Ghosts
Ghosts are often seen to be of a human size and shape (although some
accounts also mention animal ghosts), but they are often described as not visually striking. Usually these depictions suggest that the ghost does not consist of solid matter. The Western theory of a ghost is semi-transparent, and does not directly interact with physical objects.
The ghosts of the Western belief can defy physics, such as walk through
walls and float above the ground. Ghosts are often said to behave as if they were mindlessly following a particular routine or itinerary. Other ghosts are described as being solid, interacting with their environment, and generally behaving much like other people. In some ghost stories, especially in the Caribbean and Africa, the figure is only identified as a ghost because an acquaintance knows that the person is already dead.
In the West, those who believe in ghosts sometimes hold them to be souls
that could not find rest after death and so linger on Earth. This inability to
find rest is often explained as unfinished business, such as a victim seeking justice or revenge after death. It is sometimes held that ghosts reside in Limbo or Purgatory. Although this view was once propounded by some Catholic theologians, it is no longer believed according to the Catechism of the Catholic Church. It is worth noting that while many mainstream Protestants and Evangelical Christians believe in the existence of principalities, they do not believe in ghosts (as spiritual manifestations of the dead) and would generally attribute more violent ghosts, such as poltergeists, to the actions of demons.
Some ghost researchers approach the possibility of ghosts from a more scientific standpoint. Those who follow this approach most often believe that ghosts are not actual disembodied souls or spirits , but rather they are impressions of psychic energy left behind by a deceased (or in some rare cases, still living) person. They assert that traumatic events (such as a murder or suicide) cause mental energy of some kind to be released into the world, where it may be experienced by other people who are sensitive to its presence.
Parapsychologists refer to the "substance" of which ghosts and other spirits are made as "ectoplasm." This way of thinking classifies ghosts in the same category of preternatural unexplained phenomena as poltergeists/telekinesis, ESP, and telepathy. Theories from this approach often encounter difficulties in explaining ghosts that appear to be sentient, such as those which appear to answer questions or react to specific actions from people present. However, it is claimed as a possibility that enough of a dead person's psyche might be imprinted on an environment so as to give the likeness of thought or autonomy.
There is also at least one religion, Spiritualism, that tends to use scientific-looking elements when explaining ghosts. According to Spiritualists, ghosts are the deceased continuing to live in one or more parallel dimensions of sorts, existing in different "frequencies" from our own dimension. Those parallel ghost realities would have all sorts of ghost creatures, plants, objects - even whole "ghost cities". It seems that occasionally portions of those dimensions would overlap with ours, causing ghost sightings. And there would also be living people - mediums or psychics - with the ability to see, hear and speak through the dimensional barriers.
This approach however does not clarify the process by which a living being leaves a "double" at one of those ghostly dimensions at the moment of his/her/its death, or (considering another Spiritualist claim) during dreaming. However, Spiritualism does assert that it is the physical body that is short-term, while the spiritual one is eternal and constantly learning and growing through impermanent physical manifestations. The spiritual life is the gel that holds together the acquired information and lessons
from various physical manifestations through the process of reincarnation.
Both the West and the East share some fundamental beliefs about ghosts. They may wander around places they frequented when alive or where they died. Such places are known as "haunted"; the rounds they go on are known as "hauntings". They often wear the sort of clothing in which they would have been seen when alive. Many cultures believe in demons, devils, and negative energies. Many times such cultures also believe that these may be, or be related to, ghosts, and that they may trouble humans in various ways, such as possession, influence upon thoughts or emotions, nightmares, voices, cold spots, and various sicknesses. They may give a feeling of being watched or of fear.
While some accept ghosts as a reality, many others are skeptical of the existence of ghosts. Much of the scientific community believes that ghosts, as well as other supernatural and paranormal entities, do not exist.
The current tentative consensus among parapsychologists is that ghosts are not the spirits of deceased humans, but psychic imprints which have been left behind, often because of especially strong emotions in the persons who leave the ghost.
Sometimes ghosts are associated with electromagnetic disturbances, which suggests that they might be attributable to the electromagnetic field and not to a presently dead person. Often, videos of paranormal
investigators will show them using E-field or B-field detectors and finding "ghostly" results near wall outlets and electrical appliances.
Psychological factors may also relate to ghost sightings. Many people exaggerate their own perceptions, either when visiting a place they believe to be haunted, or when visiting a site which they know unpleasant historical events have occurred. Certain images such as paintings and movies might "program" a person to automatically associate a certain structure or area with ghosts.
In the end its down to the individuals own perceptions and experiences.