The h Bar

0celouvsky

05:00

@DanielSank hi

John Rennie

@Kaumudi.H: morning :-)

user228700

This will all be over in one month, @0celouvsky.

John Rennie

Till next year :-)

0celouvsky

@Kaumudi.H until the next batch of you show up

user228700

@0celouvsky Erm, they're here already but you can hope that they stick to the JEE room :-P

0celouvsky

05:01

I don't remember this happening last year

Anonymous

@JohnRennie I'm too annoyed. Okay, I'll try to exercise self control then.

0celouvsky

@Kaumudi.H :|

John Rennie

The chat has got a lot more popular.

user228700

Yes, it has...

John Rennie

In a way these arguments are a sign of success.

0celouvsky

05:02

@JohnRennie and yet we've lost many good members

Chris, Obliv, Obe, Duffield

John Rennie

@0celouvsky people come and go, and it's tempting to view people leaving as a downhill slide

0celouvsky

there are probably more

John Rennie

Whether that's really true is debatable.

user228700

@0celouvsky Huh? Obe left again? :-| That's a bummer.

DanielSank

@0celouvsky $$\int_0 ^{f(x)} f(y) \, dy = f(x) \, . $$

0celouvsky

05:03

@Kaumudi.H He deleted his account

@DanielSank I don't believe that for general $f$

DanielSank

Solve for $f$.

0celouvsky

@DanielSank $f\equiv 0$

next question

user228700

@JohnR: How's the restraint on over-consumption of food going?

DanielSank

Find a non-constant $f$.

0celouvsky

:P

John Rennie

05:04

@Kaumudi.H Good! :-)

DanielSank

@Kaumudi.H Are we trying to lose weight?

user228700

Nice!

user228700

@DanielSank Nah, not me; JohnR is attempting not to eat everything he sees while at his Mum's over the Easter holidays.

John Rennie

@Kaumudi.H Yesterday I ate nothing but the main meal. And I plan to do the same today. On Easter day itself there may be some chocolate eggs eaten :-)

user228700

Cool :-)

John Rennie

05:06

The main meal being a fish pasta bake - very nice too!

0celouvsky

@DanielSank Is there one? My preliminary calculation suggests it must satisfy $f(f(x))=1$.

DanielSank

@0celouvsky I have no idea. I just made it up.

0celouvsky

@DanielSank $F(f(x))-F(0)=f(x)$. Take the derivative and divide by $f'(x)$ (assuming it's not zero), you get $f(f(x))=1$.

So...idk.

Slereah

@0celouvsky is that one of those fixed point thing

user228700

BTW, @BalarkaSen: I know that you have an inherent dislike for YouTube videos but I believe you might enjoy the videos of this channel:

user228700

05:10

youtube.com/channel/UCWTFGPpNQ0Ms6afXhaWDiRw/videos

0celouvsky

Why does balarka hate YT?

user228700

@0celouvsky I don't know if I'm correct about that but he does groan when I link to YouTube videos.

Anonymous

@Kaumudi.H Balarka himself links YT videos.

0celouvsky

^

user228700

But he also groans when I do the same sometimes :-P

0celouvsky

05:12

maybe he is groaning at your YT vids :P

user228700

Feb 17 at 11:31, by Balarka Sen

Articles available on internet definitely falls into the category I'd call "actual". I just don't like ideas which are communicated through videos in a flurry; I am not being derogatory towards analysis of stuff through youtube channels, I just don't like that sort of thing. A personal choice.

Anonymous

@Kaumudi.H He means educational videos I think

user228700

Obviously, yes.

Anonymous

On the other hand I find Youtube very useful. My teacher holds live physics sessions with us on Youtube.

user228700

@blue I'd have failed 12th std were it not for YouTube. I've learned a lot from many many channels; YouTube is baaaasially my life (:-P) and has shaped my life till now in significant ways.

Balarka Sen

05:14

did i miss anything?

Anonymous

@Kaumudi.H Same here :-)

Swapnil Das

PG, who can forget.

Anonymous

@SwapnilDas Exactly!

Balarka Sen

@Kaumudi.H Fair enough. What're the videos about?

user228700

@SwapnilDas Eh. Doc Schuster, WL, PatrickJMT, M-learning, R Shankar, the list goes on and on and on...

Yashas

05:17

@Kaumudi.H R Shankar? Yale?

user228700

> Now You See It explores film themes and tropes. It's like a college film analysis class minus the lecture halls, essay assignments, and student loan debts.

