In the classical world, information can be copied and deleted at will. In the quantum world, however, the conservation of quantum information means that information cannot be created nor destroyed. This concept stems from two fundamental theorems of quantum mechanics: the no-cloning theorem and the no-deleting theorem. http://www.physorg.com/news/2011-03-quantum-no-hiding-theorem-experimentally.html It means that our consciousness is written elsewhere in the space due to a certain program. If somebody knows this program he can revive that consiousness.