The h Bar

Jim

3:02 PM

@JohnRennie will work on it

Secret

Europa water jets

Jim

meter stick for scale

Danu

lol

Never going to get that loose :P

g g

hello

please help regarding photosensors and light detection

wow

Bernard Meurer

$$V_\epsilon (a) =\text{ neighborhood of radius }\epsilon\text{ of point a}$$

g g

3:10 PM

ACuriosMind

Lemon

Bernard Meurer

What's the correct name in english for this crap?

Neighborhood?

g g

John Rennie

hello

Bernard Meurer

@Slereah @ACuriousMind

g g

@ACuriousMind

@ACuriousMind hello

David Z

@gg don't push it though

g g

3:12 PM

ok

vzn

@KaumudiHarikumar hi, centripetal force is one of those tricky aspects of physics that has a lot of ways to look at it. one way to think of it is that objects tend to stay in linear motion via newtons laws, and then the physics eqns have to be adjusted for a circular problem. my suggestion is to solve a bunch of problems with "centripetal motion" to see how it applies & get past the verbiage. see also eg this

10

Q: Is there a huge difference between centrifugal and centripetal forces?

I am doing a video for 8th grade on the subject. I'm showing the experiment of swinging a bucket of water over your head. Is there a huge difference between centrifugal and centripetal forces? Would it be wrong to say the two forces are practically the same thing?

Bernard Meurer

$$V_\epsilon (a) = ]a-\epsilon, a+\epsilon[$$

@DavidZ Halp

How do I call this?

Danu

@BernardMeurer You're talking about an open subset of $\Bbb R$?

The concept of neighborhood makes sense for arbitrary topological spaces, not just ones that are also metric spaces. In particular, "neighborhood of radius $\epsilon$" is not always sensible.

ACuriousMind

@BernardMeurer Yes, it's a neighbo(u)rhood

Bernard Meurer

@Danu This was said today in my analysis class about convergence

ACuriousMind

3:13 PM

@gg Hi

vzn

@MAFIA36790 youre thinking of getting a masters? physics?

g g

hello

Jim

he who pulleth out this sword from this stone and anvil shall be named rightwise king of all England

Danu

@BernardMeurer So are you talking about $\Bbb R$, or what?

user228700

@JohnRennie Yeah, see, I already checked that.

Bernard Meurer

3:13 PM

@ACuriousMind And is $V$ right or is there some special $\LaTeX$ symbol?

Danu

\LaTeX

ACuriousMind

@BernardMeurer There's no standard notation for neighbourhoods, although most people use $V$ or $U$

Bernard Meurer

@Danu yeah, $\mathbb{R}$

@ACuriousMind Sweet, thanks!

Danu

@BernardMeurer The usual notation for open balls is $B_\epsilon(x)$.

Bernard Meurer

@Danu Balls? What?

Danu

3:14 PM

In $\Bbb R$, an open ball is an open interval.

David Z

@BernardMeurer what, the interval? I'm not the one to ask about that ;-)

Danu

Standard notation for open sets is typically $O,U,V$.

@BernardMeurer A one-dimensional ball, in this case.

g g

@ACuriousMind hello can u please give ur email?

yasar

I have a probably very dumb question about famous double slit experiment

Danu

Again, the concept of open balls is a metric concept..

ACuriousMind

3:15 PM

@gg No, why would I?

yasar

How can you throw electrons one at a time? I mean, what kind of technology allows that?

Danu

This is hilarious:

Trump and Clinton battle over presidential temperament

►

ACuriousMind

@yasar You make a very low intensity cathode ray

Danu

^ACM goes experimental

ACuriousMind

Also, you don't really need to throw them "one at a time"

g g

3:17 PM

because I want help regarding a project/invention involving light detection & photosensors and I had asked on physics stack exchange which got put on hold and you were one the persons to put the question on hold, i am not angry or anything, but I am not getting help

Danu

@gg You can discuss that in this chat room.

g g

i need help from a person regarding photosensors

ACuriousMind

@gg What has this to do with me or my email address?

Bernard Meurer

@Danu What the hell is a ball :p

g g

are u not an expert in physics and photosensors ?

Bernard Meurer

3:19 PM

I'm just defining a neighbourhood as an interval :p

Danu

@BernardMeurer You don't know what a ball is?

g g

@ACuriousMind are u not an expert in photosensors

Bernard Meurer

@Danu ( ͡° ͜ʖ ͡°)

user116211

@vzn yes, indeed.

