Hogwarts occurring is a passage to the Hog's Head bar that formed before the Battle of Hogwarts. Due to the nature of the Room of Requirement, it is possible that several passages to different locations could be accessed from the Room. The three passages out of Hogwarts that Filch does "not" know about are: A further link between two vanishing cabinets, one in the school and the other in Borgin and Burkes in Knockturn Alley presumably worked until "Chamber of Secrets" when Peeves (persuaded by Nearly Headless Nick) smashed the Hogwarts cabinet. The passage was reopened in "Half-Blood Prince" when Draco
Poltergeist and cognitive dynamics of percipients' interpretation of ambiguous stimuli". Psychologist Donovan Rawcliffe has written that almost all poltergeist cases that have been investigated turned out to be based on trickery, whilst the rest are attributable to psychological factors such as hallucinations. Attempts have also been made to scientifically explain poltergeist disturbances that have not been traced to fraud or psychological factors. Skeptic and magician Milbourne Christopher found that some cases of poltergeist activity can be attributed to unusual air currents, such as a 1957 case on Cape Cod where downdrafts from an uncovered chimney became strong enough to blow a