The h Bar

AccidentalFourierTransform

6:00 PM

chrome is trolling me or something

it wants me to actually post it here

the url is not working for some reason

Emilio Pisanty

@AccidentalFourierTransform double click on the 430 in the chat message

there's probably a zero-width joiner in there

AccidentalFourierTransform

whatever

Emilio Pisanty

yup

Constantine Black

@ACuriousMind But, indeed, I do not need all the mathematics of homogeneous spaces. I need the relevance of quotient spaces with the subject of EFT and maybe something about equivalence classes... again, Leutwler- arxiv.org/abs/hep-ph/9406283

Emilio Pisanty

AccidentalFourierTransform

6:03 PM

screw it

Emilio Pisanty

=P

AccidentalFourierTransform

its not even that good of a meme

Emilio Pisanty

@AccidentalFourierTransform I agree with that

Constantine Black

@AccidentalFourierTransform Do you have anything in mind?

AccidentalFourierTransform

I mean, its a classic

@ConstantineBlack memes-wise?

Emilio Pisanty

6:03 PM

@AccidentalFourierTransform is it really, though?

AccidentalFourierTransform

kind of

Constantine Black

SSB mathematics- wise :)

AccidentalFourierTransform

nah I hate SSB

so messy

I never learnt it properly

I wouldn't know where to learn it properly anyway

Emilio Pisanty

@AccidentalFourierTransform I'm going to hack into SE and insert zero-width joiners into 10% of all the links you've ever posted =P

AccidentalFourierTransform

Weinberg II perhaps

@EmilioPisanty ಠ_ಠ

Emilio Pisanty

6:05 PM

turn them into invisible 404s

AccidentalFourierTransform

it would be so frustrating, not being able to share my memes

Emilio Pisanty

and that is probably what I get for harping on and on about unicode

AccidentalFourierTransform

your colours are wrong

the grey messages should be green and viceversa

your broke that too

smh

Emilio Pisanty

@AccidentalFourierTransform yeah, I hacked SE earlier just to do that

AccidentalFourierTransform

so you are one of those hackers known as the 4chan?

Emilio Pisanty

6:07 PM

which is why it'll be easy to 404 all the links you ever posted

no, wait, 10%

so it'll be more frustrating to clean up

ACuriousMind

@ConstantineBlack Looking at the passage you are talking about, could it be that you are looking for some basic group theory?

Because that reasoning doesn't really make use of any more advanced mathematics than the very definition of a quotient group and a representation.

Emilio Pisanty

ooooh, btw, now that we have core chat quorum

happy new paper dance

4

AccidentalFourierTransform

there is a typo on the second page

im not telling you where

Emilio Pisanty

@AccidentalFourierTransform is it a spurious zero-width joiner?

AccidentalFourierTransform

no, it's a big typo

Balarka Sen

6:16 PM

@Accidental There is a disgusting S&M joke on the internet somewhere. I am not telling you where.

2

AccidentalFourierTransform

it changes the meaning of the phrase to nazi propaganda

Emilio Pisanty

@AccidentalFourierTransform ah, gotcha

AccidentalFourierTransform

congrats btw

Emilio Pisanty

@AccidentalFourierTransform thanks =)

AccidentalFourierTransform

a couple of months ago I uploaded my masters thesis to the arxiv and for weeks I got mails from random people telling me about their papers -- which were supposedly relevant but not really -- and suggesting me to cite them in future revisions

it was like wtf

its not like Im going to send the thesis to a journal

0ßelö7

6:19 PM

@ACuriousMind

56 mins ago, by 0ßelö7

@yuggib I have a real Hilb sp. $\mathscr H$ and $H\ge 0$ is self-adjoint. I define $H^{1/2}$ using the functional calculus. Given $u\in D(H^{1/2})$ I want a sequence $(u_n)\subset D(H)$ such that $u_n \to u$ and $$\langle H^{1/2}u_n,H^{1/2}u_n\rangle\to \langle H^{1/2}u,H^{1/2}u\rangle.$$ This supposedly follows from "the spectral theorem" but I don't see what they mean

AccidentalFourierTransform

what would an arxiv cite be useful for?