Danu

@BernardMeurer And I'm telling you that that's not the usual definition---the usual one is for arbitrary topological spaces, and hence does not mention anything like a distance.

ACuriousMind

3:20 PM

@gg I'm certainly not particularly qualified regarding photosensors, but I put your question on hold because was unclear what specific question was being asked. We expect questions on physics.SE to ask specific, conceptual questions.

g g

that ok

then how do i proceed???????

Bernard Meurer

@Danu Ah, I see

Danu

Furthermore, I'm telling you that your definition, is in fact the standard one for an open ball of radius $\epsilon$.

g g

that is why i am asking for email id

Bernard Meurer

Well, prof uses it like this so I'll use his recommended notation, but I'll keep that in mind

vzn

3:20 PM

@MAFIA36790 what do you want to do with coding?

Bernard Meurer

How can a ball be open?

Danu

@BernardMeurer $V_\epsilon$ is fine

@BernardMeurer Open not in the sense of punching a hole in it, but in the sense of "open interval"

user116211

@BernardMeurer Does it have limit points?

Danu

In the sense of not containing its boundary

g g

can anyone help regarding photosensors ?

Bernard Meurer

3:21 PM

@Danu But why do we call it a ball

Should I be able to see this somehow?

John Rennie

@Jim Cut a block of wood fractionally bigger than the space between the ends of the magnet and hammer it into the gap.

Danu

@BernardMeurer Because it's the obvious 1-dimensional analog of the 3-dimensional ball in $\Bbb R^3$.

The definition of a ball in $\Bbb R^n$ is as follows:

Bernard Meurer

@MAFIA36790 What does?

user116211

@vzn No, @Daniel told me it's important to learn programming; since it is not taught t to us - the basic science students at our uni. I told him to self-learn it.

Danu

$B_\epsilon(x)=\{y\in\Bbb R^n\mid |x-y|<\epsilon\}$

ACuriousMind

3:22 PM

@gg You either ask a specific question or you look elsewhere for help. Currently your requests are so vague no one will spend time on them.

Danu

So all points closer than $\epsilon$.

g g

oh

Danu

In $\Bbb R^3$, this is exactly what you'd normally call a ball (with the boundary "shaved off")

In $\Bbb R^1$, this is an open interval.

user116211

@BernardMeurer @danu told you .....

Bernard Meurer

@Danu Ah, I can see this working in $\mathbb{R}^3$

Jim

3:23 PM

@JohnRennie in the time since I last posted, a student came by and just pulled it out. Everyone else who worked there had tried pulling on it and nothing happened, but this guy just literally walked over and simply pulled it out.

Danu

In $\Bbb R^2$ this is an open disk

g g

ok here goes

Danu

You will often see people calling open balls open disks, too.

Bernard Meurer

Okay, gotta write a report

brb boys

Danu

@Jim LOL

user116211

3:23 PM

@Jim Jim-slave idea worked!!

Jim

Levers didn't work, sliding didn't work, but one person just pulled on it and it came out

Danu

THE CHOSEN ONE

user116211

@Jim He is the Arthur!!

Jim

I gave him a 3d printed crown

John Rennie

@Jim is he wearing his underpants outside his trousers?

Danu

3:24 PM

^ relevant

user116211

@Jim Generous king!!

ACuriousMind

@Jim Was that student involved in some radioactive incident earlier?

g g

ok

Jim

@JohnRennie lol, I think he's in secret identity mode

user116211

@Jim Check if he is Neo.

John Rennie

3:25 PM

@KaumudiHarikumar what apect of algebraic functions do you need to know about?

Alex

@ACuriousMind You stated that the position and momentum eigenstates are not strictly speaking quantum states because they are not in $L^2(\mathbb{R})$. Are the eigenstates of $L_z$ strictly quantum states since we can normalize them as $\langle s_z| s_z \rangle = 1$?

vzn

@MAFIA36790 couldnt follow thread, did you say you were interested in applied or theoretical physics? obv programming is much more relevant to applied...

John Rennie

@ACuriousMind bitten by a radioactive physicist perhaps?

