The h Bar

Danu

15:00

This is a really nice setup for posting a good, extensive answer that outlines how the integral emerges as the limit of Riemann sums

ACuriousMind

Well, then write it!

Danu

I'm tired and feeling depressed

0celo7

@Danu depressed?

Has anyone seen this definition before?

Danu

@0celo7 Probably a nice exercise to prove equivalence (you can fix the dimension to be 4, or even 3, for simplicity)

0celo7

@Danu It actually is an exercise in the book :P

I'm just wondering why one would define the Lorentz group like that.

Slereah

15:16

Odd definition

Why two -1?

0celo7

I don't know

ACuriousMind

I bet it is related to the Lorentz group being the conformal group in two dimensions lower

0celo7

And the proof of equivalence is not easy

Mb I need to go to the Lie algebra and show the exponentiations are the same

@ACuriousMind hmm, why do you think that

ACuriousMind

It's a hunch

0celo7

I bet you did the proof already

and won't tell me

Danu

15:19

@0celo7 Lorentz group is not even connected, is it?

0celo7

@Danu no, and that would only show their id-connected parts are equal

you are right there

ACuriousMind

$I_{n-1}$ would be the metric of signature $(n-1,0)$, and the Lorentz group of $(n,1)$ is indeed the conformal group of that (considered on the conformal conpactification). It just looks as if that could have something to do with it.

0celo7

I wonder if you can manipulate $A\eta A^t=\eta$ into $A^t\Sigma A=\Sigma$ by some clever trick

@ACuriousMind oh ok

I know know the thing about the conformal group from BBS

Danu

@ACuriousMind The "conformal compactification" is the (Alexandroff) one-point compactification?

ACuriousMind

@Danu No, the conformal compactification of $\mathbb{R}^{p,q}$ is the projective space of $\mathbb{R}^{p+1,q+1}$.

0celo7

15:23

damn projective spaces

Danu

Okay---why?

ACuriousMind

that's not $S^{p+q}$ (which would be the one-point compactification) in general, I think

Oh, sorry, you need to take the subspace of the projective space that's spanned by null vectors.

0celo7

hmm, I think $\eta$ and $\Sigma$ have the same eigenvalues

They might be similar.

ACuriousMind

Not sure why exactly, except that this gives a nice way to see that the conformal algebra is the Lorentz algebra from two dimensions higher

Danu

@ACuriousMind And this is supposed to be the same thing as in Penrose diagrams?

ACuriousMind

15:26

@Danu I have not the slightest idea about Penrose diagrams

I just know this is what we called "conformal compactification" in my CFT course

Danu

@ACuriousMind The way I saw is explicit commutators (and yes, that sucked)

^that's what we did in my CFT course

0celo7

@Danu that's how they do it in BBS

ACuriousMind

@Danu Ew

0celo7

@Danu I haven't heard projective spaces used in connection with Penrose diagrams

Danu

@0celo7 But those things are certainly conformal compactifications

0celo7

15:29

What the heck is a conformal compactification in the sense ACM is using

Danu

That, I don't know. But I feel the Penrose diagrams certainly deserve the name :P

0celo7

@Danu well yeah, you find a conformally related spacetime where your original spacetime is a compact submanifold

something like that

but what is ACM talking about

ACuriousMind

I'm talking about the embedding $\mathbb{R}^{p,q}\to I^{p,q}, (x_1,\dots,x_d)\mapsto [\frac{1-\lvert\lvert x\rvert\rvert^2}{2}: x_1 : \dots : x_d : \frac{1+\lvert\lvert x\rvert\rvert^2}{2}]$ into $I^{p,q} := \{[v]\in P(\mathbb{R}^{p+1,q+1})\mid \lvert\lvert v \rvert\rvert^2 = 0\}$, apparently (just looked into my notes).

Danu

Right

I'm feeling a connection to "conformal" through the connection between that $1-\lvert x \rvert^2$ factor and the hyperbolic disk (and hence conformal transformations)

maybe

0celo7

15:53

@Danu Ok, if $\Sigma$ and $\eta$ are similar and the similarity transformation is an orthogonal matrix, the proof is complete. I'll leave you to check that...

