00:00 - 16:0016:00 - 00:00

12:05 AM
@enumaris if you end up continuing with the music recommendation idea, you may find some interest in this listenbrainz.org

unfortunately, with no software engineer in sight, I'm pretty stuck lol
What's the actual data though? I don't want to access it right now.
music listening histories of a bunch of users?

Yeah I believe that's what it is. It has a way to query it on bigquery or download a dumb of the data

I see, nice nice
that's actually really helpful to that project :D
The data I was working on for that project came from 2011 so it was kinda dated...

Looks like the data dump is only 5G if I'm looking at the right thing
Speaking of music, Ice Cube's new album is surprisingly good (at least if that's your taste in music)

the data I worked on had a lot of features for a lot of the songs, not just playlists though
so it was 300gb

12:27 AM
Depending on the type of features you're talking about, acoustibrainz or musicbrainz may have it. Musicbrainz has all the artist/album/genre and similar info. Acoustibrainz has something to do with recognizing a song, so I guess they have clips or something. I'm not too familiar with that

the features were actually quite close to audio features
timbre, pitch, loudness at each segment
I built a content-based recommender system based off that...
my loss was top 15 compared to the kagglers that used that data set back in 2011 lol...but I think few of them used content based systems
but then...software eng ghosted so I haven't looked at that in a while...
kinda busy applying and interviewing right now lol
the 3D rendering idea appeals to me a bit more right now

Yeah the rendering direction is quite interesting

4 hours later…
4:59 AM
@Blue Having coded in fortran 77 for years I would characterize it as clunky, and missing a few useful feature but not as anything approaching the horror of a real bad language.
It's reasonable regular, reasonable well specified, and has few surprises. It just doesn't have any great features except those tens of millions of well debugged lines of libraries.
I wouldn't go out of my way to code it it, and don't like having to deal with legacy code bases written in it, but it wouldn't be anywhere near to the top of my "Please, anything but that! I'll tell, I'll tell you everything!" list.
@Blue n my current situation my computer is running windows. But I'm developing on a linux VM.

5:20 AM
@dmckee Umm, what's the advantage of using a Linux VM on Windows rather than going full Linux?
@dmckee Well, I wasn't expecting it on the top of the "dreaded" list :P But it's a bit surprising that Fortran is not mentioned anywhere - neither in the "loved" nor in the "dreaded" list
Maybe it's just - out of date
@dmckee Yes, I did hear that Fortran has some great libraries for numerical computations

@Blue for everyday stuff Windows or OSX are easier simply because there is so much support for them. Remember how we couldn't get the WiFi on your laptop working in Linux. In Win/OSX that is rarely an issue.

1 hour later…
6:50 AM
HATS
I found a hat.
@dmckee HATS
@ACuriousMind perhaps you've heard of hats.

7:27 AM
Is it hats season again

Hats are upon us!

1 hour later…
8:29 AM
only 16 C now, the lowest temperature since the summer

@CaptainBohemian whereabouts in the world? In my part of the UK we've had several nights already where the temperature dipped below zero.

9:01 AM
I guess I should try to answer some questions
Get me a hat

1 hour later…
10:02 AM
0

It is obvious that Physics SE community aren't here to solve specific physics problems. Homework policy, however, states that a question can be narrowed down to a conceptual question. To reinforce what has been said, As a general rule, we do not discourage homework questions, as long as they...

2 hours later…
12:15 PM
@Slereah Nah, you get one for not visiting the sites too ...

@TheDarkSide too late
I visited the site!
"Team Player
visit the Stack Overflow for Teams landing page at stackoverflow.com/teams"
I visited
where's my bloody hat

Might take a little while for SE to pull it out of the hat-reservoir maybe.
No, I was referring to: "Still Fresh: be a user on the site for less than 6 months before Winter Bash, or join during Winter Bash; have earned at least 25 reputation"
This is an amusing criterion.

Still no hat
Time to begin the revolution

@TheDarkSide I'm gonna need some help parsing this image
I need some Sobolev help

12:36 PM
Check out this guy: the SE-wide hat leader. Some nice hats.

12:48 PM
@TheDarkSide Why would it be amusing?

@ACuriousMind you around?

@Blue I met that 25 rep criterion via association bonus, so that's hardly a criterion then. Anyways, good if everyone has a hat. That's how you suck people into this hat business.

