The h Bar

heather

12:19

pretty quiet today.

user223506

HI!

heather

hello =)

user223506

how are you?

heather

good, how about you?

user223506

not too bad - researching, relaxing my injured leg and answering questions - like this physics.stackexchange.com/a/306113/140434

user223506

12:25

you?

heather

reading, learning, relaxing.

hope the leg gets better!

user223506

that's the best way

user223506

it should - the bleeding has stopped and no aliens have emerged

heather

lol

user223506

fell down some stairs - the ghost of newton pushed me

heather

12:29

ack, darn it newton.

what is this, the 20th time you've gone after a scientist?

user223506

he always pushes me down, up and sideways across stairs

user223506

sometimes, the absence of photons in my shadow trips me over

heather

::shakes head::

that must be troubling me

instead of tripping over my own feet, i'm tripping because of Newton and my shadow.

user223506

true... i am waiting for the day that I levitate instead of landing on my derriere

user223506

Hello @JohnRennie!

heather

12:38

i can't wait for the day i become a padawan

@JohnRennie, hello!

John Rennie

Afternoon (UK time)

user223506

@heather LOL

John Rennie

@heather I was wondering if you'd be interested in talking abour GR some time, though that time is probably not when you need to rush for the bus :-)

heather

@JohnRennie i would be very interested, but yeah, this morning would probably not be the best time.

user223506

Could GR help catch a bus?

John Rennie

12:40

Put the bus near a black hole and it will run slow :-)

heather

@Doc "use the force..."

@JohnRennie YES!!!

user223506

@heather oh I do, and then the force pushes me down the stairs

John Rennie

@heather what I could usefully describe is what a metric is and how we use it. The gory details of the maths used in GR aren't my strong point.

heather

@Doc to quote Han Solo, "that's not how the force works!" =P

user223506

@heather so true

heather

12:43

@JohnRennie that would be a most edifying conversation.

Sir Cumference

Morning

user223506

but to quote me:

heather

@SirCumference hello

John Rennie

@heather If you're interested maybe the weekend is best. Our schedules don't overlap much during the week.

user223506

I don't obey the laws of physics, they obey me

user223506

12:43

Hi @SirCumference

heather

@JohnRennie okay, sounds good.

@Doc how about the laws of star wars?

user223506

@heather they obey me too

heather

nice =)

user223506

especially as I am very Chewbacca in appearance

user228700

Hi, guys :-)

user223506

12:46

hello @Kaumudi.H

John Rennie

@Kaumudi.H Hi. I have a potentially interesting link for you ...

user228700

@JohnRennie Hmm. I'm studying now, will it derail me?

John Rennie

I saw this on the BBC News site yesterday

@Kaumudi.H Yes :-)

user228700

x'D I'm interested to know what they taste like.

user228700

1 sec.

John Rennie

12:52

MacDonalds aren't fools. They will have got people to taste them and check they were popular.

I'm still not sure about a McDosa though :-)

user223506

if they make a McPhysics burger, then I'll be impressed

heather

@Kaumudi.H, hello

John Rennie

@Doc A Big Bang Mac!

3

user223506

@JohnRennie with a side order of photons

heather

plus a dark matter smoothie

user223506

13:02

and a caramel soundwave

heather

a spacetime brownie, perhaps?

user223506

yes please!

user223506

now I am hungry

user228700

^ Exactly.

user223506

lol

user228700

13:06

@JohnRennie buzzfeed.com/sahilrizwan/…

heather

good day all.

gotta get on the bus =/

John Rennie

@heather Have a good day :-)

user228700

@heather Have a nice day, bye :-)

John Rennie

@Kaumudi.H I would reserve judgement until you've tried it. As I say MD aren't fools. Everybody criticises MD in the UK, but actually I think Big Macs are really nice :-)

user223506

have a great day @heather!

user228700

13:09

@JohnRennie I too want to wait till I've tried it but boy, it does sound like a bad idea. Molaga podi sauce sounds kind of terrifying on a burger.

