The h Bar

danielunderwood

12:04 AM

@Blue of course! Meta is where people go to fight/complain!

enumaris

1:55 AM

kachow

user351417

2:31 AM

@rob (or any of the mods) Should I make that chat guide a separate question and answer?

user351417

There are a couple of comments suggesting that. I don't care too much either way.

David Z

3:08 AM

@Chair I would rather have it as a separate question and answer. Otherwise it gives the impression that it's just an announcement or proclamation or something that's already been decided and there's no room for feedback.

user351417

4:10 AM

@DavidZ Done.

Anonymous

@danielunderwood "fight/complain" describes it well. Lots of people talking past each other. :P

user351417

I've moved the content of our chat guide from the question to the answer, so I'd like it if people could vote /comment on physics.meta.stackexchange.com/a/11094

user351417

@Blue @danielunderwood Meta is murder

user351417

(Although the meaning in that context is different)

Anonymous

@Chair Hah, I love that blogpost. :)

Anonymous

4:31 AM

I mean, this sorta speaks of humans in general. We love arguing and "winning" the arguments. Just walking away from a lost cause is inherently difficult.

vzn

speaking of fighting/ "race to the bottom", another story from "late-stage" capitalism... The Thirst for Amazon's HQ2 Is Back and Bleak as Ever splinternews.com/…

Rudi_Birnbaum

5:16 AM

Good morning all!

Anyone here who has some idea about Jahn-Teller effect (or kind if equivalently the Peierls distortion)?

user351417

7:59 AM

@Rudi_Birnbaum Don't ask about asking, just ask!

user351417

Can we pin the link to the proposed chat guide?

user351417

8

Q: The h Bar is always open!

The main chat room for Physics SE has been an active place for a while now, and a lot of you have probably popped in at some point of time. However, some of the regulars recently got the feeling that chat isn't what it once was, and the consensus of that discussion was that codifying a bit of the...

user351417

I was hoping that it would receive some more edits and feedback than it did; hopefully the new layout with a small question and a full-scale answer will help with that.

user351417

Once we have a steady number of votes (since I can't think of a better way to gauge approval), we could add it to the room description.

Avnish Kabaj

@vzn What up with the divorce tho

Anonymous

8:07 AM

@Chair I've deleted my answer and am considering editing some of the points from there into your answer. I've been thinking about this and have come to the conclusion that my answer was more like a penal code. It might be better to keep some things intentionally vague so that users don't go around accusing each other of rule-violations.

Anonymous

I remember cases of you-flagged-me-so-I-will-counter-flag-you-to-prove-my-point in this very chat room. Flags are not meant to be weapons. They're supposed to be shields from inappropriate behavior.

user351417

@Blue I actually thought it was nice to have one answer which focuses on how people should react when they're... unnerved/annoyed. I don't think your answer contradicted ACM's emphasis in your old post about improving chat, but it was quite detailed so I thought it was good to have it as a separate answer.

Avnish Kabaj

1 min ago, by Blue

I remember cases of you-flagged-me-so-I-will-counter-flag-you-to-prove-my-point in this very chat room.

Has it ever gone that bad?

user351417

@Blue I've never seen those, but if you say that they happen, then it's certianly something which should be mentioned. But hopefully that would be there in a separate answer, because the guide itself could be quite positive.

user351417

I think I joined chat after a lot of things... cooled down. I remember some meta posts from april last year regarding chat, but that was a couple of months before I even started peeking into chat.

Anonymous

8:13 AM

@Chair Hmm, I might do that. I will restructure the answer a bit in that case so that doesn't appear as a penal code. Codifying how-to-be-nice and how-to-behave-like-a-decent-human doesn't normally go down well in SE. :)

Anonymous

@AvnishKabaj Yes.

user351417

@Blue On the internet, nobody knows you're a human.

Avnish Kabaj

@Blue o.O

user351417

Heh, I'm at school and images are blocked half the time.

Avnish Kabaj

reddit.com/r/ronmaimon/about

user351417

8:15 AM

Reddit's blocked too :P

Avnish Kabaj

Is this an elite form of sarcasm because the dude's been temporarily suspended till '92

Anonymous

@AvnishKabaj Not 2092; 2292.

Avnish Kabaj

@Chair lol

@Blue oh god

Wtf did he do

200 year ban

What

How does that happen

Anonymous

@AvnishKabaj Don't ask. If you search meta you'll find some pointers. :P

Anonymous

@AvnishKabaj It's basically the max length suspension. The SE software doesn't have a permanent suspension feature.

