@Slereah why would anyone do that?

@Slereah that's in Yosida's book if I recall correctly.

Well it's a QFT paper sort of

QFT tends to use +---

But why

It makes less stray - signs overall

you can just define $p^2 = m^2$

"Starting with the Poisson algebra $\mathfrak F_{\mu c}$"

how fancy

Oh no

he's doing deformation quantization

$$(F \star G) (\phi) = \sum_{n=0}^\infty \frac{\hbar^n}{n!} \langle F^{(n)}(\phi), (\frac{i}{2} \Delta_S)^{\otimes n} G^{(n)}(\phi) \rangle$$

The horror

Ok I have all of my stuff in the new apartment

Finally

Only took two days

Too many fucking books

How many QM formalisms are there, anyway

There's Heisenberg, Schroedinger, path integral, deformation, stochastic, Bohm

I forget what else

@Slereah no, there is simply noncommutative probability with random variables satisfying canonical (anti)commutation relations

colorado.edu/physics/phys5250/phys5250_fa15/lectureNotes/…

one theory

that's the list

@yuggib Yes, they are all equivalent, I know :p

Doesn't mean they are the same formalism

Lagrangian and Hamiltonian mechanics aren't the same, either

redefining an apple to be named orange does not change the substance you know

Well yes, except it's not an apple

It's a theory

the way you define it is pretty important

That's like saying C and Python are the same because they're both Turing complete

in fact there is only one way of defining a theory properly, the rest is just words

the Craig axiomatization, yes :p

Except of course the Bohm theory and the Schrodinger theory don't predict the same results for all cases

none of them are, strictly speaking, completely equivalent (because some of them are neither properly-defined theories)

I don't think any of them are properly defined for any real cases, really

for example, the automorphisms of the algebra of observables and of the space of states don't share equivalent regularity properties

so even Schrödinger and Heisenberg are not completely equivalent apart from special cases

btw

Do you know an example of this

Non-continuous representations of the Weyl algebra

@Slereah representations of what?

Weyl algebra

of finite degrees of freedom

of course if you don't require continuity, or that they are set in Hilbert spaces, there are many more representations

@Kaumudi.H if you're concerned I might be going senile then I'm afraid you're already far too late :-)

Well yes, but which!

you can construct infinitely many

Then surely making one would be easy

fix a setting...do you want the representation to be set on a linear space, and consisting of linear transformations?

For instance, yes

let $V$ be a linear space, $L(V)$ the set of its linear maps

@Kaumudi.H I do actually have a very good reason for buying that laptop. I need a laptop with a 17" screen for working away from home. I have got one laptop like that, but I hate the keyboard on it. The laptop I've just bought has a much nicer keyboard.

there are infinitely many maps $H(X,\sigma)\to L(V)$ that associate to any element of the Heisenberg group $H(X,\sigma)$ an element of $L(V)$

i.e. that map an element of $\xi\in X\times \mathbb{R}$ to a transformation $U(\xi)\in L(V)$.

@Kaumudi.H It really isn't that much money. It's not as though I'm jeopardising my future prosperity by buying it. If I had taken to buying Ferraris that would be a different matter :-)

now require that for any $\xi_1,\xi_2\in H(X,\sigma)$, $U(\xi_1\xi_2^{-1})=U(\xi_1)\circ U(\xi_2)^{-1}$

If you want to do it discontinuously, I suppose you can set $U(\xi)=1$ for any $\xi=(x,\lambda)$, $x\neq 0$ or $\lambda\in \mathbb{R}\setminus \mathbb{Q}$, and $U(0,\lambda)=i\lambda$ for $\lambda\in \mathbb{Q}$. Then this should be a representation, and it is discontinuous when you endow $L(V)$ e.g. with the topology of simple convergence (or better suppose that $V$ is normed and endow it with the uniform operator topology).

@Kaumudi.H Is the headphone jack still not working?

If you plug in the headphones and wiggle the plug do you get bursts of sound, or just nothing.

Does the sound play through the laptop speakers when the headphones aren't plugged in?

$U(0,\lambda)=e^{i\lambda}$ I meant to say

@Kaumudi.H Ah, OK, if inserting the plug isn't turning off the main speakers the headphone jack is definitely knackered,

@Slereah (Having looked at the author list) I've been using Dan Styer's incomplete notes on statistical mechanics as the basis of my thermal physics class this semester, in part because he is able to present a clear point of view at multiple levels of detail.

