The h Bar

If you define a function of three variables in Python. In the definition of the function if you have a loop that writes to a file. Would the code write to this file for any value of the function executed?

Emilio Pisanty

ooooooh, I know what it was

Semiclassical

it's not what it was, no

Phase

@EmilioPisanty why the comment about "sharp decline in quality"?

Semiclassical

6:13 PM

I follow a few webcomics

lets see

Phase

Why is it worse now? :o

Curio

And m=mass g = gravity acceleration

Emilio Pisanty

there's people that are graduating uni who don't remember any pre-euro national currencies

Semiclassical

Sluggy Freelance, Dumbing of Age, Schlock Mercenary, SMBC, Sam and Fuzzy

John Rennie

It's that time of the evening where my armchair and a glass of beer are calling to me ...

Emilio Pisanty

6:14 PM

primarily aimed at the ~30-35 yo European demographic, that one

Semiclassical

XKCD is more occasional for me

Emilio Pisanty

@Phase early xkcd was way better than it is now

Semiclassical

the first three of those, though, I definitely check on a regular basis

oh, and Questionable Content

Phase

I mean if I was to go back and compare I'd probably come to the same conclusion, but only because I feel his delivery has gotten worse now

Emilio Pisanty

@Semiclassical Lego Grad Student not on that list?

Semiclassical

6:15 PM

nope. haven't seen that one

going to resist looking for the moment

Emilio Pisanty

@Semiclassical y'shouldn't

it's like PhD Comics before it ran out of ideas

and it's dark

Semiclassical

lol

i'll check it out eventually :P

ACuriousMind

@EmilioPisanty Well...at least he's beginning to understand where the problem lies :P

Emilio Pisanty

@ACuriousMind yeah, it's an improvement, for sure

Semiclassical

using the same symbol for different things...yikes

i guess you could understand it, though, as: "If we adopt X as our convention, then E means this. If we instead adopt Y as our convention, then E means this."

Emilio Pisanty

6:18 PM

@Semiclassical take it from us, it's a marked improvement

Phase

Damn.

Semiclassical

...on the other hand, that only really works if either X or Y are standard conventions.

@Phase ...

ACuriousMind

@Phase The hashtags are...troubling and amusing.

Semiclassical

get out

Phase

I wanna go into research

Emilio Pisanty

6:19 PM

Phase

this comic is deeply unsettling

Semiclassical

loool

that's pretty good

Emilio Pisanty

(just sayin')

Phase

ACuriousMind

@EmilioPisanty Well, I'm not sure how much I actually remember the Mark. I was nine when the Euro came, I don't think I cared about what the money's called back them.

Phase

6:21 PM

Oh no I'm one of them

Semiclassical

"Leading undergrads through a calculation he was never very good at when he was in their shoes, the grad student makes flagrant use of the printed solution."

Phase

I don't maliciously pass judgement, I'll just remark on one particular grad student's penchant for cargo shorts, socks and sandals

Emilio Pisanty

@Phase you'll be there soon enough ;-)

ACuriousMind

As a German, I don't see anything wrong with that outfit :P

Phase

You and your virtual lederhosen @ACuriousMind

ACuriousMind

6:22 PM

@Phase I'm not from Bavaria.

Phase

Close enough

Balarka Sen

why are we reading roblox cartoons

Emilio Pisanty

Phase

my geography knowledge is terrible even for my own country

Emilio Pisanty

kinda thing

Phase

6:22 PM

Im amazed i got so close

ACuriousMind

@Phase Well, I mean, Bavaria is part of Germany but it's a weird part and I have nothing to do with it :P

Phase

Dont be mean to the bavarians

They invented beer

probably

Emilio Pisanty

@Semiclassical see e.g. physics.stackexchange.com/questions/341326/…, but you can't see the deleted answers =|

Semiclassical

i'll take your word for it

John Doe

@EmilioPisanty Hi. Not sure if you remember this post. Could I ask, how does the experimenter go about carrying out the measurements given the different ways we can define the measurement operators?

Emilio Pisanty

6:26 PM

@JohnDoe by thinking carefully about the actual dynamics that occur in the specific experiment of interest.

0celo7

@ACuriousMind good.

