This is my first time posting on this forum, or any for that matter, so I appologise in advance for any mistakes I may make. Also, as I only have an 8th grade education, I cannot describe my theory by use of equation or the like.
My theory is that when a person dies, they become a "ghost." I mean a ghost in both the traditional term and a non-traditional term. Traditional in that the ghost is the remains of a human left on earth. Non-traditional in that it is not a soul and does not exist in a spectral state. As a human grows and lives out life, their mind collects information. When a human dies, their mind cannot support the information any longer. However, information cannot be destroyed. I theororize that this information takes on an intangable form. Intangable because information does not have mass. This collection of information left over from a human's death would contain said human's thoughts, personality, memory, etc. This would cause the ghost to, in effect, be the human that the information came from. I have researched this to the best of my ability and have yet to find anything that disproves this theory. If anyone does find something that contradicts this, please tell me.