The h Bar

0celo7

4:00 AM

lol

Sir Cumference

@MAFIA36790 WHO TOLD YOU?!

0celo7

@MAFIA36790 AC4 ;)

user116211

One good thing is that it is good to learn how to use Sextant as an astrophysicist.

Sir Cumference

But yeah, we had to learn course and bearing

Two math concepts I will never use in my life

user218912

you went to a bad school.

user116211

4:01 AM

Start reading real books, @SirC; it's not late.

Sir Cumference

@bloo Yep

0celo7

SHIT I'm losing

no no no this is not happening

Sir Cumference

user116211

@0celo7 WTH ;/

0celo7

Ha

user218912

4:02 AM

yes, stop reading technical papers and collecting facts you don't really understand.

user218912

and try to really understand physics.

user218912

by reading real books like mafia said.

user116211

^^

Sir Cumference

@bloo But it's just too damn interesting.

Quasi-stars.

user218912

@SirCumference yes, learn them properly

user218912

4:03 AM

after a course in stat mech, GR and astrophysics.

Sir Cumference

All right, where should I start?

user218912

which are all equally interesting.

Sir Cumference

Shouldn't I just keep taking physics classes?

user218912

TONGS NOTES

Sir Cumference

I'd reach your areas soon enough, right?

user218912

4:03 AM

yes

user218912

if you read tong's notes

Sir Cumference

So? All's well that ends well

I meant regarding physics classes

user218912

no.

Sir Cumference

Why not?

user218912

depends what university you're in.

user218912

4:04 AM

if it's a bad university then no you won't

user218912

like the astro grad student

user218912

you'll end up like him

Sir Cumference

Damn...savage

0celo7

I lost

user116211

@SirCumference That's truth.

user116211

4:05 AM

@0celo7 :(

0celo7

badly

I don't know how to recover

@0celo7 :(

oh man

How did you lose?

She pulled the "well I think it's cheating" card

user218912

4:05 AM

@0celo7 what was it about again, it's 12am and my memory is bad.

0celo7

What do I say to that

user228700

I've got a small question regarding statistics again; I've been given the number of goals and the corresponding number of matches for a team A. The variance of another team B is given. To find which team is more consistent, am I to compare their variances? How does this work..?

0celo7

> Do you think it is?

Sir Cumference

@0celo7 "I don't"?

0celo7

NO

@SirCumference Very bad idea.

user218912

4:06 AM

tell her it's because you trust her so much.

0celo7

I did

She put it on me

It was too quick

I don't know how it happened

Sir Cumference

Just talk things out

0celo7

this is so stupid

user218912

@0celo7 so did you break up?

0celo7

nothing even happened

Sir Cumference

4:08 AM

Trying to win might not be the best idea

0celo7

@bloo God no

user218912

idk how relationships work.

user218912

never had one before.

user116211

@bloo Never would like to have one.

Sir Cumference

@0celo7 But yeah, my advice is not to try to win, just talk it out

user218912

4:09 AM

@MAFIA36790 what?

user218912

you like to be forever alone?

user116211

@bloo They are annoying, bothering, wastage of time.

Sir Cumference

@MAFIA36790 You seem like a pleasant man.

0celo7

YES

I FLIPPED IT

HAHA

user116211

@0celo7 WOWW!!!

0celo7

4:10 AM

THE MASTER HAS RETURNED

Sir Cumference

@0celo7 That's...not what I suggested....

user116211

@0celo7 Did you use Trump Card?

Sir Cumference

@MAFIA36790 ...Really?

0celo7

@MAFIA36790 I pulled the "you're being unfair" card

user116211

@0celo7 YESSS!!!

user218912

4:11 AM

@MAFIA36790 so you're gonna die alone?

0celo7

@MAFIA36790 Seriously?

user218912

weird wifi is still on.

0celo7

holy it's 12:15

Sir Cumference

Holy crap it is

It was like 10:00 a minute ago

user218912

I did absolutely nothing today.

user218912

4:16 AM

I was just lying down browsing the internet all day.

Sir Cumference

@bloo I checked out my best friend's school

Got to talk to one of the astronomers for an hour or so

Wouldn't dare do that at my school

user218912

@SirCumference still don't want to tell us what university you're at?

Sir Cumference

@bloo Rather not

user218912

why though?

0celo7

Ok. I lost

Sir Cumference

4:17 AM

But yeah, I'm afraid they'll mention to my professor "Oh this kid's so goddamn annoying"

"Nonstop questions"

user218912

@SirCumference nobody will do that, we're all friends here.

user218912

and also how will they know who you are?

Sir Cumference

@bloo I meant the astronomers

user218912

i mean the university.

user218912

why don't you want to tell us?

user218912

4:19 AM

what are you scared of?

