In a new section titled “J.K. Rowling’s Thoughts” in the Prisoner of Azkaban section on Pottermore, Rowling candidly admitted how she developed Time Turners.

“I went far too light-heartedly into the subject of time travel in Harry Potter and the Prisoner of Azkaban,” she says in new information published today. “While I do not regret it (Prisoner of Azkaban is one of my favourite books in the series), it opened up a vast number of problems for me, because after all, if wizards could go back and undo problems, where were my future plots?”

Like any good writer, Rowling managed to figure out the concept of Time Turners in, well, time. “I solved the problem to my own satisfaction in stages. Firstly, I had Dumbledore and Hermione emphasise how dangerous it would be to be seen in the past, to remind the reader that there might be unforeseen and dangerous consequences as well as solutions in time travel. Secondly, I had Hermione give back the only Time-Turner ever to enter Hogwarts. Thirdly, I smashed all remaining Time-Turners during the battle in the Department of Mysteries, removing the possibility of reliving even short periods in the future.”

Rowling says fantasy books offer these types of problems regularly. “This is just one example of the ways in which, when writing fantasy novels, one must be careful what one invents. For every benefit, there is usually a drawback.”

The “J.K. Rowlings Thoughts” section differs from the “New from J.K. Rowling” sections we usually see on Pottermore. We prefer these “Thoughts” areas because they remind us of the old F.A.Q. section on her site.