The h Bar

John Rennie

16:00

@FenderLesPaul You need a physical chemist. Drinking and fighting is traditional for us physical chemists :-)

ACuriousMind

No one here has an algebra fetish. ::nervously glances around::

0celo7

my neighbor is a Pchem prof., she'd kill me in a heart beat

FenderLesPaul

@JohnRennie hehe

gonenc

@JohnRennie didn't get the joke/pun :(

0celo7

@ACuriousMind I want to have an analysis fetish for some reason

but I don't know any analysis

ACuriousMind

16:01

@0celo7 The unknown is always seductive ;)

FenderLesPaul

@ACuriousMind don't you have a poster of Haag's QFT that you pray to every night before sleeping?

Jimself

@ACuriousMind That's why I haven't told you my real name

gonenc

@Jimself in order to be seductive?

Jimself

;)

gonenc

@Jimself I really think that it is Jim

0celo7

16:02

can't flim flam the jim jam

@Slereah would appreciate that

John Rennie

@Jimself I feel traumatised now

FenderLesPaul

0

Q: What is the first topic on mathematics,that an undergraduate physics student must study?

I aspire to become a theoretical physicist. I like to understand about infinite series and so on. Could you please recommend me any book?

gonenc

@Jimself that winking eye...

FenderLesPaul

I didn't know there was an ordering o.o

Jimself

@gonenc nope

ACuriousMind

16:03

@Jimself Oh, you!

Jimself

@ACuriousMind ::giggle::

FenderLesPaul

@obe if you could get Poisson's autograph for me...

gonenc

@Jimself this is getting naughty :D

0celo7

this is really...homoerotic

unless Jim is really a Jimette

John Rennie

@0celo7: category theory? You just advised a budding physicist to study category theory?

ACuriousMind

16:04

@0celo7 You have no proof of gender of either of us

FenderLesPaul

Jimsheisha

gonenc

@0celo7 or one of them is a girl but not both :D

@ACuriousMind are you blonde?

0celo7

@JohnRennie I don't know any, I figure he can teach me

Jimself

@0celo7 why me? why can't ACM be ACMette?

user54412

@0celo7 wikihow.com/Avoid-Being-an-Internet-Troll

ACuriousMind

16:05

@gonenc Dark blonde, but yes

gonenc

lemme be creepy a bit

0celo7

@ACuriousMind that's what you think

FenderLesPaul

@ACuriousMind is actually a cat

John Rennie

@FenderLesPaul A live one or a dead one?

Jimself

::Jim loses interest::

FenderLesPaul

16:06

@JohnRennie is there a difference? :p

gonenc

@ACuriousMind do you wear glasses? :D

0celo7

@ChrisWhite interesting link but I don't see how it's germane

John Rennie

@FenderLesPaul No-one knows :-)

ACuriousMind

@gonenc I get a feeling a picture of me is going to pop up here soon, but yes :D

Shing

@Jimself what do you mean by "programming into relativity"?

gonenc

16:07

@ACuriousMind you should better turn off your cam on your pc though... :P :D

Jimself

@ACuriousMind I live in fear of that every day

0celo7

@ACuriousMind I keep those to myself...

John Rennie

@0celo7 Really. An article to tell a troll how not to be a troll?

Jimself

@Shing intentionally made to fit that condition

John Rennie

Being a troll is accidental?

ACuriousMind

16:07

@gonenc There is none currently connected :P

gonenc

@ACuriousMind nah but it is very easy to verify your gender it is all I'm saying :D

@ACuriousMind nice try :D :P

Shing

@Jimself but I have read that Einstein knows nothing about the michelson morley experiment before his special relativity in my text book

0celo7

@JohnRennie tbh I don't think I have violated any of those (lol double negative)

FenderLesPaul

John Snow knew about Michelson Morley

ACuriousMind

...and he knew nothing

gonenc

16:09

@ACuriousMind and is supposedly dead...

John Rennie

@0celo7 I won't describe any of the regulars hereabouts as a troll.

ACuriousMind

BTW, chat session has begun nine minutes ago, just for general notice ;)

FenderLesPaul

spoileeersss

Jimself

@Shing they observed the speed of light as constant before michelson morely. That's why that experiment was done; to determine if it truly was constant or if it depended on direction

John Rennie

Though we do see them from time to time they tend to be newcomers.

Trolls are rarely willing to put in the hard work required to give good answers.

gonenc

16:10

@FenderLesPaul sorry... :(

FenderLesPaul

@gonenc haha it's cool I'm up to speed

gonenc

but I bet you knew it. it was all over the internet

Jimself

@JohnRennie with one obvious exception. All his answers are hard work

FenderLesPaul

I'm a GoT addict

John Rennie

Though the late lamented Ron could be, shall we say, unsympathetic at times.

