Recent content by unih

Hi dear all Please explain to a stupid dummy a very simple thing. Take an a photon in 1+3 dimensions. How DOF it has? We all know that 2. How we calculate it? a) 1) We have a spin 1 particle that should have 2s+1=3 spin state. So DOF=3. 2) We have 4 Aμ guys. One is out because of gauge...

Posting to "Advanced Physics Learning Materials" When I try to post new thread in "Homework & Coursework Questions" (and it seems to be the same in all "education") it tells me that I haven't permission to do that. All other threads (for example "high energy") are working fine. Its a bug or a...

Thank you. WIll take a look

Hi dear all If we looking at Cooper pairs as on the particles what is potential between them?

Thank you very much!

Thank you VERY VERY MUCH! I have no words to tell how you helped me

Hi! Please help the idiot In[] = D[p[x,t],x,t]/.{Derivative[n_,m_][p_][q__]->a^(n+m)} Out[] = a2 In[] = D[p[x,t],x,t]/.{Derivative[n__][p_][q__]->a^Plus[n]} Out[] = a WTF? Why not a2? In the simplest case In[] = D[p[x,t],x,t]/.{Derivative[n__][p_][q__]->Plus[n]} Out []=Sequence[1, 1] In[]...

Thank you. I did smth like that The problem is not a subscript (in matematika code I don't use them, here they are just for beaty). the problem is that i want to do smth automatically and up to the order I want.

Thank you for your replay! For example u1(t,x,y)+u1(t,x,y)2+∂xu2(t,x,y)+∂tu1(t,x,y)+∂tu2(t,x,y)+u1(t,x,y)∂tu2(x,y,z)+∂tf(t,x,y) now I take into account that u1~u1~∂x~∂y~ε , ∂t~ε2 and alculate the orders of every part of expression u1(t,x,y)~ε u1(t,x,y)2~ε2 (=1+1) ∂xu2(t,x,y)~ε2 (=1+1)...

I know what is Series. They don't do what i need

Hi dear all I have some functional in Mathematica that depends on the functions (for example u1(x,y,t) u2(x,y,t) and others) and its derivatives. I want to expand this functional in series of ε. Its perturbation theory as you understand, and I should take into account that not only functions but...

Thats smthh with the same idea arXiv:gr-qc/9904054v2

Thank you veryu much for your answer Yes, I saw review by Cook, and still doesn't understand it. Lets take for example the classical article of Shapiro and co http://prd.aps.org/abstract/PRD/v38/i10/p2972_1 They are looking for apperent horizon, that they define as a marginal surface...

Thank you veryu much for your answer Yes, I saw review by Cook, and still doesn't understand it. Lets take for example the classical article of Shapiro and co http://prd.aps.org/abstract/PRD/v38/i10/p2972_1 They are looking for apperent horizon, that they define as a marginal surface witha...

HI all There is smth I don't understand in building initial data for BH The equations everybody uses uses spacetime or timelike hypersurfaces but for example horizon is a null surface!