The h Bar

skill patrol

4:24 AM

What do you suppose these lines mean (without looking it up)?

0celo7

Easy.

skill patrol

?

0celo7

Darth Vader's breathing slits.

skill patrol

:D

0celo7

@ACuriousMind Is there a category of integral domains? Euclidean domains?

skill patrol

4:26 AM

Hint: think "trademark"

0celo7

World trade centers?

skill patrol

Nope

0celo7

i give up

@skillpatrol people have been raiding the building where my office is in

they made off with $20,000 in microscope related stuff today

@skillpatrol we need armed guards

and armed employees

user507974

5:02 AM

hey gents

skill patrol

5:18 AM

@0celo7 hp

@0celo7 that sounds so...ghetto

hey there @user507974 welcome

ManishEarth

@skillpatrol is that a b and a p?

@skillpatrol oh, I'm an idiot. that's an HP logo

Jester Tran

5:38 AM

Hi, what is the best book to master probability?

user507974

5:58 AM

whos afk?

(does anybody else enjoy asking that question)

skill patrol

6:19 AM

you got it @ManishEarth

kevin Tah N.

I was gifted $100 to buy a book. What is the best text I could learn a lot of Theoretical Physics from. I have an aweful Math and Physics background. It will be nice to buy something that can teach me QM and EM and may be even more . . . qft and stuff really well

*awful

user507974

why buy one book when you could buy 5

kevin Tah N.

That sounds like a plan

Actually if I have a good QM text, EM text and Statmech text I will be super happy. I want a text that assumes I am the dumbest person on the planet, has diagrams and explicite calculations

user507974

a sad truth is that at some level each book kind of sucks

griffiths is a baby's intro to QM but really doesnt use Dirac notation enough or make you understand the underlying linear algebra, but is a great starting point

Valentin Tihomirov

6:34 AM

Why doesn't local realism imply superdeterminism?

user507974

6:57 AM

Does anybody have an opinion on Applied Analysis by the Hilbert Space Method by Holland

@kevinTahN. the book im asking about inthe last comment is something to look at ve4ry likely

im just trying to figure out if it is below my level now

David Z

7:49 AM

@kevinTahN. if you were the dumbest person on the planet I would strongly advise you against spending $100 on a physics textbook :-P

user507974

@DavidZ any input on the book im looking at

David Z

The Holland book? No, never heard of it

user507974

ive read reviews that literally call it the perfect book

David Z

@kevinTahN. For beginners, I recommend Griffiths for QM and Schroeder for stat mech. I'm not sure about E&M. Griffiths has written a pretty good intermediate E&M book though.

Slereah

Hey hey

Isn't Jackson the standard EM

user507974

7:52 AM

@Slereah at grad

hmm, 3 users simultaneously disconnected

David Z

The standard E&M sequence would go something like Purcell (intro), Griffiths (intermediate), Jackson (advanced)

or at least that's what I've used. Purcell takes a certain kind of reader to appreciate, though.

user507974

@DavidZ whats the intermediate QM, shankar?

sakurai?

Slereah

I am trying to do some Peskin by hand, but

due to some health issues

I'm having trouble to use a pen

Blisters on the fingers

user507974

@Slereah perfect excuse to tex hw

David Z

@user507974 I think people have different opinions, and there isn't one that's considered completely standard the way Griffiths' book is

user507974

7:57 AM

@Slereah nvm

@DavidZ which is weird, given how pedagogically speaking griffiths has some major oversights

David Z

I don't think it's weird. Or at least, not unexpected.

user507974

@DavidZ true

David Z

Griffiths' book is an intro-level book; whatever its characteristics, it doesn't affect whether there would be a single standard book at the next level.

user507974

i meant its weird that griffiths is so standard

i feel like its just missing so much that is important to get QM

David Z

I think the reason it's so standard is precisely because it leaves out so much. Otherwise it would be overwhelming to beginners.

user507974

8:03 AM

i dont know, i almost feel like if i didnt supplement it with other books i would barely be able to do anything past the basic 3-4 potentials and maybe perturbation theory (and understand really what im doing)

heck the understanding part may be asking too much already

i remember my classmates dying when the prof for my 2nd qm course started using dirac notation and we did things like spin additions

@DavidZ did they get rid of the edit button here btw

it use to have a 5 minute limit on edits

@JesterTran depends on what you want with probability...