0celo7

16:11

@all in chat session: why is it not possible to go from $\operatorname{Det}\Lambda=1$ to $-1$ via a cont. change of parameters

Shing

@Jimself then I will remove that from the answer. my main purpose for answering special relativity is mostly practicing what I am learning right now. I found it is quite a productive way to learn. (I am learning special relativity in my summer break)

gonenc

@FenderLesPaul to be dead or not to be dead. That is the question :D

Shing

special relativity type question

ACuriousMind

@0celo7 If the change would be continuous, the determinant would have to pass through 0.

FenderLesPaul

@gonenc idk about you but if I had to live in the GoT universe

I'd rather be dead :p

0celo7

16:12

@ACuriousMind and they always have to be invertible?

gonenc

@FenderLesPaul you could be a farmer who doesn't know shit about nothing

FenderLesPaul

@gonenc but what about the winter?

gonenc

@FenderLesPaul it aint coming wake up :D

it has been fucking 5 seasons since the winter started to come

0celo7

@ACuriousMind oh are linear trafos always invertible?

Jimself

@Shing the question is closed. Don't worry about it if it doesn't attract any more attention/votes

user54412

16:13

@Jimself Just one exception? I can think of several off the top of my head.

ACuriousMind

@0celo7 No, but the parameters describe only $\mathrm{GL}(n)$, don't they?

Jimself

@ChrisWhite True. I meant one obvious, persistent, and textbook exception

obe

@0celo7 There is a new weinberg QM lectures book coming out in december 2015.

Jimself

any technically proficient troll, really

ACuriousMind

(I mean, you didn't give me any indication of what parameters you're talking about, @0celo7 :D )

FenderLesPaul

16:15

@gonenc haha true

Shing

Carroll'a book is out of the store, and unbelievably costly on the amazon

0celo7

@ACuriousMind 3 boost and 3 rotation

Shing

any other recommandation for GR?

FenderLesPaul

@Shing he has lecture notes for free on the arxiv

gonenc

@Shing you can find it on www.google.com

FenderLesPaul

16:15

Carroll that is

0celo7

Hawking & Ellis only requires some algebra and calculus...allegedly

ACuriousMind

@0celo7 Those are all invertible, yes

FenderLesPaul

@0celo7 technically they do claim that

I've only seen one GR book ever

that literally starts from arithmetic and works up to GR

it actually defines what a negative number is

and eventually comes to the Schwarzschild metric

0celo7

@FenderLesPaul opposite of positive :D

gonenc

@FenderLesPaul that should be really boring to read

0celo7

16:17

or: numbers left of positive

FenderLesPaul

amazon.com/…

obe

@0celo7 I concur, basic algebra and calculus.

gonenc

though it is incredible that he can do that

user54412

@Shing Sorry, wrong link earlier. Try this one

0celo7

@gonenc just make a 20-volume series going from finger counting to categorical QFT

gonenc

16:18

@FenderLesPaul I think on the other hand that anyone who haven't heard of negative numbers will be able to understand that

0celo7

@ACuriousMind ok but why

FenderLesPaul

@gonenc yeah idk why someone who doesn't know what a negative is would be interested in learning GR...

gonenc

@0celo7 we should start teaching reading too before we get to finger counting :D :P

Shing

thanks all, but I always feel something is missing for those draft.

0celo7

@ACuriousMind because the inverse is obtained by multiplying by the Minkowski metric?

ACuriousMind

16:19

@0celo7 ...uh, you can just always rotate back or boost in the opposite direction?

0celo7

@ACuriousMind too intuitive

I want an answer using words I have to look up

Shing

Is Carroll's book the best for beginner in GR? I am thinking getting exploring black hole GR by Talyor and Wheeler. Anyone has read it?

ACuriousMind

@0celo7 Best I can do is: Because Lie groups are groups, and all group elements are invertible

John Rennie

@Shing Yes, and it's a great book for the interested amateur.

0celo7

@ACuriousMind I understand all of that

ACuriousMind

16:22

@0celo7 Good :)

John Rennie

@Shing But I don't think it's a great introduction for someone who really wants to learn GR

FenderLesPaul

@Shing Taylor and Wheeler is great

Shing

@JohnRennie Why?

FenderLesPaul

don't hesitate buying it

John Rennie

Exploring Black Holes is one of a very select band of books that are best described as books for the non-non-nerd.

0celo7

16:23

non-non-nerd?

user54412

is that a double negative prefix?

John Rennie

That is, you need to work at the maths to understand it, but anyone with a science degree should know enough maths for it to be accessible.

