What do you think Poltergeists or Spirits/Ghosts, Paranormal Entities Are?
Projection Of Our Fears, Manifesting Into Reality
Projections Of People From a Parallel Universe/Other Dimensions
Wandering Souls, Longing To Return Home to The Spiritual Realm
Glitches In The Matrix/Simulated Universe
illusions or mirages caused by the mind
Nothing But The Wind