The h Bar

12:31 AM

@0celo7 I think this is of interest to you, no?

12:42 AM

@loltospoon Not having a built-in notion of matricies does not mean "can't do matricies", though it implies some hoops to jump through. And in the case of a language like c, you need to be deeply familiar with the hoops before you can chose the most appropriate manner and order for the jumping.

0celo7

1:54 AM

@Slereah link?

Slereah

Electromagnetic mass

Electromagnetic mass was initially a concept of classical mechanics, denoting as to how much the electromagnetic field, or the self-energy, is contributing to the mass of charged particles. It was first derived by J. J. Thomson in 1881 and was for some time also considered as a dynamical explanation of inertial mass per se. Today, the relation of mass, momentum, velocity and all forms of energy, including electromagnetic energy, is analyzed on the basis of Albert Einstein's special relativity and mass–energy equivalence. As to the cause of mass of elementary particles, the Higgs mechanism in the...

that kind of stuff

heather

::smacks code::

0celo7

@heather ::smacks heather::

no violence

dmckee

@heather I find that with me the Problem-Exists-Between-Keyboard-And-Chair very nearly every time.

Dang machine insists on doing what I tell it to do, instead of what I mean for it to do.

0celo7

@yuggib Suppose we have an unbounded op $A$ on $\mathscr H$. I specifically want it noncompact, else this question is trivial. If it's self-adjoint, we can use the spectral theorem to write it as an integral wrt. a projection valued measure. I understand that and have an idea of the proof (from Hall's QM for mathematicians book). But when do we have a discrete spectrum, and if we do, does the spectral theorem give a resolution of the identity?

I know that certain Hamiltonians have this property, it depends on the growth of the potential. I think it's in Vol 4 of R-S, it's mentioned in Hall.

heather

2:04 AM

@dmckee yep - just found the error and it was me being idiotic =)

vzn

@heather what are you working on?

in theory salon, 9 mins ago, by vzn

IBM will sell 50-qubit universal quantum computer “in the next few years” / arstechnica

in theory salon, 8 mins ago, by vzn

Machine Learning Is Bringing the Cosmos Into Focus / Atlantic

heather

@vzn hey, I noticed that =)

@vzn simulator of an ideal quantum computer

if you want to play with it (and tell me what's broken =P) use this link: repl.it/GD0M/42

oh, hey, it's revision 42

vzn

so did you tell your family about your chat session? btw wondering do you have brothers or sisters?

@heather seems very ambitous esp before finishing factoring :P

heather

@vzn no brothers or sisters, no

my mom read through the chat session though =) she thought it was pretty cool

@vzn yeah, I actually feel pretty close though!

vzn

nice. hey saw awhile back in transcript, what was name of that installer that allows putting ubuntu on a chromebook? was it hard? nice hack...

heather

2:15 AM

speaking of that factoring code, I'm gonna pull that up, because i've been staring at the other program since I got home from school, basically =)

0celo7

@Slereah are you still working on O'Neill?

heather

@vzn crouton, I believe...i updated my chromebook w/o thinking though and now I need to reinstall it or something, though - when I run it and try to start a session, I just get a black screen. (That's why I'm using repl.it not github.)

Slereah

yeah

heather

@vzn and no, wasn't hard - I followed some instructions on a website and I had the help of Daniel and Bernardo. I wouldn't really call it a hack at all.

0celo7

@Slereah what proof are you on?

vzn

2:17 AM

@heather ooh thats killer are you saying the chrome update kills the ubuntu distribution somehow? yeeks o_O ... hope you dont lose any data :o

0celo7

@Slereah Oh, I was reading some dissertations from people at my school, and one guy claimed his MS thesis was on Lorentzian metrics

in particular, the iff condition

Slereah

neat

iff condition?

0celo7

he said he found a simple proof for it

@Slereah iff you have a nondegenerate vector field

heather

@vzn I dunno what exactly happened, but I won't lose any data - all of it was github stuff anyway (downloaded repositories) and that's all saved, so.

Slereah

oh

Do you know the name of his thesis?

0celo7

2:19 AM

@Slereah Nope! I'm thinking about emailing him.