Avnish Kabaj

8:18 AM

Oh

Anonymous

Chat suspensions have a max length of 3000+ years. :P

Avnish Kabaj

Ohk cool

@Chair IB or something?

CBSE schools are off now

user351417

9:13 AM

@AvnishKabaj Yeah, IB, but I didn't know that CBSE's off now.

Slereah

morning

Slereah

11:00 AM

Woo

just broke 8000 points

Look on my Works, ye Mighty, and despair!

Rudi_Birnbaum

11:25 AM

@Chair thank you! (My question is meanwhile solved but I got another one:)

Take a bound electron in a degenerate state. Suppose the degeneracy is described by a linear combination of two "p-orbitals" (i can define them in case its neccessary) say $p_x$ and $p_y$. Now my question is if the corresponding electron density has cylindrical symmetry or rather a lower one?

And I mean cylindrical symmetry with respect to the $z$ axis.

That would be representations of the $p_x$ and $p_y$ orbitals, isosurface plots, color corresponds to amplitudes. $z$ axis then points upwards.

Our state function would be $\psi=c_1 p_x + c_2 p_y$, with $c_1^2 + c_2^2 = 1$.

My actual point is: What exactly means the degeneracy? Does it mean the electron is in a specific superposition of both or does it mean its in a state that is the superposition in general?

Rudi_Birnbaum

11:59 AM

Let me attempt an answer: Measuring the energy in some cases (high symmetry) does not lead to a "complete collapse" of the state function to a "unique"(?) wave function but instead may leave the state in a (partial) superposition, that only localizes after another measurement.

only localises -> only possibly localises

Emilio Pisanty

@Rudi_Birnbaum yes, that's all correct

Rudi_Birnbaum

@EmilioPisanty, thank you! Now another puzzlement: Suppose we have a symmetric molecule with fixed nuclei = (point charges, implying Bron-Oppenheimer, ...) on symmetry positions but the electronic state being of a degenerate symmetry species.

I have read that it should be intuitive that in such states there will be forces acting on some nuclei forcing them away from the symmetry positions since the electron density, thus the the electric field will be distributed in a lower symmetry than the molecule had.

I find that puzzling, since one could wonder what the driving force for that would be as long as the electrons are in the supersposition.

The question would be: What is the symmetry of the electric field when the electrons are in the degenerate state?

Emilio Pisanty

12:56 PM

@Rudi_Birnbaum reference?

it's hard to give an answer - the description you've given is too vague to know exactly what you're talking about

There's a slightly better-than-even chance that they were talking about the Jahn-Teller effect

Jahn–Teller effect

The Jahn–Teller effect (JT effect or JTE) is an important mechanism of spontaneous symmetry breaking in molecular and solid-state systems which has far-reaching consequences for different fields, and it is related to a variety of applications in spectroscopy, stereochemistry and crystal chemistry, molecular and solid-state physics, and materials science. The effect is named for Hermann Arthur Jahn and Edward Teller, who first reported studies about it in 1937. == Simplified overview == The Jahn–Teller effect, sometimes also known as Jahn–Teller distortion, describes the geometrical distortion of...

but it's hard to be sure

Rudi_Birnbaum

Emilio Pisanty

oh, goodness

reference?

what year is that even from?

Rudi_Birnbaum

Yes its of course about JT. Ref. for that particular is 10.1007/BF00525841

sci-hub.se/10.1007/BF00525841

Emilio Pisanty

@Rudi_Birnbaum any particular reason why you're going to 1960s literature for this?

Rudi_Birnbaum

Yeah it was when German was still a scientific language in Physics.

Because its still refered to in current literature and they

introduce an idea for a proof of the JT that is kind of the most general to-date.

Emilio Pisanty

1:01 PM

still, surely there are better references

but anyways

no, there are no forces

Rudi_Birnbaum

Also in general I tend to view "old" literature as not bad per-se.

In deed some of it is better then some current.

Emilio Pisanty

or at least, there are no forces if the nuclear positions are exactly symmetrical

the energy landscape looks kind of like $V(x) = x^4-x^2$, where $x$ is some reaction coordinate

with $x=0$ representing a symmetric molecule

and the two directions reflecting the two possible ways the symmetry can be broken

so, if the molecule starts off exactly symmetrical, then there's no way to break the symmetry

Rudi_Birnbaum

@EmilioPisanty yes.