@TheDarkSide Oh. I didn't know association bonus counts. :)

Hehe. BTW, good that your avatar appears blue too. :P
@Slereah Here's the "reason":
6

Team Player is one of two hats being awarded from our Events database, part of our internal analytics system. I'm not sure how everything works, but there's queues and batches involved so there can be a substantial delay between when you visit the page and when you get the hat. (As a dev, it ca...

Give me the hat or the bunny gets it

1:01 PM
LOL

It would be fun if they allowed us to borrow and share hats :D

@JohnRennie Another round of Tory backstabbing on the way?
Has May resigned?

@Sid no.
She will win the no confidence motion so there is no danger of her being forced to resign. Well, not just yet.

did you try going to the streets and putting everything on fire
such is the French way

1:12 PM
@JohnRennie the threshold is 158, right? Does she have that much support?

@Sid most conservative MPs do not want a leadership election right now. It would probably trigger a no confidence motion from the opposition and the government stand a real chance of losing it.
That would force an election that could do a lot of damage to the conservatives.

Damage the conservatives I say

Why was there a No-confidence motion anyway?
Because of the horrible way the negotiations in Brexit are going on?

47

Here we go again the Winter Bash is here and the hats are listed below. The list has the same format as always, there are only two answers: one for the secret hats, and one for the regular hats. The secret hat list will be updated as we learn them. Only edit the secret hat answer with definitiv...

@Slereah You can get the Retro Fan hat easily ^ :P

I just tried and apparently not!
I guess there's a delay too

1:24 PM
Yeah, I think there's a script that runs every couple hours or so

Or at least similar ones.

He said, wearing his specs

Lol

probably 6 to 8 something — rene 4 mins ago
^ Cracked me up.

Seconds? Days? Years?

1:25 PM
Exactly.

It's a running SO meme

@Blue Yeah. I had upvoted that some time way back, but had forgotten that ever since. That's why it cracked me up at that reference.

Finally found the Good Theorem
So that QM isn't nonsense
The nuclear spectral theorem

@Slereah I wonder how much of the nonsense about quantum mechanics being "spooky" is a semi-conscious reaction to the double meaning of "spectral."

$$\forall \phi, \psi \in \Phi, \langle \phi, \psi \rangle = \int \xi_\lambda(\psi) \overline{\xi_\lambda(\psi)} d\mu(\lambda)$$

1:40 PM
I know a guy who has an SE hat, in this season of hats. Hello Mr. @rob

that's the good stuff
Where $\xi_\lambda$ are the generalized eigenvectors of some self-adjoint operator $A$ such that $A^\times \xi_\lambda(\phi) = \lambda \xi_\lambda (\phi)$
It's the fancy theorem for $$\langle \phi, \psi \rangle = \int \langle \phi, p \rangle \langle p, \psi \rangle dp$$
Finally for my specs
got*
" The proof in Gelfand's Generalized Function vol 4 is incorrect (at least not complete), as pointed out by the translator of the English version."
shakes fist

1:56 PM
Hey, you got the hat. So it takes ~1 hour :)
Or maybe 30 mins

doing theoretical physics is a bit of a weird thing
It's like
Whenever I meet other physicists
And I show them what I'm reading or working on
It's like WHAT THE FUCK IS THIS
like it's not even within the realm of topics they could read
If it's not calculus and linear algebra that is already TOO FAR
though on the flipside
The situation is reversed talking to math people
Forever torn between two worlds!

2:12 PM
@Slereah too much math for physics and too much physics for math
pet peeve: author notes in passing that their theorem can be modified in a certain way, but doesn't explain why that's equivalent.
plenty of detail is provided on the rest, but he seemingly makes that one remark without comment arghh

2:28 PM
@Semiclassical more like not enough math for math

yeah, i guess

I like doing proofs and all but doing like a full proper proof is a bit uuuugh
Partly because I don't have enough math culture to automatically know all the relevant theorems needed

guys, I feel a bit confused about this part. I don’t really see why the thermodynamically stable state is a combination of gas and liquid (at the transition pressure). I don’t really understand what the shaded regions mean.. and how is there in the shaded region always another state with a lower Gibbs free energy? where can I see that?

