The h Bar

Sir Cumference

12:00 AM

You'd use photoshop to create vectors? >_>

Get a better program

I'm 99% sure photoshop is made for rasters

Still, very impressive

Kelthar

Vector programs wise, Inkspace is pretty cool for such a tiny program, my only experience with vector graphics, but made me fell for them, just saying ^^

Sir Cumference

@Kelthar Illustrator is better :P

Though inkspace is pretty good

Bernardo Meurer

Inkscape is free software

GNU BITCH!

Kelthar

Yeah, but Inkspace fits my needs. Plus, not 1GB and open-source :)

ahaha xD

Sir Cumference

@BernardoMeurer You use Inkspace?

Bernardo Meurer

12:05 AM

Ever since my digital systems class requires a proprietary IDE for programming the FPGA's I've been more extreme

Sir Cumference

Huh...

Bernardo Meurer

@SirCumference I can't even draw on paper, I can barely write, let alone on the computer

Sir Cumference

I've never even used photoshop for vectors, much less know how to

Bernardo Meurer

I used MS Paint some 7 years ago, does that count?

Sir Cumference

@BernardoMeurer Well I used Apple Preview for pixel art 8 years ago, so you're still better than me

Kelthar

12:10 AM

@BernardoMeurer just out of curiosity, is that IDE Xilinx related?

Bernardo Meurer

@Kelthar Mother of god, yes

Vivado

obe

I use illustrator for other stuff

Sir Cumference

@BernardoMeurer Do you never use the reply button? :P

Bernardo Meurer

That thing takes up all my bloody disk space

@SirCumference Nope, too lazy

Sir Cumference

@obe I remember making a high school animation for my physics class in After Effects

obe

12:11 AM

I did that too

Sir Cumference

Huh, really?

obe

not for physics

for french lmao

Sir Cumference

XD

obe

but I used after effects and those timestamps to move stuff

dropbox.com/s/xb7h013tuijggyx/bernardobatman.png?dl=0 @BernardoMeurer

like???

Kelthar

@BernardoMeurer My university had us using an older program from Xilinx, called ISE Design something....

Sir Cumference

12:12 AM

That was my first time really using AE

Took hours upon hours

Just to get a 5 min movie

Bernardo Meurer

@Kelthar Yeah, ISE was even worse than Vivado!

@obe Dude!

obe

wait don't save that one i made it better

Absolutely gorgeous!

3 seconds

Alrighty

12:14 AM

@obe I have to wonder how you made vectors in photoshop

I thought it was impossible

Kelthar

@BernardoMeurer yeah, besides, it was from like, the Windows XP era or something (used it two years ago). So the recommended method was using the uni's linux virtual machine dedicated for this software... I managed to get it working on Windows 7 directly, but Windows 8 people couldn't... it was a nasty experience

obe

@BernardoMeurer dropbox.com/s/ua7r686s3phgfsb/bernardobatman3.png?dl=0

Bernardo Meurer

@Kelthar Yeah, it's just horrible really, and other FPGA's aren't better

Hopefully Intel's acquisition of Altera will yield something

obe

@BernardoMeurer I didn't remake the penguin though because I was lazy and it had a lot of curves.

do you care?

Bernardo Meurer

Not at all

This is awesome

I owe you coffee

Sir Cumference

12:15 AM

@obe You certainly beat my 5-min BM signal XD

obe

xD well technically it wasn't fair because I remade it

Bernardo Meurer

it's a 17.6MB image, lol

Sir Cumference

@obe Yeah, but I wouldn't have thought to make a vector :P

obe

@SirCumference one flaw with your remake was that it was messy

Bernardo Meurer

@obe So cool

Sir Cumference

12:16 AM

@obe Well yeah, it was for the laughs

obe

if you tilt your screen back and look from underneath you'll see the mess.

