The h Bar

ACuriousMind

16:03

@Slereah I've kept my room cool by not opening the blinds or any windows while the sun is shining :P

Slereah

Same here

Still too hot

Anonymous

You don't use ceiling fans in France?

Anonymous

Or table fans?

Anonymous

They are much cheaper and more effective during summers

ACuriousMind

@Blue I've never seen a ceiling fan in real life

It's something they have in movies to me :P

Anonymous

16:05

@ACuriousMind Heh :P Standing in front of a table fan during summers is bliss XD Or sleeping under a ceiling fan on hot summer nights *_* :D

Anonymous

(And they cost only around 20$)

AccidentalFourierTransform

in Germany its always cold so who cares

Anonymous

Oh yeah, that's true :P

John Rennie

@ACuriousMind That does stop the sunlight heating up the surfaces in your room that it illuminates, and therefore stops those surfaces heating the air in your room. However it's only partially successful as it does heat the blinds. You really need blinds outside the windows to be fully effective.

ACuriousMind

@JohnRennie The blinds are outside

John Rennie

16:12

Aha. In the UK we'd probably call those shutters rather than blinds.

Shutters are very rare in the UK because it's only hot enough to need them for a handful of days a year :-)

ACuriousMind

The finer English distinctions of window obstructions admittedly elude me ;)

@JohnRennie Huh, they're pretty common for newer houses here

John Rennie

@ACuriousMind I'd say shutters are virtually unknown in the UK. I'm a bit surprised they are common in Germany. Do they have other uses e.g. keeping the heat in during the winter?

Anonymous

Here most houses have curtain or drapes (mostly thick cotton ones) instead of shutters/blinds. But that blocks the sunlight almost completely.

John Rennie

I get this all the time. I comment saying we don't answer homework questions and the OP replies please answer my homework question:

Oh thanks! But can you explain me how to solve this please?! — pooza 26 mins ago

Which bit of we don't answer homework questions do I need to make clearer?

Anonymous

The OP doesn't realize that his/her question is homework, maybe :P

John Rennie

16:19

@Blue inside the Windows? In that case my original comment applies. The sunlight will heat the curtain so the curtain gets hot and heats the air in your room.

Though I guess most curtains have a reasonably low thermal conductivity.

Anonymous

@JohnRennie Yeah, inside. However I think that it is still more effective compared to shutters/blinds. We have blinds in our balcony but that is the hottest room in our whole house. I guess thick curtains are better insulators. (Most of them are double-layered i.e. having a layer of air in between).

John Rennie

@Blue Yes, the side of the curtain facing the window will get hot, but if the thermal conductivity is low enough the side facing the room will stay cool.

Anonymous

@JohnRennie Yup, exactly

John Rennie

It is so rarely very hot in the UK that we Brits mostly don't bother :-)

We just complain bitterly on the few days a year it gets up to 30ºC :-)

Just win baby

The Atlantic ocean makes a huge difference.

Anonymous

16:28

lol, I sometimes wish I lived in a cooler place. During the summer months it becomes almost impossible to walk on the roads. Temperatures of 45-50 degrees C is quite common here.

John Rennie

When I was a young boy we lived in the Sudan (my father worked there) where the summer temperatures were similar. We used to come back to the UK during July and August and only go back in September when the worst of the heat had passed.

It peaked at 42C in Khartoum today according to that nice Mr. Google. However the relative humidity is very low so the heat isn't so hard to live with.

Just win baby

You can fry an egg on the road with those temperatures.

Anonymous

Humidity is the real devil. 45 degrees is tolerable when you are not sweating like a pig.

John Rennie

The RH in The Sudan is very, very low. The whole country is basically a desert with the Nile running through it.

dmckee

@Blue You sweat even when it's very dry: the moisture just doesn't stand on your skin or even collect in your clothes.

A fact which makes it very easy for dehydration to sneak up on you.

John Rennie

16:43

@dmckee even salt deficiency if you lose enough salt in sweat. We used to have a jar of salt tablets in case anyone got salt deficient.

John Jack

Hello all

Just win baby

Hello

Humidity prevents the cooling effect of your sweat evaporating off your skin.

John Jack

In a text I am using it shows the quantization of a single mode electric field in a cavity by showing that the Hamiltonian is analagous to the Hamronic oscillator and then basically just shows that the energy of hamrnoic oscillator is quantized. It then considerd the electric field as an operator:$$\hat{E_x}(z,t) = (\frac{2 \omega^2}{V \epsilon_0})\hat{q}(t)\sin(kz)$$ using Maxwell's equation we find the corresponding magnetic field operator in terms of $\hat{p}(t)$.

Sid

I laugh when Brits complain about hot weather..

John Jack

Do we consider $\hat{p}$ and $\hat{q}$ as Hermitian operators, since we equate them with the position and momentum operators (as they are in the Harmonic oscillator case in QM)?

ACuriousMind

16:55

@JohnRennie I don't think so, I'm not sure why we like them so much

Just win baby

...we're so used to the cool ocean breeze.

