The h Bar

Sofia

01:29

@DanielSank Hi! What time is it in tour country that you don't sleep at this hour?

T Abraham

@Sofia u live in romania?

Sofia

@TAbraham No, I am from there.

T Abraham

@Sofia where do you live.. don't u sleep at this time?

Sofia

@TAbraham I should, well, it's almost morning. But You, are you from the western coast od USA? Only in that region people are not supposed to slip by this time.

T Abraham

01:52

@Sofia where do you live but?

I have a question, I know it may seem dumb...

Why does the Langrangian need to know the position function to figure out the dynamics of a particle when that's what the position function does?

Probably dumb.. I studied this so should probably know this...

Sofia

02:09

@TAbraham, it's better not to answer at this, I live in a region of great conflicts. For having freedom to speak with everybody it's better not to say where I am, and not to ask where people are from. What to do, the real world outside our beautiful and shining physics tower, is stupid and dark (in understatement).

hwlau

@ChrisWhite So you should go and get a job, don't be a graduate student ;)

BTW, open office space is bad.

Sofia

@TAbraham : to your physical question, what if we don't know the position function, only the potential energy and the expression of the kinetic energy?

@TAbraham : by the way, the Lagrangian is a good thing, it may tell you about different symmetries of the system, which simplifies a lot the task of finding the evolution of a system.

DanielSank

03:15

@Sofia I live in California.

T Abraham

04:02

@Sofia in what situations would this be the case?

ACuriousMind

Hmmm...math.SE just migrated this question to us that explicitly states that we don't want it, and is already closed here once

...and it has come with 4 upvotes.

T Abraham

@ACuriousMind actually three..and soon 2!

Kyle Kanos

04:21

@ACuriousMind Yeah, that probably should have been rejected. I think I might have to say something about that in the com-box

Kyle Kanos

04:40

Turns out it was closed there at Math.SE as off topic: math.stackexchange.com/posts/1107394/revisions

T Abraham

07:00

10

Nanoscience and Nanotechnology

Proposed Q&A site for students, professors, and researchers to ask questions about nano-science and nanotechnology

Currently in definition.

DanielSank

09:21

@Danu you around?

Danu

@DanielSank yush

DanielSank

09:45

@Danu Did I fix that radiation answer to your satisfaction?

Danu

Not really

I was looking for math :P

but you can just explain it here if you'd prefer that

DanielSank

@Danu Ah.

I don't think a full demonstration of Fermi's golden rule should be in that post :)

Are you familiar with Mr. Fermi?

Danu

oh golden rule okay

DanielSank

You're ok now?

Danu

never really used it, but I've seen it

DanielSank

09:51

If that was helpful then I should probably edit it into the answer.

Danu

too practical

(kidding)

DanielSank

wtf?

How is perturbation theory too practical?

Danu

...kidding

DanielSank

Hmph.

Danu

It is more practical because ideal systems usually don't require it ;)

...sorta by definition

DanielSank

09:53

One can never be sure with you.

Grump grump grump

Danu

You're just so easy to mess with

DanielSank

...grump...

Danu

btw

interesting question raised by a friend of mine

I'm considering posting it

DanielSank

@Danu I'm actually not sure what you mean by that.

Danu

Can we probe the essential spectrum of observables?

DanielSank

09:56

@Danu Huh?

Danu

@DanielSank If you idealize a system you remove all perturbations

DanielSank

@Danu Since when does "ideal" mean "solvable"?

Danu

Thats kinda the definition of idealizing it

@DanielSank you experimental troll you :D

DanielSank

@Danu Uh... ok. Usually "ideal" means "no friction" etc, but whatever.

Danu

@DanielSank That's one particular instance.

...the classic Newtonian one

DanielSank

09:58

@Danu Yeah, but a system without friction isn't necessarily solvable!

Danu

but obviously the term ideal should not just refer to friction

DanielSank

Like, three orbiting bodies is not solvable.

Danu

No, of course

DanielSank

Whatever.

@Danu ?

Danu

@DanielSank What's there to 'huh?' about?

