what if a virtual particle doesn't get back on the mass shell
what if like something happens and interrupts it
 
I think Feynman's demon comes along and gives it a push so it makes it to the shell.
 
hmm
what about strings
what if an off-shell string just tunnels out of the Feynman diagram
D:
or what if a D-brane just shows up and prevents the strings from reuniting
on a scale from 1 to 10, how much sense does any of that make
@obe you have to have questions
@obe something you should know: determine the spin states a system of one spin 1/2 and one spin 1 particle can be in
@obe explain the difference between bosons and fermions
explain the relationship between angular momentum, the rotation group and $\mathrm{SU}(2)$
@obe explain why the norm has to be positive
 
Anyone else here a fan of Ludovico Einaudi?
 
@obe do you know the Heisenberg equation
 
I am rocking Andare. That song is awesome
 
12:24 AM
@obe you should know how to determine the spectrum of the SHO algebraically
 
random Feynman diagram
that's not even the real Boltzmann equation
you need to do it like Straumann
in terms of distributions on the cotangent bundle
 
greetings
 
can you please do my homework
 
I have to do mine :(
 
12:31 AM
will mod Skyrim in return
 
hmm
attractive offer
what HW is it anyways?
 
ODEs of the form $P\mathrm{d}x+Q\mathrm{d}y=0$
like 10 of them
 
ew fuck that
 
::goes to Wolfram::
 
attaboy
Bentley beard
that's a badass name
 
12:36 AM
this one is not even doable
why does it have a solution
 
0celo7 you're breaking my heart
shaking my confidence daily
 
why
because I'm not good at math?
I've been saying this for the past year
idk which one of you clowns thought I was ever smart
 
no because you should be doing GR instead!
 
wtf
I'm done with GR
GR does not pertain to my research
although I'm not sure what does pertain
I need to learn about crystals and shit
I'm going to donate my GR books
 
you don't mean that!
 
12:47 AM
which part
it's not all true
 
any of it
 
it's not all a lie
2 mins ago, by 0celo7
GR does not pertain to my research
if I wanted to do GR research, I'd not be an engineer
3 mins ago, by 0celo7
I need to learn about crystals and shit
this is true
I need to learn some solid state physics
at least for the time being until I can impress the fusion guys
 
I refuse to get rid of my string theory books
String Theory: An Introduction for Engineers and Others Who Can't Into Group Theory will be written some day
 
haha
I want to know enough string theory to understand the Strominger/Vaffa paper
 
12:52 AM
read my book then
it will start from engineering first principles
i.e. beams bend when you put a load on them
and $dy=f'(x)dx$
I will dedicate it to ACM
 
@0celo7 What the hell is an "off-shell string"?
 
"to the man who made my sock nightmares a thing"
 
@0celo7 Ah. Hm. The tunnel string 1, the D-brane not sure
 
someone please integrate $x/(1-x)$
 
$\int \frac{x}{1-x}\mathrm{d}x$.
 
12:55 AM
the integral exists
good enough
or assume $x \ll 1$ and expand
also good enough
 
@0celo7 You keep coming back to my socks.
 
@ACuriousMind "to the man who could never stop mocking me"
 
Not sure what that should tell me
 
although that could be @Danu too
 
lol
Too slow
 
12:57 AM
nah
I took that back because I won't be in HD when you are
@ACuriousMind uh, a string that is off shell
idk what more you want
 
But...what is the shell?
Is it one of these damn blue shells?
 
no
idiot
$p^2=m^2$
it's like you don't even know SR
 
@0celo7 Because mass is a property strings have, apparently?
 
@ACuriousMind well how do you explain massive particles then
these theorists...
 
these string engineers...
 