Emilio Pisanty

@AccidentalFourierTransform google-scholar citation counts

AccidentalFourierTransform

does it?

huh

Emilio Pisanty

yeah

AccidentalFourierTransform

and is that kind of self-publicity considered normal? or even ethical?

Emilio Pisanty

6:21 PM

one of the reasons they tend to be higher than scopus or web of science

@AccidentalFourierTransform probably depends on the field

I've yet to be contacted over a preprint on arXiv

of any sort

but then my field doesn't do arXiv all that much

AccidentalFourierTransform

well, high energy physics does

Constantine Black

@ACuriousMind I won't argue with that. But maybe my problem is on understanding the relevance of the quotient space with the pions or how do I reach the conclusion that the mapping f fixes the transformation properties uniquely or, under another phrasing why all the above give us the standard action of G on G/H. Any suggestions on reading or how these things are incorporated in the entire project?

Emilio Pisanty

@AccidentalFourierTransform you submitted to hep-th?

AccidentalFourierTransform

yeah

Emilio Pisanty

yeah, that'll probably get a much closer scrutiny

AccidentalFourierTransform

6:23 PM

it feels weird anyway -- would you email someone to recommend them to read your papers, which may or may not be relevant to their work?

or even suggest them to cite them?

I didnt like it

I would never do that

Emilio Pisanty

@AccidentalFourierTransform that's what you say now

AccidentalFourierTransform

but then again, I would never publicise my work

and, as I learnt recently, I most definitely should

Emilio Pisanty

@AccidentalFourierTransform yeah. One of the toughest lessons to learn.

AccidentalFourierTransform

> The second regret is that I never gave a talk about the result: my shyness speaking about my work still lingered (I think that I rarely felt that my work was important enough). I was at a string meeting in downtown Santa Barbara around that time, and did not ask to speak.
When I told Michael Green about the result, he said I should have spoken. Indeed, the paper has received over 400 citations. But, like quite a few of my papers from that period (including the two with Jim and Jun), it got rather few at first, but then exploded after the second superstring revolution. Perhaps if I had bee…

Emilio Pisanty

@AccidentalFourierTransform do you work on BMS?

whatever that is

AccidentalFourierTransform

6:27 PM

from Polchinski's memories

@EmilioPisanty ?

Emilio Pisanty

@AccidentalFourierTransform as in, is your thesis on nonrelativistic BMS theories?

AccidentalFourierTransform

urbandictionary.com/define.php?term=BMS

@EmilioPisanty I dont even know what that is lol

Emilio Pisanty

@AccidentalFourierTransform hmmmmm. or so you say

AccidentalFourierTransform

you found a thesis about that on the arxiv?

ACM already found out what my real name is

Emilio Pisanty

@AccidentalFourierTransform yes

AccidentalFourierTransform

6:29 PM

Im the author of that Dirac delta paper

let me find it

Mar 16 at 18:30, by ACuriousMind

@AccidentalFourierTransform Suuuure, you don't remember. I'm on to you, Mr Morales!

Constantine Black

@ACuriousMind So maybe to put it differently, where should I read about the entire use of quotient space in the context of ChPT or how we reach to the natural conclusion that this mapping fixes the transformation of the pions and that this mapping is simultaneously related to the quotient space and it' s geometry. Or did you have something else in mind when you mentioned EFT?

Emilio Pisanty

@AccidentalFourierTransform which Dirac delta paper?

AccidentalFourierTransform

arxiv.org/abs/1507.04348

is it stupid or is it genius

I really dont know

Emilio Pisanty

@AccidentalFourierTransform I find the claim dubious

AccidentalFourierTransform

why

Emilio Pisanty

6:39 PM

@AccidentalFourierTransform 'cause none of those people look like they would leave cushy positions in UCLA to do a master's degree in Barcelona

AccidentalFourierTransform

Emilio Pisanty

:39856203 indeed I don't

but given your comments on thesises above, I'm putting my money here

in which case

AccidentalFourierTransform

perhaps I made the Barcelona thing up

Emilio Pisanty

green links? seriously?