Secret

> A closed question will rarely be reopened in non PSE, MSE, CSE, WSE sites. Therefore if it closed, it is practically gone, and all effort to edit it is useless

vzn

@heather let me know if you need help with the factoring would like to see you veni, vidi, vinci :)

0celo7

what does that mean?

vzn

@0celo7 lol try dictionary &/or google mr smartypants... actually am thinking maybe a rapper refd it... pitbull? :P

0celo7

:(

Secret

2:20 AM

It's really like a CV. One wrong impression and you are out

heather

@vzn sure =)

thanks

vzn

@0celo7 metrolyrics.com/fireball-lyrics-pitbull.html

what?

what?

I don't like rap

2:23 AM

lol yeah just like youre not a nihilist :P

0celo7

I'm not a nihilist

and you'd better stop saying that or we're gonna have a talk

Secret

I'm also not a nihilist, because to me nothingness has a metaphysical existence as an object or noumenon

Put it simply, it is some kind of "stuff"

vzn

right, ~~rap loving nihilist~~ ~~nihilist loving rapper~~

heather

looking up the definition, I'm definitely not a nihilist myself

Secret

so is nonexistence

0celo7

2:26 AM

@heather pls you're 8

Secret

to me, every concept that you can feel or has a word for it, is metaphysical stuff

0celo7

you don't have a philosophy yet

heather

@0celo7 er...14. but sure.

vzn

@0celo7 a talk with 0celo7? more like a chat :P

Secret

Therefore, everything exists

0celo7

2:26 AM

@heather 8 = 14 mod 2.

heather

uh...14 mod 2 is 0

0celo7

and 8 mod 2 is also zero

see, you can't even divide

heather

::facepalms::

just ignore me

0celo7

@heather what's my motivation for doing this lab report

heather

@0celo7 you want to get a good grade? because it interests you? because it is fun?

all of the above?

0celo7

2:34 AM

The first, possibly. But I'm not sure if doing poorly on one lab report will affect my grade.

heather

because you want to feel productive?

0celo7

I'm reading functional analysis

that's productive

Secret

@0celo7 Well, for my uni, lab reports can cost 30-50% of the grade

0celo7

@Secret one lab report?

it'd be like 3% of my overall grade

heather

hmm...

because you don't want to be ashamed/embarrassed when you cannot turn in your homework (due to it not being completed)?

Secret

2:40 AM

@0celo7 uh, maybe not just one, but 10 of them in total (at least for chemistry). But some long ones do have higher % than others and can go up to 10%. I recall my microbiology class lab component has a weighting of 50% and if you fail at it, you fail the course

0celo7

@heather cute

heather

@0celo7 hey, I don't know. You asked.

Secret

Chemistry generally have 30% weighting, but they have an extra criteria that if you fail the lab component, you fail the course

so either way, if you fail the lab component, you fail the course in my uni

0celo7

I'm not about to fail the lab component

But I really don't want to do this

heather

@0celo7 okay, I've got a reason.

Because you paid for college and you might as well do the work you paid for.

0celo7

2:48 AM

You're really paying for the degree.

Some classes are just plain useless for what you actually want to do.

heather

hmm, fair enough.

well, if you're not interested, you're not paying for it, it won't affect your grade/future, and you don't mind the consequences of not getting your homework done, well...I'm not sure I could come up with another reason to do it.

0celo7

so you're telling me I shouldn't do it?

heather

@vzn, I think I may be halfway there with some new code I wrote (I rewrote the whole program)

@0celo7 no. I'm saying if all the answers you gave me are true, I personally cannot think of a reason to do it.

0celo7

@heather ok genius girl how do I fix my softcover books' covers from bending

vzn

3:14 AM

(@#%& battery dead + apple keyboard failed...) anyway 0celo7, re the theme, note there are a lot of nihilistic rappers & nihilistic rap lyrics... o_O

OBE

sup

0celo7

@vzn like?

eminem doesn't count, he tries to be edgy

vzn

awww geez was relying on you to help out here, am sure youre way more familiar lol. ruling out eminem? gimme a break... he was/ is edgy

0celo7

eminem did a verse on Big Sean's album a month ago and it was pretty cringey

I think he talked about period blood or something. Nasty.

vzn

hey, even rock has a lot of nihilistic lyrics! its an unavoidable part of youthful music... metrolyrics.com/bohemian-rhapsody-lyrics-queen.html

0celo7

3:20 AM

rock is for old men

vzn

can find just about anything on the internet, this from just a few mos ago :P reddit.com/r/hiphop101/comments/563n41/…

holy cow 29p academic paper, perfect for you to refute your assertion :P “I SEE DEATH AROUND THE CORNER”: NIHILISM IN RAP MUSIC1 / Kubrin

