(idea) by 90% fat free Fri Mar 23 2001 at 12:58:11

In Electrodynamics, this tensor is defined in terms of the Maxwell Tensor as follows:

    Tμν = (1/μ0)(FμρFνρ-(1/4)ημνFρσFρσ)
For a fluid with pressure p and density ρ,
    Tμν = (ρ+p)uμuν + pgμν

Together these act as the source for the gravitational field in General Relativity.

I like it!