The h Bar

ACuriousMind

5:00 PM

@0celo7 ¿¿¿

0celo7

@EmilioPisanty wasn't h functional analysis?

Slereah

The Planck length itself shows up in a few various situations

0celo7

Crap, I mean dimensional

Slereah

For instance it shows up in the path integral for the Einstein Hilbert action

Emilio Pisanty

@0celo7 not really

Slereah

5:01 PM

it's the coupling constant of spinor fields to torsion

that kind of stuff

0celo7

@EmilioPisanty he saw that E and f were linearly related, so the constant is h

Emilio Pisanty

@0celo7 yeah, but the value itself is through a fit to experiment

0celo7

Oh, sure

AccidentalFourierTransform

@0celo7 that is the modern explanation

Emilio Pisanty

as opposed to the length of the Planck length, which is obtained through dimensional analysis

AccidentalFourierTransform

5:02 PM

that is the photoelectric effect actually, that was Einsteit

0celo7

@ACuriousMind &&&

AccidentalFourierTransform

Planck was playing around with oscillators and thermodynamics

Jaime Gallego

@0celo7 ‽‽‽

0celo7

Why does that symbol exist lol

AccidentalFourierTransform

Why does that symbol exist‽

ACuriousMind

5:03 PM

It's the Interrobang

Emilio Pisanty

what, the interrobang?

Interrobang.

...

¼εfè─$uF┌▓→

How do people know that?

Jaime Gallego

5:03 PM

I see we've gone full Unicode.

Emilio Pisanty

@JaimeGallego maybe you're confusing it with this one?

Irony punctuation

Irony punctuation is any proposed form of notation used to denote irony or sarcasm in text. Written English lacks a standard way to mark irony, and several forms of punctuation have been proposed. Among the oldest and most frequently attested are the percontation point proposed by English printer Henry Denham in the 1580s, and the irony mark, used by Marcellin Jobard and French poet Alcanter de Brahm during the 19th century. Both marks take the form of a reversed question mark, "⸮". Irony punctuation is primarily used to indicate that a sentence should be understood at a second level. A bracketed...

Yashas Samaga

Tutorial to add unicode symbols: Hold ALT and type a number using the numpad; release the ALT after you are done typing the number.

AccidentalFourierTransform

and what is the punctuation mark for sarcasm? I remember that that was a thing

Emilio Pisanty

⸮

AccidentalFourierTransform

ah yeah, that was it

Emilio Pisanty

5:04 PM

@Slereah oh, that's mighty helpful

emtpy tallish rectangle?

AccidentalFourierTransform

and then we have

Minkowski's question mark function

In mathematics, the Minkowski question mark function (or the slippery devil's staircase), denoted by ?(x), is a function possessing various unusual fractal properties, defined by Hermann Minkowski (1904, pages 171–172). It maps quadratic irrationals to rational numbers on the unit interval, via an expression relating the continued fraction expansions of the quadratics to the binary expansions of the rationals, given by Arnaud Denjoy in 1938. In addition, it maps rational numbers to dyadic rationals, as can be seen by a recursive definition closely related to the Stern–Brocot tree. == Definition... ==

ACuriousMind

I see a code block. What symbols are those supposed to be?

0celo7

Doesn't that question mark violate Poe's law?

Slereah

It is a very good symbol

0celo7

@ACuriousMind I see a penis

AccidentalFourierTransform

5:05 PM

@ACuriousMind a dick. Suspend them

ACuriousMind

Very original, people :P

0celo7

Looks like it is ejaculating

AccidentalFourierTransform

╰⋃╯

Slereah

Can't get banned for a unicode symbol

Emilio Pisanty

@AccidentalFourierTransform that's still easier to write than

Weierstrass's elliptic functions

In mathematics, Weierstrass's elliptic functions are elliptic functions that take a particularly simple form; they are named for Karl Weierstrass. This class of functions are also referred to as P-functions and generally written using the symbol ℘ (or ℘ {\displaystyle \wp } ), and known as "Weierstrass P"). The ℘ functions constitute branched double coverings of the Riemann sphere by the torus, ramified at four points. They can be used to parametrize elliptic curves over the complex numbers, thus establishing an equivalence to complex tori. They also yield...

