This might be the wrong place for this, but does anyone have any experience with turbomolecular pump bearing oil?

@ACuriousMind Thanks a lot for the feedback on the essay!

@dmckee Do you want in? :p

Test

@BernardoMeurer is my image messed up?

@0celo7 Yes it is

huh it looks fine on my laptop

It's a bizarre image

Like a fucked up manifold

It is Hausdorff though, unlike myself

:/

I do, yes

@BernardoMeurer how do I fix it?

test 1

test 2

when my image gets bigger I can see it

It takes a while for it to propagate

just be flipping patient

look

it works sometimes

In hindsight, was the quadratic formula ever useful to learn?

It seems worse than completing the square in every way

I use it all the time

@SirCumference tbh back in the day I was so fast at using the formula that I doubt completing the square would be faster

And nowadays when I'm in an exam I also always use it unless the square is obvious

Which usually isn't the case

@BernardoMeurer You can't reduce $x^2+2x+3$ with the quadratic formula alone

Sure, but that has complex roots, I don't care for it most of the time

And when I do I get to use a calculator

I don't remember the quadratic formula

@BernardoMeurer Well when you're asked to do partial fraction decomp, how are you going to do that?

@SirCumference when would one ever have to do that

@0celo7 I got screwed over royally in calc II for not remembering how to complete the square

Well, "screwed over royally" is a bit of an exaggeration for "lost too many points for a dumb reason on homeworks"

The key is to not take calc 2

@SirCumference Whenever they make me do partial fractions I give up and leave

So far it has worked

@0celo7 Well, I wish past me had that option...

My brother has the right answer

The only usefulness of the quadratic formula is that the discriminant lets you save a few seconds to see if a quadratic is reducible

God I'm tired...

@SirCumference You're being a grump

@BernardoMeurer Perhaps...

@BernardoMeurer you know that awful book i showed you?

I want to read it

It just seems like, in hindsight, high school gave its students a lot of pointless information

I'm reading a summary of the main arguments and it's basically stuff I love

@SirCumference Don't go down this path, it leads to nothing but frustration

@BernardoMeurer "This path"?

@SirCumference This path

@0celo7 Don't do it

WHY NOT

it is not a path you can return from

It's like installing NetBSD as your main OS

It changes a man forever, in dark, dark ways

@JohnRennie Did you get my Teriyaki messages?

@JohnRennie @Slereah What rotationally invariant vacuum solutions besides Schwarzschild are there?

You need staticity to nail it down, right?

All spherically symmetric vacuum solutions are Schwarzschild (and static)

It's the Birkhoff theorem

oh, you don't even need to assume static?

No

yeah I knew that

thanks

The only other way to get a vacuum spacetime is to add gravitational waves, but those can't occur in a spherically symmetric vacuum spacetime

You can't get quadrupolar moment

@0celo7 I did. Sorry for the slow response but I have a server down

@JohnRennie next weekend I will slow cook pork

You hear that piggies? You gotta run FAST next weekend! :-)

@JohnRennie doesn't look too great in the picture, but boy does it taste amazing i.gyazo.com/59d97467bb4d67cd1145f3533bc20b88.jpg

I used the spoon to shred the chicken it was so soft

Pork isn't my favourite meat. I like bacon (who doesn't?!) and in pies and sausages, but to me pulled pork only tastes of whatever sauce you used on it.

I am currently making chicken and baked potatoes

On Sunday I bought a load of chorizo sausage that was on offer, so next weekend I'll be making something with chorizo. I haven't decided what to make yet.

@Slereah for breakfast? :-)

Well I woke up at 5 AM

And I didn't have dinner yesterday

So I am mighty hungry

@JohnRennie ok I'll use some of my tenderloin to make Schnitzel again (I still have 5 pounds of pork in the freezer) and then...not sure what I'll slow cook. Maybe I'll make a baked feta instead

plus it's potatoes

So it's gonna be 1h30 to bake already

Although getting that much cheese and vegetables will be expensive

But baked feta is probably the single greatest food

Probably monstrously unhealthy. Definitely too expensive

Do you know what I'm talking about @JohnRennie?

Feta is healthy ...

Unless you deep fry it in lard :-)

Ok then. I'll choose to believe you

I can just use half as much feta as I would on my parents' dime and use more carrots and stuff

Bell peppers are expensive

@JohnRennie What is a good way to use garlic in food so that it gives its smell/taste better to the food?

Yesterday I used Paulie's method and it was quite better than my previous tries

@lılostafa I'm not sure it makes a lot of difference how you slice it. I usually use a garlic press. The thing with garlic is that it gets increasingly milder as you cook it. If you want a really strong garlic flavour add the garlic right at the end of the cooking.

