@ACuriousMind It has the advantage of not being directed at any particular user or post.

@dmckee Well, if it were, it would be so offensive that I'd have immediately flagged that post

@ACuriousMind if you're doing something else or just want me to figure it out, please say so...

@0celo7 I'm not really sure what still confuses you, so I'd prefer you figure that out yourself

@ACuriousMind I haven't the slightest clue why your thing is left invariant...

You just check it, there's no trick involved, it follows from the $X_i$ being left-invariant.

I don't know how to check it

Well then you don't know what left-invariant means!

it just means the pullback doesn't change it

but I don't know how to take the pullback of the form you defined

maybe that's the issue

well, I don't, so that's at least part of the issue

@0celo7 Yeah. So carefully write down what the pullback does to that thing and check it doesn't change.

@ACuriousMind I don't know how to do that.

Well, then go back and examine the notions of pullback and left-invariance until you get it, I don't think there's another way.

What's all this Fraktur

It looks like I'm reading a Gestapo document

@ACuriousMind I HAVE!

@Slereah lol

My god what is even AQFT

I do not understand a thing

@0celo7 Then I don't know how to help you, I just feel that just showing it to you doesn't do any good.

@ACuriousMind :(

I have no clue what to do then

@ACuriousMind do I need to determine $\omega_g(dL_xv)$?

but what space is $v$ in...

$T_{x^{-1}g}G$?

do I have to use the curve definition of the pullback?

or is that the pushforward that has a curve definition

@ACuriousMind what if instead I calculate $\omega_{xg}(dL_xv)$

then $dL_xv=dL_xdL_gX(e)=X(xg)$

I'm not going to say yes or no to any of that - if you think something is worth a try, try it!

dude I'm obviously confused by the definitions

I don't know why you refuse to help when I'm confsued by the very things I'm supposed to be working with

so by definition $\omega_{xg}(X(xg))=\omega_e(X(e))$

and $\omega_{xg}(dL_xv)=(L_x^*\omega_{xg})(v)$

@0celo7 Because that shows me that you went too fast - you didn't actually grasp those definitions, and now you are having trouble unpacking them. You rely on always being able to ask someone who knows - and while that is sometimes necessary, it seems to me you are outsourcing a critical part of understanding.

@ACuriousMind I do grasp the definitions

I don't grasp how to apply them to your thing

so it's your definition that is confusing me

@ACuriousMind Particularly, I don't understand how do to this stuff pointwise

Everything that's needed to understand it has been said. You just need to piece it together.

like I know that $$(F^*\omega)_p(v)=\omega_{F(p)}(dF(v))$$

but I don't see how to apply that to the form you defined!

Uh, why not? You literally just plug it in

I KNOW

I don't know what to do after that

$$(L^*_x\omega)_g(v)=\omega_{xg}(dL_x(v))=\omega_{xg}(dL_xdL_gX(e))=\omega_{xg}(‌​X(xg))=\omega_e(X(e))=\omega_g(v)$$

@ACuriousMind Is that correct or not?

here $\omega_e\in\Lambda^n(\mathfrak{g}^*)$

@0celo7 Yes, that's correct. What was so difficult about it?

@ACuriousMind EVERYTHING

I don't know why you made such a big deal out of it :/

Probably true. But could I have really helped with that?

@ACuriousMind Yes.

Well, maybe I'm bad at this, but I don't see how (without just typing it out)

By typing it out...

But I didn't want to type it out because this is precisely the sort of argument that is supposed to be "obvious"

And it doesn't become obvious to anyone if they don't wrestle with it often enough.

Does AQFT really need category theory

Isn't category theory for totally abstract math objects

@Slereah Nothing needs category theory, but as soon as you're dealing with sheaf-type maps (such as I think the local assignment of an algebra of observables) it's really the frameowrk that you should be using to talk about stuff.

Looking up "abstract nonsense" on wikipedia

"The term is believed to have been coined by the mathematician Norman Steenrod"

:D

Funnily enough I was talking to a guy earlier about category theory! He used this example as to why it is useful (that went something like) "you can define an (action or maybe it was morphism I can't remember) on a set as the identity will not change it" but then what if the set is a group or a graph then how does the definition of the (action) preserve the group structure -- it doesn't. While if you use category theory you can define it in terms of some automorphism (or something) and

it preserves the structure of the object

I actually don't remember that much of the conversation

just thought I'd share that

:)

@Slereah what's in vault 95

I cleared it and didn't find anything special

was a bitch to clear, very powerful enemies

Vaut 95 is... Gunner vault I think?

Bunch of assholes with lots of guns

yeah

killed them all

went in with my power armor

I like how once in a while, you find a supermutant with the orders on him

And you think it's gonna be a quest starter or something

but it is just written "Destroy everything" on a piece of paper

oh so I was walking around with Belethor

and there was a battle

with Brohood guys

They are uncomplicated

and they just started shooting at him

@Slereah I have a few of those

@ACuriousMind Not playing F4?

