So, why does time flow in one direction only, why doesn’t it go the other way? There is nothing in the equations that describe how the universe works that says time has to have an arrow. Typically what is time’s arrow is justified by cause and effect and by the lack of reversibility.
You drop a plate on the floor and it shatters. The plate hitting the floor is the cause of the shattering, the plate falling is the cause of it hitting the floor and a combination of you dropping it and gravity is the cause of it falling. Cause and effect and the idea that it can’t go backwards gives time its direction. The “flowing backwards” part, you know, the plate spontaneously reassembling and jumping up to your hand, in physics is part of entropy. The universe has a tendency to become more random, less structured. It can be reversed in a location by adding energy, but you can’t add anything to the Universe as a whole, so entropy increases, i.e., time marches on.
But what about those bundles of reverse entropy called “humans”?
I put the windows up in my car up because I knew it was going to rain. In that case the effect occurred before the cause. Of course there are periodic things that happen, so we prepare for them, getting ready for the evening or changing out our sweaters for shorts because summer is on the way. And there’s non-periodic things. I’m putting money aside for retirement, I pay a lot of money in Insurance in case I have an accident, etc.: these are examples of doing something to prepare for a future that has little to do with our daily lives, a future perhaps decades away. It isn’t like seeing storm clouds on the horizon (or splotches on a weather map). It is totally abstract and has no reality at this time, yet I still act on it.
More than that, our actions can affect the future. This goes back to the time arrow we are used to in many ways, that we do an action that causes things to happen, but it goes beyond it in that we can see that future and predict what our actions will do, what the effect will be.
Animals do it too. Some put nuts away for the winter. Some move long distance to be where they will find food or mates, food and mates that aren’t in those locations when they leave for them.
Do stars or planets change before something is going to happen?
Knowing the future is important in art.
When I wrote classical music I often foreshadowed what was to come. I might play snippets of a theme as part of the background off and on so when the theme appears it isn’t like it was created from this air, it was there in the background all along. Even though a listener doesn’t know the theme, as soon as it appears it seems inevitable, it had to happen that way.
Of course foreshadowing is a huge part of fiction writing. Actually, it is often used in nonfiction, but in fiction we see it all of the time. Foreshadowing can be used to create tension. Something is going to happen in that room, and every time the main character goes there and nothing happens the tension level increases. It can be used to keep the reader’s interests. So, how is the story going to get there from here? It can be used to misdirect. You see how things are going to be, and then something else happens when you looking in the wrong direction. There is also the sense of inevitability that I talked about with the music. You don’t see what’s coming up, but because of the clues when it does happen, it feels exactly right.
Of course in fiction we can also enter the “supernatural” and have things like people being able to predict the future. I was going to say “predict or shape the future”, but do you know what? As stated above, people do shape the future by their actions. I’m going to ignore the supernatural here since it is such a huge topic.
Foreshadowing is also a huge topic. I, of course, just scratched the surface. But knowing the future, occasionally putting the effect before the cause, can add so much to fiction. It is one of the more important tools in a storyteller’s tool-chest.
So, what’s going to happen? Are you going to give a clue without letting the cat out of the bag?