2:02 PM
@Slereah I'm AFK
Will look later.

aight
I'll look up HE for cloos

Hello @Yashas

hi

@yashas why is the weight slightly greater at night than in day?
@

2:14 PM

user228700
@JohnR: Afternoon(?) :-)

Why is $j$ more special than $i$? o0 @Slereah

it is engineer stuff

@Yashas, which of the following is an essential chacteristics of a projectile? a). Initial velocity inclined to horizontal. b). Zero velocity at highest point. c). Constant acceleration perpendicular to the velocity.

2:16 PM
c

d). None of the above

d
D is the best option>next best is C
hmm
C is not right at all
it is completly wrong
a) it is obviously wrong; you can launch it at an angle
b) projectile falling on an inclined plane
c) it would be circular motion if it the acceleration was always perpendicular and constant

@Kaumudi.H Hi. Sorry for the slow response - just making lunch!

user228700
:-) Wokay. What are u making?

2:18 PM
-> is still not clicking in my mind

@Slereah why is the engineer style more special than the [inser word] style?

Where are you @acu

Sorry I can't explain a joke lest it loses it humor

@Yashas, for a motion on a curved acceleration is ; a). >1. b). Greater than or equal to 1. c). Less than or equal to 1 d). <1

I am not doing your homework

2:19 PM
@Yashas, this is not a homework

@Ramanujan where is your attempt at solving the problem?

@Kaumudi.H tortellini with a chicken sauce and black pepper

@JohnRennie What's is written on your RIGHT ALT key?
It says "Alt Cr" or something like that o0

@acu why I got question ban? I didn't asked any questions from 30 days. What are you doing with my account? It is keep going on my profile and returning to chat

2:20 PM
@Yashas Alt Gr

o0

@Yashas, these are entrance MCQs

What does "Gr" mean?

General relativity

Hello @Qmechanic something is wrong with my account

2:21 PM
AltGr (also Alt Graph, Alt Graph, Alt Graph, AltBig text, Alt Car, or Right Alt) is a modifier key found on some computer keyboards and is primarily used to type characters that are unusual for the locale of the keyboard layout, such as currency symbols and accented letters. On a typical, IBM-compatible PC keyboard, the AltGr key, when present, takes the place of the right-hand Alt key. In macOS, the Option key delete has functions similar to the AltGr key. AltGr is used similarly to the Shift key: it is held down when another key is struck in order to obtain a character other than the one that...

user228700
@JohnRennie Eyy, that looks good :-)

@Ramanujan just because a question appeared in a competitive exam does not disqualify it from being classed as homework question
My keyboard ALT key has just "Alt" written on it

@Fawad The question ban is an automatic system that has nothing to do with us moderators (in particular we cannot remove it even if we wanted to). You can find an overview of different version of this ban e.g. in this meta answer

@Kaumudi.H I have now started eating it, and I can confirm that it is good :-)

@Ramanujan The question does not make sense.

2:25 PM
@Kaumudi.H I might have overdone the black pepper a bit though. It's hot! :-)

user228700
@JohnRennie Nice! :-) I think I might be having corn on the cob for dinner tonight.

@Kaumudi.H Mmm, I used to love that as a child but I haven't eaten it for ages.

user228700
Neither have I. My sisters have gone to the beach and there, they sell this so I'm expecting them to bring back some for me and mum.

@ACuriousMind I don't care that post. Let's discuss here. My last question has 2 upvote (+2 is not negative) then why ban?
And 30 days ban is too long

@Fawad : What ACuriousMind said. The question ban does not necessarily have to do with your own actions. It could also be activated by e.g. downvotes on your questions, etc.

2:30 PM
@Fawad What do you mean "I don't care that post"? There's nothing to discuss: The question ban is automatic and no human has any input on it. No moderator imposed your ban and no moderator can lift it. Your only two options are to either improve your existing posts or to wait it out.

@ACuriousMind give me link of help centre where it says question ban.

