The h Bar

Alan

3:00 PM

Ah, then it looks like I'll have to wait :(

When're you back next?

John Rennie

Well ask anyway

0celo7

@BalarkaSen My problem in this (and it's my fault for not having read the book yet) is that I'm not sure what the domains of these things are

Like, $\|\omega\|$ is the $C^0(U)$ norm for which $U$?

And that seems like a bad idea: close norms does not mean the things are close

Alan

Ugh, this will take some time. I've been practicing more SHM questions, and there's one on a pulley-spring-block system that I can't solve. Before I bring up that particular question, I wanted to post two others (which I solved in a similar manner), so you could check my reasoning...

So yeah, it'll take time ^ :3

0celo7

$$|\|\omega\|-\|d\alpha\||\le \|\omega-d\alpha\|$$

you really want the RHS to be small

John Rennie

I have about 10 minutes so why not post the first question?

Alan

3:03 PM

Well, I'll post one of the questions I did solve, could you tell me if I went about it correct?

@JohnRennie Okay! :D

Captain Bohemian

@Slereah I recall someone in a facebook group talked about some paper in a website, then another told him everyone can upload papers to that website, meaning papers in that website have no credibility. I couldn't remember the name of that website. Now I think probably that website is just viXra.

Balarka Sen

@0celo7 Ah, yeah, no, this is a fair confusion. $\omega$ is a $k$-form on some neighborhood of $K$ in $V$. Eliash-Misha adopts Gromov's notation "$\mathcal{Op}(K)$ to denote that neighborhood, because they want to leave it winkwinkwink"unspecified"winkwinkwink

John Rennie

@Alan actually let's switch to chat.stackexchange.com/rooms/54160/problem-solving-strategies so we don't interrupt the maths conversation here

Alan

<Nods>

0celo7

@BalarkaSen Why so many winks? Is it not rigorous?

Balarka Sen

3:05 PM

I think they do their best. It's just a notational clusterfuck in that book

Ted asked a symplectic/contact geometer on his trip to GA

and he said it's unreadable, basically

0celo7

@BalarkaSen Ok, I get that the domain of $\omega$ is $\mathcal Op(K)$ (fucking awful typeography)

but wrt. which set is that norm taken?

$K$?

or $h_1(K)$?

Morally one should have $$\|\omega-d\alpha\|_{L^\infty(\tilde K)}<\varepsilon$$

Balarka Sen

Surely the former, because it's a neighborhood of $K$? the norm on Op(K) should be induced from the Riemm. metric on $V$

@0celo7 Well, then what is the $C^0$ business they are blabbering about?

$C^0$ means sup norm, right?

0celo7

@BalarkaSen But the point is that inclusion $V\hookrightarrow M$ just gives the metric $g|_V$ on $V$

pointwise, it's exactly the same thing

Balarka Sen

oh $V$ is our manifold. there is no inclusion

it's a horrendous notation but yeah

0celo7

er

Ok $K\hookrightarrow V$ then

or $\mathcal Op(K)\hookrightarrow V$

Balarka Sen

3:09 PM

okay, yeah, that's how you get the metric

0celo7

When you integrate, yeah, you $\tilde K$ might be very wiggly

But the pointwise norm doesn't care about that

@BalarkaSen certainly

Balarka Sen

and you get changing distance function for the embeddings $h_t : \mathcal{Op}(K) \hookrightarrow V$

0celo7

Yeah. I think you need to write down very carefully what all this means

There seems to be a lot of handwaving in the definitions and statements here

imo

Balarka Sen

i concur

0celo7

0

Q: Doubt in Maxwell's treatise

I am reading Maxwell's treatise Vol 2 page 154 and it seems to me that something is incorrect. Equation (9) is fine. Now let's derive equation 10 from this. A 1954 edition of this treatise (called Dover edition) has $+2C$ inserted but in the forthcoming equations, $+2C$ has been taken awa...

