The h Bar

12:07 AM

@heather Whenever you're here. . .

I just wanted to apologize for the abuse you suffered from that user on HSM. His/her actions were uncalled for and extremely offensive.

I do hope you'll keep coming back to HSM in the future.

I know that there are folks who will attack you because of your age. I've been through that, too (to a lesser degree).

But I hope you'll ignore them. You're a smart person.

0celo7

@HDE226868 what happened?

HDE 226868

@0celo7 There was an incident on HSM with an abusive user.

0celo7

@ACuriousMind hsm.stackexchange.com/questions/5828/…

;)

ACuriousMind

12:11 AM

@HDE226868 Any reason hsm's chat room has no owners? (Aside from it being completely dead, that is :P)

0celo7

-2

Q: I have a question about e=mc squared

I was wondering if anybody knew exactly what E=mc squared meant. I already looked online, but I got many different answers. Someone please help me if you can. Thanks! I am also not totally sure if this a correct tag for this topic so let me know if otherwise.

scientific-method

???

why isn't this closed

ACuriousMind

@0celo7 Hm?

0celo7

@ACuriousMind Weinberg's crazy notation

Bernardo Meurer

What happened on HSM?

ACuriousMind

@0celo7 It doesn't have half a dozen indices trailing off it, it's not that bad :P

HDE 226868

12:12 AM

@ACuriousMind It's deader than John Cleese's parrot. That's it. :P

Bernardo Meurer

Did they free themselves of proprietary malware?

HDE 226868

@BernardoMeurer I'm not going into details.

ACuriousMind

@HDE226868 I doubt a chat room can pine for the fjords, though ;)

0celo7

1

Q: How is "soul" meant to be understood in the context of the "Soul Theorem"

My mathematics are still quite rudimentary, but am I correct in assuming this is a reference to the "finite" state of closed manifolds as opposed to a potential, "infinite" state of the non-compacted case?

terminology riemannian-geometry

HDE 226868

@ACuriousMind That's why it's deader.

Bernardo Meurer

12:13 AM

@HDE226868 I'd fight you, but you're not worth it

0celo7

@HDE226868 some of these questions are very bizzare

HDE 226868

@BernardoMeurer Meh. You'd probably win.

Bernardo Meurer

No, no, not physically

0celo7

Someone asking about a very complex theorem in geometric analysis, which is not really an advertised theorem, then saying "my mathematics are rudimentary"

like what?

Bernardo Meurer

I mean just throw shit at your OS choices and get banned after calling you something ACM doesn't like

that's my kind of fighting

HDE 226868

12:14 AM

@BernardoMeurer How's Ubuntu?

0celo7

haha

Bernardo Meurer

I hate Ubuntu

0celo7

Ubuntu

hahaha

Bernardo Meurer

Canonical is has that bullshit amazon thing

ACuriousMind

@0celo7 I'll bet they just were searching for "soul mathematics" or something similar and stumbled across that :P

Bernardo Meurer

12:14 AM

Unity is garbage

Mir is a wasted effort

HDE 226868

@BernardoMeurer What OS do you use?

Bernardo Meurer

apt is a shitty package manager

@HDE226868 On this machine Arch Linux, on my server I run FreeBSD

HDE 226868

@BernardoMeurer Huh, interesting.

0celo7

@ACuriousMind can I have a gold badge for largest number of indices on a single object?

ACuriousMind

@0celo7 I refuse to give any appreciation for that :P

(also, I cannot grant badges, sadly)

Bernardo Meurer

12:17 AM

@HDE226868 If you'd like a soft introduction into Arch-like distros I recommend Antergos, it works very well.

If you're a Linux old-timer you can probably get Arch set up normally

or use Architect, it's a neat installer thingy

I do it manually because I like the struggle

0celo7

@ACuriousMind sadly?

whom would you grant a badge if you could?

Bernardo Meurer

Me, for helping others be more Free

Free as in Freedom

0celo7

Rebecca is still a Slave

you haven't helped her

Bernardo Meurer

She doesn't want to be freed

0celo7

that's a lie

Slereah

1:20 AM

hey hey

@0celo7 it's a lie group?

0celo7

oh screw you wolfram

Slereah

Filthy engie

HsMjstyMstdn

hahahaha I think I got that joke

0celo7

my \$150 calculator can't do $e^{i\phi}$

ACuriousMind

@0celo7 That's because money can only pay for real stuff :P

0celo7

1:32 AM

ohhhh, that's why money can't buy love or happiness

ACuriousMind

Precisely.

skull petrol

but it can rent it :P

0celo7

I'll mention that to reb the next time I spend money

HDE 226868

@BernardoMeurer I'll check it out, thanks.

skull petrol

Are you watching any of the madness? @HDE226868

HDE 226868

1:41 AM

@skullpetrol What madness in particular?