@heather rewrites can be good. however instead of typing, maybe youre now ready to learn debugging, young padwan :P

0celo7

3:37 AM

@BalarkaSen Complex analysis: Let $R(\zeta)$ be an operator valued function defined on $B\subset\Bbb C$ (some open disk). Suppose I have an isolated singularity at $\zeta_0$. I know that $R$ is analytic on $B-\{\zeta_0\}$. It's claimed that for $\zeta\ne \zeta_0$, the principal part of the Laurent series converges. I'm not sure what the principal part has to do with anything, the series itself should converge in closed annuli $\mathrm{ann}(\zeta_0,r_1,r_2)$, where I can make $r_1$ as small...

as I want, but still positive, and $r_2$ is small enough so that the ball $B_{\zeta_0}(r_2)\subset B$.

Does that sound right? I think they're just emphasizing that the principal part is what's interesting operator-theory wise. The convergence should apply the whole thing.

0celo7

3:49 AM

The convergence should be absolute, so removing part of the series doesn't change anything.

dmckee

I got to use the phrase "plastic-bottle schrapnel" in a communication to students today.

Because people post some really stupid stuff on youtube.

0celo7

@dmckee sounds exciting!

dmckee

@0celo7 Dry ice bombs (dry ice (and maybe some warm water if you want to know it will go off soon) in a two liter bottle, cap and stand back...) are just safe enough that people think they look fun and just dangerous enough that a few of them get seriously hurt playing with them.

While the schrapnel rarely penetrates skin at ten meters it'll still screw up an eye something fierce. And if you're dumb enough to stand next to it it can blow out your ear drums. If you're even dumber and hold it it can take off fingers.

0celo7

sounds like a good idea to me

dmckee

I also vaguely knew a guy who got arrested for leaving them in the bushes around a college campus. He didn't use the water, so they took their own sweet time going off and he was long gone.

0celo7

4:02 AM

you could throw it in a prof's office for extra fun

somehow smuggle it in

would be pretty hilarious

dmckee

But after the first few someone understood what they were seeing when he planted one and called it in.

0celo7

@dmckee there's cameras everywhere it's hard to believe people get away with stuff

there was a thief running rampant in one of the lab buildings and they had to have cops patrol the place

dmckee

@0celo7 This was a mumble years back, so cameras were less ubiquitous than they are today.

0celo7

@dmckee we all know your age

dmckee

All my omissions are to protect the guilty.

0celo7

4:08 AM

actually I don't know your age

@dmckee Ok I'm trying to find your dissertation but I can't

NMSU's library website sucks

dmckee

@0celo7 Yes.

Last time I wanted a copy while I was away from home I found it on the JLAB Hall C web page.

0celo7

You're at least 32

That's my lower bound

dmckee

@0celo7 ::chuckles:: At least.

0celo7

@dmckee Hey, it's my leading order approximation :P

dmckee

Put it this way, according to the old rule of thumb I shouldn't date women younger than thirty. Even if my wife would let me.

0celo7

4:14 AM

@dmckee are you DWM?

@dmckee are you sure you got your PhD from this place?

vzn

← also forbidden to date others by sig other, wheres the fun anymore :(

dmckee

@vzn With the SO, obviously.

vzn

@dmckee lol "monogamous fun" still seems so... limiting :(

dmckee

@0celo7 Probably need to use my full name, I think that's how I signed it. ::checks:: Yeah. You need my full name.

Pretty dumb search, that.

0celo7

@dmckee Got it.

That's reaaaaaly stupid.

vzn

4:17 AM

hey this is very exciting if 0celo7 can actually find your thesis... a big day... maybe he does have some )( google foo o_O

0celo7

...that year makes no sense

@dmckee Did you get a PhD late in life?

dmckee

@0celo7 I'm only just getting to "late in life" now!

0celo7

@dmckee Ok my upper bound is now 40

dmckee

But I did have a gap year and then a long time in grad school.

0celo7

Ah

vzn

4:18 AM

@0celo7 he wrote a bunch of papers & how do you know you found his thesis?

dmckee

@0celo7 Little do you know.

0celo7

@vzn I recognize his writing

dmckee

Style metrics are a somtimes thing for computers, but people are good at them.

And I suspect that I'm easy even for the machines.

0celo7

(lots of typos)

( ;) )

dmckee

^ nice.

