I am a fan of science fiction. I like imagining what the future will be like. One sub-species of the genre I don’t like is time travel stories. Time travel seems like cheating — you can’t go back in time and fix where you messed up. That is the lesson from the Book of Ecclesiastes. There is an appointed time for everything, and a time for every thing under the heavens. That tells us that what we do with our time matters. The decisions that we make, the actions we perform, the relationships we enter into are etched in time. There is no re-do. For example, we can’t undo the harm we have done to the environment but the decisions we make today determine the future.