I believe that when the mind develops far enough it creates the ability to link on the subatomic (magnetic) level.
To understand this, think of hard drives traveling the earths magnetic fields. When the child's mind develops it locks on to the different hard drives and it stays with the child until death. This would explain the immense capability of the human mind, how some are sensitive to others (ESP) when released upon death become the ghosts, spirits and demons etc that can be "read" from the environment.
Personally I think demons are the spirits of dead aliens that have died on this earth (with unknown capabilities) that are traveling the earth's magnetic fields which influence and are detected by the living.
This can also support some theories of reincarnation