I wouldn't focus on the shading at first. instead, what you should consider are the following two trajectories: either the one shown (1,2,3,4,5,6,7) or the mixing path (1,2,4,6,7)
the main point is that having a mixture of gas/liquid at the transition pressure amounts to staying at the point 2=6 in the G vs. P graph

yea, because if you were to choose one state over the other, the other state would have lower G energy. but how is this other state then not the stable state? from a naive pov, it seems almost contradictory to me. also, I don't really understand why the mixing path doesn't include 3 and 5?..

2:42 PM
because that would mean that you're changing the pressure. (re: 3 and 5)
one thing which I said wrong above, though:
I indicated that the mixing path would be 2,4,6
but if you look at 4, it's shown in the first figure as having higher pressure
so that can't be right.

it has the same pressure right? just higher G

the point is really that a point on the PV graph doesn't map onto a point on the GV graph unless you further specify the composition
point is that the mixing 2->6 occurs at the transition pressure

yea, but I don't see why the shaded region would be unstable, while the rest in stable. it has to do with the G energies, but I don't see how
"there is always another state at the same P with a lower G energy", that seems to indicate to me that we could just choose that state then? but I'm guessing we don't get the volume right then?

the weird thing is, again, how the graph on the right tracks the one on the left

hm, well, I do understand that the curve 2-3-4-5-6 is unstable, but I'm confused about the region in between i guess?

2:48 PM
Suppose you were to continuously vary the volume of your van der Walls fluid, going from high to low

are we assuming that we want to stay on the coexistence line?

if you don't mix, then you'll simply follow the path 1234567 and you'd get the G,P trajectory shown
right now I"m pretending coexistence doesn't happen

oh right, because the different phases will technically be a result from this argument

on the other hand, if you go from 1->2, move along the coexistence line, and then go from 6->7, what trajectory will you get in the GP plane?
right. so as you vary the volume along the coexistence line, you won't move in the GP plane

oh i thought i was wrong

2:51 PM
lol

@Slereah that's why you aim for the TP math dept

@Semiclassical yes, this makes sense, because it's practically impossible
so your pressure has to stay the same
during that trajectory
okay, well I do see the contradiction that if there was one state, then this state would have to "stay", otherwise we would have a state transition, and then the problem would lie at that point

so the upshot is that the way to minimize the gibbs free energy throughout is for G to stop changing once you reach the coexistence line, and only start increasing again upon moving beyond it

@Slereah and have someone else eat the damage from brexit?
no, man, let them own that mess
then let someone else fix it

the significance of the shaded regions is that they're equal, and this is what defines the coexistence line

2:55 PM
but why would Labour step in to hold the ticking time bomb when the timer is a few seconds away from blowing up?

well I got that, because we want $\Delta G=0$

in other news, though
are hats live in PSE yet?

$\hat{PSE}$

I want a pizza hat for my torus knot
@Semiclassical I guess like all Winter Bash hats, that fits pretty badly

yeah

2:56 PM
$\widehat{\rm PSE}$

better

hmmm

but just one last try

$\widehat{\rm HousE}$

the unshaded regions represent stable states

2:57 PM
?
no, that doesn't do much

while the shaded regions represent a mixture, since one state can never be stable

$\widehat{|\ °\rm n \ |}$

I'm still confused about the sentence "there is always another state with lower G". how doesn't that mean that we could choose that state then? we want to minimise G after all

the trajectories are what define the states. the points in the shaded region aren't states.

$\widehat{|° \: \Pi \:|}$

2:58 PM
$$\widehat{|\: ^\Box\rm \Pi \:|}$$

well I would think that the trajectory 2-3-4-5-6 doesn't exist, but why the stuff in between as well?

Because that's not what the van der Waals equation of state dictates

$$\overset{\ \xi}{\widehat{|\: ^\Box\rm \Pi \:|}}$$
3

but it's possible to have a state in the non-shaded region, right?

What?

3:00 PM
a point in the white region, can that "exist"?

If you change the temperature, sure.

$$\overset{\ \overset{\xi}{\sqcap}}{\widehat{|\: ^\Box\rm \Pi \:|}}$$

'Question: What is the difference between theoretical physics and mathematical physics?

Answer: Theoretical physics is done by physicists who lack the necessary skills to do real experiments; mathematical physics is done by mathematicians who lack the necessary skills to do real mathematics.'
4

oh right, I interpreted it as a phase diagram:p

But you're not changing the temperature. You're holding that fixed and varying the volume.

