Poltergeist (from German poltern, meaning to rumble or make noise, and Geist, meaning "ghost", "spirit", or "embodiment") denotes a demonic spirit or ghost that manifests itself by moving and influencing objects.
Historically, several different hypotheses have been put forward to explain the poltergeist phenomenon.
Caused by Physical Forces
Poltergeists are ghosts that make noises or move objects through the air. Some scientists and skeptics propose that all poltergeist activity that they can't trace to fraud has a physical explanation such as static electricity, electromagnetic fields, ultra-, and infrasound and/or ionized air. In some cases, such as the Rosenheim poltergeist case, the physicist F. Karger from the Max-Planck-Institut für Plasmaphysik and G. Zicha from the Technical University of Munich found none of these effects present and psi proponents claim that no evidence of fraud was ever found, even after a sustained investigation from the police force and CID, though criminologist Herbert Schäfer quotes an unnamed detective watching the agent pushing a lamp when she thought nobody was looking. However, whether this is true or not, police officers did sign statements that they had witnessed the phenomena. Other aspects of the case were hard to explain: The time service was rung hundreds of times, with a frequency impossible with the mechanical dialing phones of 1967. The municipal authority disconnected the office from the mains supply and hooked it up to a dedicated generator hoping to stabilize the current. But surges in current and voltage still occurred with no detectable cause according to Zicha and Karger. Others think poltergeist phenomena could be caused by more mundane phenomena, such as unusual air currents, air vibrations such as in acoustic levitation, or tremors caused by underground streams.[Citation Needed]
John Hutchinson has claimed that he has created poltergeist effects in his laboratory. Also worth noting is that scientist David Turner proposes that poltergeists and ball lightning may be linked phenomena.  Some scientists go as far as calling them pseudo-psychic phenomena and claim that under some circumstances they are caused by obscure physical effects. Parapsychologists William G. Roll and Dean Radin, physicist Hal Puthoff and head of electrical engineering at Duke University who specializes in electromagnetic field phenomena, claim that poltergeist phenomena [the movement of objects at least] could be caused by anomalies in the zero-point field,  this is outlined in the above article and in Roll's book Unleashed and mention is made of it in a chapter of Dean Radin's book Entangled Minds. The basic theory is that poltergeist movements are repulsive versions of the casimir effect that can put pressures on objects. Thus, anomalies in this field could conceivably move objects. This theory has also been mentioned in the current book on paranormal phenomena Science by Marie D. Jones.
The theory is not complete, however, because it accounts for the movement of objects but not for the strange voices, seeming personality, and strange electrical effects displayed in some cases.
Self-delusion and Hoaxes
Skeptics think that the phenomena are hoaxes perpetrated by the agent. Indeed, some poltergeist agents have been caught by investigators in the act of throwing objects. A few of them later confessed to faking.
Skeptics maintain that parapsychologists are especially easy to fool when they think that many occurrences are real and discount the hoax hypothesis from the outset. Even after witnessing first hand an agent throwing objects, psi-believing parapsychologists rationalize the fact away by assuming that the agents are only cheating when caught cheating, and when you do not catch them, the phenomenon is genuine. One reason given is that the agents often fake phenomena when the investigation coincides with a period of time where there appears to be little or no 'genuine' phenomena occurring. Another stated reason is that some of the phenomena witnessed would be hard to fake, even for magicians when under the watch of many people, let alone untrained children and non-magicians.
The current most agreed upon hypothesis among most scientists is a mixture of the self-delusion and hoax hypothesis and a bit of the caused by scientifically explained forces hypothesis [tremors, abnormal air currents etc ]
Famous Poltergeist Infestations
Although poltergeist stories date back to the first century, most evidence to support the existence of poltergeists is anecdotal, which is hardly surprising as the nature of the phenomenon is unpredictable and sporadic. Indeed, many of the stories below have several versions and/or inconsistencies; however there are a few that do not, for example, the Miami poltergeist has event records signed by all witnesses as to the way things happened. These witnesses include police officers, a skeptical magician, and workers at the warehouse. The Rosenheim case is another, with multiple witnesses and unexplained electric and telephonic phenomena.
- An "evil spirit" threw stones and made the walls shake in a small farmhouse. This was the first recorded poltergeist case. (858)
- Drummer of Tedworth (1661).
A pamphlet printed in London in 1698 by Mr. Ricard Chamberlain provides an account of a poltergeist-type haunting that had occurred some years before. Two copies of the pamphlet exist in the British Museum called: "Lithobolia, or stone throwing Devil. Being an Exact and True account (by way of Journal) of the various actions of infernal Spirits or (Devils Incarnate) Witches or both: and the great Disturbance and Amazement they gave to George Walton's family at a place called Great Island in the province of New Hampshire in New England, chiefly in throwing about (by an Invisible hand) Stones, Bricks, and Brick-Bats of all sizes, with several other things, as Hammers, Mauls, Iron-Crows, Spits, and other Utensils, as came into their Hellish minds, and this for space of a quarter of a year....", some cases, these types of spirits share aspects with elves and goblins.