Hm
Maybe the time orientation business is more to be done by continuity
The timelike character of the transported vector will not change, and by continuity it cannot abruptly change light cone
since it would have to go through the $0$ vector

2:46 PM
If temperature is a function of kinetic energy only, then why do we write specific heat as dq\dT = (dU - W)\dT?
shouldn't specific heat capacity be always 3/2R?
"Temperature is not directly proportional to internal energy since temperature measures only the kinetic energy part of the internal energy, so two objects with the same temperature do not in general have the same internal energy" - hyperphysics.phy-astr.gsu.edu/hbase/thermo/temper.html
o0
"Complications such as these have led to the adoption of a different approach to the concept of temperature in the study of thermodynamics. Schroeder's proposal for a theoretical definition of temperature is:

"Temperature is a measure of the tendency of an object to spontaneously give up energy to its surroundings. When two objects are in thermal contact, the one that tends to spontaneously lose energy is at the higher temperature."(Thermal Physics, Ch 1.)"
I am totally confused.
What is temperature now?
The kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. It indicates the absolute temperature as proportional to the average kinetic energy of the random microscopic motions of those of their constituent microscopic particles, such as electrons, atoms, and molecules, that move freely within the material.
Does fluids include liquids too?

Hi guys, I am trying to search for the most highly voted tumbleweed (i.e. no answers and more than a year old) question in PSE, what should I enter as parameters in query SE?

@Slereah parallel transport preserves angles, no?

### Tavern on the Meta

MY GOD, IT'S FULL OF STARS AND BACKLOG! General friendly chit-...

@0celouvsky It preserves products yeah

2:55 PM
@Secret Technically, that's not a tumbleweed if it has votes at all

So $g(\tau_p, \tau_p)$ is constant along the curve
Hence always timelike

@Slereah and time orientation is defined by an inner product
so what exactly is the issue?

Well yes, but you see

@Secret If you just want the highest voted question with no answers, then that's what the "unanswered" tab is for

$\tau_p$ is parallely transported
But $\tau$ isn't

2:56 PM
Isn't it that one string theory question

Ok I see. Thanks guys

$\tau$ is just a vector field

where the guy says the method was proven to be wrong but people still use it because it "works"

Although I think the continuity argument works
So that's probably fine

user228700
@JohnR: I've been watching a few vlogs of a person named Jake Wright who used to attend Queens college at Cambridge and my my, the sort of traditions u have! :-o

2:57 PM
by continuity the tangent vector stays in the same light cone

@Kaumudi.H I wouldn't take it too seriously. A lot of the weird traditions are really optional and people only take part if they want to.

user228700
I had absolutely no idea that the May Balls go on till 6 AM!

wonder what the globalists are doing to him

I've never been to a May Ball as a paying guest, but I have worked at one.

user228700
Ooh, are students allowed to work there?

2:59 PM
Yes.

user228700
And then I found out about something called "formals" in which you dress up really nicely and have dinner with your profs. and supervisors, etc. And so.much.drinking!

To keep costs down they often use students as serving staff etc.

Maybe that may even work for the scalar product itself
Both $\tau$ and $\tau_p$ are continuous vector fields, so $g(\tau_p, \tau)$ is too
And again it can't be $0$

@Kaumudi.H it's just an excuse for a party :-)

So it will always be negative since it is negative at $p$

3:01 PM
You do have to wear gowns for dinner.

user228700
^ That's one of the more absurd (and fascinating) traditions I observed from his vlogs.

in Tavern on the Meta on Meta Stack Exchange Chat, 4 mins ago, by Jason C
@Fawad Check out http://data.stackexchange.com/devops/queries?q=tumbleweed for starting points

user228700
Only recently did I find out that the legal age to drink is only 18 over there!

it's 18 in most civilized places

Usually there are two sittings for dinner: an early informal meal that is self service and for which you wear your regular clothes, and a later formal sitting with waiter service.

3:03 PM
or even lower

user228700
@JohnRennie A formal is held every night?!

The formal sitting for dinner happens every night.

@JohnRennie will you help me?

user228700
@0celouvsky Isn't it 21 in the U.S.A?

@Kaumudi.H It is

3:04 PM
The parties with supervisors only happens occasionally.

user228700
@JohnRennie Ohhh, right.

