Time Turner Problem - See Yourself

Question

There is a question I wanted to ask some time ago and I'm not quite sure it hasn't been answered already. In fact if so, I did not find anything.

At the moment I do not have the books with me, but I think I remember that Hermione says something like:

"Imagine you go back in time and then see yourself"

Here is my question, why would it be such a big thing? Especially in Hermiones case. I mean of course if she meets herself in a period before she knew about the time turner, then she would be pretty surprised. But what's the big deal about seeing yourself while in the past, when you already know about the time turner. You shouldn't be as shocked as she states in the book, should you? So my question is, why did Hermione state, that it would be a really shocking scene if you see yourself?

Answer 1

Hermione thinks that were she to travel back in time, her past self might see her future self.

If your past self saw your future self, who knows what crazy affects that could have? Your past self could think you were some evil duplicate and attack or have you apprehended.

Their magic mixing with your time travel magic could cause all sorts of time paradox shenanigans. While Hermione is probably very aware of all this, she's making a point of telling her friends to impress upon them the severity of such an occurrence.

EDIT

Here are the specific reasons she gives Harry.

"Harry, what do you think you'd do if you saw yourself bursting into Hagrid's house?" said Hermione.

"I'd -- I'd think I'd gone mad," said Harry, "or I'd think there was some Dark Magic going on --"

"Exactly! You wouldn't understand, you might even attack yourself! Don't you see? Professor McGonagall told me what awful things have happened when wizards have meddled with time.... Loads of them ended up killing their past or future selves by mistake!"

Answer 2

The Harry Potter Wiki page on Time explains what once happened with time travel:

In 1899, the Department of Mysteries conducted its last experience concerning time-travelling back in time for more than a few hours. Eloise Mintumble was sent to the year 1402, wherein she became stuck for a period of five days. When she was finally retrieved to the present, her body had aged five centuries, and, irreparably damaged, she died in St Mungo's Hospital for Magical Maladies and Injuries.

Her excursion to the past provoked a great disturbance to the life paths of all those she met, changing the present so dramatically that no fewer than twenty-five of their descendants vanished in the present, having been "un-born". Moreover, there were a few more alarming signs that time itself had been disturbed: 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 covering up the mishap and, since then, the most stringent laws and penalties have been placed around those who study time travel.

(Source)

Now, this particular incident was what happened from travelling back about 450 years, albeit substantially longer than the period that occurred in Prisoner of Azkaban. Nevertheless, consider the following regulation, one of hundreds:

The longest period that can be travelled back in time without serious chance of harm to the traveller or time itself is around five hours.

(Source)

Now, to address this specific question, if you saw yourself from the past, even if your past-self did know you had a time turner, surely the temptation to know what the future entails would be too much ("Hey - what's in the exam in a couple of hours?") Consider the effects that this could have in terms of creating paradoxes.

If you didn't know that you had a time turner, you would probably turn mad at seeing yourself! You would at least be quite disturbed by it and this would probably cause a paradox, as if you were disturbed prior to getting the time turner and didn't end up getting the time turner, how could you travel back in time and see yourself? This is more of a general time-travelling paradox i.e not specific to the Potterverse, but it's probably the reason behind Hermione saying what she did.

Answer 3

Think about it this way: Hermione wouldn't be surprised, she had travelled in time before, and would realize that if she saw herself. Harry, however, hadn't. He wouldn't understand it, and as you can see in Ingu Sharma's answer:

"Harry, what do you think you'd do if you saw yourself bursting into Hagrid's house?" said Hermione.

"I'd -- I'd think I'd gone mad," said Harry, "or I'd think there was some Dark Magic going on --"

"Exactly! You wouldn't understand, you might even attack yourself! Don't you see? Professor McGonagall told me what awful things have happened when wizards have meddled with time.... Loads of them ended up killing their past or future selves by mistake!"

However, that is not all!

A scare wouldn't be the only thing that would happen if one saw their future self. That would probably also affect what they did and how they did it. Imagine Hermione saw herself at that night. She wouldn't be surprised, as she would understand that was the effect of the time turner. However, she would know that something had gone wrong, after all, she knew she wouldn't be using it had everything gone "Normal". That could cause her, for instance, to attack Sirius on sight, thinking that Ron had died (since she saw herself with Harry, but not Ron).

If one little thing went wrong, something horrible could end up happening. Hermione understands that, as the brilliant witch she is, so she would be worried about herself too. Not about thinking she had an evil-magic duplicate, but she wouldn't be acting with a Bias that could end up badly.

Answer 4

Like others said before don't think the issue is as much with Hermione seeing herself but rather with Harry seeing himself or someone else seeing two Hermiones or two Harrys.

As mentioned before Hermione seeing her future self would be unlikely to react as strongly as Harry seeing himself but it could cause a change in her past self's behavior that wasn't meant to happen. When using a time turner like Harry and Hermione did, so close to their past selves it's important for them to keep in mind what did happen and when. For example when Harry, Ron and Hermione were hiding behind the pumpkins with future Harry and Hermione hiding behind them in the trees. Past Hermione does see herself but smartly cuts herself off before saying it and seems to choose to ignore it. In that moment a lot could've happened that would've messed up the timeline. If future Hermione had been focused at that moment on the "do not be seen" rule she could've panicked and inadvertently messed up the timeline but she was quick to hide herself and Harry better after past Hermione saw her as that is what had already happened. Future Hermione knew she had seen herself but only very briefly and that briefness was important as it's what allowed past Hermione to brush it off.

Now Harry possibly seeing himself is a whole other issue. As Harry states when Hermione asks what he would've done if he himself burst into Hagrid's hut, he would've thought he'd gone mad or that it was dark magic. The important one of those in my opinion is his possible reaction that it was dark magic. Harry being Harry would've most likely attacked something he thinks to be dark magic without too much hesitation and therefore he could've hurt, if not killed, his future self. However technically Harry does see his future self that night and even though it isn't a direct view of himself he does basically react in the "thinking he'd gone mad way". Harry sees himself cast what he knows to be his own patronus and without having the knowledge of time turners when first processing the occurrence he believes it to have been his father rather than himself which in Harry's case is not really any more realistic than the thought of it being himself. Since Harry processed the occurrence before knowing about time turners, even after going back in time he is still set on the idea that it was James he saw, not himself, especially as he didn't believe himself capable of casting such a strong patronus. This, to a degree, demonstrates the "gone mad" reaction since Harry truly believes himself to have seen his own long dead father regardless of knowing that to be impossible.

So overall, Hermione's worry is not so much about her seeing herself but rather Harry seeing himself as he didn't know about the time turner beforehand. In addition, I do believe Hermione being Hermione knew that while her past self seeing her wouldn't be as large of an issue as Harry seeing himself, it could be detrimental due to the use of the time turner that night being unplanned and thus knowing her past self seeing her could change the events of the night if her past self saw her and realized something happened to need a trip back in time.

Also I wanted to add to the mention of the 1899 DoM experiment that led to the death of Eloise Mintumble and the confusion on the story's source besides the wiki. The original source for the story is Pottermore and later the Wizarding World website. It can still be found on the Wizarding World website.