I enjoyed reading a new adventure with the Harry Potter characters in Harry Potter and the Cursed Child, but after I finished the story I realized there a big problem with it.
Spoilers ahead…
I like stories with time traveling. I read and watch a lot of them, so when time traveling doesn’t make sense, I notice.
Here’s a look at how time travel is used in Cursed Child, what’s wrong with it, and how time traveling could have been used better in the story. I’m focusing only on cause and effect and what’s going on with alternate timelines. I won’t touch the mechanics of Time Turners and what’s different about them in Cursed Child because that could be a separate post. You can read about that on Vulture, Time, or Hypable.
After I finished reading Cursed Child, I made a diagram to keep track of the trips that Albus and Scorpius took:
Albus and Scorpius traveled back in time from their present to the Triwizard Tournament tasks in this order: Task 1, then Task 2, and then Task 3. From Task 3, they traveled back to 1981, to the night that Voldemort killed Harry’s parents.
So what’s wrong?
When Albus and Scorpius disarmed Cedric in Task 1 (Trip 1), they created an alternate reality. They realize that when they return to their present time. But when Albus and Scorpius travel from their altered present time back to Task 2 (Trip 2), everything seemed to be consistent with the original timeline, instead of being different because of their interference in Trip 1. They were able to find Cedric and humiliate him without any changes from what they knew from history.
This happens again with Trip 3—Albus and Scorpio should have seen a version of Task 3 that was altered by their interference in Task 1 and Task 2.
The only way to restore the original timeline is to go back further than the first interference point (Task 1). That happens when the gang goes back to 1981, decides not to interfere with established events, and returns to their present from an unaltered past.
If Albus and Scorpius’s actions during Trip 1 didn’t affect Trip 2, then that means that their actions in the past didn’t matter, except in their present time. But if the changes are only in their present time, and past events weren’t affected, then what led to the present changes?
It’s a paradox.
If Albus and Scorpius can’t change the past, then that voids the objective of going back to save Cedric. Worse, this is inconsistent with time travel in Prisoner of Azkaban, where we saw Harry and Hermione go back in time and rescue Sirius.
Having time travel in Cursed Child that affects the present but not the time in between the first point of interference and the present breaks the time travel rules established in the Harry Potter books.
What’s the fix?
If Albus and Scorpius wanted to fix the alternate realities they created along the way, they should have traveled in the order shown here:
This way, every time Albus and Scorpius went back in time, they would have gone back further than the previous trip: Task 3, then Task 2, then Task 1. Obviously this would have changed the story. Albus and Scorpius would first attempt to save Cedric during Task 3. Then fail and go back to Task 2, and then to Task 1.
What works in their favor is, anything that went wrong on Trip 1 to Task 3 could have been undone on Trip 2 to Task 2. And if there was something they couldn’t fix during the Triwizard Tournament, then the last opportunity to restore the original timeline would still be in 1981, with the decision not to interfere.
Revisiting scenes from the Triwizard Tournament is an interesting way to build a new story, but it would have been more enjoyable if the time traveling was consistent with what we already know about the Harry Potter world.