Emilio Pisanty

but if there's even a slight perturbation, then that will self-amplify until it reaches a stable configuration.

@Rudi_Birnbaum It's not bad per-se, but if you want help with it from other people, might I suggest trying the German-Language 1960s Quantum Physics chatroom?

Rudi_Birnbaum

Oh is there one?

great!

Would there be one for the 20ies also?

Emilio Pisanty

1:09 PM

@Rudi_Birnbaum Good luck finding help =).

Rudi_Birnbaum

I mean if there is a an old publication stating some theorem, that should be right, which is however not stated later and it turns out to be interesting or questionable wouldn't that qualify for a chat subject independent of its age or language? In Maths e.g. I think it would be no question. Now it happens its on top German, so what. there are significant publications in my own field in French or Russian I don't speak both. But I wont' bycot them

Emilio Pisanty

@Rudi_Birnbaum who said anything about boycotts? You asked an unclear technical question, and the only reference you gave is in German; I can help with the technical question if you're willing to clarify it, but that level of old German is beyond me. If you're not willing to switch to references that your interlocutors can use, or clarify the technical question in your own words, then I wish you luck finding other interlocutors.

Rudi_Birnbaum

I think its a misunderstanding, I am not not willing, it just happend that there are no references in other languages I am aware of.

Emilio Pisanty

... though given the aggression, I'm not particularly keen on carrying on this conversation.

Rudi_Birnbaum

@EmilioPisanty that agression: "1960s Quantum Physics chatroom?

Emilio Pisanty

1:15 PM

@Rudi_Birnbaum if you want to chat science, start now. Otherwise, good day.

Rudi_Birnbaum

I don't think its the type of second order effect in $x$ your example is about. $x^4 - x^2$. It should be about the (first order) JT effect in my understanding.

because degeneracy is a condition for the first oder JTE, not for the second order one.

So there should be another argument.

Jake Rose

2:45 PM

@JohnRennie you around?

what does this sentence mean? “Notice that eigenvectors are undefined with respect to complex multiplication”

Anonymous

3:09 PM

@JakeRose Eh, you're working on a vector space (Hilbert space) structure.

Anonymous

You just have scalar multiplication and vector addition defined there. Multiplication of vectors is not defined.

Anonymous

And, ugh. That sentence is just cringeworthy. One of the reasons you shouldn't learn QM from physicists. :P

Slereah

What is "complex multiplication" supposed to mean in a vector space context?

Anonymous

@Slereah I'm not really sure what it means. I assumed they were referring to "multiplication" of eigenvectors.

Anonymous

It's just too vague to mean anything...

Sir Cumference

3:24 PM

I guess if we're looking at a vector space over C? Or maybe the context deals with the complex numbers over R?

Anonymous

@SirCumference Well, you can either take a real Hilbert space or a complex Hilbert space.

Slereah

Well there are "multiplications" of vectors

inner product and direct product

I guess there is no commonly defined product of two vectors giving another vector, certainly

Anonymous

@Slereah Yeah, that's my point basically.

Sir Cumference

@Blue Well yeah but I don't usually interpret "multiplication" as "inner product", but who knows

Anonymous

@SirCumference Neither do I. Which is why they're calling it "undefined" perhaps.

Anonymous

3:32 PM

In our usual quantum mechanics we only deal with complex separable Hilbert spaces though.

Anonymous

So talking about a vector space structure over $\Bbb R$ isn't quite useful here.

Sir Cumference

oh i assumed it was just a linear algebra class he was doing

Rudi_Birnbaum

@JakeRose Maybe it means they are eigenvectors up to a constant complex number?

Anonymous

@Rudi_Birnbaum What's the significance of the term "undefined" in that case, though?

Rudi_Birnbaum

So if $\mathcal{O}\vec{v}=\lambda \vec{v}$ then also $\mathcal{O}\vec{v'}=\lambda \vec{v'}$ with $\vec{v'}=c \vec{v}$.

with a complex number $c \ne 0$.

Sir Cumference

3:35 PM

what a mystery

Rudi_Birnbaum

@Blue dunno, just a guess. A bit of context could help as well.

Anonymous

Meh. Jake Rose should drop the class. :P

Jake Rose

3:46 PM

@Blue that won’t be happening anytime soon...

the lecturer is fantastic, but obviously sometimes notes can be unclear (as mathematicians notes can be) which considering its a 200+ page document is reasonable

vzn

4:05 PM

@AvnishKabaj eyepopping/ eyewatering $70B most expensive in history of marriage! ... he seems to have a rivalry going with the president too... burning tabloid fodder for months at least if not years :o o_O

John Rennie

4:17 PM

@JakeRose I think this is a tortuous way of saying that for any complex number $C$ the eigenvectors $V$ and $CV$ are identical.

