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7:12 AM
Hi, ManishEart.
 
 
3 hours later…
10:06 AM
@DavidZaslavsky Does look like a meta tag to you?
 
Man of Steel : June 13, 2013
 
 
4 hours later…
2:25 PM
What's a symmetry arguments/
?
 
2:39 PM
@Brooks ?
Context?
Usually when you invoke symmetry to simplify a situation
"The situation is symmetric in the x direction, so v_x should be 0"
et cetera
(Or are you talking about invoking Noether's theorem?)
 
3:11 PM
@ManishEarth, thanks. Here is my question. physics.stackexchange.com/questions/67033/… You should pay attention to the comment made by fffred.
 
user54412
3:48 PM
I just reviewed 22 close votes, and a full 15 of them were on decent to very good questions
 
user54412
Are we aiming to become even more elitist than english.SE???
 
@ChrisWhite Hm. The mods have been taking a vacation from closing stuff (to see if the community can be prompted to start doing it), but if you want I'll have a look and punt them out of the queues
 
user54412
Welcome to Physics Stackexchange. We answer conceptual questions about string theory. If your question has an answer not involving algebraic geometry, it is not welcome. Astronomy, fluid dynamics, material properties, and experimental techniques are also not welcome.
 
Yeah, that's what really want to avoid
I personally have nothing against the basic community on the site
HW questions - yes, but other than that not really
 
user54412
@ManishEarth I have a theory that most regular users have an infinitesimal window of acceptability
 
user54412
3:54 PM
People aren't interested in things they don't understand
 
user54412
At the same time, anything they do understand well they consider below them and not worth pausing to explain
 
Exactly
Just because person A thinks that topics B,C,D are useless doesn't mean that they really are
@ChrisWhite You probably have heard of this one, but:
 
user54412
@ManishEarth Actually I hadn't seen that
 
user54412
interesting
 
user54412
Hmmm - I'm 1 vote short of being the most voting member this year
 
user54412
Time to vote on more questions....
 
@ChrisWhite upvoteallthequestions.jpg
 
4:23 PM
@ManishEart, I have give you the context of symmetry arguments.
 
hm? bit busy
You mean this comment?
I do not agree with the statement that the heat flux has to be normal to the isothermal surface because it would create a transverse gradient otherwise. For example, one could imagine that the vector is not normal to the surface because it did not have time to generate the transverse gradient. The true explanation, in my opinion is a symmetry reason: imagine an infinite isothermal plane. The heat flux has to be normal to it because all contributions will be statistically distributed symmetrically. — fffred 10 hours ago
oic
 
Yes.
 
fffred has it exactly right, you can only get to the orthogonality condition through symmetry arguments. It's not true, for example, in the case of a material with a highly anisotropic thermal diffusivity. I don't know if such materials exist, but they're certainly not ruled out by thermodynamics. — Nathaniel 8 hours ago
They're basically saying that when the material is anisotropic, the flux will be normal due to symmetry
Because if it wasn't
Then there would be a "preferred direction" to the material
And that's not allowed by the symmetry of anisotropy
 
How about normal conductor?
 
?
What you mean by that?
Normal as in non-exotic?
Usually conductors are sort of isotropic.
 
4:27 PM
Normal is isotropy.
 
Hm
Well, technically metals are crystalline, so yeah
In that case there still isn't a preferred direction so you would have orthogonality
 
But I don't know how the direction of heat flux come from.
Am I express my question in that site clearly?
 
not sure
again, bit busy
 
 
2 hours later…
user54412
6:51 PM
3
Q: Why the heat flux vector at a point must be perpendicular to the temperature isothermal surface? 这个垂直性是定义还是推出来的?

BrooksBefore the question: I am working on numerical calculation of three dimension parabolic equation that based on Fourier's Law of which I am a little confused. Here comes the law in modern mathematics language. "The local heat flux is proportional to temperature gradient" $$ \vec{q}=-k\n...

 
user54412
^ so the newly-added Chinese does indeed parallel the English, but why the OP thought adding Chinese would help, I have no idea
 
On the one had I want you to know that the question is contain Chinese. On the other hand, If I wrote it all down it would more than ??? characters.
Maybe it is useness.
uselessness
 
user54412
7:09 PM
@Brooks It's just that only a small number of users here read Chinese, so it probably won't add much for them
 
user54412
I don't think there's anything wrong - it's just unusual
 
8:54 PM
Yes. Thanks.
 
9:11 PM
@ChrisWhite Actually it is wrong - Stack Exchange sites are in English (except for those specifically designed to be in another language).
 
 
2 hours later…
11:16 PM
Darn, where in the world do all these people come from?! At present, the flood of popular, basic one sentence, and bad homowork questions rises again :-/... There is no point in posting anything technical or generally non-basic questions at present, since they would just be flooded down with a rate of 6 very basic posts of laypeople / hour and just disappear unnoticed down the river.
Maybe this is the revenge or attack of Quora ...?
I still suspect that it is not only correlated in time but even related to the change in the frontpage, which gives to not logged in visitors the impression we do mostly popular science and homework help.
And indeed this seems to be what is being done here now and in the future. Physics SE becomes more and more indistinguishable from Quora.
 
A reminder to everyone who has permissions: check the review queues! This is how we get up to five community close votes on questions. physics.stackexchange.com/review
 

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