Physics professor: Some scientists claim that superheated plasma in which electrical resistance fails is a factor in causing so-called ball lightning.  If this were so, then such lightning would emit intense light and, since plasma has gaslike properties, would rise in the air. However, the instances of ball lightning that I observed were of low intensity and floated horizontally before vanishing. Thus, superheated plasma with failed electrical resistance is never a factor in causing ball lightning.
All types of ball lightning have the same cause is an assumption required by the physics professor's conclusion.