The h Bar

3:17 AM

While solving questions on calorimetry particularly on state conversion and temperature of equilibrium

On questions on temperature of equilibrium equilibrium for example ice at -20 degrees celsius and of particular weight is kept with water of particular temperature in particular weight and both are isolated

What my teacher does is to bring them both to common state such as water or ice

If there is excess of heat loss or heat in then she uses it to raise the temperature of the state

I am not sure how this can be possible

Is it due to the fact that the state and temperature changes are reversible

example question is 10 gram ice at -10 degree Celsius and 50 gram water at 40 degree Celsius are kept together find the temperature of equilibrium

FakeMod

4:24 AM

24 hours ago, by FakeMod

Both the independent variables used while generating the phase space are supposed to be canonical conjugates. Is this statement correct? (I hope yes)

Nike Dattani

4:57 AM

If anyone is interested in statistical mechanics applied to protein folding:

3

Q: DeepMind just announced a breakthrough in protein folding, what are the consequences?

There was some recent media reporting about a purported Google breakthrough on applying machine learning techniques to tackle the protein folding problem, as told for example in this news article, DeepMind AI handles protein folding, which humbled previous software. Unfortunately there is not muc...

Secret

5:14 AM

The Maths of General Relativity (2/8) - Spacetime velocity

►

This guy has potential

I wonder how he will tackle tensor mathematics

John Rennie

6:59 AM

@FadedGiant :-(

Definitively the end

Prateek Mourya

8:35 AM

@Secret eugen khutoriyansky made a video on tensor and thier use in gr

M. Çağlar TUFAN

10:43 AM

hey everybody

i have a simple but quite interesting question

This is a system of 3 point charges

consider that we have a test charge on the y-axis

it's asked me to find the V(y) potential function, charge is moving on y-axis

we should be able to calculate potential due to each charge as $V_1(y)$, $V_2(y)$, $V_3(y)$ and their sum should give us the asked function $V(y)$

Am I correct?

We know that the potential due to middle +q charge is $V_2(y)=k\frac{q}{y}$

I tried to find the potential due to left hand side charge using $V_ba=-\int{\vec{E}\cdot d\vec{l}}$

Kenshin

11:20 AM

Thanks @JohnRennie

John Rennie

@Kenshin hi :-)

Kenshin

how's 2020 treating you

John Rennie

It's been an interesting year :-)

Kenshin

@Kaumudi how are you

@JohnRennie any idea what caused the Havana Syndrome?

John Rennie

12:06 PM

@M.ÇağlarTUFAN potentials just add:

If you take the point P that is a distance y away from the middle charge then the potential due to the middle charge is +kq/r, and the potentials due to the other two charges are -kq/r.

Where r² = d² + y²

You just add up the three potentials so the total potential is:

$$ V(y) = \frac{kq}{y} - \frac{2kq}{\sqrt{y^2 + d^2}} $$

Nihar Karve

12:41 PM

What kind of maths do you guys like?

Because I'm dead bored with group/rep theory and diff-geom right now, looking for something to explore

bolbteppa

1:07 PM

Hahn-Banach theorem

Some functional analysis and measure theory maybe

RewCie

3:50 PM

Just In: UK, Russia to start mass vaccination of COVID19

Emilio Pisanty

that's extremely pleasing

3

Nihar Karve

:O

hold on, lemme go upvote a post ;)

JMac

4:42 PM

@EmilioPisanty You'll have to tactfully balance your answers, answer downvotes, and bounties now to keep it 111,111 as long as possible.

Ryan Unger

4:54 PM

@ACuriousMind is CP2077 actually coming out this time

Will it be horribly buggy

Nihar Karve

@bolbteppa functional analysis is a great idea, thanks

ACuriousMind

@RyanUnger yes to both :P

I think they absolutely won't delay it until after christmas if they have anything to release at all

Ryan Unger

Are you buying day one?

ACuriousMind

probably yes

I'm already spending my willpower on not buying several early access titles, I have no willpower left to resist buying this one the moment it comes out

Ryan Unger

Lol yeah it’s gonna be “officially” released but we’ll be beta (alpha?) testing it

JMac

5:03 PM

I was going to get it for PC, but I'm going to wait a bit and get a PS5 now I think. I decided to sell my Switch and games last week and got $600 store credit at a local place, so I said screw it and went on the list for a PS5, so I'll probably be playing that in like a year.

Ryan Unger

I’ll get it on PC but my GTX 1080 is struggling

I want a 3080 but i probably need a new case

RewCie

PS5 won't get launched in India :-(

JMac

I only have a 1060 and a i5 6500 too, so a modern game like that would run real bad on my PC probably, whereas presumably they will at least have good console ports.