$y(x,t)=a\sin(kx-\omega t +\varphi)$

$y(x,t)=A\sin(kx-\omega t) + B\cos(kx-\omega t)$

Then $a=\sqrt{A^2+B^2 }$ and $\phi=\tan^{-1}\left ( \dfrac BA\right)$ but how?

trig

I hope mathjax is enabled^

3:05 PM
@Kaumudi.H as a general rule the science students weren't too fussed about the sillier traditions, though anything that involved drinking was popular :-)

user228700
@JohnRennie :-) This person (Jake Wright on YouTube) was a CompSci major.

@JohnRennie Do each bond in a liquid molecule get its own degree of freedom?
If you had a linear molecule, X=Y=Z
where XY and YZ bonds could viberate

@Fawad that's just a trigonometric identity. I don't remember how to provide it offhand but it should be easy to Google.

do each type (XY and YZ) vibration have its own degree of freedom?

user228700
3:08 PM
@0celouvsky x'D

@0celouvsky no future mod

3

Express in the form $A\sin(x+c)$ a) $\sin x+\sqrt3\cos x$; b) $\sin x-\cos x$ sol: a) $A=\sqrt{1+3}=2$, $\tan c=\frac{\sqrt 3}1$, $c=\frac\pi3$. So $\sin x+\sqrt3\cos x=2\sin(x+\frac\pi3)$ b) $\sqrt 2\sin(x-\frac\pi4)$ Can someone please explain the method used in the provided sol...

@0celouvsky Given that your answer consisted of the single word trig I felt it was worth expanding on it.

aww

user228700
@0celouvsky Dude -_-

@0celouvsky nope for me, as far I know, I have nobody on ignore

3:09 PM
I said no take backs
too late

user228700
Eh.

@0celouvsky starred what?

user228700
@JohnRennie He said "Do people have me on ignore or just ignore me?"

2 mins ago, by 0celouvsky
whoever starred this will not wake up tomorrow (no take backs)

3:10 PM
aw fail

user228700
I (and someone else) starred that but he edited it to "Whoever starred this won't wake up tomorrow" -_-

@Kaumudi.H people can see history

user228700
Ooh, I didn't know about that feature.

@Kaumudi.H ah :-)

3:12 PM
@JohnRennie and yet it was correct

@Kaumudi.H If you click on the down-arrow at the left (which you can see if you hover over the message), you get a link named "history"

user228700
Right right, I found it, thanks :-)

@0celouvsky help me with specific heats pls

last time you helped me with the SH for solids

user228700
3:13 PM
@JohnR: How to eat corn on the cob whilst preserving dignity?

0celouvsky disappeared.

@Kaumudi.H Impossible :-)

user228700
Exactly.

user228700
It was filling though!

Butter running down your chin is all part of the fun :-)

3:14 PM
wow I have just figured out by scrolling up, I can go to PSE from h bar chatroom

user228700
Last time I ate it was years ago because I couldn't risk damage to my braces during the 3 years I was wearing them.

I had braces too. I used to break them once every 3 days.

@Kaumudi.H Ah.My niece is currently wearing braces, but I don't think she likes corn on the cob, so that's OK :-)

user228700
Hmm, OK :-) Gosh, 3 years is such a terribly long while to be wearing braces.

user228700
3:17 PM
@Yashas You were worse, then :-P I certainly broke them but only about once every 8 months or so.

I didn't get braces because the orthodontist said I didn't need them
Now they're saying I do

Two of my teeth were nearly perpendicular
the doct removed two of my perm teeths
there was no space even after they were removed

user228700
Lol, two? Try four. They removed 4 of my permanant teeth.

aw

are you talking about wisdom teeth?

3:19 PM
was your jaw so small lol?

Most viewed quantum tumbleweed:
0

I am aware of Gibbs measures, given the energy (Hamiltonian) of an arrangement, one can determine the frequency of the arrangement. Plug the energy level in the Boltzman equation and there you go. I also just found out that the variational theorem is used in the Fock Hartree method in order to ...

user228700
@0celouvsky Nope.

wtf is wrong with Indian teeth?

user228700
@Yashas No, my teeth were too large for my mouth.