My mom says people who Bavaria are jealous though

Not sure how true that is

ACuriousMind

@Phase I think the Czechs might have beated us to that, hence Pilsner :P

John Doe

@EmilioPisanty Give me an example that's a bit vague.

Emilio Pisanty

@0celo7 never seen Bavaria used as a verb

Calvin is right

ACuriousMind

@0celo7 You a verb there.

Emilio Pisanty

6:27 PM

verbing weirds language

0celo7

Huh

I meant hate Bavaria

Emilio Pisanty

Phase

Let that be a reminder never to Bavaria without checking your grammar

Emilio Pisanty

@JohnDoe the point is, it depends on the situation. Your question isn't specific enough to say anything more.

John Doe

@EmilioPisanty Okay I see thanks.

Balarka Sen

6:30 PM

In Soviet Russia, Siberia verbs you

Emilio Pisanty

@ACuriousMind can you double-check the signs here?

This is less wrong than your previous attempts, but it is still not right. It is correct that $(A_1,A_2,A_3)=-(A^1,A^2,A^3) $, but it is *not* correct that $\vec A$ as a three-vector has two different signs (which is plainly nonsense). Instead, the correspondence works as $A^\mu=(\phi,\vec A)$ and $A_\mu=(\phi,-\vec A)$ (setting $c=1$, with signature $+---$). — Emilio Pisanty 40 secs ago

Phase

@0celo7 @BalarkaSen dumb topology question but a square is four / infinite 1 dimensional lines [perimeter / actual solid surface], a cube is 6 / infinite 2D squares, Can you make a 4D shape using 8 cubes / any number of cubes?

Balarka Sen

Google tesseract

Emilio Pisanty

google hypercube

actually, no, just take a gander at this

What does VR reveal about the 4th dimension?

►

Phase

so... is it 8 cubes but with a fundamental limit on how many we can see at a time?

Like looking at a 2d projection of a cube

0celo7

6:38 PM

Party trick math

Semiclassical

suppose you use the sun to project the shadow of a 3D cube onto a 2D piece of paper. if you orient it right, you'll just see a square. in a similarly way I imagine you can get the 3D cube as the projection of a 4D hypercube

Phase

or is the sequence just not as neat as 4,6,8,10....

ACuriousMind

@EmilioPisanty I think that looks fine to me

Emilio Pisanty

@ACuriousMind cool

@Phase that depends on what you mean by that sequence

Semiclassical

(I'm saying to use the sun so that the light source is infinitely far away and all the light comes in parallel)

Emilio Pisanty

6:40 PM

@Phase but same as a 2-cube's boundary is four 1-cubes, and a 3-cube's boundary is six 2-cubes, a 4-cube's boundary is indeed eight 3-cubes,

Phase

@EmilioPisanty the number of lower dimensional versions of the object [cube family] it takes to compose the next one up

Emilio Pisanty

@Phase "takes to compose" is a terrible way to think of it

Phase

Idk what a 1-cube is. isn't that just a line?

Emilio Pisanty

yes

:41302802 dunno what you're talking about

(but thanks =P)

Semiclassical

how could you, there's nothing left that I said :P

peterh

6:42 PM

@Phase It is the 2D perspectives projection of a 3D tesseract, which is the 3d projection of a 4d cube.

Emilio Pisanty

@Phase just watch the damn video ;-)

Semiclassical

the tricky thing with the perspective analogy is that, if you project a cube onto a piece of paper, you won't usually get one square

CooperCape

Speaking of 1-cubes n' such (this is probably unrealted but whatevs just reminded me...) is a sphere 2 or 3 dimensional 'cause I've been annoying my maths friends by saying it's 2 dimensional and now I'm just confuzzled...

Emilio Pisanty

and if you have any access at all to a HTC Vive, or other such gear, I highly recommend you take a look at those apps

Semiclassical

indeed, the outline would be some six-sided polygon I think?

it's only when you line the cube up right that you'll get a square

Phase

6:43 PM

:( but videos are slow

peterh

Hehh... my spellchecker offered to fix "of" to "offtopic"... it seems today I've used the second a little bit more often

Semiclassical

offtopicten

though actually if we were to follow that to its logical end, you'd have

of->offtopic ->offtopicftopic -> offtopicftopicftopic ...

(logical is perhaps the wrong word there.)