Jimself

wanna talk about great books? I have an original printing copy of the following book sitting at home. Brilliantly written

The Evolution of Physics

The Evolution of Physics: The Growth of Ideas From Early Concepts to Relativity and Quanta is a science book for the lay reader, by Albert Einstein and Leopold Infeld, tracing the development of ideas in physics. It was originally published in 1938 by Cambridge University Press. It was a popular success, and was featured in a Time magazine cover story. == Background of collaboration == Einstein agreed to write the book partly as a way to help Infeld financially. Infeld collaborated briefly in Cambridge with Max Born, before moving to Princeton, where he worked with Einstein at the Institute for...

David Z

yay? I made it

user54412

A mod! Quick, everyone hide.

4

0celo7

16:24

already hiding

user54412

::whistles::

Jimself

::Jim becomes Jimvisible::

3

FenderLesPaul

@Jimself evolution of physics is a lie!

John Rennie

@Jimself which is better than trying to be seductive

ACuriousMind

::looks frantically around, then just plays dead::

Jimself

16:25

@JohnRennie ::seductively Jimvisible::

John Rennie

Does anyone remember a book called The New Physics?

David Z

@Jimself too bad this isn't IRC :-P

0celo7

boring chat session

John Rennie

Well I think it was called The New Physics, but a quick look on Amazon hasn't located it.

0celo7

...is that Justin Bieber's avatar?

user54412

16:27

@Jimself I'm actually kind of interested to read that now. A pre-Kuhnian history/philosophy of science book.

ACuriousMind

@JohnRennie What was it about, roughly?

John Rennie

Published in the 80s and giving a non-non-nerd guide to the current frontiers of physics.

Jimself

@ChrisWhite written by Einstein

FenderLesPaul

@ChrisWhite what is Kuhnian?

Jimself

the writing style and content has an elegant grace. You can really tell how brilliant he was

David Z

16:28

@0celo7 yeah, seems that way. But at least people are here.

John Rennie

@ACuriousMind It might be this one:

amazon.co.uk/The-New-Physics-Paul-Davies-x/dp/0521304202

Jimself

my copy was printed in 1938. I found it at a random book sale at university and bought it for $5

user54412

@FenderLesPaul Kuhn wrote en.wikipedia.org/wiki/The_Structure_of_Scientific_Revolutions -- very influential (perhaps too influential) in the field.

ACuriousMind

@FenderLesPaul The dude with the paradigm shifts

John Rennie

Though the cover looks different to what I remember, and I thought it was by multiple authors. The timing (1984) is right though.

Shing

16:29

I got the New physics for free from my professor :P

user54412

the idea is that science progresses by bits and pieces, and then once enough evidence mounts that something deep is very wrong, everything is reconstructed in a new paradigm

ACuriousMind

I wasn't even alive in 1984, no way I could "remember" that :D

user54412

he was probably very influenced by relativity and QM the generation prior

John Rennie

@ACuriousMind Thanks for that :-)

0celo7

@ACuriousMind I'm gonna fix that...

Jimself

16:31

@ChrisWhite amazingly, he advocates in the book that we should stick to fields instead of treating everything like quantum particles and says that we should try to approach everything like it is all fields and that particles are just regions where the fields are particularly strong

talk about hitting the nail on the head

ACuriousMind

@JohnRennie No problemo ;)

John Rennie

Does anyone know of a book comparable to Schutz's General Relativity but about quantum field theory?

FenderLesPaul

@ChrisWhite @ACuriousMind cool thanks!

looks very interesting

ACuriousMind

@0celo7 Oh, I missed one of the positions? Yeah, go ahead

What's very annoying is that the indices in ${{\omega_\mu}^a}_b$ don't have all the same baseline, though

The $b$ should align with the $\mu$, imo

John Rennie

I've looked at various introductory QFT books, but they're all targetted at students who can put in some quality time to studying them. For those of us with a day job it would be nice to have a book you could dip into.

ACuriousMind

16:34

But I don't think the package needed for such indices is enabled in MathJax, is it?

0celo7

@ACuriousMind agreed

user54412

@JohnRennie amazon.com/Quantum-Theory-Nutshell-Edition-nutshell/dp/… perhaps? (probably more advanced than Schutz, but it's the best I can do)

0celo7

@ChrisWhite no

that book is just...confusing

user54412

@0celo7 Confusing for a first book, or confusing for a person who already knows the advanced, "right" ways to do things?

0celo7

@ChrisWhite both

John Rennie

16:36

@ChrisWhite I have a (PDF) copy of Zee, but I find it hard compared to the way Schutz writes. With Schutz I found I could do a chapter at a time and work my way steadily through it.

I've so far failed to do that with Zee's book.

FenderLesPaul

@JohnRennie amazon.com/Quantum-Field-Theory-Gifted-Amateur/dp/019969933X

John Rennie

@FenderLesPaul I have that book too, and I find it hard as well.

