The h Bar

12:24 AM

Reading ACM's and AFT's QFT tagged answers is basically just as useful as reading a book when learning QFT if not more useful. (definitely more fun)

peterh

12:35 AM

@bolbteppa My algorithm is that I learn into the direction for what I want, and if I find one, then check also the math needed for it.

Secret

link.springer.com/article/10.1007/s10948-017-4302-3

Now I have read this paper in full: Basically, the phase induced in the electronic wavefunction as it interacts with electromagnetic fields in a semi classical manner is the source of the induced emf, thus explaining why the faraday's law and Lorentz force law give the same emf value. In addition, the phase factor that is imposed to ensure a single valued wavefunction in conventional superconductors result in the persistent current,Josephson effect and Messiner effect as the phase arises from a

topological effect in the superconductor

vzn

1:50 AM

@Secret solitons, YAY! =D

Secret

2:46 AM

It is nice to see how the phase induced by gauge freedom finally have some sort of physical interpretation, even though not really a direct one. If this result is still reasonably valid up to the QFT level, then the wavefunction may have more physical impact than we thought of.

of course, the result is still consistent with SR. Ultimately, it is Lorentz transformation that give rise to that gauge freedom in the first place

For those interested, let me know if I have misinterpreted this paper

Secret

1

Q: In Feynman functional integrals why do we integrate the action over all time?

Say the definition of a propagator in quantum field theory is: $$G_F(x,y)=\int \phi(x)\phi(y) e^{i S[\phi] } D\phi$$ where S is the action. Why do we integrate the Lagrangian from $t=-\infty$ to $t=+\infty$ instead of from $x_0$ to $y_0$? i.e. $$S[\phi] = \int\limits_{-\infty}^{+\infty} \int\...

Nonlocality is fun

Anonymous

3:33 AM

@PrathyushPoduval I meant that the M-B distribution function is given later on in the book (along with the derivation). Even before they stated the M-B distribution, they used it to derive the average $E$.

Anonymous

Moreover, $<E>$ doesn't evaluate to $\pi k T$: hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/molke.html#c2

Prathyush Poduval

4:30 AM

@Blue yeah,you’re right it doesn’t.....in the context the factor doesn’t matter but since it has its own name, it could be something interesting

@Blue usually it’s done the other way around :P, which book are you using?

vzn

4:43 AM

@Secret wavefn is REAL™ =D

Anonymous

@PrathyushPoduval This. It does have some topics which Reif misses out.

Prathyush Poduval

4:56 AM

@Blue how is it?

Koolman

@dmckee I was learning from codesdope.com/c-introduction

And I have learn till string topic

Should I restart from that book ?

@JohnRennie What are your thoughts ?

Practice : codesdope.com/practice/practice_c

John Rennie

Have a read through the first couple of chapters of K&R and see if you like the style.

dmckee

^ Best advice.

John Rennie

You may decide you don't like it, in which case stick to the web site.

dmckee

Can't say I care for the pep-rally style of the link you provided, but that won't prevent it from being a good guide to the language if it settles down.

John Rennie

5:06 AM

Learning a language should be fun. I found it absolutely fascinating and worked through all the problems because they were such fun to do. If you don't find working through K&R enjoyable then don't use it.

dmckee

You have to be using a pretty contrived definition of 'powerful' to honestly consider c the 'most powerful language'. Its structures map nicely onto a 1970s CPU, and onto the conceptual model of computation that is still widely used, but it lacks a good deal of built-in expressiveness found in other languages.

I still use it for some things, but given that I already know it pretty well it is a good choice for those things. But I use other languages, too, and mostly because they are faster to code in.

John Rennie

Though many of us retain a lot of affection for the old hoss :-)

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