Jim

Perhaps he's Thor

ACuriousMind

@Alex Yes

Danu

3:25 PM

TOO SLOW :'(

user116211

@Jim Who uses the Force.

Jim

mjolnir

user116211

@Jim Ultron also could lift it.

Alex

Okay thanks.

ACuriousMind

@JohnRennie I think of all superpowers that might convey, super strength is unlikely to be among them ;)

g g

3:26 PM

if, in a dark room we make a light beam of green colour and red colour intersect each other then wont yellow color be formed ?

ACuriousMind

Also, lol slow @Danu

g g

yellow colour at the point of intersection i mean

Jim

his labmates claim EM equipment always goes wonky when he's around. Perhaps he warps em fields

user116211

@vzn I'm currently majoring in phys. or specifically basic physics; they teach programming to applied and engg. physics students.

user116211

@Jim O.o

user116211

3:27 PM

@Jim Definitely he uses Force.

ACuriousMind

@gg Yes, the intersection will likely appear yellow.

g g

ok gr8

vzn

@MAFIA36790 agreed with DS that programming is really widely applicable/ useful across all areas, do you want to do your masters on applied or theoretical areas?

David Z

@ACuriousMind that is, if there is something there to reflect the light.

Danu

@ACuriousMind So unlike me :'(

ACuriousMind

3:28 PM

@DavidZ Sure, otherwise we're not going to see the beams at all.

g g

@DavidZ but wont there be scattering by dust or water vapour of that yellow spot/point ?

John Rennie

@gg Note that the fact a combination of red and green light looks yellow is due to the way the human eye works. If you mix 700nm wavelength (red) and 550nm wavelength (green) light it does not produce 600nm wavelength (yellow) light.

g g

i meant the scattering of light

ok I get it we see the colour, our brain sees it

wont scattering of red and green light be happening at the point of their intersection ? scattering by dust or water vapour ?

user116211

@vzn Very likely to do it in the second option.

John Rennie

@gg if there is dust there then yes it will scatter some light. How much dust is there depends on clean your room is.

Most optics labs go to considerable lengths to exclude dust.

David Z

3:33 PM

@gg Assuming you mean the kind of scattering from your picture, then yes, the dust is something that reflects the light.

g g

ok lets say its a normal room so normally there is some dust in the air

@DavidZ thank u yes I mean that and not intentionally spreading dust or some aerosol in the air

like normally there isn't there always some dust in air (except for clean rooms) ?

Alex

@ACuriousMind So broadly speaking we could define a quantum state as a vector in some Hilbert space $\mathcal{H}$ such that $\langle \psi| \psi \rangle = 1$ and if we are reffering only to quantum states projected onto the position basis then we can refer the quantum states as functions in $L^2$?

David Z

@gg yeah, though it doesn't matter how the dust got there

vzn

@MAFIA36790 any particular area youd like to attack?

g g

ok now lets say that a photosensor just 2 feet away from this spot / point of interaction is installed so will it detect the red and the green light (it cant see the yellow colour because colour mixing is human vision, humans can see colour) just by the scattering of the light in the air, scattering being caused by dust

user116211

3:39 PM

@vzn Mathematical physics.

vzn

@MAFIA36790 cool, any particular area? its vast...

user116211

@vzn I've still not enough idea to choose a particular topic from it; but that's for sure, I'm into it ;)

vzn

@MAFIA36790 no need to "choose" yet just wondering what areas interest you

ACuriousMind

@Alex Yes. (Although, as I said before, the position "basis" is not really a basis of states, but in most cases acting as if it is works well enough that most physicists don't bother)

user116211

@vzn Well, would say topology and geometry till now.

vzn

3:43 PM

@MAFIA36790 lol ok sounds more like mathematics but anyway its all very popular in here these days (0ce+ACM etc) :P

user116211

@vzn Yes, I was just about to say that; but sure.

David Z

in 2016 Physics Stack Exchange Election, 1 min ago, by David Z

I want to bounce an idea: people seemed generally in favor of having a chat session related to the moderator election. The next scheduled chat session on October 4 seems like a good time (as it's just past the cutoff for nominations), but there's no guarantee it would work for all the moderator candidates, and it doesn't seem fair to just schedule it then without considering the candidates' availability.

g g

?

