The h Bar

12:01 AM

I also randomly insert (using an if-else block with a randomized condition) minus signs in code for fun...I like to watch the world burn.

danielunderwood

12:12 AM

GLaDOS thinks you're a horrible person

►

@ACuriousMind since you seem to know of every language under the sun, have you heard of elixir? I've heard it a couple times this week and now I'm curious

David Z

12:25 AM

@enumaris Yeah apparently! There have been a lot of changes in the recruiting team since I applied. Anyway your application is still in the system. I'll email you if I find any info to share.

enumaris

12:36 AM

@DavidZ cool thanks! :D

danielunderwood

Actually the only complaint of the team I interviewed with today was that the HR process took too long. Maybe it's a common thing these days

Sir Cumference

1:40 AM

@danielunderwood Huh, I was thinking of portal when I opened the chat

Spooky

danielunderwood

Always gotta be thinking with portals

Secret

3:15 AM

I don't just think in terms of portals. I think in terms of bundles of timelines

Dvij Mankad

4:29 AM

Hi. I am trying to understand the actual degrees of freedom that the metric has in relation to the fact that the graviton is a spin 2 particle. In my understanding, subtracting the Bianchi identities from Einstein equations, we are left with 6 independent equations which determine the 6 physical degrees of freedom of the metric because out of the 10 independent metric elements, 4 are not physical as they correspond to diffeomorphisms.

But this answer seems to suggest that the redundancies due to the Bianchi identities and the diffeomorphism invariance should be added for some reason and thus, we end up with only 2 actual degrees of freedom. This doesn't sound right to me. physics.stackexchange.com/a/74330/20427

Also, I would expect 5 actual degrees of freedom due to spin 2 nature of graviton--neither 6 nor 2. I realize that due to the masslessness, we should actually get only 4 helicities instead of 5 spins but I expect to get to 5 degrees of freedom classically just like we get to 3 independent degrees of freedom of vector potential for electrodynamics classically despite the fact that the photon has only 2 helicities. I am sure I am making a lot of mistakes here so any suggestions would greatly help!

bolbteppa

5:05 AM

@DvijMankad slide 2 particle.physics.ucdavis.edu/modernsusy/slides/… shows how to get from 16 to 2 through vielbein's

Page 2 of arxiv.org/pdf/1706.08140.pdf also brings up this constraint + eom argument and compares to the massive case

vzn

5:26 AM

Physicists create ultra-hot drops of 'quark soup' that dominated the very early universe / astronomy.com

> However, this new study suggests that at high enough energies, the tiniest particles in the universe can behave and flow like an idealized, near-frictionless liquid.

Stephan

6:01 AM

Hello, I'm currently studying the effective action in QFT and I don't think I fully understand what is called "classical field", aka the VEV of the field in the presence of the sources. Does anyone know a good resource/book for this?

Physics Meta

7:53 AM

0

Q: Question about notifications

Alice posts a question. Bob posts an answer. I want to comment on Bob's answer, and I want both Alice and Bob to be notified of the comment. Therefore I type something like "@Alice: As @Bob said....". I then get a pop-up notice that says I can have only one @-sign per comment. Fine. The...

support

Slereah

8:29 AM

new hat

John Rennie

I only have the one hat so far - for reviewing. But then I hardly ever answer questions these days ...

John Rennie

8:47 AM

I spoke too soon, I just earned a waffle :-)

Slereah

perfect for breakfast

Mithrandir24601

@JohnRennie Ooh, sounds like a secret hat

John Rennie

@Mithrandir24601 it is :-) I have absolutely no idea what I did to get it.

Mithrandir24601

@JohnRennie The namesake is presumably Waffles

John Rennie

9:24 AM

The secret hat list is here but so far no-one has worked out what the waffles hat is for.

user55789

9:37 AM

I have a simple question about the effect of some operator

John Rennie

@danielunderwood the Windows market was (actually still is) much, much larger than the *nix market so in general Windows programmers weren't fussed about getting their code to compile on other systems.

Where you need your app to run on multiple OSs you'd use some ifdefs but mostly you'd use a development environment that allowed the platform independent code to be shared and the platform dependent bits to be implemented in seperate source files.

user55789

I don't see how the second equality holds, i.e. before and after the second equals sign??

Is this normal?

John Rennie

@enumaris it is just the latest step in our government's attempts to make British a synonym for farcically incompetent.

user55789

It's not so much about the way the operators work and give the eigenvalue $\xi_k$, it's more about how i only have the operator before the $a^\dagger_k$?

Captain Bohemian

9:58 AM

in winter the worst weather circumstance is persistent raining and overcast sky, which makes no stars to watch at night and brings depressing air. The lowest air temperature I have experienced here is 4 C, but it doesn't occur every winter. The only storm here is typhoon, which mostly occurs in summer.

Captain Bohemian

10:13 AM

@JohnRennie last time you told me about excitation of fields, which recalled me the creation and annihilation operators, which I learnt in nonrelativistic quantum mechanics. Now I found in quantum field theory there are also creation and annihilation operators in en.wikipedia.org/wiki/Normal_order.

John Rennie

@CaptainBohemian I was talking about quantum field theory ...

Slereah

There is

a Link

between the two

John Rennie

@Slereah that's simply harmonic

Slereah

yes

John Rennie

Helpful comments ' r ' us

2

Slereah

10:28 AM

I mean it's in every QFT book

Slereah

12:11 PM

what is up with the special conformal transformation anyway

Every other conformal transformation is like

fine

then you see the special conformal transformation and what the hell is that

mick

0

Q: Physics mystery : why does it rotate?