Sir Cumference

I intentionally made Bernardo's head huge

obe

when I made the first one for danielsank I basically remade the circle and gave it grainy texture (although it was sloppy but I did it in 30 seconds)

so if you looked at it from any angle it would look like it was original

Sir Cumference

One of the newer things I've made in Illustrator was this Astronomy SE logo

obe

@SirCumference or also the octopus you made, it was hd where as the image itself was pixelated, you could have feathered it a bit and added grain to make it fit.

@SirCumference you designed that?

Sir Cumference

12:18 AM

@obe The site's still in beta, I just made one for myself :P

obe

oh

Sir Cumference

I hoped to make the A look like a tripod

Didn't have any ideas on how else to make it look

obe

hmm

Sir Cumference

Now with my userscript, Astro SE looks like this

obe

cool

Sir Cumference

12:20 AM

I'm still probably going to revamp it a lot

idk how to do that

Do what?

userscript

You know JS?

nope

I know english

rob

12:21 AM

:34869013 Deserves to go on the astro meta. Very nice design.

Sir Cumference

@rob Thanks :D

obe

@SirCumference yo

rob

... suddenly (removed)

obe

you need to learn how to do

colour corrections

Sir Cumference

@rob Well, I'm still working on it :P

obe

12:21 AM

it will make your image look way better

Sir Cumference

Plus I think I need a license for a planet earth image on the bottom

@obe The entire thing is shoddy for now

I'm gonna fix it, of course

I'll probably make a vector background instead

obe

@SirCumference your pie is finished if you want it in blue or another colour.

want me to send?

Sir Cumference

Sure

obe

will you use it though? :(

or let it gather dust in your downloads folder lmao

Sir Cumference

Er, depends

If it's not entirely blue, probably :P

@obe BTW, you should learn JS

It's very handy

Knowing how to program + graphic design is really useful

obe

12:26 AM

ehhh

lol I accidentally closed without saving

i lost all of it

the only version of it that exists is the one i sent you

Sir Cumference

The end

obe

it's because

I thought I saved it

and since I did a bunch of edits to it that were bad

I wanted it to reset by reopening it

but I realized I didn't save

Sir Cumference

Just send me the psd :P

obe

the psd is gone dude

Sir Cumference

Woah what

Welp

obe

12:27 AM

i did it in one shot

Sir Cumference

Why?

obe

i didn't save in between

idk that's how i roll

Sir Cumference

Bad habit, man

I save my psd's or word documents every 5 seconds (exaggerating)

It'll save you from a lot of stress

obe

photoshop has recovery mode

I recovered it

but it's an old version

here dropbox.com/s/2f2vy13pqqbl9j4/spacepie.png?dl=0 @SirCumference

Sir Cumference

Still blue... :P

And save it

obe

12:33 AM

I tried making it pie colour and real colour for the astronomical objects

but it looks like trash

so

it's either I 3d model a pie

Sir Cumference

Well I created this mess in 3 clicks

I'm far too lazy to edit it further

obe

yea

it looks bad lmao

and also

you're forgetting

the inside of the pie

Sir Cumference

Well why would you even start it in blue?

obe

has to be pie colour

Sir Cumference

35 secs ago, by Sir Cumference

I'm far too lazy to edit it further

obe

12:35 AM

if I make the inside like a pie

the astro objects will look bad

since they blend on dark colours

Sir Cumference

I thought you were trying to make the inside glassy

obe

yea

i mean the bottom and the back

Sir Cumference

Oh

obe

anyway brb food xD

Sir Cumference

well brb got work to do

Slereah

12:38 AM

@JohnRennie why did they censor the scrumpy

vzn

1:54 AM

@BernardoMeurer are you doing something with FPGAs?