John Rennie

@Kaumudi.H Oh I don't know ...

user228700

I've never been to McDonalds till now so when the day comes, I'll try it and let you know.

user228700

@JohnRennie Of course you don't know :-P U haven't had dosa with molaga podi, have u?

John Rennie

@Kaumudi.H No. Is it good?

user228700

It's my favorite food in the whole world :-) It's funny, we never went there--"What's your favorite food?"

John Rennie

13:12

Well the burger is actually a vegetable pattie, so it's a spicy sauce on vegetables. That seems potentially nice to me ...

user228700

No, it's not a sauce.

user228700

This is what molaga podi looks like:

user228700

user228700

Dyou see the brown stuff? Yep, that.

John Rennie

The brown liquid or the brown powder?

user228700

13:14

Well, the powder is made and then we add oil to it to make it a liquid and then we eat dosa, idli, etc with it.

user228700

So it's texture is actually kinda grainy.

user228700

Although, these people have promised "sauce" so I guess I'll just have to wait...

John Rennie

Ah. Oh well, I'd try the MacDonalds burger anyway. Like I say, they do know what they are doing.

What is the white stuff? A cake made from ground rice?

user228700

@JohnRennie Google idli :-)

John Rennie

Aha, not so different from an English steamed pudding.

user228700

13:16

Oh, really? Pudding? I'm a little dubious .__.

user228700

It's not sweet or anything.

Secret

they look like steamed buns in chinese cuisines

user228700

It tastes like nothing, actually. U can't eat it on its own. Well, no, some people do but not me.

user223506

I better go y'all - got to rest my ruined leg

John Rennie

This is a steamed pudding

It is traditionally sweet, but it can be made as a savoury meal instead.

But it uses wheat flour not rice flour.

Secret

13:18

IMO steamed pudding is a bit more tender than this and steamed buns

user228700

Ah, wheat is a lot different from rice in taste.

John Rennie

True ...

user228700

You should visit India again :-)

John Rennie

See, I told you this would distract you from your work :-)

user228700

:-) No, I had to take a break now anyway.

John Rennie

13:19

Oh no, a moderator has turned up and we're talking about food again :-)

user228700

I'm not kidding tho, you really should come and taste everything :-P

user228700

@JohnRennie Meh :-P

Secret

Most starchy pudding or bun like food have a mild sweet taste. I sometimes like to eat those by themselves

John Rennie

I must admit that first of those food tour of India videos you linked left me really hungry.

user228700

@JohnRennie Oh, u can find so many (better) of those online :-D Might tempt you tho.

user228700

13:21

If u come, I can show you around! :-D

user228700

Did u see the one with what's his name, um, that guy who hosts "Hell's kitchen" or something along those lines..?

user228700

@JohnRennie Yeah, Gordon Ramsay! Did u see the one with him? In India?

John Rennie

Can't remember. I don't think so.

But what I liked about the food tour videos is that they are everyday street food not high cuisine.

user228700

Gordon's.Great.Escape.India.E01

►

user228700

There are about 3-4 episodes and he explores not only street food but also like, food they make in villages and all.

John Rennie

13:28

That looks quite fun. The YouTube link you posted is blocked in the UK for copyright reasons but I can probably download it somewhere.

user228700

@JohnRennie Oh :-| Yeah, probably. Maybe just google "Gordon Great Escape India". And yeah, it's pretty amazing.

user228700

He even cooks with a bunch of Indian caterers. Once even for a birthday in the slums of Mumbai. Yeah, it's amazing.

John Rennie

Oh well. I have to go into town now. Got a franking machine to configure.

MartianCactus

@Kaumudi.H what does "oh so pleasant" mean?

user228700

@JohnRennie Uh, OK. See u tomorrow :-)

user228700

13:36

@MartianCactus Well, um, that phrase, on its own, means exactly what it sounds like--very pleasant. In this context (I assume that you're referring to my "status" or whatever), it means, well, if you're really interested, I urge you to give this a read:

MartianCactus

?

user228700

Sorry, gimme a minute.

