I'm sure this has already been discussed before, so feel free to provide a link to past discussions. What if a person is annihilated, and then an EXACT replica of him is created. Since it's exact, the new person should have the same memories as the old one. So would being annihilated and then recreated feel just like falling asleep and then waking up? I.e. is this was done to you, would the new person still be you? But then, what if two or more replicas of the original person were created instead of just one? Which of them would be the original person, and which of them would be his twin? I.e. in which body would the original person's consciousness be? Could it be in two places at one? This seems inconceivable, but that by itself doesn't mean that it's impossible. Maybe the original person's consciousness would ceasse to exist, and we would have two new people, neither one of which feels like he fell asleep and then woke up? Or is there some physical principle which prohibits such an experiment, even in theory, thus making the above questions meaningless?