I think people need to stop expecting theories developed to explain the physical world to be able to explain such notions. This whole question is like wonderin

I think people need to stop expecting theories developed to explain the physical world to be able to explain such notions. This whole question is like wondering about what lies outside of the universe or why it exists. There are some things which are simply most likely unknowable due to information being inaccessible from our point of view. Maybe someone can try merging their consciousness with someone else's via a brain graft or something else (callosotomy?) to see what happens... for the rest of us death is the only real experiment we'll have the luxury of carrying out.