Balarka Sen

3:11 PM

you want to write $\lim_{n \to \infty} \|\omega - d\alpha_n\|_n = 0$ somehow

0celo7

very Indian

Balarka Sen

whatever that means

0celo7

@BalarkaSen right. that subscript $n$ should be $L^\infty(K_n)$, where $K_n$ is "close" to $K$ as $n\to\infty$

something like that

Balarka Sen

Ahh I see ok

That's an enlightening comment

0celo7

cool

@BalarkaSen But that highlights the nature of the issue: there are two changing things, the domain and the $\alpha_n$. So I wouldn't expect an integral to necessarily make sense as $n\to\infty$.

Balarka Sen

3:16 PM

Yup

That makes much more sense; thanks a bunch. I'll ponder on it more

0celo7

np

@BalarkaSen so should I not read the book?

Balarka Sen

there's no better book :p

0celo7

I bought it cuz it was cheap and I need to learn the h principle

Balarka Sen

so yeah you should if you want to

unless you want to read Gromov lol

0celo7

I actually need to read Gromov but my advisor said it's legendarily hard

Balarka Sen

3:18 PM

What from him?

0celo7

the h principle book

Balarka Sen

ah ah ok

0celo7

The singularity analysis is important for scalar curvature geometry

Balarka Sen

I think his approach is different there

he does convex integration theory

0celo7

I dunno

but as of Dec 2017, the only proof of the spacetime positive mass theorem that I know of uses the h principle

(among other things)

Balarka Sen

3:21 PM

I am averaging my response between "that's pretty cool" and "well that's fucked then"

Captain Bohemian

is spacetime positive mass theorem just gravitational positive energy theorem?

0celo7

@CaptainBohemian yes

@BalarkaSen Oh it's definitely fucked

the consensus is that the guy who wrote the proof is insane (and not in a Gromov way)

Captain Bohemian

then my master advisor's paper provided a proof for it.

use spinor

0celo7

Your advisor was Witten/Lee/Parker/Bartnik/Taubes?

Captain Bohemian

Witten's postitive energy proof

0celo7

3:24 PM

Of course I know that proof, but if you don't see the issue with it then this isn't a worthwhile conversation.

Captain Bohemian

no, but my advisor published the paper independently from Witten

0celo7

Is your advisor one of the people above?

Captain Bohemian

no

0celo7

Who is he?

Balarka Sen

probably worthwhile to link the paper then

Captain Bohemian

3:25 PM

but my advisor's proof is just Witten's

Nester

0celo7

The spin condition is bad

I like Witten's proof though, because it gives a formula for the mass which is useful

Captain Bohemian

I actually worked with my advisor to investigate that formulation for angular momentum

but didn't succeed in getting one

then he suggested me investigate another spinor formulation

Curio

3:46 PM

Has Pd 18 electrons of valence?

John Rennie

4:02 PM

@Curio have you ever seen a compound $Pt X_{18}$ ?

where $X$ represents some other atom

Sid

@Curio Nope. I think there was Octet(?) rule that says that max valence electrons in an atom could only be 8.

John Rennie

4:21 PM

Look on my works, ye Mighty, and despair (of my cooking skills):

That is a giant chilliburger pizza!

0celo7

...

Anonymous

@Curio Valence electrons are not very well defined for transition metals. It's an outdated concept. You could have a look at this anyway: dl.clackamas.edu/ch104-06/valence_electrons.htm

Anonymous

@JohnRennie Lol...that's some cool stuff :D

Anonymous

What's on the top?

Anonymous

And what's inside?

Sid

4:23 PM

Is that a burger or a pizza?

Anonymous

@Sid A burger pizza

Anonymous

It looks a bit flattened :P

John Rennie

@Sid It is a giant chilliburger flattened onto a pizza and the two cooked together so the juice from the burger soaks into the pizza.

If food were pornography that would get me arrested for gross indecency :-)

Sir Cumference

@JohnRennie I dunno what I walked into

John Rennie

Pizza burger KA BAAB!!!

Sir Cumference

4:27 PM

I see

Anonymous

So is that chicken inside?

John Rennie

@Blue Beef and chilli

0celo7

@BalarkaSen Big Sean watches Rick and Morty (do you know who that is?)

