Looking for Overhaulin' today on Discover I came across a program called Ghost Team, or something similar. It was about a team of people who went to haunted places were there were supposed to be ghosts and set up equipment to catch the ghosts. The only thing I remember is one of the guys, fat, beard, baseball hat, poorly dressed, standing in a room shouting at the ghosts: come out, what are you afraid of? He kept shouting, words to that effect until disgusted I changed channels.
Ghosts, do they exist? Truthfully, I think yes, but not in the style of Caspar, or Marley. I think more in the sense of Ghost, who was that? Patrick Swayze? I think when someone passes away, they may not want to move on, or can't for some reason, may not even believe they're dead, and so they hang around.
From what I've read and been told the major difference between us, and the dead is that they are vibrating at a higher speed. Everything vibrates at a certain level, minerals, plants, animals, etc. If you develop the ability to raise your physical vibratory level, in theory you should be able to move between physical and astral, where the ghosts would be, for instance. Pretty much everybody visits the astral while asleep, and many can astral travel while conscous, but moving the physical body from one level to another and back, seems that would be the domain of the Masters.
Of course I've barely scratched the surface, and there's a lot more to it, but I think I've got the gist of it.