Sir Cumference

I don't like to disclose much info about myself online

0celo7

I won, but I lost

user218912

it's anonymous info though.

Sir Cumference

@0celo7 What happened?

0celo7

Not a good situation

Sir Cumference

4:19 AM

@bloo No info is anonymous.

user116211

@bloo No comments

0celo7

@SirCumference She apologized, but not in a good way

user218912

@SirCumference yes because you're anonymous

Sir Cumference

@0celo7 uhh, so is that good or not good?

user116211

@0celo7 Then , DON't accept ;(

user218912

4:20 AM

we don't know who you are.

0celo7

Not good

Sir Cumference

@bloo I'm not anonymous if I disclose my information...

user218912

that's like me saying I go to X university.

user218912

it doesn't matter what I say

Sir Cumference

Sorry, but I'm not going to say much.

I have reasons.

user218912

4:22 AM

nobody can find you based off of sircumference.

Sir Cumference

Anyways, I really need to go to sleep

user218912

unless you use that name for your university id.

user218912

and such.

user218912

which would be really dumb btw.

0celo7

...

::changes university ID::

user218912

4:22 AM

lol

0celo7

yikes

you can find my freaking office by looking hard enough on google

don't raep me

user116211

0

Q: 4-d VOLUME ELEMENT IS INVARIANT TO LORENTZ TRANSFORMATION

How to show that a four dimensional volume element dx dy dz dt is invariant to Lorentz transformations?

0celo7

@MAFIA36790 do you seriously not want anyone?

Sir Cumference

@0celo7 I don't know why you would tell us that

@0celo7 lol

user116211

Senfding the mafias to kill that damn CAPS user

0celo7

4:26 AM

@SirCumference you won't know how to look hard enough

user116211

@0celo7 nay; no interested.

user218912

@0celo7 I looked really hard and found nothing.

0celo7

WTH!??!

Sir Cumference

@bloo Bit creepy, tbh...

0celo7

^^^^^

user218912

4:27 AM

@0celo7 because I wanted to test out what you said.

user218912

...

Sir Cumference

All the more reason to stay anonymous

0celo7

what did you find

Sir Cumference

;)

user218912

@SirCumference 0celo7 told us his real name though.

Sir Cumference

4:27 AM

@bloo It's not ocelo?

0celo7

I did????????

user218912

I didn't search "0celo7's office"

Sir Cumference

(kidding)

user218912

seriously?

0celo7

@MAFIA36790 Why not?

Are you a guy or a girl

Sir Cumference

4:28 AM

@0celo7 Welp, smart move...

user116211

@0celo7 boy...

Sir Cumference

@0celo7 Isn't this a bit personal?

0celo7

mb

I'm curious

user116211

@bloo wants to stalk @0celo7...

user218912

no.

0celo7

4:29 AM

yes

Sir Cumference

maybe

user218912

wtf?

user218912

I'm not a stalker.

user218912

and 0celo7 is older than me.

Sir Cumference

@bloo We're messing around with you.

0celo7

4:30 AM

ok I have two courses of action

Sir Cumference

In seriousness, though, I really oughta go to sleep

'Night

user218912

@0celo7 wow this whole time you were assuming mafia's gender??? xD

0celo7

either I say that after some thought I agree with her

Sir Cumference

@bloo I assumed Mafia was a guy

user218912

lol

0celo7

4:31 AM

ok that's basically my only option.

Sir Cumference

Wait, can you change your name for only one SE site?

0celo7

well, first time I've ever lost an argument

user218912

@SirCumference didn't you or someone else ask that a few days ago?

Sir Cumference

@bloo Yeah, got no answer

user218912

@SirCumference yes you can.

user218912

4:32 AM

just click "save for only this community"

Sir Cumference

That's so freaky

0celo7

ok muchachos I am going to sleep

Sir Cumference

Crap

@0celo7 Same. 'Night

user218912

nooo don't leave me

user218912

i have wifi!!!

user218912

4:33 AM

...

user116211

.....

user116211

Anyways, gave a threat call:

user116211

What pleasure do you get by writing the title switching on the CAPS LOCK? It doesn't emphasize anything; on the contrary it's a sort of yelling and doesn't increase the readability at all. Also, don't use soft-question unnecessarily. — MAFIA36790 2 mins ago

0celo7

@bloo You know it's true.

@MarkusKlyver Yes, because every $4$-volume can be built out of little cubes. — knzhou Sep 29 at 21:55

This triggers me @knzhou

Sir Cumference

Wait

Shoot, is it "for all intensive purposes" or "for all intents and purposes"?

user228700

4:45 AM

@SirCumference The latter.

user116211

4:55 AM

WTH is that:

user116211

0

Q: Gauss law or gaussian surface of electrical fields

Is it possible to take photograph of this or is this something I only discovered how to do ..I cant find any pictures to reference mine...

gauss-law

user116211

?

user116211

Morning @JohnRennie.

