Some people believe that ghosts are merely figments of our imaginations.
Others believe that they are visions, or apparitions, of the dead.
Reports of ghostly activity can include non-visual experiences such as noises,
smells or even sensations of coldness.
There are also accounts of ghostly animals, ships and even ghosts of people who are still alive.
The earliest ghost reports are from over 2000 years ago.
One early sighting was recorded by Pliny, a Roman writer.
He told how in the 2nd century AD, a figure in chains appeared to
Athenodorus, A Greek philosopher.
The figure beckoned and he followed it outside, where it disappeared.
The next day, when the area where it had disappeared was dug up,
a skeleton bound in chains was revealed.
Since most ghosts appear infrequently and their appearances are difficult to predict,
attempts to prove that they exist have been largely unsuccessful.
Ghost investigators have to rely on people's accounts for their evidence.
Even if people are telling the truth,
there could be other explanations for what they have experienced.
Some paranormal investigators have suggested that certain apparitions may be recordings of events from a previous era. They believe that these are like video or sound recordings,But what is played back is a scene, sounds or sensations from the past.
Frozen In Time..
The term recording ghosts is given to apparitions that always appear in the same place.
They seem unaware of the people who witness them and of their modern surroundings.
It's as if the ghosts are fixed in time and space.
One explanation that has been offered for ghosts walking through walls is that this type of ghost moves around a building as it was in its own time.
People have suggested that when a ghost walks through a wall, it is because there used to be a door there.
How Are Recordings Made?
When we are afraid or stressed, we produce a high level of emotional energy.
One theory offered to explain recording ghosts suggests that under certain conditions this energy is stored at a particular location. So, if someone is distressed they may leave an emotional imprint or recording, which lingers after their death.
No clear scientific argument has been offered to explain how this happens.
It has been suggested that the presence of a particular mineral in the walls or surrounds may be relevant, for example, the mineral quartz produces an electric field when pressure is applied to it.
Perhaps this enables it to store information it is though that the recording may be replayed when the conditions are changed in some way.
Without more evidence, it's difficult to view these theories as anything more than speculation.