# uniqueness of classical gravity

18 Jan 2023Is classical Newtonian gravity unique in being a linear, parity-invariant second-order theory? Is Maxwell-electrodynamics in a similar way unique, and what assumptions does one need to make?

Is classical Newtonian gravity unique in being a linear, parity-invariant second-order theory? Is Maxwell-electrodynamics in a similar way unique, and what assumptions does one need to make?