David Z

see that and following

0celo7

@ACuriousMind >:(

user228700

3:52 PM

@JohnRennie My textbook was explaining the different types of functions and there, they've explained about this. Did you check the question that I posted on the MSE chat? I'd referenced the Wikipedia page alongside the definition given in my textbook; the problem is that I don't understand how the two definitions both define the same thing.

user228700

It's no big deal, really. If you can tell me a simple def. of the term, then I'll be on my way...

user228700

@0celo7: Did you check out Cold Turkey?

John Rennie

Quick question for the GR heads here. Re this question:

0

Q: Is the speed of propagation of Einstein's gravitational waves unique?

The LIGO Scientific Collaboration and Virgo Collaboration have announced [1] that on the 14th of September 2015, at 09:50:45 UTC, they detected a transient Einstein gravitational wave, designated GW150914, produced by two merging black holes forming a single black hole. The two black holes that m...

cosmology black-holes gravitational-waves

In the linearised limit it's easy show the wave vector for a gravitational wave is null so they propagate at the speed of light. If the intensity is great enough that non-linearities become significant does the light still propagate at $c$?

Jim

interesting question. I'd have to do the math but my gut says it stays as a null vector

Danu

@JohnRennie Numerics?

0celo7

4:08 PM

@KaumudiHarikumar what's that

John Rennie

@Danu I imagine you could only do this numerically. It just struck me that as I was about to reply to the question with of course I realised I didn't know if it applied outside the linear limit.

Jim

yeah, the thing is that the linear approximation holds very well for a broad range in this case. Something really funkadelic (<-- technical term) would have to happen for this to be the situation

user228700

@0celo7 "Cold Turkey is a free productivity program that you can use to temporarily block distractions so that you can get your work done!" getcoldturkey.com

Jim

what is there to prevent you from turning it off?

John Duffield

@JohnRennie : we don't actually know that gravitational waves travel at the speed of light. Do note that a gravitational field is a place where the speed of light is spatially variable.

0celo7

4:12 PM

@KaumudiHarikumar I can get my work done just fine

user228700

@Jim They've taken care of that. I used it for a little bit but since I mostly work on my phone, I've stopped. But yes, as far as I remember, there is a feature to make sure that you can't do anything to turn it off once it's on.

John Duffield

@Jim : Nice magnet! Stand on it with a 6lb sledge, and whack that ball good.

0celo7

Wtf what if I NEED to watch YouTube for some reason

Jim

@JohnDuffield I assume the question refers to local measurements. Global measurements are cheating. You could measure gravitational waves out at the edge of the observable universe and then complain they aren't travelling at c. But that's not going to turn any heads

0celo7

Life threatening

vzn

4:13 PM

@KaumudiHarikumar "cold turkey"? (oops nvm)

user228700

@0celo7 That wasn't meant to be an insult to you or anything. You were talking about deleting your account and all, and so, I was just suggesting. I'm sorry if you took offense; I was just trying to be helpful.

John Duffield

@Jim : it's not cheating. If a serious gravitational wave came through, you would see all the pulsars speeding up. Because you and your clocks slowed down.

0celo7

@KaumudiHarikumar what?

user228700

@0celo7 Earlier today(or yesterday, perhaps, in your part of the world), you were telling that you may need to delete your account to get your work done and that you were procrastinating by reading amazon reviews of the books you already own and everything, remember?

John Rennie

@KaumudiHarikumar: I looked at your post in the maths chat. Are you confused about how to define an algebraic function?

Jim

4:16 PM

@JohnDuffield perhaps we are talking about different things, but if a gravitational wave comes through town, measuring it becomes local.

user228700

@JohnRennie Yes. Mostly because I don't understand my book's definition. What is the simplest definition?

John Rennie

Suppose we have a function $y(x)$ and you want to write down what that function is.

By write down I just mean write it out as something you could calculate ona basic calculator.

user228700

@JohnRennie Okay...

John Rennie

And by basic calculator I mean just addition, multiplication and raising to powers.

John Duffield

@DavidZ : I think this is an interesting question, and that you should re-open it.

John Rennie

4:18 PM

can you write out all functions in this way?

Jim

@KaumudiHarikumar There must be a way to turn it off if it becomes necessary or you finish early. In which case, it becomes no more than a barrier that gives you more time to decide you shouldn't be procrastinating. But if you're determined to take a "short break", then there's no way you can both block yourself from those applications AND make them available when needed

user228700

@JohnRennie Nope, not all of the functions.

