Corrected entry: Alexander is told he can't change the past because his fiance's death is why he built the time machine. Judging by all the clocks and equations in his home and schoolroom, he might have been working on it anyway. Just seems like a weak paradox.
Grumpy Scot
8th Oct 2003
Correction: Yes he was working on the time machine before her death. However, he wouldn't have been obsessed with it, and as shown to him later, he would have eventually stopped working on it once he had kids.