physics.stackexchange.com/questions/443082/… For any mods I think this question should be put on hold.

@JakeRose That's what close flags are for. Chat's generally not a reliable way to get mod attention to stuff on the main site.

Yo. So, a typical CCD records the polarization parts of the Jones vector I_ccd=Ix+Iy. What about the Stoke's vector? Is the recorded intensity the sum of the components squared (when using fields?)

Its just S0, right?

But this assumes the stokes vector is an intensity meaure

@Chair I know, right? I managed to answer a non-lame HNQ last week also. Maybe the algorithm is improving.

@JakeRose what ACM said, plus it doesn't even need moderator attention to get a question put on hold.

I designed my new theory about behavior of subatomic particles

theory of oscillation movement

@deadpool someone moving faster than light could, in effect, travel forward in time relative to everyone else, but it's not clear what you mean by the end of the universe. It isn't obvious that the universe has an end.

morning

@vzn cannot spell

At least for large mammals, we are innicent

> New research disputes a long-held view that our earliest tool-bearing ancestors contributed to the demise of large mammals in Africa over the last several million years.

This "long-held view" is news to me.

Africa is the last place on Earth that still has relatively large and diverse populations of large mammals.

@rob There's also pretty large whales in the ocean. Their slow demise we definitely are responsible for, though :/

Meanwhile in Europe, northern Asia, Australia, and the Americas, all of the mammoths, mastodonts, saber-toothed cats, megatheria, etc. seem to have disappeared relatively recently.

The European lion has disappeared within written history --- Romans complained about them.

@rob I wonder if they were tasty :-)

Actually I suspect a mammoth would be rather chewy - it would take a lot of stewing

I thought the working hypothesis was that the African megafauna had co-evolved with human hunters, while in the rest of the world humans appeared relatively suddenly as an unstoppable threat.

@JohnRennie The sabre-tooths probably weren't - predators usually don't taste very good.

@JohnRennie I know some people who will purchase "a beef" from a butcher (perhaps an animal they've raised themselves). Typically they'll keep most of it in a big chest freezer and eat on it for an entire year.

A mammoth would let you do that for a community of several families.

But if you didn't have freezing or salt-curing, a mammoth would have an awful lot of wasted meat, whether you liked the flavor or not.

When we talk about an object's angular acceleration then do we refer to the farthest point of the object from the axis of rotation ?

Depends on the context

Also if the object is rigid, the angular acceleration should be the same everywhere

chat.stackexchange.com/users/340881

@Akash.B Um...why did you post a link to your own chat profile?

@Chair We usually migrate them to the main site unless the asker is question-banned on the main site.

@Chair Just cast a normal close vote on the meta question

Sup guyz, any idea what cool (and hopefully not hard for a beginner) electronics project I can make. I want to improve my ee knowledge and I figured out the best way to do it would be making actual things :D

Hm

There's an edition of Lee's manifolds at 130 bucks

and one at 30

What to pick!

Your nose?

@NovaliumCompany You could ask the folks at EE for advice, they might be better with hands on things like that

E.g. I know how charged particles work but I'm incompetent at building electronics

On a side note, has anyone here read Spivak's Calculus on Manifolds by chance and can offer an opinion?

My class is gonna use it next semester, but the amazon reviews are...less than favorable

I've just read Hossenfelder's blog (reading the blogs is my Sunday afternoon treat) and oh my goodness I now see why it generated so much discussion.

I think the only sane response is to immediately eat a large, calorific meal laden with saturated fats.

This has made little impact on the woeful state of contemporary physics but I feel nicely full.

science.org.au/supporting-science/science-policy-and-analysis/…

Australia Academy of Science recommended 10 points to spice up our science. Hopefully the coming Labor will help assist this goal

are those some famed cornish pasties

or other varieties of pasties

Personally, from the conversation with Labor people via their public forums, Labor has quite a commitment to science especially those related to automation. If their internal conflicts does not get the better of them, then hopefully science in Australia in the coming years will be better

@Slereah The semicircles on the left are Cornish pasties and the round pie between them is a pork pie. On the left are Cumberland sausage rolls, and in the middle are Cheddar cheese pasties. It's a Brexit training meal - for when we can no longer afford to import any food.

(why is this important? Well the NCI is part of my PhD lol!)

