The h Bar

NEVER SAY HOWDY TO HIM

Er...?

user54412

12:49 AM

The last person to say howdy to me ...

...yeah...?

.-.

poor Kyle

poor, poor Kyle

._.

HE WAS SO YOUNG

well, like 31, but compared to really old people he was young

k...?

12:53 AM

he doesn't come around here anymore

Oh XD

@0celo7 Say, what'd ya major in for college?

gender studies

Oh...thought it'd be related to QM or something.

wow, prejudicial much

Er, no, just expected most people on this site to have majored in physics of some sort

12:58 AM

so you "expect" me to fit to your standards

I bet you think I'm male as well

...I did?

user54412

...

No wait, not because of anything like that

Just because you got a guy as your profile pic, so I...I...

uh-huh

.-.

12:59 AM

right

::wonders if CW is going to say anything::

user54412

0celo7s are male; 0cele77es are female.

Er...k?

user54412

@obe How often do you change your picture? And how often do you change the colorscheme?

So what're ya majoring in, Chris (if you're in college)

@ChrisWhite I normally don't change it... though I changed it a lot in the last 3 weeks. The color scheme is always blue.

1:01 AM

he's supply chain management

user54412

wait, I just realized some people have bio information that pops up when you click their name in chat

user54412

@Pies Do I seem that young? ;)

Dunno, I'm still in high school so...

I guess I'm "that young" ._.

user54412

my profile contains my life story, all 3 sentences of it

(mine too!)

why did you spoil it for him

1:06 AM

Funny, I wanna major in astrophysics...and I'm looking at princeton

I was waiting for him to find out on his own

sigh

has astrophysics increased GDP?

sigh...

user54412

@0celo7 who exactly do you think came up with this whole "fusion power" idea?

@ChrisWhite Donald J. Trump

user54412

exactly. astrophysicist

1:09 AM

in other news

@obe teach @Pies calculus

._.

he can learn it on his own in like 3 days.

he refuses for some reason

Sigh...a'right, how old were ya both when you learned calc?

15

1:11 AM

Wait how?

In sophomore year?

yes

you just learn it...

In school?

college

I meant sophomore year in high school?

the answer won't change

1:13 AM

So...ya learned it on you're own?

@Pies same as 0celo7.

mit has some nice lectures.

;-;

I watched them in 3 days on 3x speed.

and learned it... i guess.

user54412

I wish I could say I learned it at a normal age. But I was also around 15...

Sigh...so I gotta do something about this on my own?

Doesn't help that I skipped precalc

user54412

1:15 AM

@Pies Either you have a teacher, or you have to do it on your own.

probably the worst decision of your life

welcome to digging ditches

user54412

::wonders what precalc is::

Wasn't a decision. I did too good on my regent

@ChrisWhite 1+3=4

stuff like that

They just skipped me.

user54412

1:16 AM

regents? are those anywhere outside NY?

Nope.

Well, now I don't know calc or precalc. So trying to learn calc without any basic knowledge is unlikely

what do you think is in precalc

I dunno, differentials, integrals maybe

solve $ax^2+bx+c=0$

@Pies what the heck is in calculus then

Same thing, but more elaborate?

1:19 AM

no

can you solve that equation

er...does that problem need calc?

...oh boy

Since ya ain't giving me any of the variables...

Goddammit...

oh boy

...Did I fail?

1:20 AM

you failed Freshman math at my high school

.-.

I guess A = 0, B = 0, C = 0

oh god

@ChrisWhite @obe say something

;-;

idk what to say.

user54412

@Pies In all honesty, most people in the US who do take calc in HS retake it in college anyway. So you'll get it eventually.

1:22 AM

can you solve it

maybe that equation can't be solved

...what?

lol.

Ya didn't give me A, B or C. So I can't do anything with that...right?

holy crap

have you done any algebra

Of course

1:23 AM

@pies you didn't learn how to solve a quadratic equation?

we learned that in grade 7.

