8:04 PM
Am I wrong, and are questions like physics.stackexchange.com/questions/206307/… totally acceptable on this site?

0

In Wikipedia, spacetime intervals are presented explicitly under the heading "Spacetime intervals in flat space"; apparently including a presentation of spacetime intervals for (all) pairs of events in flat spacetime. Now, certainly spacetimes may be considered such that none of their subsets c...

Huh?

@0celo7 Did you even read the question? :P
@0celo7 Ah, there ya go

@Danu Then I read the body
Interesting solution btw

Another "revival" :D

Do you have a physical reason for the time is finite?

8:11 PM
Also most books don't bring up the definition of de Sitter in terms of the coordinates on a hyperbola in 5-space.

@Danu I thought that was the definition.

@0celo7 The physical reason is that one can go to any point on the manifold in finite time

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I hope that shatners bassoon in relative to an individuals quota on comedic flatuations is not overlooked

@0celo7 One can just define it as a solution to the EFE's. I agree that the embedded one is nicer (I also started my thesis with it). It immediately shows what the isometries are.

@Danu I'm looking at Fig. 16 (p. 125) in Hawking-Ellis
I'm trying to locate the path of your observer.

8:19 PM
@0celo7 Good luck :P

@Danu Do you know what it looks like?

@0celo7 Just solve for the trajectory (take some simple initial values) from the equation of motion.

Isn't that what OP tried to do?

@0celo7 I didn't read the full post, haha. I had just done that calculation before so I knew I could solve it
My solution comes from Mukhanov's (excellent) book.
I strongly recommend it, especially to you.
Hi @Maruska

"especially to you"
now what does that mean >>

8:27 PM
@0celo7 It's better than any other book I know in giving you the right intuition.
This is something that you would profit from, IMO.

he has two books

I mean the QFT in curved spacetime one
It also gives a nice, unified view of physics from classical mechanics to QFT in curved spacetime; everything is essentially the same!

why is cambridge univ. press such a rip off
>$100 Just read the online version---it's legally available anyways The draft of the book, that is. But it's almost identical I know but I was checking Amazon out of curiosity 8:30 PM @0celo7 That is, indeed, a ridiculous rip-off. It's a quite short, small book. @Danu Their pricing is very inconsistent the anniversary edition of GSW is$100
that's >1000 pages of material
and somehow this <300 page book is more expensive
you should ask him how big of a cut he gets

Hah, probably not much.
But he's comfortable, don't worry ;D
Also I think I'm gonna buy Lee's book :D
MyCopy is the best
Now I'm also considering buying Lüst's ST book

like I warned Bajoran, it's very dry
also very CFT heavy

That's fine, I'm also taking CFT at the same time
Both Lüst and Blumenhagen are my prof's for [the courses on] their respective books
I'm pretty psyched

::does projectile motion problems::
screw you

8:36 PM
@0celo7 story of my life

I don't get to do anything remotely interesting until my third year

@0celo7 That's up to you innit?

next year is analysis and algebra, ugh
@Danu what do you mean?
I can't skip required classes
I do need to get a degree after all

Or not attending the lectures when they're too easy for you. Have you even talked to your program coordinator yet?

@Danu I've talked to him many times.
"you need to strengthen the basics"

8:41 PM
@0celo7 That may be good advice, then.
(It's also roughly the advice I used to give you :P)

I think Dr. Lang is the only one who hasn't treated me like an imbecile
@Danu I'm doing projectile motion
I don't think you can understand how mad I am that I'm paying to do this

I guess you should do something different in the way you talk to the program coordinator, then.
Do you have any serious "evidence" that you're not just a regular-ol' high school student?

Nope

Maybe that's something you should work on then.

How?

8:45 PM
Make some evidence on your first midterms.

@0celo7 Have people vouch for you, do some extracurricular projects, etc
@Rigor Probably not that impressive for a student to do well on the first exams. But yeah, of course you should get good grades for people to believe in you.

@Danu vouch? and I've "joined" a research group

@0celo7 What is the research on?
@0celo7 "vouch for someone" y'know

@Danu not exactly sure
I went to the meeting on tuesday
I need to go to Lang's office and figure out what exactly I need to read up on

He does experimental stuff though, right?

8:47 PM
sounded like a lot of solid state physics, crystal structure, X-ray scattering
mhm, the theoretical guys told me to come back when I know something

@0celo7 Really? :P What'd they say exactly

@Danu one of them had never even spoken to an undergrad before
apparently I need to read Jackson
oh, damn
I was supposed to send him an email about the undergrad courses I'm planning on taking

@0celo7 Not forgetting the things you promise is the first step towards being taken seriously :P

@Danu yeah well Freire has been looking for references on twistors for 3 weeks now

@0celo7 Who's Freire?

8:54 PM
@Danu my differential equations professor
he researches geometry and PDEs

::sigh:: Do people actually think "I don't understand this and it involves light in any way at all. Obviously it's a physics question." or does it just seem that way?

@dmckee sorry, what?

A pet peeve of mine. Look on the site.

@dmckee re this or something else?

