Would it be possible to disprove reincarnation if one could conduct a population census of the entire universe?
I believe you could disprove reincarnation using this method, but with some big caveats. Basically you’d have to make so many assumptions of the form (assume souls can’t be created) (assume the entire universe is observable) (assume there is zero time between a soul leaving one being and entering another) that the disproof wouldn’t end up being acceptable to anyone who believes in reincarnation in the first place. So my answer would be yes, but not to any useful end other than as a logical exercise.