AccidentalFourierTransform

wut

oh, the references

oh yes that's me

Emilio Pisanty

6:42 PM

@AccidentalFourierTransform ¯\ _(ツ)_/¯

AccidentalFourierTransform

$$\int_{-\infty}^\infty f(x)\,\mathrm dx=2\pi\delta(i\partial_\epsilon)f(\epsilon)$$

oh boy

Emilio Pisanty

god that's horrifying

AccidentalFourierTransform

it's science

it's art

it's everything

ACuriousMind

@ConstantineBlack I don't have a particular reference in mind because I'm not sure what exactly you're lacking to understand the argument. The paper is saying that there is some (non-linear!) transformation of the pion field under the symmetry $\pi \mapsto f(g,\pi)$ under an element $g\in G$ that obeys the group composition law $f(g_1,f(g_2,\pi)) = f(g_1g_2,\pi)$.

Since the symmetry $H\subset G$ is unbroken, we must have that $f(h,\pi) = \pi$ for all $h\in H$. So if $g_2 = g_1 h$, then $f(g_2,\pi) = f(g_1h,\pi)$. By definition, functions that only care about elements in $G$ "up to $H$" in this manner are functions on $G/H$, so $f$ is a function on $G/H$, and $gH\mapsto f(g,0)$ is an invertible mapping of $G/H$ onto the space in which $\pi$ takes values.

Emilio Pisanty

what's $f(\epsilon)$? at least tell me that it's been fourier-transformed or something

ACuriousMind

6:44 PM

If every point of that space is reachable by a transformation of $0$ (hidden assumption, originates from the $\pi$ being perturbations about the vacuum that corresponds to $\pi = 0$), then this means that space actually is $G/H$.

Emilio Pisanty

@ACuriousMind thoughts on the arXiv link just below the latest image?

ACuriousMind

@EmilioPisanty What sort of thoughts? Should I read it?

Emilio Pisanty

@ACuriousMind regarding authorship, cf. the preceding conversation

AccidentalFourierTransform

@ACuriousMind you've read it already

we discussed it long ago

ACuriousMind

@EmilioPisanty It could well be AFT

Emilio Pisanty

6:50 PM

@ACuriousMind fair enough

mostly, it's just to continue using 'they' but feel less bad if I slip

ACuriousMind

@AccidentalFourierTransform I have?

My mind must be slipping

AccidentalFourierTransform

I meant arxiv.org/abs/1507.04348

ACuriousMind

@EmilioPisanty Major supporting evidence:

Feb 3 at 18:07, by AccidentalFourierTransform

@vzn hi. To be honest, Im not really sure what my thesis is about :-P something about the symmetries of asymptotically flat spaces (BMS symmetry). Right now, all Im doing is playing around with the spherical harmonics in 4d

AccidentalFourierTransform

DELET THIS

:-P

Emilio Pisanty

@ACuriousMind yeah, that's pretty much a deal sealer

AccidentalFourierTransform

6:53 PM

SHHHH

Emilio Pisanty

25 mins ago, by AccidentalFourierTransform

@EmilioPisanty I dont even know what that is lol

lolz

AccidentalFourierTransform

😂😂

now, be a good moderator and delete those messages, will you?

everything, DELETE EVERYTHING

ACuriousMind

@AccidentalFourierTransform Why? It's all public information.

AccidentalFourierTransform

it contains sensitive information

its your responsability

also, because we are friends

Emilio Pisanty

@AccidentalFourierTransform none of it'll come up in searches

and no one'll come looking

skullpatrol

6:56 PM

::takes screenshot::

Emilio Pisanty

we can just bury it in memes and no one will be the wiser

apart from skullpatrol, of course

skullpatrol

};-)

AccidentalFourierTransform

but you never know

Balarka Sen

we can incorporate the sensitive information in the memes

Emilio Pisanty

just ramp up the memes

Balarka Sen

6:57 PM

then it'll never die da ba dee da ba die

skullpatrol

:'(

AccidentalFourierTransform

I request for the witness protection programme

skullpatrol

Request denied

AccidentalFourierTransform

@ACuriousMind just delete two or three, the important ones

I fear for my life

you wouldnt understand it

skullpatrol

He deleted "skullpatrol is fine"?