Emilio Pisanty

Hey @ACuriousMind @dmckee & other regulars and mods, I'm slightly bothered by this but not sure how to approach this

In my opinion you might have misjudged your audience in your last sentence, :). What are your ideas about it, that's what people really want to know. — Countto10 2 hours ago

I think this is representative of a pattern of distinctly less-than-helpful comments by that user

Not actively bad

but patronizing in some ways, particularly when OP is a new user

ACuriousMind

@EmilioPisanty Have you tried responding to some of these comments and explaining why they're not helpful?

Emilio Pisanty

@ACuriousMind I keep feeling like it would derail the conversation

ACuriousMind

@EmilioPisanty Maybe reply once and tell them if they want to discuss that further to take it to chat/meta?

Just win baby

17:00

I see no malicious intent.

Emilio Pisanty

@ACuriousMind Yeah, I've looked for an occasion where it doesn't derail things too much and I haven't found it

@Justwinbaby It's not malicious intent

I can't quite pin down why it bothers me, tbh

What do you think happens, after reading this physicsclassroom.com/mmedia also drawing diagrams can help you — Countto10 yesterday

maybe gets the pattern better

Just win baby

Sure it's "patronizing." But I've seen a lot worse.

Emilio Pisanty

@Justwinbaby sure

Anonymous

@dmckee Ah, right :)

Emilio Pisanty

which is why I hesitate to act on it

ACuriousMind

17:02

@EmilioPisanty Maybe what bothers you is that these comments are "Please show some effort" but sound more as if the commenter is actually interested in OP's thoughts than improving the question?

John Rennie

@EmilioPisanty to be fair I think Countto10 means the question is homework like, and is prompting the OP to put more effort in.

John Jack

@ACuriousMind What do the photons correspond to when you describe a quantized single mode field (as I described above)?

ACuriousMind

@JohnJack Where above?

Sid

High Humidity is unbearable when the temperature is >40 degree celsius

AccidentalFourierTransform

four self-answers in a day

John Jack

17:04

@ACuriousMind :) A few messages above my last message.

AccidentalFourierTransform

that has to be a record or something

Emilio Pisanty

@JohnRennie for sure, they're obviously trying to help

John Rennie

@ACuriousMind this presumably

Just win baby

@EmilioPisanty just observe to see if he gets worse.

Emilio Pisanty

I'm probably overbothered by this, I'll put it back on the back burner

@JohnJack what do you mean by "correspond to"?

Just win baby

17:06

If he starts to talk down to an OP then that's a different story.

John Jack

@EmilioPisanty I mean how does it enter into the description, what does a 'photon' refer to in this description?

Emilio Pisanty

@JohnJack "photon" is a weird word, it's a good deal more helpful to think in terms of single-photon states

so a single-photon state is the $n=1$ Fock state of the harmonic oscillator

AccidentalFourierTransform

ewwww

I wish those words were forever banned from physics books/discussions

Emilio Pisanty

@AccidentalFourierTransform what?

AccidentalFourierTransform

"single-photon state" ew 1/2

"Fock state of the harmonic oscillator" ew 2/2

Just win baby

17:11

^joke

John Jack

@EmilioPisanty Is it what is commonly called a number state? The eigenstate of $\hat{N}$ where $\hat{H} = \hbar \omega(\hat{N} + \frac{1}{2})$?

Emilio Pisanty

@JohnJack yes

John Jack

@EmilioPisanty What's so important about $n = 1$?

Emilio Pisanty

@JohnJack you asked for single-photon states

well, to be fair, you didn't

an $n$-photon state is the $n$th number state of that harmonic oscillator

Just win baby

One is a good place to start counting :-)

John Jack

17:19

@EmilioPisanty Oh okay thanks.

@EmilioPisanty Do you see it as photon particles with higher energy or is that a silly way of modelling it...do you just think of it as eigenstates?

Emilio Pisanty

@JohnJack For me, photons are, fundamentally speaking, a property of the excitation statistics of a given radiation field.

It's very easy to say "ooooh, look, photons are doing their wave thing" while pointing at, say, double-slit interference fringes, but that's completely misleading

John Jack

@EmilioPisanty Yeah that's the kind of idea I am still working with.

Emilio Pisanty

A photon is an excitation built on top of the classical mode, and the fringes belong to the classical mode, so the fringes are pretty boring hum-ho unsurprising phenomena

The truly quantum interference phenomena to do with photons are the ones that happen on the Hilbert space of the harmonic oscillator

0celo7

@EmilioPisanty Are you familiar with X ray spectroscopy?

Emilio Pisanty

the most notable of which is the dip in Hong-Ou-Mandel interferometry

Hong–Ou–Mandel effect

The Hong–Ou–Mandel effect is a two-photon interference effect in quantum optics which was demonstrated in 1987 by three physicists from the University of Rochester: Chung Ki Hong, Zhe Yu Ou and Leonard Mandel. The effect occurs when two identical single-photon waves enter a 50:50 beam splitter, one in each input port. When the photons are identical they will extinguish each other. If they become more distinguishable, the probability of detection will increase. In this way the interferometer can accurately measure bandwidth, path lengths and timing. == Quantum-mechanical description == =...