ACuriousMind

@0celo7 You can check that yourself. Train your linear algebra.

0celo7

@ACuriousMind I did enough of this crap last semester

ACuriousMind

Obviously not, if you don't see the similarity transformation immediately :P

0celo7

Ok so there is an orthogonal similarity transformation?

ACuriousMind

If you think that was meant as a hint, you missed the point entirely

0celo7

16:03

Huh?

How the heck do you find a similarity transformation anyway :P

TheGhostOfPerdition

Hey, I have a small doubt, There was a question given in a book which asked to calculate the probability of finding an electron inside the nucleus, i found that it was somewhere around 10^-15..... but what does it really mean to find an electron inside the nucleus? does the answer make any sense?

@ACuriousMind could u please answer my question?

0celo7

16:27

@BernardMeurer Regarding being a Jehova's witness about my proof, I have not actually made Rebecca read it.

So I don't pester everyone about it.

ACuriousMind

-1

Q: Need help with these questions

I am doing these question as a practice but do not have their solutions, so after solving them i do not know if the answers are correct. Can anyone solve them and post a brief description. 1. For the production of rainbow light is; (a) reflected, (b) refracted, (c) ...

Seriously?

0celo7

Lol

ACuriousMind

17:10

9

Q: Do the LIGO observations constitute proof of a black hole merger, and what happened to the black holes?

Moderator linked another question of mine Does LIGO GW detection methodologically constitute discovery of two specific black holes (as astronomical objects)? as a duplicate of this question Information says that the gravitational waves, recently detected by LIGO, correspond (according to Einst...

black-holes experimental-physics history gravitational-waves ligo

And wtf is going on in this question?

OP obviously does not understand the scientific method and keeps adding strangely worded requests for "references" other than the LIGO publications itself

Hari Prasad

@ACuriousMind What is the best book to start learning QFT?(as a begineer)

ACuriousMind

No idea, from what I hear they're all kinda bad

Hari Prasad

@ACuriousMind ok. But just to make a fair understanding of QFT?

ACuriousMind

I don't know, I haven't read any of them (except for parts of Weinberg)

Hari Prasad

@ACuriousMind ok thanks

@ACuriousMind Another question. How well does Noether's theorem hold to be true. is there any place where it gets inconsistent?

ACuriousMind

17:26

I don't understand the question. It's a theorem. How could it "get inconsistent"?

Hari Prasad

@ACuriousMind BUT it does correspond to conservation laws.

ACuriousMind

That's the theorem. Every continuous symmetry has a corresponding conservation law. What's the question about that?

Hari Prasad

@ACuriousMind i'am sorry its a maths problem not related to physics. Again sorry!

ACuriousMind

I have no idea what you are talking about

Hari Prasad

@ACuriousMind I found an excerpt from : Hodge Theory, Complex Geometry, and Representation Theory by Mark Green, Phillip Griffiths, Matt Kerr

ACuriousMind

17:36

And what am I to make of that statement?

You found an excerpt. How is it relevant to Noether's theorem or the question you're trying to ask about it?

(Posting the excerpt instead of just telling me you found it would be a first step)

Hari Prasad

@ACuriousMind I read that,............family of surfaces for which noether's theorem fails......

ACuriousMind

I am pretty sure that means one of the abstract algebra theorems of Noether, not the one physicists call Noether's theorem.

Hari Prasad

yes exactly "Noether-Lefschetz theorem for surfaces". its not in physics. i said you before. sorry

Danu

Finally starting in my book on Riemann surfaces :3

Bernard Meurer

@ACuriousMind Do you mind if I ask you some probably real dumb questions in the next couple of hours?

Reading Shankar and I get lost on some stuff

ACuriousMind

17:45

Ask away

dmckee

@HariPrasad The core issue is what does "as a beginner" mean to you? Do you have a solid handle on quantum mechanics in the Dirac and Heisenburg formulations as well as a solid preparation in terms of linear algebra, group theory, multi-dimensional calculus and the calculus of variations (as well as all the basic prerequisite skills for those subjects, of course)?

