The h Bar

Obliv

20:00

I don't see what's so interesting about them. It's just a phenomena when two waves moving in opposite directions constructively interfere 1:1.

OOOOH GUyS IT loOKs like iTS stAnDing stIL!!1!

user116211

@Obliv Do some home experiments prescribed by Crawford in his book when you have time; they are exciting.

Sanya

@Obliv I was being sarcastic ;)

Obliv

@sanya I know lol

user218912

$$\left[\int d^3x\, \bigg[ \int d^3k [a_k e^{-ik \cdot x} + a_k^\dagger e^{-ik\cdot x}]\bigg] e^{x^2/a^2}\right]^2\,.$$ @Sanya

Obliv

@mafia Are you being genuine? I don't know man it would take a lot to make me interested in experimentation.

user116211

20:03

@Obliv What? What do you mean by genuine?

Obliv

as opposed to sarcastic'

user116211

@Obliv when you have time

user116211

And okay.... if you like interesting experiments .

Sanya

@IceLord hmm ... we use spherical coordinates, we can express $k \cdot x = k x \cos ( \vartheta )$, we integrate out the angular coordinates, then we probably need to complete the square to do the gaußian

that would be my first idea

don't know if it'll work

user218912

oh I forgot spherical coordinates.

user218912

20:04

okay I'll try that.

0celo7

@IceLord lol

user218912

@0celo7 what?

0celo7

that's a hard ass integral

user218912

is it trivial?

user218912

oh

0celo7

20:05

no

Sanya

why does chat display too much rep for me :O

user218912

i know my message lagged.

user116211

@Sanya Your total SE rep.

user218912

@0celo7 ikr and we only have 1 week to do 6 similar problems.

user218912

fml.

0celo7

20:07

lol

Sanya

@MAFIA36790 ah ok, thx

Obliv

@IceLord hey whats that dagger symbol? Is that a stirling approx?

user218912

@Obliv it's hermitian adjoint.

user116211

@Obliv You can use star too.

Obliv

it can be called conjugate too @iceL

user218912

20:09

@Obliv yeah but

user218912

it's also transpose

Obliv

so it's the adjoint of a linear operator of a complex hilbert space?

0celo7

yes

user218912

I think so.

Obliv

a hilbert space is just an infinite dimensional vector space that preserves inner product? anything else?

user218912

20:12

yes it has some important properties

user218912

like completeness

0celo7

prserves inner product?

what does that mean

user218912

he means its an inner product space.

0celo7

@IceLord what does that mean?

user218912

it's also defined as the space of square integrable functions which is a kind of hilbert space.

Obliv

20:14

inner product = dot product?

user218912

@Obliv basically

user218912

I think there are some distinctions

0celo7

there are many more inner products than just the dot product

Obliv

linear operator = linear mapping between two modules. module = additive abelian group?

0celo7

between modules?

that's not what a module is

user218912

20:15

@Obliv wow you could just say vector space.

Obliv

well modules are more general, no?

user218912

yes

Obliv

i'm just reading off wiki lol

@0celo7 what is it then

user218912

@knzhou hi do you have any idea how to do this integral? Sanya told me a method to do it but I haven't tried it completely yet, do you agree with that method?

user218912

17 mins ago, by IceLord

$$\left[\int d^3x\, \bigg[ \int d^3k [a_k e^{-ik \cdot x} + a_k^\dagger e^{-ik\cdot x}]\bigg] e^{x^2/a^2}\right]^2\,.$$ @Sanya

Sanya

20:21

oh wait, do you actually mean e^{x^2/a^2}?!

user218912

yes

Sanya

for a real?

user218912

a is real.

Sanya

forget what I said then I guess; my mistake

user218912

oh

user218912

20:22

:(

Sanya

looks divergent to me ...

Obliv

@iceL what part of that integral defines that it's in 6D?

user218912

@Obliv there is $d^3x$ and $d^3k$

user218912

$3 + 3 = 6$

Obliv

they just add?

user218912

20:24

kind of

Sanya

hey wait ... sorry, I'm tired ^^" I didn't see the k-integral at all

Obliv

i didn't notice the k either lol

Sanya

just forget anything I've said in the last half hour I'd guess

user218912

@Sanya xD

user218912

any idea now though?

user218912

20:25

I'm tired too I slept for 3 hours again only.

user218912

I am running on caffeine.

user218912

I feel like my brain is foggy.