In truth, when I got the bound copies, I opened one to admire my work and found a wordo in the very first paragraph I read.

Aaaaaaaarrrrrrrggggggghhhhhhhhhh!!!!!

vzn

4:20 AM

@dmckee so hows the job search going anyway? why looking?

dmckee

@vzn Big life change on the way. More money would be a good thing.

I'm going to a APS job expo next week to talk to industry people.

0celo7

industry???

dmckee

New Orleans, none the less.

0celo7

You don't like teaching?

dmckee

@0celo7 That's where the money is.

Especially if you're not a superstar.

vzn

4:22 AM

@dmckee so mysterious! keeping us in suspense! does vaguely remind me of KK...

0celo7

@dmckee your school must treat you really poorly, you keep talking about money

dmckee

@0celo7 I rather enjoy teaching, but I would like to do some research, too.

@0celo7 They treat me just fine—love my colleagues—they just don't pay me very much.

vzn

@dmckee (continuing) HEP?

dmckee

@vzn Well, that's my training. But I'm willing to diversify. Even big data if they'll have me and the price is right.

I do rather draw the line at bomb work. Which is too bad because they are always hiring.

vzn

ethics! admire that! wondering, have your students done any new physics experiments?

0celo7

4:26 AM

@dmckee How much does one make at a small state school if you don't mind me asking?

Cost of living is relevant too

dmckee

Well, Missouri is a low cost of living state, so the pay is lower than more expensive places, but my salary puts us at about the US median household income (i.e. in the neighborhood of $50k/yr), and I can earn more over the summer if I can get work.

0celo7

Get work?

dmckee

That's not setting the world on fire, but it's enough to buy a house and drive a decent used car.

@0celo7 You can get up to two months pay from a grant, or you can teach summer classes for extra pay. It's been the latter for me.

You can also, drive to the gulf coast live in a tent and work at a beachfront shop if you want, and I knew a guy who did that when I was young. He liked the beach.

0celo7

some people are crazy.

dmckee

Some people like the beach.

vzn

4:30 AM

← fondly remembers summer vac... :) distantly :|

dmckee

@vzn PhD comics has a strip that claims you know when the weekends and vacations are because other people are slow to answer your emails.

vzn

← saw phd comics movie and bet almost nobody else here has, so makes me a superfan among mere fans :) (bought at caltech bookstore on personal visit last summer!) :)

0celo7

PhD comics is pretty miserable

vzn

@0celo7 lol yeah youre livin it :P

0celo7

I'm not a PhD student

and I'm not miserable

vzn

4:34 AM

@0celo7 lol you write like youre pretty ~~miserable~~ jaded sometimes. and yes youre a science student. etc! oh you have a lab job now too dont you? :)

0celo7

I've had a job for a while

vzn

so whats the job anyway? what do you think of it?

0celo7

my advisor was AWOL today so I'm not getting paid >:(

need to find his ass tomorrow

dmckee

@0celo7 The first ten yeas or so are better, and he still has a good gag every once in a while, but it has lost it's edge.

vzn

track that deadbeat down! :P

dmckee

4:37 AM

And that edge was always in the black-humor department.

0celo7

@vzn 4 real tho

I need money for the Springer sale

vzn

"black humor"? oh yeah thats so ~~not~~ like 0celo7

0celo7

Hörmander won't buy himself

vzn

lol

0celo7

It's a (1,1) tensor if it can eat a vector and produce a 1-form, or if it can eat a 1-form and produce a vector. Is that definition enough to prove what you want? — DanielSank 4 hours ago

@DanielSank I think this is an unhelpful comment.

I will elaborate if you care.

vzn

4:39 AM

@dmckee maybe he should have quit while ahead, like watterson. (did you mention him once? cant remember) theres a cool documentary on him...

dmckee

@vzn Seen the documentary. He also did a week of guest strips recently (last year or has it been two) and I caught them.

At first I thought it was just someone spoofing his style, but it was so good. And he gave it away in the last panel of the last guest strip.

vzn

yeah, living legend. did see the doc, liked it :)

← wild trivia, actually recd signed response letter from watterson from his early days

dmckee

Speaking of artistic style, the film Secondhand Lions has a comic as a character and we get to see a lot of "his" art. Berkeley Breathed did them and they are great.