Mostafa

5:06 PM

@YashasSamaga ♥☻♣o☺♠

Yashas Samaga

‼

AccidentalFourierTransform

@Slereah I was once banned for posting a swastika :-(

Yashas Samaga

^ note that that is one character not two

Emilio Pisanty

^ that is awesome

Slereah

apparently the translation for exponential map is just literal

La carte exponentielle

Emilio Pisanty

5:06 PM

@Slereah what's wrong with that?

0celo7

@ACuriousMind you're not deleting it?

Mostafa

Why is it Weierstrass not Wierstrass?

Slereah

I dunno, "carte" is a bit odd here?

0celo7

This is why Sofia left

PSE chat is porn now

ACuriousMind

@Mostafa It's actually Weierstraß

Slereah

5:08 PM

It's actually $\mathfrak{Weierstraß}$

ACuriousMind

And there's an 'ei' because that's how Germans write that sounds

Jaime Gallego

@Slereah There's no blackletter esset?

Slereah

apparently not

Mostafa

@0celo7 Everything is porn in some way....

Slereah

which is odd because Germans love Fraktur

AccidentalFourierTransform

5:10 PM

...

?!?

he's gone!

he aint coming back?

ACuriousMind

@0celo7 A unicode symbol is not "rude or offensive" on its own.

AccidentalFourierTransform

till 2018!?

0celo7

A penis sure as hell is

AccidentalFourierTransform

and what about four unicode symbols?

are u, k, c, f offensive on their own?

Yashas Samaga

in JEE Preparation, 8 mins ago, by Koolman

Emilio Pisanty

5:13 PM

@ACuriousMind also that is not a single unicode symbol

Yashas Samaga

Do you take two times of the reduction potential of Fe3+ to Fe2+ in that reaction to calculate the E.M.F?

E = E_cathode - E_anode

AccidentalFourierTransform

0

Q: Derivation of the De-Broglie wave relation

I've just tried to make sense of the De-Broglie wave relation. That is what I came up with: $E=mc^2$, but $E=hf$ as well. $\lambda=vT$ so $f=\frac{v}{\lambda}$. Equating the two equations for energy you get $mc^2=h\frac{c}{\lambda}$ because for light the velocity is $c$. $mc$ is just the non-rela...

this question, again?

0celo7

@ACuriousMind Holy shit, you unbanned him?

ACuriousMind

@EmilioPisanty What isn't?

0celo7

What happened to the rule of law?

Emilio Pisanty

5:15 PM

@ACuriousMind AFT's symbol here

ACuriousMind

@EmilioPisanty I wasn't talking about AFT's symbol, I was talking about Slereah's Egyptian hieroglyph which was flagged.

2017

@YashasSamaga No. However, it is always best to solve it using the Gibbs Energy method.

Yashas Samaga

@2017 Gibbs Energy was the source of the problem.

I am somehow getting two

Emilio Pisanty

@ACuriousMind oh

Yashas Samaga

E = -nF \Delta G

Emilio Pisanty

5:17 PM

no idea what that was

Yashas Samaga

n = 2?

Mostafa

@ACuriousMind Link + screenshot please

ACuriousMind

@EmilioPisanty Googling tells me it was U+130Bx/A as seen here

Yashas Samaga

@2017 n = number of electrons involved in the reaction

nvm, I am doing some stupid things

2017

@YashasSamaga Why should n be 2 ? You need to consider 'n' factor over here. It changes state from +3 to +2...

n=1

Emilio Pisanty

5:19 PM

@ACuriousMind oh

yeah

Yashas Samaga

yea it is 1

2017

n stands for n factor...

in such cases

Koolman

@2017 for Sn n=2

2017

Yes.

Yashas Samaga

ok I did not make a stupid mistake

@2017 can you write the Gibbs equation for the final reaction

I am getting 2E_cathode for some reason

nvm

2017

5:23 PM

$$-(2)FE_{net}=2(-1FE_{Fe})+(-2FE_{Sn})$$

Yashas Samaga

I used E = nF\Delta G all the time

even though I knew the correct equation

John Rennie

@ACuriousMind On Windows 10 both Chrome and Edge just show the square. However some determined Googling has found the symbol for Egyptian hieroglyph d053. Those naughty Egyptians :-)

Yashas Samaga

I am becoming more and more stupid as the exam date is approaching closer

2017

@YashasSamaga You are spending way too much time on this website (just a constructive criticism...)

