The h Bar

Geocrafter

01:16

I'm having trouble drawing a FBD for one car pushing another car with a bumper. Here is what I have come up with so far: prntscr.com/mwl29p

I'm also aware there is friction, however I don't even know what is friction/normal anymore after having a force of normal horizontally.

I'm trying to solve for the force of normal between the bumpers with the provided information. Any ideas on how I found do this? (This is high school physics byw)

Secret

02:35

Hey @vzn (and others who may be interested). Recall that past dream I had where I experience that strange loss of consciousness feeling that is sunyata like? Well, last night dream brings this up to eleven:

> forgot except in a room I was asleep. I then started to think about the two past dreams where I am said by my Buddhist friends to have achieved that pure conscious state. Suddenly, I felt that loss of consciousness again, but this time after "felt seeing" that immense gray void that I "saw" in those two past dreams, the gray void quickly zoomed into a series of tunnels (it is a pure feeling, and the "visual description" of these tunnels is mainly inferred from the strong emotions that varies in intensity of that pure conscious feeling in a periodic fashion) and then suddenly, I found myse…

Tl;dr version: Possibly somehow the brain remembers those particular emotions, and then in last night dream it decided to somehow simulate it in bursts. The result is a perception of something spatial and temporal like viewing a grayscale scenery, but every gray color in that scenery are not optical colours (as in, in the dream, that scenery is not "seen", but instead "felt"), but the varying intensity of that loss of consciousness feeling at different moments of time

That is, a world where the emotion of feeling nothingness is unevenly distributed, and that give a sensation of a visual scene. A world made entirely of emotions and nothing physical

In particular, if my buddhist friend is correct in assessing what that strange emotion of nothingness I felt in the past dreams, last night dream is basically showcasing a world made entirely of pure consciousness in varying amounts

As intriguing it sounds, it is not a friendly place to "stay", the longer I stayed there, the more I felt my own consciousness literally falling apart. If this world is even real, then overstaying or entering it too frequently and the visitor will not be able to leave again (and became vegetative) as their consciousness literally get dissolved and spread out like sugar dissolving in water

Secret

03:41

My drawing skills is still too terrible to drew exactly what I "see" in that dream

But basically, the row of plowed dirt on the right drawing is something like this, but taller and sparser

and the ceiling cavern is made of rocks like these

dm__

04:04

interaction picture of QM is really nifty

dm__

04:54

$|\alpha;t\rangle_I = e^{iH_o t/\hbar}|\alpha;t\rangle_S$, nice! it's like the current Schro ket evolved back in time as if there was no perturb, like the state that it would of had to naturally evolve from

David Z

05:41

@SirCumference It sounds like that's part of the new changes.

dm__

Sakurai writes the Hamiltonian for a classical radiation field in the Coulomb gauge as $H=\frac{\vec{p}^2}{2m}-\frac{e}{mc}\vec{A}.\vec{p}$, ignoring the $\vec{A}^2$ term. isn't this assuming $[\vec{A},\vec{p}]=0$? if so, how does he immediately know that?

pZombie

06:03

1960s–present

The relativistic description of spin particles has been a difficult problem in quantum theory. It is still an area of the present-day research because the problem is only partially solved; including interactions in the equations is problematic, and paradoxical predictions (even from the Dirac equation) are still present.[5] - Does that mean that we don't really have a clue how photons behave exactly?

Is there an equation i can enter into my simulation of a single photon emitted by some source at a given location and which would then allow me to predict the chance of detecting this photon at one of many detectors spread all over my 4 dimensional spacetime?

dm__

@pZombie "All the fifty years of conscious brooding have brought me no closer to answer the question, 'What are light quanta?' Of course today every rascal thinks he knows the answer, but he is deluding himself." -A.Einstein

pZombie

we are doomed

dm__

mystery is the joy :D

pZombie

What does Dx*Dp~h even mean when considering relativity and different frames? Which frame's Dx?

dmckee

Lamb famously had a few negative things to say about the word "photon".

I think this might be a working link: citeseerx.ist.psu.edu/viewdoc/…

In 1995, none-the-less.

dm__

06:14

haha interesting! gonna give that a read

pZombie

i thought Feynman's path integral was supposed to explain exactly how a photon behaves

maybe difficult to compute a photon that takes all paths, but surely one could get ever closer to the real result by throwing more computing power on his numerical simulation... is what i believed

John Rennie

@dm__ well yes, but then Einstein steadfastly refused to accept that QFT was a valid description of reality.

dm__

@dmckee "Talking about radiation in terms of particles is like using such ubiquitous phrases as "You know" or "I mean" which are very much to be heard in some cultures. For a friend of Charlie Brown, it might serve as a kind of security blanket." sheeesh

dmckee

I think that Lamb has a very strong point there about the many different meaning which are given to the word. Some are at least somewhat consistent within their own context, but applications in different contexts often seem to differ markedly.

dm__

@JohnRennie haha true true

John Rennie

06:19

Some comments on photons here including some comments on Lamb's paper.

dmckee

Which leaves one caught between an impression of great utility and a complete uncertaintly what the word actually means.

pZombie

@JohnRennie Can i use QFT to create a simulation with a source emitting a single photon which would then get absorbed by one of the many detectors spread all over spacetime. A simulation which would give me the exact chance of detecting the photon in one of the detectors?