John Rennie

Suppose we have the function $y$ is $x$ squared, can you write down the function for $y$. What do you think?

user228700

@JohnRennie Uh, what do you mean? $y(x)=x^2$?

John Duffield

@Jim : hit itttt!

John Rennie

4:21 PM

Yes, exactly, it's far simpler than you think. We simply write $$y = x^2$$ Now can you write down $y = \sin(x)$ in this way.

Jim

58 mins ago, by Jim

@JohnRennie in the time since I last posted, a student came by and just pulled it out. Everyone else who worked there had tried pulling on it and nothing happened, but this guy just literally walked over and simply pulled it out.

John Duffield

@Jim : and don't tell me, his name was Arthur.

vzn

@KaumudiHarikumar so are you self-studying physics outside of a class right now?

Jim

@JohnDuffield it is now

user228700

@JohnRennie Uh...no?

John Rennie

4:23 PM

Correct. Was that a guess, or do you know why not?

user228700

@JohnRennie No, no, I know why not.

user228700

@vzn Uh, I don't attend any classes at the moment. I'm self-studying everything sort of.

John Rennie

It's because we can write out $\sin(x)$ using a Taylor series, but when we do this we get an infinite series $$\sin(x) = \frac{x^2}{2!} - \frac{x^4}{4!} + ... $$

user228700

@JohnRennie Yes, okay.

John Duffield

@Jim : your local measurements don't change because your local clocks slow down along with everything else. You only know this when you compare them with the pulsars.

vzn

4:24 PM

@KaumudiHarikumar saw that you said youre taking a year off before applying for college? wondering if youre doing (fun?) stuff besides studying? :) ... anyway think its cool what youre doing & few would have the initiative/ dedication for it :)

John Rennie

So the function $y=\sin(x)$ cannot be written as a finite polynomial. That makes it a transcendental function not an algebraic function.

The definition is as simple as that. If you can write down $y(x)$ as a finite polynomial then it is an algebraic function.

user228700

@vzn No, no, I took a year off to study harder. Every year, during the summer time, there are a flood of entrance exams that are conducted in India, for high school graduates to get into college. Even though I made it to some great universities this year, I felt that I needed to try again next year(you can only write some of these exams twice). So that's what I'm up to.

user228700

@vzn Thank you for your kind words. Haven't heard many all day :-)

user228700

@JohnRennie Okay! God, my textbook made it seem so weird. Thanks for clearing this up sir! :-)

Jim

@JohnDuffield yes, which is why local measurements are A-OK. Non-local measurements require you to factor in things that you may be unaware of, which means your results could be off and giving you something that doesn't sit with a sanity check

vzn

4:28 PM

@KaumudiHarikumar so you can still get into the ones that accepted you, even with (1yr) delay? is it that you want to try to get accepted at more prestigious colleges? ps know what you mean... are you talking about chat rooms or even outside of them? keep in mind chat rooms are not known for "kind words" in general, quite to the contrary... also there tends to be "gender imbalance" & big congrats on toughing that out :|

John Rennie

@KaumudiHarikumar It can be a bit more complicated than this, for example we could define $y$ by something like: $$y^2 +2yx + 1 = 0$$ $y$ is still an algebraic function because we can in principle rearrange the equation into the form $$y(x) = \text{finite polynomial}$$

user228700

@vzn No, I could either have joined those colleges this year or I write the exams again, next year. Since I felt that I could've done better, I decided that I'll write them again next summer and didn't join anywhere. No, I don't mean the chat rooms in particular.

0celo7

@KaumudiHarikumar nope

user228700

@JohnRennie Yes, yes, I know what you mean.

vzn

@KaumudiHarikumar possibly unkind words somewhere outside of chat? sorry to hear of that :(

user228700

4:32 PM

@0celo7 Oh, well, it was more than 12 hours ago and I'm tired so I don't want to go up and search for it.

user228700

@vzn That's alright :-)

John Rennie

@KaumudiHarikumar Although, since you were foolish enough to ask, we can have definitions like: $$y^5 + xy^4 + x^2y^3 + x^3y^2 + x^4y + x^5 = a$$ that cannot be rearranged into the form $y(x) = ...$. But this is still an algebraic function.

vzn

@KaumudiHarikumar have you looked into the online edu courses? MIT open courseware/ coursera etc? they are quite good now, huge resources out there... very well suited for self-motivated types... huge ("~paradigm") shift in that last few yrs...

user228700

@JohnRennie Erm, okay.

user228700

@vzn Yes, yes I have, thanks.