0celo7

I think I cannot prove it using methods from KN

so my earlier proof was right

I think there's some typos in the world

what a sad day this is

user218912

for me too.

Obliv

@iceL why did u get 3 hrs of sleep

Sanya

20:33

@IceLord my idea now is "let's ask someone about it". I'm not even completely sure what an integral over the space of creation/annihilation operators should actually mean.

user218912

@Obliv because I was on my ipad drawing stuff until 3am and I had to wake up at 6am to commute to university since I went home yesterday.

Obliv

what were you drawing..

user218912

random blue shapes.

Obliv

wait i can already guess

@iceL img.wallpaperfolder.com/f/4757245ADB3F/… something like that

just blue versions of anything a normal person would draw

user218912

woah I am not that good.

user218912

20:35

I can only draw basic shapes.

Obliv

Yeah i think that was a picture anyway lol

user116211

WTH is that:

user116211

0

Q: Problem About Calculation of double Higgs production Cross Section (for gluon fusion) with FeynArts+FormCalc

I want to mention about my problem about FeynArts/FormCalc.I have tried to calculate LHC cross section for "gluon gluon -> H H" process at Standard Model. However, my result XS is quite different from the ones in the literature. I have no idea about this difference or where is the problem. I'm u...

user218912

and if I were to draw it it would be all blue, including a blue sunset.

user116211

I mean the quoted stuff is looking terrible.

Obliv

20:36

it'd just be a blue square

user218912

@Obliv different shades and tones of blue exist you know.

user218912

but basically yeah

Sanya

@MAFIA36790 lol, check my mathematica code

someone has to be a very good friend for me to go through that ordeal :D

Obliv

@mafia jesus that whole first block in the quotes is so messy

I didn't know latex went through quotes.

user218912

wait isn't one of the integrals just a gaussian?

user218912

20:44

or does that $a^2$ make it not gaussian

Sanya

e^{-x^2/a^2} would be a Gaußian

and then I think my idea from earlier still applies assuming we can commute the k- and x-integrations

0celo7

@Sanya no one uses the ß in English

Sanya

@0celo7 you're right, but I have a hard time not using it - I'm just too used to it

user218912

@Sanya yeah so is the integral of that $\sqrt{a^2 \pi}$?

Sanya

nah, because you've still got the other x dependences

sorry, gotta go

0celo7

20:49

oh my

user218912

yeah i know... just trying to make something out of it

0celo7

you can complete the square

thrice

then use Cauchy

user218912

you did it?

0celo7

thrice

no but I can see what's going on

user218912

hmm

user218912

20:50

can you show me how to complete the square once in this integral so i learn how to do it

user218912

i'll do the other ones myself

user218912

you said there is 3

Obliv

I like how a basic concept like completing the square makes its way into QFT integrals

Guess I better not forget how to do it then

0celo7

no I won't do high school algebra for you

user218912

fuck my life I forgot how to complete the square.

user218912

20:52

better search it up now i guess...

Obliv

LOL

Can you distribute the $e^{x^2 / a^2}$ to the inner integral @iceL

user218912

I think it's legal to do that

user218912

but idk why it would be useful

user218912

@0celo7 should I do that?

0celo7

yes

Obliv

20:55

Then I thought maybe you could distribute it over the two $a_ke$ terms and then you'll have $e^{x^2/a^2 - ikx}$ on both terms

0celo7

@Obliv good

Obliv

then complete the square?

user218912

@Obliv wow you're a natural at qft.

Obliv

in the exponent

0celo7

yes but three times

you need to expand the dot products first

then separate all the exponentials

then complete the square

then do all three spatial integrals

then then three momentum integrals...maybe

I think you can leave those

user218912

20:57

@0celo7 how can you complete the square if you separate all of them?

0celo7

think about it

user218912

I think I'm misunderstanding what you mean by separate.

0celo7

I mean separate them into three exponentials, one with the x terms, one with the y terms, etc.

user218912

oh like that, okay

Obliv

@0celo7 u mean the dot product between $a_k$ and e?

user218912

20:58

@Obliv no he means the dot product between $k$ and $x$

Obliv

oh thats a dot product.. yea ok makes sense..

user218912

they're 3-vectors.