3:01 PM
It's a chimney

0

Question: What is the difference between theoretical physics and mathematical physics? Answer: Theoretical physics is done by physicists who lack the necessary skills to do real experiments; mathematical physics is done by mathematicians who lack the necessary skills to do real mathematic...

right

@bolbteppa Destroyed

so the white space is what we can't enter, and the shaded region for some reason is a mixture

Well, remember that you're considering two options. One is that the entire fluid is in the same state. The other is that it's in a mixture of states.

3:02 PM
so technically you can vary the pressures then? that's why it's a region?

No. The fact that it's a shaded region is simply to reflect that $\Delta G=0$

it just depends on which state you have more?
oh wait!!
I think I get my confusion
and the shaded region is just for $\Delta G=0$

I wouldn't quite say it encloses the shaded region
You need both it and the coexistence line for that

yea with the straight line
isn't the curve the coexistence line?
or is the straight line the coexistence line?

The coexistence line is the line segment.
Since it's the line you get when you allow a heterogenous mixture of gas/liquid

3:07 PM
rightrighright
whoaw okay, this was pure misinterpretation from my part
many many thanks, semi

honestly, when you decide to help me, I know I'll most likely get it:p

part of the point iirc is this: by allowing a mixture of the two states, the increase in the pressure of one state is counterbalanced by the decrease in pressure of the other state

@bolbteppa boy, that needs to be deleted.

since the pressure should be the sum of the partial pressures

3:10 PM
@EmilioPisanty boo

I'd have to work through the details for that tho
@EmilioPisanty That seems like the kind of answer that would have worked just as well as a comment

as a comment?
ah
like, it's kinda true, but not the real full answer we're looking for...?

I mean, one could use that joke as a jumping off point for a more detailed answer

right yea

"it's a joke" $\implies$ "it's not an answer". This needs to be deleted. — Emilio Pisanty 2 mins ago

3:12 PM
But as it stands it's not an answer; it's a commentary on the question

what else can I say

yea, it's good for intuition/visualisation i think

@ShaVuklia It's not.

It's the best answer to this question

It's good for pretending to impart understanding while simultaneously obscuring the actual differences involved.

3:13 PM
@ShaVuklia was that in response to the thermo stuff, or for the theoretical/mathematical physics stuff

It's good for Class of People 1 to feel smug about being snarky about Class of People 2.

it was in response to your comment about pressure and mixtures, so thermo yea:d

@ShaVuklia ah, good.

I think it can also read as self-deprecating humor

3:15 PM
but, it all hinges on the "self-" part of that

@Semiclassical was Mermin a mathematician? unless he was, it doesn't read as such.
regardless of who the person quoting it is.

Ethel Merman (16 janvier 1908 à New York - 15 février 1984 à New York), est une chanteuse et actrice américaine de Broadway, interprète de films musicaux. Elle était reconnue pour sa voix exquise et portante, son style de chant théâtral, ses manières extravagantes et ses rôles qui pour la plupart du temps sont des femmes explosant d’assurance et possédant un cœur d’or. == Biographie == === Ses débuts === Ethel Merman est née Ethel Agnes Zimmermann. Elle est la fille d'Edward Zimmermann, un comptable et pianiste amateur, et d'Agnes Gardner Zimmermann, une institutrice. Ethel débute dans la chanson...

eh, not a mathematician. but I could see him being placed in the realm of theoretical physicist
As a commentary on how physics/math sometimes view theoretical/mathematical physics, I think it's a relevant quotation

@Semiclassical so... not a self-deprecating comment, then

"Henceforth, by 1 foot we shall mean the distance light travels in a nanosecond. A foot, if you will, is a light nanosecond (and a nanosecond, even more nicely, can be viewed as a light foot). …If it offends you to redefine the foot … then you may define 0.299792458 meters to be 1 phoot, and think "phoot" (conveniently evocative of the Greek φωτος, "light") whenever you read "foot"."

3:17 PM
@EmilioPisanty well, that joke seems as much aimed at theoretical physicists as mathematical physicists

"This adaptation of a physical unit is one of several ploys that Mermin uses to draw students into space-time geometry. "
A crafty man

As a commentary on how physics/math sometimes views theoretical/mathematical physics, I think it's a relevant quotation. But that's not an answer by itself.

