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user54412
12:15 AM
@ManishEarth Looking for a challenge, eh?
 
user54412
I'm actually spending the next week visiting a collaborator to hash out GR in new and crazy ways
 
What does new and crazy mean?
 
user54412
or, to the extent that what we're doing is not new, it's the sort of technical thing no one ever bothers publishing, so off we go to rederive it once again
 
@ChrisWhite yeah :)
 
user54412
@tpg2114 adding MHD :P
 
user54412
12:20 AM
which to be fair has been done by a lot of people, but everyone's published methods are very situtational and not generalizable to other cases
 
I don't know enough about GR, or MHD, to know how either one changes the other
 
I sorta did some GR on my own a couple of years ago, so what looks trivial to me isn't always trivial to everyone else. So.... I expect a bit more from the course (I know that it will speed up soon though)
MHD = hydrodynamics?
 
magneto-HD
 
ah
I actually drew a Christoffel symbol in matrix form (drew it as a matrix of vectors, and tried but failed to draw it as a 3D matrix) because I got bored
 
All I know about MHD is that it can stabilize fluid instability like the RMI problem or turbulence... but that's the extent of what I know
 
user54412
12:22 AM
@tpg2114 Neither do I :P
 
There's a poster about that from our lab outside my boss's office... so I've read it many times while waiting
 
user54412
The equations of ideal MHD (in covariant form): $\nabla_\mu J^\mu = \nabla_\mu T^{\mu\nu} = \nabla_\mu {}^*F^{\mu\nu} = 0$
 
user54412
written like that, they don't seem all that bad
 
Navier-Stokes written as F = ma don't look so bad either :)
 
@tpg2114 lol
@ChrisWhite Why do we specify "MHD equations in covariant form" or "EM equations in covariant form"? Is there a contravariant form? And if so, what's the difference -- it would be just a transformation away, right?
 
user54412
12:33 AM
@ManishEarth sometimes "covariant" means "opposite of coordinate-dependent" rather than "opposite of contravariant"
 
user54412
sure, you can raise and lower indices to your heart's content
 
@ChrisWhite ah, I see.
 
user54412
(or at least that's my usage of the word)
 
1:00 AM
"Hello world"
(my programming side coming out there...)
 
user54412
printf("Hello @Terry Bollinger\n");
 
tempted to do the same in brainf*ck but I will resist
 
:)
Great googly mooglies, is that the name of some real programming language?
Hi Chris. It always amuses me that the C family of languages stole the printf formatting from ancient Fortran. And that Fortran and Lisp were the first...
 
user54412
there is no higher compliment than imitation :)
 
user54412
(and that's about the only compliment I have for Fortran - sorry @Kyle Kanos ;-)
 
user54412
1:13 AM
@TerryBollinger not only is it real, it's currently featured on the esoteric programming languages wiki
 
Chris, so I see, I just looked it up on Wikipedia! That is a delightful syntax, and at least an order of magnitude more meaningful than string theory (hey, this is a physics chat, I had to say something physics-ish...)
 
user54412
wow, there are hundreds of them cataloged, and that's excluding things they deem "jokes"
 
user54412
@TerryBollinger It is rather Turing-machine like
 
That list says something very scary about programming and programmers I fear...
David Z, how's the snow situation up there? We're getting good melting here a bit farther south, glad to see it go.
 
user54412
btw @Terry since I remember you being associated with language and such, you might find ~English interesting
 
1:29 AM
@Chris, that is interesting... Dr Nicholas Cassimatis, creator of Polyscheme and now working at Yahoo, has created some of the best low-processing-overhead English comprehending software I've seen.
My son just showed me LOLCODE and I could not stop laughing.
Later, my wife just arrived also...
 
1:59 AM
@tpg2114: Way to try settling a dispute :D
And I'm also saddened by the loss of 140 points from my Schrodinger equation post.
 
1
Q: Should this question be on hold?

David ZWhich component shows spin squeezing under twisting Hamiltonian? There is a contentious debate emerging about whether this question, currently at revision 5, should be open or not. Standard practice is to bring the discussion to meta, so here we are to discuss: is it right for revision 5 to be o...