- The "Wizard", Livingston, West Virginia (1797).
- The Bell Witch (1817).
- The Haunting of The Fox sisters (1848) - arguably one of the most famous, because it started the Spiritualism movement.
- Hopfgarten near Weimar (1921).
- Eleonore Zugun - The Romanian 'Poltergeist Girl' (1926).
- The Borley Rectory phenomena (1929).
Borley Rectory (1937)
William Roll, Hans Bender, and Harry Price are perhaps three of the most famous poltergeist investigators in the annals of parapsychology. Harry Price investigated Borley Rectory which is often called "the most haunted house in England."
Dr. Friedbert Karger was one of two physicists from the Max Planck Institute who helped to investigate perhaps the most validated poltergeist case in recorded history. Annemarie Schneider, a 19-year-old secretary in a law firm in Rosenheim (a small town in southern Germany) was seemingly the unwitting cause of much chaos in the firm, including disruption of electricity and telephone lines, the rotation of a picture, swinging lamps which were captured on video (which was one of the first times any poltergeist activity has been captured on film), and strange sounds that sounded electrical in origin were recorded. Fraud was not proven despite intensive investigation by the physicists, journalists, and the police. The effects moved with the young woman when she changed jobs until they finally faded out.
In the Rosenheim case of 1967 , The Rosenheim Poltergeist (1967).  (German and most extensive).   Friedbert Karger's whole perspective on physics changed after investigating the events. "These experiments were really a challenge to physics," Karger says today. "What we saw in the Rosenheim case could be 100 per cent shown not to be explainable by known physics." . The phenomena were witnessed by Hans Bender, the police force, the CID, reporters, and the physicists. The claims were aired in a documentary in 1975 in a series called "Leap in the Dark."
- The Black Monk of Pontefract 
- The Enfield Poltergeist (1977).
- The Miami Poltergeist, a poltergeist witnessed by police and a skeptical magician who did not believe it was a ghost, but admitted he witnessed phenomena he could not explain. Many others witnessed phenomena including reporters, parapsychologists, and workers at the warehouse.
- The Mackenzie Poltergeist (fairly recent) - Famed for haunting Greyfriars church yard, Edinburgh, UK.
- The Canneto di Caronia fires poltergeist (fairly recent (2004-2005)) - Famed for defying all attempts at a scientific explanation, Sicily, Italy .
- The Entity Case allegedly involved a single mother of three named Carla Moran who was being repeatedly raped by an invisible entity and its two helpers over the course of several years.
- The case of Tina Resch, widely reported in the media in 1984.
- A recent case in Barnsley near Sheffield in England, where poltergeist effects were witnessed by the police force. 
- In Denver, Colorado there have been several reports of unknown forces positioning toys, furniture, and objects in patterns and strange positions.
- The Thornton Road poltergeist of Birmingham (1981).
- Easington Council in County Durham, UK paid half of a medium's fee so that she would exorcise a poltergeist from public housing in Peterlee as it was deemed more cost effective than relocation of the tenant (2008). 
- 'Turner thinks ball lightning might cause the spooky movement of objects blamed on "poltergeists".' in 
- "Physicists probe the paranormal". psychicsworld.com (2000-05-01). Retrieved on 2007-10-30.
- Roll, W. Poltergeists, Electromagnetism and Consciousness PDF at ,
- Jones, Marie D. PSIence: How New Discoveries in Quantum Physics and New Science May Explain the Existence of Paranormal Phenomena (New Page Books, 2006)
- Fairley, John; Welfare, Simon (1984). Arthur C. Clarke's World of Strange Powers. London: Harper Collins. ISBN 0002166798. Pages 28-31
- "Council pays psychic for exorcism". BBC News (2008-02-12). Retrieved on 2008-02-13.
- Some conjectures about the mechanism of poltergeist phenomenon by Pierro Brovetto and Vera Maxia, NeuroQuantology, Vol 6, No 2 (2008). Technical paper proposing hypotheses for pyrokinetic and telekinetic events reported in poltergeist cases involving young girls going through puberty. PDF link to full paper in sidebar, Italian to English translation.
- Poltergeist caught on video, The Sun UK newspaper, August 9, 2008. Footage of a water bottle suspended at an angle and wounds appearing on a victim's back. South Shields poltergeist case, 2006. Location: Borough of South Tyneside, England.
- Andrew Lang, The Poltergeist and his explainers, The Making of Religion, (Appendix B), Longmans, Green, and C°, London, New York and Bombay, 1900, pp. 324-339.
- Haunted Ontario - Founded in 1996 by Bob Milne, Haunted Ontario chronicles the ghosts, spirits, spooks, and poltergeists said to haunt Canada's most populated province.
- Poltergeist: The Legacy Website
- Dehaunting Techniques
- International Journal of Parapsychology
- Princeton Engineering Anomalies Research
- Skeptic's Dictionary
-  The Entity Case
- 1926 silent short film of the Eleonora Zugun poltergeist case On YouTube, with German title cards.