Everyone knows it is impossible to predict the future, but not a lot of people pause to wonder why. Even putting aside the issue of free choice, it isn’t straightforward. After all, Isaac Newton’s laws of motion can be used to calculate what any object will do if we know its starting trajectory and the forces acting on it. French thinker Pierre-Simon Laplace once imagined a being armed with these laws and a lot of information, writing that “for such an intellect, nothing would be uncertain and the future, just like the past, would be present before its eyes”.
The reason the world still unfolds in a cascade of the unexpected is that there is a gulf between what equations can predict in theory and what it is possible to calculate in practice. The limits of our technology, the speed of our computers and the incredible complexity of nature all mean that some things are practically impossible to know.
This article is part of a special series on the limits of knowledge, in which we explore:
One problem is that the things we want to study are sometimes composed of many objects that mutually affect each other. So while we can predict the path of a flying football just fine, …