Today's been full of it for me.

skull petrol

March madness.

HDE 226868

Oh, yes. I had Villanova winning the whole thing.

Imagine my surprise last Saturday afternoon.

skull petrol

Me too.

HDE 226868

Oh, Oregon won. Good.

0celo7

I really don't understand the fascination with basketball

skull petrol

1:43 AM

Have you ever tried to play?

0celo7

^ accurate depiction of me

Bernardo Meurer

@0celo7 You're not that skinny

skull petrol

Ice T - Colors

►

^accurate depiction period.

0celo7

@BernardoMeurer proof?

@BernardoMeurer listening to quavo atm

$\sin(500\pi t+120^\circ)$

...what?

is the $500\pi t$ supposed to be in degrees or radians?

wtf is this

skull petrol

Convert the 120 degrees into radians.

ACuriousMind

1:52 AM

@0celo7 engineering

0celo7

@skullpetrol how?

skull petrol

-_-

0celo7

I'm going to avoid doing this now

@BernardoMeurer youtube.com/watch?v=bqlzoxTvOkE

I bet ACM can't watch :P

Where do they find these people for videos lol

Bernardo Meurer

The hell am I watching

I fucking hate Quavo

0celo7

good, popular music

@BernardoMeurer ...@ACuriousMind take him out

Bernardo Meurer

1:58 AM

Did this fucker eat T-Pain or something?

Goddamn auto-tune

0celo7

> He prolly think it's a club light
But really it's the red dot
- Quavo

ACuriousMind

@0celo7 The GEMA actually settled their beef with YouTube a few months ago, many of what was blocked is now accessible without proxies

@BernardoMeurer language :P

0celo7

Quavo has always used a crapload of autotune

Bernardo Meurer

@ACuriousMind Sorry, I just really hate Quavo

Don't watch.

2:00 AM

This is real good music

MOTHER

actually not much autotune in this one

@ACuriousMind can you please control his language :(

Bernardo Meurer

I'm just singing the lyrics :(

@ACuriousMind Did you have a chance to listen to Idles?

They're p good

0celo7

Travis Scott - Oh My Dis Side feat Quavo (Music Video)

►

@BernardoMeurer One of Fantano's favorite songs

it's so very good

ACuriousMind

2:02 AM

@BernardoMeurer I...do not recall anything called Idles

Bernardo Meurer

@ACuriousMind Check the video up there, they're a british punk band

skull petrol

Punk is dead.

0celo7

@BernardoMeurer tbh I don't know why Quavo is so popular, Takeoff and Offset are better

@BernardoMeurer why do you like this song

it's a dude screaming, his voice isn't pleasing

the instumental is ok

Bernardo Meurer

Because the drums are tight af

and also

MOTHER

FUC*ER

skull petrol

Does anyone wear FCUK?

0celo7

2:14 AM

@BernardoMeurer have you listened to youtube.com/watch?v=K44j-sb1SRY ?

lil yachty's finest song

ACuriousMind

@BernardoMeurer Not really to my liking, I'm afraid

OBE

how do you theoretically describe superfluid fountain effect using QFT or whatever it used to describe it?

Bernardo Meurer

@ACuriousMind A shame

OBE

every book I read skips this part about how the fountain effect works.

ACuriousMind

@OBE 1. Typing that into Google I find several papers explaining it for a simple Bose-Einstein condensate. 2. It's very possible that there is no current theoretical explanation for it for an actual superfluid, since I think we don't really know how exactly superfluidity works except that it's related to B-E condensation. 3. You might want to ask this on the site so an actual condensed matter theorist might see it.

OBE

2:28 AM

I'll just google it and read the papers thanks acm.

0celo7

Oh my god

OBE

I forgot to do that

0celo7

Yosida doesn't assume neighborhoods are open

what the hell is this

ACuriousMind

@OBE ?!?!!?!?!?!!?!!??!!!??!?!??

:P

0celo7

you broke him!

@ACuriousMind Interesting fact, if $L^p\ni f_n\to f$ pointwise, then if $||f_n||\to ||f||$, we have $f_n\to f$ in $L^p$

OBE

2:31 AM

@ACuriousMind this paper by karpiuk has what I want. and yeah idk why I forgot to do that.