Anonymous

@Kaumudi.H Shankar, yes! His videos helped me a lot while learning waves

Yashas

MIT OCW is missing from your list! Walter Lewin!

user228700

@Yashas Yep.

Swapnil Das

Oh, the theoretical physicist.

Anonymous

05:18

Walter Lewin's videos are unclear

user228700

@Yashas WL=Walter Lewin :-)

Anonymous

Not good quality

Swapnil Das

Exactly^

Yashas

:|

Balarka Sen

@blue I frequently watch songs or uploaded movies or interviews of certain people I am interested in or talks, and youtube is a rich place to find those. I don't see a lot of analytical videos

Anonymous

05:18

MIT removed his videos

Balarka Sen

@Kaumudi.H Gotcha. I'll have a look, thanks.

Anonymous

@BalarkaSen I deduced that from the statement K linked.

Swapnil Das

Walter is mostly concerned for making you love physics, not learn physics.

Yashas

Anonymous

@Yashas How's the quality?

Yashas

05:19

I have WL's videos :D Downloaded them from iTunes before they were removed.

The video quality is low but the content quality is good.

Swapnil Das

Hey, hey, How could I forget Etoos? :P

0celouvsky

@BalarkaSen How would I show that for $F\in K(X)$, there a VB $E$ over $X$ and a trivial bundle $N$ such that $F=E-N$ in the Grothendieck ring $K(X)$?

user228700

I've found many of his lectures to be excellent, actually. He approaches the concept in the rawest possible way (which is why some of them are unclear, perhaps), which has helped me to develop intuition even for the most non-intuitive concepts.

Anonymous

@SwapnilDas Yesh! I bought the whole course

Anonymous

It helped me a lot

Swapnil Das

05:21

Even I am to.

user228700

Huh. I've never liked Etoos all that much. And this isn't taking away anything from the quality but geez, all the shouting! :-P

Balarka Sen

@0celouvsky I am honestly not familiar with $K(X)$, so I will just pass on :)

Yashas

Where do you get Etoos videos from?

I have seen some of them but they are sample videos.

Anonymous

@Yashas Buy them

Anonymous

From the website

user228700

05:23

I've only watched the ones available on YouTube.

Swapnil Das

Youtube has many

Slereah

Are there isometries that aren't the identity or a translation/rotation of some sort

or reflection

Yashas

@blue no $ to buy stuff; I use only the free stuff

Swapnil Das

@blue Sabne bola thik, maine bhi bola .. :P

Yashas

and I don't like JEE videos

Anonymous

05:23

@Yashas Ask papa

Anonymous

:-)

0celouvsky

The isometry group of the plane is $\Bbb R^2$ semi-direct product $\mathrm{SO}(2)$

Anonymous

They are really really good

0celouvsky

So, no for that one

Or do I mean $\mathrm{O}(2)$

Slereah

I mean for a general manifold

Anonymous

05:24

And the professors are from IISC and IITs

Swapnil Das

@blue IISc?

user228700

@Yashas Me neither. I've found that they skim over the concepts too fast and only focus on those parts of it that yield problems in JEE.

0celouvsky

@Slereah hyperbolic isometries are insane

Anonymous

@SwapnilDas Yes. One teacher is from IISC. I forget the name.

Yashas

@Kaumudi.H I focus on going beyond JEE so that I can hack in the exam.

Slereah

05:24

Let's investigate

Swapnil Das

AV sir?

@blue

Balarka Sen

Eg, inversion about circles

Anonymous

@SwapnilDas Maybe. Got to check.

0celouvsky

@Slereah ^

Slereah

Ah, there are dilations

user228700

05:25

@Yashas Oftentimes, their attitude is Samajh me nahi aya? No problem. Itna samajh ke problems kar sakte ho :-/

Yashas

@SwapnilDas @blue I think this discussion on JEE should be moved to JEE room before people get annoyed.

Anonymous

@Yashas Nothing more to discuss

Swapnil Das

Sure.

Yashas

@Kaumudi.H The goal of JEE courses is to make the student score as much as possible.

user228700

I know. It makes sense and all but it's annoying.

Yashas

05:26

I have seen Resonance's books; Their coordinate geometry has 123123123123 formulae. They don't even give the derivation.

They expect students to learn the formulae and use it in the exam.

Anonymous

@Yashas wtf

user228700

@Yashas Lol. I use Resonance, which is why I've had to hang around here so much to understand the derivations I think are important.

