3+1 decomposition of spacetime
= 3+1 decomposition of spacetime
= 3+1 decomposition
{synonym}
A 3+1 decomposition writes $ds^2=-\alpha^2dt^2+\gamma_{ij}(dx^i+\beta^idt)(dx^j+\beta^jdt)$ in terms of lapse, shift, and spatial metric.
A spacetime foliation separates a spatial metric, lapse and shift. The <ADM formalism> uses this decomposition to express Einstein evolution and constraint equations in Hamiltonian form.