0celo7

Seems strange because convergence of norms is so weak

OBE

ughhh

i need to get good

0celo7

about?

@OBE how much analysis do you know?

OBE

2:53 AM

not enough

i stopped focusing on it

i will start again soon

Slereah

There's a formula for computing PDEs on covering spaces from the normal space

I wonder if it's also valid for covering spaces of timelike homotopies

0celo7

@Slereah what does it mean to "compute a PDE"

Slereah

well the specific paper is about calculating propagators of quantum theories on multiply connected spaces

0celo7

@OBE Here's a problem I solved on an exam: Let $f:\Bbb R^d\to\Bbb R^d$ have the form $f(x)=x+\phi(x)$, where $\phi:\Bbb R^d\to\Bbb R^d$ is Lipschitz with constant $<1$. Show that $f$ is a bi-Lipschitz homeomorphism.

Replace $\Bbb R^d$ with a Banach space $E$ for fun.

Slereah

I should sort my papers again

They're kind of a mess

I guess that the break in the Cauchy problem comes from the fact that for a lot of universal covers of spacetimes with CTCs has singularities

0celo7

3:11 AM

Hmm, if I have an $x'\in X'$, can I find $x\in X$ with $||x||=1$ and $|\langle x',x\rangle|\ge 1/2$?

$X$ is a normed vector space

I think I want $||x'||=1$.

Then it's clear by definition of $||\cdot||$ for $X'$.

@Slereah Suppose I have a separable metric space $X$. Is a subspace $Y$ also separable?

Slereah

I do not know

0celo7

Seems like it should be...but the countable subset of $X$ need not intersect $Y$.

ACuriousMind

0

Q: Quantum physics is making me depressed?

I know this seems bizarre, but QM makes me feel really depressed. It makes me depressed because it shows us that nothing is really real, and that everything is just probability. Does anyone else feel this way? It just seems that the world is so bleek

quantum-mechanics

Slereah

lel

ACuriousMind

If someone has some comforting words for OP, feel free to add them :)

(nothing I could think of did not either sound condescending or cynical)

0celo7

3:17 AM

I left a comment.

Cows

Hey guys

Is there an article, book or text of some sort with detailed explanation of tricks like differentiating under the integral, Feynman parameterization etc and other black arts of calculus?

0celo7

Ah. A separable metric space is second-countable. The subspace inherits the second countability. Then apply Theorem 30.3 in Munkres.

Cows

the schwinger -feynman stuff. . .

0celo7

@ACuriousMind What happened to my comment?

Cows

....................

ACuriousMind

3:23 AM

@Cows ,,,,,,,,,,,,,,,,,,,,

Cows

I know qft books discuss this, but I was wondering if there were texts solely devoted to this

Do the math competition texts carry this type of knowledge?

I am curious about calculus texts that have these techniques discussed in them. The reason is that a while back, some people said i did not learn calculus because I was not aware of these things. What calculus texts have these?

0celo7

Cows

Did Feynman or Schwinger write calculus texts?

0celo7

there's your black magic calculus

Cows

hehehehe

ok give me a sec, let me think over the pictures. Give me about 3 minutes

0celo7

3:28 AM

10 internets points if you guess the book

Cows

is it a functional anal text of some sort?

0celo7

anal?

Cows

analysis

0celo7

It's more analysis of functions than functional analysis

Cows

Let me ask you something . .

So if I read soaked up that text, would it give me a natural understanding and intuition to understand the tricks I mentioned and potentially more?

0celo7

3:31 AM

no

Cows

hehe

0celo7

but you would learn some black magic calculus

Cows

I do want to learn black magic calculus

What is the name of the book?

0celo7

Sobolev Spaces by Adams and Fournier

Cows

looking it up now

0celo7

3:33 AM

It's on my shelf, good book

Cows

Looking through some of the pages(via amazon) It looks like a serious piece

Can you tell me how some of the information in the text has come handy in your area of research?

0celo7

@Cows first, chapter 2 is hands down the best reference for $L^p$ spaces

that + Lieb & Loss and you're pretty much good to go for those guys

chapters 3-6 are invaluable for PDE

I'm taking a break from that stuff and focusing on functional analysis right now

I want to have more functional analytic tools for PDE

spectral theory in particular

Cows

Is spectral theory important for people doing quantum mechanics?

0celo7

Not to most physicists I know, no

(I'm not a physicist)

Cows

I will get the book and hopefully look at it from time to time

0celo7

3:44 AM

lol don't get it

it's a very technical reference, not a textbook

if you want a textbook I can recommend something better

Cows

lol which one will you recommend?