John Rennie

Morning

user228700

Morning Sir :-)

user228700

4:58 AM

Is it possible for one to hide their messages here so that it's visible only to some people?

user116211

@Kaumudi No.

user228700

Then what's up with this:

user116211

Which one?

user228700

I can't see even one of bloo's messages.

user116211

5:01 AM

@Kaumudi You might have ignored bloo.

user228700

@MAFIA36790 Wtf? Without my knowledge?!

user116211

@Kaumudi Might have been accidentally clicked.

user228700

Stupid phone. Yes, I'd accidentally clicked. Thanks.

user116211

I never use phone other than only calling and emergency-browsing.

user228700

I see. I look up everything on my phone while studying. I use the SE app too.

user116211

5:06 AM

Mobile Chat is bleh...

user116211

Moreover there is no app for my Windows phone.

user228700

@DanielSank: Hi :-) Does ur phone give u notifications from the SE chat rooms on time? Mine doesn't :/

user228700

@MAFIA36790 Ah, OK...

user116211

1 hour ago, by DanielSank

Bye, everybody.

user228700

Riight.

user228700

5:16 AM

Anyway can u help me with that statistics question?

user116211

Which one?

user228700

1 hour ago, by Kaumudi

I've got a small question regarding statistics again; I've been given the number of goals and the corresponding number of matches for a team A. The variance of another team B is given. To find which team is more consistent, am I to compare their variances? How does this work..?

user116211

@Kaumudi yes.

user228700

How does that work..? What is the relationship b/w variance and consistency? If the variance is larger, is it that their goals are mostly scattered and hence, not consistent?

user116211

@Kaumudi Didn't you find the variance?

user116211

5:19 AM

@Kaumudi kinda.

user228700

@MAFIA36790 OK..? What's the better way to think about it, then?

John Rennie

@Kaumudi the question is a bit vague, but I'd guess the word consistent means they score the same number of goal every match. If so then the team with the lower variance is the most consistent.

user116211

Are you trying to find between the two datas, which one is consistent?

user228700

@JohnRennie Yes, OK. (I was just about to ping you! :-D)

user228700

@MAFIA36790 Yeah.

user116211

5:22 AM

For that, you need theory of attributes.

user228700

@MAFIA36790 Nooo, never mind. JR's answer clears it right up!

user116211

Consistency has a rigorous definition, btw.

user228700

@MAFIA36790 What is that..?

John Rennie

@MAFIA36790 it does?

user116211

@JohnRennie yes, when you try to find consistency of data.

user116211

5:24 AM

@Kaumudi I don't think it is required in your problem, though.

user228700

Okay!

John Rennie

@MAFIA36790 I've never come across consistence as a term in stats, though that proves nothing as my stats knowledge is pitiful. What you describe sounds more like correlation.

user116211

@JohnRennie kinda right, though.

zed111

Hi, does applying a 1.5 Tesla magnetic field to hydrogen atoms make all of the protons line up? @JohnRennie

John Rennie

Hi Zed. I have no idea. Have you calculated the energy difference between the aligned and unaligned states and compared it to kT?

user228700

5:32 AM

@JohnRennie: What's the difference b/w the terms indestructible and indivisible, when speaking od atoms..?

user228700

I Googled this but to no avail :-(

John Rennie

@Kaumudi neither of those are strictly defined terms in physics, so the meaning is likely to depend on the context.

user228700

@JohnRennie OK, what did Dalton mean when he said "Atoms are indivisible and indestructible" in his postulate..?

John Rennie

Aha! Dalton didn't know that atoms have an internal structure. He thought they were a fundamental object that existed for all time, so it couldn't be created or destroyed, and couldn't be subdivided into its component parts, so it was indivisible.

user228700

"Couldn't be created or destroyed"=Indestructible?

John Rennie

5:36 AM

Indestructible literally means cannot be destroyed

user228700

Hm, yes. OK.

John Rennie

Obviously Dalton didn't know about fusion or fission, so he was talking about chemical reactions.

user228700

Yes, OK :-)

John Rennie

He really meant that atoms cannot be destroyed in a chemical reaction.

DanielSank

@Kaumudi My phone? No... my phone never tells me anything about physics.

John Rennie

5:38 AM

So in any reaction the same atoms come out as went in, just rearranged differently.

Which was a startling insight for the time!

DanielSank

@JohnRennie Pfffft. That's why you think. Apparently you've never tried alchemy.

user228700

@DanielSank Lol, no, if someone pings you, do u get notifications immediately?