Ryan Unger

I should have bought a case on cyber Monday

JMac

Is yours just too small right now?

Ryan Unger

5:12 PM

Yeah I think it’s a mini ATX

I have a very nice motherboard though

so if I got a bigger case I'd still have the tiny mobo

I think a 3080 would just be too long for my current case

RewCie

RTX 3080? That's a beast!

JMac

Makes sense. A small motherboard with a huge brick jutting out would be pretty funny.

Ryan Unger

yeah

JMac

The nice thing is big cases still have mountings for the small factor motherboards too, so at least it would be basically as straightforward as buying a case and the GPU and moving everything over, instead of having to like mess with a heatsink and everything.

Ryan Unger

yeah I think it would be fine

also my current case doesn't have great cooling

JMac

5:20 PM

My case has glass panels in front of all the fans, and just strips on the side let air through. I thought it was going to make my CPU a lot warmer than my old case, but it didn't make a difference. It might just be because there's a ton of fans to force airflow anyways.

geocalc33

Is there a locally ringed space approach to semi-riemannian manifolds?

ACuriousMind

@RyanUnger eh, I kinda hope CDProjekt don't let us down that terribly, but we'll see

@geocalc33 probably not, see mathoverflow.net/q/56833/157071 and its linked question

Nihar Karve

@Charlie I know the answer to your Cauchy integral formula question, but I'm on mobile so it'll take me a little while to write out

Ryan Unger

why would you want to turn riemannian geometry into algebra

geocalc33

@ACuriousMind why do you say probably not?

ACuriousMind

5:35 PM

@geocalc33 because if you look at the question I linked, it has no answer, and in the linked question there's a characterization in terms of sheaves of vector spaces, not rings

geocalc33

oh okay gotcha

ACuriousMind

it's hard to see how one would encode the metric purely in terms of the rings of continuous/smooth/whatever functions

ACuriousMind

5:47 PM

@RyanUnger masochism :P

Charlie

@NiharKarve why do we have $z+E_p$ on the denominator of $g(z)$?

geocalc33

@RyanUnger Someone might want to gain new insights into both geometry and algebra by porting information between the two disciplines

Charlie

ohhh wait no maybe I do see

Nihar Karve

@Charlie I mean, you can take it to be whatever you want as long as g(E_p) is the advanced bit

Charlie

ok I see the trick they've used, thanks for your answer

Nihar Karve

6:00 PM

No problem :)

Charlie

6:13 PM

I actually have a related follow-up question, why do we even close the contours in the first place when evaluating the $p^0$ integral?

Is it because when we take the radius of the "closing loop" to $R\rightarrow \infty$ it's contribution vanishes and we're just left with the integral along $\Bbb R$?

or rather, the integral along $\Bbb R$ that avoids the poles

Nihar Karve

In general, yes, which is why contour integration is so powerful

Charlie

wait that's a general result?

Nihar Karve

Take a look at the example on the residue theorem wikipedia page

You close the contour up or down depending on whether its exp(-i...) or exp(i...), so that the contribution along the curve vanishes

Charlie

oh I see, ok ty

newUser

7:11 PM

Does anyone know an example of a reference frame for the complex momenta of two identical massive (on-shell) particles and one massless particle? Taking momentum conservation into account

it seems an easy question, but I am able to find a solution

123

Hi All.

Nike Dattani

7:51 PM

I might have gone overboard with this one:

4

Q: How many spin states do Cu+ and Cu2+ have and why?

I know an electron can have two spin states, "spin up" and "spin down", but recently I was asked how many spin states do $\ce{Cu^+}$ and $\ce{Cu^{2+}}$ have, and why? Does anyone know the answer? Thanks.

transition-metals from-chem-se spin-orbit-coupling spin metal-complexes

Unfortunately for me, I don't know any undergrad-level science. The only science I know is at the research level, and the NIST database shows hundreds of experimentally observed states. If one of you know what the undergrad textbooks say about what spin states are allowed, please add the answer for this poor soul who thought they would just get an answer to their homework question.

vzn

11:59 PM

6

Q: New Stack Exchange site proposal: Computational Fluid Dynamics!

There's a proposal at the moment for creating an SE site for computational fluid dynamics, and if you would like SE to add a site for this topic, I suggest you follow the proposal, ask some example questions and upvote five questions because the biggest barrier for getting past the first stage in...

discussion sponsorship-and-advertising proposal-for-new-site related-stack-exchange-sites

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