You're right.
There are energy lines.. kinda like a grid, covering the planet.

Everything around us, including us, is energy, and that energy can be imprinted on the fabric of time.

Alot of ghost sightings are simply a "playback", however there are other spirits that are angry that they are dead (poltergheists) or have a very strong emotional bond with a person or place etc. and simply refuse to leave.
(TheRiddler Hmmmmm... I concur., Fri 4 Jul 2008, 11:15, Reply)