If i cannot, then how would QFT give a valid description of reality?

John Rennie

You need to distinguish between QFT and the method we currently use to do QFT calculations. The method we use is really a scattering calculation and while it's well suited to scattering calculations it less useful in many other situations e.g. describing bound states.

That doesn't mean there's anything wrong with QFT, but that the methods we currently use to do calculations with it are limited.

The reason that the methods we currently use are limited is because QFT is frakking hard! :-)

pZombie

I was thinking a simulation of a photon using Feynman's path integral, but going a finite number of paths in a numerical simulation. Wouldn't this give me accurate results about the chance of detecting a photon at a given spacetime location/volume of spacetime. More accurate the more paths i include?

surely someone has done this before

then again, Feynman's path integral never made sense to me. He says that the photon goes in all directions at all speeds if i understood it right. Including back in time, which sounds like back in time is symmetric to forward in time, yet later he claims that the paths back in time somehow get canceled out magically

or was that for the electron. I don'T remember anymore

bbl, i got to run and get some cat food before the storm hits

dm__

my favorite meal during a storm too

Sir Cumference

06:33

@DavidZ Huh. I'd imagine that's rather short

Like maybe a week would be more interesting

user351417

That was the change which seemed the least productive. The others should make it easier for sites to see what their HNQs are and make HNQs more effective for site discovery.

dm__

crazy this was only in 1984: royalsocietypublishing.org/doi/pdf/10.1098/rspa.1984.0023

Sir Cumference

I'm wondering what the previous duration for HNQ was

dm__

06:48

do guys have a personal favorite for a text on scattering theory? I've heard Cohen is pretty good

I've heard from many, many people that ch6 Sakurai is a headache and not worth reading, better to find a different text and then come back to it with context.

David Z

@SirCumference Eh, I dunno, 3 days seems like plenty of time to me. I would often get tired of seeing HNQs still sitting around from several days ago.

I don't know if there was any hard limit before. I think the hotness algorithm factored in question age in some way, so that eventually any question should age off the list, but it wasn't capped.

dm__

07:06

@JohnRennie excellent response for that photon thread, bravo! makes me excited to dive into QFT in the very near future

John Rennie

07:19

@dm__ I don't know anyone who loves QFT.

If you compare it with GR (the other big theory physicists have to learn) GR is simply and elegantly stated and has plenty of exact solutions to give beginners an easy way into the theory.

By contrast QFT isn't simply and elegantly stated, and apart from the non-interacting field it doesn't have any exact solutions.

Calculations end up being done by a host of cunning calculational tricks.

undefined

good morning

dm__

haha well I suppose that doesn't boost my excitement too much, but not deterred. but on that note, should we even hope for the foundation to be simple? and if so, does it suggest to you that QFT may be missing the mark somewhere?

dm__

07:40

I know there is not much to say in this direction of the topic, but have always found it interesting. that the physics is not the limiting factor, rather the mathematics used in the approach

John Rennie

@dm__ Let me try and make an analogy. The electronic structure of atoms is easy if we neglect the interactions between electrons. The Schrodinger equation gives us the usual atomic orbitals, 1s, 2s, 2p, etc.

But if we include the interactions between electrons then the interaction mixes up the orbitals so they are no longer distinct. The total wavefunction no longer separates into a product of single electron wavefunctions. Instead we have a single wavefunction.

And this total wavefunction can't be written down in any useful way. In practice we calculate the single electron orbitals first using an approximation like Hartree-Fock, then we approximate the total wavefunction as a combination of the single electron orbitals. The result works but is complicated and messy.

@dm__ Am I making sense so far?

dm__

yep, following you so far

sounds like this approximation takes up around half a page

or probably a disguised simple looking sum XD

John Rennie

08:00

@dm__ typically you use a configuration interaction calculation.

Anyhow, we get an analogous problem with QFT.

If you take a non-interacting field then you can write the total field as a product of particle states called Fock states. The total field is a product of these states in the same way that an atomic wavefunction is a product of the orbitals.

All this works fine, and it's the first thing taught to new students, but of course it's physically completely unrealistic.

Once you turn on interactions then the field state is no longer separable into a product of the Fock states. But unlike an atom we don't know how to write the total field state. We simply have no way of computing what the state is.