That is, multiplying an eigenvector by a complex number does not change it.

This is because the eigenvector picks out a direction in the Hilbert space but its magnitude is not meaningful. It is what we call a ray in the Hilbert space.

Rudi_Birnbaum

4:42 PM

@JohnRennie yeah i also think so see 7 posts above.

Sir Cumference

4:54 PM

I miss the days when books put arrows over Euclidean vectors. Made things easier to keep track of

DanielSank

5:09 PM

Shamelessly sharing an answer I wrote last night because I think the topic is interesting and not very generally well known:

2

A: Is there a physical limit to memory reading and writing speed?

Consider a quantum system with two levels separated by an energy $E = \hbar \omega$. In a sense, this is the smallest possible physical system from the point of view of information content. When a two level system can be accurately controlled, measured, and interacted with other two level systems...

Abcd

@JohnRennie Are you there for 1 minute?

John Rennie

@Abcd hi, yes I'm around

Abcd

Node start;
Node t = start;

@JohnRennie This means that t is pointing at the same place where start is pointing, right??

John Rennie

Yes

(at least I think so ...)

Abcd

@JohnRennie So if we change where start is pointing after this step, then what will happen?

John Rennie

5:20 PM

What do you mean by change where start is pointing?

Do you mean change some member variable of the start object?

Abcd

@JohnRennie wait

        Node n = new Node();
        n.setData(d);
        Node t = start;
        if( t == null)
        {
            start = n;
        }

@JohnRennie I mean the start= n part

John Rennie

If start is null That code will leave t equal to null and start will be equal to the new node. So t and start will not refer to the same object.

Zerix

@JohnRennie what is the difference between vaporisation and boiling? Are they same

John Rennie

@Zerix no

Zerix

What's the basic difference between them

John Rennie

5:28 PM

It's complicated. Ask me tomorrow.

Zerix

Okay

John Rennie

Actually I think I answered question on that. Let me have a look ...

Zerix

Searching Quora kinda confused me on this

John Rennie

@Zerix I was thinking of this:

28

Q: Why does temperature remain constant when water is boiling?

As I understand it, during boiling the input of heat destroys or re-arranges the hydrogen bonds. It is used, in other words, against the potential energy of the intermolecular bonds. But if some hydrogen bonds between molecules are destroyed then why is the kinetic energy of these particular mol...

thermodynamics energy temperature physical-chemistry phase-transition

Abcd

@JohnRennie last doubt of 1 min

John Rennie

5:31 PM

which is kind of related to your queston but not exactly the same.

@Abcd yes?

Abcd

@JohnRennie Can t.setNext(n) be inside else after while?

John Rennie

@Abcd reading ...

@Abcd t.setNext(n) is in the wrong place.

Abcd

oh?

John Rennie

It should be inside the else clause after the while clause.

Abcd

right, thats where I thought it should be. Thanks.

John Rennie

5:38 PM

@Abcd like that

Abcd

ya ok

Avnish Kabaj

5:57 PM

@vzn The 70B is that speculated or an official statement is out?

Anonymous

@Chair What does "real estate" mean in "Avoid rapid, short messages and txt spk/l33tspeak. These are often hard to read and they take up valuable real estate." here?

enumaris

kachow

Avnish Kabaj

@Blue Real estate was a meme

Oh lol

He did sneak in one

knowyourmeme.com/memes/its-free-real-estate

Anonymous

@AvnishKabaj I'll invoke Poe's law and say that it's a terrible place for a meme. ;)

Avnish Kabaj

Poe's law is an adage of Internet culture stating that, without a clear indicator of the author's intent, it is impossible to create a parody of extreme views so obviously exaggerated that it cannot be mistaken by some readers for a sincere expression of the parodied views.[1][2][3] The original statement, by Nathan Poe, read:[1]

ACuriousMind

6:07 PM

@Blue "real estate" = "screen space"

Anonymous

@ACuriousMind I was suspecting that but it's not really clear from the context.

Avnish Kabaj

He wanted to make puns

Anonymous

Also, "real estate" = "screen space" is not standard usage AFAIK.

Avnish Kabaj

I say it was a reference to the meme

ACuriousMind

@Blue Like "sockpuppet", it's a common term on the internet that often isn't clear from context.

