“I don’t understand why you qualify with “non-linear”, but maybe I don’t understand it well enough.”
With Newtonian gravity only the mass is counted. In General Relativity both mass and energy effect gravity.
hmm... ok... so... I am still puzzled by the “non-linear” characterization. I am not sure what “non-linear” space would be, similarly unclear what “non-linear” spacetime would be.