Anonymous

@SirCumference JR having a dirty mind is not something new...:p

Anonymous

@JohnRennie Nice...I don't remember having a beef pizza or burger

Sir Cumference

4:29 PM

God it's like negative 1 million degrees here...

Have you guys had snow yet? (assuming you get snow)

yes

yes

of course

ok...

Anonymous

no ;_;

Anonymous

4:30 PM

(Well, it never snows here)

Anonymous

So that doesn't count

0celo7

how sad for you

Sir Cumference

So you've never seen snow?

0celo7

that might explain things

Anonymous

@SirCumference Maybe....but I was too young then...to remember. In some Indian cities it does snow, but those are exceptions. Where I live currently it doesn't snow

0celo7

4:33 PM

I think that snow and JEE is inversely related.

John Rennie

@Blue The northern tip of India gets into the Himalayas doesn't it?

Sir Cumference

@Blue Come to the US/K

0celo7

Less snow --> more JEE

Anonymous

@JohnRennie Right...near the Himachal area...we used to live there for a short while

Anonymous

But I don't remember any of it

Anonymous

4:34 PM

Probably I was like 1-2 years old

John Rennie

That's got to be some amazing scenery ...

Anonymous

0celo7

that looks like snow

Anonymous

Guess so...this is Shimla ^

0celo7

I think he was talking about the mountains

Sir Cumference

4:36 PM

Snow's only good when it's falling. If it gets warmer the next day, it turns to disgusting sleet. If it gets colder the next day, it turns to lame ice.

0celo7

ice is cool

great source of slippage

Balarka Sen

@0celo7 i guess the mainstream rap culture is getting WOKE

Loong

Not much snow here right now

Sir Cumference

@0celo7 was that a pun

0celo7

no

I never think about puns

they are the lowest form of wit

Sir Cumference

4:39 PM

@0celo7 well yeah but they're fun to make

0celo7

no

Sir Cumference

ya gotta enjoy the simple things

John Rennie

My house this morning...

0celo7

@SirCumference no

European cars look so strange

John Rennie

Do they? I thought Ford Focuses (Foci) were the same all over the world?

0celo7

4:42 PM

...I don't see a focus in that pictre

John Rennie

My car is a Ford Focus

0celo7

the hatchback model

John Rennie

Yes

Most small cars are hatchbacks in the UK

0celo7

@JohnRennie which is strange

John Rennie

I've never really thought about it. Hatchbacks are very practical - it's easy to get stuff in and out of the back.

0celo7

4:52 PM

@JohnRennie Meh.

Sometimes one must sacrifice practicality for style.

John Rennie

@0celo7 I've owned my fair share of fast sports cars, but they've generally been fastbacks.

Sir Cumference

@Blue So, how cold is it where you are?

0celo7

@JohnRennie so you've gotten boring in your old age?

Anonymous

@SirCumference 22 C at the moment

John Rennie

@0celo7 It's true

Anonymous

5:04 PM

@0celo7 That's quite logical.

Anonymous

@SirCumference Yeah, I'm trying to flee from this place asap

Sir Cumference

@Blue You mean for break or transfer?

Anonymous

@SirCumference Higher studies after my undergrad is over. I don't know if transfer is feasible...like getting funding is pretty damn hard (for undergrad transfer)

Anonymous

I might just take the TOEFL next year...

Anonymous

(The main reason is that the education system here is quite suffocating, and very few people care about things other than getting a job after graduating. Also funding for research is quite low.)

Sir Cumference

5:12 PM

@Blue Preaching to the choir

Anonymous

hmm

0celo7

@Blue you know, people always say that to me

I think I'm at the pinnacle of modern logic tbh

@BalarkaSen Hmm. I emailed my fluid mechanics prof about the final and he said I already have an A in the class with what I sent him.

To continue or not to continue?

@JohnRennie ugh how do you remember the copy syntax

I can never remember which way it goes

it's source, then destination, right?

John Rennie

You mean the Windows command prompt copy command? If so yes it's copy source destination

0celo7

well, linux

John Rennie

The cp command?

0celo7

5:19 PM

what the heck is fort.1

what is a .1 extension??