Anonymous

6:09 PM

Maybe we could add a link then.

ACuriousMind

I agree it should probably be better avoided in a text explicitly intended for newcomers

Avnish Kabaj

@Chair

enumaris

hmmm

big boss coming today

PM 2Ring

It's not just screen real estate though. It's also wasteful of server space, since each message is stored separately. Sure, it's only peanuts in this day & age, but it all adds up.

Anonymous

6:34 PM

It's not just "server space" either. It's also a waste of real real estate as those servers occupy space in buildings in the real world too. It all adds up.

vzn

6:49 PM

@AvnishKabaj he apparently has no prenuptual agreement (amazon founded ~1yr after getting married) and thats half his net wealth almost entirely in amazon share value... bezos is #1/ 1st in history to reach over $100B forbes.com/billionaires/#682860a2251c

Anonymous

@DavidZ No, strike that last one, chat.stackexchange.com/transcript/message/49023200#49023200 suggests that we should focus on the consensus of chat regulars instead. — Chair yesterday

Anonymous

@Chair I think it's better to go with the vote count. The main chat is public property and any user with >20 rep has the privilege to use it.

Anonymous

Chat regulars shouldn't have any "grandfathery" over the room. Although, of course, we are the ones framing the policies --- because someone has to take the responsibility and initiative.

ACuriousMind

How would we determine the vote count after which we consider "officialness" to have been reached? I think the usual way in which posts achieve faq status is a) no one raises a serious objection to the current state of the post and b) the moderators agree to add the faq tag to it.

Anonymous

@ACuriousMind 1. Yeah, I've heard that point several times on our meta too. In reality, vote counts aren't in a state of constant flux and do saturate after a certain time...usually one or two weeks suffices. 2. Yes, the moderators do need to agree with it or else it wouldn't get passed as a policy. I'm hoping that in this case they will. 3. If there's any serious objections we should obviously discuss that. I don't see any such objection yet and I'm hoping it will remain that way.

ACuriousMind

7:03 PM

@Blue I'm not saying that "votes are constantly changing". I'm saying that it is not clear that a post with 30 upvotes is more or less worthy of being "official" than a post with 10 upvotes. The number of votes depends on factors external to post quality or usefulness, such as how many people are interested enough in the topic to begin with.

Anonymous

@ACuriousMind While that is true (votes can mean different things on meta), I don't know of any better measure for understanding whether a certain policy should be made official. If there is, I'd be interested to know. (As I said, moderator consent is an important aspect of this too, yes.)

ACuriousMind

As I said, the best measure is whether there are strong competing viewpoints. It's pretty safe to make something official to which the strongest objection was "Eh, I'm not sure we urgently need this, but whatever", it's pretty hard to make something official to which there is a sizable fraction of users going "Oh no this will doom us all".

That doesn't mean it's not sometimes necessary to make policy that's unpopular with some users, but it's something that needs much more consideration.

Anonymous

@ACuriousMind Yup, I do agree with that (see my point number 3). I'm just against Chair's comment which says that we should solely go by the opinions of the room regulars. The site users who aren't chat regulars should have just as much say in this, because they too have the privilege to use chat.

Anonymous

In other words, a community becomes unapproachable fast, if there's too much in-group favoritism. I don't want that to happen here.

ACuriousMind

@Blue I agree, but I think you could be more charitable than to equate Chair's "focus on" with "go solely by". The original idea behind these rules, as I understood it, was to write down what "unwritten rules" we basically have always tried to adhere to here to some degree. Of course a regular can evaluate better whether these written rules reflect lived practice, that doesn't mean a non-regular's objections should be ignored entirely

I emphatically do not view this as an attempt to make new policy out of thin air (which was a debacle when we tried it a while back, but which I don't want to rehash here).

2

Anonymous

7:13 PM

> I think you could be more charitable than to equate Chair's "focus on" with "go solely by"

Anonymous

True. I think I could have worded it better. Sorry for that.

Anonymous

@ACuriousMind Agreed, yeah.

Anonymous

7:26 PM

@ACuriousMind Unrelated: I'm a bit confused about why my recent "no longer needed" flags got dismissed. Any idea? I was thinking we should keep that comment section a bit clutter free as it's a site-policy thread and will be used for reference in the future. Not that I mind much, obviously.

ACuriousMind

@Blue The latter part of John McVirgo's comment is not obsolete, as it makes a point unrelated to the Q/A split, and I didn't want to remove Chair's response to it without removing it, either.