@0celo7 Not all of us have your ridiculously fast connection :/

you can just buy the physical game, you know

@Slereah or sneakily go to the UH library and download it there

is ~ not the console button in this game?

Depends on the keyboard

Not in France anyway

It's ^ usually for me

I really don't want to learn AQFT but all weird GR things in QFT are done with it

Either that or path integrals or hadamard forms

Well you can do it with canonical QFT but it gets a bit ill defined once weird things happen

@Slereah huh?

Well QFT on spacetimes with CTCs or not time orientable are usually done with some variation of AQFT

or path integrals

@ACuriousMind protip: desk fans are wonderful things

Huh? It's November, why would I need a fan?

Aaaah

Three suicide bombers

AT ONCE

Uh...in the game, I hope?

yes

I know I'm in Paris but still

Bad timing, by the way, Bethedas

A game with suicide bomber this week?

@ACuriousMind physics.stackexchange.com/review/low-quality-posts/106544

I disagree with your statement there: The guy does explain why it's a good resource (by discussing the difficulty level).

@Danu It just says that it's the "right" difficulty level. That's not "discussing" the difficulty level.

Furthermore, I don't understand your motivation in flagging this: There seems to be nobody who can benefit from that.

@ACuriousMind Fine, if you insist on being pedantic about it I'll edit it myself to make it conform. I think it's important that this book is mentioned in a post on reading recommendations on QM. I don't understand why you think strictly conforming to the official policies (which this only violates in a minor way) is more important here than providing valuable content, in this case.

@Danu To me, such a recommendation is just meaningless, subjective noise. It's not "valuable content", if I read this, I have no idea why I should choose that book over other except that a random internet stranger said so and others agreed with him. There's no objective information to be gotten from that.

@ACuriousMind There is, IMO.

For a recommendation answer to be useful, it has to offer some information, something of substance

I think this is sufficient.

Okay, let's turn this around: What do you think this post adds?

Because I genuinely don't see it.

Whatever, let's agree to disagree.

Next time you flag a highly upvoted resource recommendation, please let me know in chat.

Whenever possible, I'll improve the answer to make it fit your standards.

I think it's important to preserve these things: I've personally hugely benefited from answers like this and do not want to make it impossible for others to do so too.

@ACuriousMind For one, even the fact that Griffiths' book is mentioned is valuable to me.

Because a good res. rec. thread should include the standard texts, and this is one of them.

You may not give a damn, but I do care about knowing what the standard books on many topics are.

I suggest you keep this kind of value in mind.

"As far as axioms are concerned, notice e.g. that, on many spacetimes { the spacelike cylinder being one example { there are no spacelike related pairs of points and the Spacelike Commutativity Axiom would, in consequence, be empty of content"

Oh no

My causality

"For a spacetime (M;g) with compactly generated Cauchy horizon, it is now known quite generally [9] that, with the mild technical assumption that the algebra admits a state ! in which the non-exponentiated smeared two-point function exists and is distributional, then there is no algebra B(M;g) which satisfies F-locality."

I am alarmed

The fact that you're trying to have the top answer on 64k views question deleted is something that should make someone think twice (and yes, I do realize many views does not imply quality content, but it does to some extent measure the importance of the question to the average internet person)

@Danu Flagging an upvoted post does not get it deleted, even if the reviewers agree, see this, so you're way overreacting here.

@ACuriousMind ah

that changes a lot.

It gets the reviewers and mods to take a look at it, with the hopeful outcome that it gets improved.

@ACuriousMind Okay, fair enough. I repeat my statement about linking me in chat, then.

I'll try to improve the answers :)

@Danu Fair enough, since I mostly can't improve them, but especially the top-voted answers on those questions should be examples for how answers to res.rec. questions should look.

@ACuriousMind To me, the top answer mentioning the standard text is already pretty decent :P

By the way, I think that's a sneaky little fact, that non-mods cannot delete upvoted answers.

@ACuriousMind also duct tape

And typewriters and globes

@Danu Well, but it prohibits exactly what you were worried about - a minority of users deleting content that more people found useful than not.

Surgical trays too!

@ACuriousMind Yup.

Not "sneaky" in a bad way :P

@0celo7 Still ~4h till it's finished, don't try to excite me too much ;P

@ACuriousMind Ok, will try not to

@Slereah "follow freedom's trail"?

wtf?

I go to the place and there's a robot

he told me I need to follow some markers

can't find the markers -.-

Look on the ground

There's a plaque

And a red line

Trying.

@Slereah where is the next one after the graveyard.

The trail just stops

Look a bit ahead

wtf

nothing there

welp

Enough side quests for now

Back on the main quest

Hm, who to bring along

Let's go with Nick

I like him

Why don't we just nuke MIT and kill the Institute?

Oh god

I'm gonna have to fight a courser

I'll go get my nukes

Welp

Got my nukes, my rockets and my power armor

Let's roll