The h Bar

12:07 AM

@BernardoMeurer Not before finals.

I think I haven't mentioned this before, but we've got an exam on P.E. theory. Badminton theory!

It's crazy, considering that the teacher copies all the notes from particularly low-quality Wikipedia articles, verbatim.

The ones with red banners and [citation needed] on every paragraph.

ACuriousMind

@JaimeGallego You have P.E. theory?

Jaime Gallego

Yup, each trimester we have a different sport, and we have to study the rulebook, measurements of the field, etc.

Prolly the only school in the whole of Madrid that does this. It's baffling.

ACuriousMind

Heh, our PE class was always just "Okay, here are the rules, go play the game"

If they even bothered to tell us the rules :D

Secret

12:22 AM

Actually for both classical and quantum, suppose I shine unpolarised white light into a black box (which contains the experimental setup itself) and I get blue linearly polarised light in the end, then in principle I cannot deduce what's in the black box other than there exists at least one polariser and blue filter (that is until i look into the black box)?

So I guess regardless of which interpretation of quantum, you need to know some information on the experimental setup in addition to the information from the measured statistical distribution of the observables in order to calculate the correct distribution of observables?

Mathematically, if $S$ and $S'$ are ordered sequence of operators, then there exists $S$, $S'$ such that their eigenvalue decomposition is identical

Jaime Gallego

@ACuriousMind Good news is that the PE exam is the last one, and after that, freedom. I might get around to learn QM and multivar calculus after that, get more involved in PSE.

Maybe get a CS internship somewhere.

ACuriousMind

Freedom as in "done with school" or as in "no more PE exams"?

Mithrandir24601

@Secret I wouldn't even assume that - how do you know e.g. that it's not just a polarised blue light source?

Jaime Gallego

Both.

ACuriousMind

A PE theory exam is your final school exam? oO

Secret

12:34 AM

@Mithrandir24601 ah right, no one can tell that based on observing the blue light alone

Jaime Gallego

It happens to be the last one for this year. I've still got another year left before uni.

College exams are on May-June 2018.

ACuriousMind

Ah, okay

DanielSank

@Mithrandir24601 sure

Captain Bohemian

1:36 AM

college exames were in 2000

DanielSank

7:12 AM

@heather @BernardoMeurer @Danu @ACuriousMind @dmckee This music video, the visuals and the audio, is running on a Commodore 64... in a program only 256 bytes long.

A Mind Is Born (256 bytes)

►

5

Avantgarde

AI music

user228700

@JohnR: Morning! :-)

John Rennie

Morning. How's the power supply?

SBM

good afternoon
typos

Avantgarde

yo typo

I mean SBM, hahaha

what did I just write

user228700

7:25 AM

@JohnRennie ...it's alright. Haven't charged it since yesterday evening.

user228700

@Avantgarde x'D

Avantgarde

Welcome, mithrandir

John Rennie

@SBM I was wondering which god you were saying "afternoon" to :-)

user228700

Wow, did I get this party started or or what? :-P

John Rennie

@Kaumudi.H did you see my message about the subtitles?

SBM

7:26 AM

@JohnRennie It was a typo I make a lot of them

sadly

user228700

@JohnRennie Crap, I have seen it just now.

John Rennie

@SBM as do we all. At least here you can go back and edit the mistakes. On Facebook Messenger and Google Hangouts your errors are permanently there for everyone to see!

SBM

right

John Rennie

@Kaumudi.H: is the laptop still electrocuting you!

Avantgarde

Mithrandir24601

7:35 AM

Mornin'

@DanielSank Thanks :) I owe you a beer-equivalent. Is it OK if I send you an e-mail at some point then? (by the way, my real name's Ross and I'm at Bristol)

user228700

This is the very first thing that comes to mind when I hear "Ross" :-P

Mithrandir24601

@Kaumudi.H Dear goodness, no :P

Slereah

stringwiki.org/wiki/String_Theory_Wiki

good logo

DanielSank

8:20 AM

@Mithrandir24601 yeah, email me

ಠ_ಠ

10:02 AM

Anyone happen to know where I can find an image showing the orbits of the Lorentz group in Minkowski 3-space (i.e. null cone, hyperboloid of 2 sheets, de Sitter space)? I'm trying to put together a powerpoint and I'd prefer not to have to draw it on the board to save time.

