A possible world is a way in which it is logically possible (does not result in contradiction) for reality to exist. There is a possible world in which everything is exactly the same, but it is 1 degree warmer than it is now; there is a possible world in which COVID-19 never existed; there is a possible world in which everything is exactly the same, but there is +1 more person existing right now. What is the nature of these possible worlds, and specifically, what is the nature of my relationship to myself in these possible worlds?