India is a pretty weird place

3:20 PM
I read on r/india that the internet is terrible

54

I'm a mathematician who recently became very interested in questions related to mathematical physics but somehow, I already have difficulties in penetrating the literature... I'd highly appreciate any help with the following question: My aim is to relate a certain (equivariant) linear sigma mode...

well the internet is terrible everywhere

and that people go to IIT because they want the status, not because they value innovation and technology

I think cows might be able to answer that one

@JohnRennie I know how to do when coefficients of sin and cos are numbers. We multiply and divide by sum of squares of coefficients. And fractions will be angles of sin and cos. Then it becomes in form of sum and difference of angle function . But how to do when coefficients are not numbers? Dividing by sum of squares of coefficients will not give known results of sin and cos.

3:20 PM
@0celouvsky ^^^^ TRUE!!!!!!!!!!!

then again, who does
I hate software engineering

All the top rankers take CS in IIT just becaz they have the rank!

and yet
Here I am
I just need the moné

user228700
Eh, I wish we'd stop saying such things as "India is a pretty weird place". We do have a strange culture but we never seem to shed light on the more fascinating aspects of it.

3:22 PM
11 hours ago, by blue
@Yashas Stop boasting about India now:-P

meanwhile the most highly voted unanswered question in maths that is unanswered in MO has the number of votes I expect: 3 digits
234

I recently read about the Ring Game on MathOverflow, and have been trying to determine winning strategies for each player on various rings. The game has two players and begins with a commutative Noetherian ring $R$. Player one mods out a nonzero non-unit, and gives the resulting ring to player 2,...

@0celouvsky o0 no if you are talking about humans; but animals have the right to use every place as the toilet

user228700
I agree that we're messed up in many many ways but we have also got one of the most dynamic and diverse cultures in the whole world, many aspects of which are completely fascinating and remarkable.

@Secret it is answered on math overflow

user228700
@0celouvsky In slums, perhaps.

3:24 PM

@Fawad the identity is $$a\sin(x+c) = a\cos(c)\sin(x) + a\sin(c)\cos(x)$$ Yes?

the easiest way to find the trig identities is to just use the exponential

@ACuriousMind "Limites und Kolimites" ...is the German word for limit "Limite"???
how does one pronounce that
@JohnRennie Pf. needed.

Short GR question: Are all transformations that map from one reference frame to another in any spacetime must necessary be conformal?

@JohnRennie $$a\sin(x+c) = a\cos(c)\sin(x) +a \sin(c)\cos(x)$$ yes.

3:26 PM
@Secret what?
I don't think so, why would you think tht

So: $$a\sin((kx-\omega t) + \phi) = a\cos(\phi)\sin(kx-\omega t) + a\sin(\phi)\cos(kx-\omega t)$$ Yes?

@0celouvsky 1. The "proper" German word for limit is Grenzwert. 2. We do also have just Limit, which becomes Limiten in the plural. 3. The usage of Limites hints at someone with an education in Latin, since '-es' is the proper Latin ending, but Limites is not a German word.

0

Did the 12-27-2004 gamma ray burst cause any illness affects upon life on earth? Do we know what hemisphere of the earth or portions of the earths surface received the highest radiation? What was the time duration of the radiation as observed on the earth? If one hemisphere was exposed to the maj...

off-topic?

@JohnRennie yes

@0celouvsky Uh, I recall that in order to preserve the constancy of the speed of light in all inertial reference frames, the transformations between reference frames has to be conformal. However for non flat spacetimes, I am not very sure given noninertial frames sort of mess things up and (I forgot) the speed of light between two points in a non flat spacetime cannot be compared because they are in two different tangent spaces?

3:29 PM
@Secret yeah conformal transformations preserve causal structure
@ACuriousMind Ok.

@Fawad So we write $A=a\cos\phi$ and $B=a\sin\phi$ making our expression $$A\sin(kx-\omega t) + B\cos(kx-\omega t)$$

Hi never been to a chat room before! What do you guys do here exactly?

@Fawad So $$A^2 + B^2 = a^2(sin^2\phi + \cos^2\phi) = a^2$$

@Utkarshfutous General chat for Physics Stack Exchange

3:31 PM
the velocity of two distant points have to be parallely propagated along a curve to be compared

Oh! Even I am appearing for JEE this year! Quite nervous about it

@JohnRennie let me do from here , for tan

You'll find that the speed of light is conserved in that case

ffs

@0celouvsky :-) There is no escape!

