Theory: How Time Travel Works

Let me convince you…that Cursed Child actually fixes and explains the plot hole problem that is time travel in Harry Potter.*

*Author’s note: Kevin fully acknowledges that he holds a generally favorable opinion of Cursed Child, in staunch opposition to the opinions of many other HP fans, including his colleagues at The Accio! Box. We still love working with each other. We know, how heroic of us.

Spoiler warning: this will contain parts where I discuss the events of Harry Potter and the Cursed Child. So if you don’t want to know what happens in the play or if you are just someone who refuses to engage with it, you might want to stop reading.

Ok, gotta psyche myself up for this one. Woo, I can do this, I can do this, I can do this. Let’s talk about how time travel works in the Harry Potter universe.

First, let’s go over some of the relevant and establishing information we have from the series. In Prisoner of Azkaban, we see Harry and Hermione travel back in time, and via both Hermione and Dumbledore, we’re told that it’s actually an incredibly dangerous thing to do.

So it makes a lot of sense that the Ministry gave that power to a 13-year-old. Albeit an incredibly responsible and trustworthy 13-year-old who eventually becomes Minister of Magic. (Like I said before, Cursed Child will enter into this discussion in multiple ways.)

‘the longest period that may be relived without the possibility of serious harm to the traveler or to time itself is around five hours.’

Dumbledore first stresses the importance of Hermione and Harry being unseen, and then later Hermione tells us that witches and wizards who have meddled with time carelessly have caused terrible damage, sometimes even killing their past or future selves and thereby completely destroying the semblance of logic within this universe.

Pottermore backs up this information with JK Rowling’s brief writings on time travel in the series. The short article states that time travel has its limits. As it stands, according to Ministry research, ‘the longest period that may be relived without the possibility of serious harm to the traveler or to time itself is around five hours.’ It even fascinatingly provides an explanation of the mechanisms of a time turner. As it states, the Ministry has been able to “encase single Hour-Reversal Charms, which are unstable and benefit from containment, in small, enchanted hour-glasses that may be worn around a witch or wizard’s neck and revolved according to the number of hours the user wishes to relive.”

I know I’ve read this before, but it’s striking me as so cool this time that a time turner is basically a charm trapped in a bottle. Like, what! How!

The article goes on to talk about Eloise Mintumble who experimented by travelling back from 1899 to 1402, where she got trapped for 5 days. The Ministry retrieved her from the past, but because of the time she’d spent there, upon being returned to the present, her body aged 500 years and she died shortly thereafter. Not only that, but the things she did in that distant past cause no fewer than 25 people in 1899 to just vanish, because they had been “un-born.”

The Tuesday after she came back lasted two and a half full days, and the Thursday after zoomed by in the span of 4 hours.

And I don’t know about y’all, but this is where my brain starts to hurt. And trust me, the brain hurt is only going to get worse.

The last point the article makes about the danger of long-distance time travel is that if you go back too far, time itself gets disturbed. Because of Eloise Mintumble’s breach of the laws of time, the Tuesday after she came back lasted two and a half full days, and the Thursday after zoomed by in the span of 4 hours. Typical HP tomfoolery. But to wrap up that part of it, as Professor Saul Croaker says, “Just as the human mind cannot comprehend time, so it cannot comprehend the damage that will ensue if we presume to tamper with its laws.”

Now that we’ve got kind of our establishing information, let’s do a quick recap of where we are. So we know that the only legal time travel is within a span of 5 hours. And the only legal time turners are property of the Ministry. We do know that it is possible to travel back further than 5 hours, but that it causes serious damage. And we’ve seen that that damage can happen to both space AND time.

So let’s start by explaining how time travel works just in Prisoner of Azkaban, within these legal limits set by the Ministry.

The kind of time travel we see Harry and Hermione using in PoA can be referred to as a single timeline theory of time travel. You’ll also see other people online calling it things like a single loop, causal loop, etc. And referring to it as a loop becomes really helpful. Basically, if you think about it like a piece of string, we make a loop out of it, but there’s still just one piece of string. And so Harry and Hermione are still traveling in only one direction on the string, it’s just at a certain point, the string has a kink in it that sends the string back in a loop to a certain point. They are then pretty much travelling on this same section of string, which is where the limits of a string metaphor reach their breaking point, until they get back to this same point and exit the loop. Or at least, whatever version of Harry and Hermione you’re tracking. They either start the loop or exit the loop. And this is a pretty simple explanation of time travel. This is the Ministry regulated, legal way to travel through time. The introduction of magic as the means of traveling through time also really helps the explanation along. Because with this Ministry-approved time turner, magic can limit it to a certain type of travel.

So this first part of the theory is exactly that. That Ministry-approved time turners only allow the user to engage in single timeline time travel. Single timeline time travel is convenient and easy, because within it, everything that you do as the future you in the past has already happened. Since everything has already happened, when you travel back, you aren’t really able to change anything. Harry and Hermione have already saved Buckbeak when they travel back. Harry has already saved them from the dementors. Sirius has already escaped. So Harry and Hermione traveling back in time doesn’t really serve to change anything about what would happen. It just kind of ensures that everything does happen.