So seeing his name on a document is pretty much a recommendation in my view.

@Kaumudi.H well it's not a huge investment ...

Unfortunately the notes are quite incomplete in places and I've ended up writing upwards of sixty pages of additional material to try to make the onnections.

On the up-side that has forced me to think carefully about a number of things I'd taken for granted before.

It is true what they say about teaching being the best way to learn.

@Kaumudi.H If you want really good sound and you're prepared to pay a bit more you can buy a DAC. @Bernardo would be the best person to advise on this as he's looked into headphone DACs for his laptop. But they are more like £50 so that is quite a lot of money.

This sort of thing

The Dragonfly is a very well regarded reasonably priced DAC.

DAC being digital to analogue converter

Wait, that maybe does not work because the sum of rational and irrational is irrational

Well the Dragonfly is top end of the budget DACs. Bernardo was looking at one about half the price.

But you're talking serious audiophile quality with these DACS. Substantially better than the audio circuitry built into the laptop.

@Kaumudi.H a cheapo adaptor it is then :-)

heya

What's up

Did anyone mension digital audio? :)

@JohnRennie Do you like Sex Pistols?

Kaumudi needs a cheap headphone DAC.

Why? Is the one on her laptop not good?

The one on my dell works pretty well

@BernardoMeurer the headphone jack is bust

anyways there should be such an example that works

Oh, I see

Well, there are so really cheapo USB dacs out there

If she doesn't care for audio quality, that'd be my go-to

amazon.com/D03K-Digital-Analog-Audio-Converter/dp/B009346RSS/…

@BernardoMeurer the Sex Pistols are a really underrated band. Everyone remembers the publicity stunts, but people forget just how good the early tracks were. Everyone should have Never Mind the Bollocks in their record collection!

This is probably good enough :)

@JohnRennie Yeah, I just got Never mind the bollocks, listening to it right now

on IEMs, nto speakers though

WAIT

The one I sent doesn't have USB

amazon.com/K1-Portable-Headphone-Amplifier-Titanium/dp/…

Bingo

I have Fiio stuff, it's great

@Kaumudi.H This is probably the best cheap option

@Kaumudi.H Yes

Fiio is a really nice company in my experience

fiio.net/en/products/39

I own this

2700 moneys isn't bad

And it's a nice price/quality compromise

who needs a headphone. play it freakin loud

anything under that and you'll either be building it yourself or getting a really crappy DAC

@BalarkaSen Laptop speakers don't go loud

boo sorry bout that

@BalarkaSen you don't necessarily want your parents to hear what you're listening to :-)

@Kaumudi.H Oh if only I told you how much I spend in audio :P

@Kaumudi.H I'd buy a cheapo adaptor like the ones we looked at. Then if you decide music really matters to you save up for a Dragonfly or the better quality FiiO DACs.

Dragonfly is OP

@JohnRennie I wonder if I should play it loud, and tell the gathering neighbors that I was just listening to Beethoven's 9th symphony.

If she doesn't have good cans shelling 100 bucks into a dragonfly won't do her much good

IMO

True

@BernardoMeurer have you seen what I've just bought?

a@JohnRennie DAAAAAAYUM

Badass

Kepler GPU

sweet

Actually it's only the same CPU power as yours :-)

But it has a 17" screen which I need when working away from home.

I like how these precision laptops look like bricks of death

It's stylish

They're massive, and bloody heavy.

But that's OK - I won't be carrying it around much.

@JohnRennie A shame a beauty like that will be running PROPRIETARY MALWARE

@Kaumudi.H picture? :-)

Fuck man, I hate these IEMs :(

Money to waste, never again

@BernardoMeurer Windows 10 :-) Oh well ...

IEM?

In-ear monitor

Ah. I'm with you on that. Wherever possible I use over ear cans.

And these are really good ones

But they just don't fit my ear

I have over-the ear headphones, but they're massive, and open-back, so using them on-the-go is not an option

@Kaumudi.H That's your dinner?

A puri with chick peas?

