The h Bar

0celouvskyopoulo7

14:24

@SpiralRain Spiral RAIIIIIN

Some stay dry and others stay the same

yuggib

@Slereah No we don't, at least in the relevant dimension 3+1

0celouvskyopoulo7

lol

I meant feel the pain

That's what I get for talking and typing at the same time

@Slereah So these page numbers are different than what's reported in the paper I'm reading

Who knows wtf is going on

Slereah

I'm guessing that before computers, page numbers were hard to guess in your manuscript

you might miss a few

yuggib

Also, it is not clear whether triviality is a specific feature of the regularization process chosen (lattice approximation and high-energy cut off), or an intrinsic property of the theory

Slereah

quite unfortunate

Do we know if it is in 1+1D at least

yuggib

14:31

@Slereah at least it is not clear to me

It is not trivial in 1+1

it is not trivial in 2+1

Slereah

I mean whether or not it depends on the regularization

yuggib

it is trivial in $n+1$, $n\geq 4$

Slereah

Why is $4$ always the shittiest dimension

It's always the dimension in between

Secret

exotic sphere in dim 4 = unknown, exotic R^4, etc.

John Rennie

@Kaumudi.H you around?

0celouvskyopoulo7

14:33

@Slereah well, they're off by 800 pages

and the number of pages is different

wonder if it has what I need

yuggib

@Slereah Well, in $1+1$ we have a renormalized dynamics. Whether it is the only possible dynamics up to unitary equivalence that satisfies all the axioms etc. for a scalar field I am not sure it is proved

but maybe it is

Slereah

Why can't we live in 5 dimensions

Or 1 dimension

Secret

> Because 3 is special

0celouvskyopoulo7

that font is pretty fire though

yuggib

the paper is pretty thin as well

it is possible to read the other side through a scan/photo

Slereah

14:36

@0celouvskyopoulo7 Is that the fancy way to write Klein Gordon

0celouvskyopoulo7

I have no idea what Yvonne is trying to do there

I haven't read the paper yet

it's also in French, so it will take a while

yuggib

@Slereah should there not be a metric also on the second term?

apart from that, it seems the KG Hamiltonian

0celouvskyopoulo7

also that typo lol

$d\mu(g))$

how did no one catch that

yuggib

typos are a bitch

you'll never catch them all

no matter if you're a referee or the author

I have never made a paper without typos

Slereah

plus you don't want to redo a paper for a typo in the olden days

Sha Vuklia

14:39

Slereah

Don't wanna retype the whole page

Sha Vuklia

Just out of curiosity; why are we considering a line charge? Would something go wrong if we considered a point charge that travels down the wire?

0celouvskyopoulo7

Is a vector bundle in French just a "fibre"

Bernardo Meurer

I'm back

yuggib

@0celouvskyopoulo7 without accent is a fiber

fibré is a bundle

0celouvskyopoulo7

14:40

what's the difference

@Slereah hahahahahhaah

they reference another paper in the same journal I don't have

It should be criminal to not put journals online

yuggib

one is the whole bundle, the other just one fiber of the bundle

0celouvskyopoulo7

@yuggib I know the mathematical difference

what does that little accent do

yuggib

change the word?

0celouvskyopoulo7

ffs

never mind

yuggib

in french, fibre and fibré are two different words

John Doe

14:41

Does anyone know how a direction eigenket is defined?

0celouvskyopoulo7

is the french abbreviation for constant "cte"?

@yuggib They look the same to me, modulo that accent. How does the accent affect the pronunciation?

yuggib

@0celouvskyopoulo7 it does

in a relevant way

0celouvskyopoulo7

it does what?

I asked How

yuggib

change the pronunciation

0celouvskyopoulo7

Clearly it does something

Oh come on

yuggib

14:43

how am I supposed to tell using english words

and I don't know the phonetic alphabet

Sha Vuklia

(oh I get it. the entire thing is the line charge. I thought the thing depicted was the wire)

yuggib

apparently, this is fibre's pronounciation:
/fibʁ/

This is fibré:
\fi.bʁe\

0celouvskyopoulo7

ah, ok

ACuriousMind

@0celouvskyopoulo7 I thought you couldn't read IPA?

John Doe

@ACuriousMind Can you maybe see why the direction eigenket $| \hat{z} \rangle$ (which I assume is defined as $|\theta = 0, \phi \rangle$) is an eigenket of $\hat{x}\hat{p_y} - \hat{y} \hat{p_{x}}$ with eigenvalue $0$?

0celouvskyopoulo7

14:50

@ACuriousMind why would you think that?

John Rennie

@ShaVuklia presumably $\lambda$ is the charge per unit length?

Sha Vuklia

@John yea I understand the idea now

and that is true indeed

I thought the wire they depicted was the wire they were talking about

ACuriousMind

Sep 4 '16 at 20:42, by 0celo7

@ACuriousMind how do you learn to read that

0celouvskyopoulo7

@ACuriousMind I figured it out?