MartianCactus

k

user228700

@MartianCactus reddit.com/r/intj/comments/3c7ydw/…

MartianCactus

oh thx!

ACuriousMind

13:50

@Kaumudi.H Ugh, most of these "psychological types" are utter nonsense. People are different, but not so easily sorted into categories (for one, most of these type tests aren't stable - retaking them does not reliably yield the same result). I would view anything that takes their existence uncritically for granted with much suspicion.

Secret

Type tests don't describe me well. While interestingly they are quite consistent for my case, the ouverall result is always a superposition of all the personality traits available in the test

ACuriousMind

The sentiment that you don't need to be a joyless prick when you're smart is valuable regardless, though :P

user228700

@ACuriousMind Yep.

Secret

also on that note, the myer briggs test is now ruled out, but the big 5 personality metric is still creditable and in use in many social psychology assessments

Balarka Sen

@ACuriousMind well it kinda depends on the definition of joy for that particular person

but yeah everyone should do whatever that makes them happy

ACuriousMind

13:55

@BalarkaSen Well, sure, if you're a highly intelligent person who only delights in brutal murder then I'd prefer you stay joyless :P

Balarka Sen

Point.

Secret

For me, happiness is simple: As long people or any necessary tasks don't stop me from researching interesting problems in the natural sciences, I am happy

Right now (and in the coming week), I would have been either continue my crunching on munkres or QFT if not because of the need to prepare the very boring driver knowledge test

Balarka Sen

I like watching movies, reading stuff and playing video games along with whatever I do too

user228700

@BalarkaSen That's...not exactly the point of the original statement or whatever but sure.

Balarka Sen

Yeah I was making a tangential remark

Secret

14:24

OMG and O...M...G....

Secret

15:36

in Mathematics, 2 mins ago, by user129412

@Secret Yes, it is quantum computing related. This specific data (calculated from a model, so not measured, although I am an experimentalist) is about what the effect of a specific noisy environment is on the decay of phase information of a two level system

Hmm, quantum noise, sounds like something that @DanielSank will be interested

Johnathan Ralls

15:57

is this an alright place to ask a question?

As I understand light radiation it is only able to heat an object to approximately the heat of the lights source. If the light were to pass through a medium that was hotter than its source would the light "pick up" more energy?

DanielSank

@Secret I know that stuff!

@JohnathanRalls essentially, yes.

Johnathan Ralls

could you elaborate?

DanielSank

If you have light generated by a thermal source, e.g. a star, then that light has a certain amount of power at each wavelength.

The total power summed up over all wavelengths increases if you increase the temperature.

All matter radiates light in accordance to it's temperature.

So whatever medium you have radiates, and if it's hotter than the original light source, then it radiates more.

Now, there's one more detail.

Johnathan Ralls

what's the detail?

DanielSank

en.m.wikipedia.org/wiki/Emissivity

A perfect absorber/radiator is called a black body.

Johnathan Ralls

16:12

i believe that relates to radiation generated from heat by the object applied by an outside source, in this case a light. i was wondering about the effect of the "original" light either passing through the medium or reflecting off of the medium.

if i am mistaken, could you tell me how?

DanielSank

The original light goes unchanged, except of course for the fact that some is absorbed by the medium if the medium isn't perfectly transparent.

However, the medium adds it's own thermal radiation too!

Johnathan Ralls

so a cooler light would in effect be absorbed and cool the hotter object?

unfortunate to my original thought, but neat nonetheless

DanielSank

No, why do you think cooler light would cool an object?

Johnathan Ralls

i had that thought because if an object had a temp of X+5, and the light source had heat X+1, the light passing through/reflecting off of the object the light would be absorbed to some degree. the area that absorbed the light would then be receiving a "cooler" energy than the area surrounding it attempting to reach temperature X+1

DanielSank

That's not how it works.

Johnathan Ralls

16:20

that's why i'm asking! :D

DanielSank

Suppose we have a perfectly transparent medium.