Emilio Pisanty

10:30 AM

1

Q: How can the 1/Z dependence of the ionization of Helium-Like atoms be explained?

בס''ד Helium is a widely used gas, second lightest to Hydrogen in the Periodic Table. The Hamiltonian for the Helium Atom is: The term "M" scales with the Mass of the number of Protons in the nucleus. These Protons in turn can be decomposed into Positrons and Neutrons pairs under specific bo...

ionization-energy

^ could use some attention

Jim

11:47 AM

Physicists of all ages, I, the all mighty Jim, welcome everyone to the first annual Physics Pun Day

And with me here, you can be sure this day is going to be Jim Dandy

Bernardo Meurer

12:07 PM

@dmckee @JohnRennie I just passed Computer Architecture without attending any classes, woohoo

John Rennie

@BernardoMeurer whoo hoo :-)

Bernardo Meurer

@JohnRennie I read the material 2h before the exam and still passed, meanwhile 1/3 of the people have already failed the course (i.e. redoing one exam won't save them)

THANKS COMPUTERS

Mostafa

@BernardoMeurer Great, I also passed around 40% of my undergrad courses without attending any classes and doing any homework.

@EmilioPisanty Done, though it's still a very unclear question.

user228700

12:44 PM

@JohnR: Oh, you're back! :-)

John Rennie

Hi :-)

user228700

Watched Her, BTW. It was brilliant.

John Rennie

You'll have to ration the films :-)

Unless there are others on the list that you want.

Bernardo Meurer

@Kaumudi.H Watch Apocalypse Now

And The Seventh Seal

And Full Metal Jacket

Killer movies

user228700

@JohnRennie Yeah, yeah :-( But I'm almost done watching them all. I only have that documentary about Edward Snowden left...

user228700

12:47 PM

And two of the Wallace & Gromit short films.

user228700

@JohnRennie Nope :-/

user228700

@BernardoMeurer I'm not really into movies like those but I try to be open-minded so I will check it out...

Bernardo Meurer

@Kaumudi.H Those three movies are fairly different, so I'm not sure you can group them under "those"

user228700

They're sort of similar to me, not in terms of genre but in terms of the, OK, this is difficult to explain. Never mind.

Bernardo Meurer

Glad you jumped out before you dug a hole too deep :P

John Rennie

12:53 PM

@Kaumudi.H: lunch!

user228700

What is it?

John Rennie

They are kind of pakoras, assorted.

user228700

Ooh, cool :-)

John Rennie

Vegetarian as well!

Jim

So yesterday, we had a charge sensor that we use for one of our labs out and were tinkering with it. We thought it'd be a good idea to find out how much static charge a person can generate. We tested a few people and found that a person will measure at $<1nC$ on the sensor normally and, after attempting to charge themselves up, will measure at around $3nC$. Then we tested me....

Bernardo Meurer

12:59 PM

@JohnRennie Going for the best burgers in Lisbon today

Jim

Uncharged, I measured at around $3nC$ and from sitting for a quick moment in any chair and standing up, I maxed out the sensor at over $77.5nC$. Apparently I generate more charge than an average human by more than an order of magnitude

One can say I was shocked by the results

John Rennie

@BernardoMeurer Burgers, mmm :-)

Bernardo Meurer

@JohnRennie I still gotta have the ones you make :P

Mostafa

Last night I wanted to order a pizza.
There was something called *mac pizza* for a third of the usual price of a pizza. I thought it's just a smaller pizza and ordered two (online).

This is what I got:

Jim

is that a pizza burger?

Mostafa

1:05 PM

I think so. (But never heard of it before)

Jim

I can feel the cholesterol clogging my arteries just looking at it

Mostafa

Actually I couldn't sleep last night (feeling of *heavy* stomach; and getting unusally thristy).
I finally felt normal in the morning :-)

Jim

@Mostafa You want to drink tea for that feeling. No idea if it actually helps or not, but tea is always a good idea and, perhaps, the placebo effect can at least do something for you

John Rennie

@Mostafa: no, you just need more practice eating Mac Pizzas :-)

Mostafa

Thanks I'll try it next time
(but hope it never happens again:)

Whenever I eat fast food I say **never again**
But after some time, again....

