The h Bar - 2015-08-02 (page 2 of 4)

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5:02 PM

@ACuriousMind ELI5?

@KyleKanos Geometric quantization considers a space of complex functions on the phase space, which are essentially the prequantum states. It then "polarizes" the phase space into positions and momenta, and throws away every prequantum state that depends on momenta. On the remaining functions, you would now like to define a scalar product, which, mimicking $L^2$, should just be given by integrating the products of functions - but there are several choices of the measure we could integrate over.

A metaplectic correction is "just" a choice of such a measure, essentially.

This is not appropriate sunday night banter

Maybe make a joke about bums instead

Not enough GR

(bums are funny)

We haven't had Duffield in a few days, that is good news

@Slereah I'd state oppositely. We chased him away and now it will be even harder to convince him he's wrong :/

5:14 PM

But will we, that is the question

@0celo7 Which is just the right amount of GR.

I've had to deal with a lot of cranks

They do not budge easily

@ACuriousMind That's more like ELI22, but I'll take it.

@ACuriousMind are you reading Straumann yet

@KyleKanos Well, I'm not great at explaining esoteric mathematics in simple terms ;(

5:16 PM

Which is why math is dumb

@0celo7 No, my energy is currently being spent on finding out where the hell my Polyakov loop goes wrong.

Or if it goes wrong

I know what the issue is

Back when I was looking for a job, people in job interviews were asking me to describe my master thesis in simple terms

And I was like

"No"

It was not something that could be done

^ Bad answer

They want to see you be able to communicate complex ideas to unlearned people

@KyleKanos I've heard this a billion times from my technically inclined family

5:19 PM

yeah but like

It was not really a thing I could do

Then I would be of the opinion that you probably don't know what you did

Them hiring you was not really a thing they could do either.

The title was "Quantification ambiguities in path integrals in Riemannian spaces"

That is not a thing you explain to a layman

IMO, everything can be reduced down to be explained to a non-scientist

Sure, if you strip away all meaning!

5:20 PM

If you can't do that, then, IMO, you've not thought hard enough about what it is that you've done

If I were a hiring manager and someone told me they couldn't explain their thesis, their application goes in the trash

And I don't mean to be a jerk here about it

That's just the point of asking the question Explain to me your thesis

I agree with Slereah - Producing something the layman "understands" often is something that is unrecognizable to someone who actually understands the technical thing.

Yeah but what I did was basically abstract math

@ACuriousMind That isn't the point though.

I couldn't pretend to say something like "Particles smash into each other"

(being technically accurate)

If you can't articulate your thesis to someone, how can they believe that you'd be able to articulate "complex job work" to other people who don't do that?

5:24 PM

The point is you need to be able to explain whatever you're working on to the people paying you -- laymen.

Because they were not complex job work

They were mostly programming jobs

@Slereah To you, maybe, but to other people? Probably not.

Yes, but I can explain programming jobs

Those are not hard to explain to a layman

You're not getting the point

You can pretend the computer is a little man doing a job

Well how would you have explained that thesis to a layman

5:25 PM

How can you convince someone that you can articulate programming to someone else if you can't even articulate something you spent two years working on?

That's the point of answering that question, showing that you can articulate something complex to someone who doesn't understand it

Well yes, but you are assuming that it is always possible

or at least easily done

I believe it is always possible

Well how would you have done it in that case

It might take some thinking, or borrowing insights from someone else in the field, but it absolutely can be done

I would have tried chopping it down to being about quantum mechanics of something (not really sure what your title even means)

Well yes but that is what I mean by removing all the content

I basically said "math stuff"

5:29 PM

Right, and you failed to do that

There isn't a need to be technically accurate

Loosely correct with generalities is what they want

But it should be at least saying something

Just not the field of research

Right. And part of your job of understanding what you're doing is being able to ELI5 (Explain Like I'm 5, if you're not aware)

@KyleKanos I think this is so superficial.

@Danu How so?

I guess the others already raised the main objection

5:33 PM

That you're not being technically accurate?

You can explain anything, but it'll just be stupid and dumb if you explain to dumb people.

user image

Seriously?

It will not at all reflect what you've been doing

@KyleKanos I think you are heavily biased by working in a field where you can actually say vaguely accurate stuff like "I simulated exploding stars" and people will nod and be content.

Welcome to the world of modern windows, ocelot

5:34 PM

@Danu Agreed, it won't reflect the actual work put in. But that's not the point. Interviewers don't want you to be technically accurate, they are literally testing your abilities of communicating

What you can do is a 2 minute summary for general physicist audience.

@Danu Er, that is what they want

@KyleKanos No, because they're not physicists

So "general physicist audience" = "my colleagues" then?

