The h Bar

9:00 PM

@0celo7 Do you note how I carefully avoided making a political statement there to not start another politics debate, and how just tried to provoke one?

Danu

Anyways @DanielSank it has been a fun discussion. It's funny because I usually argue your POV against all my friends :)

0celo7

>friends

Danu

→ 2 messages moved to Trash

ACuriousMind

wtf is a "shitpost". I've seen a lot of shit posts and these messages don't even come close

0celo7

@ACuriousMind lurk moar

Bernard Meurer

9:00 PM

@Danu That last one is took me a while to make dawg!

DanielSank

@Danu A man after my own heart.

Bernard Meurer

Europeans all love their censorship

Danu

Reservoir Dogs - Mr. Pink - World's smallest violin

►

DanielSank

@ACuriousMind I'm terrified by the notion of comparing you to either.

Bernard Meurer

Pretty cool

user218912

9:02 PM

yes

Danu

→ 6 messages moved to Trash

DanielSank

:32698207 You're the hero hbar needs, but doesn't deserve.

Awwww, dangit.

user218912

why are you cleaning up the shitposts? @Danu

Danu

Hi @AlfredCentauri (hope you didn't mind my ping)

Bernard Meurer

@Danu For sucks sake danu what's wrong with saying the word shitpost?

Danu

9:03 PM

@BernardMeurer Da clutter

DanielSank

So how come the chatjax link doesn't work any more?

dl.dropboxusercontent.com/u/78279253/mathjax.html

Danu

Hi @rob also

Bernard Meurer

@Danu Come on man that's totally arbitrary

You shouldn't just go around deleting stuff because you feel like it

DanielSank

My browser wants to download the HTML when I click, instead of going to the page.

Alfred Centauri

@Danu Hi Danu

0celo7

9:04 PM

interesting

Bernard Meurer

@DanielSank Hmm. Works here if I bookmark it

0celo7

moving shitposts to the trash does not remove them from the star wall

user218912

@0celo7 reload the page.

Danu

@AlfredCentauri Excited for the election? :)

Slereah

I think the point of asymptotic numbers is that you can write them as Taylor series

0celo7

9:04 PM

oh my god this chat right now

sensory overload

DanielSank

@Danu I keep thinking "I should have run", and then I remember all the reasons I didn't :P

Bernard Meurer

@Danu Sure, okay then, guess we don't discuss moderation

Slereah

Like $\forall \xi \in \ ^\rho\Bbb R. \xi = \sum_n a_n \rho^n$

Danu

@DanielSank I also had a small existential crisis 20 minutes before the end of the nomination period.

0celo7

ah, ok, it's in Jost

DanielSank

9:05 PM

@Danu Exactly.

Alfred Centauri

@Danu I've been working QFT problems all day and so I'm well past the point of feeling any emotion whatsoever. I just discovered the election is open that there is another candidate. Good.

Danu

I decided it's better if I don't. Plus, as a mod on a different site I can already do some of the things I would like to do as a mod anyways.

0celo7

like banning me

Danu

@DanielSank :D :D It's the power-hungry in us

LOTR: The Fellowship of the Ring - Galadriel - All shall love me and despair

►

user116211

@0celo7 building walls ... although I need to find a context for wall here.

Danu

9:07 PM

@AlfredCentauri :)

Slereah

And then via some wizard magic you can get $$^\rho f(\chi) = \sum_n \frac{f^{(n)}(a_0)}{n!} \eta^n$$

Which is probably the magic "it's better for analysis" theorem

0celo7

ok I have voted

I voted by sexiness

Slereah

Well I'm glad you voted for me

user116211

@0celo7 There is no Lumo.

Slereah

Me I always vote for the tallest guy

0celo7

9:10 PM

vote for trump

@MAFIA36790 I know :(

DanielSank

@Danu I like to think that arguing all sides of an issue really helps on understand that issue better.

It's hard to imagine that not being true :D

user116211

@0celo7 He is very busy with his blog lately.

user218912

his blog looks bad.

user218912

but the content is probably good.

Sir Cumference

I feel that awarding a badge for voting is a horrible idea

user116211

9:12 PM

@IceLord NOOO!!

0celo7

I GOT A BADGE

user116211

@IceLord yes.

Sir Cumference

It encourages newbies or lazy people to vote randomly just to get a silver badge

0celo7

WÖÖÖÖÖÖ

user116211

@0celo7 Constituent

DanielSank

9:13 PM

@MAFIA36790 o/

0celo7

what language is that?

o.o

DanielSank

@0celo7 Keyboard was set to Russian.

user116211

@DanielSank I thought you were speaking in new version of Klingon.