Hari Prasad

@dmckee you mean to start learning QFT?

dmckee

Yes.

Hari Prasad

@dmckee "Maybe a little bit more". I do know about Field Equations and their Solutions, The Canonical Commutation Relation, Creation and Annihilation Operators a few things about Gauge Theory and Interactions and also what you said

I'am a newbie to QFT

But Nothing in very high detail

Danu

Why don't you just pick up a book like, say, Schwarz' one, and see how it goes?

Hari Prasad

17:57

@Danu yup that's what i'am going to do. Thanks

dmckee

@HariPrasad What's with all the bold? It makes your writing harder, not easier to read.

Basic rule: emphasis should be rare, and you use italics for that purpose. Bold essentially never belongs prose.

Hari Prasad

@dmckee sorry. Can i ask you something?

dmckee

Putting emphasis in everything defeats the purpose, because then "every[thing] is special".

You can ask. I might even answer.

Hari Prasad

@dmckee ok. What does the INSPIRE links in your profile page corresponds to?Are you co-authour of all those papers?

dmckee

Yes, those are papers on which I am credited as an author.

0celo7

18:08

@BernardMeurer wow why don't you ask me

dmckee

Mind you, some of them aren't "papers" as such, but proposals and policy statements and stuff. InSpire vacuums up anything on arXiv and those kinds of un-peer-reviewed materials sometime end up there.

Hari Prasad

@dmckee Ok. So you are an Experimental physicist?

dmckee

These days I'm at a teaching university so my experimental activities are very much reduced, but that's my training.

I'm basically just trying to get the undergrads (the only students we have here) some time in the lab doing something less contrived than a typical set-piece lab exercise.

Danu

Btw @yuggib Connes did some pretty weird stuff---the output is a classical field theory on a manifold with quantized volume.

Bernard Meurer

@0celo7 I thought you were in class, that's why

Hari Prasad

18:12

@dmckee that's really great sir.

0celo7

@BernardMeurer I am

vzn

@dmckee do you ever succeed? it would be way cool if any were interested in nonlocality, or could be persuaded to be :)

dmckee

We haven't the kit be be interested in things as esoteric as that. I've got some students working on using a digital camera as a RICH detector and another one working on printing diffraction gratings to order.

Stuff that can be done on a few hundred dollars a year budget.

Slereah

18:33

@dmckee snore

Do some theory, it's like $0 a year budget :p

Danu

@dmckee I've posted this before

video.ias.edu/wam/2014/0516-TadashiTokieda

But that shit is awesome. And cheap. I'm really interested in the question he poses about the half-filled cylinders

dmckee

Hmmm ... I need to find the time to really watch that. Thanks.

Danu

@dmckee I have another awesome related thing, let's see if I can find it

arxiv.org/abs/1506.03097

hubot

Hi! How to transform Cartesian coordinates system to generic coordinates system?

Danu

Google "coordinate transformation"

dmckee

18:42

@hubot You bat your eyelashes and say "Hello, Jacobian! Is that a partial derivative in your pocket or are you just happy to see me?"

4

hubot

I love integrals and partial derivatives. My friends hate when I says to their about integration calculus.

dmckee

I was, in any case, being somewhat facetious. You don't need Jacobians until you start transforming integrals or differential equations between coordinate systems. I really wrote it offer another search term: "Jacobian".

hubot

Jacobian is a anything related to functions of several variables

vzn

18:58

@dmckee interesting. actually think lately that low-budget nonlocality experiments are possible but nobodys fleshed it out yet. any students interested in QM?

in theory salon, 1 min ago, by vzn

The CIA and Jeff Bezos Bet on Quantum Computing / MIT Tech review

0celo7

@hubot Look into differential forms if you want to see where Jacobians come from.

vzn

@dmckee whats a RICH detector?

ACuriousMind

@0celo7 wat

The natural appearance of the Jacobian is as the linearization of the function, just like the appearance of the usual 1D derivative as the slope of the function.

Danu

Look into Jacobians if you want to see how forms transform :D

0celo7

@ACuriousMind huh?