I'm talking about the essential spectrum from functional analysis

DanielSank

09:59

@Danu Stupid experimentalist troll doesn't understand teh questionz.

@Danu Uh, oh.

Danu

Essential spectrum

In mathematics, the essential spectrum of a bounded operator is a certain subset of its spectrum, defined by a condition of the type that says, roughly speaking, "fails badly to be invertible". == The essential spectrum of self-adjoint operators == In formal terms, let X be a Hilbert space and let T be a bounded self-adjoint operator on X. === Definition === The essential spectrum of T, usually denoted σess(T), is the set of all complex numbers λ such that is not a Fredholm operator. Here, an operator is Fredholm if its range is closed and its kernel and cokernel are finite-dimensional...

DanielSank

I lack the vocabulary needed to parse your statement.

Danu

...strange, this wiki article talks of bounded operators but I'm pretty sure that's not a necessary restriction

DanielSank

Man, wikipedia...

So much horrible writing.

Danu

I like wikipedia

solid 8.5/10

DanielSank

10:01

The people who write these articles don't explain anything.

It's such a mess.

Danu

Meh, it's pretty good for math actually.

It's just not a first introduction to matters.

DanielSank

I am not a math n00b and I find Wikipedia mostly useless for math.

Every now and then you get lucky.

Danu

Then you're looking in the wrong places

DanielSank

Here's a great example of why I think Wikipedia falls short

Danu

just yesterday, I learned what a fiber bundle is; turns out I already knew about them but just didn't know the terminology. Now I can say all kinds of crazy-sounding stuff that's really quite basic :D

@DanielSank What's wrong with it? I'm not gonna read the whole thing

DanielSank

10:03

Nowhere in that entire article is there any mention of Polya vectors.

Danu

...because that's not mainstream.

Gowtham

whats that

DanielSank

@Danu I am so upset by this.

@Danu and that.

Danu

If you take a look at most complex analysis textbooks, do they mention it? I doubt it

DanielSank

(not really, btw)

@Danu And it's a damn shame.

You'd think an open resource would do better.

Danu

10:05

...but it makes your complaint obviously unreasonable.

DanielSank

@Danu False.

Danu

Edit it in then, you ass :P

DanielSank

@Danu I used to.

@Danu False because I think most textbooks fall short too :P

Danu

Either (1) Improve it, or (2) Stop complaining

:D

@DanielSank Then it's just you

►

DanielSank

@Danu That's funny given that I frequently get told that I'm really good at explaining things :)

Danu

10:06

@DanielSank What? That's irrelevant here.

It's just you in the sense that it's just you who thinks it falls short; it actually conforms to the standard. If you disagree with that, then well... do something about it! :P

DanielSank

@Gowtham Google it. You can understand complex number integrals as line integrals of a 2D vector field. It makes the Caucy integral formula obvious because poles of complex functions are understood as delta functions in the divergence of the vector field.

Danu

I'm sure your explanation based on Polya vectors is great (I'm still gonna read that little piece on it you sent me)

Gowtham

i am not a fan of complex analysis , but i have never heard of this ever before , like you say not in books or internet

DanielSank

@Gowtham It is completely ridiculous that this isn't taught in school. It relates two un-obviously related branches of mathematics in a simple way, makes the Caucy integral formula obvious, and allows you to visualize what's going on when you do contour integrals.

Why teachers don't teach it is a complete mystery.

Danu

@Gowtham but but but it's so nice!

complex analysis, that is

DanielSank

10:10

@Danu: The easy parts are nice :)

Danu

@DanielSank I just have to say that you're appealing to some kind of authority that you really don't possess.

DanielSank

@Danu Eh?

Who appealed to authority?

Danu

You

DanielSank

Oh?

Danu

1 min ago, by DanielSank

Why teachers don't teach it is a complete mystery.

...because you think it's so much better

DanielSank

10:11

How is that appeal to authority?

That's a statement of my opinion. I don't reference anyone else's opinion.

Danu

Hah

You for the "...to me"

Right now, it purports to be a factual statement

with "...to me" it is much more reasonable

DanielSank

Searched page for "to me". Your message is the only instance.