Secret

beilstein-journals.org/bjnano/articles/10/43

I think a cup that looks see through in one color, but opaque in another is quite cool. That said, glass already does that, but the color it reflects is IR thus invisible to our eyes

John Rennie

What we end up doing is using a perturbative expansion to calculate interactions between the single particle states e.g. starting from two single electrons we can calculate probabilities for evolving into states with other particles present. So we can calculate what happens when we collide two electrons in a collider.

But these calculations are arduous and arguments rage about their mathematical validity.

The bottom line is in QFT as soon as you move away from the simplest (unrealistic) systems life gets horrible! :-)

Secret

But can we go further, and make a material which can in a way, "cloak" the pauli repulsion for one direction thus realising a material that is intangible when held in one direction

such materials are extremely common in video game textures, but no real life examples (even limited ones) were known

Thinking about this does makes me wonder: What makes pauli repulsion so isotropic anyway...?

Mikhail

There aren't enough people in other chat rooms to appreciate my genius memes

dm__

@JohnRennie seems like it must get incredibly dense! this might be totally off base, but it seems strange to me that the product of Fock states is expected to yield anything simple for an interactive picture. would it at all be possible, if realized, to have an 'interacting basis' that makes everything nice and cohesive? speaking from no experience.

Mikhail

08:09

John Rennie

@dm__ I'm painting a somewhat negative view here. Obviously lots of people find QFT fascinating and have devoted their careers to studying it. If ACuriousMind was here I'm sure he would be rolling his eyes by now :-)

@dm__ no such formalism is known.

Maybe it's just that no-one has found it yet, or maybe QFT is fundamentally hard to approach using the methods we know at the moment.

I live in hope that some smart physicist will find the way to formulate QFT that makes it suddenly accessible, but I don't know of any progress with this for decades.

Mikhail

What do you guys mean by an interacting basis, do you mean a basis for an interaction operator?

Secret

Is there a stone weistrass analogue for QFT, I only knew that for linear operators, it has to be bounded for that to exist

dm__

@JohnRennie haha that is quite fair! it sounds incredibly mathematically cumbersome, perturbative in nature and not especially illuminating, especially in comparison to what you've said about GR. so do I gather that such a basis/formulation is not out of the picture with the theory, just entirely unknown at present?

John Rennie

The sorts of things that Arkani-Hamed has been studying are interesting. He's looking at a new formulation that is fundamentally non-local. The amplituhedron came out of that work. But I don't know that the work is going anywhere.

@dm__ it is certainly entirely unknown. It may also be entirely unknowable, but we don't know that either :-)

But chat to ACuriousMind when he gets back this afternoon. Don't let my negative view put you off. I'm really only a spectator.

dm__

08:16

woah, definitely going to check his work out, thanks! speaking, again, from no experience in the grit of that theory, it seems like whatever a simpler approach is, it must be borne out from some non-local approach. enjoyed the chat, I'll send him a message next time I see! must be going now, take care

John Rennie

Bye

Secret

yesterday, by vzn

@pZombie lol nothing to see here move along folks™ ... there is a lot of new/ bubbling developments in PWH theory but so far it hasnt much scratched establishment theory. so here you see a glimpse of the red vs blue pill™... :o o_O

if the US election outcome is as predicted, the blue pill™ will finally take over reality, and hence the return of magic. Current measures suggests reality is at least 0.01% broken, more work still needs to be done to improve this percentage

In other news, there's a version of Stone Weistrass for nonlinear operator, but once again, it needs to be bounded and not varying too much with time

tandfonline.com/doi/abs/10.1080/01630569708816764

Slereah

09:59

morning

user8718165

11:33

hello sir @JohnRennie

John Rennie

@user8718165 morning :-)

user8718165

Good morning sir, could you please explain to me how can the pressure not be equal on all sides of the container which user tmwilson26 says in (his/her) 2nd comment (comment no. 5) in this question physics.stackexchange.com/questions/213045/…

John Rennie

Take a cubical container for simplicity. And call the pressure at the top of the container P1 and the pressure at the bottom of the container P2. Then what tmwilson26 is saying is that P2 is not equal to P1 i.e. the pressure is not the same everywhere in the box.

@user8718165 is that OK as a statement of the problem? i.e. does that match what you are asking?

user8718165

@JohnRennie yes sir, but user tmwilson26 says it in context of a container around the atmosphere.

John Rennie

11:49

@user8718165 what he is pointing out is that in Earth's atmosphere the pressure decreases with height. So if we took some huge box in Earth's atmosphere the pressure inside the box would also decrease with height. To use my example the pressure at the top, P1, would be less than the pressure at the bottom, P2.

But I think there is a simpler way to understand what is going on.

user8718165

@JohnRennie Yes sir, I got it, is that because of gravity? air particles have mass so they are attracted towards the Earth and hence higher altitude atmosphere has less air than low altitude atmosphere?

