Explanation on the R=U theory?

[Sir Bahamut]

For a full breakdown on the R=U theory, please read the R=U section of the "Time/Ultimecia Plot FAQ" found here:

http://www.gamefaqs.com/console/psx/game/197343.html

Lilliputian Hitcher gave a good summary of the situation, but if you want to know exactly what arguments were used on both sides and such specific details, check out the FAQ.