0celo7

why are you typing in Russian?

user116211

Anyways, \o

DanielSank

9:14 PM

@0celo7 I have a sore throat. I didn't want to spread it at work so I stayed home. I'm doing my daily Russian lesson.

user116211

A gigafine for Deutsche Bank is a plain robbery

Danu

Classic Lubos

DanielSank

Should I add a hall of shame, listing bad books, to my list of good technical books?

Slereah

I imagine Lubos as some kind of post-apocalyptic eastern european, in a trenchcoat and gasmask, eating cold beans out of a can sitting on his ammo box

4

DanielSank

LOL

user116211

9:17 PM

Many of his posts are serious anti-commies.

Slereah

Something like that

user116211

He doesn't like John Kerry too.

user116211

I mean not the author of my topology book ;P

0celo7

Is there something wrong with me if I agree with everything Lubos says

Slereah

Yes.

user116211

9:20 PM

@0celo7 He doesn't like Trump.

Slereah

It is time to dig your own grave

user116211

He doesn't like anything, if I say in brief.

Slereah

He likes string theory

Danu

@DanielSank Lol yeah

user116211

Well, that's THE One thing.

Slereah

9:21 PM

"Michael Oberguggenberger"

100% sure that's a fake name

Danu

@0celo7 Yes.

It means that you're Lubos Motl

DanielSank

@Danu Ok. So far that's going to be Kittel's book on solid state physics.

Total POS.

Slereah

What the hell is the algebra $E(\Omega)$

0celo7

@MAFIA36790 why not?

I don't think I do either

Danu

@DanielSank The only really good physics book I ever read was Carroll's GR book.

Slereah

9:22 PM

Those papers have way too many spaces

0celo7

not anymore

user116211

@0celo7 What? Didn't you vote for him, if I'm not mistaking?

Danu

I think Dirac's original QM book is also pretty good but I didn't read very far.

Slereah

Is it the distribution algebra?

fugg

DanielSank

@Danu Reif's stat mech book is very good.

Here are the books I like

Danu

9:23 PM

Griffiths' electrodynamics book has its charms :)

Slereah

What is the worst book, though

Danu

Ah, you have it on there.

@DanielSank small typo in the bit about Sakurai:

> does not life the degeneracy to first order.

(should be "lift")

Slereah

My worst book is "Spinors"

I bought it only to realize that it was just wikipedia articles printed together in book form

Danu

Oh yeah, hall of shame: Hartle's GR book.

DanielSank

@Danu This is why github is so awesome.

Danu

9:25 PM

2complicat4me

I'll make you explain it to me some time when I need it.

DanielSank

@Danu Just click the link.

You can see that someone already noticed the typo and informed me in a very nice way.

Danu

Okay, great :)

Slereah

Apparently Robinson published a book about his nonarchimedean fields

Maybe it is less shite than this paper

Let's obtain it legally

Danu

You know what's a really great book: Guillemin & Pollack's Differential Topology

Mukhanov's book on QFT in curved spacetimes is interesting and cuts the crap, getting you to interesting stuff fast (very intuitive)

Oh yeah, hall of shame: Ryder's QFT book.

Terrible

Slereah

Birrell and other guy on QFT in CST is also good

Less good : Wald on the topic

Danu

9:28 PM

Carroll was fucking excellent on it in just a single chapter

(not a lot of material covered obviously)

Also terrible: Misner, Thorne, Wheeler's GR book

Slereah

Well

MTW is like the bible

Poorly organized, but all your answers are in there

DanielSank

@Danu typo fixed.

Danu

k

Oh yeah

Zee - QFT in a Nutshell sucks

DanielSank

I'm only going to list books I've read :)

Danu

I know, I know

it was more like a trip down memory lane for my own enjoyment than actually aimed at you :P

DanielSank

9:31 PM

Now that we're on the topic of QFT though, I have a question for you, @ACuriousMind and anyone else.

Mikael Kuisma

Hi! Could someone remove community wiki flag from my answer. It seems that I accidentally checked that with my cellphone.

DanielSank

For as person like me who knows quantum mechanics pretty well, understands second quantization just fine, and has a reasonable level of mathematical maturity, what should I read to learn how to use QFT to solve problems?

Danu

@MikaelKuisma Flag your own post, and use a custom explanation.

Only moderators can do it.

DanielSank

I am not interested in the particulars of Lortentz invariance in QFT. I only care about quantum fields per se.

Danu

@DanielSank So what kind of problems?

ACuriousMind

9:32 PM

@DanielSank How to solve what problems?

Danu

Okay, so you don't want any high energy stuff

lol

Mikael Kuisma

Thanks danu

Danu

so none of the books we've read will help you

ACuriousMind

If you want to do CMT, it's going to be very different from HEP

Danu

But I've heard of some condensed matter field theory books

DanielSank

9:33 PM

@Danu Go on.

@ACuriousMind For example, a vibrating string.

