Re: [Maxima-discuss] energy-momentum tensor

[Viktor T. T. <vt...@vt...>]

Dear Dimiter,

No, I do not. The canonical energy-momentum depends on whatever fields we are dealing with. I am assuming that you have in mind the electromagnetic field and its energy-momentum tensor? In itensor, it would be something like

load(itensor);
imetric(g);
igeowedge_flag:true;
components(F([i,j]),extdiff(A([i],[]),j));
components(F([i,-k],[]), g([-j,-k])*F([i,j]));
components(F([-l,-k],[]),g([-i,-l])*F([i,-k]));
components(T([-m,-n]),F([-m,-a])*F([-n,a])-1/4*g([-m,-n])*F([a,b])*F([-a,-b]));
ishow(T([-m,-n]))$

(Note the use of the negative sign for contravariant indices; this notation was implemented specifically to ensure that index ordering is preserved when indices are raised/lowered, as in this case.)


Viktor





> -----Original Message-----
> From: Dimiter Prodanov [mailto:dim...@gm...]
> Sent: Friday, January 6, 2017 11:45 AM
> To: max...@li...
> Subject: [Maxima-discuss] energy-momentum tensor
> 
> Dear Viktor,
> 
> do you have code for compuation of the canonical energy-momentum tensor?
> I would like to implement it in clifford so I want to compare it with reference implementation.
> 
> best regards,
> 
> Dimiter