Bernardo Meurer

@vzn Was, not anymore, my Digital Systems course used it a lot

vzn

@BernardoMeurer what did you do with them? heres a neat recent app... spectrum.ieee.org/robotics/robotics-software/… also microsoft is getting into them heavily, seems to have major untapped potential... wired.com/2016/09/microsoft-bets-future-chip-reprogram-fly

Bernardo Meurer

@vzn Just basic stuff to learn VHDL, I implemented the Enigma machine, and I built a digital lock system

vzn

@BernardoMeurer o_O way cool itd be neat if you wrote it up somewhere

Bernardo Meurer

It all sucks :P

vzn

2:05 AM

@BernardoMeurer (sigh) its a major accomplishment! dont dis yourself :(

Bernardo Meurer

No, really, it's horribly broken, and it's all crap code, I swear by it :P

It was very hard, and I am proud of it, but not portfolio material

if I get around to cleaning it I'll put it on GH

vzn

@BernardoMeurer no, really, its a big deal & am sure Turing would be proud :) vzn1.wordpress.com/2016/07/25/… ... wish youd do a speaker session on Computer Science about it... dont tell anyone but there are grads that regularly show up in the chat who are quite clueless o_O

Bernardo Meurer

Oh, damn, I could do that I guess

I need to go over the project again

it's been >2 Months

I have a picture of Turing by my bedside :)

and one of Tsiolkovsky

vzn

@BernardoMeurer a mod on the site just refd to Turing as "someone whos been dead over 60yrs" ... alas the post got deleted before had a chance to quote him the next day @#%& :P (coincidentally that descr accurately applies to einstein also...)

Bernardo Meurer

Hahahaha

It's a shame what happened to Turing, really

he envisioned rigorously what we would only be able to implement much later with EEPROM type finite state machines

vzn

2:12 AM

@BernardoMeurer agreed, intl disgrace. but hey, working with the ~~WarMachine™~~ Dark Side™ can get you in trouble... did you see Imitation Game? vzn1.wordpress.com/2014/11/20/…

Bernardo Meurer

I did, very nice movie

I liked it

vzn

did everyone in class do a similar FPGA project or were there other variations?

heather

hello again

hmm, anyone up for the joule-thomson effect?

along with the thermoelectric effects?

Bernardo Meurer

2:29 AM

@heather That's a good pick up line

heather

uh...wat? ::searches for hidden pun::

Bernardo Meurer

There isn't

I'm just being silly

David Z

11

Q: Choosing the name of the chat room

The name of the chat room was recently changed to the h bar(becue) as a joke because of the multiple posts about food made by the more rapscallionary members of the room. I've seen a few rather terse posts suggesting that not everyone is happy with this, so maybe we should try and arrive at a co...

It seems we have a consensus?

heather

yes, i think so

@DavidZ

@BernardoMeurer phew, okay

ACuriousMind

help

Why does clicking the question score no longer show the up/downvote split?

David Z

2:33 AM

Huh, still works for me

Did you refresh everything?

ACuriousMind

Hmmm

interesting, there seems to have been a change in where the scripts come from; I now have to whitelist one more domain for executing scripts in order to see the vote split (and have the menus in the top bar actually drop down)

David Z

What's the new domain?

ACuriousMind

ajax.googleapis.com

David Z

Huh, for me that's been required for ages

ACuriousMind

Hmmm...maybe I somehow accidentally disallowed it again

David Z

2:37 AM

I suppose they could have shifted around exactly what functionality uses stuff loaded from Google and what doesn't, but it seems somewhat more likely you accidentally disallowed it

ACuriousMind

@DavidZ Looks like it; no answer other than "change it back" has remained undeleted afaics

David Z

@ACuriousMind yeah, and furthermore people seem to be in support of my suggestion on a future policy (although that's not nearly as clearly supported as changing the name back)

Sir Cumference

I can't believe I've given up 70% of the rep I've accumulated

heather

@DavidZ uh...how do you know that? they seem to be equally supported, if yours is not more supported.

Sir Cumference

And the people I gave it to got rid of it all

heather

2:44 AM

@SirCumference who'd you give it too?