David Z

@user507974 yes, exactly, that's the point

@user507974 not as far as I know. There's still a time limit, but also you can still edit messages within the time limit.

user507974

@DavidZ i think they lowered it to 1 minute

@DavidZ but that kind of means the entire middle of the book isnt really learned, just chapters 1-3 and 9

David Z

Oh, maybe I misunderstood what you meant a bit.

Well, everyone has a different method of learning. Sometimes you need to supplement a book with other books, and that's true for somebody no matter which book is being used.

Jester Tran

8:29 AM

@user507974 I need to master basic probability theory. i just want to think probabilistically

@user507974 It's my weakest area, including combinatorics, so I wish to master them

user507974

@JesterTran i liked the first chapter of this pchem book you probably have in your library

i think it was szabo

well i just got one of the landau lifshitz books for like $12

Jester Tran

8:45 AM

@user507974 sorry, pchem?

and I only have Probability Theory: A Concise Course

user507974

@JesterTran physical chemistry, its kinda like chemistries weird cousin to qm and statistical mechanics

if you can check it out and just look over the chapter/appendix on probability stuff i think i liked the explanations in it

Jester Tran

@user507974 I think you got the wrong user!

wait...

ACuriousMind

@0celo7 Well, of course you can restrict the category of rings to those special rings. What morphisms you choose and whether the categorial consideration will be "nice" highly depends on what you want to do, though.

Jester Tran

oh, I will check that out for the probability stuff, thanks

user507974

@ACuriousMind hey acm, hows it hangin

ACuriousMind

8:49 AM

@user507974 It's hanging lazily, still two weeks till the semester starts

user507974

@ACuriousMind what classes?

or were you past classes

ACuriousMind

I'm past obligatory classes, but taking some anyway: "Advanced String Theory" and "Topology of Singular Spaces"

Perhaps more if something catches my eye, I haven't looked into the latest list of classes yet

user507974

@ACuriousMind i saw this video "Hitler learns topology", were you the person who posted it or did i find it somewhere else

Hitler Learns Topology

►

ACuriousMind

Might have been me, but I think I'm not the only one who's posted that to this chat :D

user507974

@ACuriousMind what type of coursework have you been taking in general

obviously id guess previous string theory courses plus all the physics grad basics

ACuriousMind

9:04 AM

As much math as I could get, and in physics mainly all sorts of QFT

Oh, yes, and the intro to string theory, which did not really please me at all, I'm hoping this one will be better :P

user507974

@ACuriousMind i had a bit of that experience with statistical mechanics, so far im hoping this quarter will be more fruitful

ACuriousMind

Oh god my stat mech course was dreadful

user507974

@ACuriousMind basically ive just tried to drill these things into my head in as many ways as possible since i find it really interesting, this would be my 4th course

first one was with a prof whod butcher you if you asked "a dumb dumb" question (aka all questions), then I had a really good prof in a different dep who basically redid the material and got twice as far in the book, then a time consuming and hard phys grad course and now im doing the advanced one

hopefully between all that ill have imprinted something

Valentin Tihomirov

I read about a variation of Bell's inequality, that is put as Psame(A, B) + Psame(A, C) + Psame(B, C) ≥ 1. I wonder. Does it make sense to add up overlapping probabilities? Say, you pull cubes and balls, whether white or black at random. So, P(black) + P(ball) = 1 but does it make sense? When you start testing it, the frequency of P(black or ball) will be .75 < 1, I guess. Will it prove anything?

Jester Tran

anyone know how to access the download for: ypapuapiro.ru/rinuq.pdf

The website is suspicious... all comments are a variation of "good". So there must be some benefit of commenting on this website

Slereah

11:23 AM

feck

students are blasting music at full volume

Can't do any work

0celo7

11:51 AM

@skillpatrol sadly we can't concealed carry on campus :(

Slereah

That's good

Otherwise I'd be shooting at that fucking boombox

ACuriousMind

@Slereah ...why are you on a campus?