John Rennie

Yes, exactly.

user8718165

@JohnRennie Thank you sir... :-)))

John Rennie

Suppose you have a 1m cube. The density of air is about 1.2kg per cubic metre, so our box contains 1.2kg of air. The base of the box supports the air, so there is a force of 12N on the base i.e. the pressure at the base is 12 N/m² higher than the force at the top.

user8718165

@JohnRennie, do you mean that the pressure exerted by gas on all sides is the same, let's call it x. But as earth attracts, the down face of the cube will be experiencing a force of (x+12) N/m²?

so down face will experience 12 more pressure than the other 5 faces?

John Rennie

12:01

@user8718165 Pressure is the same in all directions, so if the pressure on the base is x+12 that means the pressure on the sides at the bottom of the box is also x+12.

What happens is that the pressure on the sides changes smoothly from x to x+12 as you go down the side from the top to the bottom. So for example halfway down the side the pressure would be x+6.

user8718165

and AT the other 5 faces the pressure will be x newtons?

And will smoothly increase to x+12 at the bottom face and not just sudden abrupt increase?

Emilio Pisanty

@DavidZ CC @SirCumference It does (still) take aging into account, but only algebraically

86

A: How do the "arbitrary hotness points" work on the new Stack Exchange home page and in the sidebar on questions?

Basically what's documented here: What formula should be used to determine "hot" questions? We have a few tweaks: Succeeding questions from the same site are penalized by increasing amounts. So, the first question from SO in the list gets multiplied by 1.0, the second by 0.98, the third ...

(MIN(AnswerCount, 10) * QScore) / 5 + AnswerScore
-------------------------------------------------
         MAX(QAgeInHours + 1, 6) ^ 1.4

John Rennie

@user8718165 The pressure on the top face is x. The pressure on the bottom face is x+12. For all four of the vertical faces the pressure is x at the top, x+12 at the bottom, and changes smoothly as we go down the face from the top edge to the bottom edge.

Emilio Pisanty

(now with a cap at QAgeInHours = 36)

user8718165

@JohnRennie ok sir, And the pressure across the top face will be x newtons everywhere as height doesn't change? Am I correct sir?

Emilio Pisanty

12:08

but if the title is click-baity enough, and the content is controversial enough to accumulate all of those ten answers, then you're fighting the exponential explosion of a positive feedback loop with an algebraic decay factor

that doesn't end well for the algebraic decay factor

John Rennie

@user8718165 correct!

@user8718165 the pressure changes with height. Since the top face is all at the same height the pressure is the same everywhere on it.

The same applies to the base. The base is all at the same height so the pressure is the same everywhere on the base.

The pressure changes as we go down the sides because the height is changing.

user8718165

@JohnRennie I had a very bad misconception about this topic... You cleared it and now I have to solve many other problems related to fluids. I might be appearing for JEE the next year...

Thank you sir

John Rennie

You're welcome :-)

PM 2Ring

@EmilioPisanty Isn't it 3 days?

@JohnRennie Any thoughts on that xkcd puzzle I posted the other day? chat.stackexchange.com/transcript/71?m=49399562#49399562

Emilio Pisanty

12:35

@PM2Ring ahem.

yes.

each day lasts 12 hours, right?

PM 2Ring

On Jupiter, for hours that contain 50 minutes. ;)

Slereah

12:50

My brain tends to confuse Milne, Milnor and Misner

Emilio Pisanty

13:08

wait, there's an "expatriates stack exchange"?

that's ridiculous

they should rename it to the correct version, "Immigrants (but only white and affluent ones) Stack Exchange"

¬¬

PM 2Ring

13:45

@Slereah Don't forget Meitner.

Slereah

14:01

@PM2Ring Not really the same kind of topics, fortunately

But Milne, Milnor and Misner are all within my purview

Secret

14:14

Single-celled Organism Dies

►

it literally dissolves

PM 2Ring

@Slereah Fair enough. I just like to give Lise Meitner a mention when the opportunity arises. I figure she deserves it.

Slereah

GR has plenty of ladies

Ahah

That's a lie

there's only two

Yvonne Choquet-Bruhat and Cécile De Witt-Morette

PM 2Ring

@Secret You may also find volvox interesting.

Secret

14:30

oh yeah, those guys literally eat their mother alive after finished developing inside

Volvox rupturing.

►

user351417

@EmilioPisanty Here, we call Spanish people expats too, though I believe the're supposed to be called 'hispanic' rather than 'white' ¯\_(ツ)_/¯

Emilio Pisanty

14:54

@Chair where is "here"?

Avnish Kabaj

Yeah I've been trying to make sense of that as well

Emilio Pisanty

Presumably Bangalore?

Do you have a large problem with Spanish immigration into Bangalore?

Avnish Kabaj

But in Bangalore Spanish people would very obviously be expats

@Chair Where is here

Arnab Goswami wants to know

The nation wants to know

Emilio Pisanty

The point is, "expat" is a word used by many people in many contexts, but, broadly speaking it is primarily used by affluent, white migrants so that they can use or tolerate anti-immigration rhetoric (against immigrant groups coming from less-affluent or "undesirable" ethnic backgrounds, and migrating into their countries of origin, their host countries, or both), without having any of that anti-immigration rhetoric splash them despite the fact that they're also migrants.