With legal, single timeline time travel, there is no timeline in which Buckbeak died or Sirius was kissed by the dementors. There is no timeline in which the kids prove that Peter was still alive. It’s just all fixed. Because you’ve already traveled along this piece of string at the same time as future you, you cannot undo anything. And that’s why it’s legal. We get back to Saul Croaker’s quote from earlier to make sense of this. Because our minds cannot comprehend time, so we simply accept that although we view it in a linear fashion, it really is more like Doctor Who, a ball of wibbly wobbly timey wimey stuff.

Now, you’re probably thinking, “What about how Hermione says you CAN go back and kill your past self or your future self. And what about Cursed Child???”

I’m pretty sure none of you were thinking “what about Cursed Child,” right?

So last spoiler warning here, click away right now, but in Harry Potter and the Cursed Child, Albus Potter and Scorpius Malfoy get their hands on an illegal time turner. In their day, all time turners are supposed to have been destroyed due to the fight in the Ministry in Order of the Phoenix. But those were just the Ministry’s time turners. This one that the boys get ahold of is a bootleg time turner, and it’s imperfect because even though it lets you go back more than 5 hours, it only lets you stay for like 5 minutes. However, we see that the boys’ actions with this illegal time turner do indeed allow them to change the past and have repercussions on their present.

We also see another time turner in Cursed Child, and this one gives an even better explanation of time travel and its limits and abilities in the Harry Potter Universe. And that time turner belongs to none other than Draco Malfoy. Well, originally, Lucius Malfoy. But Draco straight up says that his dad had an affinity for collecting really cool and illegal magical items. He brings up specifically that Lucius wanted a time turner that was way better than the Ministry-approved ones. And this time turner we see is kind of the “perfect” time turner if you will. It allows you to travel forward and backward, as far as you want, and to stay as long as you like. Or at least more than 5 minutes. But this and the other illegal time turner are clearly a different kind of time travel.

This type of time travel is more the Doctor Who time travel. The wibbly wobbly timey wimey stuff. Or to be a skosh more academic with it, it could be called dynamic timeline time travel. It would be unhelpful to think of this as a loop this time, because with this, you aren’t just going back and reliving a certain period of time at the same rate. With dynamic timeline time travel, you travel back and then travel forward to where you came from. So that’s partially why you’re able to change things more so in dynamic timeline. You aren’t just kind of rewinding and hitting play again. You are taking yourself up and out of your place in the time wobble and plopping yourself somewhere you don’t belong and never were, until now.

Remember, time is a jumbled mess and is constantly changing in this scenario. Essentially, with this form of magical time travel, you’re taking a piece of the wobble ball and putting it somewhere else. And predictably, that has consequences. Time doesn’t like being torn apart and rearranged. That’s why we see seemingly unrealistic things happening in Cursed Child, like Cedric becoming a death eater. Dynamic timeline time travel has literally wounded the ball of time wibblies, and so time tries its best to repair itself. And just like a big wound on you, after your body tries to put things back together, you’re essentially yourself, but the details are different.

Time is the same way with this kind of time travel. You’ve damaged time, so it repairs itself, and is essentially the same, but the details are different. Like Harry dying in the battle of Hogwarts and therefore Albus is never born in one scenario. And the writers pay fan service to all the people who hate Romione and make it so that in almost every other future scenario, they aren’t together!

But like in Cursed Child, it gets to a certain point where you’ve changed so many things, you just keep going back to try and fix what you’ve changed over and over. And the more damage you do to time, the harder it gets. Eventually, our heroes do figure it out and are able to fix everything. Even their troubled relationships. But we see that if you do too much damage, like Eloise Mintumble, time really lashes back.

And that’s why the Ministry made it illegal to travel more than 5 hours.  The Ministry had done tons of testing and experimenting on the limits of time travel. My theory is that time is stable enough to be messed with during that approximately 5-hour time span, and pretty much if you only travel backward instead of also then traveling forward. Instead of wounding time, you’ve just given it a small scratch. Not even broken the skin. But if you go beyond those 5 hours, if you change too much and do too much damage, time notices, and steps in, and repairs itself. And of course, time couldn’t care less about your opinion of its repairs. Time couldn’t care less that your actions brought about Voldemort Day.

So let’s summarize a bit in case you’ve gotten lost along the way. Goodness knows I have. Time travel in the magical world exists in two ways:

1. Single timeline time travel, which is legal with Ministry approval and regulation, and we see in Prisoner of Azkaban, and in which you cannot change the past.

2. And dynamic timeline time travel, which is illegal and is seen in Cursed Child, and you can change the past.

And that is an extremely simplified explanation of time travel in the HP Universe. Go ahead and let us know what you think in the comments.

So, did I do enough to convince you that Cursed Child has some merit to it? Maybe after reading this, give CC a re-read and see if you at least make any of these connections, too. And as a theatre person, I just need to say, please please please remember that plays are not meant to be read. They are meant to be seen.  So if you do re-read Cursed Child, or if you read it for the first time, remember that you are only getting about one tenth of the intended experience. So if you can, withhold a bit of judgment.