Sir Cumference

@heather Obliv, obe (before he deleted his account >_>), I forget the others

Obliv left

obe deleted his account and the rep with it

heather

@SirCumference i'm sorry....meaningless internet points mean a lot to me as well.

^sadly not that sarcastic =P

Sir Cumference

XD

Physics Meta

0

Q: Proposed tag: polymer physics

I've posted a few questions here relating to physics of polymers in solution, and I am surprised every time that there is no dedicated tag for them. A couple of examples of my own questions: Hindered rotation model for flexible polymers: deriving the Flory characteristic ratio, and Scaling argume...

feature-request

Sir Cumference

Almost 2 weeks till 0celo returns

Still hoping MAFIA and Obliv come back...

David Z

2:48 AM

@heather The fact that there are multiple answers suggesting changing the name back, and all of them have significant upvotes, means that's more clearly supported than my proposal for a future policy, which is represented by only one answer

Of course, there are no competing proposals at all, which makes it kind of trivial

heather

@DavidZ but they were probably upvoted by the same groups of people.

Sir Cumference

@heather Oh by the way, nice presentation

David Z

@heather Yeah, but maybe not. And also consider that multiple people thought it worthwhile to post answers suggesting that the name be changed back.

Sir Cumference

The only thing I'd be hesitant about saying is that spacetime is "flat". There are some things quite surprising about this

heather

@SirCumference thanks

@SirCumference yeah....like i said, not the best.

Sir Cumference

2:53 AM

@heather I'd recommend reading this. It's a short and easy introduction to a pretty important part of geometry/GR.

Non-Euclidean geometry

heather

okay ::clicks link::

@SirCumference ooh! <3

Sir Cumference

@heather The one most people are familiar with is Euclidean geometry. However, Non-Euclidean geometry is pretty important too.

heather

@SirCumference drawing triangles on oranges =D

Sir Cumference

@heather Yep :)

heather

and pringle's chips

Sir Cumference

2:55 AM

You'd find the angles add up to more than 180 degrees

@heather And here, less than 180

heather

@SirCumference right, yeah

@SirCumference read and enjoyed very much

Sir Cumference

@heather Woah wait, that fast?

heather

@SirCumference yeah, it's not a long article

though i have been told i can read rather swiftly

Sir Cumference

So yep, different models for the universe include different shapes for the universe

heather

hmm...i wonder what postulate you would use for a shape of the universe that was the inside of a sphere.

Sir Cumference

2:57 AM

Some describe the universe as being on the surface of a sphere — here, we'd use Riemannian geometry.

Some describe the universe as being completely flat, others describe it as saddle shaped

@heather When we say "the shape of the universe", we can think of it like this: if you were to pick three coordinates in space, and draw a triangle connecting those points, how many degrees would the triangle have?

If it's more than 180, our universe is shaped like the surface of a sphere (meaning our universe can only be finite in size)

heather

hmm, i dunno, let me think about it.

Sir Cumference

If equal to 180, than our universe is flat

If less than 180, our universe is saddle-shaped

heather

maybe less than 180? would inside of a sphere -> saddle?

that makes sense, the shape seems similar.

Sir Cumference

@heather I'm sorry?

Skyler

@SirCumference ever heard of AdsCFT?

Sir Cumference

3:01 AM

@Skyler No, I don't know about that stuff

heather

i've got to go, sorry

Skyler

@heather adios heather

Sir Cumference

adios

heather

but what i meant was if the universe was "inside" a hollowed out sphere, it would be like a saddle shaped universe, right?

Skyler

@SirCumference its an interesting "trick" that could have big meanings

heather

3:02 AM

good night, anyway. =)

Sir Cumference

@Skyler String theory trick?

@heather As far as I know, that'd actually have more than 180°

If my understanding is good

Skyler

@SirCumference basically quantum gravity (by ways of Anti deSitter spaces) can be mapped to quantum field theory

Sir Cumference

@Skyler Oye, quantum gravity?

Isn't that dead?

