I once crossed swords with a person who was obviously a "professional" of sorts [at least he seemed competent in maths] when I made a comment to another that gravity makes more gravity. This is due to the property of nonlinearity of spacetime/gravity. I supported my claim with a link to the "Einstein online"site which at this time appears to be down. His "reputation" though was eventually tarnished with his rather grandiose claim that he had disproved GR and later the recently three GW discove