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The case against free will
Laplace’s demon is a little character that occasionally pops up in the history of physics. Pierre-Simon Laplace wrote about it in 1814 to describe the deterministic nature of our universe. Imagine a sneaky demon, who somehow knows the position and momentum of every particle in the universe. This demon will be able to know exactly what the universe did at some earlier time and, more importantly, precisely what it’ll do at some later point. In other words, with perfect knowledge of the current state of the universe, it can determine what will happen at any point in the future.
The notion that our universe is deterministic is an intuitive one. When you throw something or hit a snooker ball, they follow a predictable path. Since Galileo and Newton, we know that all that’s needed to predict how a physical system will behave is some measurements and some calculations. It’s how we discovered Neptune and the reason we can predict with such accuracy when the moon will cross between us and the sun to produce a solar eclipse. Determinism tells us that Mars isn’t going to start going backwards, throwing off the probes that are en route and Voyager 1 won’t just give up one day and decide to come home.
However, the fact that matter in this universe doesn’t decide to do things is a problem because we are matter, and we regularly appear to make decisions.