@JohnRennie NEVER AGAIN :P

I normally eat very healthy because my grandma cooks.
Whenever she's not here, like now, I have to order food.

Balarka Sen

1:36 PM

@Bernardo @Kaumudi The Seventh Seal is excellent.

I second it.

I personally haven't seen Apocalypse Now but it's based on Joseph Conrad's Heart of Darkness, and I really like his novels. I have that movie on my to-watch lists.

user228700

It looks interesting but I don't know how to play chess. I know the rules and all, but not how to play it well.

Balarka Sen

well definitely fix that. it's not a movie about chess :)

user228700

It does have a lot of chess, doesn't it?

Balarka Sen

Ingmar Bergman is one of the leading figures in European art films in his time, along with Bresson, Fellini and my personal favorite Andrei Tarkovsky

i mean sure but you don't need to appreciate chess to watch the movie :P

user228700

@BalarkaSen Ohh, cool.

user228700

1:42 PM

Got a different impression from the synopsis.

Balarka Sen

i think most of my favorite movies have terrible synopsis in wikipedia

Slereah

@BalarkaSen Is it Fart, the Movie

F.A.R.T. the Movie

F.A.R.T. The Movie is a 1991 low budget independent comedy film co-written, produced, and directed by Ray Etheridge. == Plot == Russell (Joel Weiss) is obsessed with farting, and loves to fart any time he can. His girlfriend, Heather (Shannandoah Sorin) despises farts and becomes angry with Russell because all he does is watch television and fart. She tells him that the only time she can feel relaxed is when Russell is out of the house, as she is away from his gas. She thinks that if the television turns into fart jokes, which he also loves, then Russell won't even leave the house. Then one night...

Balarka Sen

uh

no

Slereah

poorly received, apparently

quite shocking

user228700

@BalarkaSen Oh, that sucks for someone to whom you recommend one of them :-/

Slereah

1:49 PM

@BalarkaSen Are all spin groups double covers of $SO$?

$SO(1,1)$ is just two copies of $\Bbb R$ but its spinors are still sections of $\Bbb C^2$

Balarka Sen

I don't usually recommend my stuff to people unless I know their artistic tastes have something in common with mine. I imagine most of my favorite films/literature/whatever would not be thought as great stuff to THE pUbLiC

John Rennie

@Slereah I think we should put that behind us.

Balarka Sen

@Slereah Spin(n) is a double cover of SO(n). I don't know much about SO(p, q).

What are those?

Slereah

SO for metrics of signatures (p,q)

In particular $SO(1,1)$ is the Lorentz group in 2D

Balarka Sen

Ah right

and how's Spin(p, q) defined?

Slereah

1:53 PM

The usual, intersection of the even Clifford group and the Pin(p,q) group

Balarka Sen

oh, i dunno much about that

@Slereah here's what wikipedia has to say

Slereah

I know what wikipedia has to say :p

Hm, what place could have it

user228700

@JohnRennie God, I knew this was coming x'D

John Rennie

@Kaumudi.H I hate to disappoint my audience :-)

Ger Wyn

Hello! Can anyone provide me the contents of Maths that a grade 12 student should know? (Not in particular to any specific course)

Lozansky

2:18 PM

What does the notation $\big \langle ... \rangle$ mean? As for example the gravitational wave luminosity $L_{GW} = \dfrac{G}{5c^5}(\mu \Omega a^2)^2 \big \langle 2 \sin^2 (2 \Omega t)+ 2\cos^2 (2\Omega t) \rangle$

Fawad

3:00 PM

Hi. What does "linear size of charged bodies" means?

I am reading electric charges and fields.

Algebra
* Matrices.
* Theory of Equations.
* De Moivre’s Theorem.
* Complex Numbers.
* Mathematical Induction.
* Quadratic Expressions.
* Binomial Theorem.
* Permutations and Combinations.
* Functions.
* Partial fractions.
Trigonometry
* Hyperbolic Functions.
* Properties of Triangles.
* Trigonometric Equations.
* Inverse Trigonometric Functions.
* Trigonometric Ratios up to Transformations.
Vector Algebra
* The Addition of Vectors.
* The Product of Vectors.
Probability
* Measures of Dispersion.