Jacobian determinants in integrals

@Danu or that :P

ACuriousMind

19:08

@0celo7 Far better to explain those simply by the usual conception of the determinant as the factor by which a linear transformation changes the volume of the unit cube. You can show that without introducing the full machinery of forms, and it is the same geometric picture that the forms represent.

0celo7

@ACuriousMind I've always found forms more intuitive

But maybe that's just me

And Zee does forms without machinery and it's beautiful

hubot

Do you know any method to fast solve Feynman and Landau exercises?

ACuriousMind

Hard thinking.

(That's literally and entirely what Feynman's professed approach to problems was)

hubot

I live in noise and stress. How to concrentrate on this exercise in these conditions?

0celo7

Live on the top of a mountain

hubot

19:15

0celo7: So, what do you mean?

ACuriousMind

Fun question: Does deleting a bounty-winning answer from review remove the bounty points from the answerer?

Bernard Meurer

Is there a bounty on that question?

0celo7

@hubot remove yourself from the noise

ACuriousMind

Because I just came across a bounty-winning answer at -5 in the review queue, and it really is just a personal, completely non-mainstream theory.

Bernard Meurer

@ACuriousMind Link?

0celo7

19:17

Link?

ACuriousMind

-5

A: Where does gravity get its energy from?

There is no Gravity, and there is no Mass. It's all just photons. What we experience as Gravity is photons with frequency $<1 Hz$. This means wavelengths from $300 000 000 m$ to approx. $\lambda_{max} \approx 6\pi^2 c^2$ or $2.4x10^{19} m$ -This is approx 1/40 of the size of our Galaxy. These p...

0celo7

Proof?

Oh that guy

ACuriousMind

I mean, it is an attempt to answer the question, but I cannot in good conscience click "Looks OK" for that.

Bernard Meurer

I think that's the guy that gave me shit the other say for saying Perelman had the persona of a mad scientist

hubot

How much time average do you think about Feynman problems?

0celo7

19:18

Years.

Bernard Meurer

@hubot what?

ACuriousMind

I guess I will skip it and wash my hands of the responsibility.

hubot

I think about Feynman problems since year.

In turn I think over Feynman exercises in Atoms in motion about month.

Is it a long?

ACuriousMind

I don't think I've ever thought about any "Feynman exercise", unless some of my courses used them as homework.

Bernard Meurer

@0celo7 How I attempt to solve my exercises: en.wikipedia.org/wiki/Bogosort

@ACuriousMind $\sum_{i=1}^{n} a_{i}|i\rangle = |0\rangle$

0celo7

19:24

I'm in class dude.

ACuriousMind

@BernardMeurer That's not a question.

Bernard Meurer

I don't quite get what's happening

Is he just saying that there's no $|i\rangle = |0\rangle$?

ACuriousMind

The $\lvert 0 \rangle$ is the zero vector in this horrible notation, right?

Bernard Meurer

Yep

Danu

@BernardMeurer Disgusting kets

Bernard Meurer

19:30

@Danu I've already learned to just use $0$ as opposed to $|0\rangle$

hubot

I have to go

Bernard Meurer

because $|0\rangle$ is the ground state

ACuriousMind

@BernardMeurer He's saying that if $\lvert j \rangle = 0$ for some $j$, then $\sum_i a_i \lvert i \rangle = \sum_{i\neq j} a_i \lvert i \rangle + 0 = 0$, so $\sum_{i\neq j} a_i\lvert i\rangle = 0$, so you can just eliminate any potenital zeros among the $\lvert i \rangle$ without impacting the form of the equation.

ACuriousMind

8

Q: Where to publish research if I do not want a peer review process?

I have a few papers, one of which is on a topic that, after thorough checking, has not been researched from this particular angle before. My question is where can I publish this without going through peer reviewed academic journals? I only have my undergrad, and am looking to publish the work t...

publications peer-review

Very suspicious question :D

Bernard Meurer

@ACuriousMind Gotcha

user54412

19:36

@ACuriousMind why does no one there seem to address the underlying issue?

user54412

the question is clearly based on the confusion that academic publishing = peer review, while rest-of-the-world publishing = binding into a book

ACuriousMind

Now this is clever. Deleting the question to take it out of the close review queue, letting the close vote age away, undeleting it a month later.