Yashas Samaga

Or i need to sleep

Knowing that y = kx and then using x = ky while solving is 100% an indication of brain not functioning properly

I need to sleep

I have got just 8 hours in last two days

0celo7

5:27 PM

@ACuriousMind Can you please clarify PSE's policy on images of ejaculating penises? Is it OK if the resolution/detail is low enough?

Koolman

@YashasSamaga yeah you need sleep

@2017 by this the ans2er would be different

Mostafa

@JohnRennie Same for me but I gave up after some Googling :/ Nice job

@0celo7 Define low enough.

AccidentalFourierTransform

Can I photoshop a female nipple over a male breast? or viceversa? would that be considered offensive?

0celo7

@Mostafa That's what I would like some advice on.

If penis pictures are ok then this chat is about to get hella lit!!

John Rennie

@Mostafa I find it mildly reassuring that humans were drawing willies on walls 5,000 years ago. It's nice to know we haven't changed in that time :-)

Mostafa

5:31 PM

@0celo7 One way is to start posting with very low resolutions and gradually increase it. Once you get suspended, that's the threshold.

2017

No. It will be okay. 0.77+0.14

0celo7

@Mostafa Vaginas must be ok too, no sexism here!

2017

@Koolman

John Rennie

Speaking as a room owner (not a moderator) you'll need a very convincing reason for arguing that pictures of body parts have any relevance to physics.

Koolman

@2017 why E are not additive

Mostafa

5:33 PM

@JohnRennie They can be related to biophysics.

2017

@Koolman Because Gibbs energy is the governing factor here...

0celo7

@JohnRennie I would just like an explanation as to why @Slereah sentence was commuted.

2017

E is not additive...

John Rennie

@0celo7 why is that any of your business?

Koolman

@2017 how

0celo7

5:33 PM

Because right now it seems like the moderators are condoning penis pictures.

@JohnRennie Because I would like to know if I can post pictures of penises, clearly.

John Rennie

You cannot.

0celo7

For medical reasons, of course.

John Rennie

At least not while I am a room owner. I trust that is clear.

0celo7

@JohnRennie Then I am confused as to why my confirmed flag was overturned by a moderator.

2017

@Koolman Conservation of energy...

4

A: Why exactly are standard potentials additive?

Following on Derek's great answer, it is very important to remind that the conventional way we use to add half-cell potentials is a consequence of the conservation of energy. Therefore, we should look at this from the perspective of Hess's Law. How so? Well, if we add two reactions, no matter w...

John Rennie

5:35 PM

@0celo7 why is that any of your business?

Mostafa

@JohnRennie Here is more reassurance for you, this time in ancient temples in India.

0celo7

@JohnRennie It indicates the moderators are in favor of it.

Are you saying I don't have a right to know what the moderators approve of?

2017

@Mostafa Ah, I visited them some years back with parents. It was embarrassing. :P

John Rennie

@Mostafa I think there are Cro-Magnon carvings that are pretty explicit, so that pushes the boundary back 50,000 years or so :-)

0celo7

Wonder what the first explicit depiction of a sheep is.

@JohnRennie is old enough to know.

John Rennie

5:37 PM

Mesopotamia I would guess ...

0celo7

I should make a meta post.

Mostafa

The ultimate guide here

ACuriousMind

@0celo7 I do not approve of such pictures. But I considered the ban excessive, especially in light of it being you who cast the flag, clearly to get Slereah banned. That's all I'll say on this matter.

0celo7

@ACuriousMind I think its reasonable to suspect someone viewing the chat might get a PTSD attack from seeing such an image. Would you have deleted it and not suspended him if I had not flagged?

Slereah

Man chapter 1 of Munkres goes on and on

I didn't expect him to do the axiom of choice

0celo7

5:42 PM

You need it for the Tychonoff theorem.

Slereah

Does it mean that topology is a lie then

0celo7

It means that an infinite product of compacts need not be compact

Although IIRC an infinite product of nonempty sets is empty without C

Yashas Samaga

0

A: Derivation of the De-Broglie wave relation

de Broglie suggested that a moving body behaves in certain ways as though it has a wave nature. His conjecture of dual nature of matter was based on two points : (1) dual nature of radiation, and (2) nature loves symmetry. de Broglie deduced the connection between particle and wave properties fr...

is the last part correct?