Maybe QFT is just harder than GR

user54412

In undergrad QM, our prof switched to a small, old monograph on many-particle QM to transition into QFT. I can't remember the name of it though.

ACuriousMind

@DavidZ: Are you back in China again? How was the mountain climbing?

FenderLesPaul

@JohnRennie I don't think I know of an easier book that still does the subject justice

I would agree

QFT is definitely way harder than GR

Shing

16:38

Is Zee's GR good for a beginner? It is pretty relatively cheap in my university's book shop. (somewhere $25 usd)

David Z

@ACuriousMind mountain climbing was fun... 900 steps :-P I got a few good pictures.

0celo7

@Shing Yes

David Z

But I'm at my family's home in NY now. I don't get back to China until next month.

FenderLesPaul

Yay NY!

David Z

:-)

Kind of in the middle of a grand tour of the US

John Rennie

16:40

I wish long term members of this site would stop bashing out answers without first checking for obvious duplicates!

Shing

@DavidZ You work in China? I have heard of China plans to build a hugest accelerator, did they start building it?

FenderLesPaul

@DavidZ go to Venice beach in SoCal

you will not be disappointed

possibly scared

user54412

I've heard about this press release from a number of different sources now, including this question. It's based on this paper from today's arxiv. The summary: confirmation that yes, indeed, the universe is measurably diminishing in energy output.

2

ACuriousMind

@JohnRennie I definitely agree, but searching for duplicates is more boring than writing an answer ;)

0celo7

does anyone know a good djvu to pdf converter?

John Rennie

16:44

@0celo7 Any DJVU reader then print to PDF?

ACuriousMind

^that

0celo7

@JohnRennie I want it to spit out a good quality PDF

John Rennie

@0celo7 print to PDF should give you as good quality as anything else

0celo7

@JohnRennie you have something in mind?

ACuriousMind

@0celo7 If you don't choose down-scaling printer settings, why would it diminish the quality?

John Rennie

16:45

Or were you thinking about extracting the individual images then re-assembling them into a PDF?

1

Q: What does it mean to observe?

This is a layman's question. The only thing I know about quantum physics is from casual reading and documentaries. I can imagine electrons being probabilistic waves. Their position is an infinite number of weighted points and only upon observing the actual position do we know which of those point...

quantum-mechanics measurement-problem observables

0celo7

I've been using an online app where you just upload the DJVU and 5 minutes later you download the PDF

John Rennie

Though actually I think duplicates aren't necessarily a bad thing.

@0celo7 Oops, sorry, slip of the mouse.

I use DjView by DjVuLibre

ACuriousMind

IrfanView can also view DJVUs with a plugin

John Rennie

Though I have so say I really don't like DJVU format because you can't text search it.

user54412

::finally looks up what djvu is::

0celo7

16:48

yes but when you're given a DJVU...

David Z

@Shing not yet, it's still being planned... actually they may have multiple competing plans in the works, from what I've heard

user54412

wait, why does this file format exist?

David Z

@FenderLesPaul I only have like a day in LA but we'll see

ACuriousMind

@ChrisWhite good question

John Rennie

@0celo7 This would be an entirely legal copy of course, and not something that drifted in on a BitTorrent stream :-)

FenderLesPaul

16:50

@ChrisWhite I think it's supposed to be a highly compressed version of PDFs

makes it easier to distribute I guess?

0celo7

@JohnRennie of course, and I have the physical book

just too lazy to go to the other room to get it :)

John Rennie

@ChrisWhite There are old books that will never be republished as a PDF. DJVU is a reasonable way to turn them into an electronically accessible form.

No-one in their right mind would choose it for a new book

ACuriousMind

I think Chris is asking why we don't just produce the scan as a PDF

0celo7

oh lord this quality

user54412

hasn't OCR gotten to the point where, you know, it works?

John Rennie

16:52

@ChrisWhite Basically, no. And anyway what about all the diagrams?

user54412

@ACuriousMind that too -- are megabyte-sized files just too big for people?

David Z

Well, not everyone has a fast internet connection available

A megabyte can still take like 20 seconds to download

:-P

John Rennie

@DavidZ You never used a 2400 baud modem then? :-)

0celo7

I get mad when Steam downloads go below 10Mbps...

millennials are spoiled

FenderLesPaul

@0celo7 you're not a millenial

liaaar

0celo7

16:55

close enough

David Z

@JohnRennie ...? I'm talking about these days

ACuriousMind

@ChrisWhite Random test gives me 9MB DJVU file against 40MB PDf file...well, that's not a neglegible difference, I guess

John Rennie

@ACuriousMind Yes, I'd say DJVUs are typically 20% to 25% the size of the same (scanned) PDF.

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