Skyler

All I know is that people are mapping the behavior of black holes onto semiconductor problems and finding solutions (that work)

and bringing it back over to astrophysics

its formulated in string or m-theory iirc, though im not sure what its limitations are

and if other forms of it exist

Skyler

4:40 AM

hey guys, is there a nice piece of software that i can just crack open, create arbitrary some geometries, and test those surfaces as mirror faces

Anon234_4521

Can anybody explain how it's even possible to find the electric field between two infinite sheets of known charge, some known distance from each other? It seems that sigma relies on area and I don't know how to handle that for an infinite area. Do I need to do something special?

Sir Cumference

5:56 AM

Thank god for coffee

John Rennie

6:17 AM

@SirCumference Amen brother

Skyler

6:30 AM

@Anon234_4521 is this in empty space?

otherwise

John Rennie

@DanielSank that's a bit harsh. Because I prefer coffee to tea doesn't (necessarily) mean the British have zero taste for food whatsoever. I have British friends who like tea, and some of them appear to be sane :-)

Anon234_4521

@Skyler You could say the two charged infinite sheets are in empty, hypothetical space. The charge density depends on area, but the area isn't the whole area of the sheet as I've discovered. That was why the charge density was invented in the first place (afaik)

Skyler

@Anon234_4521 if its a plane you have symmetry in 2 directions so you can think of it as a 1 d problem

then treat the charges as boundary conditions, and define one of those two as your zero reference potential

Anon234_4521

For the purposes of the problem I was given, I could use kinematics to get the electric force and the electric field from there, but I was taking the heavy-handed approach with Gauss's Law, which I haven't read yet. That's why I was having difficulty. Thanks.

@skyler I have a sort-of subsequent question I acquired, which I can't seem to find online. I don't understand why for an infinite sheet of charge, most of the sources I read consider integrating it using rings. Some just plain tell me to consider a cylindrical surface area from it. It doesn't seem to make sense to me.

John Rennie

6:48 AM

@Anon234_4521 if you want to use Gauss' theorem you consider a cylinder normal to the sheet and the answer follows immediately.

If you want to do it the hard way you can integrate the field from rings or strips.

Anon234_4521

Okay, I get it.

thought for food

@JohnRennie what, may I ask, does sanity have to do with taste for food, Sir?

(username excluded, of course)

:-)

John Rennie

There is clearly some correlation. For example only raving lunatics would eat tripe :-)

thought for food

Good point.

::recalls The Silence of The Lambs:: :-/

Ramanujan

7:19 AM

@JohnRennie hi

What are dielectrics?

John Rennie

Morning :-)

Ramanujan

Good Morning :D

in The Periodic Table, 1 hour ago, by Ramanujan

> the electrostatic forces between two charges are inversely proportional to dielectric constant of the medium

I don't understand what it means

John Rennie

A dielectric is anything that can be polarised by an electric field

Ramanujan

Googling :: polarised::

Anon234_4521

Polarization is the type of charge: positive or negative.

John Rennie

7:21 AM

If you put a charge in e.g. a solid then the electrons in the solid will move in response to the electric field of the charge.

Ramanujan

So dielectric is a :solid: which takes any charge?

John Rennie

This movement of the electrons in the solid tends to cancel out the field from the charge so the field isn't as strong as it would be in a vacuum.

@Ramanujan In principle anything, solid, liquid or gas, is a dielectric because the electrons, ions or anything charged in it can move in response to an electric field.

Ramanujan

So when we introduce electric field , charges will move?

And what is dielectric constant ?

John Rennie

In general any material is affected by an electric field to some extent i.e. there charges within it can move in response to an electric charge. Another way of saying this is that the polarisibility is greater than zero.

@Ramanujan If you start with a vacuum, even a vacuum can be polarised slightly due to quantum mechanics effects so it has a dielectric constant that we call the permittivity of free space, $\varepsilon_0$. And this is a constant.

