Do ghosts really exist? Well, if scientists are to be believed, they do but "in the mind" only.
The researchers at the University College in London have found that that when people gaze around in a poorly lit context, it can fool their brains into seeing things that are not really there.
"The context surrounding what we see is all important - sometimes overriding the evidence gathered by our eyes and even causing us to imagine things.
"Illusionists have been alive to this phenomenon for years. When you see them throw a ball into the air, followed by a second ball, and then a third ball which 'magically' disappears, you wonder how they did it.
"In truth, there's often no third ball - it's just our brain being deceived by the context, telling us that we really did see three balls launched into the air, one after the other."
"This could also be why monsters tend to lurk in the shadows. In shadows many things are seen vaguely (rather than clearly), thus tending to trigger the filling in," 'The Daily Telegraph' quoted lead researcher Prof Li Zhaoping as saying.