Danu

No that's what I mean

You should add "...to me" to that message

DanielSank

omg are you seriously complaining because I didn't explicitly say "to me" in my statement?

facepalm

Danu

Yeah! I took it the wrong way

DanielSank

10:13

You must be from the West Coast...

Danu

Amsterdam, actually

DanielSank

Where I grew up people throw their opinions around in casual debate all the time. It's expected.

Danu

@DanielSank I expect a slightly higher level of precision in written debates :)

DanielSank

@Danu Ok, have fun misunderstanding everyone :)

Danu

but okay, as long as "...to me" is implied that statement is fine

@DanielSank No need to suddenly be all angry and stuff

DanielSank

10:14

@Danu If I said "the nature of dark matter is a complete mystery" that would be a different story.

I think it was clear that I was stating my personal thoughts on the issue of complex analysis pedagogy.

@Danu Not angry.

Danu

Anyhow

cool

cause I think we get along great in general, so let's not spoil that

Gowtham

@Danu chill guys O.o

DanielSank

@Danu You keep putting :) symbols at the end of your aggressive statements. Don't pretend like I'm the only one doing it :)

Danu

@Gowtham We cool, yo

DanielSank

Everyone's cool.

Danu

10:16

@DanielSank ...but but but I didnt have any aggressive statements!

(also no smileys luls)

DanielSank

"I expect a slightly higher level of precision in written debates :)"

Check

Danu

Ahhh come on that's not aggressive

DanielSank

It could be construed that way. Maybe I should require you to be explicit about that in case I take it the wrong way :)

Danu

The implied message was "okay fiiine, but I maintain the right to claim being "technically" correct'

DanielSank

I'm teasing you now.

Danu

10:17

@DanielSank Lmao

DanielSank

How come you're allowed to use implied meaning but I'm not?

(more teasing)

Danu

Becuase I'm superior

theory and all

:D

TEASE

DanielSank

Yes. Quite.

This is another interesting cultural difference between East Coast USA and everywhere else I've ever been.

Danu

Nah man

I'm pretty accustomed to East Coast USA

DanielSank

I'm used to people strongly disagreeing with each other and ruthlessly tearing each other's arguments to pieces.

Danu

10:19

I've spent a lot of time there the past year

DanielSank

However, this is not personal. Everyone is friends in the end.

Danu

But that's exactly what we're doing, no?

DanielSank

In California, and in Europe AFAICT, this does not work.

People don't tolerate it.

Danu

Lol

you so wrong, brah

This works everywhere

DanielSank

Just telling you my experience.

People get really offended by this.

Danu

10:20

Just last night I did this with people from Europe, Latin America and Australia, all at one table

DanielSank

Aussies are great about this.

Danu

we were talking about whether humanity can ever know that we have "the final theory" (under the assumption it exists)

I maintain we cannot

DanielSank

I'm just telling you my experience. Obviously any generalization is never really correct.

However, this was a major difference I found in coming to the West Coast, and in working with international post-docs.

Danu

Okay, let me qualify my statement too

This works with physicists everywhere, as far as I know

Not so much with most others

DanielSank

@Danu Yes, but only if talking about physics.

Try a more personal issue and see what happens :)

Danu

10:22

Or maybe it's just me being a general rude asshole

@DanielSank Wrong, already did!

DanielSank

@Danu We can start a club.

Danu

I had a shouting discussion about my friend's terrible taste in music

(of course he thinks the same of mine :D)

DanielSank

@Danu Nice.

Dutch?

(the friend)

Danu

and whether music critics can ever be objective

@DanielSank Spanish

Also lololol chat is constantly preventing me from typing as fast as I would

DanielSank

Indeed.

Danu

10:23

really annoying

Gowtham

reg my hate to complex analysis , lets just say i sorta lost interest in math hugely during undergrad , i like numerical analysis very much tho ,

Danu

retry... retry... retry

DanielSank

@Gowtham Your lack of interest was probably due largely to horrible teaching (in my opinion, Danu).