Emilio Pisanty

7:00 PM

wow, I'm impressed

all that trouble to ZWJ-up that url, and imgur just says "meh"?

huh

Sid

@EmilioPisanty thug life, right there

Emilio Pisanty

@Sid I was trying to insert a zero-width joiner into that url so it would look valid but flop when machine inspected

but apparently imgur is too clever for me

and/or the SE chat engine

lılostafa

@AccidentalFourierTransform me too. I've almost found ACM too (not sure though)

AccidentalFourierTransform

oh no now Mostafa knows too

Emilio Pisanty

@lılostafa I found ACM out at some point but the answer was relatively boring and I forgot

I'll probably forget AFT at some point, too

lılostafa

7:11 PM

@EmilioPisanty gonna spot ACM soon ▄︻̷̿┻̿═━一

Anonymous

@AccidentalFourierTransform I found you on Twitter

Anonymous

Lemme follow you :P

AccidentalFourierTransform

PLEASE STOP

Sid

@Blue You are stalking people?! :o

skullpatrol

wut?

Anonymous

7:12 PM

@Sid Of course ;)

lılostafa

@Sid stalking is the only real use of social media like FB and Instagram as far as I know

Sid

@lılostafa I don't disagree with that

Anonymous

Meh. His profile is pretty boring

Anonymous

:'P

Anonymous

I thought it would be flooded with -+++ memes

Emilio Pisanty

7:15 PM

@AccidentalFourierTransform you play for Achirense?

if so, you have at least one very dedicated fan

AccidentalFourierTransform

??

skullpatrol

@AccidentalFourierTransform did you delete "skullpatrol is fine"?

AccidentalFourierTransform

¿¿

Emilio Pisanty

@Blue I'm pretty sure you haven't

@AccidentalFourierTransform when's the last time you googled yourself?

lılostafa

@EmilioPisanty I will never forget him

AccidentalFourierTransform

7:17 PM

skullpatrol

Best check: try stalking yourself

AccidentalFourierTransform

@lılostafa DELETE THIS

who starred that?

stars are not gonna help, people

please stop

it's not that I really care, but at this point it's making me kinda uncomfortable

Balarka Sen

@lılostafa This is quality humor.

Emilio Pisanty

@Blue (more to the point, if said twitter feed is full of the words boludo, remera, seguinos, hacé, agarrame, then that person isn't from Spain)

Anonymous

@EmilioPisanty Ah, it doesn't seem the person I found on twitter is from Spain

Anonymous

7:21 PM

But the name matches completely

AccidentalFourierTransform

IIRC, I never used my real name on twitter

Emilio Pisanty

@Blue that would be a match to the person who plays for Achirense

@AccidentalFourierTransform there's a person who does, though =P

Anonymous

AFT is fooling us :P

AccidentalFourierTransform

there is a person who does use their real name on twitter?

I bet so :-P

lılostafa

@AccidentalFourierTransform OK, sorry. someone flag that. It's too late for me to delete it myself

Anonymous

7:22 PM

@AccidentalFourierTransform Yes, this Morales guy

Balarka Sen

more importantly there is a person who does use your real name on twitter

Sid

@AccidentalFourierTransform Donald J Trump. :P

Emilio Pisanty

Donald J. Trump

@realDonaldTrump, Washington, DC

45th President of the United States of America🇺🇸

35.7k tweets, 37674k followers, following 45 users

?

AccidentalFourierTransform

ok you got me, I'm Trump

Sid

Ha!

Anonymous

7:23 PM

If Trump knew physics and math......

Balarka Sen

@Accidental Good tweet.

AccidentalFourierTransform

thanks, I made it myself

lılostafa

@BalarkaSen WTH is this real?

Sid

@lılostafa The wonderful power of Photoshop

skullpatrol

@AccidentalFourierTransform did you delete it?

Balarka Sen

7:25 PM

lol no it's a meme by grandayy

AccidentalFourierTransform

@skullpatrol yes, because it got a star

Balarka Sen

you can see his face on the "tweet your reply" section

and the watermark

AccidentalFourierTransform

I didnt want no traces to this conversation

skullpatrol

So?

AccidentalFourierTransform

I expected it to get buried

too late for that anyway

skullpatrol

7:26 PM

ok

np

AccidentalFourierTransform

but you are fine anyway :-P

skullpatrol

:D

Emilio Pisanty

@AccidentalFourierTransform wow, your footballing, argentinian namesake really does play in the middle of nowhere

^ that there is their stadium

AccidentalFourierTransform

no, you got it wrong, I am the football player

:: kicks ball into the thing with the net ::

Emilio Pisanty

well, then, bejeesus, that really is in the middle of nowhere

about the best I can think to say about it is that it is less than four hours' drive away from Buenos Aires

skullpatrol

7:32 PM

Four hours through the jungle?