0celo7

on the same topic?

what do you want to learn more about in analysis/geometry?

Cows

I want to learn more analysis. I also want to be able to calculate things

0celo7

well, what do you know already?

@Cows I'd try "Analysis" by Lieb and Loss

Cows

Well, I took the standard undergraduate calculus semesters, linear algebra, and differential equations. I self studied some real analysis. However, I have been looking at some of the techniques involved in doing Feynman integrals and noticing some tricks here and there, and wondering

looking it up now

0celo7

3:52 AM

it doesn't talk about Feynman diagrams

but it will put many things you know from quantum mechanics on a rigorous footing

Cows

It looks quite promising from the table of contents

0celo7

I hope to spend more time with it some day

chapters 9, 11, and 12 are fascinating

Cows

Those chapters contain physics , I see

0celo7

mathematical physics

Cows

I am going to go buy some food. I will be getting the text you mentioned for sure

0celo7

4:05 AM

nice!

bye, have fun

skill patrol

4:38 AM

fun?

0celo7

yes, fun

skill patrol

Is this your county?

0celo7

F is for fire that burns down the whole town!

U is for uranium... bombs!

N is for no survivors when you-

:(

it ends there

@skillpatrol oh my god lol

yeah it is

I'm off, cheerio.

skill patrol

Later pal.

Slereah

7:53 AM

Why are there so few acausal metrics in Stephani

Only Godel and Kerr

Slereah

8:22 AM

Why isn't $S^1$ a covering space of $S^1$?

Wouldn't the only connected component map itself diffeomorphically under the identity

Or is it a cover but not the ~universal~ cover

"Every space trivially covers itself."

Ah yes

skill patrol

8:43 AM

Have you seen this? @JohnRennie

John Rennie

That's fairly standard for press reporting.

skill patrol

Okay.

John Rennie

Lots of British people get murdered by other British people every year. That doesn't make the headlines because we all know it happens.

skill patrol

Right, right.

John Rennie

But when four people are murdered by a British person who happens to have been radicalised it's a big deal that the murderer is British. Oh well.

The worst mass murder in the UK was, I think, the Dunblane massacre and that murderer was British.

skill patrol

8:51 AM

\o @yuggib

yuggib

o/

skill patrol

Did you watch the Abel Prize presentation? @yuggib

yuggib

@skillpatrol no...who was awarded to?

skill patrol

A French guy working on wavelets.

Yves Meyer

Slereah

Wavelets, when will they learn

yuggib

8:59 AM

he's a quite known analyst yes

skill patrol

9:11 AM

abelprisen.no/artikkel/vis.html?tid=69572

Secret

9:58 AM

[Random]

> Of course, you can use Shelock Holmes in your story, because Shelock Holmes and Shelock Holmes are two different things

Hint: buffalo x 10

John Rennie

@skillpatrol I think this puts it very nicely

London in the grip of normality!

2

John Doe

10:31 AM

@ACuriousMind From our brief discussion yesterday...In Sakurai he gives the correlation amplitude as $$C(t) = \int dE |g(E)|^2 \rho(E) \text{exp}\big( \frac{-iEt}{\hbar} \big)$$
What is the effect on the correlation amplitude $C(t)$ for large $t$? I see how large $t$ implies that the integrand oscillates more as a function of $E$ but how does this imply that $C(t)$ decreases for large $t$, which is what I assume it does?

Secret

10:49 AM

[Scifi random fabricated dialogue]

> Sector G Project ### currently on pilot trial. Scale up planned in the coming future, assuming the future still exists

ACuriousMind

12:06 PM

@JohnDoe You can heuristically say that if $g$ and $\rho$ vary slowly, then $C(t)$ will be close to zero for large $t$ since the fast oscillation means that nearly the same values of $g$ and $\rho$ contribute to the integral both positively and negatively. Of course, you cannot say anything without knowing about $g$ and $\rho$.

o/

\o/

How are you doing?

@yuggib I don't understand what his work is about/why all the hype

@Slereah it is, but it's not a very good one

ACuriousMind

@Danu Quite well, how about you?

Slereah

12:09 PM

@0celo7 Please no value judgement of coverings

Danu

@ACuriousMind Pretty decent---had a really long, nice talk with my supervisor yesterday.

DanielSank

@Danu Those can be good or bad...