Slereah

I work at a university

skill patrol

@0celo7 a university is no place for that sort of thing anyway

high school yes, university no :P

Slereah

Well you have to kill the phonies

skill patrol

11:57 AM

where?

Slereah

Possible photo of @0celo7 :

skill patrol

lol

ACuriousMind

@Slereah Ah, didn't know that, thought you worked for some software developer

Slereah

Well the university does some software stuff

I don't teach or anythin'

skill patrol

would you ever like to?

Slereah

12:00 PM

Programming? Fuck no.

Physics sure

Well

Fancy physics

I don't want to teach bloody classical mech or w/e

0celo7

Not even Arnold classical mech?

Slereah

is it the one with bundles

0celo7

@Slereah Yes, I've been told I look like Dylan Roof at times.

Same disposition, world view, etc.

@ACuriousMind Indeed.

@ACuriousMind Must one define the one of a ring from the left and the right in a noncommutative ring?

Slereah

Isn't there a theorem that states that neutral elements are the same on both sides

0celo7

@skillpatrol Huh? How else are we going to shoot intruders?

Slereah

12:03 PM

Or is that for 0

0celo7

That's for zero.

Slereah

Hm

0celo7

Because you can distribute on the left or right

ACuriousMind

@0celo7 I think so, yes

skill patrol

@0celo7 that is the security's job

skill patrol

12:16 PM

do they still have koenig's in germany? @ACuriousMind

hi @yuggib

ACuriousMind

I don't know what a "koenig's" is supposed to be

skill patrol

German for king

ACuriousMind

...you're asking me if Germany has a monarchy?

skill patrol

yup

ACuriousMind

Uh, no. We haven't been a monarchy since the first World War.

0celo7

12:28 PM

What about Angela?

She thinks she's the queen B

What about Angela?

@skillpatrol They won't shoot the intruders

skill patrol

@0celo7 who is Angela?

ACuriousMind

He means Merkel, our chancellor.

(Note that the chancellor is not even head of state, so she's pretty far from a monarch)

skill patrol

noted

0celo7

@ACuriousMind No, i mean Angie

The last name is a sign of respect

Loong

@ACuriousMind the Chancellor is actually the number three in the order of precedence.

0celo7

12:33 PM

wtf

how did you know we were talking about German stuff

ACuriousMind

@Loong Isn't it fourth? I thought the presidents of both chambers of parliament come between chancellor and president.

Loong

German order of precedence

The German order of precedence is a symbolic hierarchy of officials in the Government of Germany used to direct protocol. It has no official status, but has been established in practical use. The Federal President (Bundespräsident) The President of the Bundestag (Bundestagspräsident) The Chancellor (Bundeskanzler) The President of the Federal Council (Bundesratspräsident), also acting as deputy to the President The President of the Federal Constitutional Court (Präsident des Bundesverfassungsgerichts) == References... ==

ACuriousMind

Huh, indeed.

skill patrol

this looks interesting

Year of the Three Emperors

The Year of the Three Emperors, or the Year of the Three Kaisers, (German: Dreikaiserjahr) refers to the year 1888 during the German Empire in German history. The year is considered to have memorable significance because of the deaths of two German Emperors, or Kaisers, leading to a rapid succession of three monarchs within one year. The three different emperors who ruled over Germany during this year were Wilhelm I, Frederick III, and Wilhelm II. The mnemonic “drei Achten, drei Kaiser” (English: "three eights, three emperors") is still used today in Germany by children and adults alike to learn...

0celo7

I do not understand the German political structure.

It's so complicated, why not use the American model?

skill patrol

12:37 PM

because they're not american

0celo7

Our system won a world war. Two, even.

The Germans lost both. Very sad.

ACuriousMind

...you do realize we changed the systems after each war?

skill patrol

the "system" didn't win the war

ACuriousMind

Also, that^ :P

0celo7

@ACuriousMind You failed twice. Why would the third one be any better?

skill patrol

12:39 PM

trolling alert

0celo7

Proof?

skill patrol

go back to Einstein and The Evidence

ACuriousMind

I genuinely can't tell anymore if you're joking or actually such a nationalist

skill patrol

he mixes and matches

0celo7

@ACuriousMind An AnCap nationalist?

I don't think even I could handle such doublethink.

