There is no proof of anything, Heavan, Hell, or spirits, they are as likely as anything, rencarnation, oblivion, turning into a star, I don't think that they need be our only options for the possibiblities of after death, and whose to say that the universe exists linearly anyway, you might come back 200 years ago ... so I will go with my very aganostic answer of ...?
What do think is the truth about UFO's?