Oh crap

@ChrisWhite is this unreasonable for a junior to solve?

wait, I know it

Dammit...what's the quadratic formula again?

DERIVE IT

DON'T MEMORIZE ANYTHING

you can turn that into the quadratic formula by altering it a bit.

since he gave you the general form.

user54412

1:24 AM

@0celo7 Well, it was in grade 8/9 in my school.

-b ± √b^2-4ac
-----------------
2a

right?

wrong

you didn't derive it

0 credit

.-.

F---- for cheating

would you know how to solve it if he used variables s,d,f in the equation?

1:25 AM

Sigh...I shouldn't be forgetting basic algebra

Of course

you did get it right

but you either looked it up

or tried to remember it

I swear I didn't

I had to sing the song in my head...

you should have derived it

SONG

._.

lol it was once an exam equation to derive it in grade 10.

1:26 AM

they should make a song for remembering cohomologies...

@0celo7 I'm undepressed now, I can do the problem set.

To my defense...my algebra II teacher sucked. So maybe it's not entirely my fault...I hope?

...due tomorrow.

I walk into class one day and the question on the board is "If you are going 80mph, how many hours would it take you to go 80 miles?"

I swear I wish I were joking.

80?

dunno

1:28 AM

lol.

Yeah, but one of the morons in the class yelled "5.4, I CHECKED IT ON MY CALCULATOR"

user54412

how many of you remember the other quadratic equation to use when the standard one is prone to catastrophic cancellation? :p

Er...

what?

never seen a different one

@ChrisWhite never happened before.

1:29 AM

A'right, 0celo, ready for a math problem?

uh

as long as it's interesting

A pen and a notebook together cost $1.10. The notebook costs $1 more than the pen. How much does the pen cost?

wtf

.05

n00b

Dammit...

that's literally the topic of my psychology seminar...

1:31 AM

A'right, is it sad I don't remember long division?

yes

really sad because you need it in calculus.

to do those damn integrals.

I usually just figure it out in my head...

Sigh...

though not as sad as i didn't finish my qft problem set due almost 3 weeks ago.

dude

I SOLVED IT LIKE THREE TIMES WHILE PLAYING VIDEO GAMES

1:32 AM

So...now calc is kind of scaring me

@0celo7 show off.

that has nothing to do with it

Meh, I'll manage

I gave you the answers!

i need to write them down.

I was depressed ok.

1:33 AM

the professor was right about you

Er...ya okay, obe?

that's not an excuse

user54412

So you have $x^2 + a_1 x + a_0 = 0$. Define $s = \sqrt{a_1^2-4a_0}$. If $a_1$ is positive, your two (ordered) roots are best given by $(-a_1-s)/2$ and $-2a_0/(a_1+s)$. If $a_1$ is negative, the (ordered) roots are $-2a_0/(a_1-s)$ and $(-a_1+s)/2$. That is, the other formula is $x = 2c/(-b \pm \sqrt{b^2-4ac})$.

@0celo7 You don't know how it feels.

When in God's name did ya use that, Chris?

1:34 AM

wait why do I need that @ChrisWhite

@obe neither do your professors, employers or whoever needs or pays you

user54412

@0celo7 because using the wrong formula can lead to huge numerical errors

@ChrisWhite example pls

"wrong formula"?

Ya mean the other QF?

as long as $a\ne0$ I don't see any reason why it should not work

Say...does anyone here know some nuclear physics?

1:37 AM

0celo7 does.

user54412

Make $b$ large and positive. Then $-b + \sqrt{b^2-4ac}$ is close to $0$, but you're using up multiple significant figures keeping track of $b$.

no?

not yet

D:

@ChrisWhite you learned that in high school?

or some numerical class

user54412

@0celo7 No, which is kinda sad.

user54412

1:39 AM

But I guess kids would get all confused with two formulas running around.

well why would any of us know it then

cool i learned a new formula.

just do the problem set...

i will now.