Emilio Pisanty

@Phase 5:30 to 6:10 in particular

Phase

It's really frustrating to lack prereqs

grrrrr

0celo7

@Phase measure theory is the worst

Everything uses it but it’s pretty hard to learn

Emilio Pisanty

6:49 PM

@0celo7 what's so hard about measure theory?

you've got a measure $\mu$

you give it a set $S$

you get the set's measure $\mu(S)$

boom

done

Phase

I have a measure [$\mu]$

I have a set [$S$]

UGH

Set Measure [$\mu (S)$]

Emilio Pisanty

@Phase in case it wasn't clear, that was pretty sarcastic ;-)

Phase

I was making a pen pineapple apple pen reference

if you didnt get it its a good thing, it's a terrible meme

Emilio Pisanty

saying "I have a measure $\mu$" implicitly says "I have a measure $\mu:\mathcal A \to [0,\infty)$", where $\mathcal A$ is a sigma-algebra

and an understanding of what a sigma-algebra is

0celo7

No no no

You start with a sigma ring

And you want that interval to be closed at infinity.

Emilio Pisanty

6:52 PM

@0celo7 a what?

0celo7

It’s a sigma algebra but without complements.

Emilio Pisanty

what?

CooperCape

"You suck sigma algebra"

Emilio Pisanty

Sigma-ring

In mathematics, a nonempty collection of sets is called a σ-ring (pronounced sigma-ring) if it is closed under countable union and relative complementation. == Formal definition == Let R {\displaystyle {\mathcal {R}}} be a nonempty collection of sets. Then R {\displaystyle {\mathcal {R}}} is a σ-ring if: ⋃ n = 1 ...

CooperCape

That kind of without complements?

0celo7

6:54 PM

Yeah that’s relative complements. I mean that the whole set isn’t necessarily in the ring.

So A^c isn’t necessarily either.

Emilio Pisanty

> Let ${\mathcal {R}}$ be a nonempty collection of sets. Then ${\mathcal {R}}$ is a σ-ring if:

> 1. $\bigcup _{{n=1}}^{{\infty }}A_{{n}}\in {\mathcal {R}}$ if $A_{{n}}\in {\mathcal {R}}$ for all $n\in \mathbb {N} $
2. $A \setminus B \in \mathcal{R}$ if $A,B\in {\mathcal {R}}$

@0celo7 ah

0celo7

Yes. Now add X in R to that and you get a sigma algebra.

Emilio Pisanty

@0celo7 w/e

0celo7

Where X is the universe

Emilio Pisanty

I did a full semester of measure theory and they never mentioned sigma rings

can't've been that important

CooperCape

6:58 PM

inb4 Ocello makes a 'physicists don't appreciate maths properly' kind of reference...

0celo7

No, Emilio is too smart for that. He’d find some way to hurt me.

CooperCape

that sounds... ominous.

0celo7

@CooperCape He’s an ominous guy.

Phase

@0celo7 where does he fall on a BalarkaSen ------- Shog9 scale

0celo7

Lol is Balarka the least threatening person you could think of?

Phase

7:06 PM

In this room? He's not threatening

Who else would you have me pick, you?

0celo7

I am nonthreatening?

Phase

not at all

hence the italics

0celo7

I guess that’s good, but I’m also the insane American with 70 firearms.

Phase

I'm still not sure if you're gonna drive round to my house and shoot down the door

Just because I treat differentials like fractions

CooperCape

Ocelo once said 'jesus' to me... I was hurt, greatly.

Phase

7:08 PM

what a monster

0celo7

You think Jesus is a monster?

CooperCape

wait let me link the pain he put me through.

@0celo7 I mean to be fair I was being retarded af but whatevs.

dmckee

@Phase goodreads.com/quotes/…

> “Even the pious Scots, locked throughout history in a long-drawn-out battle with their arch-enemies the Scots, managed a few burnings to while away the long winter evenings.”

― Terry Pratchett, Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch

Phase

Come on @0celo7 he's like 16

0celo7

Who is

CooperCape

7:11 PM

I am 16...

Phase

@CooperCape

CooperCape

I don't think he knew

I'll put it down as fair.