Still cooking

Plz hurry potatoes

I am hungry

@0celo7 there are all the Schwarzschild variants of course - Narai, Schwarzschild de Sitter etc. I don't know of any others.

none of those are vacuum solutions

the only other spacetimes like that are just topological variants of Schwarzschild

"the wave of death is a gravitational plane wave exhibiting a strong nonscalar null curvature singularity, which propagates through an initially flat spacetime, progressively destroying the universe,"

Not the universe D:

That is where I live

Apparently the original paper about wave of death is a penrose paper that isn't available online >:|

I'll have to order it

@JohnRennie The way you mince Garlic does matter, but only if you're not cooking it for a long time.

Ah, I see you've now qualified your initial statement :-)

I use a garlic press and I've never noticed any great difference between pressed and chopped garlic. But then I tend to use it in risottos, pasta sauces etc where the garlic is cooked for a while.

@ACuriousMind Interesting... I don't like using a garlic press and most often mince mine with a knife, although have used pestle and mortar before

I like to make peppers fried in some olive oil with garlic and salt as a snack/appetizer, it's very noticable there since I only add the garlic at the end as to not burn it.

@ACuriousMind Yeah, I've been 'served' [read: they made it at the table] pestle+mortared pesto that had garlic in it before

@Mithrandir24601 why don't you like using a garlic press? I ask just out of curiousity. It seems to me a very convenient way to prepare garlic.

@JohnRennie I always find it really hard to get all the garlic out, so find I need to use more garlic to end up with the same amount, then it's a nuisance to clean. I also just enjoy mincing it with the knife :)

@Blue *Schwartz :P

3 hours until the neutron star merge announcement

our department has a pizza watch party

^ This has everything to do with the message by Amin.

Boo!

@Blue that's old school. Is he trolling you?

Yeah but if you can just pick that up and read it you're the smartest person in here

Why doesn't he recommend some actual beginner analysis

@Blue yeah. It's a reference book

It's functional analysis. Why wouldn't you need analysis?

@Blue I know the book well. Strange autocorrect.

Why exactly do you want to read a book on functional analysis? (If you hope it gives you some insight into quantum mechanics as practiced by the majority of physicists - it really won't. If you have another reason, go ahead.)

@Blue A good math background doesn't hurt, but I wouldn't say functional analysis is necessary unless you want to do the kind of mathematical physics that concerns itself with the functional analytic issues. For the broad areas of theoretical physics you mention, I'd place higher importance on differential (and eventually algebraic, in the case of string theory) geometry and representation theory of Lie groups (what physicists tend to call "group theory")

Functional analysis is now basic?

@Blue I think I'm getting the set for my birthday.

@Blue Physicists who worry about functional analysis are mathematicians. Physicists who worry about algebraic geometry and representation theory can still be physicists. Strange, but that's how it is.

@Blue Reed and Simon talk about the Lebesgue integral but I found it completely unreadable. I haven't looked at it since I learned measure theory, but I suggest you learn measure theory first.

Also they might require you to know complex analysis. For what they do to really make sense, you need to know the analysis part.

@0celo7 What have you done to your face? :P

@0celo7 Ah, yes, @Blue, the basics of complex analysis are also definitely very helpful in many areas of theoretical physics.

@ACuriousMind I'm a minimal surface.

@Slereah What happened to your legal farm

@0celo7 Aha.

@Blue That is far different from Reed and Simon

I don't think there's any instance where functional analysis will make you understand physics better. It's quite the opposite, in fact.

Sounds... unhelpful

@0celo7 In that case, why read it?

@Sid Physics is not the ultimate goal of everyone :P

@Sid Because I'm interested in mathematical aspects of quantum mechanics. I knew the physics before I learned the math. I think this is a great approach. Bra-ket notation is a powerful tool if you want to know what is probably true in nice scenarios.

@SirCumference what

@Slereah I think @SirCumference is a bit behind the times as usual and is asking what happened to your Mr Crabs picture :P

It's a barn, not a farm

FINALLY! There is CONTENT!

@ACuriousMind indiana.edu/~minimal/archive/HigherGenus/Higher/…

Cor hurricane Ophelia is now arriving on the UK coastline. Somewhat diminished in strength, but it's still pretty windy out there today!

@ACuriousMind I figured I should have an avatar relevant to what I do

@0celo7 Ah, like I do :)

@ACuriousMind Sit around and play video games?