So is there any redeeming quality of degrees?

Since they're just gonna get replaced with the more useful radians?

1:41 AM

@Pies most well paying jobs require one

...

user54412

"This line has a pi/4-radian slope." <-- said no one ever

Well yeah, but radians are more applicable than degrees

wow

angleist

.-.

But come on, 360° is just an arbitrary number. 2π at least makes sense

A circle could be considered 473° and it'd still be the same thing

1:43 AM

360 can be divided by like everything

Yes, but radians are absolute

Show this man some rational trig

There's a specific amount of radians that make up a circle. That won't change. But you could keep redefining the amount of degrees that make a circle.

Hell, degrees don't always work. Ya can't find Sin(x) using degrees, unless you convert them to radians first

Same with cosine

I don't agree.

@ChrisWhite why yellow

1:50 AM

Sigh...someday, maybe they'll stop teaching degrees altogether and just teach gradeschoolers radians

I doubt it.

no

what is wrong with you

me or him?

him

Why?

1:55 AM

degrees are going nowhere

just...just go learn calculus

you're wasting time on here

but...but...

you could have already learned how to integrate

sigh...

I haven't learned precalc. How do I go straight to calc?

I'd understand in school, since they'd recap the precalc. But online?

All right, imma go. 'Night

@obe teach him

I'm busy

teach him what?

@Pies I know exactly what you need.

2:04 AM

start with Zee and work up to Arnold/HE

I found this nooby calculus book I used when I was 15, it had a great chapter recapping pre-calc. It's called calculus early transcendentals by stewart.

@Pies read chapter 1 of it, find a pdf.

...he left.

it's snowing this week and -3.

woo.

I used Larson

Good book, had some proofs

epsilon-delta?

2:45 AM

yes

same... surprisingly those books had it.

Surprisingly you're not doing work

Q: Tiering tags according to user reputation in area

3:06 AM

by now it shouldn't be a surprise... idk why.

Shing

3:27 AM

I was playing Manipulate in mathematica 10

but it takes forever to see the result.

does that mean I should get a new computer? or something wrong in the Manipulate?

Shing

3:47 AM

for calculus, A.)pick any pre-calculur, then calculus you think you understand (at your level, I think the U.S. has many good pre calculus books, and calculus.), then read it, work the problem set. then you should B.) pick Apostol or Courant's Calculus. If you don't feel the awe of Apostol, Courant then you should probably return to A.) @Pies

DanielSank

7:50 AM

New close reason: "Post contains the phrase 'thanks in advance'."

@ChrisWhite heheh, true.

Physics Meta

8:54 AM

0

tl;dr: Tags for questions are unlocked with reputation, whereby you can have x levels of a tag (e.g. electromagnetism 1..5). Users can request a question to be tagged on a higher level if they don't have the reputation to do so themselves. Reputation gain could be higher for higher level question...

Q: Nonlinear dynamics beneath quantum mechanics?

10:13 AM

What happens when you search "Why quantum mechanics is linear":

6

Yesterday I asked whether the Schroedinger Equation could possibly be nonlinear, after reviewing the answers and material given to me in that thread I feel like my question were adequately answered. However could there still be nonlinear dynamics underneath quantum mechanics that could potential...

quantum-mechanics schroedinger-equation

10:31 AM

@Secret A more appropriate question would be, why there are nonlinear theories? :-P

you suggesting nonlinearity is an emergent property from linearity?

(At least that's the first thing I came into mind when I read your question...)

My mind must be short circuiting after that broad discussion with a peer that spans from science to arts to philosophy..