John Rennie

4:37 PM

@KaumudiHarikumar Because 5th order and higher polynomials don't have simple expressions to solve them like quadratics do. This discovery led to Galois theory.

user228700

@JohnRennie Right. OK. I'll do some more thinking before I ask again. Thanks very much sir :-)

John Rennie

But you would be wise to ignore this and move swiftly on :-)

0celo7

@KaumudiHarikumar I think I would remember deleting my account

user228700

13 hours ago, by 0celo7

I'll just delete my account.

Danu

#rekt

3

vzn

4:41 PM

@KaumudiHarikumar (lol) fyi hes resident grouch, since you seem not to have noticed yet :P

user228700

I'm gonna go to bed now. Bye.

ACuriousMind

@JohnRennie Well, I wouldn't call the expression for 4th order roots "simple" in any sense. The astounding thing is that we can prove that there's no expression, however complicated, that gives a general 5th order polynomial root

0celo7

@KaumudiHarikumar not me

Danu

@ACuriousMind tiny question: What does "the permutation $(j+1,i)$" mean? Interchanging the two?

0celo7

@vzn wtf does that mean

Danu

4:43 PM

@0celo7 It means that you're the resident grouch.

0celo7

What is a "grouch"

ACuriousMind

@Danu Yes, it's most probably such a transposition. I'm used to seeing it without the comma, though

DanielSank

Hi, everybody.

Danu

@ACuriousMind Aight

0celo7

@ACuriousMind Agreed.

Danu

4:44 PM

Hey @Daniel

vzn

@0celo7 uh, let me think... how to put this lightly... it means you like to say stuff like "wtf" far more often than anyone else in here...? :P

John Rennie

@ACuriousMind :: John smiles knowingly in an attempt to look as if he understands Galois theory ::

Danu

So you're definitely not running for mod?

user228700

@0celo7 What the hell? Okay.

0celo7

@vzn wtf does that have to do with anything

Danu

4:44 PM

@KaumudiHarikumar He's being ridiculous

@ACuriousMind What's cool is that this explains the terminology for solvable (groups).

DanielSank

@Danu Ugh. I dunno. A friend emailed me this morning saying he wants me to do so.

ACuriousMind

@JohnRennie IT gets even more astounding that the means by which one proves this is the same means by which one shows certain constructions with straightedge and compass to be impossible ;)

Danu

@DanielSank Justdoit

ACuriousMind

@Danu I learned the definition of solvable in that context for the first time, so I don't find that particularly cool ;)

John Rennie

And you can prove angles can't be trisected (phew, I remembered that much :-)

DanielSank

4:45 PM

I don't want unilateral close votes, I don't want a magic symbol next to my name in comments, and I don't understand what being a mod does for me that I couldn't do now anyway.

Being a mod seems to really be all about reviews and flags.

I don't review much, and why on earth would I want to deal with flags?

Danu

@ACuriousMind I learned about solvable from Lie algebras (terminating derived series).

@DanielSank I like doing that.

I also love cleaning up comments :D

Anyways, you should run, because we don't have 2 great candidates yet---tpg might be okay but I don't really know him/her...

DanielSank

@Danu I forgot about that. Yes, that's one good thing.

ACuriousMind

@Danu tpg is a great candidate. He hasn't been around as much in chat as in earlier days, but he's good at his niche of fluid dynamics and his meta contributions are usually level-headed and sensible.

I guess the main problem is because he only answers the rare fluid and computational questions his general visibility on the site isn't that high

But I don't see that as either a positive or a negative point for becoming a mod

Danu

@ACuriousMind Me neither, but I just don't really know much about him.

DanielSank

Oh that's the other thing @Danu, some of my earlier meta posts were less than super well thought out.

vzn

4:51 PM

@0celo7 lets discuss it sometime when youre in a good mood... :P

ACuriousMind

@DanielSank So what? We all learn over the time we are here.

