It is believed that ghosts have not crossed over to the other side. 1. where we are, three dimensional Earth 2. There may be types of ghosts. A number of overnight guests in the Lincoln bedroom have reported seeing Lincoln sitting on the edge of the bed removing his shoes. This suggests a coincidence between timelines which repeats like a movie segment run over and over.
Some sightings are periodic.
There may not be any activity for months, then sightings every day for a week. It would be interesting to record the frequency of these sightings and try to correlate them with known occurrences of solar flares, gravitational fluctuations etc. A detector can be found HERE . Ghost sightings are more frequent in winter months in the Northern hemisphere. It would be of interest to compare this to the Southern hemisphere.