::Infinity Bomb at h bar now set to indefinite Standby. Now evaluating status of Infinity Bomb at maths chat::

:P

@0celo7 Precisely

@JohnRennie Be careful.

Don't get lost and don't die either. :P

@Sid it's no longer really a hurricance, though sadly there has been a fatality.

@Slereah Aren't barns on farms?

Well what happened to the pic?

It wasn't professional

@0celo7 Lawyers have professional degrees tho

@Slereah Is not a lawyer

@ACuriousMind that site is a great place for whacky avatars

But he had a lawyer on his pic

the hell is that manifold

What on earth is that double wormhole

Hello

and that's not a wormhole, but some weird trumpet like protrusions on a hyperbolic surface

@ACuriousMind does my avatar look like a CY-fold

@0celo7 Only insofar as I think most other user avatares of manifolds on physics.SE are CY folds

Gosh, the hurricane has just blown my butt over

@JohnRennie is that a euphemism?

Why does @ACuriousMind have John Rennie's pic?

@SirCumference What?

@ACuriousMind who actually is the person in your image?

@0celo7 :-) It's the water butt that collects water from rainfall for the garden. Courtesy of the storm it is now rolling around my garden.

Elsa from Frozen

@Semiclassical

it does have the right look

@JohnRennie rofl

@ACuriousMind Your pic shows JR for me

Reloaded, same thing

...huh

lœl

@SirCumference That's copyright theft! I demand royalties!

i'm seeing different pics, so i dunno

should've called it identity theft

@SirCumference lol

Has ACM really been JR all along?

let's all change our avatars to be JR's

It would certainly freak out newcomers to the room ...

"JR is the 99%" would be the new room slogan

Anyway I'd better go out and pick up my butt before it does any damage.

@JohnRennie you need to go on a diet

...context

also what is with the Brits and strange names for things?

something I was thinking about

on the one hand, the whole 'workshop' thing has consistently been pretty silly

@0celo7 That's because the Brits are strange. :P

largely, i think, because the organizer has been more interested in their 'right' to have a workshop than any compelling interest in it

on the other hand, the idea of informal 'interest groups' for non-standard topics doesn't strike me as a bad one

so, the question: How would one organize that in a useful way?

(the answer may well be "one can't" because it's hard to develop a critical mass of interest on SE)

@Sid I left at 8.30 this morning expecting the weather to be awful. What I got was a lovely warm temperature (it felt tropical) and a pretty red sky with a stiff breeze... If that was a hurricane, well... it's the best weather we've had in a fair few weeks

@Mithrandir24601 Are you sure you're still not exactly in its eye? :P

@Semiclassical I think the useful way of organizing this might be the other way around: First get the critical mass of people interested in some topic, and then get them to decide together how they want to do something about that shared interest

yeah. bottom-up, rather than top-down

@lılostafa yeah, pretty sure - it was like that all morning and it's turned into a nice warm day :) although we only got a small bit of it here - the eye is a couple of hundred miles away

i also think 'interest group' is a more useful framing than 'workshop'

a workshop is about bringing together experts to talk about a topic. that's not realistic in this setting

I'm borrowing that phrase from personal experience, btw: There's a pretty good philosophy and history of science department on campus, and there's a "Physics Interest Group" which meets for about 2 hours every other Friday

@ACuriousMind you never answered my question

not a lot of physicists show up to that, mind :P

@Semiclassical Yes, definitely.

@0celo7 Which one?

@ACuriousMind Does QOGS have non-QFT purpose?

The problem, of course, is to find some topic which people would be interested in

But that's the right problem to have. If people are interested in something, then they'll talk about it, and if enough people talk about it then that's by definition an interest group.

@0celo7 I imagine this was mentioned earlier, but: QOGS?

@Semiclassical Quantization of gauge systems, a book by Hennaux and Teitelboim

ahh

@0celo7 Sure, large parts of it are kept in the regime of finitely many degrees of freedom anyway

I'm not sure how often you'll actually stumble over a constrained system you want to quantize, though

I had a chat room in maths that accidentally function like an interest group chat room. Basically, instead of first acquiring a critical mass of people and then decide what topic to do, I use that chat room as my rough work sheet, and then suddenly the current topic (foundations of mathematics) attracted so much interest that people started joining automatically, thus the critical mass kinda catalyse its own formation itself

Yeah.

I may try that approach myself.