And the show is great, too, so that's a double win.

vzn

wow! also a big bloom county fan. delighted he was also in the watterson doc. :)

0celo7

@dmckee My expletive thermo prof clarified the $h_{out}$ thing today after the homework was due.

vzn

4:48 AM

0celo7

^ fail.

DanielSank

@0celo7 meh

Flag it as not constructive.

dmckee

@vzn I've always imagined that Gene Simmons loved that.

Not that I know, but it is so obviously poking fun at the "rock music is the devil" thing that was going around (again!) when that was drawn.

0celo7

@DanielSank No, I think it's not mathematically helpful

there's a flaw in your reasoning

vzn

@dmckee seemed more like "rock music is corrupting the young" or "rock musicians are grown up degenerates" meme. but yeah it all gets blurred together sometimes. (thinking of two stones songs, paint it black & sympathy for the devil. oh yeah, and ozzy was a rumored devil worshipper, etc) also think it closely parallels an old actual apple ad.

dmckee

5:02 AM

Hmm ... I had a couple of fishbowl macs, but I never saw an add like that from Apple. Must have lead a sheltered life or something.

Paint it Black was originally a Rolling Stones song. Did Ozzy cover it?

//Don't know my Ozzy stuff nearly well enough, but I didn't really start paying attention to rock music until he was no longer holding center stage in the popular mind.

vzn

@dmckee the stones songs have devil refs. the musicians at the time liked to "push the boundaries" (in that way, somewhat like some denizens of this room...) the rumors about Ozzy might have started with the infamous bat incident. dont think he was much linked to the stones afaik.

0celo7

@heather I'm doing the lab report

dmckee

@vzn I grew up in San Antonio, so "the infamous Ozzy event" in my part of the world had nothing to do with animals and a lot to do with a revered historical location.

vzn

@dmckee oh really? you mean the concert venue? not following. re "ozzy in popular mind", he went thru phases, and some (late) resurgence with his reality show etc...

dmckee

5:29 AM

Not the concert venue. Just google "Ozzy San Antonio".

Anonymous

6:26 AM

I posted this question on Chemistry SE (chemistry.stackexchange.com/questions/69979/…). Is it okay to repost it on Physics SE ?

Anonymous

0

Q: How to predict which gas shows maximum ideal behavior at STP ? (given its critical temperature)

Suppose we know the Van Der Waals coefficients $a$ and $b$ for a set of gases in the real gas equation, then which is the correct method to predict which gas shows most ideal behavior at STP ? Our professor said that we must check the critical temperature using the formula $$T_c=\frac{8a}{27Rb}$...

Anonymous

I think I might get some alternate and better answers from this site too.

David Z

6:42 AM

@Mystic No, you shouldn't post the same question to two different sites.

If you have a different question to ask about the same situation, that might be fine.

Anonymous

@DavidZ I am not sure which site is better suited for that question. I think physics people might be able to answer that better as the question tends more towards Physics than Chemistry...

Anonymous

( I realized that after posting the question)

Anonymous

If I don't get good answers there then is it okay to delete the question and re ask it here? @DavidZ

David Z

7:01 AM

@Mystic Sure, if the question doesn't appear on more than one site at once that's definitely fine.

Anonymous

physics.stackexchange.com/questions/316948/… Deleted and re-posted it here!

Anonymous

0

Q: How to predict which gas shows maximum ideal behavior at STP ? (given its critical temperature)

Suppose we know the Van Der Waals coefficients $a$ and $b$ for a set of gases in the real gas equation, then which is the correct method to predict which gas shows most ideal behavior at STP ? Our professor said that we must check the critical temperature using the formula $$T_c=\frac{8a}{27Rb}$...

thermodynamics ideal-gas gas

yuggib

7:23 AM

@0celo7 A self-adjoint operator that is unbounded and bounded from below (i.e. $\sigma(A)\subseteq [-M,\infty)$ for some $M\in\mathbb{R}$) has purely discrete spectrum if and only if $(A-z)^{-1}$ is compact for some (and hence all) $z\in \rho(A)$ (it has compact resolvent). Therefore the harmonic oscillator has compact resolvent. If one consider more general (closed) operators on a Hilbert or Banach space, the condition above is sufficient but not necessary (I think).

If there is a more general condition it should be on the Kato somewhere, but the one above is the one used in quantum mechanics.