@skillpatrol All I have is this to dispatch the science building robbers

We need properly armed employees!

skill patrol

12:43 PM

why?

0celo7

> to dispatch the science building robbers

@skillpatrol BTW, fine knife.

I got it on the cheap in a local store

skill patrol

how much?

0celo7

@skillpatrol wait, that's the wrong blade size

Mine is sub 3".

ACuriousMind

Strangely enough, no one at our universities is armed, and yet we don't get robbed.

0celo7

@ACuriousMind I would comment but the PC police would attack me.

ACuriousMind

12:46 PM

I have no idea what that is supposed to mean.

0celo7

Such innocence

skill patrol

anything over $50 is a waste

0celo7

@skillpatrol It was way over $50

skill patrol

waste

0celo7

Shit, are there any decent knives for that little?

skill patrol

12:48 PM

you don't need a knife, when you have street smarts

0celo7

Hahahahahahah

When have street smarts killed an intruder

This isn't Home Alone

skill patrol

just call the cops

911

0celo7

Yeah, and wait 15 minutes for them to stroll by

skill patrol

isn't your own safety worth the wait?

that^ my friend is street smarts

0celo7

What?

ACuriousMind

12:54 PM

You have a worrying obsession with killing intruders. Attacking trespassers or thieves with lethal force is a disproportionate reaction.

0celo7

@ACuriousMind No!

skill patrol

you never know how dangerous they may be

0celo7

Any crime that is not a crime of passion should be capital

@skillpatrol Why do you think I've played so much Splinter Cell

skill patrol

this is NOT a game

0celo7

@skillpatrol Is that a meaningful statement?

Does it matter if this is a game or not?

What do you even mean by that?

@ACuriousMind It's not worrying unless you plan to trespass in my office or home?

skill patrol

12:58 PM

what if they pull out a gun and blow your head off?

0celo7

That's why I need to be similarly armed!

skill patrol

game over

0celo7

You're making my case for me.

skill patrol

then it is just an arms race

0celo7

Huh?

Are you saying they'll roll up to SERF (Science and Engineering Research Facility) in a tank?

skill patrol

1:00 PM

who can draw their gun faster

why not just let the cops handle it?

0celo7

@skillpatrol I've been taking professional shooting lessons for years. I don't think these robbers are Delta operators

@skillpatrol Justice.

Brb lit class

cya later

@skillpatrol \o

@yuggib o/

how are you doing?

1:03 PM

fine thanks, how are you?

yuggib

been quite away lately (I had to change country another time, fill in all the bureaucratic forms, etc...standard postdoc life)

but I'm fine!

skill patrol

did you see that game on monday?

yuggib

which game?

skill patrol

Villanova vs. North Carolina: Final minutes of national title game

►

yuggib

no I missed it

skill patrol

1:08 PM

intense drama at its finest

yuggib

I'm watching right now ;-)

nice!

(apart if you are a tar heel)

skill patrol

the tar heels were 3 point favourites

what a difference 4.7 seconds makes

user116211

1:29 PM

@yuggib: o/

user116211

I was missing you.

user116211

I was seeing the derivation of Coriolis force in French's book:

yuggib

@MAFIA36790 \o

@MAFIA36790 from Coriolis' original?

user116211

@yuggib Don't know.

user116211

1:35 PM

I'm having some problem in conceiving the proof....

yuggib

it doesn't seem very french...

ACuriousMind

@yuggib A. P. French.

yuggib

@ACuriousMind ah...

a french book would be more appropriate :-D

user116211

He says in inertial frame $S$, the vector $\rm{CD}$ changes by $\mathrm{DE}= \omega\times \mathrm A \Delta t $...

user116211

But then he says, in the rotating frame $S',$ this change doesn't occur (okay, got it)

user116211

1:40 PM

But instead there is a change in $\rm{CD}$ by $\rm{EF}= \Delta\mathrm A_{S'}$ as shewn in the pic. (swallowed it... )

user116211

The total change in $\rm{CD}$ in the inertial frame $S$ is given by the vectorial addition $$\mathrm{DE}+\mathrm{EF}$$....

user116211

But how can it be?

user116211

Meant to say why the change in $\rm{CD}$ given by $\rm{EF}$ in $S'$ should be added to $\mathrm{DE} $ to get the total change in $S\;?$

user116211

If it hadn't rotated, the change in $S$ would be simply $\rm{EF}$ that is same as $S'\;?$

user116211

I'm not getting that.

barrycarter

1:45 PM

Save a dollar, spend a penny, bring to me the soul of Rennie. @JohnRennie that is.