Danu

@ChrisWhite Wait, what?

user54412

@ACuriousMind Can you re-vote to close?

ACuriousMind

@ChrisWhite I could, if I had close votes left.

user54412

19:39

@Danu what what?

ACuriousMind

@ChrisWhite I'm not really following you either, actually. The question is seeking to publish (in an academically relevant way) without time delay, and just says "no peer review process" because it perceives that as the primary hindrance

Danu

@ChrisWhite I think you're confused about the OP's confusion ;)

user54412

@ACuriousMind but that's not publishing!

Danu

Actually, the OP is not really confused, but just mistaken about a non-peer-reviewed manuscript making an impact.

user54412

it doesn't matter if a book publisher binds and distributes my manuscript around the world -- I can't go and say I'm "published" in academia without peer review

John Duffield

19:44

@0celo7 : I'll explain it in an answer if you like.

Danu

@ChrisWhite There are non-peer-review journals, I'm sure.

ACuriousMind

@ChrisWhite Yeah, the answers are a bit soft on schooling the OP that peer review is an integral part of academia.

user54412

@Danu which don't count as being academically published :p

user54412

if this was the 1920s and science was guided by listening to famous people, then sure

user54412

but we've moved on (or at least in my world we have)

ACuriousMind

19:46

But the answers on Academia are generally a bit soft on setting the askers straight :P

user54412

@ACuriousMind unless there's an issue of self-plagiarism, in which case they use all the fire and brimstone

user54412

@ACuriousMind So I'm wondering if that situation should be flagged. As in, is The Void a sockpuppet feeding rep into that account? Or just someone else whose thought processes are completely incomprehensible?

hwlau

@Danu Non peer reviewed is not different from putting it on arXiv

user54412

@dmckee ^^

dmckee

@ChrisWhite This. Besides which I loathe the term "self plagiarism" because it simply isn't plagiarism. Academic dishonesty, sure, but never plagiarism: it can't be when it is your own work.

ACuriousMind

19:50

@ChrisWhite Pretty sure it's the latter

But you're right, one could flag that because it simply looks suspicious

dmckee

@ChrisWhite Well, we can't comment on things like that. But thanks for bringing it up.

Danu

@dmckee Not if your uni defines in to include self-plagiarism :P

dmckee

@Danu That just proves that the university is a pig-headed fool of an institution. The word means something, and you can't change that meaning willy-nilly.

Danu

@dmckee My uni certainly was :)

0celo7

20:07

@ACuriousMind yup

It's not disgusting.

vzn

@BernardMeurer youre interested in perelman? read a book (bio) on him a few mos ago. quite a character. to call him a "mad scientist" is in quite a few ways an understatement :|

user54412

@0celo7 marking every vector indiscriminately with a ket is akin to marking every vector indiscriminately with an abstract index -- it is indicative of the author fundamentally not understanding the structure of the mathematical objects they're working with

Danu

What I didn't know until semi-recently is that he also proved really "out of reach" theorems in Riem. geom. before his famous work on the geometrization theorem

Bernard Meurer

@vzn All I meant was he had the persona of the mad scientist. He's not mad. I don't think he's mad. I'm not saying he's mad. My point is, he's a recluse he has a peculiar look and he doesn't give interviews, it all builds a character

Danu

I think he's pretty mad

(not necessarily as in "mad scientist", just mad)

Not quite as mad as Grothendieck, probably.

Bernard Meurer

20:14

That's because Grothendieck was a bloody wizard

John Duffield

I say chaps, anyone for physics? How about somebody pick one of the problems in physics, and we talk about it.

Bernard Meurer

@JohnDuffield Tell me about the Kuiper cliff

Danu

@JohnDuffield Tell me about the low-energy limit of QCD and what's behind flux tubes

(not serious)

Bernard Meurer

Dibs on Abraham–Minkowski controversy!