Again, this is not the only way in which the word is used. But it is used often enough that you cannot use the label without ignoring the fact that there are situations where it's used in that way.

user351417

15:26

@EmilioPisanty Yeah, bangalore.

undefined

@EmilioPisanty I dont feel like that expat is a bad word or in anyway connected to any kind of racism. For example I'm part of the kinda large community of expat.com and I feel like there is everyone welcome, regardless nation or whatsoever

user351417

@EmilioPisanty Um, that's a kinda weird question and though I don't understand it, but I would say "no"? Is there some connotation associated with the term 'expat' which I'm unaware of?

user351417

@EmilioPisanty Ah okee. I didn't know that. I learned the word in a pretty strange way because here (bangalore) it's (to my understanding) thought of and used as a polite way to refer to all people who 'don't look indian'.

user351417

Ykes. yet another thing I need to make myself aware of before I end up in college :(

Swapnil Das

@Chair Hi!

user351417

15:31

@SwapnilDas Hello!

Swapnil Das

Are you seriously a high school student?

user351417

@SwapnilDas Um... yes, I guess? I finish 12th in May.

Swapnil Das

Same, and what level of physics do you know!

You're too advanced for your age.

@Chair How and from where did you learn all this, please shed some light :P

And btw how was chemistry today :P ?

user351417

@EmilioPisanty Since I guess there's a bit of a gap, here's my background: we have a pretty small population of non-indians in Bangalore, and I don't interact with any of them (there's an extremely small number in my school). I've only heard the word 'expat' used by Indian people, and with reference to people from all other continents/countries. I'm sorry if you feel insulted by something I said...

user351417

@SwapnilDas I'm afraid I don't get that... are you referring to the CBSE tests?

Swapnil Das

15:37

Yup, you are of different board?

user351417

Yeah, I'm doing IB. I did the CBSE 10th grade thing before moving to a different school, so a lot of the friends are doing CBSE. Hmmm, I should ping them; it's been a while.

Sir Cumference

@DavidZ Well now that the HNQ got nerfed we probably aren't going to see 50+ upvoted posts :P

user351417

@SwapnilDas Anyways, how did yours go?

Swapnil Das

Nice :)

And yes, tell me something about your vast knowledge:P

user351417

@SwapnilDas It's not really vast... I think our IB physics stuff is measly compared to CBSE's... we don't even use calculus because the IB wants to make a course called "Higher level physics" accessible to people who don't like math. But I guess I've tried looking at a couple of other famous textbooks for the heck of it.

Swapnil Das

15:45

@Chair You surely are ahead of most students. Do you want to pursue a career in physics?

user351417

@SwapnilDas Yeah, I'm planning to do a physics major (I'm thinking of research), which is among the reasons why I spend so much time on physics =)

Swapnil Das

nice.

user351417

@SwapnilDas what about you? what major are you thinking of?

user351417

I think a lot of people I know are keen on comp science.

Swapnil Das

Physics here.

I hope I could actually do a Applied Math major and Physics Minor, but no such program in India I just want to get rid of the practicals.

user351417

16:00

I just realized that I'm not entirely convinced by the agreement between the title of this meta post about recent changes to the HNQ and the actual content:

user351417

while the 5 questions per site bit could certainly be considered a step towards making the HNQ effectively allow all sites to be discovered, there's very little (IMO) which actually explicitly tackles the controversy-vs-quality issue which several answers highlighted in the thread from last October. But that's the meaning I would connect to "a little less hotness"

user351417

I would even think that the three-day limit doesn't help good questions as much as it restrains controvertial posts: a clickbait post will not live on the HNQ forever, but the less pop-sciencey posts (1, 2) which go HNQ still won't exactly get much help, right?

user351417

Thoughts?

Emilio Pisanty

@Chair I don't feel insulted. But keep an eye out for its usage.

I'm unaware of how India (and particularly Bangalore) stands with respect to immigration into India.

user351417

@EmilioPisanty I'll certainly do that. I wasn't aware of the connotation you used.

Emilio Pisanty

16:10

Say, are African migrants welcome? Are Indonesian, Bangladeshi, or Arab migrants welcome?

take any groups to which the answer is "no", and then the next time you see the word "expat" used, see if it would be used to describe that group.

@undefined I agree that most people who use the word "expat" to describe themselves doesn't think of the term as racist or classist, but that doesn't make it less so.

John Rennie

In the UK expat implies temporary residency in another country e.g. working there. It is quite distinct from immigrant.

Emilio Pisanty

@JohnRennie so you would count braceros as expats?

what about Poles or Romanians living in the UK for work, but with the intention of going back whenever that is feasible?