@0celo7 some aspects. Why?

0celo7

17:38

@EmilioPisanty I am trying to figure out which beamline at APS I want to use but there's like 30

and so many spectroscopy techniques

Emilio Pisanty

@0celo7 wut

what's a mathematician like you need from APS?

=P

0celo7

@EmilioPisanty I'm an engineer

Emilio Pisanty

@0celo7 no, seriously, though, what do you want to do at APS?

0celo7

@EmilioPisanty Roughly, determine oxidation states in a powder I obtained

My Raman data doesn't line up with a simple mixture of the component oxides

Emilio Pisanty

@0celo7 hmmmm, yeah, I might not be the best person to ask that to

0celo7

17:42

So there's something going on with the alloying, or maybe some unstable oxide is existing stably in the mixture

X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) is a surface-sensitive quantitative spectroscopic technique that measures the elemental composition at the parts per thousand range, empirical formula, chemical state and electronic state of the elements that exist within a material. XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons that escape from the top 0 to 10 nm of the material being analyzed. XPS requires high vacuum (P ~ 10−8 millibar) or ultra-high vacuum (UHV; P < 10−9 millibar) conditions, although a...

@EmilioPisanty I think this is what I need but APS is telling me only one beamline has that.

It seems far too routine for that.

There's 30 beamlines...and it's not some crazy technique.

Emilio Pisanty

@0celo7 maybe there's a smaller synchrotron closer to you that can also do it

0celo7

17:59

@EmilioPisanty We're writing the proposal now but I can't figure out which beamline

I think our in-house one can do it

But for our grant we are encouraged to use other people's stuff

@Loong Ah, master Chemist

See above

AccidentalFourierTransform

So, to be clear, your question is whether or not discussing Tegmark's approach to "reality" is asking too much of a physics AMA? That seems a bit weird. I figured you'd want to discuss their approach or an aspect of it. But if you really just want to ask if we're capable of discussing it in an AMA session, then I'll answer that during the session. But seeing as this is the only AMA session I see myself having, wouldn't it make more sense to just ask a question within the topic and see where it goes? It's the whole "don't ask to ask, just ask" thing. — Jim 7 hours ago

lmao

DukeZhou

19:04

Is anyone else excited about the new kilogram? I know I am!

Anonymous

19:24

@DukeZhou I just read about it just now. The concept seems pretty interesting. :)

Anonymous

Err...grammar mistake there ^ (pardon me) :P

DukeZhou

19:41

@Blue :)

Emilio Pisanty

@DukeZhou a bit, yeah

32

Q: What are the proposed realizations in the New SI for the kilogram, ampere, kelvin and mole?

The metrology world is currently in the middle of overhauling the definitions of the SI units to reflect the recent technological advances that enable us to get much more precise values for the fundamental constants of nature than were possible when the SI was drawn up. This has already happened ...

;-)

DukeZhou

20:06

@EmilioPisanty in my field, people were super excited about AlphaGo, but I still feel like your field gets the best breakthroughs: Higgs boson, Gravitational Waves, exoplanets, ect. :)

0celo7

23:00

@ACuriousMind is the smith in Novigrad named after the one from Kill Bill?

ACuriousMind

@0celo7 Hattori? I think so, yes (though the name itself is orignally that of a sorta famous Japanese samurai)

0celo7

23:20

@ACuriousMind do you have an ASUS monitor?

ACuriousMind

@0celo7 Uh...yes, actually

0celo7

@ACuriousMind Do you understand the preset modes?

I was on game mode but I just discovered it was making everything ugly

I'm now trying "scenery"

Dawood ibn Kareem

@Abcd Which part?

ACuriousMind

@0celo7 Not really, but it's my second monitor, so it's mainly displaying text like this chat, not graphics

0celo7

Double monitor bourgeoisie

ACuriousMind

23:25

Its colors always have seems a bit off, but that could also be because it's a bit old - I got it from a friend who didn't need it anymore

0celo7

@ACuriousMind I thought it was too bright, games looked too cheery

Now everything looks dark and gloomy

macco

23:52

any good book suggestions on anything non-fiction?

Just win baby

do you mean textbooks?

0celo7

@BernardoMeurer hola

I'm messing with monitor settings but can't get GTA 5 to play properly

my GPU isn't running on max but my FPS is <60

Just win baby

en.wikipedia.org/wiki/Gödel,_Escher,_Bach @macco

Bernardo Meurer

@0celo7 See if you have Vsync enabled

0celo7

@BernardoMeurer I do

it's going between 30 and 60 and everything in between

so the v sync is not working

Bernardo Meurer

23:59

Yeah, disable it

never enable vsync

unless you're experiencing tearing

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