...and that changes a whole lot

I spent about 2 hours trying to explain the idea that you can accommodate more general things than the physical space we live in under the umbrella word "space" to a friend who is really not stupid (he's doing his MSc. in biomedical sciences atm) and he still didn't get it

5:38 PM

@ACuriousMind (a) that was a small (but long) part of my dissertation, the other bit being a bit more complex than that (b) I've had a few conversations with physicists from varying backgrounds (atmospheric, condensed matter theory & experiment, cosmology) and they all feel the same way, so I don't believe it's me being biased due to my field

@Danu Well it's a good thing that you don't have to convince the interviewer about technical details of anything, just that you appear to be capable at doing so

The whole point of the question is to see your ability to communicate. It doesn't have to be technically accurate (without them being familiar with your research themselves, how are they ever going to know?) or extremely detailed. Your answer has to be clear and cover the notion of what you do (preferably without "the lingo")

Is it actually communication if I am able to transform my work into saying nothing of substance, that nevertheless convinces the listener that they understood something?

For people who really don't do any science, it'll have to be completely useless then.

What you're describing doesn't really seem to meet the goal of communication as "information exchange" to me

atmospheric, condensed matter theory & experiment, cosmology < those are all pretty simple things to explain to a layman, though

@Danu Who says it has to be useful? (beyond the point of getting the job)

5:43 PM

It's more about the "seems legit" than anything else

Do you guys even know how businesses work?

^nope

Makes sense

If I don't end up in academics I'm pretty solidly screwed

Ahah

Tell me about it

I work in the business now

5:44 PM

(also note that I'm the only one here who pretty much agrees with you) @KyleKanos

So boring

Which I can totally explain, btw

to a layman and all

@Danu I'm baffled people would disagree with him.

It just seems a bit unfair to expect the same level of explainability from theoretical physics

@0celo7 It's called "ideological" but I guess you Americans forgot about that a while ago...

@Slereah I think this is (a) false and (b) heavily biased that those not doing QFT aren't doing "hard" science

5:45 PM

Could have been worse, I suppose

It wasn't QFT!

I did a fundamental mathematics degree at some point

Call it "hard math" or whatever you want

Man we're getting into this damn discussion again? :( It's getting a bit old

Good thing I didn't have to explain some cohomology business or whatever

It's BS to call that "hard" and other fields "easy" when it comes to describing it to layman

Also you seem to confuse "abstract" and "hard"

Those fields involve concrete objects that a layman know about

Hence you can explain more readily since it involves less things to build up on

5:47 PM

@ACuriousMind can you gimme a hand: I don't understand the following

I'll just simply disagree, it's not worth the effort to get into it

Oh... typing it out I got it @ACuriousMind lol

@KyleKanos I applaud you

@Danu Haha...happens to me regularly

And please, don't forget that we love you

@Danu Love it when that happens too

@Danu Damn right everyone loves me

:D

5:49 PM

Trying to formulate the issue makes it go away, best feeling.

@ACuriousMind Also copying the textbook's text in this case, but close enough ;D

@KyleKanos <3

I don't like that, lately, we've ended up in these discussions where it turns out some of us feel like their branches of sciences are not valued.

I just want all of us to be happy

But this isn't about things being values or not :O

I know those branches are just as complex

and important

If not more, because you can actually get money from them

user image

Can we just shut up about it? I think your (way of conveying your) view lacks nuance

No need to be snippy

5:53 PM

@Slereah Sawwy

user image

@KyleKanos That irks me. Truth is true regardless of our beliefs. Science approximates truth, but need not always be true itself.

Truth being True seems like a tautology

@ACuriousMind sigh SO GERMAN :D

Tautologies are the best kinds of truths :)

3

5:55 PM

Why Capitalize Certain Things?

Why is god capitalized by so many people?

God is capitalized in the context of the Christian god.

@Danu I bet ELU.SE has something on that

@Danu Heh, I guess it is

@Danu Proper nouns kinda thing

22

Q: When should the word "God" be capitalized?

Aside from proper noun usage, like "We're on a mission from God", when should "God" be capitalized? A few examples: That's a god awful question. Oh my god! No god-damn way. He played the part of the cannibal god It occurs to me that whenever used for decisive emphasis, by referencing deity, i...

sigh....my Google-fu is too good sometimes

I didn't even try searching for it, but: Thank you, wizard!

Oh...did I tell you guys that someone on PSE called me a diplomat the other day?

6:00 PM

I bet it wasn't Dilaton

Unless, do diplomats hate science?

@0celo7 Nah, he's not allowed to comment or anything for a while longer

@KyleKanos The way you phrased that makes me think diplomat is an insult now.

Don't worry, we'd never call you a diplomat!

Well it was after I commented on someone's post about it being non-mainstream (using my auto-generated text thing). It was weird & out of the blue from this guy

@KyleKanos In what context?

Hmm, he must not know what that word means.

He should have asked Dilaton for some colorful comments on you.

