« first day (1826 days earlier)      last day (3104 days later) » 

9:12 PM
Even cnn keeps it real with their 'skin in the game' phrases
The real question is, is a brane a p-form?
 
@Danu tell me pls
 
@bolbteppa wat? A brane is supposed to be an actual existent object (spatially extended and all)---how would you say that it is a $p$-form?
 
space can also be described by p-forms
 
@Slereah Huh? The p-forms live on space(time), how would they describe it?
 
Well you can define a spacelike slice with the set of tangent 1-forms to it!
 
9:19 PM
"The natural objects, charged under a $(p+1)-$form $A_{p+1}$, are $p-$branes", where does such a statement even come from?
 
@dmckee can this be migrated to chem.SE?:
0
Q: Forster rate dependence on temperature

TanMathIn the Forster rate expression, what values are dependent on temperature?: Forster orientation factor, k^2 the refractive index of the solvent, n The spectral overlap, J the quantum yield of the donor, $\Phi$

 
@bolbteppa A $p+1$-form is naturally suited to be integrated over a $p+1$-dimensional volume to obtain an action for it. A $p$-brane sweeps out a $p+1$-dimensional worldvolume.
 
@JohnDuffield is there any correlation between the 26 dimensions in string theory and letters of the alphabet? Did they just choose 26 for labelling convenience, or was there another reason?
2
(I couldn't help it, sorry)
 
Have you ever wrote an equation so massive that you ran out of indexes
 
No :(
 
9:24 PM
@Slereah Why would I write my equations with indices? :P
 
Let's do it!
Spinor indice is $\psi^A$ and $\bar \psi^{\dot A}$, IIRC
With $\gamma_{A\dot A}^\mu$
 
What does it mean when all beta functions vanish?
 
The gauge field is $A^a_\mu$
 
@Danu Scale invariance, and that means in almost all cases you've got a conformal field theory on your hands
 
@Slereah Note: Sub-labeling is a thing.
 
9:27 PM
The tetrad field and spin connection are $e^m_\mu$ and $\omega^\mu_{mn}$
 
@ACuriousMind That's what I thought (never had any formal training in renormalization but heard enough blabla by now...)
But I'd like a more interesting description for the equation
 
The wavefunction is $\Psi^\Sigma$
 
$$\delta \Bigg\langle \prod_{m}\mathcal{O}_{i_m}(x_m)\Bigg\rangle=
-\epsilon\sum_n \Delta_{i_n}^j \Bigg\langle \mathcal{O}_j(x_n) \prod_{m\neq n} \mathcal{O}_{i_m}(x_m)\Bigg\rangle$$
 
And we will use n for flavor indexes
 
Anything nicer than just "scale invariance"?
where $\delta O$ is exactly what gives rise to the remaining term, btw
 
9:29 PM
So with all that, what would the Schwingeer Dyson equation...
The EOM would be $e^\mu_m \gamma^m_{\dot A A} D_\mu \psi^A_n = 0$
 
@Danu 1. What isn't nice about scale invariance? 2. What has the equation written there to do with beta functions?
 
@ACuriousMind The full equation is:
 
Or $e^\mu_m \gamma^m_{\dot A A} (\partial_\mu \psi^A_n + A^a_\mu \tau_a \psi^A_n + \omega_{\mu A \dot A}\psi^A_n) = 0$
 
Renormalization group equation in disguise?
 
It's horrible notation to make the dependence on $x$ explicit, but then take a derivative w.r.t. $g^i$ :P
 
9:34 PM
@ACuriousMind Not my choice (also note that the fields $\mathcal O$ are not what depends on the $g$'s, it's hidden in the exponential from the expectation value)
 
But then if we do in wavefunction indexes, $\psi$ is an operator, $\psi_{\Sigma \Upsilon}$
 
@Danu Okay, what is $\delta$, anyway? What are you varying?
 