In The beginning this thing was floating still and the candle was out. Then someone lit the candle and the flame somehow Made the object spin on the water. See the picture. I know a little bit about thermodynamics and a bit about electromagnetism. But not The combination. Is this due to ma...

electromagnetism thermodynamics classical-mechanics rotational-dynamics thermoelectricity

John Rennie

12:32 PM

0

A: Physics mystery : why does it rotate?

What your GIF doesn't show is that the bottom ends of the copper tube are angled: The toy is known as a tea-light engine and Googling this will find you various sites describing it. The copper tube is full of water. When the candle heats the tube the water at the point where the heat is applie...

Captain Bohemian

1:57 PM

I think it should be harder for mathematicians than physicists to find a friend outside school.

user55789

2:12 PM

@CaptainBohemian Should I infer that the contrary holds? :D

Slereah

He wants a friend

Captain Bohemian

@user55789 maybe it's so, but I don't really know because I haven't had much experience with interacting with mathematicians in real world. But I have an experience contrary to my imagination--people from society department are very unsocialized in that they didn't want science people to use their equipments.

user55789

You mean the soft sciences?

Captain Bohemian

no

physical sciences

I used to be in an applied science research institute which borrowed the building of society department as our office because this institute has no their own building, and the people from society department were very unfriendly to us like they were unhappy with our using their space. For example, when their food in refrigerator disappeared, they suspected it's us who stole it, but not their own people. After their food disappeared for several times, they forbad us to use their refrigerator.

user55789

2:42 PM

How does this relate to science people making friends ouside school?

Captain Bohemian

I just feel mathematicians study so abstract issues which have no much relation with what happen in real world so that most people outside math fields don't understand those issues, so how could they find a person outside school understanding what they are talking about?

user55789

It's no different for physicists, is it?

Captain Bohemian

the topics studied by physicists are less abstract than issues in maths and sometimes some phenomena occurred in daily world can be explained in physics laws; I have seen the media invite physicists to explain something for the general public.

Slereah

it depends a lot on the field you study

if you're making nanomachines it's fine

if you're trying to compute the VAV of some string theory it's trickier

enumaris

4:47 PM

hmmm

welp, the NHL event was pretty nice...apparently SAP is in the process of building an innovation center here in LA

the private suite was not as fancy as in the movies though...lol

danielunderwood

5:04 PM

The one I was in wasn't particularly fancy, but it had food and alcohol provided which is about all I can ask for in a stadium

enumaris

same...but I don't drink alcohol so I guess it was much cheaper to host me lol

I just got a ginger ale

danielunderwood

Well unfortunately I was under 21 at the time anyway

I do approve of the ginger ale though. That's about the only soda I drink

enumaris

XD

I felt like a freaking salesman peddling my NLP wares yesterday lol

2

gave the whole "I work on NLP" spiel like 4 times last night

Anonymous

I made a new Why are images of text, code and mathematical expressions discouraged? thread on Meta SE. In case anyone has points specifically relevant to the math/science sites - like Physics SE, in mind, please go ahead and add it there. (cc @EmilioPisanty)

Anonymous

0

Q: Why are images of text, code and mathematical expressions discouraged?

Often I see new users posting images, containing the text of the question they were intending to ask, or a part of it. This is especially true for the science and math based sites where new users don't know how to use MathJax. I tried searching through the previous questions on Meta SE, but could...

discussion images code

danielunderwood

5:18 PM

Brave man talking about ML in public

They may start asking you questions about AI

Neat washington.edu/news/2018/12/11/sensor-bees

enumaris

The head of the center seemed interested in following up

I followed up by sending him a message on linkedin

we'll see if anything comes of it lol

danielunderwood

Of the SAP center?

Maybe you could become a COBOL NLP guy

enumaris

yeah head of the SAP Center

danielunderwood

You could be the first and last one

enumaris

it seemed like they were mostly interested in software engineers though that's true

but they wanted to do "research into the next 5-10 years" and their current goal is a "smart hospital"

head of this Newport Beach Innovation Center

It sounded like their current openings are very much software based. The guy said he's looking for software engineers and "architects"

danielunderwood

5:31 PM

Hey some of my work stuff is in the direction of IoT devices in medicine...it's just being done in a way that's less than ideal

enumaris

maybe you can apply lol

They did say they have 1 data scientist and 1 more was joining soon

but they said the data scientist was very heavily math/stats focused

not really ML focused

danielunderwood

We should all join SAP and start a physics uprising

Also you may be past this level, but it's neat to me github.com/GokuMohandas/practicalAI

enumaris

lol

danielunderwood

Also jax has had a lot of documentation added since I linked it

I'm going through all the newsletter emails I've ignored over the past week...fun times

enumaris

I should just tell that VP to make me the head of strategy at that innovation center

I'll build him a deep learning system that reproduces duck quacking sounds

danielunderwood

5:40 PM

lol there was a kaggle competition about turkey sounds at Thanksgiving

enumaris

I think it kind of depends on how out of the box thinking they want to do

Cus obviously their current thought process is "get a bunch of software engineers and we'll figure out how to build some software"

but to want to hire me, they'd have to shift a little bit more to the pure research side I think

danielunderwood

Well that's better than the approach of "get a couple interns and keep saying IoT"

Replace IoT with ML, NLP, AI, or your favorite thing

enumaris

the Pharm company was kinda doing that lol

during my interview, he was like "for pure research stuff, we might get a few interns to do a POC and then after POC we'll get a full time resource on it" or something like that