6:06 PM

Yeah, like being a gullomized zombique politician

@KyleKanos Nice

@KyleKanos How does your wife like being married to Gollum?

Well she's not a fan of Gollum (or really LotR), so I imagine she hates it

I can picture you petting your Linux cluster whispering my precious...

If I had one, I might

I'd probably even actually make its hostname MyPrecious

6:09 PM

Did your university not have one?

They do, but it's a 30 minute drive away (but available via university network)

Can I put an expanding thing on my toolbar for game shortcuts?

Like a folder thing

@0celo7 - Like a folder?

@Richard Yeah but not something that opens up a file explorer thing

There's a way to do this on Macs...

I just want to move all my games to the taskbar

SO you just want a list to pop up?

6:13 PM

Have you tried dragging & dropping the icon (shortcut) to the taskbar?

@0celo7 I'm voting to close this chat message as unclear what you're asking.

4

@ACuriousMind - Too Broad

@ACuriousMind but I served your VTC crusade loyally

this is how I get repaid?

@Richard yes, also looking at that link I didn't see at first

@0celo7 I am a cruel master.

2

@ACuriousMind not helping that whole BDSM thing

6:15 PM

@0celo7 - I used to use a popup desktop manager called OBJECTDOCK.

You just mouse down to the bottom of the screen in the right place and a docklet pops up with all your links on it

It would be nice to be able to start a game without having to go through steam menus

@KyleKanos I want all of the shortcuts to be under one icon on the bar

@Richard OSX much?

@0celo7 - Similar, but better.

Urgh I hate myself right now

Why does $k^m\equiv 1\mod n$ for $k,m,n>1$ imply that $m$ and $n$ are not relatively prime?

6:30 PM

Relatively prime numbers have a gcf of 1, right?

gcd, yes :P

Same thing

I know, I was being a pedantic asshole :P

Oh... wait

The thing is actually

If $k^m\equiv 1 \mod n$ for $m,n>1$ and $\varphi(n)=|\mathbb Z_n^*|$ and $m$ are relatively prime, then $k=1$

So my question is: Why does $k>1$ let us construct a gcd>1 for $\varphi(n)$ and $m$

IDK...I had a single class on number theory like 12 years ago

This is not even number theory, but algebra :\

Going back through the book, I found "Euler's theorem" $a^{\varphi(n)}\equiv 1 \mod n$ where $a$ is relatively prime to $n$

6:39 PM

The only time I ever saw that type of stuff (modulo) was in number theory, never saw it in my algebra classes

I guess you didn't get to ring theory :P

@Danu Let $m$ be minimal with the property. If $k$ is not $1$, it is another unit (with inverse $k^{m-1}$). A power of a unit is again a unit, so the powers of $k$ form a subgroup of the unit group of order $m$. By Lagrange's theorem, $m$ divides the order $\phi(n)$ of the unit group.

Every other $m'$ with the property is a multiple of $m$, and the statement follows.

But the "unit group" always has order 1

so it's kind of trivial that it divides $\varphi(n)$

also you didn't use the relatively prime property which makes me very suspicious

@Danu What? The unit group is $\mathbb{Z}_n^\times$

I.e. the group of units in the ring

It doesn't have order 1

@Danu Nope :/ Never had college-level algebra though (it wasn't required for physics)

6:43 PM

@ACuriousMind but we're only regarding $\mathbb{Z}_n^*$ as a group here

so it only has a single unit

Anyways, you didn't use the crucial property :\

@Danu I showed that $k \neq 1\implies m\lvert\phi(n)$ for the minimal $m$, which implies that $k\neq 1$ imples that no multiplie of $m$ and $\phi(n)$ can be relatively prime

Ah maybe you just went too fast for me :D

By contraposition, this means that relative primality of $m$ and $\phi(n)$ implies $k = 1$

I feel like Euler's theorem should give a more direct argument, but thanks anyways :)

I think the proof of Euler's theorem uses a similar reasoning, I've seen these statements before

Or at least, one possible proof uses such a reasoning

6:47 PM

Also why is $\varphi(n)$ the order of the unit group?

@Danu ...didn't you define $\varphi(n) = \lvert \mathbb{Z}_n^\times\rvert$ up there?

Maybe I showed a totally different statement from what you actually wanted to know :D

@ACuriousMind By unit group, do you mean the multiplicative group of invertible elements in $\mathbb Z_ n$?

@Danu Yes

why do you call it unit group?

Because invertible elements of rings are usually called the "units"?