Danu

So I heard of Fradkin - Field Theory of Condensed Matter Physics

@DanielSank So classical string theory (no joke :P)

DanielSank

@Danu No. A vibrating string that is isolated from decoherence.

Danu

But classical string theory is actually about solving the equations of motion of a real life string :P

Okay, it's relativistic... but still

Slereah

Guitar strings are relativistic

You just don't play fast enough to notice

Danu

Also the obvious Google search maybe, Daniel?

I honestly think the people here can't help you with anything that you're interested in much more than a random internet search will.

DanielSank

9:36 PM

Really?

Danu

Because nobody here knows much about non-relativistic QFT :D

DanielSank

Ah.

That's lame.

ACuriousMind

@DanielSank You want to take the classical field theory describing a vibrating string and quantize it?

DanielSank

Where all the non-relativistic QFT people at?

Danu

Welp, that's what I'd say about non-relativistic physics.

DanielSank

9:37 PM

@ACuriousMind That would be a baby step, yes. And to be honest I know how to do that much.

I basically want a book that starts somewhere around there.

Danu

Anyways, the google search seems to give a lot of potentially good stuff.

Honestly, I think it might be a great idea to post a question on main.

Slereah

Well the obvious field theory to quanticize is EM and it's already relativistic

DanielSank

Yes but obviously the reason I asked for recommendations is to narrow the list.

Danu

You know, asking specifically for CMT field theory

DanielSank

@Slereah That's a very complicated starting point.

Slereah

9:38 PM

But the obvious one

DanielSank

@Danu I don't understand how resource recommendation posts work.

Slereah

Also KG field is also relativistic

DanielSank

I probably should learn.

ACuriousMind

I think I agree with Danu that you're probably searching for a condensed matter QFT text then. I can't recommend any because I haven't even read a full book on relativistic QFT and that's much more my field :P

Danu

@DanielSank There isn't much to it. Just check some highly upvoted ones. It's pretty simple.

Slereah

9:38 PM

What non-relativistic field are you going to quantize

A temperature field?

DanielSank

What's a temperature field?

The temperature

o_O

it's a scalar field

@Slereah He already told us: For example. just a non-relativistic string

Slereah

9:39 PM

$T(x,y,z,t)$

Danu

You know, number at each point in space :P

Slereah

But a string isn't a field

ACuriousMind

@Slereah It is described by a classical field theory, though

Not every field theory is about those ephemeral fields "pervading space and time"

DanielSank

@ACuriousMind I'm glad you said that.

Danu

hehe

Slereah

9:41 PM

@ACuriousMind Yes they are you fraud

DanielSank

I have in mind actually voltage/current in a superconducting resonator.

Danu

World-sheet action 4 lyfe :P

Slereah

That's like saying a point particle is a 1D field theory

DanielSank

It's taking all my will to not set up a soap box right now.

@Slereah ::twitches::

Danu

It's so easy to trigger you about certain topics

DanielSank

9:42 PM

@Danu Yes, particularly topics involving mass scale undue confusion within my profession.

Slereah

I'm having trouble buying that book legally

Short of actually buying it legally

Mikael Kuisma

About non-relativistic qft. I just went through an interesting but not so novel loop. I am studying plasmons, very non relativistic. I realized that qft could be used to describe them. After few months, I realized that higgs mechanism is very much like plasmons. Then I went back to Higgs original paper, who referred to work of Anderson from plasmons. So the circle was complete.

Slereah

It is on google books but a bit incomplete

DanielSank

@MikaelKuisma Yes! Take that, Lorentz-invariance fanboyz!

ACuriousMind

@Slereah If you mean the spacetime dimension, then yes, a particle is a 1D field theory and a string is a 2D field theory. What's the problem?

Danu

9:44 PM

@MikaelKuisma Yeah, Higgs mechanism came from condensed matter physics :)

Slereah

It is immoral to make such claims

apparently there are non-archimedean groups

Let's see what they are

Mikael Kuisma

It was sort of nice to do this discovery fee other way my self. On the other hand, very disappointing since this was discovered more than 50 years ago.

Fee = the

Danu

@Mikael Maybe you can give Daniel some recommendations on CMT field theory.

DanielSank

It's not so much that I care about condensed matter.

Mikael Kuisma

Well, I guess the ground breaking is the GW paler by Hedin.

DanielSank

9:47 PM

I just would like to learn the basics of QFT without having to worry about learning Lorentz-invariance at the same time.

Mikael Kuisma

Paper

Or perhaps Fetter-Walecka

g.co/kgs/UfCIpL

But these are very condensed matter of course.

Erik Jörgenfelt

On the other side of the board, are there good introductory QFT texts adapted to those familiar with GR?

DanielSank

woof, definitely getting into the hard parts of Russian now.

@MikaelKuisma Thanks.