John Rennie

Can't remember, use cp -? to get the syntax.

@0celo7 temporary files usually

0celo7

aha

it happened during debugging

I accessed a file that I had closed

it was file unit = 1

ooolb

@JohnRennie aaaaaaaa

why don't we have snow here yet

jelly

Anonymous

@0celo7 And yet you choose to do mathematics. ;)

Anonymous

Go and increase GDP

ooolb

5:29 PM

sure modern logicians in the philosophy department are single handedly sky rocketing the GDP

Anonymous

@ooolb Those are fake logicians

Anonymous

@0celo7 is the real deal

John Rennie

@0celo7: should I buy this?

ebay.co.uk/itm/322920185484

Anonymous

@JohnRennie That sounds like a rhetorical question ;)

John Rennie

@Blue Ryan was nagging me about getting a proper mechanical keyboard.

ooolb

5:35 PM

@JohnRennie do you use your number pad?

John Rennie

Yes

ooolb

do you now what kind of keys you want?

0celo7

@JohnRennie I don't think Logitech mechanical keyboards are the best

ooolb

that one's brown

0celo7

Although the switches are what matters

You need to get a sampler so you can see which you like best

Balarka Sen

5:37 PM

@0celo7 sounds like that depends on what you want to do

0celo7

I have CMX Reds, my dad has Blue

Anonymous

The main problem with those keyboards is that they get very dirty after sometime. Dirt particles accumulate under the keys.

John Rennie

@0celo7 I want the brown switches because I like a positive feel when I type.

0celo7

@Blue You take off the keys and attack it with canned air.

John Rennie

I won't be using it for gaming so I don't need the red switches.

ooolb

5:37 PM

I use blues

dunno if that's biased

but i like them

Sid

@JohnRennie Are you even involved in gaming?

John Rennie

@Sid No

Anonymous

@0celo7 All keyboards don't have removable keys I think...

Sid

@JohnRennie You should.

0celo7

@Blue All mechanical keyboards do.

ooolb

5:38 PM

@JohnRennie I could imagine you as a pro minesweeper player.

Sid

(Gah. I just watched the World Chess Champion blunder something I wouldn't ever do.)

Anonymous

@0celo7 Not sure...I had one of those and had tried to take out a key. It broke

Anonymous

Better check before buying

0celo7

with Cherry switches?

John Rennie

I used to play Doom and Quake fanatically, but at some point in the last five decades I appear to have grown out of gaming. Oh well :-)

ooolb

5:39 PM

does anyone remember MAFIA?

Sid

Makes me feel so much better about myself as a chess player

ooolb

did he come back ever

0celo7

he didn't

he also never responded to my email

ooolb

hmmm

Balarka Sen

It's been a long time since I played chess

0celo7

5:40 PM

@Blue you probably rammed around and weren't careful

John Rennie

Anyhow, awaiting my attention I have:
1) an armchair
2) a glass of beer
3) this week's New Scientist

ooolb

i don't really like chess because my skills lie in making fast and mostly strategic decisions instead of slow and fully strategic

John Rennie

And I might even watch Arrival after I've finished New Scientist

ooolb

and who has the patience to wait like 30 seconds every turn that's lameeeee

Sid

@ooolb Play rapid matches

ooolb

5:41 PM

maybe

i haven't played it since chess club in grade 5

Balarka Sen

@JohnRennie I recommend "Primer"

Absolutely amazing movie

Sid

@BalarkaSen Primer is mindfuck.

Balarka Sen

I love it

ooolb

@BalarkaSen should i watch it right now?

Balarka Sen

Do it

ooolb

5:42 PM

i need to wait for my laundry to finish before i go to the library

i have time

Balarka Sen

It will mess your brain up

it's an hour long

ooolb

it can't get any more messed up

ya laundry+dry takes an hour

Slereah

Primer is boooring

Balarka Sen

ur boring

Slereah

It's not even a particularly realistic movie

There are no hard sci fi movies, really

ooolb

5:44 PM

did you watch rick and morty?

Slereah

Yes I am aware of the memes

no need to go through them

ooolb

that was a meme

were you aware of that too?