@JohnRennie So basically, varieties of meat hidden in dough? :P

@JohnRennie quite frightful to have to only eat english food

@ACuriousMind pastry not dough. I realise traditional German cooking makes no distinction between the two :-)

@Slereah to be fair, the prospect is terrifying.

British cooking is far better than is used to be in the dark days of my youth, but even so I wouldn't want to eat only British food.

Wait so are pasties not considered British food?

Cornish pasties are British. Quintessentially so!

only if you deny the independance of Cornwall

ahh I was thinking you meant importing the whole food...I suppose you still have to import the ingredients

@Slereah true :-)

A no deal Brexit will probably mean Scotland voting for independence, so who knows? Cornwall might be next.

> Chef John's Cornish Pasty

clearly you frequent allrecipes.com too

I sure hope Scotland will remain in the EU! Otherwise the price of whisky might go up...

Goodness, it's real

Basically looks like an easy to handle pot pie to me...though sounds like that was what they were intended to be

Whisky is disgusting

@ACuriousMind if Scotland does hold another independence vote it will almost certainly be on the basis that they want to remain in the EU. Scotland voted 60:40 for remain.

My great grandfather was Scottish. I wonder if I'm eligible for a Scottish passport.

I think they make you eat a haggis before giving you the nationality

I like haggis!

hullo

just wanted to ask a quick question - if I need to prove that $\int_{-a}^{a}\psi_n^*(x)\psi_{n'}(x)dx=0$ for $n\neq n'$, with $\psi_n^*(x)$ being the complex conjugate of $\psi_n(x)$, and am given the eigenfunctions in the form $\psi_n(x)= A\cdot\sin(k_nx)$ for even $n$'s and $\psi_n(x)= B\cdot\cos(k_nx)$ for odd ones does this mean that $\psi_n^*(x)=\psi_n(x)$ since in both cases I've got a real $x$?

@AndriiKozytskyi Yes (but you mean you've got a real $\psi$ - $x$ is always real)

@ACuriousMind yea, I did meant that, sorry. Thanks a lot!

@JohnRennie Mmmm... Haggis... :)

Also, I suspect that it's going to be Northern Ireland that goes for an independence referendum first, considering how the political scene is there at the minute

@SirCumference the reviews are mixed because it's an advanced terse book, it's one of those iconic math books

@bolbteppa Hmm, I only have multivariable calculus and abstract algebra under my belt. Haven't taken a real analysis class yet

In the beginning he sets up compactness, proves Heine-Borel, some things like Cauchy-Schwarz, in about 10-15 pages, then onto differential calculus, the hardest thing is (a version of) Sard's theorem in the middle-ish of the book which I still don't get, Munkres has an easier version of this book if you want to prep for it early

@bolbteppa I see. Though how much of a background does Spivak's expect?

Roughly just calculus, preferably his calculus book

Oh good, I'd worried that I'd need a more formal analysis class

Sigh

Sup everybuddy!

@Blue Nice new pic. :D

@Blue Looks like the steam logo + iron man's chest thing :D

@Blue Which year in uni is this for you?

@SirCumference JS seems to be all-around unpleasant

@Blue Can I ask you for an advic? I wanna expland my electronics knowledge. (Generally, I want to become better at electronics). Do you suggest just looking into circuits, doing the calculations, understanding how the circuit works... or I should get my hands dirty and start building some actual circuits?

"simulating real circuits" - I found the theorist!

@Blue You mean building real circuits, or simulating them on some web software (tinker...)?

Yep, got it.

@ACuriousMind Yeah, generally when I hear people say 'simulate real circuits' it's so that they don't make a massive design error on the real thing they're designing to be fabricated :P

@Blue Snap! Um, I think(?)

My approach is to just mess with circuits until I learn what's going on

I tried LTSpice for something and found it annoying

(I'm such a theoretical 'engineer' that I'm on the theoretical side of physics :P )

Though some of my bias may be that the closest we got to simulating circuits in school was LabView

So in the end, it's best to play around with circuits, understand what's going on... but there is no need to buy parts... etc. The simplest way is to use some sort of simulation software? Correct?

@Blue Something? I believe you mean many things :P

@danielunderwood Oh dear. I pity you and your class-mates :/

Any suggestions for a good simulation software (for beginners)?

@Mithrandir24601 yeah I run away from anything that mentions is now. Our senior lab professor was trying to replace it with something python-based, but I was unfortunately a bit too early for that

@Blue Is the book you sent me good for beginners. I mean, do they assume you have 160+ IQ to understand anything :D?

