Ending Debate *Spoilers*

[Belazor et Britannia]

The problem with the "grandfather paradox" is that you would have to impregnate your grandma to be born. The problem with Rinoa being Ultimecia is that you can't exist in a future once you kill yourself in the past. Now I suppose there could be something that happened when they went into the "time compression" thing where past/present/future were all rolled into one that maybe Rinoa could die and Ultimecia could live.

That's not at all how the multiverse theory / string theory resolves the grandfather paradox, nor has needing to impregnate your own grandmother ever been a part of the grandfather paradox.

The theory of the multiverse (which is enabled by string theory) is that every single time you take an action, a separate universe is formed where you take another action. For instance, if you go to Burger King and ask for a burger, they ask you "do you want fries with that?", and you say yes. By saying yes, another universe pops into existence where you say no.

In other words, every possible thing that could have occurred, has occurred, in an alternate reality.

Now for how that resolves the Grandfather Paradox:
Let's say you are currently living in Universe A. If you travel back in time, you are not travelling back to a point in Universe A. This action created a new universe, Universe B, in which you now exist. Therefore, if you kill your grandfather in Universe B, your birth in Universe A is unaffected.

Therefore, there's no grandfather paradox, and you have no need to impregnate your grandmother. You will never be born in Universe B, but you do not fade out of existence because you originated in Universe A, where your grandparents and parents still meet "on schedule".

As for how this relates to FF8, if Rinoa became Ultimecia in Universe A, the universe you're playing in FF8 would be Universe B. Therefore, if Ultimecia kills Rinoa in Universe B, Ultimecia does not die because she was created in Universe A.

All I'm saying is, the Multiverse Theory means that everything people are saying about "Ultimecia killing Rinoa would also kill Ultimecia if they are the same person" is not necessarily true.

Do you see what I mean now?

 

[Galadín]

Whatever the theory is, it doesn't explain why any future rendition of Rinoa (Ultimecia) would want to kill herself.

 

[Belazor et Britannia]

I've not really read up on these theories (I read the SID theory years ago), but couldn't Ultimecia wanting to kill herself and her beloved be explained by her losing her mind? If she's so far gone that she wants to destroy time itself, then surely just seeing her younger self would not "snap her out of it" as it were?

Anyway, I'm playing devil's advocate here, as I don't subscribe to that theory nor to the SID theory. I think both of these theories are examples of fans loving a game so much that they spend the time to work out plot elements that can explain what would otherwise be considered plot holes.
Certain things in the story doesn't necessarily make sense: It's all a dream and his fractured mind is conjuring up the images OR the development team as a whole (designers, writers and programmers) didn't have excellent communication during that particular project, so some things were a little bit disjointed.

I think it's fantastic that gamers come up with this stuff, just like I loved reading all of the FF7 "cheats" for reviving Aeris and getting a black Chocobo, and so forth

 

[Miasma Dragon]

Whatever the theory is, it doesn't explain why any future rendition of Rinoa (Ultimecia) would want to kill herself.

It wouldn't be that she wants to kill herself.

The R=U theory is also based on the in-world fact that Guardian Forces cause memory loss every time they're used (they talk about this when you're visiting the Moomba's town after NORG is defeated, though I think you can use the desk at the beginning to find out). So over time, Rinoa loses memory of everything while the world continues instilling in her their hatred of sorceresses (just like in the real world, we usually remember the bad things in life most). So how would she pick the same time era and people from her history? Maybe she knows there's something significant about those names but she just doesn't know why or how they were significant to her. In trying to connect their significance, she comes to believe they're all responsible for her treatment while supposing someone among them wanted to stop them (since Seifer always had the vision of being a white knight, for someone with no memory it'd be easy to trust that anyone opposing said person must be in the wrong, whereas Squall is more gritty about the real world and has no such aspirations, only caring about his little sister).

 

[SquallKefka17]

It wouldn't be that she wants to kill herself.

The R=U theory is also based on the in-world fact that Guardian Forces cause memory loss every time they're used

But the problem with that is FF VIII implies from the outset that Ultimecia is trying to defy her fate of been defeated by SeeD. For that to work out would literally mean selective memory loss on Ultimecia's part that she would remember who is going to travel to the future to defeat her but not who those people are to her makes no sense whatsoever.
Also at the orphanage at end of disc two even though the party members fail to recognise each other they don't lose memory of who they are theirselves.
Ultimecia would still be able to recognise herself surely.

The theory of the multiverse (which is enabled by string theory) is that every single time you take an action, a separate universe is formed where you take another action. For instance, if you go to Burger King and ask for a burger, they ask you "do you want fries with that?", and you say yes. By saying yes, another universe pops into existence where you say no.

In other words, every possible thing that could have occurred, has occurred, in an alternate reality.

Now for how that resolves the Grandfather Paradox:
Let's say you are currently living in Universe A. If you travel back in time, you are not travelling back to a point in Universe A. This action created a new universe, Universe B, in which you now exist. Therefore, if you kill your grandfather in Universe B, your birth in Universe A is unaffected.

Doesn't Time Compression imply that all instances of the universe have become one? That all possible alternate multiverses have now been fused into one.
Therefore the final Rinoa appearing in front of Ultimecia at Ultimecia castle if Ultimecia defeats her then she is defeating herself.
There are no possible alternate instances left at that point as Universes A, B and so forth cannot exist anymore due to her own magic.
And also how would Ultimecia know which instance of the universe she is in when travelling back in time?
Odine's machine would have to be able to traverse multiverses as well as time for that to be possible which the game doesn't hint at.