Anonymous

@ACuriousMind Okay, got it. Thanks.

ACuriousMind

(If there was a way to mark a comment flag as helpful without deleting the comment, I'd have done that, but there's no way to do that)

Anonymous

There's the option of deleting and undeleting the comment, which marks the flag as helpful. But yeah, that's some extra work. No worries.

Joshua Lin

9:58 PM

Is anyone free to review GR with me :'(

Anonymous

@JoshuaLin Define "review"?

Joshua Lin

Does it go something like this?
GR starts with some 4-manifold; equipped with lorentz metric. Metric gives rise to a unique connection that is compatible in some sense; Levi-Civita. So at this point, if we are given manifold+metric, we can already talk about particles moving around as curves in the manifold and can describe their 4-vectors and stuff

'review' in the sense that I used to know something but I've forgotten it, I'm confused about matter and stuff

So like how do we start doing physics? Given a manifold+metric; we don't have a notion of how particles/matter evolves on the manifold right? There is some additional data? I'

Not even quite sure how 'matter' is defined - I want to say you take some bundle over the manifold (maybe principle, to reflect gauge? cant remember how it works) - then fields are just sections of this bundle; and they evolve according to some specified Lagrangian?

The Lagrangian also gives you the stress-energy tensor by Noether; which in turn by Einstein's equation says something about the curvature of the manifold? Does this make sense or nah

ACuriousMind

@JoshuaLin It depends on what sort of physics you want to do. If you want to do the physics of single particles moving on this background metric, you can write down an action for how that particle moves on this manifold, cf. e.g. this answer.

Joshua Lin

thanks, I will take a look

ACuriousMind

If you want to do physics as in "how does the metric evolve under its interaction with matter", then you start from the Einstein-Hilbert action and add terms to the Lagrangian for the other fields you want to look at, e.g. you can add the Lagrangian for the free EM field, and you get the Einstein equations relating the Einstein tensor as a function of the metric to the stress-energy tensor as a function of the rest of the fields

Joshua Lin

10:04 PM

so the fact that particles follow geodesics is a postulate of GR right? (can't believe I forgot that..)

Oh I think I understand now; I think I'm used to non-GR settings where the background metric is fixed and so Lagrangian -> Action gives you how particles and things evolve; but now we have both the background spacetime + matter fields evolve in time, so total lagrangian involves both of them, and solving for them gives me how the spacetime + matter evolves in time?

ACuriousMind

@JoshuaLin It's tedious to argue about what the "postulates" of a physical theory are because you almost always can take some statement that is equivalent to it but rather different at first sight as the postulate instead :P

Joshua Lin

:-) haha yeah I guess
wait so what mathematical objects are matter fields/other fields (like EM) actually? Are they really sections of some bundle over the manifold?

ACuriousMind

@JoshuaLin Yes, formally all the fields have to be sections of appropriate bundles

Joshua Lin

oh ok cool - do the bundles reflect the gauge of the theory? So working with EM field, is it just a section of a U(1) bundle over the manifold?

hmm this discussion makes it a lot more interesting to me what would happen if the Lagrangian evolution gives us singularities in the future... the naive formulation of the model seems to just break down then

ACuriousMind

@JoshuaLin No, not quite. The gauge potential of a gauge theory with gauge group $G$ is a connection form on a $G$-principal bundle over the manifold, and the corresponding field strength is a section of the associated bundle in the adjoint representation of $G$. I talk about the bundle structure of gauge theories e.g. in this answer of mine

Interestingly, you can view GR itself as a gauge theory, with the Christoffel symbols as the gauge field, see more answers of mine: physics.stackexchange.com/a/176082/50583, physics.stackexchange.com/a/346812/50583

Joshua Lin

10:19 PM

Reading through your first answer; it seems that to do gauge theory on spacetime - the bundle that we take has fibers the lie algebra of the associated (gauge) lie group of the theory?

Sir Cumference

Whoever thought 9am is a reasonable time to teach physics everyday is my enemy

Joshua Lin

wait let me keep reading

side point - @SirCumference are you at Berkeley? your profile has a quote by Chris White that for some reason sounds like someone at berkeley

wait no Chris White was a prolific answerer on stackexchange right? nvm lol

ACuriousMind

He was, and he wasn't at Berkeley as far as I remember, though he might have gone there as a postdoc :P

Sir Cumference

10:44 PM

@JoshuaLin Nah I just like the quote :P

Transcript for