0celo7

@ChrisWhite huh?

ACuriousMind

20:26

Fun fact, 309 of 866 messages containing "huh" in the h hbar come from @0celo7

Bernard Meurer

0celo7

@ACuriousMind Huh.

Proof?

John Duffield

@BernardMeurer : I can't tell you anything about the Kuiper Cliff. But I rather thought the Abrahams-Minkowski controversy was settled. See this physicsworld report entitled "Both answers correct in century-old optics dilemma".

ACuriousMind

It must be hard to exist in such a state of continual puzzlement

Bernard Meurer

@ACuriousMind Can you get the word @0celo7 has said the most so far?

ACuriousMind

20:27

No idea how to do that

Bernard Meurer

Write a python script, it's the solution to everything

@JohnDuffield I just picked from that list, let me pick another one

ACuriousMind

@BernardMeurer I'd have to figure out if the chat search function provides an API, that's not worth it

0celo7

@ACuriousMind what?

John Duffield

@BernardMeurer : besides, IMHO what's important is that energy and momentum are two aspects of energy-momentum, and mass is another. The slowed-down photon exhibits an "effective" mass, and there's a sliding scale between the massless photon propagating at c and the photon in the box which increases the mass of the system.

0celo7

@ChrisWhite what are you trying to say here

I don't understand

the smooth functions are a vector space, Shankar writes smooth functions as $|f\rangle$

Bernard Meurer

20:30

@JohnDuffield Are you talking about that light slowing down thing that always ends in fire, death and disgrace?

0celo7

I don't see what the issue is

@JohnDuffield ok, please

Danu

@ACuriousMind Why is that not surprising?

Bernard Meurer

Okay, I pick Yang–Mills theory then

0celo7

@Danu what?

I'm so confused

What are people talking about

ACuriousMind

@Danu It's not surprsing, it's just a fun fact :)

Danu

20:31

@0celo7 Say the magic word

John Duffield

@BernardMeurer : Fire death and disgrace? Er, no.

0celo7

@Danu huh?

Danu

:D

0celo7

I don't get it

Danu

You did perfectly

0celo7

20:32

huh?

Bernard Meurer

@JohnDuffield Every time you come up with that idea someone ends up having a fight

I wonder how many deleted messages @0celo7 has

ACuriousMind

Feb 19 at 4:28, by DanielSank

All hail the deleted post King!

2

Yeah, starring quotes is not pretty

3

John Duffield

@BernardMeurer : what idea? Photon effective mass isn't my idea. Nor is slowing down light in glass. Google it.

Danu

Hush now

0celo7

@ACuriousMind who's that

Danu

20:34

Only dreams

0celo7

@Danu is a murderer

Bernard Meurer

@JohnDuffield I was rather referring to that talk about time not slowing down but the light clocks slowing down because light was dun goofing

0celo7

@ACuriousMind why is this starred

ACuriousMind

@0celo7 I thought he's just singing a lullaby

@0celo7 My natural charisma

Danu

Death by boredom

0celo7

20:36

@ACuriousMind ok maybe he's just slipping someone a roofie

Bernard Meurer

We were referring to different thing :) I'm reading the Abrahams-Minkowski thing now

0celo7

@Danu oh cheer up

Bernard Meurer

@Danu Better than death by diabetes I guess

Danu

@0celo7 No, I meant you

0celo7

@Danu huh?

Bernard Meurer

20:39

$SAVAGE$

0celo7

I dun get it

Danu

Pocahontas - Savages - Full Version

►

0celo7

insulting a stupid person is mean

Bernard Meurer

Damn that was quick

0celo7

we can't even understand the insult

John Duffield

20:41

@BernardMeurer : let's talk about problems in physics today. As for [does a non-trivial quantum Yang–Mills theory with a finite mass gap exist?]()en.wikipedia.org/wiki/… IMHO the answer is no. Follow the mass-gap link and see where it says the energy of the vacuum is zero by definition. No it isn't. Any relativist will tell you that.

Danu

I think that's actually a powerful song

ACuriousMind

@JohnDuffield A Yang-Mills theory is not a theory of gravity, so the energy of the vacuum is not an observable, and can be chosen to be zero.