@Blue don't you work in a QC lab?

Alright got it. I was mainly interested in the method of learning. Simulating is much easier for learning than making actual circuits. The thing is, I know some stuff, some methods in electronics... but is there a "Roadmap" of electronics, because I don't what to learn?

@Blue Cool, I'm actually gonna google the topics and learn, is that good idea?

Yay, I'm gonna learn on a uni level #excited :D

Ok cool, the thing is, being the Bulgarian Pirate I am, I would like the book to have a free pdf version online :D

Yep, I just google the title and add "pdf" at the end and it works :D

I'm currently expanding my math knowledge and is actually pretty interesting.

(Khan Academy)

Well, I'll learn most of the stuff from KA cuz Sal explains quite nice and I love his deep voice :D

@Blue See you and good luck!

Anybody know about fraunhoffer diffraction?

Help I am drunk

I don't see the problem

Listen to

while drunk

no can do

Watching Infinity War

@vzn Lisi brought up the phys.org/news/… paper in the comments

@bolbteppa you free atm for a question?

@danielunderwood or anyone tbh I didnt realise so many people where online

@JakeRose as long as it's not a real question sure

Im trying to work out the fraunhoffer diffraction pattern for an infinite checkerboard pattern

I dont think the aperture function is separable though

I'm bad at optics

Honestly same

We rushed through it at quite a pace

Im three lectures behind atm

But term ends on wednesday ;)

@ACuriousMind out of curiosity, did the comment under your answer here get any responses before it was deleted?

@EmilioPisanty hows your fraunhoffer diffraction buddy?

@EmilioPisanty nope

@ACuriousMind by any chance do you know fraunhoffer diffraction?

Not more than the name, I'm afraid.

@Blue yeah thats true. apologies.

End of term stress getting at me

@JakeRose what? Which buddy?

@EmilioPisanty should have a comma before the buddy my ba

@ACuriousMind huh. So, not one of that user's best days on the site, I guess.

@JakeRose not terrible, but I'm not currently in a position to answer questions much. More of a battling a headache before I go to bed kind of deal.

@EmilioPisanty Ill post it on the main site dont worry, perhaps looking at a screen isnt the best idea?

If you ask on main, you can ping me here with a link and I'll have a look tomorrow.

Would fraunhoffer diffraction come under optics or waves?

@JakeRose indeed it isn't, I was just wrapping up some stuff and on my way out

@Blue Thanks

@EmilioPisanty fair fair

Have a nice sleep

@JakeRose Just saw your question - it's very likely to get closed. Have a good read through the site homework policy

I had a suspicion that would happen

Sadly my best attempt is what i put there

I dont know how to take it any further

That sounds implausible to me

Wdym?

The path you laid out is correct

You just need to actually do it

Mhm

My main issue is how to superpose the solutions

If you're having trouble with implementing one of the ingredients in particular, then ask about that

I perhaps should have put more detail in that the ft of the functions is another comb multiplied by a sinc function

I did say that i have no idea how to superpose the solutions in my question

As it stands, your question is basically just "do my homework for me", I'm afraid

Ill try and make it clearer

@EmilioPisanty

better>

?

@EmilioPisanty for the record I didnt intend it to be that way

I purely wanted some guidance on superposing 2d solutions

@JakeRose I'm not saying you did. I'm just saying that that's what it reads like.

Is it at least better now?

@JakeRose I don't see a big difference.

You do need to include all the work you already have done

The work Ive done is literally two diagrams in my notebook

It's not a guarantee that the question will stay open, but it's still necessary

@JakeRose then start putting pen to paper on those equations

Ive added worded verisons of what Ive done

I literally do not know how to go further

The next step in my method is superposing the solution with rotated versions of itself

And I dont know how to do that

You've laid out a working roadmap, but you still need to walk that road

Hard to do so when you're wearing a blindfold

@Blue I dont know how I could reduce it further

@JakeRose if it's the 2D that's confusing you, have you considered posing and then solving a 1D analogue?

@EmilioPisanty yes and I already have

That is the ft of the square wave

@Blue I have

Ive left the question in there to provide context, I think if I took it out it would be much harder to follow. But I have stated quite clearly the step at which I am confused and dont know what to do

@Blue the whole thing is what im having trouble with. I genuinely from the bottom of my heart dont know how I could reduce that sentence into smaller sections