0celo7

2:00 PM

@skillpatrol I wonder if carrying my Bowie knife is legal?

skill patrol

ask a cop

@0celo7 here

John Rennie

2:19 PM

@barrycarter Hi Barry White, er no, hang on ... hi Barry Gibb, nope still too musical ... let's try hi Barry Carter

barrycarter

Hey, I love the BGs :P

@JohnRennie I think I may have figured out one of our issues: since we have both a spaceship and Earth in the same frame, we may need an affine transformation instead of a linear one.

John Rennie

The Lorentz transform is affine isn't it?

Actually I was going to ask you something ...

Slereah

Isn't it linear

barrycarter

@JohnRennie No, it's linear, since it's a matrix.

John Rennie

Re your comment about a canonical question about basic of relativity, I posted three time related questions:
[What is time](http://physics.stackexchange.com/questions/235511/what-is-time-does-it-flow-and-if-so-what-defines-its-direction)
[What is time dilation](http://physics.stackexchange.com/questions/241772/what-is-time-dilation-really)
[Twin paradox](http://physics.stackexchange.com/questions/242043/can-anyone-explain-the-twin-paradox-properly)

I wonder if extra answers could be added to one of these to discuss failure of simultaneity etc.

Odd, those links didn't work ...

barrycarter

2:23 PM

@JohnRennie If we had a linear transform from AMT to NMT and another linear transformation from AMT to Earth, the difference of the two transformations would be a shift, which is impossible for a linear transform.

ACuriousMind

@JohnRennie Linebreaks make markup not work.

You can either have fancy formatting or linebreaks, not both

barrycarter

@JohnRennie I think we need some sort of glue or meta page... something that combines the various issues of relativity, because my concern is that people understand one aspect and not another, resulting in confusion.

John Rennie

@ACuriousMind Goddamn SE spoiling my fun :-)

Anyhow linear transformations are affine aren't they?

barrycarter

@JohnRennie For example, solve a simple problem for an observer moving at 0.8 c or something, and another for simple acceleration and deceleration... and make these canon problems general enough that others can plug and chug their own values.

@JohnRennie Well, yes, but affine aren't linear. Affine can shift the origin.

John Rennie

Non-linear transformations are required in relativity for dealing with accelerated motion

barrycarter

2:26 PM

@JohnRennie Linear transformations must map the origin to the origin.

ACuriousMind

The "affine" relativistic transformations are the Poincaré transformations, but since those are just Lorentz + translations we usually don't talk about them in basic relativity as they have no interesting "relativistic" effect.

John Rennie

OK, but I'm not sure I see the need for anything beyond the Lorentz transformations as long as acceleration isn't involved.

And once acceleration is involved things get rather sticky quite quickly

barrycarter

@JohnRennie Well, how would you translate between NMT and Earth? What's the transform there?

John Rennie

t_NMT = t_Earth, x_NMT = x_Earth + 10

barrycarter

Hmmm, my render is broken

That's not a linear transformation though.

John Rennie

2:29 PM

As ACuriousMind says, we usually ignore translations on the grounds they are trivial

barrycarter

There's no matrix that will give you that transform.

Because it translates the origin to 0, 10

@JohnRennie Agreed that they are trivial, but necessary in this case.

In other words, you can't have a linear transform for AMT -> NMT and a linear transform from AMT -> Earth that have the same t=0.

John Rennie

This is the purist streak that mathematicians are cursed with coming to the fore again. Anything that leaves the axes parallel is irrelevant as far as physicists are concerned.

barrycarter

@JohnRennie OK, but the point being: Lorentz transforms are always linear.

@JohnRennie You need something more than them to solve this problem.

John Rennie

You aren't getting this: physicists DON'T CARE :-)

barrycarter

perpendicular?