With a purely discrete spectrum, the spectral family satisfies $\sum_{n\in\mathbb{N}}\lvert \psi_n\rangle \langle \psi_n\rvert =1$, yes. This is equivalent to the general statement that $\int_{\sigma(A)} P(\mathrm{d}\lambda)=1$, where $P(\mathrm{d}\lambda)$ is the projection-valued measure.

Anonymous

@JohnRennie Hello. I have some query regarding your answer here (physics.stackexchange.com/a/209562/139621). You said that the gas having lowest $a$ and $b$ should show most ideal behavior. But on the other hand $T_c=\frac{8a}{27Rb}$. The gas having highest $273-T_c$ should have the maximum ideal nature at STP. I feel the latter is the correct method. Can you please clarify? Is my method wrong ?

John Rennie

@Mystic I'm working at the moment. Back in half an hour or so ...

Anonymous

@JohnRennie Ah, sure!

skill patrol

7:42 AM

\o @yuggib

Electrodynamist

8:22 AM

Hi. Can I expect any pseudo-Riemannian manifold to obey the vacuum Einstein equation?

Anonymous

8:36 AM

@JohnRennie Are you free now ? Or else we can continue the discussion about your answer tomorrow (in case you are busy) ?

yuggib

8:52 AM

@skillpatrol o/

OBE

9:37 AM

hi

user228700

@JohnR: Morning :-) I see u've been quite busy (?)

John Rennie

@Kaumudi.H I'm visiting family (currently at my Mum's) and that limits my free time :-)

user228700

Ah, u're with family. I'd forgotten. OK, have fun :-)

John Rennie

This morning I'm trying to catch up with some of the work I didn't do yesterday!

user228700

Oh, I see. OK...

John Rennie

9:41 AM

I'm also trying to avoid eating everything in sight.

M Mum always has food lying around.

user228700

x'D Do tell me how that goes!

John Rennie

At home I resist temptation mainly by not having any food in the house :-)

user228700

:-) That's a great strategy.

Secret

Last night dream part 1: Art lessoon, think of a project, ran out of time and has to do it next lesson

John Rennie

@Kaumudi.H Epic fail so far. My mother made some cakes for a charity sale and there was a lemon cake that didn't sell left over. More precisely here used to be a lemon cake left over :-)

Secret

9:43 AM

Last night dream part 2 is similar to this:

Doctor Strange Final Battle Scene (Dormammu I've Come To Bargain)

►

user228700

@JohnRennie :-D Lemon cake doesn't so appetising though.

John Rennie

It was deeeeeeeeeeeeeeeeeeeeelicious!

user228700

So many "e"s! Wow, it really must've been one hell of a cake! :-o

John Rennie

Light sponge cake with lemon curd in the middle and lemn icing on top.

I wish I'd taken a photo ...

Secret

1. Family need to go shopping soon
2. I knocked over pack of potato chips
3. My friend clean the mess
4. I knock over the table full of things such as printers, papers, vases
5.

John Rennie

9:44 AM

Instead of guzzling the whole cake like the greedy pig I am :-)

user228700

Me too :-|

user228700

Your mom is up and about making cakes for charity?! :-) Isn't she quite old?

John Rennie

The cake was a bit like this

Secret

5. As things in chaos, time suddenly move backwards and things float back to their own place, debris reassmebles into unbroken objects etc.
6. I then try to find the pack of potato chips because I have not knocked over it yet this time
7. I knock over the table again
8. Time rewinds

user228700

Oh, Jesus, that does look delicious!

John Rennie

9:46 AM

@Kaumudi.H 84! (That's 84 not 84 factorial :-)

user228700

x'D 84! would be much older than the universe itself!

Secret

9. Rinse and repeat 3 more times, suddenly, a wall that isn't there was seen assembling in the rewind.
10. I project a doctor strange style portal, step though it and found myself back at the very beginning
11. I then found my pack of potato chips, but it is only half filled

John Rennie

Hmm, so my mother is actually one of the elder gods from before the universe existed. That would explain how she always knew what my brother and I had been up to.

user228700

:-) I see that all this food has uplifted your mood quite a bit! Is the weather pleasant as well?

Secret

.

John Rennie

9:49 AM

Yes, it's bright and sunny this morning, though rain is on the way for later in the day.

The village where my mum lives has a high rainfall and it's always muddy. Always.

user228700

Sounds lovely :-) It's always sunny in ~~Philadelphia~~ Chennai.

user228700

@JohnRennie Lol, alright, mud isn't so lovely.