(not you specifically, of course. The culture you're in.)

user351417

@EmilioPisanty As far as I know, people generally say 'expat' to refer to people who come to bangalore for the tech industry and have white-collar (if that's the phrase I want: I mean primarily jobs which require lots of education) jobs, irrespective of their race, but 'migrant' is used with much less reverence, and usually applies to people in blue-collar jobs

user351417

I don't know what terminology is used among people who Indians refer to as 'expats'.

John Rennie

@EmilioPisanty yes Poles and Romanians working here but not applying for citizenship would be described as expats.

I had never heard of braceros so can't comment.

Emilio Pisanty

16:16

@Chair so more of a classist use of the term than a racist one? If indeed that is irrespective of their race, which can be a dubious claim if there is an ethnic correlation with whether the migrant is 'blue-collar' or 'white-collar' (which there generally is).

@JohnRennie I have to say that this does not correlate at all with my experience of the UK. I would be enormously surprised with that use of the term.

John Rennie

Maybe I mix with the wrong Brits

Emilio Pisanty

I don't quite see the Daily Mail raising a scandal about all of those Romanian expats stealing people's jobs.

user351417

@EmilioPisanty "so more of a classist use of the term than a racist one" exactly. I didn't get the next bit of that message.

Anonymous

Yeah, that ethnic correlation is certainly there.

Anonymous

TBF we hardly use the word "expat" in our regular (Indian) conversations.

John Rennie

16:18

@EmilioPisanty I don't read the Daily Mail. I do listen to the BBC.

Avnish Kabaj

People from other countries are of different ethnicities?

@Blue Not many expats in India or at least we don't mingle much

Emilio Pisanty

@Chair it's easy to say "oh, we don't discriminate with respect to race, we use the term for all white-collar workers, regardless of whether they're from group X or group Y" when there is a negligible number of white-collar workers from group X

@JohnRennie If someone moves to a retirement home in Spain, with no intention of moving back to live in the UK before they die, are they migrants or expats?

John Rennie

expat

Emilio Pisanty

so...

Avnish Kabaj

Expatriate

An expatriate (often shortened to expat) is a person temporarily or permanently residing in a country other than their native country. In common usage, the term often refers to professionals, skilled workers, or artists taking positions outside their home country, either independently or sent abroad by their employers, who can be companies, universities, governments, or non-governmental organisations. Effectively migrant workers, they usually earn more than they would at home, and more than local employees. However, the term 'expatriate' is also used for retirees and others who have chosen to live...

Anonymous

16:21

@AvnishKabaj Well, yeah. The cultural mixing is low here and it's mostly endemic.

John Rennie

If they applied for a Spansish passport they'd become an immigrant.

Avnish Kabaj

@Blue Delhi has a tonne of expats

Anonymous

Nevertheless, I didn't know there's any negative connotation associated with the term.

user351417

@EmilioPisanty If it's relevant, almost all expats here are Caucasian, so I have almost no sample size for African expats in Bangalore. It's just that when you look at the parts of the city where they live, you see no difference between the different nationalities.

Avnish Kabaj

@Blue Me neither

user351417

16:22

@AvnishKabaj So does bangalore, but the mixing is quite low.

Avnish Kabaj

@Chair The kids stick to embassy schools in delhi

Or the really high class ib or IGCSE schools

user351417

It's really weird to see the east-asian kids make racist jokes similar to the jokes which some Indian kids make about them.

Avnish Kabaj

My school was primarily bangali

Emilio Pisanty

@Blue There doesn't tend to be, which is precisely the point. It is a rhetorical mechanism to 'whitelist' certain types of immigration while still allowing anti-immigration rhetoric against the 'wrong' kinds.

Avnish Kabaj

Like 40-50 percent of the kids

user351417

16:25

@AvnishKabaj My school is IB, but most expats in my side of bangalore go to the two other big IB schools. In my grade of 120+, I think all of us are Indian (or Indian-origin, because lots of people used to live in a different country before moving back, so they have different citizenships) except for 2-3 korean people.

Avnish Kabaj

@EmilioPisanty I don't get it

What you're trying to say

About 'expat' being bad

user351417

:49442785 He may be suggesting that we frown upon people in blue-collar jobs who migrate, and I'm not sure whether that's true or not.

Avnish Kabaj

@Chair I see

@Chair Racism in India is super high

Emilio Pisanty

@Chair I'm not saying every use of the term is racist or classist. I'm saying there is a significant fraction of the times when it's used where it is.

user351417

@EmilioPisanty Ah, yeah. that's quite likely in India, but I'm just guessing.

John Rennie

16:29

I think it's true (in the UK) that while expat and migrant worker mean the same thing the latter tends to be used pejoratively.

Emilio Pisanty

@JohnRennie that's basically the point.

John Rennie

But then racist rags like the Daily Mail will twist whatever language happens to be convenient to suit their agenda. Does that mean I should just roll over and change my vocabulary as a result?

