In the magical world (in Harry Potter) can ghosts use magic?
Can magic be used on ghosts?
Or, once they become ghosts, can they interact with magic at all?
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Sign up to join this communityIn the magical world (in Harry Potter) can ghosts use magic?
Can magic be used on ghosts?
Or, once they become ghosts, can they interact with magic at all?
I'm not sure if it's proof, but ghosts put together some food for Nearly Headless Nick's deadthday party. Assuming it wasn't Hogwarts' house-elves who did it, presumably this means they did it by magic.
On a related note, they exchanged letters (invitations/rejections for Headless Hunt). That also seems to imply using magic.
Nearly Headless Nick was petrified by the Basilisk in Chamber of Secrets, thus interacted with magic.
While Nearly Headless Nick's encounter with the Basilisk, and his subsequent "un-petrification", implies that magic can be used upon ghosts, there is no reason to believe that, conversely, ghosts can use magic.
The presence of food at the ghost party in CS8 is no indication of magical powers whatsoever. To begin, it's rotten food, probably the left-overs provided by the Hogwarts elves. Even if not, food is the 1st exception to Gamp's Law of Elemental Transfiguration:
"Your mother can't produce food out of thin air," said Hermione. "no one can. Food is the first of the five Principal Exceptions to Gamp's Law of Elemental Transfigura --" (DH15)
The fact that ghosts can exchange mail among them also does not imply the use of magic. Nick is described pulling a letter out of his pocket. As ghosts can wear clothes, it is reasonable to assume that they can also carry and exchange (among themselves!) belongings. Neither of these consists of physical matter but is a property of the appearance of the ghost. Therefore, no magic other than the ghost's existence is implied.
"But you would think, wouldn't you," he erupted suddendly, pulling the letter back out of his pocket [...] (CS8)
I would argue that if ghosts had "concrete" magical powers, then Myrtle would have inflicted corporal vengeance on her bully Olive Hornby, not simply haunted him. Also, she would have reacted to Ginny throwing Riddle's diary at her.