Time-Turner

"My use and value unto you are gauged by what you have to do. I mark the hours every one nor have I yet outrun the sun."

- Inscription on Hermione Granger's Time-Turner

The Time-Turner is a device capable of time travel. The Time-Turner resembled an hourglass on a necklace. The number of times one turns the hourglass corresponds to the number of hours one travels back in time. It is extremely important that the user of a Time-Turner not be seen by past or future versions of themselves unless, of course, said versions are aware of their usage of a Time-Turner. A possible scenario is a wizard/witch killing their past or future selves by mistake.

History
"I can't stand another year like this one. That Time-Turner, it was driving me mad. I've handed it in."

- Hermione Granger at the end of her third year

Hermione Granger received one from Professor McGonagall in 1993 so she could attend more classes in her third year than time would allow. Since McGonagall made her swear to not tell anyone about it, she did not mention it to Harry or Ron until the end of the school year, when she and Harry used it to travel back in time and save Sirius Black and Buckbeak from certain death. Special permission from the Ministry of Magic had to be sought to allow Hermione to use one, but her academic record ensured that permission was given.

Hermione found her third year stressful with the extra class load and also decided to drop Divination, which she despised, and Muggle Studies, which she did not find very useful, given that she was a Muggle-born. This allowed her to have a normal schedule once again, and she returned her Time-Turner. Ron was disappointed that Hermione did not tell her friends about it, despite her promise to McGonagall.

Behind the scenes

 * It is possible that Barty Crouch Jr, Percy Weasley, and Bill Weasley used the Time-Turner, as they are known to have achieved twelve O.W.L.s.
 * During the Battle of the Department of Mysteries in 1996, the Ministry's entire Time-Turner supply was smashed. It is unknown when or if the Ministry replaced them, or if it is even possible.
 * During Hermione's third year at Hogwarts, despite the fact that no one is supposed to be seen by their past or future selves, it is possible that she may have seen herself in the halls, although this is never mentioned.
 * In the film version of Harry Potter and the Prisoner of Azkaban, Harry and Hermione were seen by the executioner twice, having walked past him scowling, then ran past him again while "retracing their steps."
 * While in the book the Time-Turner takes you back to the place you were present at that time, the movie version has the user stay in the same place as when they used it. The GBA video game version has the user appearing at an entirely random place (Harry and Hermione use it in the Hospital wing and appear at the Forbidden Forest).
 * The possibility of time travel within the Harry Potter universe may seem to allow many plot holes, but characters appear to use them for trivial tasks that have no effect on existence as a whole. The one notable use of a time-turner within canon, the Rescue of Sirius Black and Buckbeak, obeys the Novikov Self-Consistency Principle. This theory of time-travel, stating that "Nothing can be changed because anything a traveler does merely produces the circumstances they had noted before traveling," is incidentally reminiscent of J. K. Rowling's employment of self fulfilling prophecy, but while prophecies within canon are relevant only to the degree that characters place relevance on them, as the books state Harry Potter and Tom Riddle could walk away and void the prophecy if they chose to, the same cannot be said for the series if any major events within the books or the Harry Potter universe as a whole have been related to the time turners' misuse.
 * Although the Time Turner could allow the user of it change other people's futures (eg.Death), it is impossible for the person in the future time where the user has came from to have already died in his own time.

Appearances

 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Half-Blood Prince -Lego Harry Potter Years 1-4

Notes and references
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