You treat the electron to be wave moving in a circle.

multiples of the wavelength = circumference

AccidentalFourierTransform

@YashasSamaga I think so, yes

Yashas Samaga

what if n = 1?

the wave is a perfect circle?

AccidentalFourierTransform

5:46 PM

A Perfect Circle - The Noose

►

Slereah

Also Munkres' definition of $\Bbb N$ is slightly odd

Yashas Samaga

integral fraction

that oxymoron

Slereah

Well, $\Bbb Z_+$

He defines it as the intersection of every inductive set on $\Bbb R$

2017

@YashasSamaga They are standing circular waves...

"Wave is a perfect circle" makes no sense

Yashas Samaga

I have seen that wave thing in many JEE textbooks

but they never tell what they do

0celo7

5:48 PM

@Slereah that's the usual one

Slereah

Is it

0celo7

JEE?

What's that

Slereah

I usually see $\Bbb Z$ defined before $\Bbb R$

2017

@YashasSamaga Check out Wikipedia...JEE books aren't detailed enough

@JaimeGallego He was being sarcastic. He knows what it is.

AccidentalFourierTransform

lol

Yashas Samaga

5:49 PM

@JaimeGallego He already knows that lol

Slereah

$\Bbb Z_+$ is pretty easy to define from set theory

0celo7

I usually see $\Bbb R$ before set theory

Jaime Gallego

raises Sheldon Cooper sarcasm banner

0celo7

what?

2017

@JaimeGallego 0celot7 gets PTSD attacks on seeing anything related to JEE. :'D

0celo7

5:53 PM

it's true

2017

Agreed ^

AccidentalFourierTransform

0

Q: Is this socks theory correct?

Here are the few images I have taken from Quora. First Image is the question and last two are the answer written by some users. I want to know are there answers real and consistent with physics?.

quantum-mechanics

6

sigh

Yashas Samaga

OMG

I am leaving this Earth today.

2017

Someone take a screenshot of that question ^

:P

Actually I want to upvote that question. It made me laugh after a long and tiring day :)

Yashas Samaga

Measure the Speed of Light with a Chocolate Bar

►

1. There two doppelgangers of Hermonine

2. How does that work?

Why should spots where the wavelength ends must be heated the most?

John Rennie

6:09 PM

@YashasSamaga The microwaves form a standing wave inside the oven so you get points of maximum intensity and nodes where the intensity is low. The chocolate remains unmelted at the nodes and melts at the maxima.

Yashas Samaga

Ah! Now it makese sense. Hurray for standing waves.

DanielSank

@alarge I never previously understood what $$\int_0^T dW_t$$ meant. I do now, so thank you, very much, for your constant help.

Yashas Samaga

Why has a wrong answer been upvoted the most?

physics.stackexchange.com/questions/357/home-experiments-to-derive-the-speed-of-‌light/901

DanielSank

@YashasSamaga First of all, what makes you say it's wrong?

It's a very clever experiment and the author reports that it gives an answer only off by a factor of order 1. That's pretty good for measuring the speed of light from your desk chair.

Yashas Samaga

order 1, that is what he stated

every packet goes through countless routers

there is a calculation overhead

it is unpredictable

if there is heavy lag, your ping could skyrocket to 1000s

@DanielSank khanacademy.org/computing/computer-science/internet-intro/…

DanielSank

6:20 PM

Yes it's unpredictable. It's still a good idea as something to check. If nothing else, you get a lower bound, which is useful and you can do it in seconds from your computer!

If you really don't think that's worth upvoting, then don't upvote and move on with your life.

Yashas Samaga

Isn't it wrong?

DanielSank

@YashasSamaga It gives a lower bound.

I have edited the answer to make this clear.

Yashas Samaga

some people might get the lower bound as 10,000 miles per second

some might get 100,000 miles per second

I removed my downvote though.

DanielSank

@YashasSamaga Then edit it to be more clear.

Yashas Samaga

its better now

Mostafa

6:30 PM

14 hours ago, by 2017

@Mostafa Hmm. In most problems like this we assume that the transistor is in active state. Why would be consider cut-off region or saturation region anyway when amplification is not possible? These problems are based on specific concepts which we need to identify. Here in this case they want to test a students knowledge of the relation between base current and collector current when electrons are injected from common emitter in active state.