For any material we can define the ratio of its polarisibility to the polarisibility of a vacuum, and we call the the relative permittivity, $\varepsilon$.

The dielectric constant is just the product of the two: $\varepsilon\varepsilon_0$.

The dielectric constant tends to be called permittivity these days, though both words mean the same thing.

Permittivity

In electromagnetism, permittivity or absolute permittivity is the measure of resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how much electric field (more correctly, flux) is 'generated' per unit charge in that medium. More electric flux exists in a medium with a low permittivity (per unit charge) because of polarization effects. Permittivity is directly related to electric susceptibility, which is a measure of how...

Ramanujan

OK,thanks

David Z

7:38 AM

room topic changed to The h Bar: General chat for Physics Stack Exchange (physics.stackexchange.com). For MathJax see meta.stackexchange.com/a/220976 (no tags)

John Rennie

@DavidZ wasn't it the h bar i.e. lower case b?

David Z

@JohnRennie hm, I actually don't know

John Rennie

These things matter!! :-)

David Z

Apr 14 '16 at 8:27, by David Z

room topic changed to The h Bar: General chat for Physics Stack Exchange (http://physics.stackexchange.com/). For MathJax see https://meta.stackexchange.com/a/220976 (no tags)

Anon234_4521

I think it was

David Z

7:40 AM

That appears to be the last name change

prior to the barbeque

thought for food

Hip Hip Hooray!

John Rennie

Ah. Faulty memory on my part ...

thought for food

Thanks @DavidZ

David Z

np

It would be amusing to change the name in this manner for, say, Memorial Day, albeit only meaningful for Americans

John Rennie

@DavidZ I think your meta reply is spot on, and changing the name for a day or two should be fine.

David Z

7:42 AM

Yeah, I don't hate fun that much :-P

thought for food

:D

John Rennie

There is a tendency to become paralysed for fear of upsetting someone, and that's not a great state to be in.

David Z

Agreed

We do need a name for our backup chat room

thought for food

Paralysis from over analysis.

David Z

I'm somewhat tempted by the pun value of "The Bottom Quark" but I think we can do better

Ramanujan

7:48 AM

I just derived null point formula for gravity without help of internet iam happy :D

thought for food

Cool, good job!

Physics Meta

0

Q: How do I access chat?

How do access the chat room to ask a question?

support chat

MartianCactus

10:43 AM

heyo

so i have been making ray diagrams related to light and stuff

one thing that i dont understand is

user129412

Rather off-topic (or at least strange), but I figured you might be interested. A friend of mine (a Historian) is working on old letters by 17th century Dutch politician and also mathematician Johan de Witt. She came across this doodle looking this on the back of one of the letters i.imgur.com/gh3EKOt.jpg and was wondering if I had an idea of what it could be/what he was thinking of. It doesn't look like all that much to me (maybe a lens?) but perhaps it rings a bell for one of you

MartianCactus

why is an image formed when 2 light rays meet each other?

why no 1?

why not 3?

and its just 2 rays meeting, why should an image be formed even with 1 ray?

Secret

technically in a ray diagram, all rays emitted in all directions from the object that is focused by the lens form the image, we just drew two to avoid cluttering

MartianCactus

im talking about a normal / curved mirror

havent studied about lenses right now

so we just drew 2

so if we drew "all" of them

then they would all end up at the same point?

how?

thought for food

Usually one at the top of the image and one at the bottom of the image is sufficient.

MartianCactus

10:49 AM

and how can 2 rays meeting form an image?

2 at the top*

and 2 at the bottom

to make an image

or rather a point of an image

everyone says that you at least need 2 rays for that

but why?

actually for now

i gtg

Secret

3

A: Why do you need at least two rays to form an image?

In this first diagram the two grey rays $OXI$ and $OPI$ are the rays I used to find out where the top of the image is formed. They are called the construction ray and these are usually the only two rays that you see on a ray diagram. However in reality all rays bounded by rays $OWI$ and $OZI$ ...

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