Avantgarde

3:22 PM

@Fawad No idea. Could you provide more context?

Secret

Any infinity people here in h bar can maybe try out this question:

0

Q: Ordinal tetration: The issue of ${}^{\epsilon_0}\omega$

So in the past few months when trying to learn about the properties of the fixed points in ordinals as I move from $0$ to $\epsilon_{\epsilon_0}$ I noticed when moving from $\epsilon_n$ to the next one $\epsilon_{n+1}$, the operation that does that is a left associative operation i.e. $${\tiny⋰}...

ordinals tetration hyperoperation

Fawad

3:35 PM

@Avantgarde

user228700

4:06 PM

@Balarka: Dude, that book came in the mail today, BTW. Gonna start it soon... (I realise that you don't care for these updates but have them anyway :-P)

Balarka Sen

Nice. Let me know what you think of it when you read it.

Jaime Gallego

-1

Q: Help me find book

I want a famous book that talk about antennas and i want this book focus on the physical concept of antennas as well the mathematics .

electromagnetism waves

HELP ME FIND BOOK

"I thought this website is for any question a bout physics and i thought you help me as expected but you Attacking me as i made a crime"

Avantgarde

4:27 PM

@Fawad Thanks. Linear here means a distance scale of dimension 1. This is because it makes sense only to compare the distance between bodies (length dimension = 1) with another length scale of the *same* dimension. In the case of spherical bodies for example, this can be the radius of the object.

Moses

4:39 PM

@ACuriousMind When it is stated that the density matrix in QM is positive, given as $\rho \geq 0$, is that another way of saying that it is a positive semi-definite matrix?

Bernardo Meurer

@Kaumudi.H The Seventh seal has very little to do with the minutiae of Chess, just knowing how the pieces move is enough

ACuriousMind

4:53 PM

@Moses yes

Bernardo Meurer

@ACuriousMind You're not making questions on my AMA

I thought you loved me

What is going on

What have I done

Did I hurt you?

ACuriousMind

I'm not sure what to ask you, I already know about a lot of your drunken wagers ;P

Bernardo Meurer

@ACuriousMind But other's don't :P

AccidentalFourierTransform

The Count Censored

►

@BernardoMeurer I didnt know what to ask either, because I know everything about you already

Bernardo Meurer

@AccidentalFourierTransform Hm? You barely know me

AccidentalFourierTransform

5:04 PM

I know everything about you

Bernardo Meurer

You don't even know my real name

AccidentalFourierTransform

.-.

Bernardo Meurer

Checkmate

AccidentalFourierTransform

Bernardo Meurer

Lol

That's such a glorious picture

AccidentalFourierTransform

5:07 PM

they should do a faceswap with the shirt

Bernardo Meurer

@ACuriousMind Wait, you don't like mangoes?!

What the fuck mate

Fawad

5:20 PM

@Avantgarde ok

user228700

5:37 PM

@BernardoMeurer Oh, OK...

Bernardo Meurer

5:51 PM

@JohnRennie What are your thoughts on Black Flag?

John Rennie

6:14 PM

@BernardoMeurer if I'm honest I really only know the name, and that they're a punk band. But they are close to legendary in the music world.

Jaime Gallego

HEALTH Get Color FULL

►

ACuriousMind

@DanielSank I stand in awe.

Mithrandir24601

6:44 PM

@BernardoMeurer There are an entire three of us that don't like mangoes that regularly use chat! (to my knowledge)

John Doe

7:27 PM

@Mithrandir24601 Hey thanks a lot for such a comprehensive answer, I will work through it and try to understand (answer is a bit intimidating I must admit, but it looks interesting :)).