Why do you find that hard to believe?

ACuriousMind

I don't find that hard to believe

It's just new information

Emilio Pisanty

14:53

@ACuriousMind I find that hard to believe

ACuriousMind

@JohnDoe ...Because that operator there is $L_z$?

Emilio Pisanty

@JohnDoe what do you mean by that, and what do you want to use it for?

0celouvskyopoulo7

@EmilioPisanty Why do people like trolling me :/

yuggib

@0celouvskyopoulo7 You can clear all skepticism by recording your own pronunciation of the two words following the IPA guidelines ;-)

Emilio Pisanty

@0celouvskyopoulo7 because you feel trolled even when other people troll yet other people

ACuriousMind

14:55

Troll the room and the room trolls back.

0celouvskyopoulo7

@ACuriousMind Are you suggesting I troll?

Emilio Pisanty

also, that

0celouvskyopoulo7

What evidence do you have

Also that's Not Nice

Emilio Pisanty

To be fair, he could be suggesting that just to troll you

... as part of the room-trolls-back campaing, of course

John Doe

@ACuriousMind Okay but why does $L_{z}|\hat{z} \rangle = 0 | \hat{z} \rangle$?

ACuriousMind

14:56

@0celouvskyopoulo7 Maybe I'm suggesting EP is trolling.

@JohnDoe Well, what's your definition of $\lvert \hat{z}\rangle$?

Emilio Pisanty

@JohnDoe is $|\hat z\rangle$ symmetric under rotations about the $z$ axis?

ACuriousMind

(I don't know what the angles you wrote there mean)

John Doe

@EmilioPisanty It is something stated in a section on Spherical Harmonics and Roat

Emilio Pisanty

@JohnDoe yeah, well, if you don't say which book, saying which section won't help much

yuggib

Can I suggest to stop using the word trolling? I am thoroughly annoyed by neologisms, especially the ones that do not come from appropriately chose latin words

Emilio Pisanty

14:58

but it's a general principle

Slereah

Cte is constant yes

ACuriousMind

@yuggib Would you prefer we call it troglodyting?

John Doe

@EmilioPisanty Sakurai's "Modern Quantum Mechanics"

Emilio Pisanty

if $|\psi\rangle$ is symmetric under a continuous symmetry $S(s)$, where $s\in\mathbb R$ is a continuous parameter, then it is a zero-eigenvalue eigenstate of the generator of said continuous symmetry

which is usually of the form $i\frac{dS}{ds}$ or similar

yuggib

@ACuriousMind It's still not from latin, but yes, that's better ;-P

Emilio Pisanty

14:59

in this case, $L_z$ generates rotations about the $z$ axis

ACuriousMind

@yuggib Well, it's Greek, so even more ancient! :P

Emilio Pisanty

if $|\hat z\rangle$ is symmetric under rotations about the $z$ axis, then it immediately follows that $L_z|\hat z\rangle = 0|\hat z\rangle$.

John Doe

@ACuriousMind He doesn't really give a definition of the direction eigenkets, but he calls them direction eigenkets and usues it as if it is $| \hat{n} \rangle = | \theta, \phi \rangle$, hence I assumed $|\hat{z} \rangle = | \theta = 0, \phi \rangle$.

Emilio Pisanty

so all you have to examine is that symmetry proposition

@yuggib what's wrong with Norse etymologies?

are you biased against scandinavians for some reason?

ACuriousMind

@JohnDoe What sort of state is $\lvert \theta,\phi\rangle$?

John Doe

15:03

@EmilioPisanty What's your reasoning for why it immediately follows if $| \hat{z} \rangle$ is invariant under rotation?

@ACuriousMind Position eigenstate I guess

Emilio Pisanty

@JohnDoe The rotation operator is $e^{i\theta L_z}$

modulo a minus sign in the exponent which I can never recall

saying the state is symmetric under rotations codes into $e^{i\theta L_z}|\psi\rangle = |\psi\rangle$

just differentiate w.r.t. $\theta$.

Jaime Gallego

Howdy y'all

Emilio Pisanty

@JaimeGallego that Hitler topology vid is fantastic

John Doe

@EmilioPisanty Yes that does make sense.

@EmilioPisanty Have you worked through Sakurai?

0celouvskyopoulo7

I should rewatch that video now that I am a topologer

yuggib

15:09

@EmilioPisanty maybe...I am surely biased pro-latins

@0celouvskyopoulo7 you're a what?

Jaime Gallego

@0celouvskyopoulo7 How often do you hear the "ah, you're a surveyor!"

user228700

@JohnRennie Hi :-) I'd gone out (hair+library), sorry.

John Rennie

@Kaumudi.H Oh yes, you've had your hair cut. Did you lose all your strength?