Danu

@Gowtham Suuuuch a shame. Math is very beautiful. Maybe, as a physicist, you'd prefer geometry. Geometry and complex analysis go so well together too

Gowtham

@DanielSank +1

Danu

10:24

@DanielSank Incorrect usage! You already qualified it with a "probably"

DanielSank

@Gowtham I gave up my minor degree in math one course short of the degree because the teaching was so bad I couldn't stand it.

Danu

An F for written discourse!

Gowtham

and i am no physicist :P more of material science , metallurgy etcc

Danu

@DanielSank damn that's really rough

@Gowtham Ah... then maybe you just don't like math too much :P

DanielSank

So I taught myself the rest.

Danu

10:25

@DanielSank ...he said, patting himself on the back

DanielSank

@Danu Damn straight.

Danu

(teasing)

DanielSank

(not teasing)

Gowtham

i was pretty good at at it and slightly am , i just pursued a path very different , not much math in my subject

DanielSank

:)

Danu

10:26

This is great

DanielSank

@Gowtham Indeed not. Still, materials science is the unsung hero of the modern world.

Danu

@DanielSank Meanwhile, HEP is stealing all the singing shine

►

DanielSank

►

Danu

I love that one too

DanielSank

@Danu: Your move.

Gowtham

10:28

and here in India where schooling and undergrad is kind of nightmare , only a specific central govt. syllabubs (availability in schools very less) has good teachers , most of schools and colleges kinda force rote learning which is pathetic

DanielSank

@Gowtham That is not good.

Why is that?

Danu

@DanielSank First produce me a material science song!

DanielSank

@Danu They're too busy doing real work.

BAM!

Checkmate, bruh.

Danu

Meanwhile, nobody cares :)

Gowtham

Education here kinda has become a commodity , more sadness, private schools and state(different from central) are more interested in making money

DanielSank

10:31

@Danu says the clueless theorist typing away at his miracle of materials engineering

(was that too far?)

@Gowtham Are the private schools good?

Gowtham

only if they have two types of syllabus CBSE or ICSE

DanielSank

CBSE=?
ICSE=?

Google's not really helping me here.

Gowtham

central and international syllabus , they are very less compared to something called matriculation/state syallbus,

DanielSank

I apologize, I don't understand what you mean by "they are very less".

Danu

@DanielSank I'm tempted to make a yo momma joke now, we've come to that level :)

DanielSank

10:34

@Danu Do it!

►

Danu

HELP A moderator! Hide!

DanielSank

runs for cover

Gowtham

CBSE ICSE

@DanielSank i mean schools which have those syllabus are less compared to the state/matriculation type (rote learning) - due to politics in education system

DanielSank

You mean less in terms of number of schools?

Gowtham

yes

DanielSank

10:37

Ah. Now I understand.

@Gowtham: Well, all I can say is that I hope this changes for India.

Danu

Rote learning

Gowtham

well not in near future , the indian style(a central and state) of govt is major reason i think and corruption :/

Danu

how is that even still a thing at university

Gowtham

@Danu its a sad reality my country lives in

DanielSank

@Danu: Going back, it's kind of funny that you say I have to edit Wikipedia or stop complaining. I'm not sure it makes sense to disallow someone to voice their opinion of a thing unless they are willing to spend time changing that thing. For example, if someone says "I don't like eating shellfish" I don't say "shut up or fix shellfish".

Danu

10:42

@DanielSank That analogy fails trivially, for exactly the same reason that it sounds funny :P

DanielSank

@Danu Failed to parse argument. Content missing.

Danu

@DanielSank You are the real robot!

DanielSank

@Danu Robot? What are you going on about now?

Danu

"fix shellfish"

DanielSank

sigh

Danu

10:45

@DanielSank I was referencing a discussion from a few days ago due to, I think, Horvath's post about me being a sick individual and all of us being robots

See Jim's starred message about robots.

Gowtham

hahaha

DanielSank

fix Wikipedia.

Danu

one DOES simply edit an article. THat's the point.

DanielSank

I could spend hours trying to do that. In the past my edits have been eventually lost.

