How we cite our quotes:
A [Seldon]. Obviously. This courtroom may explode in the next few hours, or it may be. It [sic] it did, the future would undoubtedly be changed in some minor respects. (I.6.44)
Boy, talk about stating the obvious. But even the obvious can be important when understanding time in Foundation. The point Seldon makes here is that not everything is accounted for in the future. Even with his predictions, only the major events have the most possible outcome. The future is still mostly unknown.
Q. (theatrically) Do you realize, Dr. Seldon, that you are speaking of an Empire that has stood for twelve thousand years, through all the vicissitudes of the generations, and which has behind it the good wishes and love of a quadrillion human beings?
A. I am aware both of the present status and the past history of the Empire. Without disrespect, I must claim a far better knowledge of it than any in this room. (I.6.72-73)
What's Seldon saying here? After all, it is his study of the past that has led to his predictions of the future. Does that mean we're all just part of an endless mathematical formula, where past plus present equals future? Is that an unsettling notion—or a comforting one?
"And after you die, sir?"
"Why, there will be successors—perhaps even yourself. And these successors will be able to apply the final touch in the scheme and instigate the revolt on Anacreon at the right time and in the right manner. Thereafter, events may roll unheeded." (I.8.36-37)
As with any future, it's the future generations who will have to do the grunt work of any far-reaching plan. Plan all you want, but it's up to those kids with their Interwebs, Facebook LOLs, and kitteh memes to make the future what it will be.