Because signal amplification is not the only use of transistors.

Jacobadtr

Hi,

if I have determined a wavefunction, and want to know how it would evolve given a sudden change in the potential, can I simply plug my initial wave function into the TDSE with the new hamiltonian?

Specifically, going from a 1d infinite potential well in the ground state, to a free particle suddenly

DanielSank

@Mostafa Yeah, like in mixers.

@Jacobadtr Yep.

Jacobadtr

@DanielSank Great, thank you!

Slereah

Is using a lot of Fraktur a category theory thing?

DanielSank

What's Fraktur?

Mostafa

6:41 PM

\mathfrak in LaTeX?

AccidentalFourierTransform

What's LaTeX?

DanielSank

@AccidentalFourierTransform A typesetting language.

Most physicists and mathematicians use it for articles/books/etc.

AccidentalFourierTransform

I was expecting "\LaTeX in LaTeX?" but ok

Slereah

$$\mathfrak{This is fraktur}$$

0celo7

@DanielSank :(

@Slereah you need spaces

Slereah

6:52 PM

$$\mathfrak{No}$$

0celo7

@Slereah when I write my thesis I will use fraktur for weak solutions

AccidentalFourierTransform

@0celo7 are you breaking up with him?

Slereah

use some cyrillic symbols for a change

Mostafa

@Slereah and some Egyptian hieroglyph in...maybe acknowledgments.

Slereah

It's pretty hard to find egyptian packages for Latex

AccidentalFourierTransform

6:58 PM

boobs.

Yashas Samaga

0

Q: Were there any mathematically sound physics theories that turned out to be wrong?

What are some (if any) mathematically elegant/sound theories of physics that turned out to be wrong?

experimental-physics

0celo7

Please delete that...

Yashas Samaga

@AccidentalFourierTransform clickbait?

AccidentalFourierTransform

no. Just boobs.

D3075

hi how is $\partial_\mu$ related to $d^4x$

AccidentalFourierTransform

7:02 PM

no obvious/straightforward relation

D3075

oh

AccidentalFourierTransform

(we could get pedantic and say that $\partial_\mu$ is a basis of the tangent plane and $\mathrm d^nx$ is a basis of $T^*_nM$ or whatever the proper notation is)

Hi there

Slereah

The cotangent bundle

Mostafa

@AccidentalFourierTransform you've been featured here .

AccidentalFourierTransform

@Slereah I mean, if $\omega\in T^*M$, where does $\mathrm d\omega$ live?

or rather, $T^*M\overset{\mathrm d}{\longrightarrow}?$

Slereah

7:10 PM

$d$ maps the exterior bundles

$$d : \Lambda^n \to \Lambda^{n+1}$$

or something

AccidentalFourierTransform

@Mostafa lol

Slereah

$d\omega$ would be a 2-form, so in the assymetric part of the $(0,2)$ tensor bundle

AccidentalFourierTransform

@Slereah and what is the proper notation for the highest $\Lambda$ before hitting zero?

$\Lambda^n\to\Lambda^{n+1}\to\cdots \to ?\to 0$

Slereah

I don't think it has a special name?

It's the space of pseudoscalars, I suppose

I don't think it has a specific symbols

AccidentalFourierTransform

where does the volume form live in?

Slereah

7:13 PM

There, yes

AccidentalFourierTransform

$\mathrm d\text{vol}\in\Lambda^?$

Slereah

Hm, wait

AccidentalFourierTransform

is there a specific notation for that?

Slereah

I'm not sure

Is the volume form part of the pseudo scalars or are there weights involved, too?

AccidentalFourierTransform

IIRC the volume form is a proper tensor

not pseudo

Slereah

7:15 PM

Pseudoscalars are tensors, yes

But that's not what i mean

AccidentalFourierTransform

anywayz, its not that important

whatever

Craig Gidney

I was wondering what the quantum equivalent solution of the "biased random walk off a cliff" problem is (example of the classical problem: math.stackexchange.com/questions/359989/… )

You can't quite do the exact same problem with amplitudes in place of probabilities, because the steps have to be reversible. So what I had in mind was something like...

You have a 2-state unitary operation, and you alternate back and forth between applying it at even splits and odd splits.