Johnathan Ralls

than no energy would be transferred from the light, right?

DanielSank

Transparent means the medium does not interact with light!

Johnathan Ralls

right

DanielSank

@JohnathanRalls yes, so a perfectly transparent medium wouldn't radiate at all.

Johnathan Ralls

16:22

but that is not practical

DanielSank

It's like it's not there.

@JohnathanRalls of course not.

Johnathan Ralls

so how about a partially trasparent medium

DanielSank

Ok now suppose we have a completely opaque object.

Johnathan Ralls

it will either absorb or reflect, but will not allow light to pass through

DanielSank

That thing is called a black body, obviously because a completely opaque object looks black.

Johnathan Ralls

16:24

again though, not practical

DanielSank

Yes but let's understand the two extreme cases!

Johnathan Ralls

one will take in all energy from the light, the other will not interact at all

DanielSank

Right, but the one that takes all energy also radiates energy.

9

Q: Why is black the best emitter?

Why are emitters colored black better emitters than other colors? Why is white a worse emitter?

Johnathan Ralls

i see why we are talking about different things. in most cases the medium would be solid.

DanielSank

Ok

Johnathan Ralls

16:27

what about a plasma

DanielSank

Why would a plasma be special?

Johnathan Ralls

it would be mostly transparent, and as a medium i am unsure how it would interact with a light

DanielSank

For any medium, the more strongly it absorbs incoming radiation at a certain wavelength, the more it radiates it's own thermal radiation at that wavelength.

Johnathan Ralls

how strongly does plasma absorb incoming radiation?

DanielSank

I have no idea.

Johnathan Ralls

16:30

seems to be the next step for me then haha

DanielSank

I've never studied plasma.

Johnathan Ralls

have you studied how a gain medium interacts with light to focus it into a beam?

Sir Cumference

@DanielSank You see the batman signal I made for ya?

anonymous

@JohnathanRalls This article (adsabs.harvard.edu/full/1960MNRAS.120..231S) might answer your question.

Johnathan Ralls

thank you anonymous

ACuriousMind

16:33

-1

Q: Visual of De Broglie pilot wave

This video shows a visual of the pilot wave with a macroscopic walker - https://www.youtube.com/watch?v=WIyTZDHuarQ&t=199s Does it have any significance in context of quantum mechanics. Specially it shows how the pattern is built "over time" (between 2:15 and 3:15). This seems a duplicate of an...

quantum-mechanics bohmian-mechanics

^on-topic?

DanielSank

@SirCumference yes it's amazing

@JohnathanRalls nope

Sir Cumference

@DanielSank Well, now we got one for you, @JohnRennie, @ACuriousMind and @BernardoMeurer (though I'm not sure who will use that one)

DanielSank

@SirCumference where are they (link)?

anonymous

@JohnathanRalls What is a "gain" medium ?

Sir Cumference

@DanielSank Well, John Rennie's is on the starboard

John Rennie

16:36

@SirCumference All good fun, though just pinging me will work fine :-)

DanielSank

@ACuriousMind it's a duplicate, isn't it?

Johnathan Ralls

@anonymous it is a lasing medium, active laser medium.

Sir Cumference

DanielSank

^ amazing

Johnathan Ralls

it goes between a fully reflective surface and a partially reflective surface to "organize" light from a pump in a sense

Sir Cumference

16:37

@DanielSank @obe actually made a vector graphic

anonymous

@JohnathanRalls It is same as asking how a laser works. There are thousands of articles on lasers which you can find by searching online.

Sir Cumference

@SirCumference gyazo.com/cb3d15da898ed7ea06e83e0d3178d8b9

ACuriousMind

@DanielSank of which question?

Sir Cumference

He redrew it entirely

Johnathan Ralls

@anonymous you are not wrong, but my question is very specific to the type of medium

DanielSank

16:38

in Mathematics, 18 mins ago, by user129412

@DanielSank I was, but not on an interesting level. Trying to guess a functional dependence of some curve, like a proper scientist.