0celo7

the integrals are hard btw

Obliv

You think I don't know that? I work with 12-vectors on a daily basis in my PhD calc class

user218912

I have a problem where I don't try things myself until someone tells me.

user218912

21:00

is there a disease for that?

Obliv

its called get a good nights rest

user218912

nah I do this a lot 0celo7 knows.

Obliv

you're probably just getting lazy

user218912

@Obliv but that too.

user218912

@Obliv maybe

Obliv

21:01

when you feel yourself getting lazy it's good to do something else maybe get some air, exercise

or pump yourself with more caffeine

until your eyes swell with blood and burst

user218912

I have manic laziness.

Obliv

@iceL You can tell it's laziness because if I offered $100 to every integral you solved you'd probably be more inclined to try everything

user218912

maybe.

Obliv

$1000?

user218912

idc about money but I would do it for contact lenses that would make everything appear blue but not tinted.

0celo7

21:05

a small loan of a million dollars @Obliv

Obliv

right, I forgot that the colour blue is for you what gold is to most people @iceL

@0celo7 but if you were awarded a million then you'd get lazy again like 20 integrals in

user116211

@Obliv Commies love red.

Obliv

you would get acclimated to the wealth pretty quickly

0celo7

I could blow through 20 in a day

Obliv

@0celo7 actually yeah me too.

@0celo7 what would you do with the money

user218912

21:09

@0celo7 depends on the integral...

0celo7

I mean 20 million

user218912

how?

Obliv

I think i'd get a private study in the mountains with a trapdoor and henchmen

0celo7

I'd buy a Bugatti

that's 2 mil right there

then an 18 million dollar mansion

user218912

and how would you sustain them?

user218912

21:11

you're forgetting insurance and taxes.

0celo7

well yeah

I'm saying 20 isn't a lot

user218912

more like buy a decent car and a 5mil mansion and put the rest in the bank and get interest.

0celo7

I have a decent car

user218912

what is it?

user116211

Ford?

0celo7

21:12

@MAFIA36790 wth no i'm not a redneck

user116211

Volks Wagen?

user218912

bmw?

0celo7

not a Kraut either

user218912

lol 0celo7...

user116211

Toyota?

user116211

21:13

Audi?

user116211

Chevy?

user218912

user218912

@0celo7's car

Obliv

lool @iceL

@0celo7 dude why would you spend 2 mil on a bugatti when you can get a tesla that's faster & more amazing

0celo7

Ace Hood - Bugatti (Explicit) ft. Future, Rick Ross

►

user116211

21:23

@Obliv Tesla has no future.

user218912

@MAFIA36790 what...

Obliv

A car model that runs on a fuel that will be accessible to everyone for the next few billion years has no future? @mafia proof needed

user116211

> they are far more expensive to operate than are gasoline engines, at least if you include the battery replacement costs. Tesla includes the first replacement "free", but at the price they are charging for the car, it is (of course) you who are paying for it. Musk keeps hoping the price of batteries will drop, and they have a bit, but not as much as needed to make electric cars competitive with gasoline.

user116211

Read Richard Muller's view on Tesla: quora.com/…

Obliv

Yeah but gasoline literally has no future >100 years from now

user116211

21:28

@Obliv And Tesla is solution to it?

Obliv

yes, what is the solution to a depleting energy source besides finding alternatives

and if anything tesla is getting cheaper and more mainstream

0celo7

with any luck Hillary will get us into a war with Russia and none of us will be around to have to think about it

user116211

@0celo7 Trump will win; don't worry.

Obliv

@mafia i don't know much about it, but I heard the model 3 is really cheap ~35k (at least relative to the other tesla cars)

user116211

For an impartial discussion: quora.com/…

Obliv

21:35

@mafia wow I didn't know that solar thermal plants would be placed in deserts :O that's pretty cool

probably the cheapest & most efficient place to put one

0celo7

21:50

ok people

I need to compute $$\lim_{t\to 0}\frac{1}{t}[B^\ast -(\mathrm{Fl}^{A^\ast}_t)_\ast B^\ast]$$

Will give money for correct solutions

@BernardMeurer I want to help you with math

I don't want to do my math

Bernard Meurer

@0celo7 Lol then go read on how the karnaugh map forms a toroid

0celo7

link?

