Comment Re:Source term for Einstein's field equation (Score 1) 47
There is no mass term in the stress-energy tensor
There most certainly is. Density-- mass per unit volume-- is the (0,0) term of the stress-energy tensor.
Energy density, yes.
Which is also mass density. Multiply by c to keep the units straight. (If you're a physicist, you just set c=1, and the units don't matter.)
I guarantee, if you have a mass density of M kg/m3 and you put it in Einstein's field equations, you get gravitation.