@ACuriousMind \o

Danu

@DanielSank Very good! He made it pretty clear that he's happy with where it's going so far (he mentioned we will probably write a paper after I finish my thesis).

DanielSank

If $\exp(i \omega t)$ is an "infinite rotini", is $\omega$ the sauce retention factor?

Danu

lolwat?

ACuriousMind

12:12 PM

@DanielSank o/

DanielSank

@Danu See star board...

@ACuriousMind You already \o/'d.

ACuriousMind

@DanielSank Oh, I see

I do not understand the intricacies of digital high-fiving, I will admit

DanielSank

@ACuriousMind You'll learn. It's easier than QFT.

Danu

I saw it more as a waving hand rather than a high five. Oh well...

ACuriousMind

(where digital means "on the 'net", not "with a finger" :P)

DanielSank

12:19 PM

@Danu Definitely a high five.

Whatever happened to Mafia?

0celo7

Deleted his account after being called a Nazi on meta.

DanielSank

@0celo7 o_O

Why do people delete their accounts?

What's wrong with just not coming to the site for a while?

When I get irked I just don't show up.

0celo7

I don't know. Maybe they think it's a protest or whatever, but the mods don't care.

DanielSank

@0celo7 What does what the mods think matter?

0celo7

I deleted my account, that'll show em!

DanielSank

12:21 PM

Show 'em what?

0celo7

@DanielSank because who else would they be protesting

DanielSank

Who's "em"?

@0celo7 Presumably whoever called him a Nazi...

0celo7

I don't know! That's the point

DanielSank

Speaking of which, I played a game called "Secret Hitler" last night.

It was interesting.

0celo7

@DanielSank that person probably has long forgotten about this

DanielSank

12:22 PM

@0celo7 Right.

So deleting your account is dumb.

0celo7

That's my point, were agreeing.

Danu

@0celo7 By whom?

0celo7

Just like how 2017 is threatening to delete his account. I chuckled for a second then moved on. He's not irking anyone by doing it

Danu

Gorillaz - Saturnz Barz (Spirit House) 360

►

0celo7

It's pointless

Danu

12:23 PM

This is an interesting idea

0celo7

@Danu I don't know, not a chat regular.

You can find it via careful inspection of Meta

Key word "Goebbels"

DanielSank

@0celo7 It irked me. I don't like it when people reason as follows: "This resource is useful, but people aren't using it how I want. Therefore, I will never use it again."

^ Dumb

Danu

lol

John Rennie

@Danu Damon Albarn was on BBC Radio 1 last night talking about the new album.

DanielSank

ok gotta go

0celo7

12:25 PM

@DanielSank let me rephrase. It didn't irk the people who upset him or have the power to fix things.

DanielSank

ciao, everybody

@0celo7 We all have the power to fix things.

0celo7

You don't have the power to bring back Chris

If you do, then you should do that.

Danu

@JohnRennie Ah, really? A lot of stuff leaked recently, I guess it was part of the promotional campaign. I must say that what I've heard doesn't sound all that interesting.

0celo7

@JohnRennie can I haz donation plz

John Rennie

@Danu I guess Damon Albarn is at the point where he now does what he wants without worrying too much about what anyone else thinks. He was on good form when interviewed last night. Very lively and entertaining.

Danu

12:28 PM

I can imagine. Must be nice to be in such a place.

John Rennie

@0celo7 you've already got a laptop. I only give away laptops.

@Danu They played a couple of tracks from the new album and my initial reaction was yes it's OK but not great.

0celo7

@JohnRennie but this is much cheaper and is about a ball :)

Danu

@JohnRennie Yeah, same for me.

Secret

12:40 PM

How to hack and cripple predatory journals, Give them something equally fake

John Doe

12:53 PM

@ACuriousMind Okay but my problem is, and I know this is wrong I just don't know why, the sin and cos functions integrate to zero on average since they go above and below zero as they oscillate. So doesn't $g$ and $\rho$ just act as a amplitude (or something that modulates the amplitude) but still $C(t)$ is zero on average?

@ACuriousMind Oh you are saying that if we have a spike in $g \rho$ then say the positive part could contibute more to the integral?

Yashas Samaga

0

Q: How Einstein got the first idea for special relativity?

I am reading Big Bang by Simon Singh. Here is the short story (as I understood it): Einstein gets a contradiction by assuming that 1- The speed of light $c$ is constant with respect the ether. 2- Galilean relativity is true. because if you were traveling at the speed of light, you wouldn't be...

special-relativity speed-of-light

primarily opinion based?

Transcript for