Mithrandir24601

7:37 PM

@JohnDoe No problem! I kind of thought that a really short, couple of paragraphs answer wouldn't actually explain anything properly (and probably just make things more confusing), so just went for it... So long as it's useful! Feel free to give me any feedback if you feel like it

John Doe

@Mithrandir24601 Great will do.

heather

hello

Mithrandir24601

@heather Rytsas

heather

@Mithrandir24601 rytsas

Sanya

@heather hi~

heather

7:53 PM

@Sanya hello! long time no see

Sanya

@heather unfortunately, I am not around this extremely much anymore

writing a master's thesis was very relaxing, so I had more time to spend here :D

Avantgarde

There is no stairs. Take the success.. You have to elevator

user228700

8:15 PM

Yello. Anyone wanting an old-ass (working) Canon film camera, contact me pls. K thx Bai.

user228700

Here's a photo:

user228700

Avantgarde

Oh wow haha

Is it free?

user228700

@Avantgarde I'm broke. Please sympathise :-P

Avantgarde

:P

That's really old

user228700

8:21 PM

@Avantgarde It is, yeah. It belonged to my parents until they almost threw it ('cause we ain't got Rs. 1000 to buy film to take 20 photos) out before I managed to save it.

user228700

It's pretty useless (it can still take photos but only 20 at a time so) but there must be someone who wants this. Hence the spamming :-P

user228700

@Avantgarde Do u want it if it is?

Avantgarde

Not me, but thanks. Yeah, someone might want it.

Try eBay or something? I've never done that though so idk how that works

user228700

@Avantgarde ...I gotta wait till morning to ask my parents or someone more knowledgable than me if this is worth anything.

Avantgarde

it has the antiquity value

user228700

8:29 PM

Hmm. Anything besides that would be a nope, I guess :-P

Avantgarde

mostly, yeah

Mithrandir24601

There's one on ebay (in the UK) that sold for £9 (+p&p)

user228700

Also, if anybody preparing for JEE wants books from FIITJEE/Resonance, please ping me. I have both, sigh.

Mithrandir24601

Although that included another camera as well, so £4-5 ish?

user228700

@Mithrandir24601 Oh huh, cool. I was just checking to see if anybody was selling...

Anonymous

8:32 PM

@Kaumudi.H I'm willing to buy it....but...next decade :P I'm technically in debt now.

user228700

@blue Why the heck do u need even more books?!

Anonymous

lol, the camera

user228700

Aha, sorry, didn't check.

Anonymous

The JEE books? I'm already thrown them out of my room :P

user228700

@blue Did u actually throw them all?

user228700

8:33 PM

(into the trash, I mean)

Anonymous

Yeah, they are in the verandah now....I will sell them off....or you know...

Anonymous

Some juniors might buy them

Avantgarde

^

yeah

Anonymous

I'll be rich after selling so many books *_*

user228700

Sigh. I have no touch with juniors. And OLX needs me to pay them some money to post more than 3 ads a month.

Avantgarde

8:34 PM

people are always on the lookout for cheap books

user228700

@blue Hopefully, I can too.

Anonymous

I've over 200-300 books on PCM (inluding study materials from different institutes). So I'll get atleast 10,000 rupees :D

Anonymous

(I'm daydreaming though :P)

user228700

This is the state of my room at 2 in the effing morning, sorting through all my JEE shit:

user228700

Avantgarde

8:37 PM

200!

Anonymous

lol ^ that is nothing! lemme show you a pic of my verandah filled with books :P (i need to get hold of a camera first)

Mithrandir24601

@Kaumudi.H That's not anywhere near as bad as I was expecting...

user228700

@blue I have a bunch more books inside my desk and in that other cupboard as well. Several boxes full, actually.

user228700

@Mithrandir24601 Well, I'm trying to organise so :-P

Anonymous

8:49 PM

Now that I look back...I didn't even read 30 percent of all those books thoroughly...before starting prep I used to feel like more the number of books the better marks you will get :P Alas! Time's too short.

John Doe

@Mithrandir24601 Are you familiar with the colored balls in boxes probability question?

Mithrandir24601

And I haven't even got 10 textbooks...

@JohnDoe Sounds like one of those things that there's loads of variations of, so it's possible...

John Doe

@Mithrandir24601 I have a proposed solution...

Mithrandir24601

What's the question first?

John Doe

@Mithrandir24601 You have two bags with two red balls in one and a red and blue in another. You randomly choose a bag and choose a red ball. What is the probability that the ball that remains is blue? That's the question. My solution is...

Anonymous

8:57 PM

That is just the probability of choosing the red ball in the other bag....

Transcript for