@BernardoMeurer Do show it, then!

@ACuriousMind I can do it in a little bit, let me just finish one thing. When do you leave tonight in UTC?

Soon, I have to get up early tomorrow

Dangit, it takes a while

We will do it tomorrow then :P

Does it require me to actively participate? Because if not you could just post it whenever and I'll look at it when I can

@ACuriousMind A bit because i dunno how much you know about CS

and I like interaction, I'm a lonely soul

@BernardoMeurer wow why won't you show me

Because talking to you about hating ZFC is preaching to the choir? :P

ZFC isn't that bad. It's classical logic that's the ur-devil.

@obe So, uh...could you send the logo?

i may have to remake it since I don't remember if I saved the psd.

@obe ...

@0celo7 I told you I'd show you on Skype

Reb would be mad if I ditched her for you :P

So basically ads/cft is a consequence of stokes theorem in non-trivial spaces right?

@kevinTahN. wat

Yes

everything is a consequence of stokes deep down

I said it ahahahah

@ACuriousMind QFT is because of stokes

integration by parts

yes in deed

I am going to just concentrate on understanding EM from now on

No AdS/CFT is a very deep phenomenon where one theory on the boundary is equivalent to another theory in the bulk because you can map their degrees of freedom into each other. If it were just Stokes' theorem you would expect such a bulk/boundary duality to hold for all theories, but it doesn't. You can't put an arbitrary theory into the bulk and expect there to be an equivalent theory on the boundary.

@ACuriousMind I understand that it is not true for all theories, but the fundamental mathematical trick that empowers one to make such a statement in the first place or to contemplate it is Stokes theorem

has anyone been in freezing weather for over 5 hours in a row?

I think completely not mentioning stoke's theorem makes the whole ads/cft thing seem esoteric for no reason

As a result of the math trick you can then make two theories equivalent via partition function, and compute corr functs and start spitting out papers

@kevinTahN. I'm really no expert on AdS/CFT at all (I barely know what the correspondence states) but I don't think there's any justification for that. Just because Stokes' theorem also relates something in a bulk to something on a boundary doesn't mean that the AdS/CFT correspondence rests on it.

See this question where joshphysics says essentially the same.

I don't do ads/cft either (not because it is for super smart people), but I have thought about it for a while, Obviously everything becomes complicated and esoteric once you give physical significance and cast it a certain way

The point I see is in particular: Meaningful bulk actions are not integrals of total derivatives (because then they would be trivially constant under variations), so what do you even want to apply Stokes' theorem to here?

Give me a minute, I will pull out a stackexchange link too

physics.stackexchange.com/questions/63469/… look at Trimok's answer

I will leave the argumentative semantics to his response

@Slereah yo what's the name of that wave book

"because then they would be trivially constant under variations" . . . . Do you mean you get 0 under variations? Sometimes math speak hurts my head. Anyways. I can draw a lot of baby pictures about what I mean though hehe

@kevinTahN. It seems to me that the application of Stokes' there is a rather trivial step. The essence of AdS/CFT lies in showing the equation after that, i.e. that the correlators on the boundary actually are equal to the partition function from the bulk.

That is the physical content and that is the completely unexpected and deep result.

Anyone feel like examining my question physics.stackexchange.com/q/310472/93165 -- I'm not saying my conjectures are rock solid, but I was hoping the idea would be given a little more careful thought than it has gotten so far...

@ACuriousMind I agree "that the correlators on the boundary actually are equal to the partition function from the bulk" . Yes but the step before that though trivial is essential and necessary.

@kevinTahN. Many computations rely in some essential step on Stokes' theorem. I think it is not very useful to call any of them "basically a consequence of Stokes' theorem" unless Stokes' theorem is actually the most non-trivial step in the derivation.

You're free to differ in your usage, of course; I just don't think it conveys any useful insight.

amazon.com/dp/0521136369/…

@Slereah

@ACuriousMind You might be right about the no new insights thing, but to me noticing and thinking about the steps in the process, helps understanding what is going on, and builds confidence.

at least for me personally

Anyways I have been obsessing over trivial things in E&M lolz

the above comment is unrelated to my ads/cft comments

↑ tabloid cites arxiv, rare!

