Recent content by klabautermann

Thanks for the tip, I'm certainly going to look into it!

Good evening, first of all, thanks for your reply and the references. Actually I need to understand this https://arxiv.org/abs/1712.03282 . Since I had virtually no exposure to hydrodynamics so far, I am trying to get a general picture about the subject, so I am working through this...

Hi everyone, I'm interested in relativistic anisotropic hydrodynamics and often a "gradient Expansion" is mentioned in articles, but not how this works exactly. I gathered that this is some kind of expansion of the energy-momentum tensor. Can someone explain to me how this expansion is set up...

I am perfectly aware of what the word 'arbitrary' means und what a normalization constant is. Anyway, thanks for your time.

Thank you for your reply. But why can you assume that by mutliplying the restframe spinor by \frac{1}{\sqrt{2m(E+m)}} gives you a spinor w(p) with arbitrary p?

Hello! I have a question regarding the construction of solutions to the Diracequation for generell \vec{p} . In my lecturenotes (and also in Itzykson/Zuber) it is stated that it is easier than boosting the restframe-solutions, to construct them by using...

hi! i came across this thread by discussing a similar problem in the forum. i thougt they convinced me that gauss's law is valid in this problem, but it bugged me the rest of the day, so i continoued to think about it. i would appreciate it if you could take look...

nicly done, very good argument! i am convinced, thank you for the insight gabbagabbahey! thanks to all of you for the discussion and excuse my stubbornness!

my point exactly. the field extends to infinity and i want the field due to all charges. I've painted a picture, maybe this helps to clarify this. i have the feeling i am beeing missunderstood. (of course the distribution is continous, etc...) yes, that's right!

for example let's say you have this charge distribution ρ=ρ_{0}e^{-kr} this time not all over space but for r<= a and a singel point charge q at x=a+c where c>0. now if you use gauss's law for the spherical charge distribution, this does not mean you can forget about the point charge, does it?

i am perfectly aware of what gauss's law is, about that it is applicable to mass distributions as well as charge distributions. but this is not a cahrged spherical shell it is a charge distribution over all of space. if i have two charges and exclude one from the surface, this does not mean...

ok, if i take r=a then i account for all the charge inside the sphere with radius a. you are saying, that the charge outside the sphere doesn't contibute to the field at a? (of course it doesn't if i use guass's law because the net flux throu the sphere of charge outside the sphere is zero). yes...

good morning! thanks for your answers everbody! gabbagabbahey: you are right of course, r=z, and of course there is a 2∏ missing. and the last thing you wrote, i meant (r-r')cosθ', thanks! i droped the unit vector, because there is only a field in z direction, i should have given E a...

haha! sorry can't hide my atheism :) about using gauss's law: since the charge distribution is not conifned to a specific region of space, this would not be a good idea since i would not include the chargedensity outside the sphere ...or am i missing something? (also i would like to practice...

good evening! i am trying to calculate the electric field of a spherical charge distribution ρ=ρ_{0}e^{-kr}, where r is the radial distance. i am a little bit embarressed,but i have to say that i am not comfortable with spherical coordinates in practical calculations. i would appreciate if...