@ACuriousMind I don't know but OP says "this is a duplicate"...

ACuriousMind

Yes, but they didn't link a question

DanielSank

Indeed.

anonymous

Self-focusing

Self-focusing is a non-linear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. A medium whose refractive index increases with the electric field intensity acts as a focusing lens for an electromagnetic wave characterised by an initial transverse intensity gradient, as in a laser beam. The peak intensity of the self-focused region keeps increasing as the wave travels through the medium, until defocusing effects or medium damage interrupt this process. Self-focusing of light was discovered by Gurgen Askaryan. Self-focusing is often...

ACuriousMind

There are other questions about the hydrodynamical analogue but none is a suitable duplicate since I'm rather uncertain what this question actually asks

Johnathan Ralls

@anonymous i've glanced over that article before but with reading more in depth it seems my scenario would fit, with some modifications

obe

16:49

hiii

@SirCumference why did you ping yourself lmao

Sir Cumference

@obe I have a userscript that adds a reply button for your own posts :P

Just in case I want to follow up

Ok, anyone want to test a userscript I wrote?

It adds a design to Astro SE

::whistles::

Johnathan Ralls

::claps::

ACuriousMind

::stomps::

Johnathan Ralls

::getsswifty::

obe

@ACuriousMind what's the most interesting topic you learned in physics so far that is at most 1st year grad level?

I need ideas for a project

ACuriousMind

17:04

What kind of project?

Johnathan Ralls

i bet it's a physics one

ACuriousMind

Also, I have genuinely no idea what level "1st year grad level" is :P

obe

@ACuriousMind like the level of peskin/schroeder qft at most

preferably the first half

Johnathan Ralls

you could try to build one of those ultrasonic "tractor beams"

ACuriousMind

@obe Okay, so what kind of project?

obe

17:17

@ACuriousMind research a topic (or a topic you already know) and teach it to someone.

Bernardo Meurer

@ACuriousMind Teach me

Johnathan Ralls

@ACuriousMind No teach me

Lu Bu

17:33

So if we have a 5th degree polynomial Q(x) with a zero at x=-1
then we know it can be written as a product:
Q(x) = P(x) * (x+1).
Because in the reals the highest degree of irreducibility is
two.
Does this then mean that Q(x) cannot generate any primes.

I don't know if this is a weird question, because i really shouldn't
delve into these at this point, but im still gonna ask it.

ACuriousMind

@obe Well, ordinary QM is full of interesting situations which usually are introduced in more complicated field-theoretical settings: Quantization of a particle on a ring, Berry phases, various approximations and their validity (e.g. WKB), path integrals with solitons/instantons, supersymmetric systems...

@LuBu What do you mean by "$Q(x)$ cannot generate any primes"?

I don't know what it means for a polynomial to "generate primes".

@BernardoMeurer what should I teach you?

Bernardo Meurer

@ACuriousMind Pick something you like in Physics

Lu Bu

@ACuriousMind Well if you plug in x's you won't get any primes out.

Johnathan Ralls

what is function P equal?

ACuriousMind

@BernardoMeurer That's a horrible instruction :P

Lu Bu

17:45

@JohnathanRalls A fourth degree polynomial, i think.

Bernardo Meurer

@ACuriousMind I feel like pain today :P

ACuriousMind

@LuBu Of course you will. Polynomials are continuous and go to infinity as $x\to\pm\infty$, so they have to yield prime numbers.

Johnathan Ralls

@Lu

oops!

Bernardo Meurer

Must... resist... redefining... infinity

John Rennie

@LuBu: I guess you're thinking that if: $$ P(x)(x+1) = \text{a prime} $$ then because the left hand side is a product that means this can't be true.

Lu Bu

17:49

@JohnRennie Yeah.

John Rennie

But remember that a prime is prime because it can't be factored into integers, and neither $P(x)$ nor $x$ need be an integer.

