MAIN SECTION : The Lagrangian
Let express the equations of motion and the Euler-Lagrange equations with zero right hand sides
\begin{equation}
\bbox[#FFFF88,12px]{\ddot{Q}_{k}+\omega^{2}_{k}Q_{k}-2\dfrac{\dot{q}}{q}\sum_{j}g_{kj}\dot{Q}_{j}-\dfrac{\ddot{q}q-\dot{q}^{2}}{q^{2}}\sum_{j}g_{kj}Q...
I am just hunting for the book THE PHYSICS OF CORRELATED ELECTRONS by Hiroyuki Shiba. See here. I want to buy an English version of it. So where can I buy it?
@JohnDuffield thx for sharing that cool article. it appears that a single experiment that closes all loopholes simultaneously has never been constructed and experiments to close 1 or more at a time are extremely delicate. wondering, is nature telling us something?
I've seen a machinist tell a grad student that he's get right on that after the long weekend, when the same machinist had stayed late to help me out once.
Keeping on the good side of the support staff is useful.
Where I'm at now the informal duties are modest in scope and spread around pretty widely so I benefit from them in proportion to the hoops I have to jump. I am content.
Some places have been a little better others not quite so good.
That's one I would have been happy to say yes to unless there was a pressing conflict. (After all you can't been down at the Pizza place at the same time as you are proctoring an exam.)
I did know one student who didn't want to have coffee duty because of a bad workplace experience.
I gladly picked up sandwiches for our weekly lunch talks. That way someone else could worry about getting the guest settled in and setting up the projector. Never met a projector I could call a friend.
user54412
1:47 AM
@dmckee Morning coffee is so important in my department grad students aren't trusted with it. You have to have a PhD to operate the machines.
As mentioned by someone on the Academia thread, driving a visitor to the airport not only counted for beanie point but was a chance to network like crazy.
@ChrisWhite This was on site at the accelerator where the only people around often enough to know how to work it were grad students and post docs.
And we did have an informal Coffee Working Group that prepared internal documents on the best practices of coffee making.
"Strong coffee can be thinned, but weak coffee is irrecoverable" and the like.
@ACuriousMind Ha! At some point the Europeans in my department convinced the newcomers from Asia that espresso was regular coffee, and anything thinner was defective.
My suggestion is that we find an undergrad classics major and hire them as a barista for certain hours of the day. Fancy coffee shop quality, and it would still be 1/10 the price I bet.
@FenderLesPaul Serious? High energy physics has a lot of dogma? I never knew that......
@NeuroFuzzy you mean how he figured out newton mechanics is not testable? I have no idea, but physicists have kept inputting energy to electrons, and got results exactly contradicting newton mechanics. He probably referred to his modernism crap.
@FenderLesPaul would you mind tell me what exactly those dogmas are?
@0celo7 You'll find that most people who work with QM all the time (as opposed to those who work on QM) subscribe to the "shut up and calculate" interpretation all week even if they noodle around with other ones on the weekends.
A recent issue of NewScientist brought me back to here: http://www.independent.com/news/2013/apr/17/time-reborn/ which lead me to here https://en.wikipedia.org/wiki/Shape_dynamics which lead me to here http://inspirehep.net/search?ln=en&ln=en&p=find+a+smolin%2C+lee&of=hb&action_search=Search&sf=&so=d&rm=&rg=25&sc=0
I don't have the prerequiste to discuss this yet (as mentioned by Sleerach, Ocelo7 and Acuriousmind, I still have a lot of reading in GR to catch up)
however I am depositing this as a seed and see what discussion can come up that I might be ale to contribute or f…
Lee Smolin and other people who worked on shape dynamics (if I understand the very breif outline in wikipedia correctly) seemed to be similar to something I have been working on as a personal hobby for 3 years
Back in my GR course, I read this set of lecture notes, however I already forgot what a pullback is, so much for GR to me!
memory failure
Indeed, after this chem honours, I have heaps needed to catcch up in GR if I want to continue my investigation on nature of time
"Why do people insist on drawing multilinear maps" I am actually one of those people (because I am a visual person on steroids), except I have not showed it yet
I have an arrow like pics for matrix that so far seemed promising in deriving most of linear algebra results from, and checked by my friends and some professors (though they cautions about visualising such things). However a lot of things still remained to be ironed out in particular, it has issues computing eigenvalues and eigenvectors from it
The above is how I tend to see a tensor mathematically. I still remember I am completely confused back in my GR on not understanding what's happening until I read soem maths lecture that shows a tensor this way with its basis.
It is only then I realise tensor equations in physics are often written in terms of their components, and the basis elements are omitted
typo: The last beta_m is superscript
and duplicated \otimes by accident
@Slereah Do the basis ever played a role in tensor equations in GR? is this the reason why they are left out in the calculation?