0celo7

I hear geometry

Craig Gidney

e.g. if U was the Hadamard operation then (ignoring factors of sqrt(2)) the state would go...

$|0\rangle \rightarrow |0\rangle + |1\rangle \rightarrow |\text{fall}\rangle - |0\rangle + |1\rangle + |2\rangle$

DanielSank

Look, @0celo7, Hadamard!

Craig Gidney

7:19 PM

Then you'd measure fall-vs-not-fall, kicking it out of the system, and continue.

And the question is, given $U$, how likely is it that a quantum walker eventually fall off the cliff?

DanielSank

Way better set of answers for the classical problem:

37

Q: Does the drunk man fall off the cliff? (a random walk problem)

A drunk man stands with a cliff one step to his left. He takes steps randomly left and right. Each step has probability $p$ of going left and probability $q=1-p$ of going right. Each step is the same size. If allowed to randomly step indefinitely, what is the probability that the drunk falls off...

mathematics probability

John Rennie

→ 1 message moved to Trash

AccidentalFourierTransform

:-(

John Rennie

If you're going to be obscene at least make it funny.

AccidentalFourierTransform

they did look like testicles

I was not trying to be funny

Craig Gidney

7:23 PM

Solving the classical problem is much easier because you can add probabilities from different times, e.g. by waiting for all the probability to "drain out of" a small section to figure out the long-term behavior. But with amplitudes you need all the contributions before you can square to get the "weight" of a time slot, so you can't focus on a narrow slice as easily because the stuff that leaves and comes back seems to matter.

Basically, the "slices" you make need to be spacelike instead of timelike.

0celo7

@DanielSank aha

Mostafa

@Slereah p.84

Slereah

@Mostafa Those are only single letters

there's no determinatives

Mostafa

@Slereah Hmm, try drawing it in detexify . Too difficult for me to draw accurate enough. This may be a better starting point. (courtesy of AFT)

Slereah

Let's make a math paper entirely in hieroglyphic

AccidentalFourierTransform

7:35 PM

#MadLads

Slereah

starting to run out of room

AccidentalFourierTransform

"How to teach Relativity to your dog"

?

Slereah

Well, how else would you teach it to a dog

AccidentalFourierTransform

@Slereah throw away gradshteyn and ryzhik and abramowitz and stegun

Slereah

Never

Mostafa

7:47 PM

@AccidentalFourierTransform was typing exactly this when you posted it

AccidentalFourierTransform

its the obvious solution

big ass and useless books

Slereah

Gradshteyn and Abramowitz is just enough books to kill you both

John Rennie

@Slereah buy another bookcase?

Slereah

Well I plan on buying a flat soon-ish

I guess I'll buy a new bookcase then

It should be a slightly bigger flat

I have a lot of books split in two

Bloody paperbacks

AccidentalFourierTransform

Jun 14 '16 at 16:52, by Slereah

I broke its spine by accident since it is so big

Slereah

7:51 PM

Yeah

it' a big book

I wonder if it's possible to buy a second hand particle data group book

Let's see

amazon.com/Review-Particle-Properties-Anniversary-LBL-100/dp/…

yesss

speaking of big useless books

DanielSank

For all the help you guys have given over the years, I offer this: on the pcb project I'm working on, I will include a logo of your choice somewhere in the silkscreen.

2

AccidentalFourierTransform

a swastika

DanielSank

Perhaps the PSE logo.

To do this, I need a DXF of the logo.

Slereah

You are aware that we're gonna give you a dong, right

DanielSank

@Slereah Sure, but I won't include anything that will get me fired.

So go ahead and argue for a dong. I'll just ignore it.

Slereah

7:57 PM

Then the problem will be artfully hiding the dong

Negative space, perhaps

AccidentalFourierTransform

is this artful enough?

DanielSank

10, 9, 8, ...

^ countdown to deletion

Mostafa

@DanielSank What about the starred hieroglyph?

AccidentalFourierTransform

ok Ill behave

Slereah

Oh man

You can still order the 2016 book for free!

2016 Review of Particle Physics (914 pages, Listings only online) order placed: 27 February 2017, 11:59am GMT-08:00
2016 Particle Physics Booklet (condensed report; 344 pages) order placed: 27 February 2017, 11:59am GMT-08:00

Yessss

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