John Rennie

Actually given that it's a dairy farming area, and with lots of horses, that mud isn't, well, pure mud!

user228700

Eeek! :-P I've forgotten the name of ur village but when I googled it for images, it looked lovely--a far better reality than the sunny, sticky and grey crowds of Chennai.

John Rennie

Wookey Hole

Wookey Hole is a village close to Wells in Somerset, England. It is within the parish of St Cuthbert Out. One possible origin for the name Wookey is from the Old English wocig (an animal trap)., although it is also a possible alteration from a Celtic word ogo (cave) referring to Wookey Hole Caves. The village of Wookey Hole is dominated by the Wookey Hole Caves tourist site which has show caves and a controversial crazy golf course which was built on the site of the village bowling green. The village has shops, a pub, restaurants, hotels and a campsite. The former paper mill building, whose water...

Alex

9:58 AM

@ACuriousMind Yesterday I asked why $$P_{if} = |\langle \psi_f| \hat{U}(t,t_i)| \psi_i|$$. You stated "$U_I\lvert \psi_i\rangle$ is the time-evolved state, taking the overlap with final state $\lvert \psi_f\rangle$ gives probability to detect the final state." Were you considering $|\psi_i\rangle$ and $|\psi_{f} \rangle$ as states in the interaction picture?

Should $|\psi_i \rangle$ not be $| \psi(t_i) \rangle_{I} = e^{\frac{i \hat{H}_{0} t_i}{\hbar}}| \psi_i \rangle$ in the interaction picture?

user228700

@JohnRennie Aah, yes :-)

Secret

10:15 AM

【BOFU2016】 Aleph-0 【BGA】

►

Danu

@Alex Expectation values (and therefore matrix elements) are independent of the picture anyways

Also, did you forget a square?

Alex

@Danu Yes I did. So you are saying that the Born rule (which states the probability of measuring one state in another) holds for all pictures because expectation values are independent of picture?

Danu

Probabilities, like any function of the expectation values only, cannot depend on the picture.

That's why they're called pictures: They're just a different way of looking at the same.

Alex

@Danu Okay yeah I agree with that.

Danu

What topology are you interested in? :P

The point-set kind?

@vzn I actually saw that---it was total garbage though.

Secret

11:01 AM

non hausedoff or even non T1 because that's what time travel is made of

Yashas Samaga

2

how do you do that? o0

wave function is some math thing? can that be directly observed as a real thing as shown in the picture?

Alex

@Danu When working out the transition probability from state $|\psi_i \rangle$ to $| \psi_f \rangle$ is it correct to state that " $|\psi(t)\rangle_I = e^{\frac{i \hat{H_0}t}{\hbar}}|\psi_i(t)\rangle_{S} = e^{\frac{i \hat{H_0}t}{\hbar}}e^{-\frac{i \hat{H_0}t}{\hbar}}|\psi_i \rangle = |\psi_i\rangle$"?

Emilio Pisanty

11:17 AM

@YashasSamaga see references in

13

A: Is there experimental verification of the s, p, d, f orbital shapes?

A few years ago the XUV physics group at the AMOLF Institute in Amsterdam were (to my knowledge the first to be) able to directly image the orbitals of excited hydrogen atoms using photoionization microscopy. For more details see the paper, Hydrogen Atoms under Magnification: Direct Observati...

Yashas Samaga

lol

people in facebook share all sorts of stuff without knowing what it actually means

Emilio Pisanty

@YashasSamaga I'd take it easy on that one - it is remarkably accurate for a social media post.

Sir Cumference

Morning

@YashasSamaga Woah

This the real deal?

Emilio Pisanty

@SirCumference sort of

^ process sort of looks like that

Sir Cumference

@EmilioPisanty Neat

@YashasSamaga It should be said that this picture is four years old

Secret

11:38 AM

For those who said penrose diagrams are (insert term), Check this out

Anonymous

@JohnRennie Are you around ? Did you check my query regarding your answer? ( I guess you missed my previous message so I am reposting it )

John Rennie

@Mystic hi, yes, I've finished work now. What did you want to ask?

Bernardo Meurer

@JohnRennie Found something you might enjoy

Windows 9 - The OS Microsoft WON'T Tell You About!