@ACuriousMind $x\mapsto x+\epsilon x$
Scale transformation, unsurprisingly
 
$\bar \Psi^\Upsilon e^\mu_m \gamma^m_{\dot A A} (\partial_\mu \psi^A_{n\Sigma\Upsilon} + A^a_\mu \tau_a \psi^A_{n\Sigma\Upsilon} + \omega_{\mu A \dot A}\psi^A_n) \Psi^\Sigma= 0$
There you go
 
@Slereah please stop
 
9:36 PM
ARE YOU NOT ENTERTAINED
 
I'll say something like: When the $\beta$'s vanish, the only scale dependence of the exp. value comes from the $\mathcal O$'s themselves
i.e. the theory is scale-invariant
 
+4/-2
 
I hate the QFT curriculum at LMU. Nobody bothered to properly plan shit
 
@Danu Uh, no, that's not a scale transformation in the sense one usually uses the term. The "scale invariance" refers to the theory not changing when one changes the renormalization scale.
 
So now I end up having to do this stuff without ever officially having been introduced to beta functions and whatever
@ACuriousMind Okay, well I mean it in the spacetime sense here
(which it is)
@ACuriousMind Also, I'm pretty sure this somehow establishes a connection between the two.
 
9:38 PM
Although
 
As this "renormalization group equation" comes purely from the transformation I wrote down
 
I should add an index for every charge of the spinors
color charge, weak charge and charge charge
 
Stap, pliz, Slereah
nobody wants to see it
 
Indexes are life
 
Indices are
 
9:39 PM
life
 
@Danu Coordinate scaling is $x\mapsto \lambda x$, not the translation $x\mapsto x + \epsilon x$.
 
@ACuriousMind This is the infinitesimal version
 
$\lambda = (1+\epsilon)$
 
^
 
Hm
Thinking about it
 
9:41 PM
where did the emojis go?
 
What emojis
Do you want it with emoji indexes
 
Yes. What's the Seiberg-Witten functional in animal notation?
Question time! What's the best notation for the volume form?
 
@TanMath It's past the time-limit for migration. Sorry.
 
$\bar \Psi^☠ e^🍎_💃 \gamma^💃_{🐮 🐱} (\partial_🍎 \psi^🐱_{🍕👾☠} + A^👪_🍎 \tau_👪 \psi^🐱_{🍕👾☠} + \omega_{🍎 🐱 🐮}\psi^🐱_{🍕👾☠}) \Psi^👾= 0$
There you go
Image version for higher res :p
 
No one wants to tell me what the best notation for the volume form is :(
 
9:49 PM
Isn't it just $\varepsilon$
$\varepsilon_{ijkl}$
 
n dimensions
 
$\varepsilon_{ijk...}$
 
@ACuriousMind notation guru pls
 
Or $d^nx$
 
$\mathrm{vol}_g$?
 
9:54 PM
🍔 < ideal volume form notation
 
@Danu Are the $\mathcal{O}_{i_m}$ arbitrary observables or are they "special"? Also, why is there a free index $j$ on the r.h.s.?
 
@ACuriousMind The index is not free---it is summed over by the Einstein convention (yes, shitty notation to sometimes write sums explicitly and sometimes not, again not my choice)
@ACuriousMind They're observables that transform in this special way
...which I think is just the conformally covariant transformation right
 
Volume form!
 
@Danu No, a conformal transformation wouldn't have the $\beta$s in there
 
@ACuriousMind $\delta O_i(x)=-\epsilon \Delta_i^j O_j (x)$
 
10:01 PM
@Danu Yes
That's the infinitesimal transformation under a dilation for $\Delta$ the weights/scaling dimensions
 
@ACuriousMind I'm pretty sure that resembles the def. I got of covariant thingy
@ACuriousMind Right
:D
Anyways, I think it's not important in this exercise
 
Now that I understand what that equation is, what was the question about it again?
 