Anonymous

those are crappy books

Anonymous

i don't use any book

Yashas

Some students really learn it as it is and some students try to derive it themselves.

0celouvsky

05:27

@BalarkaSen I bet I'm not lucky enough that trivial $\oplus$ trivial is again trivial, am I?

user228700

@JohnR can attest to this fact :-P

0celouvsky

I don't trust the magical $\oplus$

user228700

Aaanyhoo...

Balarka Sen

@0celo Huh? Of course.

John Rennie

@Kaumudi.H :-)

Balarka Sen

05:32

@Kaumudi I watched their societal fears on film vid. It's not bad I suppose.

0celouvsky

@BalarkaSen I just can't wrap my head around the algebra. I can't go from $F\oplus E=X\times\Bbb C^N$ in $\mathrm{Vect}(X)$ to $F=E-N$ in $K(X)$

The notation is $N$ for $X\times\Bbb C^N$

Balarka Sen

I find that most analysis of the horror genre oversimplifies it somehow. Not unanticipated, given that it has became quite tedious with raw slasher/gore-fests once again after the pre-80's campy monster movies.

@0celouvsky Remind me what $K(X)$ is?

user228700

I really can't comment because I don't even watch movies. I watched their video on Opening Shots and liked the way in which it was analysed but couldn't add to the conversation because like I said, I don't watch movies that often.

Balarka Sen

Is this "vector bundles upto stable equivalence"?

In which case it's trivial.

0celouvsky

@BalarkaSen That's the idea, I'm working on the proof of that.

Slereah

05:36

Hm

If I do a book with everything about CTCs

I guess I have to talk about Ronald Mallett

Without being rude

Balarka Sen

@Kaumudi That's fair. I of course advocate watching good movies, but... tastes vary. :)

0celouvsky

The actual definition is $K(X)=\mathrm{Vect}(X)\times\mathrm{Vect}(X)/\sim$ where $(F_1,F_2)\sim (F_1',F_2')\implies (F_1\oplus G,F_2\oplus G)=(F_1'\oplus G',F_2\oplus G')$ for some $G,G'\in\mathrm{Vect}(X)$.

user228700

@BalarkaSen I'd like to watch good movies but my feed is cluttered with crap movies from the cinema industries in my immediate surroundings; Bollywood, Kollywood, Mollywood etc.

Slereah

Oh god

Ronald Mallett has some autobiography

Balarka Sen

lol

Slereah

05:39

blackhistory.psu.edu/assets/timeline/RonaldMallett_script.pdf

tough luck for black history that their GR dude is Ronald Mallett

Balarka Sen

well depending on what you want to watch i can recommend something but i can't guarantee that'd be interesting to you. i watch weird things.

you should also probably study for jee. sorry :P

user228700

@BalarkaSen I've noticed :-P

0celouvsky

@Slereah what?

user228700

Lol, I'll ask about it again after JEE.

Slereah

He's not the GR fellow with the best reputation

Balarka Sen

05:44

sounds like a plan

0celouvsky

@Kaumudi.H After JEE you are learning measure theory

user228700

@0celouvsky After JEE, I am sleeping for 10 days straight, that's what I'm doing.

0celouvsky

that's not healthy

we will assume you died

and have a funeral

user228700

x'D

Slereah

$\dagger$ RIP $\dagger$

0celouvsky

05:46

wtf am I even trying to prove

it's pretty late

Balarka Sen

you're trying to prove that you don't exist

K-theory is the only way to do it

Slereah

$\neg \exists @0celouvsky $

that reminds me of that crazy vixra paper

vixra.org/abs/1602.0010

0celouvsky

@BalarkaSen so you're saying trivial + trivial is trivial?

It makes sense

Slereah

Some papers on vixra aren't obviously crazy

0celouvsky

The proof should be trivial

Slereah

05:50

This one?

Totally obviously crazy

Balarka Sen

@0celouvsky it is.

Slereah

He literally proves the value of Avogadro's number in his theory

0celouvsky

lol

Slereah

Definition 1. $\circ$ denotes origin of truth. Define $\circ$ as all the most complete everything.

Balarka Sen

"nothing is telling something about everything"

0celouvsky

05:52

I just proved every bundle is trivial.

Can I haz Fields?