@vzn "published in Cornell University’s online library arXiv" == "we do not quite understand the difference between arxiv, peer-reviewed literature, and random websites"

@rob sentence is literally correct. lots of ppl talk of "publishing" on arxiv including professionals. not saying the tabloid writer(s) do understand. so how do you think that sentence should have been written? think other variants might have negligible )( difference in meaning.

ps re bell loopholes, have you seen this?

dammit, did acm go to bed

@vzn I would have at least linked to the paper, which doesn't say that it's been submitted anywhere. Computer graphics people maybe have different standards about peer-review than I'm used to --- after all, if you can see the movie, you can tell that they used some tool to make those images.

@ACuriousMind Can I make an appointment for tomorrow

@ACuriousMind this projective representation stuff is crazy

I would like to reserve the 10-11 EST timeslot if possible

I was mostly remembering some crank theory supported by the statement "published by Cornell University" with a screenshot of an arxiv abstract page. Maybe I'm too grouchy.

@rob not disagreeing with your points but still dont understand (exactly) what youre objecting to. maybe you want them to mention its not peer reviewed? agreed the word "publish" is quite (over)loaded with meanings. also arxiv is not really a "library" but maybe instead an "online repository"...

there was another ref awhile back, see what you think of this one if you have more time to kill :|

@rob yeah actually a nice writeup of how arxiv is filled with crank papers might be nice, have never come across such an article and arxiv is now what, over ~2 decades old?

@vzn I'm not objecting very hard.

@rob anyway the articles filled with criticism of her results by other scientists, so its sort of like a public cyber peer review... :o

@vzn Paul Ginsparg wrote a a nice piece around its 10th anniversary, which is roughly when he left the project. Basically the "review" process at arxiv was for many years "this submission appears to produce a useable PDF file which is shaped like a scientific paper." There are some other features now, like text-overlap detection and the author sponsorship system, which have been efficient enough at catching the garden-variety cranks that they've started vixra.

@rob am aware of the basic mechanics. but it seems nobody has ever written a survey of all the crazy papers on the site. except maybe woeginger P vs NP (a sort of fascinating page in a weird way)

@vzn Someday I'm going to put together an upper-level undergraduate course with a title like "physics for crackpots", with a syllabus that covers weird ideas that most people take seriously and weird ideas that most people reject and how it is that we make reasonable decisions about which is which.

@rob fantastic idea! there is a fun book called "physics for poets" that my old neurobio teacher liked :) ... trying to remember the name for this in sociology/ science, think its called the demarcation problem or something like that

White people on suicide watch!!!

@vzn That's a common title ... took me a while to find it but you reminded me of this:

It's Time to End 'Physics for Poets'

@rob Sorry about being so argumentative in physics.stackexchange.com/q/310472/93165 , but that back and forth was actually quite helpful, as it helps me double-check my thought processes on this admittedly bizarre idea.

@rob nice! collect stuff like that for blog. :) (saw public lecture by wieman once in boulder, luvd pingpong gun!) ofc the classic is 2 cultures/ Snow en.wikipedia.org/wiki/The_Two_Cultures

hey hey

@0celo7 That book doesn't seem to cover multiply connected spacetimes

unfortunate

though I did find eventually a paper dealing with that issue

@JohnRennie your Google-fu misled you here :P The tautological one-form does not have much to do with the tautological bundles over $\Bbb CP^n$ (or other Grassmannians)

@Danu Indeed, though I realised that quickly enough to avoid too much embarrassment :-)

The tautological bundles are called such because each point in a Grassmannian is a linear subspace, and the bundle simply lets this subspace be the fiber over that point.

The tautological one-form is called that because of what MBN explained.

Tautological bundles are super awesome though :3

I find most of diff geo super awesome. I guess it seems more mundane the more you know about it.

Old question searched due to this week's newscientist reading:

Thank you :-)

I don't feel a day older than 56!