Is there any "nicer" meaning to that first equation, other than "scale invariance"
32 mins ago, by Danu
I'll say something like: When the $\beta$'s vanish, the only scale dependence of the exp. value comes from the $\mathcal O$'s themselves
 
@Danu I really don't get why you think scale invariance isn't nice ;P
 
@ACuriousMind dunno
anyways, it's fine
now I just need to yadayada something about beta function of $\mathcal N=4$ SYM vanishing
also, any good books on SUSY?
Particularly, ones that allow me to understand the above in ~5 minutes? :)
 
10:11 PM
holy crap can someone please just tell me what the best notation for the volume form is
 
$\operatorname{vol}$?
or $\omega$
please don't do $\mathrm{d}(\text{anything})$
 
ah!
 
Please do
 
$\mathrm{d}v$
 
That is how real physicists do it
 
10:12 PM
disgusting
 
$d^nx$
 
thanks for the tip!
@Danu no you
@Slereah What is the animal translation of $$\mathrm{SW}[\phi,A]=\int_M\left(|\nabla_A\phi|^2+|F^+_A|^2+\tfrac{1}{2}R|\phi|‌​^2+\tfrac{1}{8}|\phi|^4\right)\,\mathrm{d}v$$
 
>SW
Why W
 
witten!
 
Is Witten so special that he gets a whole new symbol for his action
 
10:15 PM
yup
 
Or do you mean $S_W$
 
no the S is for Seiberg
$S_{\mathrm{SW}}$ works too
 
Also
Shouldn't scalar fields also have an index
After all they are also bundle sections
Of one dimension but still
 
beats me
haven't read that part
 
(I used pizza for the flavor index, btw)
(if you did not notice the joke)
 
10:17 PM
lol
I did not
 
@dmckee oh ok.. I will delete it..
Does nobody here know about FRET?!
 
Free Range Electron Tomography
 
@Slereah Why would that give them an index?
What would it label?
 
particle flavor
 
@Slereah Flavour symmetry is broken and not a gauge symmetry, why would you give stuff an index for that?
 
10:22 PM
Well because flavor is still an index :p
Although there's no implicit summation
You have to put it in by hand
$\sum_🍕$
 
10:37 PM
@ACuriousMind cheddar cheese popcorn is amazing
also what volume form notation is best
 
Sirs, this question; physics.stackexchange.com/questions/216411/… Yes, it has observations from old books in it. The question should be ok, and please shoot down everything in it freely. I will rewrote is as easily as I just did with this one; physics.stackexchange.com/questions/216591/… -But why it needs to be put on "hold". -really?
 
@JokelaTurbine direct that @DavidZ who closed it
we had no input there
 
@DavidZ pls. read my comment.
 
Questions like this one are why I dislike the "mainstream physics" close reason.
The question may be a duplicate, it may be poorly constructed, etc., but it's a reasonable question in its own right and closing it for being "not mainstream" doesn't make any sense.
 
Hey, how difficult would it be to do a preliminary (not scientific accuracy) simulation of maxwell's equations in curved spacetime?
 
10:43 PM
ask chris w
 
In static spacetime. Am I wrong that it would just be en.wikipedia.org/wiki/… + my metric of choice + my integrator of choice? @ChrisWhite
@0celo7 gooood idea.
 
@JokelaTurbine Right off the bat (I haven't read the whole question yet), I might advise condensing it. Three pictures, long paragraphs, and a less-organized-than-in-an-optimal-world structure make for a post that is a bit confusing.
 
@NeuroFuzzy well, who else would possibly know the answer? maybe Jim? he abandoned us
 
@JokelaTurbine Reading that question, I have no idea what 80% of the stuff in it has to do with the question in the title, or the question you actually pose at the end. Why are you talking about Moses and longer lifespan? What do these pictures in there have to do with anything?
 
Yeah thanks for reply. But this is physics, not math. To me it means the we make our hypothesis allways in somekind of real context. In physics we dont masturbate with n-dimensions, we just have the x,y,z, and maybe time and what ever is relevant. I am trying to shood down this stupid idea, which has irritated me for few years, and which I haven't been able to prove wrong.
 