0celouvskyopoulo7

@yuggib A topologer

I use topology a lot, but I'm not a topologist

user228700

Haha, very funny :-) I had it cut just now. It looks very nice! Also went to the library and got three books.

0celouvskyopoulo7

15:12

@JaimeGallego Yes, people do often confuse topology and topography

Emilio Pisanty

@JohnDoe no

0celouvskyopoulo7

But I don't tell people I am a topologist

I say I am a geometer, and they think I mean I study triangles.

yuggib

@0celouvskyopoulo7 I see, so it is like the advanced topology amateur :-D

John Doe

@EmilioPisanty No prob.

yuggib

then I am a topologer as well

ACuriousMind

15:13

@0celouvskyopoulo7 The proper answer to that is "no, I have progressed to rectangles".

0celouvskyopoulo7

@ACuriousMind hahah

user228700

@JohnR: 29 minutes left. I'll tell you how it goes...

user228700

Did u buy the maggi?

0celouvskyopoulo7

@ACuriousMind Is an algebrer

He is not an algebraist, but uses it a lot

John Rennie

@Kaumudi.H Ah, OK, you must have a pretty good Internet connection. If it works let me know and I'll sort the other two files.

@Kaumudi.H I didn't in the end. I felt like something sweet rather than savoury so I bought some fruit, which I thoroughly enjoyed :-)

yuggib

15:14

@0celouvskyopoulo7 how do you qualify to be an "-ist"?

user228700

I do, I do. In fact, I'm going to put away my laptop in just a bit and place it next to the router; I'm in a whole other room and being here is not helping the download.

user228700

@JohnRennie Ah, OK :-)

0celouvskyopoulo7

@yuggib Your main object of study has to be in that field

Jaime Gallego

@0celouvskyopoulo7 He fixes people's bones, I see

ACuriousMind

@0celouvskyopoulo7 I'm currently trying to translate an algebraic cohomology argument to deRham cohomology to see what explicitly happens to the forms, actually

0celouvskyopoulo7

15:15

For example we use topology a lot (in functional analysis), so we are topologers

But our goal is not to study topology

John Rennie

@Kaumudi.H I felt like something sweet - which is strange because I don't look like something sweet :-)

0celouvskyopoulo7

@ACuriousMind uses god awful algebra to do whatever, but his goal is not algebraic

user228700

Back with the dad jokes, I see! :-)

yuggib

@0celouvskyopoulo7 I think that the goal of nobody is studying topology since 60 years ago

John Rennie

@Kaumudi.H I fired up my new massive laptop to do the video processing and oh my goodness it's fast!

0celouvskyopoulo7

15:17

@yuggib My school has a large group of pure topologists

shape theory

things like that

user228700

@JohnRennie Ah, that's great! It was a great deal, then!

0celouvskyopoulo7

And there's plenty of people studying algebraic/differential topology, so I don't know what you're talking about.

yuggib

I am not sure that there is much that has not been already said in general (pure) topology

John Rennie

@Kaumudi.H Definitely! See, I don't just buy these laptops for fun - I do have good reasons :-)

yuggib

algebraic/differential topology sound more like applications of topology to me

user228700

15:19

@JohnRennie :-P Sure, sure.

ACuriousMind

@JohnRennie What sort of video are you processing? Do I want to know?

John Doe

@EmilioPisanty Is it correct to write the working as $\frac{d}{d \theta}[e^{i \theta L_z}| \psi \rangle] = 0 \implies i L_z e^{i \theta L_z}| \psi \rangle = 0 \implies L_z| \psi \rangle = 0$

John Rennie

@Kaumudi.H Honestly :-)

user228700

:-)

0celouvskyopoulo7

@yuggib They are still topology...

Jaime Gallego

15:21

@JohnRennie I think your surname would be great as the name of an unit

Specifically, laptop sales.

user228700

OK, I'm going to put away the laptop now. I'll ping you when I find out if it came out OK @JohnR. Thank you! :-)

Jaime Gallego

the demand for Surface Pro increases 2.71 rennies this week...

3

John Rennie

@ACuriousMind Lord of the Rings films. I'd forgotten how long they are. Resampling a 3 hour film really tests a laptop - if the cooling fans were running any faster it would take off!

@JaimeGallego it's a unit of indigestion! :-)

@JaimeGallego that would be 2.71 picorennies. The Rennie unit for laptops is far too large for most purposes :-)

user228700

(@JohnR: book I'm starting now)

John Rennie

exhilarating and heart-wrenching love story - urp, I feel nauseous!

user228700

15:23

@JohnRennie x'D I wasn't able to find any book from my list at the library.

John Doe

@ACuriousMind Does my above working look correct?

0celouvskyopoulo7

@JohnRennie How many laptops do you have?