6:49 PM

^wat

That's what confused me about your argument

Unit (ring theory)

In mathematics, an invertible element or a unit in a (unital) ring R is any element u that has an inverse element in the multiplicative monoid of R, i.e. an element v such that uv = vu = 1R, where 1R is the multiplicative identity. The set of units of any ring is closed under multiplication (the product of two units is again a unit), and forms a group for this operation. It never contains the element 0 (except in the case of the zero ring), and is therefore not closed under addition; its complement however might be a group under addition, which happens if and only if the ring is a local ring. The...

but it sounds like unity

also Vinberg doesn't use it

nope.. not even "unital" appears

A unital ring is just a ring that has a multiplicative identity (not everyone defines general rings to have one)

@ACuriousMind Okay, so that's a ring with unity in my terminology.

This is why I think unit for "invertible" is a bad idea :P

@Danu Ah, I also learned it as Ring mit Eins.

6:52 PM

@ACuriousMind So who came up with that terrible idea to call things "units"

@Danu Dunno who, but I think it is because e.g. the factorization in a UFD is unique "up to multiplication with units", and multiplying with unity does nothing, so multiplying with units does "not much", but I could be totally off the track here.

UFD?

something something domain?

unique factorization domain

I thought so ^^

Also known as "factorial ring"

6:56 PM

aka the identity element for mult

@skillpatrol ?

@skillpatrol no, that was the point: Units are not just the identity.

oops, sorry for jumping in :P

@skillpatrol tsk.

I should not buy those big one liter bottles of energy drink

I am all freaking out

7:06 PM

@Slereah Yup, sounds like a terrible idea.

It is.

But who could resist such a bargain

Redbull is horribly expensive

Birrell and Davies is a pretty great book

Ginseng and caffeine give me the gitters

Wald's book on the topic is a bit too specialized for my tastes

Birrell does like the whole shebang

@0celo7 :(

Kung Pow! Enter the Fist - Trailer HQ

7:12 PM

what is that^ ? a Bruce Lee remake :P

So bad that it's good

looks so ... mindless :D

Best of Kung Pow! Enter the Fist

hmm, I can upload images from my PC to the chat??

yup

I've been wasting all this time uploading to imgur!

7:21 PM

yup

@0celo7 Meh uploading to imgur is very fast (if you have the chrome extension)

@Danu for some reason it always freezes for me

(and I've tried it across 4 devices and 3 OSs)

user image

whoa

@Danu how can I upload from my PC with this extension

-2

Q: Why can't people just pump water from ground and flood deserts to make them habitable?

I know this may be the wrong site, but I'm a curious man and I want to solve world's problems. One of big problems is deserts. They're so dry that nothing grows there. I was thinking about this and why can't people just install pumps that flood the deserts and keep flooding them nonstop until ...

oh god why does adblock no longer work

@0celo7 Because you turned it off?

@0celo7 Too many arrows

7:29 PM

@KyleKanos I'm very sure I didn't turn it off

Then you need to update it

AdBlock Plus

@skillpatrol that's what I have

my old computer is blocking just fine

reinstall it

sometimes that works for me :-)

what the hell none of my chrome extensions work

7:33 PM

Shutdown restart

^

still nothing

is this the iPad?

no, reinstalled everything and now it works

crazy

that imgur extension broke Chrome

imgur is full of ads

7:38 PM

Try Ghostery (chrome webstore link)

@skillpatrol it broke hoverzoom, wolfram alpha and others

my computer has been acting up, time to see if Windows Defender is worth a damn

nothing

Bluh

I have that feeling when you look at science stuff and you think like

BLUHBLUHBLUH

I need more sleep :V

whenever I start Win I see a program or something flash for a second in the toolbar

I have no clue what it is

I can't find it anywhere

1

A: Why can't people just pump water from ground and flood deserts to make them habitable?

If you pump out ground water faster than it is replenished, it will be depleted, sooner or later (http://water.usgs.gov/edu/gwdepletion.html )

Seriously?

This user does this wayy too often. This should be a comment, not an answer.

Link looks legit though

Not saying it justifies an answer

7:52 PM

Sure, but link-only and all that

Yeah, it's link-only for sure.

That's what it is

I've been through this guy's answers a few times. The average quality is abyssmal.

I pushed it into the LQ queue

Can you imagine: 500 answers and less than 10k rep?!

Well, I'd bet his ratio of upvotes to "time spent on answer" is impressive, though

@ACuriousMind Sigh...

7:55 PM

Where are the PSE servers?

the European users can respond to each other faster than I can read the messages, it's crazy

451

Q: Which tools and technologies are used to build the Stack Exchange Network?

What tools and technologies are used to build the Stack Exchange Network? See also: Which tools and technologies are used to build Data Explorer? Return to FAQ index

support faq stackexchange technology tools

NY, CO, OR

I am dumb

5

(though technically the NY one is NJ)

star that

@ACuriousMind Look at his badges though ;)

7:57 PM

Why Aren't Lasers Doing Cool Shit?

He's also that JK+#@&#@$KJ that did 1000 reviews then straight up quit.

@Danu Really an example where the gamification has gone wrong.

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