10:48 PM
@JokelaTurbine In addition, the mistaken premise doesn't help. The Sun does not influence Earth's rotation. Given that ~75% of the post is based on that, you may want to fix that misconception. There's nothing wrong with asking a question based on a misunderstanding - I've done that before - but forging ahead after learning that the premise is incorrect isn't a good idea.
 
> In physics we dont masturbate with n-dimensions
 
@ACuriousMind The very model of a scientist salarian!
 
@0celo7 I agree,,,
 
Also, you wrote
> This all seems plausible, but the Question; Would the Atmosphere survive this higher rotation speed? -remains open. I think that the magnetic field would be stronger through the higher rotation speed, and thus solar winds are in control.
 
@JokelaTurbine String theory is done in 26, 10 or 11 dimensions :D
 
10:49 PM
@NeuroFuzzy Had to be me. Someone else might've gotten it wrong.
 
Depending on how much stuff you're doing
 
"This all seems plausible" seemed to tell me that the other stuff was separate and irrelevant . . . and thus unnecessary for the question.
 
@0celo7 It doesnt matter if it's 126, as long as it means something. "n" doesn't.
 
Basically, you need to address David Hammen's comment:
No. The cause of the Earth's rotation is not the Sun. The Earth is rotating because it was rotating when it formed 4.5 billion years ago and because the torques exerted mostly by the Moon are small. The torques exerted by the Sun are much smaller yet. Dinosaurs did not need reduced gravity. Our ancestors did not live almost 1000 years. Your hypothesis has nothing to do with climate 4000 years ago. — David Hammen yesterday
 
I'm confused. Is the Earth 4000, 6000 or 4.5 billion years old?
One of them is such an outlier, it can't possibly be true!
 
10:52 PM
@0celo7 Have someone defined a year exactly?
 
@0celo7 You've gotta be joking.
 
@HDE226868 He is
 
@JokelaTurbine The time it takes light to travel one lightyear.
 
@0celo7 well, you can't have things YOUR way. How about we compromise right in the middle and call it 6,000.
 
@NeuroFuzzy I can live with that.
 
10:53 PM
@ACuriousMind I figured, but you know that split second of doubt that sometimes enters your brain when talking to @0celo7? . . . I had that.
 
@0celo7 have someone defined the distance of lightyear exactly?
To me the 4.5 Billion is the closest correct
 
@JokelaTurbine The distance light travels in one year. Duh!
 
Circular reasoning
 
@0celo7: Stop trolling people who don't know you'Re not serious :P
 
@JokelaTurbine Based on the Earth's current orbital period, of course.
 
10:55 PM
@ACuriousMind then answer my volume form question D:
 
I dont't care if Earth is 1 or 100 Billion years old.
 
why do you refuse??
 
And Earth's orbital period is not constant
 
@0celo7 No, you have to learn to develop your own aesthetic ;)
 
@ACuriousMind dude just tell me what you use, please
 
10:55 PM
@JokelaTurbine Not constant, but pretty darn close.
 
I will decide for myself, but I want suggestions
 
@HDE226868 in your scale, but in 4 billion years?
 
@JokelaTurbine A year is based on the revolution around the sun, not on the rotation around its own axis. The latter defines a day, not a year
So your questions about the non-constancy of the rotation of earth around its own axis have nothing to do with a year
 
@JokelaTurbine When we use "1 year" as a unit, we mean the number of seconds it currently takes Earth to revolve once around the Sun.
 
@ACuriousMind no shit? I thought it was the distance light travels,,,, :-)
 
10:57 PM
I think ACM is trolling me
 
@JokelaTurbine The Earth's orbit is stable in the long-term - and it has been in the same stable state for a long time.
 
@JokelaTurbine For the actual definitions of the precise units we use to make scientific measurements, see the definition of SI units
You'll find no circular reasoning there, and no definitions based on things like orbital periods which might change
 
All trolling everyone,,, Look this joke; youtube.com/watch?v=-9Jp_XCvVto
 
@ACuriousMind wahhhh
 

« first day (1826 days earlier)      last day (3104 days later) »