(possibly because I'm not a day older than 56 :-)

Work, surf Facebook, answer physics questions, eat lunch, read SF book ...

But I might have a drink or two on Friday night - just one or two mind.

I could ...

@JohnRennie Hey! Happy Birthday :) Long live the Rennie Santa :D

Thanks :-)

I was going to have a vegetable risotto today, but I could make myself a special meal seeing as it's my birthday.

I could try those frozen parathas

But I still haven't thought waht to make to go with them.

It sounds very weird to have a system that basically act like any other system, but has no free parameters (hence no information)

To be honest I'd probably buy a ready made curry. That chole I've posted pictures of is very nice and that is ready made.

Happy birthday, John!

Thanks :-)

@Kaumudi.H why?

Happy birthday

So how old are you now

you old man

We'll see how you feel tomorrow!

@Kaumudi.H What would go well with parathas? Something richer? A more creamy/buttery curry maybe?

Happy Birthday !!!! @JohnRennie enjoy your day

Thanks :-)

@Slereah Saturday morning is likely to be the test. I might be out for a couple of drinks on Friday night :-)

@Kaumudi.H How about if I add some cream to the chole?

Hmm I'll have to think about this ...

I think it would go well with a creamy/buttery chicken curry.

Offhand I don't know of any really good ready made chicken curries, so I'd probably have to make that myself.

What I'd probably do is buy a basic curry sauce or paste then add extra bits myself to make it nicer.

A paste is effectively a mixture of spices - cumin, coriander, etc - in oil. You use it instead of having to keep all the different spices.

Then you can add any extra spicing for specific curries.

And add cream, butter etc

That would be nice. I'll have a think about where I can buy that in Chester.

I do like the texture of paneer ina curry.

I'm getting hungry now :-)

Is paneer somewhat similar to haloumi?

I always eat a big dessert. It's usually something horrendously sweet like cake.

Anyhow, birthday or not I have to get back to work now for half an hour or so. Back in a bit ...

@Danu IIRC paneer is a bit more crumbly than haloumi.

But they are basically quite similar, yes.

@JohnRennie Oh is it your birthday? Happy birthday, then!

Thanks :-)

Yeah same, didn't realise it was your birthday, I thought birthdays cannot be found in the profiles

@Secret I was wondering about that too. I never look for them but I don't think the birthday is publicly visible

Well I guess Johnrennie's fame is so great that people knew a lot of things about him

@Secret Actually Kaumudi wished first and others followed suit. Even I didn't know his bday.

I see

@Kaumudi.H I figured as much. No matter how famous you are the system still will not display your birthday :-P

@DavidZ Mods can see the bdays ? I remember filling it up during sign up.

@anonymous I dunno, let me check

It seems we cannot

ah, well... maybe. It might be under the PII section of the profile (personally identifiable information). At least it shows up there on my own.

Though I don't want to go clicking through other people's PII unnecessarily.

PS: Even if somehow the birthday can be somehow be extracted from the birthday, people will celebrate my birthday wrongly unless known beforehand. I have a unified set of personal information that I used throughout the internet so as to protect my privacy by not putting my actual personal information unless it is a banking, institution or a government related website

@Secret that's smart

bonus point: That identity along with that set of personal info is also my active accounts. I use that identity to manage forums, games, graphical apps and other registerations

I felt like anyone knowing even my real name outside of controleld conditions will have repucussion that I don't understood to my future

However, here's the interesting thing: There's one thing about me that is common in that identity and my institution one: My personality traits.

@Secret I have a question about electronic configuration and electrode potential of vandadium. May I ask ?

@anonymous Actually scratch that earlier comment; it seems that we can access the birthday if we need to. I looked through some of the private mod documentation and it mentions the birthday being one of the pieces of information we have access to. Though I don't remember ever actually seeing that field in someone else's profile. It must be well enough hidden, and there's never any reason for us to go looking for it.

@DavidZ Oh I see. Thanks

so what's your question?