Slereah

How exactly do you go from GR to QFT

Erik Jörgenfelt

@Slereah If you mean why I know GR but not QFT, it's partly because I did and undergrad maths in differential geometry, and then my undergrad physics in GR, as well as a project course in GR, but haven't had time to go though the normal course path to get to QFT. Until soon.

Slereah

9:57 PM

I mean more how do you go on one to the other

They don't have that much in common

Mikael Kuisma

Isn't that the fundamental problem of modern physics, that one does not go from GR to QFT

:)

If you figure that out, you will get a nobel price

Erik Jörgenfelt

I'll take your word for that :) I just figured that I know QFT can be applied on *fixed) curved background metrics. So there should be a natural formulation in the language of GR, and it would probably be less confusing than working in formalism that depends explicitly on a flat metric. Perhaps I'm overthinking things though

Slereah

well you can do algebraic QFT

Danu

@ErikJörgenfelt It doesn't really influence each other too much...

Slereah

Which is a mapping from light cones to C* algebras

Danu

10:01 PM

Screw algebraic QFT

@ErikJörgenfelt There are some QFT in curved spacetime books. Mukhanov's is very intuitive and I think very good.

Birrell & Davies is much harder but more complete.

There are some major differences between QFT in curved spacetimes and QFT in Minkowski though.

The main one being that the notion of a "particle" is not easily unambiguously defined in curved spacetimes

Slereah

Well it's not too hard

But it is frame dependant

Mikael Kuisma

Hah, particle is never unambiguously defined, unless one is talking about some asymptotic scattering state.

Slereah

or just free theories

or some interacting theories

Erik Jörgenfelt

Thank you, guys. I'll have a look

Danu

@MikaelKuisma Yeah---but even that runs into trouble in curved spacetimes.

Hence the Hawking & Unruh effects.

Mikael Kuisma

10:06 PM

Hmm... in the (yet to come) gr-qft this might then be interpreted as some graviton-fermion quasiparticle:)

I really know nothing about gr, but I am very interested in "what is a particle" in general

Slereah

not really

The trick is that there are really no particles in QFT

It's just a convenient fiction

Mikael Kuisma

I agree completely

Danu

@MikaelKuisma wat?

DanielSank

@MikaelKuisma Nobel price: Misspelling of "noble price", which is the minimum amount of money one must receive when taking a bribe such that their honor remains intact (presumably because the sum of money is so high that no sane person, regardless of ethics and honor, would be expected to reject it).

Mikael Kuisma

To what did the wat refer to?

Danu

10:14 PM

@DanielSank lol

Mikael Kuisma

But particles, I find that for just intuitions and interpretations sake, it is nice to basis transform into propagators which poles make sense. Like Higgs or plasmons for instance.

Erik Jörgenfelt

@Danu Birrell&Davies looks very good at first glance. Thank you :)

Danu

From facebook:

> beautiness

WHYYYY

Slereah

10:34 PM

Birrell and Davies is pretty good

Probably not the best place to learn QFT, though

For QFT I'd advise more Schwartz

I have legally acquired that book on asymptotic numbers

Let's hope it will illuminate

Slereah

10:58 PM

really it sounds silly but I think refering to filter sets as "big" is more pedagogical than just going drily about ultrafilters

Erik Jörgenfelt

OK @Slereah, perhaps I would benefit from both. I'll have a look

ACuriousMind

@Slereah I don't think it is any more silly than to call the elements of a topology open ;)

Slereah

Well it's not necessarily very true on some sets

Since it's possible for the set of even numbers to be big and the set of odd numbers to be not big

The Bee Bit My Bottom!

►

Physics Meta

0

Q: Realist, optimist, pessimist, rookie... Which word do you think best discribes our nominees for 2016 moderator?

I have seen our nominees for 2016 moderators and these are some words I would use to describe some of them. In your opinion which single word best describes each of them? ACuriousMind rob Alfred Centauri from The Last Star Fighter tpg2114 Jim

Slereah

11:19 PM

Oh no

Zorn's lemma

0celo7

@ACuriousMind What's wrong with that?

@Slereah Is false.

Slereah

Obliv

isn't zorn's lemma the one that proves well-ordering in sets

0celo7

it's equivalent to it

Slereah

one of them, yes

can you bad order a set

what is the worst order

Obliv

11:32 PM

disordered

Slereah

11:42 PM

Hyperreals are a bit tedious to read because they involve a lot of first order logic

With the Los transfert theorem and all

0celo7

so

Obliv

man I was watching a feynman interview because I was bored and he said something along the lines of "history is fundamentally irrelevant [to physics]". If he were alive I'd have to have a talk with him..

0celo7

is a countable union of countable sets countable?

I know it is but I need someone to confirm

Obliv

no

what the hell is a countable union anyway

0celo7

no?

Obliv

11:49 PM

yes.

0celo7