 
 
2 hours later…
3:47 AM
@KyleKanos I never professed to be looking out for anybody but myself ;)
@DavidZ Regarding that question, can we nuke/move the comments elsewhere? They really don't belong there...
@KyleKanos Easy come, easy go. I'm gonna lose 200 on a bounty. So long as you don't drop below important privilege boundaries, it's all good
 
4:47 AM
@tpg2114 Yeah, I'll get rid of them once the issue is resolved, but I'm leaving them in place for the moment because it's an active discussion and people may want to refer to the comments for the meta post.
 
gow
ow
what is physics?
 
@TerryBollinger lots has melted over the past two days or so, but we had a lot of snow built up from the previous couple weeks so there's still plenty on the ground
 
@DavidZ how do my avatar looks?
 
Fine, I guess... why?
 
@DavidZ how do you feel after watching my avatar
 
4:50 AM
I really don't know what you're getting at
 
 
6 hours later…
11:12 AM
Why is the square of a quantum field infinite?
 
 
1 hour later…
12:30 PM
Hello
 
12:48 PM
Hi
 
Hello
Can someone help me with a statistical mechanics question ?
 
 
1 hour later…
2:01 PM
@tpg2114 That question goes right to the problematic heart of the current policy. There is an in principle difference between doing the physics and doing the computation, but in practice some problems are solving almost entirely by people from the discipline that throws them up.
 
2:56 PM
0
Q: Why you must login to ask a question in physics.stackexchange.com?

ErrorWhy you must login to ask a question in http://physics.stackexchange.com while other sites are free and open to everyone? Link: How does it work ...you can ask or answer questions without even bothering of register... Why Phys.SE is out of scope of Stackexchange!?

 
3:48 PM
Any comments about this video.......
 
4:07 PM
@Arafat Watched 10 seconds and seems BS.
He just gives philosophical arguments.
 
4:32 PM
0
Q: How can i make my question On topic?

AnupamI asked this question Effects of microwaves a few days ago. I really asked some offtopic things but now i've edited it appropriately. But it is still closed. So how should edit this to make it on topic?

 
 
2 hours later…
6:50 PM
How I hate people who don't seem to know what capital letters are.
 
what's a capital letter :p
What bothers me is erroneous punctuation (e.g., i did this .then i did that .then i got this .)
 
7:10 PM
@KyleKanos uh, could you avoid comments like the downvote-bet one? Not really constructive, and it sours the discussion :/
 
@ManishEarth I suppose I can do that.
 
Thanks :)
 
@KyleKanos What is the correct punctuation (if any) after 1) 'e.g.' and 2) 'i.e.'?
 
Mark davenport stated UFO May not be space travelers but time travelers. What is the relation to how it would many lifetimes of space travel at 50 percent the speed of light to go in the future and how these UFO era can I stantely go into the future without traveling(
 
7:13 PM
@GlenTheUdderboat no capitals
 
Does shooting through space magicall make u go to the future but we don't have he speed to do it. Does it have to do with where to go in space that makes u go to he future if so
 
@GlenTheUdderboat Some of SE's experts say that e.g. should be followed by a comma while i.e. should not
 
@KyleKanos Nice, that's my opinion as well.
 
But my point was actually about the periods I used. I've seen several people use the word space period|next notation, rather than the standard word|period space next
@ChrisOkyen The question doesn't make any sense.
 
Printf("hello H Bar)
 
7:18 PM
@KyleKanos It's actually one of the very few instances where Latin class obviously helped.
 
@GlenTheUdderboat See, I'm of the opinion that i.e. should be followed by the comma
 
@KyleKanos Well .You are wrong .If you'd know Latin, you'd know this too .
 
KyleKanos I was wondering if where you move really fast in the universe changes how far in the future u go
 
i.e. means that is. In English, you'd say, "That happened two months ago, that is, December." which could be written as "That happened two months ago, i.e., December."
@GlenTheUdderboat I took 4 years in high school (but graduated there in 2001)
@ChrisOkyen Yes:
In the theory of relativity, time dilation is an actual difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses. An accurate clock at rest with respect to one observer may be measured to tick at a different rate when compared to a second observer's own equally accurate clocks. This effect arises neither from technical aspects of the clocks nor from the fact that signals need time to propagate, but from the nature of spacetime itself. Overview Clocks on the space shuttle run slightly slo...
 