Bernard Meurer

Karnaugh map

The Karnaugh map, also known as the K-map, is a method to simplify boolean algebra expressions. Maurice Karnaugh introduced it in 1953 as a refinement of Edward Veitch's 1952 Veitch diagram. The Karnaugh map reduces the need for extensive calculations by taking advantage of humans' pattern-recognition capability. It also permits the rapid identification and elimination of potential race conditions. The required boolean results are transferred from a truth table onto a two-dimensional grid where the cells are ordered in Gray code, and each cell position represents one combination of input conditions...

Obliv

22:06

@bernard did u try working through examples

or were u given any

Bernard Meurer

@Obliv Wat?

Obliv

@bernard on how the grid is drawn as a torus

0celo7

ok that has nothing to do with manifolds

Bernard Meurer

@Obliv I can clearly see why it is a torus

I just want to know if I could treat it as a manifold since I can draw it as a torus

0celo7

DJ Khaled "Out Here Grindin" Official Video

►

@BernardMeurer OLD Khalidius

Obliv

22:14

@bernard so you want to treat the grid values as a set that is locally homeomorphic to euclidean space? why

user116211

@0celo7 Damn; I need money to buy books but that is beyond my scope T__T

0celo7

dat production quality

DanielSank

Julieta Venegas y Bajo fondo - Pa' Bailar

►

Obliv

crap gotta get to class have an experiment

Bernard Meurer

@DanielSank I still don't like spanish

0celo7

22:17

ok

after 6 hours of hard work

I have confirmed there is a typo in TWO books

and Wiki

user116211

2

Q: How does a superposition work with the cNOT quantum gate?

Note: In this question I am going to list the inputs in the order of control and then target. Using the cNOT gate, what would happen in the following scenarios (i.e., what would the outputs be): Input a superposition (all superpostions assumed to be of the form $\alpha |00\rangle + \beta |01\r...

quantum-information quantum-computer logic-gates

user116211

Homework?

Bernard Meurer

@MAFIA36790 She's in middle school

user116211

So?

Bernard Meurer

@MAFIA36790 Not even my chemistry teacher would do that

user116211

22:20

@BernardMeurer What are you saying? I'm not getting how it is related to being homework ;P

0celo7

@BernardMeurer the homework close reason has nothing to do with homework

user116211

Ah! So, @Bernard, are you taking homework in the literal sense?

Bernard Meurer

@0celo7 Ah, I thought it meant the user just wanted ppl to do their hoemwork for them

user116211

It's not how it means here.

0celo7

no

it's "homework like" questions

rob

22:23

Though note that "do my homework for me" questions fall under the mantle of "homework-like."

0celo7

yes

DanielSank

@BernardMeurer Yeah well, you're a dummy

user116211

@DanielSank o/

Bernard Meurer

@DanielSank Love you

user116211

Anyways, it's 3: 55 am; done my job of reviewing; also completed Lanczos; looked into Kelley; hmm... well, let me call it a day.

Bernard Meurer

22:26

@rob Hey

user116211

Good night comrades.

Bernard Meurer

@MAFIA36790 Bloody communist

user116211

@BernardMeurer No ;/

Bernard Meurer

@MAFIA36790 Comrade :p

user116211

Damn commies T__T

Bernard Meurer

22:27

Comrade

The term comrade is used to mean "friend", "mate", "colleague", or "ally", and derives from the Iberian Romance language term camarada, literally meaning "chamber mate", from Latin camera "chamber" or "room". A political use of the term was inspired by the French Revolution, after which it grew into a form of address between socialists and workers. Ever since the Russian Revolution, popular media in the Western World have often associated it with Communism. == Background == Upon abolishing the titles of nobility in France, and the terms monsieur and madame (literally, "my lord" and "my lady"),...

It actually says it's for communists lol

0celo7

22:38

$\mathfrak H$

DanielSank

@MAFIA36790 \o

0celo7

23:13

aha apparently the projection onto a coset is an open map!

good to know

Transcript for