@Secret That's exactly what I was suggesting

interesting

and that is what actually happens

it is rigorously proved in many instances

Q: Linearity of quantum mechanics and nonlinearity of macroscopic physics

17

We live in a world where almost all macroscopic physical phenomena are non-linear, while the description of microscopic phenomena is based on quantum mechanics which is linear by definition. What are the physics points of connection between the two descriptions?

quantum-mechanics hilbert-space superposition linear-systems

10:38 AM

quantum mechanics is linear because we observe it to be that way

ans 1 mentioned a "mechanism" on how this occur

that "mechanism" is, nowadays, quite well understood

it's called classical/mean field limit

and it is, in my opinion, one of the few physical instances of something that is better understood by the mathematical community rather than by the physical one

Q: Logistic map chaos theory experiment, need advice on interpretation of results

The concept of emergence does reminds me of something I have done a week ago when I am self studying numerical analysis (give me a sec.. when I dig out the findings...)

1

Recently while studying this lecture notes to learn about numerical techniques, I performed the following experiment in Mathematica as the lecture note encourage the reader to explore the logistic map (which caused me to first learn and stumble upon chaos theory in the process, hence I am still r...

dynamical-systems chaos-theory

From that self study I learnt that chaos is deterministic, thus there is no randomness

and this caused me to have an hypothesis (after got my brain saturated with fourier series because of some quantum assignment or something)

Hypothesis:
Given some f that is closed under iteration:
$$f(r_{Chaos})=ar+bf(r_{Chaos})+cf(f(r_{Chaos}))+df(f(f(r_{Chaos})))+\cdots$$

Now I just need to prove this, or find a counterexample to it

sorry correction:
Given some f that is closed under iteration:
$$f(r_{Chaos})=\left. ar+bf(r)+cf(f(r))+df(f(f(r)))+\cdots\right|_{r=r_{Chaos}}$$

Now I just need to prove this, or find a counterexample to it

where $r_{Chaos}$ are values of r that is known to produce chaotic behavior

and a,b,c,d are coefficients

10:59 AM

prove what?

that chaotic behaviour of a function f is a series of the function f of higher and higher iterations, analogous to a power series where you have higher order terms in the form of powers

So unless there's a math theorem (that I am not aware of) that say this is false, It is possible that chaos might be some kind of a linear combination of functions of different iteration orders

you need to define things better ;-)

how do you define chaos?

(I don't want an answer, just that you clear things in your mind)

only when you have a satisfactory definition of things, you can try to prove something

a very famous mathematician/physicist, James Glimm said:

"A good definition should be the hypothesis of a theorem"

3

;-)

Q: What will happen if there is large amounts (massive) of electrons in a region?

11:23 AM

0

For large amount of hydrogen, they will be bound by gravitation force, start fushion and become a star, how about electrons? Will they also "fuse"?

electrons

Dammit xkcd

11:41 AM

Hello the @0celo7

Frenchman.

So where the hell is @yuggib from, anyway.

His name is big guy backward

So probably American

Racist

@0celo7 Forum cornelii

Sounds like...Yugoslavia? Dunno

11:46 AM

Forum Cornelii è il nome antico dell'odierna città di Imola. La città mantenne tale nome lungo tutto il periodo di Roma antica. Il nome Imola risale agli inizi del VII secolo.

apparently he is in Ancient Rome

exactly

actually, it was cisalpine gaul originally

France?

That's a long way from Yugoslavia.

cisalpine gaul was mostly not in france

Ok, some more trivia. This is tricky.

@yuggib Says you

11:54 AM

@Slereah Give us back the wedding at Cana

and all the others

a country of thieves... :-P

@yuggib : That will teach you to invade Gaul!

(and anyways, even in your map cisapline gaul is mostly not in France)

Well it is a protectorate of France :p

@Slereah I was in Gaul in the first place.... :P

And now here you are

Chumming up with Cesar!

What would Vercingetorix say

12:15 PM

probably something unintelligible

12:35 PM

http://www.tcd.ie/Physics/Foams/Lecture_Notes/PY2T20ChaosAndComplexity/chaos_complexity2014.pdf
A nice gentle introduction to chaos theory

I think I might have enough background to seek fir the counterexample

you know what I'm gonna ask

are you gonna ask for a diagram

product, of the gross domestic variant

ew gross