I feel its super clear if you read the story before the movie existed. Also the physics examples, which aren't in the movie, make this clear.
There are two views of the world, in one you have freewill and experience making choices. In the other, you have no free will, and the things you do are set. They are set and you know what they are.
That's why its important that her daughter died of something preventable, so when you find out at the end that it hasn't happen yet, yet she does nothing to stop it even though it is in the future, you are getting a taste of seeing the world in this second way.
Cancer, there is nothing anyone can do, and it throws aside the whole premise.
The acting on seeing things in the future break the premise as well.
The point of the story was that you can't act on the future. If you can see the future you can't change it. It's also why the aliens had no strong reason for coming or leaving. They were always going to come, have the explosion and leave.
There are two views of the world, in one you have freewill and experience making choices. In the other, you have no free will, and the things you do are set. They are set and you know what they are.
That's why its important that her daughter died of something preventable, so when you find out at the end that it hasn't happen yet, yet she does nothing to stop it even though it is in the future, you are getting a taste of seeing the world in this second way.
Cancer, there is nothing anyone can do, and it throws aside the whole premise.
The acting on seeing things in the future break the premise as well.
The point of the story was that you can't act on the future. If you can see the future you can't change it. It's also why the aliens had no strong reason for coming or leaving. They were always going to come, have the explosion and leave.