It's very discouraging.

Danu

Hmkay

Fair enough

DanielSank

10:47

It's not worth it IMO.

Danu

@DavidZ would you know whether there are any monographs on Yang-Mills theory that focus specifically on the mathematics (geometry)?

@DanielSank Fair enough

DanielSank

SE is better. The data model is much better.

Danu

It is

Damn, I chased him off with my question :P

DanielSank

@Danu So why spend free time editing Wikipedia!?!?

The weight of your previous statements and admonitions is evaporating as we type.

You must lower the vapor pressure.

Danu

There never was much weight to them

It was more of a fun intro to a discussion :)

DanielSank

10:49

facepalm

Danu

I argue for the sake or arguing; don't even pretend like you don't do the same

DanielSank

To quote a very wise individual: I expect a slightly higher level of precision in written debates :)

Danu

The statements were precise

DanielSank

Yeah, true.

Fine.

Danu

#rekt

:P

DanielSank

10:50

lololol

Danu

I should go do groceries

DanielSank

@Danu Never.

Danu

Are you into cooking at all?

DanielSank

@Danu Have you ever taken a look at my profile? Cooking is one of the things I bothered to mention :D

Danu

@DanielSank Not really

DanielSank

10:52

Anyway, yes, I'm into cooking. A lot.

Danu

That's great man, I'm really passionate about it too

DanielSank

What are you working on recently?

I went through a baklava phase but I'm happy with it now.

Danu

Meh, I'm not into sweets so much

DanielSank

I was on Indian food for a while. Coming back to Chinese recently.

Danu

I don't have time to do great cooking experiments a lot - I get home past 7 PM almost every day and have to study on the weekends too

DanielSank

10:53

Still working on baozi. I can't get the dough to rise properly and I think it's because I need a bigger steamer.

Danu

I counted this week: I'm at 52 hours over 5 days :\

DanielSank

@Danu woof

Danu

Will be around 65 this week I guess

not fun

DanielSank

I will talk food any time.

Any kind.

Danu

But I try to cook every day

mostly chinese-ish

DanielSank

10:54

Had fantastic pork and cabbage in Hawaii this weekend.

Danu

thats what I was raised on

DanielSank

I am very fond of Szechuan style.

Danu

My mother is a fantastic cook (and not in the way that most other people say that :P )

so I get my recipes/ideas frm her

DanielSank

I'm hungry now.

I want to go eat hot pot.

Danu

She's recently shifted, I think, to a more mediterranean style

DanielSank

10:56

Mediterranean is what I grew up on. Lebanese to be specific.

Danu

She also makes a lot of bread and pies/cakes

DanielSank

This is one of the most divine foods: foodnetwork.com/recipes/aarti-sequeira/…

Not that recipe necessarily, but the dish itself.

Danu

Today I was thinking of making fried spinach balls, and a bell pepper/potato soup

...or a lentil soup

DanielSank

@Danu You know, I never got into soups.

My SO is in charge of soups.

Danu

I am, but out of necessity

I look like average body type, but I'm always struggling not to gain a lot of weight

DanielSank

10:58

Exercise is quite useful for that.

Danu

My mental is just really out of sync with my body on what I need, foodwise :P

Sure, but watching your eating is much more efficient

DanielSank

@Danu I disagree, actually. You can maintain healthy weight by diet alone, but it's much easier if you get regular strenuous exercise.

I mean, I used to eat probably ~3000 Calories a day and I was fitter than I am now because I swam four days a week for two hours.

Danu

For me personally it is not. Right now I'm not doing any sports due to (1) being new in the city I couldn't find the sports clubs (2) time constraints; but my usual routine (past 5 years or so) would be sports 4-5 days a week

that really didn't do much at all for me

DanielSank

@Danu That's too bad. Sports are good for your brain too.

Danu

@DanielSank Next semester I'll start up again; I just missed the tennis training cycle etc when I arrived in Munich

DanielSank

11:01

I am significantly more productive on days when I exercise in the morning.