Emilio Pisanty

@skullpatrol no, four hours through the pampa, just interminable fields with cows in them

boringest drive possible

I once took a bus from Buenos Aires to Mar del Plata and it was brain-crushingly boring

skullpatrol

\o @yuggib

yuggib

@skullpatrol o/

Emilio Pisanty

google.co.uk/maps/@-36.9171266,-57.8789333,3a,60y,351.35h,97.3t/…

then keep on going

yuggib

@0ßelö7 Since $H$ is a closed operator, by spectral theorem $H^{1/2}$ is closed as well, and $D(H)$ is a core of $H^{1/2}$. Therefore you can always find such a sequence by definition of closed operator ($H^{1/2}$ in this case)

Hi, by the way, how are you?

skullpatrol

7:40 PM

@EmilioPisanty nice, you could watch your dog run away for days :P

Emilio Pisanty

@skullpatrol yeah.

Argentina is huge

or as AFT would say, yyyyuuuuuuge =P

Anonymous

Good place to use auto-pilot and go off to sleep :P

Emilio Pisanty

@Blue I wouldn't really class the argentinian pampas as good places to die

CooperCape

8:12 PM

Okay y'all probably will count this as a stupid question (as do I) but I just want a quick check soooo does $\frac{dx}{dt}\frac{dx}{dt} = \frac{d^2x}{dt^2}$

Cause I'm soooo verging on no rn

heather

hello

CooperCape

hi :p

AccidentalFourierTransform

@CooperCape nope

CooperCape

coolio

AccidentalFourierTransform

the first one is the velocity squared

the second one is the acceleration

CooperCape

8:13 PM

It seemed wrong cause $v^2\neq a$

yeah

AccidentalFourierTransform

👍👍

CooperCape

just wolfram alpha said it is but maybe it took the input wrong cause I didn't really check lol

CooperCape

8:36 PM

Guys if I'm evaluating the space-time interval as $$\Delta s=\int_0^{50}\sqrt{\eta_{\mu\nu}\frac{dx^\mu}{d\lambda}\frac{dx^\nu}{d\lambda}}d‌\lambda$$ do I take $c=1$ or $c=299792458ms^{-1}$?

AccidentalFourierTransform

aren't you missing the units on the second one?

CooperCape

yeah apologies

edited :p

AccidentalFourierTransform

ok, so there is no "or" there

the two expressions are equivalent, and true at the same time

CooperCape

Doesn't it drastically change $\Delta s$?

AccidentalFourierTransform

$c=1=299792458\ \mathrm{m\,s^{-1}}$

CooperCape

8:39 PM

Oh right

AccidentalFourierTransform

you cannot change anything by using some units over others

the world is independent of your choice of units

CooperCape

That's kind of it <3

I'ma go with one then

make life easy

AccidentalFourierTransform

ask yourself the following question instead: dies $\Delta s$ depend on whether I use $299792458\ \mathrm{m\,s^{-1}}$ or $c=186282\,\mathrm{ mi\,s^{-1}}$?

of course, it does not

CooperCape

so when c=1 $\Delta s$ will be in units of light-seconds?

AccidentalFourierTransform

¡when $c=1$, $\Delta s$ will be in whatever units $x$ is

which could be literally anything

for example, meters

CooperCape

8:42 PM

okay...

thanks :p

AccidentalFourierTransform

np 👍👍

CooperCape

Slowly tryna get my head around it...

AccidentalFourierTransform

yeah, it takes time :-P

(or space, y'know)

CooperCape

Maaaad bants

CooperCape

9:17 PM

Guys I don't wish to post a looong 'check my work' style question but it's the first one I've done and I kinda made up the parameters so what should I do? Or just ask a teacher to check it over some time later if it's really unacceptable here...

by first one I've done I mean first question of that style

0ßelö7

9:34 PM

@yuggib Ahhhh, because $x\mapsto\sqrt x$ is real (ignoring $x<0$), $H^{1/2}$ is s.a., hence closed?