DanielSank

d00d, I'm trying to rationalize not running.

vzn

@ACuriousMind myself, see an expert in fluid dynamics as a huge asset to the site =D

@DanielSank so coy, its so cute, its like youre acting whether to date a girl or something :P

DanielSank

@vzn No way, man. In that case you just go for it.

Nothing to lose.

vzn

@DanielSank me? dont even have the min rep probably. :P

DanielSank

4:57 PM

@vzn Min rep to ask someone on a date?

ACuriousMind

lol

"I only date people with over 1k physics.SE reputation"

vzn

@DanielSank huh? thought you were talking about me running... ?

user116211

Why the hell I ran short of stars ;/

vzn

lol ok now see what you were saying.

@ACuriousMind wasnt that surely your ~~fiances~~ wifes criteria? :P

ACuriousMind

@vzn What wife? oO

Last time I checked, I was single

vzn

4:59 PM

@ACuriousMind oops damn thought DS said that sorry

DanielSank

@vzn I was talking about asking people on dates.

Danu

Actually, I think Jim would be a good moderator.

vzn

@DanielSank politics/ leadership is a lot like dating actually, its just you date/ "woo" a whole crowd of ppl simultaneously... there are a lot of parallels... eg trump bragging about his "manliness" in a debate etc! :P

John Rennie

@ACuriousMind wow, I could get two hundred dates!!!

Danu

@vzn I always brag about my manliness to my girlfriend ;)

ACuriousMind

5:01 PM

> Which one is the noodle? – uhoh 12 mins ago

vzn

@Danu the big question is whether she believes/ agrees w/ you or not :P

ACuriousMind

What, exactly, does "noodle" mean when used as a term for a person?

user116211

@ACuriousMind Maybe Joke candidate?

ACuriousMind

@MAFIA36790 I don't think so

John Rennie

@ACuriousMind in the UK it is an affectionate term for someone who you think is being a bit foolish.

user116211

5:03 PM

@JohnRennie Which one is the foolish?

user116211

Doesn't sound meaningful ;/

John Rennie

Oh MAFIA3679 you silly noodle.

user116211

@JohnRennie Ohh, sounds meaningful but not good ;/

John Rennie

@MAFIA36790 it's the sort of thing a parent would say to a child There aren't any monsters under the bed you silly noodle.

user116211

@JohnRennie Sounds good!

John Rennie

5:06 PM

I've only ever encountered the term used in an affectionate way. But I suspect we are reading too much into comments that probably aren't all that rational :-)

This election has really brought the knives out.

user116211

@JohnRennie Yeh, lots of drama.

John Rennie

We need terms for the two sides. One one side we have the Forces of Rationality and on the other side we have the Silly Noodles. Yes!

user116211

Meanwhile, Kyle left comments in most of the nomination bios.

user116211

@JohnRennie I'm coming tomorrow with my stars.

user116211

@JohnRennie Maybe The Jedis vs Trumpa Loompas.

John Rennie

5:11 PM

I don't want to be a Jedi. Jedis are wet. I want to be the villain with the cool mask and red light sabre.

user116211

@JohnRennie ohh ;/ We are from the Empire then. But this time it's good.

vzn

@0celo7 one of those tricky words eh! maybe the def is in urban dictionary or something? had to go there myself last wknd to deal with a 13yr olds question on current slang... it was helpful :)

ACuriousMind

I completely agree, and it's the kind of thing I was trying to poke fun at with my nomination. This community has very clearly split into two parties that can't talk to each other, as can be seen in every recent meta thread. — knzhou 1 hour ago

The comment suggests this is merely a...catalyst for a problem that's been in the making much longer

0celo7

@ACuriousMind I have the function $f(x)=x/(1+x)$ for $x\ge 0$. I need to show $f(a+b)-f(b)\le f(a)$. I've used the MVT to show that $f(a+b)-f(b)\le a$, but I can't seem to get $f(a)$ on the RHS!

Because $f(a)\le a$, so there needs to be extra step(s).

ACuriousMind

5:26 PM

@0celo7 Have you tried just writing down $f(a)+f(b)$ and see if you can get $\geq f(a+b)$ just by neglecting positive terms?

0celo7

Of course

The denominator is bad

And Munkres says to use the MVT

but that was my first instinct @ACuriousMind

0celo7

5:37 PM

@ACuriousMind $f(a)+f(b)=\frac{a+b+2ab}{1+a+b+ab}$