@sbjohnsrpi @snow This is exactly why we like to believe that flathearthers are just ignorants or trolls. Convincing someone that homeopathy is wrong or that the earth is not flat, same process: appealing to some basic knowledge they were supposed to have acquired at school, add some "paraphrasing" of primary data that invalidates their "belief" and "justify ours, maybe show them a picture that proves you're right, all of these based on primary data that is inaccessible to them in both cases.