I'm not sure how to show that $D(H)$ is a core of $H^{1/2}$ though.

@yuggib According to Kato, that means there is a closable operator $A$ on $D(H)$ such that $\bar A=H^{1/2}$.

bolbteppa

Lattices in dimensions 8n?

0ßelö7

@yuggib I have wondered about how $D(f(A))$ is related to $D(A)$ and I never got a straight answer

lılostafa

@HDE226868 Are you sure your astro professor isn't @dmckee himself?

0ßelö7

9:49 PM

@lılostafa different schools

lılostafa

@0ßelö7 Are you sure?

0ßelö7

@yuggib I'm pretty good, how are you? we have two new geometric analysis faculty and are getting a seminar going. I'm going to present some summer research and hopefully some of my work on regularity theory/Sobolev spaces on $\partial$-manifolds

lılostafa

From their profiles we know that HDE226868 is at Swarthmore College, but are sure it's not the same place as Duchy of Grand Fenwick where dmckee is located?

0ßelö7

that place is made up

dmckee is at a different school

trust me

lılostafa

OK then.

yuggib

9:59 PM

@0ßelö7 Yes it is s.a. and hence closed. The relation between $D(f(A))$ and $D(A)$ is also part of spectral theorem, it is probably discussed at length in e.g. Weidmann's book.

@0ßelö7 I am fine, a lot of work lately, but apart from that I can't complain

0ßelö7

@yuggib "Linear Operators in Hilbert Spaces?"

dmckee

10:11 PM

@lılostafa Where's @HDE226868 going? Maybe I'd like to be a prof there.

0ßelö7

@dmckee Swarthmore

I thought you were selling your soul to the GDP :P

dmckee

Perhaps I should talk to them. We haven't had the signing ceremony on the soul deal yet...

But it's so bad I'm planning to apply to Rand.

0ßelö7

@dmckee Ayn?

dmckee

No Rand Corporation. The think tank.

GPhys

When cosmic afterpulsing are dominating your rate T.T

yuggib

10:18 PM

@0ßelö7 yes

0ßelö7

@yuggib I am discovering that there's an $L^2$ spectral theorem that gives a finite measure. I only knew it for sigma-finite. That changes things.

Right, Conway only proves the existence of a sigma-finite space. This seems suspicious.

vzn

so @GPhys you mentioned CERN once, are you doing something there?

0ßelö7

10:39 PM

@yuggib Ok, here's my proof: From Davies Spectral Theory and Diff Ops, we have Thm 4.3.4 which says that $f\in D(H)$ iff $f\in D(H^\lambda)$ and $H^\lambda f\in D(H^{1-\lambda})$ for any $\lambda\in(0,1)$. Note that this implies that $D(H^{1/2}H^{1/2})=D(H)$. Now we apply Thm 5.39 in Weidmann, which says that $D(A^*A)$ is a core for $A$ when $A$ is densely defined and closed. But that's true for $A=H^{1/2}$ and it is s.a. so $(H^{1/2})^*=H^{1/2}$, QED.

@BalarkaSen hola

Balarka Sen

h

Bernardo Meurer

@dmckee Please tell me you're here and know how to use CMake

0ßelö7

11:02 PM

@BernardoMeurer I need a new avatar

Bernardo Meurer

@0ßelö7 I'm trying to compile OpenCV with proprietary malware support right now

It's a mess

0ßelö7

@yuggib Oh, and Kato, p. 275. Kato has everything, damn...

George Smyridis

11:15 PM

Hey guys. I'd like to make a very quick question! Maxwell's Relations in thermodynamics help us calculate how quantities that we cannot directly measure change in respect to a parameter, by measuring how measurable quantities change in respect to another parameter. Now when it come to megnetic phenomena, what are the measurable and what are the immeasurable quantities.

?

heather

@EmilioPisanty congratulations on the new paper!

Bernardo Meurer

11:30 PM

0

Q: Adding Library to CMake on CLI

I'm trying to build OpenCV with CUDA support using Arch Linux's AUR. In their build configuration some options are passed to CMake, I have modified those to add CUDA features. Upon attempting compilation I get the following error: [ 10%] Built target pch_Generate_opencv_reg In file included from...