Anyway I must be off for now

Why I don't consider my personality as my privacy is an interesting question that I have no idea why

@Secret What is the t2g effect that affects the reduction potential of V(+3) to V (+2) ? Why does it cause a sudden decrease in magnitude of the reduction potential ?

I couldn't find any info about t2g effect on the net but it is mentioned in my textbook

It says 3d(3) configuration is more stable than 3d(4)

@Secret You there ?

I am still thinking, I only knew t2g is related to high spin low spin complexes but in order to change redox potentials it means somehow it is more energy costy to add the extra electron on 3d(3) to make 3d(4) (which may be high or low spin depending on the ligands attached as they affect the ligand field splitting

vanadium is also not the type of complex that can experience jahn teller distortion thus that kind of explanation will be out of the picture

Did you check the values of reduction potentials?

Or will I give you the values ?

It's -0.26 V from 3+ to 2+

This was the quote from my book ^

See the last sentence

The comparatively low value for V is related to the stability of $V^{2+}$ (half-filled $t^2g$ level)

By "low" I think they mean low in magnitude.

ok that makes sense. There are 3 degenerate $t_{2g}$ orbitals in a $V^{2+}$ and by hund's rule, 3 of the are filled with the d electrons, hence half filled. As for why half filled is more stable, I need to re-read the quantum mechanical reason

Recall that in crystal field theory in an octahedral configuration, there are 2 d orbitals of e$_g$ symmetry and 3 d orbitals of t$_{2g}$ symmetry

@Secret But that is Crystal field splitting isn't it ? Why should it occur in absence of attacking ligands ?

I thought the splitting takes place only in coordination compounds

$V^{2+}$ usually cannot exist alone (unless you are dealing with solid states, which I kinda forgot the more complicated electronics of them as the orbital smmetries will also depend on the lattice symmetry). In your level, I suspect all metal ions are solvated meaning, e.g. that $V^{2+}$ is actually $[V (H_2O)_x]^{2+}$. This is especially trule when you are considering redox couples as at your level, these couples are dipped in electrolyte solutions

@Secret Oh I get it now. That H2Ox makes sense. Thanks a lot :)

Even at research level, V2+/V3+ couples are usually found in flow cells thus the ions are solvated

Also if there are absence of ligands, then all d orbitals will be degenerate and you only end up with [Ar] 3d3. t2g and eg symmetries arise because of the orbital overlap of the ligands (or in crystal field theory, the electrostatic field of the ligand, simplified as a point charge, distort the electron density at the metal centre

Here's a more quantum mechanical explanation, which roughly speaking is that unpaired electrons screen less, but I suspect your exam does not need that level of details

@Kaumudi.H date of birth is a common security question on web sites. While I doubt it's a big risk, sharing your date of birth could be exploited by someone wanting to commit identity thert.

Some websites nowadays are harder to register, because they ask for your mobile number (in order to send sms confirmation). Even if you have a spare phone, theoretically, people can track your living address via GPS unless it is a burner

Having said that, most service I registered are before this SMS system is inctroduced

Before roughly around 2013, gmail don't need mobile numbers

what's everyone's bday here?

"A fiber bundle $\lambda$ us called locally trivial if there is such a family {$U_i$} of open subsets covering $X$ that restriction of $\lambda$ onto every $U_i$ is trivialization"

just planning presents is all

Aren't all fiber bundle locally trivial?

cos i'm planning presents for myself

by getting ppls birthdays

@Secret Interesting :)

happy birthday John

I only want one material based present: A bag of antihydrogen and a bag of metallic hydrogen

however nobody can do that thus such request is irrelevant

wont that explode tho

if the bags touch

yeah, thus one must quickly segregate it after receiving them

metallic hydrogen is easy, it is just a solid

(Of course this assumes metalllic hydrogen does behave according to theory that it survives the decompression, otherwise there is no point having diamond anvil cells in your backyard keeping the stuff stable)

SEcret what is your dob and addy

I'lll do my best to give you this

what is addy?

address

No, no netizens can have my address, I know too little on who/what you are

dob=24/5/1992

who cares what/who I am

if I was a baddie, why would I have to target you when there is a whole world of people to target

(NB I know some of you will ask that obvious question about my previous message. Let me tell you, you already knew the answer to that question)

what obvious question

cryptic mode You knew the answer, lol

My username is not named that for nothing

i dont' get it

@Secret what state do you liv ein?