@JohnRennie Deep down, I always knew that was true...

John Rennie

2:32 PM

@barrycarter x parallel to x' and t parallel to t'

barrycarter

Oh, OK.

John Rennie

All the weird shit in relativity is because the axes rotate relative to each other

barrycarter

Anyway, I think that allowing for that little bit of affinity (?), the problem should work out.

affineness?

John Rennie

You've yet to convince anyone but yourself that there is a problem

barrycarter

@JohnRennie Really? You seem fairly confused yesterday.

John Rennie

2:34 PM

Incidentally I'm cooking a rissotto so if things go quite for a moment I'm in the kitchen adding more stock

barrycarter

Romanians taste better.

John Rennie

@barrycarter you have that effect on people

barrycarter

@JohnRennie Well, in person, yes, but I didn't realize my charisma translated to chat.

John Rennie

I can only pray we never meet in person or I will forget how to walk and talk

barrycarter

@JohnRennie Usually, the walking returns after a couple of days of stiffness.

John Rennie

2:36 PM

:-)

barrycarter

@JohnRennie But, OK. I think that was the fundamental issue -- I was trying to find a linear transform for both AMT -> NMT and AMT -> Earth with the same t=0, and that's impossible.

John Rennie

OK, yes, I agree.

barrycarter

Kind of wish you'd said that earlier when we were trying to find those transforms :)

John Rennie

It never occurred to me someone would prefer an algebraic approach to looking at a spacetime diagram

barrycarter

Really????

John Rennie

2:38 PM

Have I mentioned that relativity is a geometric theory?

barrycarter

There's nothing wrong with diagrams, but they're crutches.

@JohnRennie LOL :) Yes, and thus, a matrix is involved.

Graphs are what you draw for students.

The good stuff is always in the pure math.

John Rennie

Intellectually I accept that mathematicians have a particular perspective on this ... but in my heart I believe you're all barking mad.

barrycarter

To be fair, you did say we didn't need two transforms, but you never said it was impossible to find two transforms.

Valentin Tihomirov

I see in the tutorial that Phi = 1/sqrt(2) (\vec 0 + e^ai \vec 1). The tutorial says that square of vector projuection upon its basis vector must give the probability and all probabilites add up to 1. I see that projection of Phi to \vec 0 = 1/sqrt(2) and proj to \vec 1 is e^ai/sqrt(2). Summing the squares, I get 1/2 + e^2ai/2 = (1 + e^2ai)/2. I do not see that it adds up to 1.

John Rennie

@ValentinTihomirov you don't give a link, but presumably 0 and 1 are orthonormal ...

Valentin Tihomirov

2:42 PM

They are by definition

The link is here, on page 13

barrycarter

@JohnRennie Well, I've had an epiphany. Lorentz transforms only work if two observers share an origin at some point. There is no Lorentz transform for two objects at the same velocity at non-zero distance.

(shaking fist) The Lorentz transform doesn't work for v=0 !!!

@JohnRennie Purely theoretical question: if I do write up a canon answer on how to solve simply relativity issues, will you review it?

John Rennie

OK, fair enough.

@barrycarter That would almost certainly be an unacceptable question as it would fall fowl of the worked example policy

barrycarter

If two objects are moving wrt each other in one dimension, they must share an origin at some point in time, even if that time is theoretical. However, if they are NOT moving wrt each other, no such point in time exists.

@JohnRennie Oh, crap, so what I've been suggesting is verboten?

Physics Meta

0

Q: What should I do to get a satisfactory answer?

I am not able to get a satisfactory answer for my question. What should Ido?

John Rennie

@barrycarter Questions should be precisely targetted and identify a concept in physics. So a question about simultaneity failure might be OK, but a question "how to I solve relativistic problems" wouldn't be

barrycarter

2:50 PM

@JohnRennie Well, that's what I was suggesting. A canonical "here's how you work out a relativity problem" so people who ask questions like that can be directed to it.

I am saddened :(

1

Q: Correct resolution of vectors

There's a sum given as an example in my physics textbook which I tried to solve in a different manner but ended up with a wrong answer. Here's a picture of the sum given in my textbook along with the solution that they provided. And here is what I tried to do. I resolved the vectors as shown in...