Phase

@dmckee aha, I've never read pratchett, am I missing out?

tbh I dont know what $C^1$ is

CooperCape

I like how looking through Oceloooos messages for 'notation' the first thing that comes up is "USE BETTER NOTATION"

dmckee

@Phase Yes. Though that book is actually co-authored with Neil Gaiman.

Phase

7:15 PM

Oh

@EmilioPisanty w.r.t the stuff about cubes earlier

Would it be better to talk about vertices being doubled?

Emilio Pisanty

@Phase what? no

Phase

Since extending an object like a cube into another dimension seems to double the verti- oh :(

Semiclassical

eh, I think that actually works

dmckee

I am, of course, proud of my Scottish name and like to think that the streak of dour cantankerousness that runs in the family harkens back through the many generation since my father's line left that country.

Emilio Pisanty

I mean, maybe it's true

Semiclassical

7:17 PM

if you have a n-cube [0,1]^n and want to extend it to [0,1]^(n+1)

Phase

It goes 2 -> 4 -> 8 -?> 16...

Semiclassical

then you're going to take two copies of the [0,1]^n cube and connect all pairs of vertices

Phase

since when you extend a the cube you're basically making a copy of the shape / its vertices and seperating them

Emilio Pisanty

@Phase if by vertex you mean a single extremal point, then yes, an n-cube will have 2^n vertices

Semiclassical

so the two vertices labelled as (0,0,...0) in the two n-cubes become (0,0,...,0,0) and (0,0,...,0,1) respectively, and there's an edge between them

Emilio Pisanty

7:18 PM

but that downplays the wealth of different types of boundaries involved

i.e.

the 1-cube has two vertices

the 2-cube has four vertices and four edges

Phase

3 cube 8 and 6

whoops

read that as surface

Emilio Pisanty

the 3-cube has eight vertices, six faces, and twelve edges

Phase

for some reason

Semiclassical

it's also worth noting that there's a great deal of ways to get to 2^n vertices if you start with {0,1} x {0,1} x ... x {0,1} in this way

Emilio Pisanty

the 4-cube has 16 vertices, 8 3-faces, $x$ 2-faces, and $y$ edges

Semiclassical

7:20 PM

you can take the cartesian product of the first two, then product that with the third, etc.

Emilio Pisanty

The n-cube will have 'edges' of all dimensionalities between zero and n-1

Semiclassical

but you could also start with the last pair and go backwards, and so forth

you'd of course end with the same number of vertices

but the edges would be generated in very different orders.

Emilio Pisanty

i.e. as you go up in dimension you have more types of edges to count

Semiclassical

higher dimension means more possible dimensions of subsets

(though an edge is a bit more involved than just a subset)

Phase

Steam sale @0celo7

Ends on the 28th

So you shouldn't miss it

0celo7

7:28 PM

What games are good

Phase

Brother sister bathtub sim$^{tm}$.

Idk how would I know what games you like : P

CooperCape

Shower with your dad simulator

Phase

that one's a real masterpiece

Might get Siege, it's like £6

0celo7

@Phase @CooperCape those seem very inappropriate.

Phase

I dont actually know what games to get

I feel dispassionate, have done for the past few weeks, hoping it'll pass soon. Any recommendations for games @0celo7 @CooperCape ?

CooperCape

7:37 PM

ocelo hitting us up with the inapropriate

tbf shower with your dad is humerous if not a little weird

Ummm idk.

I don't play a lot

Used to play a lot of runescpae tho ;p

Phase

Guess I'll pick up Tyranny because its like 10 quid and @ACuriousMind would kill me if I didn't

0celo7

Ass creed O was great

Phase

@0celo7 Dont think I can run it to a point where I'll be happy on this

Its so poorly optimised

even on low

0celo7

Yeah it did melt my computer

Phase

think ill pick up Styx

looks like a fairly fun stealth game

maybe not, ugh.. decisions

witcher 3 is for 12 quid what a bargain

I'll keep some cash leftover so @0celo7 if you decide on a game thats on sale that has MP [and isnt trash], lemme know

0celo7

7:58 PM

BF2

Phase

You're being sarcastic right

wait which one

Anonymous

How do we prove the principle of virtual work from the principle of least action?