Lu Bu

@JohnRennie Yeah, i prob asks these questions too hastily.

dmckee

@Secret Some comments on the shutting down of Bael's list. (A) That list was important. (B) It could have used some transparency. (C) An archive won't play the same role, because the frauds keep setting up new venues. (D) The list was never really complete or up to date because the frauds keep setting up new venues.

JamalS

@dmckee I presume the frauds bother doing this because there is some fee associated with making an application?

dmckee

I'd be willing to put some effort into a crowd-sourced system if it provided a transparent enough mechanism; perhaps scoring against a rubric.

Lu Bu

17:57

@JohnRennie So if the x is an integer, then it wont generate any primes, right.

dmckee

@JamalS Where they insert the moneymaking varies, but it many cases yes. There are also few that are uncritical mutual appreciation clubs: we all agree to "review" each other's work in a positive light and we can al get "published"!

John Rennie

@LuBu Not necessarily. e.g. you could have $1+x = 2$ and $P(x)=2.5$ to give the prime $5$.

Lu Bu

Oh.

Johnathan Ralls

got you with a two. ah snap

dmckee

@JohnRennie Last moth I listed to a reading of "Punk Voyager" on Escape Pod. You're old enough to really appreciate the genius of how the story captures the fractious nature of the punk subculture. It short and very funny.

John Rennie

18:01

@dmckee This?

I note there is a warning Rated 13+ for rebellious vulgarity :-)

dmckee

@JohnRennie That. Worse than the vulgarity it has Nancy Reagan.

John Rennie

@dmckee Two paragraphs in and I'm already laughing out loud :-)

Emilio Pisanty

hey @dmckee is this something I should flag? I really hesitate to respond to it, and it's not adding to the (already terrible) quesiton, but I'm not sure if immediate deletion is appropriate.

though actually, come to think of it, I'm unsure why that is still kicking around

Danu

I don't think your comment was particularly rude...

dmckee

@EmilioPisanty I'm just going to delete both to prevent unnecessary conflict if you don't object. I thought your comment was fine but could have been more tactful if you had wanted to put more time into it—something I try to do, but sometimes let slide.

Emilio Pisanty

18:14

@dmckee I don't object

it's a good idea, actually

thanks for intervening

dmckee

Mostly I think that Marty has a chip on his shoulder which is too bad, I think he could have some really interesting things to add, not only on Stack Exchange, but to the wider discussion.

If he was willing to frame them constructively.

Bernardo Meurer

Who's Marty?

Danu

Marty Green (find him on the main site)

John Rennie

@BernardoMeurer I have a vague recollection of being criticised by him for something, though I forget what. Being elitist I think.

Bernardo Meurer

@JohnRennie He criticised you? I like him.

Balarka Sen

18:28

@dmckee I think so too.

Bernardo Meurer

Marty Green, Canada

2.3k 1 8 17

quantum-mechanics electromagnetism photons homework-and-exercises electromagnetic-radiation electrons atomic-physics

This fella?

John Rennie

@BernardoMeurer clearly a man with good taste in physicists :-)

Danu

Hi Balarka

Balarka Sen

Yo

Sup

Danu

Does "applying spectral sequences to compute invariant cohomology" sound remotely doable for you?

Balarka Sen

18:30

I dunno what invariant cohomology is.

Spectral sequences are neat stuff

Danu

Me neither. It's a notion for homogeneous spaces so something having to do with group actions.

I want the cohomology ring of $G_2/U(2)$ for some embedded $U(2)$ subgroup

Bernardo Meurer

His blog seems cool

John Rennie

Someone just flagged the Shog :-)

Bernardo Meurer

Lol

Balarka Sen

@Danu sounds like something Mike can help you with

John Rennie

18:32

That's a great countdown animation for the room unfreezing ...

I wonder if we could a mod to freeze the h bar to see if we get the same animation?

Danu

@BalarkaSen I'm kinda hesitant asking Mike about stuff these days. He seems to be busy.

Bernardo Meurer

We had ACM freeze the h-bar before

That's when we made the j-bar

John Rennie

@dmckee if you freeze this room do we get a countdown animation like Literature?