@vzn : yes, she was, but like Joy Christian, people called her a crackpot. I don't like to hear that kind of thing. Particularly from people who effectively say quantum physics surpasseth all human understanding.
So on the note of maths, over the last 30 days I get about 1 or 2 downvotes a day (for the first 2 weeks, every day, after that they sort of forgot, until today, right after I showed up in chat) - I've got 28 without comment
@Alec Teal I think your answer is well informed on the possible cases of the pulsar question. However, IMO if after the limit discussion you refer back to the differential equation on how it applies, then it will be a perfect answer
I left that out on purpose @Secret because I think the pulsar was only an example, and I used a general function
On math.se quite often you get partial answers, or hints, or showing the lines and such. A lot of my downvotes are things that should have remained on zero. So now they're stuck at -1 forever :/
makes sense, I sometimes solve problems this way to give a global view
One thing I found hard in doing physics problems is using the correct assumption
I have 3 closed questions and 3 downvotes in a row 3 weeks ago that put me on the warning banner
in physics stack exchange
so you are not alone
But that's because I asked too many questions on trying to explain something to a layman with as little loss from rigor as possible (c.f. Higgs boson analogy as refraction of light)
It is one reason my question asking frequency has stalled on physics stack exchange, because I need to tihkn very hard on a question that won't downvote me further to troble
this reminds me of $\langle\psi|H|\psi\rangle$ and an analoguous formula in linear algebra where you multiply a matrix with a basis vector to extract it's column vector component
about tensors, I also have another curiosity. What limits us to only two type of indices (contravarient and covariant)? Is it related to the notion of tensor contraction, thus only two types are sufficient?
I know upper indices transform as the inverse of the linear transformation (i.e. transform like a vector) and lower indices transform as the linear transformation (i.e. transform like a one form). But I am also aware of something called tensor densities (e.g. the levi citiva symbol) which transform as the +-det times the transformation rule for the underlying tensor looking thing as sai…
Too bad my physics major structure have fill in the slots thus I cannot do differential geometry, thus my understanding on that is only fragmented...
I tend to self learn some of the exterior algebra stuff in my free time form wikipedia and some mathematics lecture notes I found on the internet, and as far I know, my understanding is half baked, for example:
I once asked my multivariable calculus professor ( who has some knowledge on exterior algebra
on whether it is sensible to define something that has properties of both a scalar and vector (as if putting two differen vector spaces together), he then said it migth not make sense
because
say if such thing is possible, then how would you handle the issue that division is defined on scalrs but undefined on vectors when you multiply two of these things together
For the final picture, it can be think of as stitching a bunch of vectors pointing in the x direction together along the y direction, but I don't know any sensible way to defined it mathematically or whether it will be useful.
My initial guess is I might be able to use the tensor product, which some sources said it is basically cartesian product restricted such that it obeys linearity, but cartesian product of scalars and vectors is just scalar multiplication, thus this approach does not work
@Slereah I think that's called deWitt condensed notation
@0celo7 Well, there is the notation of division algebra. Only $\mathbb{R},\mathbb{C}$ and $\mathbb{H}$ exist over $\mathbb{R}$ (as finite-dimensional algebras)
I don't even know if such things (not the divison algebra above) are already there somewhere inthe math literaute because if it is, I don't know the term
@Secret This doesn't make any sense. The tensor product is not a restriction of a Cartesian product (it is larger than the Cartesian product!), and the Cartesian product of a space of scalars and a space of vectors is not scalar multipliciation (it's a vector space of one dimension more). It seems to me you should draw less pictures and focus on getting the terminology and formalism right, else no one knows what you are talking about.
@ACuriousMind " It seems to me you should draw less pictures and focus on getting the terminology and formalism right, else no one knows what you are talking about."
OMG, it seems my usual way to handle tensor product back in my GR course is all wrong then (although for some reason my calculations still work when I did my assignments for unkwnoen reason (my misunderstanding will be shown later in latex))
MAIN SECTION : The Lagrangian
Let express the equations of motion and the Euler-Lagrange equations with zero right hand sides
\begin{equation}
\bbox[#FFFF88,12px]{\ddot{Q}_{k}+\omega^{2}_{k}Q_{k}-2\dfrac{\dot{q}}{q}\sum_{j}g_{kj}\dot{Q}_{j}-\dfrac{\ddot{q}q-\dot{q}^{2}}{q^{2}}\sum_{j}g_{kj}Q...
I am just hunting for the book THE PHYSICS OF CORRELATED ELECTRONS by Hiroyuki Shiba. See here. I want to buy an English version of it. So where can I buy it?