►

The title is silly

so is the entry

but the project is pretty interesting

Knowing your love for W7 I think you'll like it

Anonymous

@JohnRennie I feel that just checking whether $a$ and $b$ in this answer is small isn't sufficient criteria for the gas to show ideal behavior at STP. The main criteria should be the difference in critical temperature and 273 K as I said in this message. chat.stackexchange.com/transcript/message/35871919#35871919

Anonymous

4 hours ago, by Mystic

@JohnRennie Hello. I have some query regarding your answer here (http://physics.stackexchange.com/a/209562/139621). You said that the gas having lowest $a$ and $b$ should show most ideal behavior. But on the other hand $T_c=\frac{8a}{27Rb}$. The gas having highest $273-T_c$ should have the maximum ideal nature at STP. I feel the latter is the correct method. Can you please clarify? Is my method wrong ?

John Rennie

11:43 AM

@BernardoMeurer Hmm, thanks, I'll have a look. I'm getting on OK with Windows 10 now I've got used to it.

Anonymous

Also have a look at my question here so that you get my point better. physics.stackexchange.com/questions/316948/…

Anonymous

0

Q: How to predict which gas shows maximum ideal behavior at STP ? (given its critical temperature)

Suppose we know the Van Der Waals coefficients $a$ and $b$ for a set of gases in the real gas equation, then which is the correct method to predict which gas shows most ideal behavior at STP ? Our professor said that we must check the critical temperature using the formula $$T_c=\frac{8a}{27Rb}$...

thermodynamics ideal-gas gas

Anonymous

@JohnRennie

John Rennie

@BernardoMeurer As far as I can tell it's not much different to Win7 once you get below the new user interface. It boots impressively quickly though.

Bernardo Meurer

@JohnRennie It's basically about frakensteining W10 to make it more W7-like

It's that goddamn hibernation feature

I hate that thing

John Rennie

11:46 AM

@Mystic I don't think the term most ideal behaviour is well defined because non-ideal gases can be non-ideal in different ways. So I struggle to get very interested in the issue. Note that I started my answer with I'm not sure there is a single answer to this.

@BernardoMeurer powercfg -h off

Bernardo Meurer

@JohnRennie rm -rf /mnt/Windows/ Thank you very much

Delete System32

John Rennie

:-)

Windows is basically a nice OS. Spend some time grubbing about in the kernel and you'll find it's a perfectly good design. It's just all the user mode crap that gets built on top.

But then Ubuntu have done the same with Unity.

Bernardo Meurer

Ubuntu is shit

I hate that thing

I hate Debian

yuggib

If it was not for shitty website designs and pdf viewing, I would abandon the graphic interface of operative systems at once

at least for my work

John Rennie

I grew up in the era when the command line was the only interface, and I wouldn't want to go back to those days.

Bernardo Meurer

11:50 AM

You can use a framebuffer terminal and still view PDFs I think :P

John Rennie

Knowing how to do stuff from the command line is very useful, but just because modern GUIs tend to be excessively childish doesn't mean GUIs are a bad thing.

yuggib

well, let's say that if it was not for shitty websites design and poor pdf view implementation, I would need only emacs to do my job :-D

Bernardo Meurer

I cannot start using Emacs

yuggib

@JohnRennie GUIs makes you waste time

John Rennie

@yuggib you are, of course, entitled to your opinion.

yuggib

11:53 AM

I find the absence of keyboard shortcuts in GUI-based software unnerving

Bernardo Meurer

What?

Everything on Linux has shortcuts

Everything I use at least

yuggib

try to browse websites only with the keyboard

John Rennie

Most Windows GUI apps also use keyboard shortcuts.

Tab to jump between links and return to open the link with the focus.

Arrows and pgup/pgdn to scroll.

yuggib

you can't do everything like that (and it is far from optimized)

John Rennie

Most modern web sites don't work well with the keyboard, but that's because the web site designers judge (correctly) that the majority of people will navigate them with a mouse.

yuggib

11:56 AM

as I said, it is because of that (and pdf viewing) that I cannot get rid of GUIs

Anonymous

@JohnRennie I get your point. However, it seems that the answers which your method will give will vary with my method by a very large margin since you are finding minimum of a,b while I am finding maximum value of a/b. I guess I have to wait for an answer on the main site.

Anonymous

Ideal behavior is mainly defined by $Z \approx 1$ in Physical Chemistry.

Bernardo Meurer

I blame everything on Javascript

Everything

John Rennie

@Mystic I think you're hunting the snark. Define what you mean by most ideal and you can then define your criteria. But not everyone will agree with your definition.

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