Ghosts in Lowell Was Right

Instead of being largely debunked, Spiritualism proves to be partially vindicated.  Ghosts exist, and mediums are able to make contact with them.   However, as they begin to be better understood, it becomes clear that ghosts are not exactly the souls of the dead, but bits of psychic energy that remain after emotional turmoil, carrying with them the feelings and the knowledge of those tormented souls.   The most common event that leaves behind a ghost are death agonies, but other events can prompt them as well, and living individuals may have ghosts in the world.  The majority of people leave behind a ghost upon death,  but persons who die peacefully frequently do not.

Ghosts can be contacted by individuals with psi powers and who possess the necessary skill of .  In séances , they can allow others without psi powers to experience and speak with the ghost as well, but this requires the use of a psionic amplifier of some sort.

Ghosts possess the knowledge of the person at the time the ghost was created.  They have no knowledge of events in a the life (if any) of the person forming the ghost subsequent to the point at which they were formed.  They have difficulty in retaining any new memories and so remain mired in the past.

Ghosts are frequently insane from the agonies which create them.  They are always less than full, well-rounded individuals and are focused on whatever was the concerns of the person who formed them at the time of their formation.

The psychic energy of a ghost is always attached to a particular object such as a building, a natural object (tree, boulder, etc.), or personal item owned by the individual (weapon, portrait, jewelry, etc.).  Destroying the item banishes the ghost.  Ghosts may also be exorcised without destroying the object by a sufficiently strong psychic.
Persons with psionic abilities and emotional problems can be possessed by ghosts.  In this case the ghost is able to once more have a full life experience.  The ghost can be exorcised, in which case the ghost is destroyed.

Some alien cultures have learned how to deliberately form ghosts and this has become part of their technology.  Ghosts are deliberately created to act as expert systems and to preserve the knowledge of the past.  In some cultures, creating a ghost is considered the appropriate final action of an individual  in the last moments of life.  Psionic devices and drugs have been developed to which aid in the formation of a ghost.   This technology has now passed into human hands and trained psionic individuals can form ghosts at will.

Creating a ghost requires one point of psi power which remains lost for the duration of the ghosts existence.  Temporary ghosts may be produced which vanish after a period of time but permanent ghost imply the permanent loss of psi power.   Permanent ghosts are therefore commonly only formed by persons in the last stages of life.  Because of these limitations, items haunted by expert ghosts are necessarily rare and expensive.