John knows it

looks more like some evening snack :P

Ah finally found the video I was referring to

That looks like a really nice starter. What are you having for the main course? :-)

looks more like chappati

you use plates made out of dry leaves?!

when you go out to eat at a cheap place yeah

Stop with the food

A certain someone convinced me to go on a diet with her

now my life sucks

convince her that you don't need no diets!

@Avantgarde Not worth the struggle

see yiu Kaumudi

you*

@JohnRennie Do you like Blue and/or R&B?

@BernardoMeurer Blues not so much. It all sounds like old men wailing to me.

R&B yes because it has some life to it.

@BernardoMeurer I saw these guys at Glastonbury in 1985 and it was absolutely awesome - a fantastic gig. Despite the name they're R&B not Delta type blues.

@JohnRennie Have you heard of Michael Kiwanuka?

It's a nice Rock/R&B mix

I have his album if you want it

in FLAC

i'll resell it to you for 1 cent (not piracy!)

lol

@BernardoMeurer I've heard of him and I've heard his singles on the radio. I don't have the album. If you wanted to mail me a link on Facebook I'd be interested to have a listen through.

I think I'm going to cue up Never Mind the Bollocks!

@JohnRennie Uploading it :)

How are you getting on with the replication app?

@JohnRennie Paused to work on my Programming final project :/

It was going well though, Rust is nice

Quirky, but nice

@Kaumudi.H it looked really nice. I'm a big fan of chickpeas in chole or channa masala.

@JohnRennie mega.nz/#!FfZSjASI!rqevlDdUD2K0PSR2Fyz7TSO2FuwvzxOesmx7aOHz9lU

@JohnRennie tell me when you download

Old place cleaned

Or rather, click

Have to check out

Almost done moving

@BernardoMeurer will do.

@Kaumudi.H I wasn't sure what the other items were - aprt from rice of course though I didn't realise it was coriander rice.

@BernardoMeurer Done, thanks :-)

@JohnRennie Delete the message with the link please :)

Is the download completed?

@BernardoMeurer finished yes. I can only move the post to Trash, where it will still be visible. Only a mod can delete the message completely. I'll move it to trash it if you want.

@Kaumudi.H Tamarind rice?

@JohnRennie Leave it here then, I'll delete the file :)

@JohnRennie Done, link should be dead now

@BernardoMeurer yes.

I've been toying with open a Mega account. What is their app like? Does it do directory synchronisation?

@Kaumudi.H Too much is ... just right :-)

@JohnRennie Not sure, I just use it for sporadic file drop-offs

I'm impressed, John. You know Indian food pretty well.

@Avantgarde My father was based on the North West frontier during the second world war and he learned to cook Indian food there. We used to eat Indian food a lot when I was a child.

and home

@JohnRennie Oh wow, I see. That's a nice story to tell

@Kaumudi.H No. In fact most Indian restaurants in the UK are run by people from the North so it's quite rare to get South India cooking in the UK.

He must've had idli sambar, at least

@Avantgarde I think all regions have their own version of a vegetable curry that is more or less like sambar.

kind of, yeah

However I have never eaten idlis.

Idlis are nice

@Kaumudi.H No. I've never eaten dosa. Obviously I've eaten pancakes made from wheat flour, but not from rice flour.

Charming :-)

haha I can imagine

It's a bit hard getting a good picture of QFT in curved spacetime because a lot of authors use different methods

At least the vomit will be nice and white :-)

They are all equivalent to some degree because they're all Haag's axioms + GR + wavefront sets

But it's a bit hard to get an idea of the constructive method to do it

@Kaumudi.H naan is definitely my favourite Indian bread.

Oh my god John

NaN bread

@Slereah Each author has their own way of presenting material ;) I guess that's a con of having superfluous resources to study from

Oh it's not even the way of presenting

they are actual different constructions

Some will do it as Borscher algebras

others as deformation quantization

Some just keep everything abstract

@Kaumudi.H 20! I don't think I could eat 20 pancakes ...

@Slereah That's confusing. Are you studying from a review or the actual old papers?

I've never had that pancake which people eat for breakfast. The one where you put honey

From several old papers

you see, the problem is

Idlis do not have any taste whatsoever. They should put stuff inside idlis

AQFT is defined as a functor

The actual implementation of it is left undefined

you can implement it several ways

as long as it obeys a set of various axioms

@Avantgarde in the UK we call those Scotch pancakes or drop scones. They are made with self raising flour so they fluff up lie a cake.