3:32 PM
Transformations between reference frames are just a change of coordinates

@Secret It is known that every transformation that preserves null geodesics is conformal.
I...think.

It doesn't change the physics at all

(oops sorry, I read too slow and delete too quick...)
0celo and Slereah: Got it

@Utkarshfutous we talk about anything. Sometimes physics, sometimes maths, and sometimes food.

and active transformations are diffeomorphisms, which also preserve all such physics

3:33 PM
Or rather, the null geodesics determine the metric up to an overall factor.
I think that's the precise statement.

Of course on a more naive interpretation things may seem fucked up
For instance with the Born coordinates
Objects do appear to move at $>c$

user228700
I'm off. Goodnight!

I still don't know how Born coordinates work, really

Ah, the latest LHC data is in and reassuringly the Higgs is still there. It would be kind of embarrassing if it had disappeared :-)

I think there's a bunch of patches to do

3:36 PM
@Kaumudi.H Goodnight

@0celouvsky does Gourgoulon cover born coordinates

He does
or at least born transformations

800 pages
Fairly long

Johnrennie: Hmm, so nothing new in those graphs, but nice to see the Higgs finding is replicable

@JohnRennie Do you have any thoughts on last month preparation of almost most important exam

3:47 PM
Einstein's greatest discovery is most certainly the Einstein notation

@Utkarshfutous get a bag of cocaine and a lady of the night
go crazy

Take 30 mock tests :P

Cocaine is a good drug for exams

@ACuriousMind What does "$e_n(x)$ depends functorially on a finite number of jets of the symbol $p(x,\xi)$" mean?

Will make you well focused
one fellow in my class was rumored to be on coke or somesuch during exams

3:50 PM

why are scalar fields noted $\phi$, anyway

$\phi$ld

@JohnRennie you know about it! Yes that's the one

@Kaumudi.H I can't speak for India, but being from Bengal, I do believe we have - during the second half of the 200 year long British colonialism - created international-level art (film/literature), progressed significantly in science, and culturally developed a lot. But it's all in ruins right now.

@Utkarshfutous JEE discussions are to be conducted elsewhere.

3:51 PM
@Utkarshfutous I can't make any useful comment as it's getting on for 40 years since I last did an exam. But what worked for me was just doing lots and lots of past papers.

@Utkarshfutous Which state are you from?

@0celouvsky beeyumbole

@BalarkaSen Beeyumbole.

@Utkarshfutous The thing about exams is that they don't test how good you are at physics, they test how good you are at doing exams!

what the hell is that

3:53 PM
@JohnRennie I don't think that is true for JEE.

@Yashas Gujarat but studying in kota

Those who score 100/100 in Physics in high school exams don't even get 30/360 in JEE Advanced

Well I've never sat the JEE, but this has been true of every exam I've sat.

Oh my goooood

Some school toppers don't even qualify for JEE Advanced lol

3:54 PM
@0celouvsky beeyumbole

@JohnRennie appreciate it. Thanks

@Yashas because everyone don't go for special coachings and study special for that entrance

"We refer to the literature for further details"
Wtf he can't be arsed to give the references?

@Yashas school exams test how good you are at doing school exams. The JEE Advanced tests how good you are at doing the JEE Advanced.

@0celouvsky He did.

3:55 PM
@JohnRennie The syllabus for school exams and JEE Advanced are the same.

@BalarkaSen where

to the literature

@Yashas but the style and content of the questions aren't

did you decide on the second edition?

3:56 PM
@skillpatrol yeah I need to get it

@JohnRennie you should definitely check out the question paper once you will enjoy ii

cool

the section on holomorphic $\psi$do's is unintelligible in the first edition

@JohnRennie there are special coaching centered where they are thought how to solve problems. They are not teached for school exam.

that section is completely rewritten in the second

3:57 PM
@Utkarshfutous I doubt that :-) If I never have to do another exam again it will be too soon :-)

@Utkarshfutous How did you do in Main?

Just fine

300+? 250+? 200+?

@JohnRennie holy crap
the price got raised \$4
did you do something?
or does Amazon track page clicks and then raise prices?

3:59 PM
Eh?

@JohnRennie The price of Gilkey got raised.

@0celouvsky they increase rates when more people visit to buy book?