Slereah

Definition 2. $\theta$ denotes an alaya. Dividing $\circ$ by dimensions, the total contents of every $\aleph_1$ dimensions of $\circ$ can form an alaya $\theta$. The nature of $\theta$ is the great mirror wisdom, the wisdom has ability to map contents into their mirror images

0celouvsky

sounds like Hinduism

Slereah

yeah I think it's rooted in some crazy religious thing

Definition 60. According to Buddhist world view, Sumeru Mountain and Saline sea are on the earth wheel, the water wheel is under the earth wheel, the wind wheel is under the wind wheel. Jambudvipa located on the Saline sea in the south of Sumeru Mountain. Human beings are the people living on Jambudvipa. Define this kind of world as small world.

Balarka Sen

proof by Hinduism?

0celouvsky

I'm retarded

$F\in K(X)$ is a pair $(F_1,F_2)$ mod the equivalence relation. Let $G$ be a bundle such that $F_2\oplus G=N$ is trivial. Then...nope, still wrong

Argh

well, I think this still works

Then $(F_1\oplus G,F_2\oplus G)=(E,N)$ if we define $E=F_1\oplus G$

Slereah

05:58

Not knowing fiber bundle theory is the first sign of mental retardation

2

0celouvsky

so then that's in the equivalence class

@BalarkaSen Is $\oplus$ associative?

Balarka Sen

yes

'cause it's associative fiberwise...

0celouvsky

indeed

0celouvsky

06:26

I just wasted 30 minutes of my life

The proof was Trivial all along

@BalarkaSen Ok now I proved that $[E]=[F]$ in $K(X)$ iff $E\oplus N=F\oplus N$ for some $N$.

Balarka Sen

oki

0celouvsky

So...stable isomorphism

Is that what that's called?

Balarka Sen

ya

N is a trivial bundle, I hope.

0celouvsky

Yes, $N:=X\times \Bbb C^N$

Time to sleep

cheerio

Slereah

heh

Reichenbach has some wormhole-like space sort of experiment

Series of concentric shell

First shell is measured

The experimenter goes to the second shell

The second shell is smaller than the first shell

He deduces that the first shell contains the second shell

He then goes down to the third shell

It is the same size as the first

DUN DUN DUUUN

That's the classic Morris Thorne wormhole

although I think it's supposed to be a 3-torus of some kind

Balarka Sen

06:38

is wormhole even a thing

Slereah

define "a thing"

Balarka Sen

i hear it's consistent with GR. is there any evidence in real life?

Slereah

No

Balarka Sen

boo

Slereah

Wormholes require weird topology, and so far as we can tell, the topology of space is just $\Bbb R^3$

Anonymous

06:39

I don't know even if black holes have any evidence in real life

Anonymous

Does it?

Slereah

Black holes have some evidence

Anonymous

@Slereah Like?

Slereah

Depending what you mean by "black hole"

Anonymous

@Slereah The same as Wikipedia definition

Slereah

06:40

Well there are regions that have matter behaving exactly as it would around a black hole

Balarka Sen

spurts of electromagnetic radiation out of nowhere, or something like that iirc. i dunno

Slereah

Yeah, jets, X ray emission, gravitational lensing, redshifting

all that stuff

and no star in the middle

Anonymous

@Slereah Can you name the constellation or galaxy nearby any known black hole ?

Anonymous

Or any links?

Slereah

The most famous black hole is the one at the core of the galaxy

So it would be located within the milky way, sky-wise

I don't know the location of any other

Anonymous

06:42

Supermassive black hole

A supermassive black hole (SMBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses (M☉), and is found in the centre of almost all currently known massive galaxies. In the case of the Milky Way, the SMBH corresponds with the location of Sagittarius A*. == Description == Supermassive black holes have properties that distinguish them from lower-mass classifications. First, the average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water...

Anonymous

This ^ ?

Anonymous

Sagittarius A*

Sagittarius A* (pronounced "Sagittarius A-star", standard abbreviation Sgr A*) is a bright and very compact astronomical radio source at the center of the Milky Way, near the border of the constellations Sagittarius and Scorpius. It is part of a larger astronomical feature known as Sagittarius A. Sagittarius A* is thought to be the location of a supermassive black hole, like those that are now generally accepted to be at the centers of most spiral and elliptical galaxies. Observations of the star S2 in orbit around Sagittarius A* have been used to show the presence of, and produce data about, the...

Anonymous

Ah, I love astronomy :-)

Slereah

There has been some wormhole detection experiments but so far none of them found any

Not too surprising

Even if wormholes were around, they are generically unstable

any wormhole would just collapse to a mostly undetectable size

Balarka Sen

how can it be unstable? isn't the topology of the spacetime not going any undergoing change?