Danu

I never have time to exercise in the morning; uni starts at 8 or 10

(and no, I'm not gonna get up in time to exercise before 10 AM classes, I don't get a lot of sleep :P)

Gowtham

are you grad or undergrad ? @Danu

DanielSank

@Danu That is not healthy. I recommend lots of sleep.

Danu

@Gowtham Graduate

DanielSank

You will get more done and more out of your education if you put the pen down and go to sleep.

Danu

11:03

@DanielSank I can deal with very little sleep

It's really not an issue; but I'm not gonna cut off even more of my sleep time

DanielSank

@Danu Not enough to get up and exercise before 10am though...

Danu

I get ~6.5 hours a day

@DanielSank I could, but it's just not worth it

Getting up at ~6:45 is kinda miserable

DanielSank

@Danu It is very rare that someone operates at peak performance on that much.

Danu

@DanielSank Maybe it's in my genes: My dad gets about 4-5 a day

DanielSank

@Danu Good Lord!

Danu

11:04

and has been on that routine for decades; no problem

Gowtham

hm ok , i usually play soccer/football in weekends , pretty much my workout hehe. i used to play lots of cricket/table tennis in undergrad.

Danu

He plays tennis 2-3 hours a day, too

DanielSank

That is quite amazing.

I should go to sleep.

Ciao.

Danu

Yeah, I do admire my parents' discipline :P

Gowtham

ciao

Danu

11:05

kk cya

Wait, is it 6 AM over there? lol

It should be, if you're in Boston time :P

Gowtham

well , its 9 am i think lol , Cali

Danu

That'd be 3 AM

And you're lecturing me about healthy sleep schedules :) Nice one, @DanielSank

Anyhow, Ima go do my groceries

Gaurav

11:48

@Gowtham Table tennis ? wheee ! I used to be a state level player until i joined my undergrad course. Now I have no competition here.. ALL NERDS ! :/
BTW, which state are you native to ?

Gowtham

12:23

@Gaurav Tamilnadu

Gaurav

12:37

@Gowtham I stayed in Coimbatore for a few years until I finished my schooling. It's really nice weather throughout the state unless you belong to Chennai. Man. That place.

Gowtham

vellore,trichy,tirunelveli all equally hot , atleast chennai has a beach

Gaurav

Lol. You belong to Madras ?

Gowtham

no tirunelveli, my sister works in Kalpakkam which is pretty much madras

Gaurav

Ah, nice. I've heard they make a special kind of sweet over there. I can't remember the name :) About the education system you were talking about in your comments a few hours ago, don't you think that the present state of the education system is predominantly due to the irrational emphasis olaced on English ?

@Gowtham

Gowtham

@Gaurav i wasnt state player myself, played at district level, but small town small school , also parents discourage heavily , but in NIT i had lots of good players to play with . so it was fun, also i kinda coached(helped) my close friend into TT :D

alarge

12:54

@Gaurav @Gowtham How important is education in India, and what is its historical role? For example, many (East) Asian countries back in the day adopted the Chinese civil servant system and the ideals of Confucianism, which led to an emphasis on education, and perhaps in particular on rote learning. I suppose the ideals of Buddhism, too, are of self-improvement, which at least in some countries/instances have probably supported the Confucian world view.

Gowtham

@Gaurav yes and no i think, i think we can agree english is nearly turning into a global language? so learning english is alright, but we should really learn in mother(/state ?) tongue to be able to truly realize our potential , but it is very hard to implement i think

alarge

So I'm wondering if the Indian system of education has similar roots.

Gowtham

@alarge tbh i have very little knowledge of ancient/medieval history of education in India, but our current system is basically an adoption from the British which is degrading gradually ..

Gaurav

*placed on English
You see, that's another problem. In my case too, parents discouraged anything to do with sports. They saw it as a threat to my financial health in the future. In foreign countries, there is atleast some scope for a career in sports.
@Gowtham

Gowtham

History of Indian education is quite a read i suppose

Sofia

12:59

@TAbraham : notify me when you are on the net, and I will show you a situation that particularly pleased me, and which illustrates how useful may be to know the Lagrangian, how much it can simplify calculi.

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