Poisson 1813: u(x) = (1/(4pi)) integral rho(y)/|x-y| dy gives potential from mass-distribution; -Delta u = rho; basis of gravitational + electrostatic potential theory.
Poisson 1813: u(x) = (1/(4pi)) integral rho(y)/|x-y| dy gives potential from mass-distribution; -Delta u = rho; basis of gravitational + electrostatic potential theory.