Recently I read a book called Pastwatch.  It is a Sci-Fi book.  It was about the future generation that is left to rebuild the world after exploitation of the past generations.
They invented these machines to educate them on the past.  I think they were like computers.  The technology gave them the ability to pick any moment in time and go back and watch a person or people lives in detailed.   It was to educate these people on the mistakes and accomplishments of the past.  The current world that they live in could not be repaired as thought and they were all going to perish due to famine.  So they got to pick a time in history to go back and alter, so that there could be a future for many generations beyond theirs.  The era of choice was the later 1400’s and person they choose to alter was Christopher Columbus.
The concept was interesting, if you could choose a time or person in history to alter, what would you choose?
For me, I would just choose to alter a decision my mother made around 1974. No, I think I would alter my father to be more demonstrative with his love.  I think that would have changed all of our lives for the better. Isn’t it funny how something so small as affection/love could alter the outcome of the future?