In the UK pancakes normally mean unleavened pancakes.

That still doesn't produce any taste in the core

@BalarkaSen presumably they are eaten for their texture then?

@BalarkaSen Nothing produces taste in my core.

@JohnRennie yeah, I see the pic. I have to try those someday

I am sure it can be made an excellent dish with severe modifications

@Avantgarde they are very easy to make. Just mix self raising flour, an egg and milk to make a thick batter and fry it. I used to make them a lot as a student because they are so easy to make.

That's why they are served with sambar, chutney, etc

@ACuriousMind It's lucky that no-one has plans to eat you then :-)

@JohnRennie That's easy stuff. What do they go with, apart from honey? Are they eaten without any additional stuff too?

@ACuriousMind I am sorry for you.

@Avantgarde anything. They work well with both sweet and savoury food. They are very nice with bacon.

@JohnRennie That's...reassuring.

fricassée of string theorist :-)

Nice flavour, but the meat can be a bit ... stringy!

I resisted making the rubbish joke for several seconds. I hope you're all impressed.

Maybe I should become a "Mmmmmmmh"-theorist :P

I believed for a very long time that 'smh' meant "so much hate".

It's OK. I Googled SMH and found out what it means :-)

kids these days

But why would you want to Suck My Horse?

ktd

SMHS - the last S stands for Sadly

@JohnRennie I see. Didn't know they went with bacon too

why am I watching a video of William S. Burroughs shooting a portrait of Shakespeare

@JohnRennie can electrons execute SHM

which is another thing I have to try someday

@RishiKakkar you get simple harmonic motion when there is a quadratic potential i.e. the potential depends on $x^2$. Offhand I can't think of an example of electrons in such a potential.

@JohnRennie

I need C help :P

@Kaumudi.H i have no idea how to respond to that.

@BernardoMeurer What's up?

urban dictionary is the best

dmckee is around as well if you need a C guru

haha the first definition of physics on urbandictionary is nice

@JohnRennie I have this code:

gist.github.com/bemeurer/d55a259409ee408baa81b688ae3ea888

OK?

it's good for laughs

@JohnRennie one day when i was looking up the some of the red dust came it wasn't bricks but something i didn't understand what was it

@JohnRennie It terminates with a SIGSEGV

This is the valgrind log

gist.github.com/bemeurer/290b1048f3cf90f5c91b12e2a31f3416

Where am I screwing up?

@BalarkaSen That's your personal problem.

Now I will inevitably look

@Kaumudi.H Audio people

@ACuriousMind A wise man once said always spread your personal problems to the greater mass of people

To anyone who claims that physics is ugly, irrelevent, or that the world would be better off without it, who do you think invented the silicon chip? An arts student?

lol Balarka

I don't think anyone like that is here

That's the purpose of moaning on toothaches - The Underground Man

He only cares about the GDP

@Slereah It's a Marxist-Leninist idea

@RishiKakkar chemists?

@BernardoMeurer I've just built it on MSVC and it crashes here too. Finding the cause of the crash will take a while though ...

capitalism dissolves, bringing isolated human problems into the collective humanitarian issues

Marxist leninists were pretty fine with physics

A lot of fine soviet physicists

@JohnRennie It's such a s imple code

well you need bombs man

bombs need physics

I'm certain it's a small mistake in allocation

Or something like that

@Kaumudi.H I had to read that a few times to realize what he was actually trying to say, too, you're not alone.

In Soviet Russia, you don't study physics, physics studies you

@BernardoMeurer I'll run it through the debugger if I can remember the MSVC flags for a debug build ...

The Soviet Union also did a lot of work on fundamental physics

@ACuriousMind @Kaumudi.H Plebs

oops, that's my fault :-)

Have you got the data file it uses?

@JohnRennie yeah, lemme give you a gist for it

gist.github.com/bemeurer/b7fc45a4640b52e1a9cf029919ef7f30

@JohnRennie I thought the :-O was fully appropriate there :P

There you go

@BernardoMeurer Why would you not say "lemme give you the gist of it"?

@ACuriousMind because I don't like to sound smart