Bernardo Meurer

I think it was just me and Ryan trolling too much, with obe and other people

@JohnRennie Yes

Balarka Sen

In any case I think you get a fiber bundle U(2) --> G2 --> G2/U(2) and you want to do a spec. seq. argument on that. I have no idea how how to do it other than mumbling about it though

@Danu I think he's spending more time playing Advance Wars than writing this week

Danu

18:35

In any case, my supervisor didn't mention spectral sequences; just Ted brought it up and I wondered if it'd be doable.

Balarka Sen

These are the kind of things that spectral sequences do, yeah

computing cohomology of a term in a fibration given the others, etc

Danu

Hmm.

For now I'm doing more down-to-earth, stupid things to compute it

I know Chern numbers and I'm trying to just get the Chern classes

so far I'm using prime factorizations haha

numerology

Balarka Sen

hrm. unfortunately I can't help you much with this

i think you just shoot Mike a message. if he's interested he'll give you a hint or two, if he can't do it he'll pass

Danu

I just need $c_2$ and $c_3$ and I'll be done :P

JamalS

@Danu Of what bundle?

I spent last month computing Chern classes for a variety of things

Danu

18:38

@JamalS Tangent bundle of $G_2/U(2)$ (there are multiple such manifolds---I need a particular one)

I'm doing the one that is the twistor space of $G_2/SO(4)$ (if that means anything to you... doesn't mean all too much to me yet)

JamalS

@Danu My understanding of $G_2/U(2)$ is as a Grassmannian manifold of 2-planes in $\mathrm{Im} \mathbb{O}$.

Danu

@JamalS Ah, tell me more about that

There are two $G_2/U(2)$'s which are both related-ish to Grassmannians

Tell me where to read about it

because so far I don't know any sources

JamalS

@Danu I read about it briefly en passant in a paper; I will review my browser history and find it

@Danu It is mentioned briefly here projecteuclid.org/euclid.kmj/1138043794

Danu

> The homogeneous manifold

But there are at least two (and they're not even homotopy equivalent)

Anyways, thanks

That's one calculational paper :P

JamalS

18:56

@Danu Is this an exercise?

Danu

@JamalS What?

JamalS

@Danu Finding the Chern classes for $G_2/U(2)$?

Danu

@JamalS It's the first part of my thesis

...so in a sense an exercise.

JamalS

@Danu Oh, what's your whole thesis about?

Danu

Computing characteristic classes of homogeneous spaces :P

(without Lie theory)

JamalS

19:00

@Danu Oh, haha, fair enough :) Well, I'm guessing you're looking at cohomological Serre sequences then?

Danu

No, no spectral sequences so far. Everything by complex geometry

It's already known how to compute them using Lie theory and my supervisor is interested in finding geometrical arguments to achieve the same results.

JamalS

@Danu Oh, out of curiosity can you direct me to a resource that computes them by Lie theory?

Danu

He's done it himself for the sequence $U(n+2)/U(1)\times U(1)\times U(n)$ already. Now I might do it for some other examples. At least that's what I'm doing for now.

Hirzebruch & Borel's famous 3-part paper

maths.ed.ac.uk/~aar/papers/bh1.pdf

First part ^

JamalS

Yeah, I just found it. Holy shit, it'll take me a long time to go through all 3.

Danu

He strongly discouraged me to try :P

JamalS

19:05

PS: Can anyone answer math.stackexchange.com/questions/2103017/… ?

DanielSank

Hi, everybody.

Danu

Hi Daniel

Slereah

19:22

Hi, doctor Nick!

David Z

19:53

@EmilioPisanty For future reference, the content of that comment is not something I would consider particularly flag-worthy. (Of course, something that old you can always flag as obsolete.)

Bernardo Meurer

@DavidZ If next week we had a groundbreaking discovery, that proved wrong some part of mainstream physical theory, say something weird proved particle-wave duality wrong, what would PSE do with all the outdated answers?

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