As the HBO Harry Potter series is filming, the makers should officially explain one of the Potter lore's most contentious topics: time turners. Introduced in the third book and the movie, Prisoner of Azkaban, fans have asked questions as to why it wasn't used to stop Voldemort's rise, or even undoing the deaths of Lilly and James Potter.
However, over the years, author J.K. Rowling has written an extensive reason why time turners aren't used to go back decades or centuries in the past. Everyone knows that since Harry Potter and the Order of the Phoenix, time turners and the entire concept of time is studied in the Wizarding World by the super-secret Department of Mysteries, and the people who worked for it, the unspeakables.
Thus, the HBO series needs to briefly set up the Department of Mysteries in the first season itself and then explain the rules of time travel in the Wizarding World in the third season.
Harry Potter's time turners explained:
As mentioned before, a time turner is introduced in the third book, Harry Potter and the Prisoner of Azkaban. One of the Ministry of Magic's time turners is handed over to 13-year-old Hermione Granger, so that she can attend all her classes. Wizards use time turners for time traveling purposes; Hermione uses hers to attend the classes.
As we know now, Sirius Black is innocent, as Wormtail is revealed to be the man who betrayed Harry's parents to Voldemort. But the rest of the Wizarding World doesn't know this, and Sirius is about to be given the Dementor's Kiss. Harry and Hermione try to convince Dumbledore to save Sirius, but Dumbledore hands them a mission to save Sirius by travelling back in time.
They successfully manage to save Sirius and even Buckbeak from their grisly fates by the end of the book. After the third book, time turners make a return in the fifth book, Order of the Phoenix, where they are destroyed as Harry, Ron, Hermione, Neville, Ginny, and Luna battle Death Eaters in the department of mysteries. This battle ended the Wizarding World's ability to travel back in time.
This was ultimately contradicted by 2016's Harry Potter and the Cursed Child, which brought back two time turners, but utterly failed to stick to the established lore of time travel in the Wizarding World as well.
Time travel in the Wizarding World is dangerous
In August 2015, a year before the release of Harry Potter and the Cursed Child, Rowling revealed the reason why wizards never travel back in time to stop Voldemort. Through a Pottermore post, Rowling revealed to fans how dangerous time travel is in her fictional world. She told the story of a young Unspeakable named Eloise Mintumble, who, along with her colleagues, was responsible for studying time.
These Unspeakables were trying to determine why some of their colleagues who travelled centuries back in time were not returning. To test, Mintumble travelled back from her present of 1899 to 1402, i.e., around 500 years in the past. Mintumble was stuck in 1402 for five days. And when she returned to 1899, her body aged five centuries and died shortly.
Other than her grisly fate, this is not the only problem. Over five days, several people were wiped out of existence, and days either extended or passed by swiftly. The post reads:
"‘Finally, there were alarming signs, during the days following Madam Mintumble’s recovery, that time itself had been disturbed by such a serious breach of its laws. Tuesday following her reappearance lasted two and a half full days, whereas Thursday shot by in the space of four hours. The Ministry of Magic had a great deal of trouble in covering this up and since that time, the most stringent laws and penalties have been placed around those studying time travel.’"
This is why the Wizarding World has restricted time travel to a matter of hours, as we see in Harry Potter and the Prisoner of Azkaban.
Do you think that the HBO Harry Potter show will include this key detail from the Wizarding World lore?