Jaime Gallego

MIT undergrads had a game where they named units after each other and defined what magnitudes they measured

0celouvskyopoulo7

@JaimeGallego that seems like a stupid game...

ACuriousMind

@JohnRennie Oh, so many inappropriate jokes in "the microrennie unit"...

user228700

15:24

Well, except one (The Giver #1) and I didn't want to start with that; thought I'd start with something stupid easy to read so that I could get back into the flow.

John Rennie

@0celouvskyopoulo7 Nine I think. I'd have to go count them to be sure, but that's about right.

Jaime Gallego

mitadmissions.org/blogs/entry/units-of-measure

user228700

Wokay toodles till whenever this file finishes downloading!

John Rennie

@ACuriousMind :-)

yuggib

@0celouvskyopoulo7 then also a big part of topology applied to functional analysis is still topology

My opinion is that the boundaries between various subjects are often not so clear

0celouvskyopoulo7

15:27

@yuggib I don't disagre

But neither of us are topologists, but use some kind of topology daily

That's fair

yuggib

probably so

0celouvskyopoulo7

@ACuriousMind $A-B$ or $A\setminus B$

The latter is growing on me

yuggib

for what?

ACuriousMind

I prefer $A-B$

@0celouvskyopoulo7 Then you should consult a doctor, that doesn't sound like a healthy growth

0celouvskyopoulo7

@yuggib sets

yuggib

15:30

set difference? I agree that the latter is not good looking, but if your sets have also some other structure, the first notation could be misleading

for example, if the objects in the sets have a linear structure, I would interpret $A-B$ as the set $\{a-b, a\in A \land b\in B\}$

for function spaces, the notation is quite common: $L^p+L^q$ is often used for the set of functions consisting of the sum of a part in $L^p$ and the other in $L^q$

0celouvskyopoulo7

Yes, I have seen $+$ for vector spaces.

yuggib

If you deal e.g. with cones, you can also see the $-$

John Rennie

@Kaumudi.H the download just finished - did it work?

user228700

@JohnRennie 27 seconds left...

Slereah

finally home

John Rennie

15:42

@Kaumudi.H Ah that's odd. I've been watching the network traffic on my server and it has just gone to zero.

user228700

Yaay, it works! :-D

John Rennie

Maybe there's some data being buffered somewhere.

@Kaumudi.H OK, I'll sort the other two files, but they will take a while to process even on my super-duper new laptop (have I mentioned my new laptop recently? :-) I'll ping you when they're done.

Slereah

I should read up some AQFT on Schwarzchild

I need a good example of a construction that isn't Minkowski space

user228700

@JohnRennie :-) Take ur time, please!

John Rennie

Well it isn't taking any of my time since I just queue up the files to be processed, press the Go, go, go! button and go back to trying to explain Noether's theorem to PhyEnthisiast.

user228700

15:47

:-P Right, OK...

Jaime Gallego

@Bernardo It was dhcpcd all along, disabling the service works wonders. Spooky.

ACuriousMind

@JohnRennie Is the button labeled actually "Go, go, go!"?

Slereah

The pile gets soaked with data and starts to get mushy over time, so it's technically recurrent.

Bernardo Meurer

@JaimeGallego dhcpcd was messing with your graphics?!

John Rennie

@ACuriousMind Only in my mind :-) I use software called Handbrake and the button actually says something really boring like Start Encoding.

ACuriousMind

15:49

:(

Jaime Gallego

@BernardoMeurer Weirder than your MIPS eh?

Bernardo Meurer

@JaimeGallego Nothing is weirder than my MIPS bullshit :P

It only gets weird when you have sneaky interrupts coming from nowhere

user228700

I'll get back to my book, then...

John Rennie

@Kaumudi.H you know you can connect your laptop to the TV so it displays on the TV screen? That's really good for films.

0celouvskyopoulo7

Damn.

user228700

15:52

Don't you need to have a specific type of T.V for that sort of thing?

John Rennie

Any TV with an HDMI connector.

Jaime Gallego

Maybe it's because both graphics and dhcpcd start on boot and they interact with each other.

Black magic

ACuriousMind

@0celouvskyopoulo7 You forgot spaces again

John Rennie

@Kaumudi.H That's pretty much any flat screen TV, though not the older style TVs with a cathode ray tube.

user228700

Ah, OK, I'll check it out then. Timely advice too, since, as you remember, my headphone jack is bust.

John Rennie

15:54

You need a micro-HDMI to HDMI cable.

user228700

Hmm, I might just have one of those lying around...

user228700

If not, the nearest one is available 10 minutes away so :-)

John Rennie

Let me just check it is micro-HDMI ...

0celouvskyopoulo7

@ACuriousMind I don't know what that means

ACuriousMind

May 4 at 19:06, by ACuriousMind

Chat inserts invisible "break" characters after 50 oder so consecutive characters without a space

Transcript for