Slereah

06:43

By "unstable", I mean that the size of the throat collapses

Balarka Sen

so, like, the metric near it changes?

Slereah

under some analysis they might be stable when they reach about Planck size, but that's not v. detectable

The heuristic argument isn't too hard to see

Balarka Sen

cool stuff.

Slereah

Wormholes take converging geodesics and turn them into diverging geodesics

Just imagine radial curves going in the wormhole

In the optical approximation to GR, that behaviour is associated with negative energy densities

Balarka Sen

yeah that makes sense

Anonymous

06:46

Anonymous

Is this what theory predicts as the shape of wormholes ? ^

John Rennie

@blue that's a highly misleding picture.

Slereah

IIRC without negative energy wormhole throats collapse exponentially with time

Anonymous

@JohnRennie I doubted so...

Anonymous

Any better picture?

John Rennie

06:47

It shows a Morris-Thorne wormhole, but GR tells us nothing about what parts of the apcetime are linked.

Slereah

there's a paper that has actual wormhole behaviour simulated

John Rennie

@blue I've answered questions on this several times. Leet me do a quick search ...

Anonymous

@Slereah Can you link that paper? (I won't understand the maths though...)

Anonymous

I find this topic very interesting

Balarka Sen

watch Interstellar, you'll know everything about wormholes

Slereah

06:48

aapt.scitation.org/doi/abs/10.1119/1.1758220

John Rennie

4

A: Do wormholes only allow FTL travel in "folded" spacetime?

There is nothing in physics that describes the sort of folding shown in your picture. I'm afraid it is an invention of the Science-Fiction community. The best tool we currently have for describing spacetime is general relativity, but GR does not and cannot tell us anything about the global topol...

Slereah

Interstellar is pretty terrible for wormholes

John Rennie

3

A: How would you connect a destination to a wormhole from your starting point to travel through it?

When you are thinking about wormholes you are probably picturing something like this: The problem is that the best theory of gravity we have, general relativity, can only tell us about half of this image. General relativity is a local theory that relates the local curvature of spacetime to th...

Anonymous

@BalarkaSen Really? I've heard many people saying it is not accurate.

Slereah

Rendering a pocket wormhole using raytracing

►

Here's an example of a wormhole raytracer

Balarka Sen

06:49

@blue of course it's not, it's a movie

Anonymous

@JohnRennie Thanks...will read through :-)

Balarka Sen

from the hollywood

Slereah

For the basic Morris Thorne wormhole

John Rennie

4

A: Are wormholes really a valid shortcut to distant points in the universe?

Before we get into the issue of travel time we need to point out the science fiction idea of wormholes is rather different to general relativity. There are several kinds of wormhole metrics known in GR, but they just connect two asymptotically flat regions of spacetime. If we use a rubber sheet m...

Anonymous

@Slereah Thanks!

John Rennie

06:49

That's probably the most complete answer - start there.

Slereah

For the simplest Morris Thorne wormhole (the Ellis Bronnikov wormhole), you basically see two regions

one of them is like a deformed mirror

It's the ring you see

The interior region is the other size of the wormhole

Although it is usually a bit more complicated

Several rings might be involved

Also red/blue shifting

aapt.scitation.org/doi/suppl/10.1119/1.1758220/suppl_file/…

if we assume any old topology for the spatial section of the universe then there might be wormholes, but they might not be detectable

Due to the topological censorship theorem

so basically they are useless

John Rennie

Remember the magnet falling through a copper tube experiment. Well someone has managed to do it with a superconducting tube.

Now that's a cool (literally :-) experiment.

An excellent use of the physicists time and the research council's money :-)

Slereah

how accurate is the description of superconductors, anyway

People always brag about how they have 0 resistance but that seems like an approximation

For a start a current going round it would lose energy by Brehmstrallung

if nothing else

John Rennie

07:05

A superconductor works because an energy gap opens up between the ground state and first excited state of the Cooper pairs. As long as this gap is much greater than kT the pairs cannot be scattered.

But there must be some thermal excitation through the gap even if it's very improbable.

So I don't think a superconductor can have exactly zero resistance, though the resistance can be immeasurably small.