@KyleKanos "That happened two months ago, that is, December." isn't English.
 
7:21 PM
@GlenTheUdderboat Well if you add "in" before December it'd be English
 
@KyleKanos Still not. Closer though.
 
But whether u move 50 percent of the sol towards Pluto or towards the Draconian constiLation does it change anything?
 
@ChrisOkyen Speed is the only thing that matters, so the answer is no.
 
@GlenTheUdderboat Looks good enough to me, what is it that you're expecting?
 
7:30 PM
What way theoretically would they warp to our time without moving through space or anything that wouldn't be tehnogy like a simgarity. Whether times linear in multi-versed slash par or as the string theory goes as the new world order shill Michael kaka ( Russian for poop as is his stance)
 
@KyleKanos "That happened two months ago. In December[,] that is." Not too sure about this. :)
 
@ChrisOkyen Uhh...what? Time travel works one way: ever to the future. Backwards time traveling is a romantic dream of science fiction.
@GlenTheUdderboat I think it works both ways.
 
Ok so how would era go to the future other than going close to the sol or just fast or slowing Down time
 
@ChrisOkyen I have no clue what you're saying here.
 
Assume eye are time traveler right? How would they go to the future without the way of going really fast?
 
7:37 PM
You're going into the future as we speak, yet you are not traveling very fast, are you?
 
But how could one perpetuate it so they go so they warp to the same area they as in he fries and keeping skipping like thy they get to their destination way in the future
Would that concept be linear time or parralel universes btw
 
There's no such thing
 
7:56 PM
@KyleKanos "There's no such thing" as what?
 
@GlenTheUdderboat There's no such device that lets you skip over time into the future.
 
 
2 hours later…
9:58 PM
@KyleKanos Yet. Give me some more time.
 
Haha, what is a fluid dynamicist going to do about time travel?
 
You underestimate my evil genius capabilities...
 
Okay, I'll try to not do that
 
Academia may just push me over the edge to use my powers for evil rather than good!
 
I made a new Latex command: \pde[2]{\ensuremath{\frac{\partial #1}{\partial #2}}}. I then used \pde{^2f}{x^2} and got the diffusion equation I wanted :D
 
10:03 PM
I always make cool latex commands like that
Then forget to actually use them
 
@KyleKanos been there, done that
 
And have a crapload of \frac{\partial}{\partial} all over
 
@tpg2114 I'll probably do that
 
I actually got outside to enjoy the sun today. That's a foreign concept lately
 
I've been cramped inside
Arguing with the idiots over at SciComp
 
10:06 PM
You didn't just use PETSc?
 
17
Q: Are there simple ways to numerically solve the time-dependent Schödinger equation?

episantyI would like to run some simple simulations of scattering of wavepackets off of simple potentials in one dimension. Are there simple ways to numerically solve the one-dimensional TDSE for a single particle? I know that, in general, trying to use naïve approaches to integrate partial differential...

You guys merging it
Almost as soon as it was down, I got 3 downvotes
The a-holes disagreed with my loose equivocation of the Schrodinger equation with the Reaction-Diffusion equation
So they downvoted it
I argued, It's in the fucking literature and the main a-hole still won't accept that he's entirely wrong
 
You didn't mention PETSc or Trillinos in your answer at all. That borders on "not an answer" over there!
 
Read the comments :D
Or at least my first one after the David Kasshole comment with the +4 (voted-up by idiots)
 
Hah, nice
I'm sure that whole thread will get nuked soon
 
Probably
Which is why I was quick to show you
 
10:12 PM
Screenshot it for posterity
You should hang onto it
 
Done
 
@KyleKanos /@tpg2114 Use physymb, it has \ud,\udd,\uddd, and \pd,\pdd,\pddd. Written by DavidZ
 
AIAA also includes things like that in their journal paper template
 
Does anyone here know about vector spherical wave functions, M_mn and N_mn? (not M_{emn} or M_{omn} or N_{emn} or N_{omn})
@ManishEarth I'v upvoted that question (time-dependent SE) and Kyle Kanos's answer when it was here on physics.SE , yet I can upvote it again on ComSci!!
 
eh, that's a known thing
minor issue
 

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