Emilio Pisanty

@AvnishKabaj As an example, consider an affluent British citizen, call them A, who's moved to Spain after they retire, with no intention of going back, so they have no problem with immigration as regards to them. But A is quite annoyed by Poles and Romanians who moved into their hometown and are competing for jobs with A's nephews. A is also annoyed with the African and South Asian residents in their town because (insert pointless reason).

So A wants to rail against immigration, but s/he's a migrant! what do they do? call themselves "expats", and then all immigration is bad (because they're not migrants, they're "expats").

@JohnRennie No, just be aware of the context that surrounds that term.

There's nothing intrinsically pejorative about "migrant worker"

it is, by itself, a perfectly neutral term

so, if someone is talking about some individual or community as "expats", what happens if you substitute all the "expat"s for "migrant"?

Physics Meta

0

Q: Questions about statements in papers

I often read papers and am stuck on important statements/equations that are not satisfactorily explained to my understanding. Sometimes references are provided, but even then it's cumbersome to recursively look up all the referenced material and many times the answer cannot be found in the provid...

Emilio Pisanty

does it suddenly become offensive?

(either in the abstract, or as perceived by anyone involved)

Anonymous

16:49

@AvnishKabaj Really? The only ethnic discrimination I hear about is against the North East folks.

Anonymous

Maybe you meant casteism and religionism?

Anonymous

Well, there's also some discrimination of the Northerners by the Southerners and vice versa, but I doubt we'd call that racism.

Anonymous

Oh, and there are things like these.

enumaris

17:20

weez

Kyle Kanos

17:30

Life pro tip: HNQ has an intrinsic ban on titles with MathJax in them. So if you don't think a query should be HNQ, slap in some MathJax :D:D

enumaris

$aight$

John Rennie

@KyleKanos that's interesting. If a question is on the HNQ and I edit it to add some MathJax in the title I wonder if that gets it kicked off the HNQ.

Emilio Pisanty

@KyleKanos does it actually?

huh

source?

Kyle Kanos

@Randal'Thor It's the second. The formula picks a set of questions, which we then narrow down - throw away questions picked > 3 days ago, remove questions with MathJax and ones that aren't in English, then trim per-site options down to 5 hottest, and grab top 100 for HNQ out of that. Note that the list is cached (and, under normal circumstances) recalculated every 15 minutes. Any given question isn't guaranteed to spend 72 hours in the list. — Adam Lear ♦ 1 hour ago

2

The comments shortly after state it more clearly bc this comment suggests any MathJax is banned, but it's specifically about the titles

Also, some dude "E.P." posted an "answer" in that thread that's just a thanks ;)

Avnish Kabaj

@Blue Skin color what not

Don't feel like pursuing the topic anymore

Kyle Kanos

17:35

@JohnRennie I suspect it'd take a few minutes to cache, but that may be the case

Anonymous

@AvnishKabaj I guess you use a different definition of racism. :P

Anonymous

I meant it in the ethnic sense.

Emilio Pisanty

@KyleKanos yeah, there's this annoying thing where people use their real names on professional websites but then don't want to get random internet stuff on them

Avnish Kabaj

@Blue Oh

John Rennie

Egad, I have just cut my finger.

Kyle Kanos

17:37

@EmilioPisanty use fake names

Emilio Pisanty

@KyleKanos meh

John Rennie

The cut must be 3 mm long - I could bleed to death!

Emilio Pisanty

couldn't be bothered

John Rennie

Ok, it would take a while ...

ACuriousMind

@KyleKanos are you saying your name is not Mr Kanos??? :P

Kyle Kanos

17:38

@EmilioPisanty all the cool kids are doing it

ACuriousMind

@JohnRennie Doing what? Trying to open the mint bag?

Emilio Pisanty

@KyleKanos if all the cool kids threw themselves off a cliff, would you?

Avnish Kabaj

@EmilioPisanty Ah

Kyle Kanos

I don't think I've ever said my name was that. Plus, if anything, it'd be Dr Kanos

Emilio Pisanty

(&c &c &c)

John Rennie

17:39

I don't know. I noticed my finger was stinging and when I looked blood was pouring out. A paper cut I guess. Damn, now I've got blood on the keyboard :-)

Avnish Kabaj

Expats use the term expat to set themselves apart from migrants

Kyle Kanos

Yes, @EmilioPisanty, I probably would. Presumably they were doing it right, at least

Emilio Pisanty

@AvnishKabaj Note that I'm not saying that that's the mental process that anybody is going through, or that any of this is conscious or obvious to the people using that language. But that doesn't mean that the mechanism is not at play.

ACuriousMind

@JohnRennie Given the state of cleanliness of the average keyboard, it's probably not the grossest stuff in there :P

Emilio Pisanty

anyways

Kyle Kanos

17:40

And if not, well I had a good run.