0

I know that our brain perceives two images from two eyes and combine them to see 3 dimensions and the 3D stuff uses this. But how this works and how can there be two images ? Thanks in advance, good night. (If I did something wrong, sorry. I'm not native speaker.)

9:00 PM
oh

FITS is a pretty generic format, so the trouble comes in know how a particular subfield is using it. Those question aren't very physicy either but at least they are questions that physicists actually have.

@Danu Yes, definitely interested.

@0celo7 it might be hard to get theory research in the first semester or year
should be much easier second year

@FenderLesPaul the guy who does theoretical fusion has no one less than a PhD candidate on his team

yeah and?

9:07 PM
well I need to get back to him
he's never talked to an undergrad who was interested in his work

Where I'm from, research as an undergraduate is not really a thing, at all :P But that may be a Dutch/European thing.

well you're also theoretical
I'm not
who wants to see this impressive amount of mucus I just spat out

@0celo7 well I can't say anything then

my throat feels a lot better now

@Danu I think it is a European thing yeah
system seems to be quite a bit different in the US as far as grad school admissions go
most of the emphasis is on one's undergraduate research

9:11 PM
for engineering your internships play a big part

but it usually tends to be experimental

also how personable you are

yeah

grad schools want to get people who have large earning potential
and weird people who can't converse won't get the top of the line jobs

yeah

9:15 PM
Says who?

it's nice to get to the stage where you don't have to have heart attacks taking classes because the tests determine the entire grade and stuff though
but then again in the US physics classes are pretty inflated grade-wise
with possible exceptions
@ChrisWhite were physics classes at CalTech inflated?

@Rigor my brother used to do the hirings for his department in his company
he's an electrical engineer
his number 1 piece of advice to me was go to football games because recruiters will ask if you went to football games

:D

they don't want to hire people for the top positions if they don't work well with others
also there's the halo effect

user54412
@FenderLesPaul They were somewhat inflated. I'd say a better word would be de-spread. Very few people got less than a B, and about 1 person per year would manage to get an A+.

user54412
9:20 PM
That said, the physics department had the right attitude about grad classes -- they were all pass/fail, even if you were an undergrad.

@ChrisWhite That must've been so nice. The pressure is pretty high here, at least to me.

@ChrisWhite nice
and yeah that's a good philosophy to enforce
grades in a QFT class at caltech holy shit I'd cry

my dad's grad school experience as he tells it: study like a mofo all week to get an A, get sloppy drunk on the weekend

over here they force you to take QFT1 for a grade if you're an undergrad
but if you're a grad student you can take it pass/fail
what the hell kind of logic is that?

@0celo7 Sloppy drunk doesn't have to interfere with the studying

user54412
9:25 PM
Our core applied math (complex analysis/differential equations) class was taken by a large fraction of undergrads and grads, the former for grades, the latter not. What's really sad is that it's a sophomore level class, and many of the incoming grad students had to take it because their undergrads never taught them how to do contour integrals.

@Danu I know, but grades were very important

@0celo7 I don't mean it that way

that's the moral of the story
@ChrisWhite I don't have contour integrals in my schedule
I could replace topology with complex analysis

caltech has a 3 semester GR sequence

although I might take the analysis complex analysis class

9:26 PM
mmmmm
looks fun

@ChrisWhite Hmm interesting. Contour integration is definitely part of the undergraduate curriculum in Amsterdam.

god I hope I get into CalTech
sells soul to devil

@0celo7 oooh cool. The only one they have for undergrad here at ucsd uses this book amazon.com/Complex-Variables-Applications-James-Brown/dp/…

@FenderLesPaul I applied and got rejected!

@Danu damn that doesn't bode well for me

9:28 PM
this is for the PhD btw, idk what about you

yeah PhD program

user54412
@FenderLesPaul You have to sell your soul to Feynman.

if I get a complimentary set of bongo drums I'm down

I think being European is a disadvantage too. Maybe you'll stand a better chance :)

@NeuroFuzzy yeah there's an undergrad class called "complex variables" and a grad class called "complex analysis"

user54412
9:29 PM
My profs joked that they get paid extra every time they mention Feynman's name. After a while I started to believe they might not be joking.
2

@Danu I got wait-listed way back in '89. Then I accepted at UCSB.

> MATH 443 - Complex Variables

3 Credit Hours
Introduction to the theory of functions of a complex variable, including residue theory and contour integrals.

Caltech is like one of the few choices I have for pure GR theory research
I'll clean all of their bathrooms for life if I have to

@0celo7 Seems legit

9:31 PM
> MATH 546 - Complex Analysis

3 Credit Hours
Holomorphic functions, Cauchyâ€™s theorem, Maximum Modulus theorem, Schwarzâ€™s lemma, normal families, Riemann mapping theorem.
(DE) Prerequisite(s): 545.

@NeuroFuzzy you go to ucsd?

@FenderLesPaul Princeton?

@0celo7 Very nice. Hope you take that! :D

@Danu Probably my fourth year.