One reason I seemed to write a lot of messages that directs to no one is because if they are interested, they will ask. But over the years from both Ted's advice and also me trying to clean up my mailbox, even when a group is interesting, when it started to flood, it gets hard to deal with (and chat does not have user private messages settings thus you cannot control who are going to see them)

here is the LIGO announcement stream youtube.com/watch?v=AFxLA3RGjnc

thus leaky and co.'s advice get me to create a blog and also a chat room to manage that, and now it seems they still managed to work as intended without the flooding problem

...fun story. we've got physics faculty in two buildings right now, and I'm in the other one right now for quite arbitrary reasons

but i just realized that i'm right outside the room where they'll be streaming the LIGO announcement

sooooo

LIGO had another finding after the neutron star merger?

Are we expecting anything more exciting than "yo, we found some more gravitational waves"?

there's a press conference this morning

GPhys already linked the Youtube stream

@ACuriousMind ok so it's really about quantum systems?

@0celo7 Well, the first few chapters are also a nice introduction to classical constrained Hamiltonian systems

But since the title is "quantization of gauge systems", everything is introduced with an eye towards its eventual quantization

yep, waves from collision of two neutron stars

ICECUBE saw it ? :o

that would be news even if it was only ICECUBE news

"Thank you NSF 😭"

hmm, so a > 35s signal, and it is not sure what it is. Could be a neutron star, a blackhole or something else...

GW170817

gamma ray burst measurement suggest it is a neutron star merger. So that means, if neutron stars merge, they can release gamma ray jets

But one question that more interested me is that is the merged object still a neutron star?

i'm trying to get to the paper for this event, doi:10.1103/PhysRevLett.119.161101.

so far, no luck. i suspect i'm not the only person looking it up :)

@Secret There was a Nature article on this signal a few weeks ago (at that point still only a rumor) : nature.com/news/…

and it includes the following paragraph: "Details of the gravitational waves at the time of the collision and in the following instances could also reveal information about the structure of neutron stars — which is largely unknown — and whether their merger resulted again in a neutron star or in the formation of a new black hole." (emphasis added)

so it sounds like no one knows the answer yet.

it'd be a good question for the Q&A, though

Now that's interesting. Given how the black holes detected by LIGO are so massive (30, 60 solar mass) this neutron star data might give us more information on under what criteria will neutron stars became too massive to stay as neutron stars

apparently they're going to answer questions from the Youtube chat

I've asked this question on there: "@LIGO Virgo Do we yet have any idea whether the result of this merger was another neutron star or a black hole?"

here's hoping that'll elicit a response :)

(I don't know if they're collecting questions now or if they'll wait until the actual Q&A sessions, though)

one person in that chat has indicated that the data won't tell us about the result of the merger, which would be disappointing

I'm still hoping it'll come up in the Q&A

where's the link to the LIGO chat cause the life stream that GPhy gave us seemed to have it disabled?

this one: youtube.com/watch?v=mtLPKYl4AHs

no clue why there's two differen streams

warning: it's a public Youtube stream, so there's a lot of idiots

I can see there are many chinese people interested in talking about the neutron star mreger

looks like they're taking YouTube questions now. hoooope

and for some funny reason, some of these thought the press conference is about aliens

and a couple others said it is not

it's a public youtube stream on science. that attracts both science people and crackpots like moths to a flame

ah, someone seems to have asked a similar question!

"they're taking YouTube questions now" - this statement fills me with dread :P

"It could either be one of the heaviest neutron stars ever seen, or one of the lightest black holes ever seen." -Shoemaker (I think)

well, i suspect they'd only bring up questions that'd be at least somewhat sensible

so while the person monitoring the stream chat will have to deal with the horror, I doubt any of it will show up in the press conference

Actually, a question by Greg was addressed, and he also asked about the end state of the merger, and shoemaker give the above comment

yep, that's what I was getting at

I guess a follow-up question re: "what's the end state of this merger" would be how much signal, if any, is given off after the merger.

i'm guessing there's really not any, which is why it's hard to tell what the end state is

Uh what?:

> gakki yui​@LIGO Virgo Can gravitational waves be used to travel through time?

How on earth did peple have such ideas

If there’s a dumb crackpot question, someone will ask it

That’s pretty much a law for these settings

I asked one if the grad students here about the end-state question, and he confirmed that they didn’t see any signal after the merger

He did indicate that, in principle, the resulting object should be spinning and therefore could produce a gravitational wave signal

But it’d be a lot weaker than the collision

So getting an answer to the end-state might require both better signal sensitivity and some luck

Probably too weak to fall within the detection window of LIGO, but we'll see

It will be interesting if the end state is neither a neutron star nor a black hole, but recalling the brief theory stuff I read in the past, that seems highly unlikely

Right. And that window should get better as they improve the experiment

@Secret Frankly, a lot of what you post here on time travel and such looks pretty much like that question.