DanielSank

@Kaumudi Chat room pings take a while to show up in my SE notifications inbox.

user228700

@JohnRennie Yes! OK :-)

DanielSank

I'm not sure about the mobile chat page, as I don't use it too much.

user228700

5:39 AM

@DanielSank No, on the notifications bar on ur phone, I mean.

user228700

Also, @JohnRennie: Is all this correct:

John Rennie

@DanielSank I'm sure Dalton would be amused to learn we can now make gold :-)

user116211

@JohnRennie All alchemists would be amused.

user228700

(Don't be alarmed at my stlye of note-taking; I do it like this so I feel like revising them, later on and oddly enough, it works!)

DanielSank

@Kaumudi I never get any system level notifications on my phone from SE. Not sure how I'd set that up.

John Rennie

5:41 AM

>Not sure how I'd set that up
Install the SE app presumably ...

DanielSank

^ Did

John Rennie

Damn, experiment trumps theory again :-)

user116211

Why do they don't make app for Windows?

user116211

Damn ;(

user228700

@DanielSank: I've installed the app and notifications do arrive...eventually.

user116211

5:42 AM

FWIW, this is basically the same as this other question. — Kyle Kanos 10 hours ago

DanielSank

@MAFIA36790 Presumably because there's already a rather nice webpage.

user116211

Kyle is still active :)

user228700

So yes, is all that correct? I did a lot of Googling to figure those things out but some posts on S.E don't agree with those definitions. That's why I asked.

DanielSank

@Kaumudi I'm looking in the mirror! I took my university notes in color.

user116211

5:44 AM

I never use Rainbow pen.

John Rennie

@Kaumudi that all looks fine.

Did you need any of it explained?

DanielSank

@MAFIA36790 I used the colors for different things: section headings, important results, etc.

user116211

@DanielSank I use blue pen only and for headings I mark # before the topic.

DanielSank

@MAFIA36790 So you take notes in markdown?

user116211

@DanielSank yes.

user228700

5:46 AM

@DanielSank Cool :-) I was a bit hesitant on using colors when I get to college next year but I feel more OK with the idea now. I'll definitely continue in college :-P

user228700

@JohnRennie No, it's just that some of the definitions don't match with those in some posts on S.E, so I was making sure...

John Rennie

@Kaumudi they don't?

user228700

@JohnRennie No :/ All these different terms for mass confuses people a lot, so it's possible that the OPs were unsure themselves.

John Rennie

Well atoms are complicated things. For example the mass of an atom isn't equal to the masses of the protons, neutrons and electrons in it.

user228700

@JohnRennie Yeah, Ik :-)

DanielSank

5:50 AM

@JohnRennie It's close enough though!

user228700

I'm looking up a lot of my old doubts so I might be asking quite a few of them today, albeit, really small ones. Is that OK, @JohnRennie?

John Rennie

Yes, I'm kind of hanging around drinking coffee for the next 40 minutes.

user116211

@JohnRennie Weekends ;P

user228700

Hm, I wonder how much coffee u consume everyday.

DanielSank

The binding energy of an electron in the ground state of a hydrogen atom is one hundred-thousandth of the mass of an electron.

John Rennie

5:52 AM

@MAFIA36790 that's actually my normal routine. My first big job of the morning is at 07:30 UK time. Before than I just do a few checks to make sure no servers have died horribly overnight.

DanielSank

That's one hundred-millionth the mass of a proton.

user116211

@DanielSank There is a pretty nice discussion on it in Feynman Lectures Vol 2; some of the last chapters AFAIR.

user116211

@JohnRennie WoW! Nerd life.

John Rennie

@DanielSank it's experimentall detectavble though. The mass measurements of the proton, electron and hydrogen atom are just accurate enough to measure the binding energy to about 20% precision.

user228700

@MAFIA36790 Dude, do u have a time turner or something? Or wait, did u not at all attend school in 11th and 12th?

user228700

5:54 AM

OK, so exactly what's the difference b/w diffusion and expansion..?

user228700

(BTW, you may rest assured that for every one of these doubts, I've done a ton of Googling before.)

user116211

@Kaumudi I must I didn't go to school at all except my practical classes. The teachers were quite kind to let me study in my home.

DanielSank

Music show and tell

John Rennie

@Kaumudi they are completely different!

user228700

@MAFIA36790 Weird school :/

user228700

5:56 AM

@JohnRennie OK..?

John Rennie

@Kaumudi expansion is just the change in volume of some object e.g. due to a temperature or pressure change.

user228700

OK...

John Rennie

diffusion is the net motion of an atom/molecule/whatever in a medium due to random thermal motion.

user228700

But, I mean, the difference isn't that clear to me. Both mean the motion of molecules, right? Such that their volume expands...

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