Avnish Kabaj

I get what you mean

Emilio Pisanty

@JohnRennie we should test that experimentally

ACuriousMind

Please don't kick someone's question off the HNQ by editing in MathJax. Meta has been so peaceful for a while...

3

Kyle Kanos

Can we also say the contrary & don't edit MathJax out of posts to put it on HNQ?

Well, improve its chance to get in HNQ, at least

Anonymous

Editing in some ß's in the titles would work too...

Emilio Pisanty

17:44

> Meta has been so peaceful for a while...

precisely

we should shake things up a little

ACuriousMind

@Blue are you saying they dißcriminate against people writing Gauß' name correctly? :P (I'm not sure a single ß is enough to classify the title as "not English")

Kyle Kanos

I do wonder what would constitute "not English"

Loong

@KyleKanos MathJax should not be used in titles anyway.

ACuriousMind

There recently was a HNQ question from Spanish SO with about a third of the title in spanish (it was a compiler error message with Spanish variable names)

Kyle Kanos

@Loong possibly true

Anyway, I've gotta head out to do some yardwork.

ACuriousMind

17:47

@EmilioPisanty Are you volunteering to clean up the resulting mess? :P

Emilio Pisanty

Story time! The way English detection worked in the past is that we literally had a 4MB text file with "English words" in it that we checked posts against. As part of this work, we opted to stop using that and switch to a language detection library. The downside there is that it has a tendency to mis-identify mixed-language posts (e.g. "I could say X as Y or Z in this language, which is correct?" on language learning sites). So we thought "hey, if the title's in English... that's probably good enough." Cue narrator voice: "it wasn't". :) — Adam Lear ♦ 20 hours ago

The detection library does allow some amount of configuration... it's on my list to find a reasonable compromise there, but I didn't want to delay the launch of everything else on that. — Adam Lear ♦ 20 hours ago

@Loong that's a debatable opinion

Loong

@EmilioPisanty No, it's a general guideline on stackexchange from the CM's.

Emilio Pisanty

@Loong then the CMs are wrong

¯\ _(ツ)_/¯

Loong

Tell them on meta ;-)

6 mins ago, by Emilio Pisanty

> Meta has been so peaceful for a while...

Emilio Pisanty

... as regards that debatable opinion that they hold

@Loong why? what practice would that impact?

Anonymous

17:51

@ACuriousMind Hehe. Now that you mention, I just tried searching for ß and it returned all instances of "SS".

Anonymous

I wonder why is that.

Emilio Pisanty

we've been using mathjax in titles since the beginning of the site

Loong

9

A: Is MathJax in titles a problem? And why?

It can be rather problematic, and we ask that you do it only when the extended markup is really needed for the meaning of your question in the title. That might be quite often, depending on the questions you ask, we just ask that you consider it. Titles are a major part of how search engines ind...

ACuriousMind

@Blue Because double s is the way you spell ß in a font that doesn't have ß.

So good searches synonymize double s and ß

Emilio Pisanty

@Loong I'm not particularly concerned with the way other sites do things

Loong

17:53

The reason is the same.

Anonymous

@ACuriousMind So...ß wouldn't be classified as non-English (in the titles)?

Anonymous

Probably depends on their implementation of the HNQ algo...I guess.

ACuriousMind

Well, I don't know how the "language detection library" they use works :P

John Rennie

@EmilioPisanty it's a fair point that using MathJax in a title will affect Google's indexing of that page. But I find it hard to believe it will make that much difference. There's still all the other text in the post to index with.

And to be fair Tim Post's reply says it's OK to use it if you need to. But then, why would I use MathJax in a title if I didn't need to?

My interpretation of all this is that we should continue to use MathJax in titles if it makes the meaning clearer.

Loong

@JohnRennie People write many things in titles that doesn't belong there. ;-)

Anonymous

17:57

@JohnRennie Math SE and Math Overflow would be heavily affected. :/

Emilio Pisanty

6886 questions in SEDE with MathJax in the title

heck

-1

Q: Can equation of an SHM be of the form $F=kx+c$?

A ball of density $\rho_0$ is dropped from rest from the surface of liquid of variable density that varies with depth h as $\rho=\rho_0(\alpha+\beta h)$. Will the motion of ball be SHM or some other periodic motion? My approach: I tried to find the net force acting on the ball. It comes out t...

homework-and-exercises newtonian-mechanics fluid-dynamics harmonic-oscillator

I don't think the MathJax is the primary clarity problem with that title

I mean, arguably there is an onus to take stuff like this

0

Q: Why is the proton (uud) lighter than the $\Delta^0$ (uud) baryon?

Neutron has quark composition udd with spin $1\over2$. $\Delta^0$ baryon has quark composition udd with spin $3 \over 2$. On wikipedia it says that $\Delta$ baryons have mass of approximately $1232 \frac{MeV}{c^2}$ while the neutron has mass of approximately $~939 \frac{MeV}{c^2}$. Why is the...

particle-physics mass quantum-spin standard-model quarks

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