Aust Syd

so NSW is the state

QLD here

@Kenshin Secret might be a rich and famous guy. You might be missing out on the chance of targeting him :'D

@anonymous yes good point

>_> What on earth is Slereah doing in SecretLabs...?

wtf australian government has banned online poker

Last night dream=Something religious sounding

@Secret Why does oxygen stabilize higher oxidation states more than fluorine in 3d series ? Any idea ?

For example MnF7 is not stable but MnO3F is stable

Another instance: V(+5) is found as MF5 form only for VF5. VCl3, VBr3, VI3 are not stable and need oxygen to stabilize them like VOX3.

Other than steric crowding of the electron density in the highly electronegative and closely spaced fluorine atoms, I have no idea

The only CSE question does not have any answer to the more general question:

Actually, we might be able to argue about size in VX$_3$ where X=/=F. X is a lot bigger than F, you cannot possibly fit that many around a V ion

@Secret Yeah, that is a really interesting fact. $F$ isn't stable even in low oxidation states like VF2, however VCl2,VBr2, VI3 are all stable. Same applies to $CuX$. So it seems like flourine isn't good at stabilizing higher oxidation states for the reasons you mentioned (probably) and it isn't even good at stabilizing lower oxidation states. It is good at the middle oxidation states. However, Sc/Ti/V/Cr can reach their highest oxidation states:+3,+4,+5,+6 respectively with the help of F.

@Secret Ok, I agree with that. Seems legit.

@Secret I suspect that oxygen can form multiple bonds while Florine cannot. O and F have the same size but with lesser number of oxygen atoms (nearly half) you can stabilize a higher oxidation state. This might be a reason. I'm just guessing.

Deep frying in animal fat is pretty good, but

This is what my frier looks like when not in use

Up here in the north of England it was traditional to cook chips in beef dripping, however it's very rarely done now. I suspect the BSE outbreak killed off the tradition.

Time to bring it back, @JohnRennie

I'm at a point in my life where I don't get money as present anymore and so I mostly get trash presents

that come "from the heart"

So it turns out it was a lie!

I guess people assume that I can make my own money now

which is a lie

@Slereah Are you a student or do you work as professional ?

I think for my birthday I will ask for Global Lorentzian Geometry

And Choquet Bruhat's book

Neither

i am on the dole

@Slereah Really ?

@Kaumudi.H The trouble with being a 56 year old bachelor is that anything you want you tend to just buy (e.g. laptops :-). So I'm almost impossible to buy presents for.

Welcome to the future of doing a degree in theoretical physics

yeah that is the trouble of adulthood

Anything cheap enough to buy, you can buy yourself

Anything too expensive is too expensive to be a gift

Gotta find the sweet spot in between

When you get a something I made gift it's nice because that person has gone to some trouble on your behalf. The nice part is knowing that they value you highly enough to put the effort in. But ...

... well ...

... the gift itself is usually rubbish :-)

@Slereah So are you planning to switch to any other field ? Or academia?

Yes, and it's nice to know people are thinking of you.

I am already in another """field"""

@Slereah What field ? Other than physics?

The computers

Softwares

Well I do get chocolate truffles for christmas

which is nice

I see. Wish you all the best for your endeavours :). Honestly, you made me a bit scared now. I was planning to a degree in theoritical physics, but I guess I'll have to change my mind now ! @Slereah

@Kaumudi.H No, after btech.

@Kaumudi.H younger, though the age difference has ceased to be significant now we're both middle aged :-)

My state won't even offer me dole if I am unemployed :P

The biscuits he gets me are called torcetti

From some obscure Italian bakers in London. And they are delicious.

They do look a bit like dog poo :-)

I've never eaten dog poo so I can't say what it tastes like, but the torcetti are absolutely delicious. They are similar to amaretti in texture.