Slereah

heheh

Reichenbach's thought experiments with a 3-torus involves the covering space

Physics Meta

0

Q: Ways of promoting questions on PhysicsStackExchange

Is there way of promoting our questions to seek attention without bounties. I have seen people changing titles,keeping weird and strange titles("The Dark Black Holes "),sometimes even challenging titles("Solve it if you can") and these titles really get a lot of attention. But these are against P...

Slereah

The experiments involving spatial geometry for Reichenbachs involve the geometry of the world itself, the forces acting upon measuring apparatus, and the "causal anomaly" you would get from such things as the torus space

Where everything is repeated

so that you may still use euclidian geometry for any weird manifold, but only at a terrible awkward price!

Basically using the Pauli-Fierz description of the gravitational field and going to the covering space of the manifold

I'd send him an email to tell him about this but he's been dead for 60 years

it would be awkward

though so far he has not explained how to save euclidian geometry from the appearance of singularities

Since this is a 50's book I'm not sure that was a concern back then

Anonymous

07:53

@Yashas Ah...the insect is gone? =D

Anonymous

Back to the pink avatar =P

Anonymous

I actually liked it

Slereah

09:34

"In order to exclude such a contradiction, we must make the assumption that there are no closed causal chains."

Reichenbach does not approve of CTCs

user228700

10:27

@JohnR: Biriyani & potato chips for lunch today! :-)

Anonymous

@Slereah Why isn't the pdf opening ? I clicked on the blue button and the link given therein. It is going back to the same page.

Anonymous

I clicked on that blue link ^

Anonymous

And the "pdf" on the left

Anonymous

Doesn't work!

Anonymous

10:31

Do I have to buy it or something?

Anonymous

@JohnRennie I read through both of your answers. They are interesting. But I am looking for a more rigorous article that covers the reasoning as to why wormholes are actually supposed to work and the science behind it. Do you know any such web resource for beginners ?

Anonymous

@JohnRennie Do I have to start with general relativity ?

Qmechanic

5

Q: Is there a Virasoro group?

On page 14 of the survey article Kac-Moody and Virasoro algebras in relation to quantum physics by Goddard and Olive, the authors show that smooth selfmaps of the circle form a Lie group corresponding to the Virasoro algebra. I didn't fully follow their argument, and then I became more confused ...

mathematical-physics group-theory conformal-field-theory lie-algebra

Temporarily locked question to avoid migration cf. meta discussion about on-topicness of math questions. Input to how we proceed in this question is welcomed. ...[June 15th, 2017: Unlocked.]

Slereah

@blue yes

Anonymous

10:53

@Slereah Why is the paper not opening?

Slereah

because you have to buy it

(or pirate it)

Anonymous

@Slereah You should have said that earlier =P

Anonymous

Anyhow, I don't think I can buy it at present...

Slereah

sci-hub.io

hint hint

wink wink

nudge nudge

Taps nose knowingly

Anonymous

@Slereah aaahhhhhhhhhh

Anonymous

10:58

it works

Anonymous

wtf

Anonymous

that's called piracy...but I'm ok with it =D

Anonymous

lol

Anonymous

I'm thinking of starting learning GR from this channel

John Rennie

11:17

@Kaumudi.H Biriyani is nice - whether it's the same as pilau or not!

Fawad

@JohnRennie you cannot compare Biryani with pulao,Biryani has its own taste.

John Rennie

@Fawad I'm not knowledgable enough about Indian cooking to comment, but there seems to be disagreement about this point.

ACuriousMind

@Qmechanic I like the question, and I think that the Virasoro algebra is sufficiently "physics" that it should be on-topic here. The question itself can be phrased as a pure math question but the specific case of the Virasoro algebra is so inextricably linked to conformal field theory that we should not migrate it.

John Rennie

I suspect part of the problem is that the terms biryani and pilau are not strictly defined, so differegnt people mean different things by them.

Fawad

11:32

@JohnRennie sorry,I never tasted pilau,only Biryani...Sorry..

Anonymous

@Fawad pilau=pulao....you really never had pulao?

Fawad

@blue yes,never (・へ・)

Anonymous

@Fawad But it is made in almost all wedding ceremonies, isn't it?

Anonymous

Okay, nevermind.

Anonymous

I recommend it though. It is a nice dish.

Slereah

11:51

"Let us imagine that numerous mass points are whirling about at random in empty space. On each of these points there is an observer and these observers can communicate with each other by signals. With the aid of these signals they now want to establish a space-time order"

What a charming picture

ACuriousMind

@Slereah As long as they don't name it The First Order...

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