0celo7

I'll listen to it

Danu

@JohnDuffield This is about formal systems defined on Minkowski space

Bernard Meurer

::Grabs popcorn::

Danu

20:43

I'll stop replying now

ACuriousMind

@BernardMeurer I mainly replied there to show you that that's not a valid objection :P

0celo7

@Danu oh wow

yeah it's really good

Bernard Meurer

@ACuriousMind You're like the knowledge version of a sugar daddy

Danu

It's not so far from all this stuff we're seeing again and again about immigrants

ACuriousMind

@BernardMeurer That's...a strange simile :P

0celo7

20:45

@BernardMeurer huh?

John Duffield

@ACuriousMind : here we're getting into that reality v abstraction issue again. The energy of space is not zero. Choosing it to be zero or "defining" it to be zero is Humpty Dumpty physics.

0celo7

lol

Bernard Meurer

"Come here baby let me show you the hamiltonian on my manifold"

0celo7

*cotangent bundle

ACuriousMind

@0celo7 not every symplectic manifold is a cotangent bundle

0celo7

20:47

@ACuriousMind are you sure

ACuriousMind

Yes.

0celo7

in any case, cotangent bundle sounds more like a euphemism

Bernard Meurer

@ACuriousMind Example

0celo7

@BernardMeurer sphere, probably

ACuriousMind

Indeed, the 2-sphere is a counterexample

0celo7

20:48

Oct 29 '15 at 20:30, by 0celo7

@ACuriousMind Is every symplectic manifold the cotangent space of some configuration space?

Bernard Meurer

Holy crap

0celo7

@ACuriousMind I know that all one needs for hamiltonian mechanics is a symplectic manifold

but in physics one usually takes it to be a cotangent bundle

Bernard Meurer

$O(n!^{n!})$

ACuriousMind

You can even relax that to a Poisson manifold! ;)

0celo7

@ACuriousMind oh come on

John Duffield

20:51

Polite cough: anybody for problems in physics?

0celo7

No

let's talk about closed timelike curved and parallel universes

@ACuriousMind do I even want to know what that is

Bernard Meurer

Let's talk about Bill O'Reilly

ACuriousMind

@0celo7 It's basically a union of symplectic spaces, not necessarily of the same dimension

Bernard Meurer

Isn't poisson something like fish in French?

ACuriousMind

@BernardMeurer Yes

But it was also the name of a mathematician

Bernard Meurer

20:53

I can make good wine already

Did he make fish-shaped manifolds?

ACuriousMind

@BernardMeurer No, but his theorems smell like fish

Bernard Meurer

@ACuriousMind Oh snap, you're on a roll today dood

0celo7

@ACuriousMind is the "symplectic form" an inhomogeneous form or something?

ACuriousMind

@0celo7 Nah, you just don't have a symplectic form, just a Poisson bracket

0celo7

and why would one possibly want to use a manifold like that

QoGS?

ACuriousMind

20:56

@0celo7 iirc, one can show that the space of fields of field theories is Poisson but not symplectic

or something like that

John Duffield

@0celo7 : There are no curved parallel universes I'm afraid.

Bernard Meurer

@ACuriousMind Can I get a Meurer bracket?

0celo7

@BernardMeurer No.

Bernard Meurer

I want it shaped like a sideways M

0celo7

@ACuriousMind so it's infinite dimensional?

@BernardMeurer huh?

rotated clockwise or counterclockwise

ACuriousMind

20:57

@BernardMeurer Perhaps. You could also try to convince everyone that the Maurer in "Cartan-Maurer form" was really Meurer

0celo7

lel

he doesn't even know what a Lie group is

Bernard Meurer

Does he have a bracket?

It's a group composed of people who don't tell the truth

Nope

ACuriousMind

@BernardMeurer Isn't that basically a $\Sigma$?

@BernardMeurer no usepackage in MathJax

Bernard Meurer

That's just a pretty E

Just figured that the tough way

I'll call the LaTeX people

tell them to add a Meurer Bracket

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