1:00 AM
whoa
I want that title
although that makes me sound like a piano tuner
nvm
you theorists and your "gluon soup" and your "higgs mechanism"
whatever happened to good ol $m:=F/a$
 
piano tuners are probably a more important part of society than me ;(
...or is it "than I"?
 
no
"than I am"
 
I need the auxiliary verb there?
 
if you want to say I
but what do I know
 
"than I" is fine
 
1:03 AM
@FenderLesPaul decide
 
you don't need "am"
 
no that sounds weird
just "me" is best
 
"piano tuners be more dope than I is"
 
you nutsos
 
nachos
 
1:04 AM
@0celo7 But I think it is gramatically wrong - the "piano tuners" are the subject, but "me" can't be a subject, and the case following the "than" should be the same as the thing "than" is comparing to.
 
oh shut up
 
Mhhhh, nachos
 
help me with this ODE
help with this ODE, or read page 211 ff. in BBS
 
I think ODE is a politically incorrect term
check your DE privilege
 
I keep reading that as the German word Ode
 
1:05 AM
what does that mean again
 
It's...a kind of song
Like a...hymn?
 
or an ode?
 
Yeah, I think hymn captures it
 
lol
you know "ode the song" is English as well
 
Oh
I did not know that
 
1:06 AM
ode to joy
Lang wants to get all the Germans on campus together for a Stammtisch
he's really homesick, poor guy
 
Or he wants an excuse to import lots of German beer :D
 
no, he told me he's homesick
he hates American (food) proportions
 
what!
he hates freedom!
 
he's scrawny like ACM
doesn't have a beard tho
also he dresses nice
ACM seems to have left
it's only 3 AM for him...he must be sick
 
1:41 AM
@DanielSank I think I figured out what was really vexing me on this.
Differential forms are usually defined/studied before the introduction of the metric
(or at least, they are in most books i've been through)
 
they don't need a metric
 
but during integration of differential forms, regardless of the metric
 
the metric is not needed there either
 
you're still using a lebesgue measure
 
you can do everything in terms of a pullback onto R^n
you people and your analysis
 
1:43 AM
which, en.wikipedia.org/wiki/Lebesgue_measure describes as "the standard way of assigning a measure to subsets of n-dimensional Euclidean space"
and is described in the book as, "defined by pulling it back to Euclidean space"
 
did I not just say that
 
("the book" meaning Renteln manifolds tensors forms pg 160)
@0celo7 :P "euclidean" usually refers to the metric too though
 
the metric on Euclidean space is assumed I think
because you need a topology to define the integral on Euclidean space
 
so i was thinking, "How can I do this indepent of euclidean space, so that I have the intuition for spacetime/whatever"
 
and this topology is usually taken to be that of the metric
 
1:45 AM
Yeah, you're totally right
I was trying to think of it in a way that just couldn't work :p
 
you need a topology to do a partition of unity
I think
 
and more importantly you 'need' the "euclidean" lebesgue measure to do the integrals in the first place
 
I dunno about that
analysis is too hard
 
Well I mean, you just use the same euclidean notion of volume/whatever
when you're looking at a parallelipiped that's just a regular euclidean thingy
 
I know what you mean
so what about spacetime
 
1:50 AM
are you asking how integrals are defined on a curved manifold?
 
@0celo7 oh i want to have a nice understanding of $F$ and $dF=0$ and $d \howDoYouLatexStar F=0$
 
all you do for spacetime integrals is pick the volume form $\sqrt{-\operatorname{det}g}\mathrm{d}x^0\wedge\cdots\wedge \mathrm{d}x^3$
 
$\star$
 
@FenderLesPaul no, i'm done asking things, I was just referring to something earlier
 
\star
or *
 
1:50 AM
@NeuroFuzzy ah ok
 
'cause I figured it out! Yay!
 
@NeuroFuzzy what about curvature of abelian principal bundles?
 
@0celo7 i know what six of those words mean
 
@NeuroFuzzy you know that $\mathrm{U}(1)$ is an abelian group
you know that Maxwell is a $\mathrm{U}(1)$ Yang-Mills theory
you know that a $G$ Yang-Mills theory is a theory of the curvature of a $G$-bundle
ok for real this time
this ODE cannot be solved
 
1:58 AM
@0celo7 Okay... things are snapping together... I think i have to look up a better reference for a gauge theory
 
@NeuroFuzzy how much differential geometry do you know
 
this book has one problem on it. "We define a gauge field theory to be a vector bundle over a smooth manifold m, where V is a vector space carrying a representation of a Lie group G"
 
do you know about connections on the tangent bundle?
 
I'm just pounding through curvature and connections and christoffels and stuff, yeah
 

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