Phase

@Blue like this

Anonymous

@Phase Physics is more fun than sex ;)

Phase

Why not both

at the same time

Anonymous

8:08 PM

Why spend time on something less fun ? :P

Anonymous

Oh, lol. I see what you mean

Anonymous

Sorry, I don't have a partitioned brain. I can focus on only one thing at once

Sid

I don't vouch for blue's words. I have only tried one of the two things mentioned. :P

Anonymous

Reminds me of what an old wise man once said:

Anonymous

Mar 8 at 17:11, by Ben Niehoff

I think it's a bit like becoming a monk

0celo7

8:12 PM

Oh Jesus Christ the string theorist in my rep theory class is unbearable

CooperCape

does he not respecc the maths

Sid

Oh, I think I missed my Calling. Congrats @ACuriousMind

0celo7

@CooperCape he says stupid stuff

CooperCape

Uh huh...

I feel like your stupid is most certainly not my stupid so I decline to comment.

Anonymous

This is probably the first time I'm seeing so much excitement in a teacher:

Anonymous

8:21 PM

Jordan Canonical Form

►

Anonymous

In the first 1 min or so XD

Anonymous

Lol...heard that wrong

Mr. Xcoder

@Blue WTH does he have 5 blackboards?!

Anonymous

But whateva...he's just too excited :D

Sid

@Mr.Xcoder Perhaps, he writes too much. We don't have time to waste by erasing the writings in the blackboards! :P

Anonymous

8:23 PM

@Mr.Xcoder Because he doesn't not have 5 blackboards

Mr. Xcoder

.... He does

Anonymous

Well, the reason is what Sid mentioned

Mr. Xcoder

Anonymous

@Mr.Xcoder I did notice all the 5 boards

Phase

I think being in the same class as @0celo7 would actually be a personal hell of mine

Anonymous

8:26 PM

Notice my sentence again:

Anonymous

2 mins ago, by Blue

@Mr.Xcoder Because he doesn't not have 5 blackboards

Phase

"Hey @0celo7 what did you do for this? I cant think what to do for it"
"It's trivial you [redacted] pleb"

Mr. Xcoder

@Blue doesn't not ... ಠ_ಠ

Anonymous

lol

Phase

someone save me from myself

I'm hooked on SMBC

0celo7

8:37 PM

@Phase I think math is very hard

So that doesn’t sound like something I would say

Phase

Yeah but you're also very good at maths, and your idea of hard maths =/= another person's. If you saw me struggling irl with maths you found easy, I can't help but imagine you being frustrated : p

@0celo7 smbc-comics.com/comic/2013-10-24

Sha Vuklia

Guys. My book says the following: “To compute the entropy over long time scales, we should compute $\Omega_{\text{total}}$ by summing over all macrostates for the two systems.” I don’t really understand what they mean by “entropy over long time scales”. Why do they have to mention the time scale? Even over long time scales, the system will tend to the state of greatest entropy, so why would a large time scale enable us to talk about all possible microstates?

we're assuming here two systems that can interact, btw

Anonymous

8:53 PM

Time average of entropy

Anonymous

Over greater time, you get more accurate results

Anonymous

@ShaVuklia Wait, then that is confusing

Emilio Pisanty

Made this for a friend and it's too good to keep in a drawer:

don't ask me what it is, though, I probably shouldn't tell =P

CooperCape

it's like a groovy ass vector field

did he ask you to make 'one groovy ass vector field'?

Emilio Pisanty

pretty much ;-)

Anonymous

9:03 PM

Oh, I see. They are talking about long-term entropy here

CooperCape

That's a cool

description

Anonymous

Actually over long time scales all possible microstates can be assumed to be attained by the system. So you define $S_{long}$ as $k\ln(\sum\Omega)$

Anonymous

@ShaVuklia So, from what I understand, they are trying to say that over long time scales all possible microstates are attained by the system. Hence they are introducing a notion of long term entropy. (Summing over all the states)

Phase

That's a really really weird effect

What even is the curl of that field

@EmilioPisanty

It's like a periodic curl

spooky

Anonymous

This book discusses long term entropy in brief

Anonymous

9:16 PM

And no, entropy does not always increase with time

Anonymous

That's a misconception

Anonymous

It just that a system in equilibrium is found in the state with greatest entropy

Sid

9:34 PM

Lol. I just found this funny proof that says about proving that the cube root of 2 is irrational

Balarka Sen

fermat's last theorem?

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