Slereah

Yes

I am aware of all things

ooolb

impressive

Slereah

^me

ooolb

5:45 PM

that's like the 3rd row in the expanding brain meme

Balarka Sen

Marx debunked Rick and Morty yeaaaars ago

Anonymous

Looks like an ordinary brain with a light bulb.

0celo7

hmm

should I play Metal Gear, write more of my thesis, or work on Dirichlet heat kernels?

or watch the Sopranos

Slereah

Which Metal Gear

Trick question

0celo7

5

Slereah

5:46 PM

Don't play Metal Gear

It's a dumb series

Balarka Sen

every night

i can feel my legs

0celo7

@Slereah what is wrong with you

Slereah

I only like good video games

Balarka Sen

my comrades

Slereah

it is my curse

ooolb

5:47 PM

owh

Anonymous

Why is ACM's message pinned? Are too many people planning to kill each other?

Balarka Sen

if you are into action and mindfuck both

you could watch

Snowpiercer

a 8.9/10 movie

0celo7

@Blue I agree. It's ridiculous.

ooolb

@BalarkaSen I watched that

I didn't really get the end

0celo7

hail hydra

Balarka Sen

5:49 PM

they blasted the train

boom

ooolb

what was the point of all of it

it didn't make sense

Balarka Sen

of what

ooolb

idek this was a long time ago

Slereah

Really I find it odd that Hydra got so powerful

ooolb

but i remember not being satisfied

Slereah

5:50 PM

You'd think a nazi skeleton wouldn't have that much charisma

0celo7

@BalarkaSen I'm leaving do Carmo to you in my will

Balarka Sen

is Captain America still a member of Hydra

Slereah

Who knows

comic books are for children

0celo7

he was a member of hydra?

Balarka Sen

a storyline revealed him to be as such

ooolb

5:51 PM

@Blue idk man

Balarka Sen

and the whole world went crazy

ooolb

@Blue nobody threatened to hunt down anybody

Sid

@BalarkaSen wait, what?

Balarka Sen

yeah it was dumb

ooolb

i feel that message is wholly useless

Balarka Sen

5:52 PM

it's like fucking batman finding out that he killed his own parents

ooolb

why it's pinned is beyond me but i don't care

Anonymous

@ooolb Hmm, anyway you shouldn't piss off ACM ;p

Balarka Sen

the whole story becomes ridiculi

ooolb

@Blue ACM is different now

Slereah

@ooolb Software update?

Anonymous

5:54 PM

@ooolb Maybe his recent upgrade has some bugs...who knows

Slereah

JINX

Balarka Sen

GEEK TV - What's in the bag?

►

0celo7

@ACuriousMind I summon thee. (QM)

ooolb

rye likes drama

0celo7

What?

Slereah

5:57 PM

What QM do you wonder about

Sid

@BalarkaSen Imagine this story line. Batman finds a time machine, goes back in time to save his parents and then somehow manages to kill his parents but the younger Batman doesn't realize that. And the world comes a full circle

Slereah

This probably already happened

Sid

(He gets time machine from Doraemon. Lol)

Balarka Sen

@Sid "Congratulations! Your Sid has evolved into a Zack Snyder!"

Slereah

Do u mean hack snyder

Balarka Sen

6:03 PM

That's a further stage of evolution for this Pokemon

ooolb

@0celo7 grisaia no kajitsu

i randomly remembered that but i think it's exactly what you're looking for

Anonymous

@Sid Pretty sure there are some unofficial comics with that story-line

Anonymous

Fan-made mostly

ooolb

6:15 PM

@BalarkaSen idk if you've ever listened to wave but it's a new genre that's like the merger of a bunch of different genres (trap, bass, techno, dub, etc) and I think you'll like it. also it's really active right now. @0celo7 if you like trap you'll probably like wave because it's most similar to trap.

here's a random one from one of the popular wave channels.

DEITY - AN ELUSIVE MEMORY

►

Curio

6:49 PM

Why doesn't palladium have 18 electrons of valence despite it has 18 electrons in the last level(4 in this case)?

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