"I am awaiting the day when people remember the fact that discovery does not work by deciding what you want and then discovering it."
He is apparently very quotable

aaaaaanyways
December 12
excellent date to start Christmas stuff
Guadalupe-Reyes Marathon is a concept typical of Mexican culture. It began in the decade of the 1990s and informally refers to the vacational period from December 12 (Day of the Virgin of Guadalupe) to January 6 (Day of the Three Wise Men or "Tres Reyes Magos"). During this period there are several holidays which, linked together, create a "marathon" of festivities. During this period, the challenge is not only to attend the festivities but to at least drink any type of alcoholic beverage every day. This Marathon is not part of the Mexican Folklore; it is merely a pop-culture activity. The ...

I actually met Mermin when he visited campus a few years back for the annual public lecture. think he was talking about quantum computing? not sure

3:19 PM
> the challenge is not only to attend the festivities but to at least drink any type of alcoholic beverage every day
that's an imperfect rendition of the Marathon, though
there needs to be excess involved

(and the silly QM foundations project I've got has an old Mermin paper as context)

QM foundation is one of those things that seem important to the science enthusiasts but I'm not 100% sure it's really that important
I mean it's neat and interesting, but as far as actual problems go

yeah
i mean, I have a certain sympathy/fondness for the pilot wave interpretation
but it's hard for me to find much productive in it
(I feel like it has to be useful for something, but i'd be lying if I claimed to have solid examples)

@Semiclassical there are some attempts to use Bohmian trajectories to explain optical tunnelling ionization
I've yet to find them useful, but they're there

3:35 PM
yeah
I know there's some people in quantum chemistry who want to do that kind of thing

Since I don't really care about experiments I don't even care all that much about Copenhagen
No need to measure those wavefunctions

mostly I like pilot wave since it gives a visualizable story. it's not the same story you'd tell in classical mechanics---for instance, even things as simple as the principle of inertia can't be counted on---but it's still a story playing out in spacetime
but I'm not sure how much value that story brings, and there's definitely costs you have to pay for it

QFT is almost 100% without a care about measurement
At least the stuff I've seen
they use it ONCE for scattering formulas and then never again

yeah

which is unfortunate but then again I guess it's hard to say QFT things about non-scattering experiment
Hard to do like measurements of bound states without writing a whole book about it

3:47 PM
QFT is also so wrapped up in second quantization formalism

Well it's all tied up together
Anything not scattering/second quantization/foch space related is so awful that it's not worth getting into for a QFT book
it has to be its own book

hard to argue with that

(That is how you get GLIMM AND JAFFE)

One thing I did find myself curious about a while back was how the pilot wave interpretation makes sense of the path integral formalism
and it's sorta weird.
i had been planning to type something up about it, but it was too confusing for me to want to spend a lot of effort

could be worse, though
Like when you get into the less popular interpretations
That is when it gets weird

3:52 PM
lol
transactional interpretation

Like the sub-Copenhagen/MW/Pilot wave stuff
Transactional's pretty weird yeah
It's also the first one to ever talk about

I have a hard time taking many-worlds seriously

THE GUN EXPERIMENT
which I approve of
i wonder if Feynman read some sci fi stuff about the grandfather paradox and got the idea
but he thought "I can't just write it like that"
"It wouldn't be very rigorous"

Whereas I can respect the Copenhagen interpretation for saying "stick to stuff we can talk about experimentally"

I like the BST interpretation but it basically doesn't exist
it's like non-Hausdorff spacetime $\to$ ??? $\to$ QM interpretation

3:55 PM
I ultimately don't think that's a sufficient approach, but I can respect them wanting to make progress on the experimental stuff

People write papers about it once in a while
They write some topology stuff about spacetime
And go "Maybe it's useful for QM???"
and then never try it for QM
Also I hope the ER = EPR business will lead to something maybe
it would be cool

it's like the old Wheeler/Penrose vague ideas on the topic
yeah

my personal dream would be to somehow link stuff from exact WKB / resurgence theory to pilot wave theory

I still need to learn AdS/CFT properly first

3:59 PM
haven't seen any reason for that to actually work but I still want it to :P

00:00 - 16:0016:00 - 00:00