@0celo7 @ChrisWhite probably knows inside and out whether or not they have pure GR theory people but I think all their research is numerical GR/astrophysics or quantum gravity stuff

9:33 PM
@ChrisWhite why is Feynman put that high on a pedestal?

There truly is not enough time to take all of these classes.

@Rigor He was both intuitive and mathematically strong.
And an infectious personality by all reports.
Especially his own.

he definitely had a face that was easy on the eyes
dat smile

Gell-Mann didn't like him.

MATH 547 - Applied Linear Analysis

3 Credit Hours
Banach and Hilbert spaces, linear operators and spectral theory, Sobolev spaces, applications.
(DE) Prerequisite(s): 545.

user54412
9:34 PM
@FenderLesPaul That's my understanding too. But that's my perspective as someone tangentially related to numerical GR, and as someone not in the physics department proper. There might be pencil-and-paper GR types hiding that I don't interact with.

@dmckee I've read several accounts of him being a bit of a pompous pr*ck quite often.

never noticed that one before

@Rigor Gell-Mann very nearly doesn't like anyone.
@Danu Yeah, and he seems to leave everyone with either a very good or very bad impression. Never met him myself, but I have shaken Gell-Mann's hand once.

@dmckee Hmm

user54412
@FenderLesPaul and the voice -- that old school NY accent

9:36 PM
oh, throwing out names are we?

@ChrisWhite god I love that accent

Sen. Warren said my omelette smelled good

He's not the only one like that either. Leon Lederman generates similar reports.

@ChrisWhite plus he grew up in Long Island

I've met him, and he had clearly turned the charm on for the evening.

9:36 PM
so I gotta like him for that

But reports of what he's like when he turned the dial the other way are scary.

did Feynman know that electron = 511keV photon in a Dirac belt configuration?

@0celo7 Politicians...

user54412
@0celo7 still trying to figure out if that's a euphemism

9:38 PM
@ChrisWhite no, she really liked my eggwhite omelette :D

was it true that Schrodinger was a player?

totally
I want to bear his children

@FenderLesPaul He worked out his eponymous equation during a mini-break with his mistress (leaving the wife at home), does that count?

how does that happen

Do you know if Feynman's Princeton grad school entrance exam math score record been broken yet @ChrisWhite?

9:42 PM
@FenderLesPaul A pedophile.

forreal?

user54412
@Rigor no idea, but probably? if such exams even exist anymore

@0celo7 He tried to start a relationship with a 16-year old when he was around 40

user54412
did I mention I'm in astronomy, where we don't that whole "written exams in grad school" thing physics does ;)

@Danu re fermi problems: our fermi problem group project had results ranging from 0 to 10,000

9:44 PM
And an even younger girl when he was around 30, IIRC
@ChrisWhite screw you :P

pedo is prepubescent, 16 is certainly not prepubescent

user54412
@Danu And I thought Europeans were supposed to be more liberal-minded about things :P

perhaps you mean hebephile

@ChrisWhite Oh, don't you worry, I personally know more extreme cases.
@0celo7 I didn't realize. Sorry :P

@Danu most people don't, but it makes a difference
being attracted to a 10 year old is a lot different than a 16 year old...thus there are different words
after all, there is a biological basis to hebephilia, i.e. "get em while they're young"

user54412
9:48 PM
@0celo7 A distinction lost on those of us much older than you.

@ChrisWhite it's in the AP psychology curriculum

I read once he got the highest in math and the lowest in english @ChrisWhite

@ChrisWhite Hahahahaha

@ChrisWhite what you're saying does not make sense
puberty is puberty

9:51 PM
It's not lost (yet?!) on me ;)
@Rigor what a word

@dmckee damnn
@Danu daaaaamnnn
sometimes it's hard for me to grasp the fact that super brilliant famous physicists don't just do physics all day
and that they're human

In the last couple of decades society has ceased to make a carefully drawn distinction between people who seek out sexual relationships with young but sexually mature people and those who seek them with pre-pubecent people.

Says who

Uh the chat doesn't work on my laptop anymore

@dmckee I agree that the difference is important.

9:54 PM
that was weird

In Schrödinger's time the distinction was treated as important by more people.

Meanwhile, someone accuses me of "throwing a tantrum" and then proceeds to get quite angry with me.
@Danu Proofs about Clifford algebra isn't physics either. That's mathematics. Off topic. physics.stackexchange.com/questions/89611/…ShanZhengYang 1 min ago
@dmckee I blame this on you!!!

His fondness for teen girls would have been considered inappropriate but not the moral stain it would be look upon today.

user54412
And in Plato's time there was no distinction again, but in a reversed kind of way.

But I get the feeling it was looked down upon by many in polite society.

9:55 PM
@Danu It irks me that some questions that are off topic don't get a single close vote.

I guess that question of mine should be closed by today's standards

vtc

however, #yoloswag

@Danu does it show you a VTC if it gets retracted

Speaking of perversions anyone find out what that mit physics professor did?

9:58 PM
@0celo7 Not anymore, no.
@Rigor Inappropriate things with students.
One of my friends actually knows one of the (almost-)victims.

@Danu Tenure is no protection at all when that comes up.

Young ones?