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...
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)...
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...
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!