Scientifically speaking, it is possible. Human nerve system, run on electric, to a certain extend this electric energy, is our conscious, the nerve sent electric pause to our brain and our brain function, using the same electric energy. And in the law of physic, eneregy cannot be create or destroy, it can only transfer from one form to another. Even more, the energy use by our body enter us, before we are born and only leave, after dead, no additional energy enter or leave our body, during this time. If no energy enter, the baby won't be able to come to life. We can easily argue, this energy is what we commonly consider as souls and a soul without a body, is a ghost. We can also easily argue, this is the true form of the gods and demons. When the energy of a former host enter a new infant body, that might be what we commonly think of as reincarnation.