Free Will, Part 3

In this part of the series I examine whether determinism implies predictability.

In simple deterministic systems, like a ball moving through a vacuum, you could measure the ball with a laser and calculate its future position. You would have to be careful, however, to take the force of the laser measuring device into account! This illustrates a more general problem; if you want to predict a system, the act of observation changes the system which in turn must be factored into your predictions.

In fact, it's even worse that this. Heisenberg's uncertainty principle states that it's theoretically impossible to know the exact position and velocity of a particle at the same time. The more precisely you know one of these values, the less precisely you can know the other.

But wait, it gets even worse! Chaos Theory shows that tiny perturbations in a large dynamic system can trigger a cascade of events that leads to a large system-wide change. The Butterfly Effect movie did a good job of illustrating this. One extreme example of this would be: how different would the world have been if a random cosmic ray had fried the navigation system in Hitler's plane and it had crashed before he started World War II? Even without Heisenberg's uncertainly principle, chaos theory makes large dynamic systems virtually impossible to predict.

So even if the Universe is deterministic, the combination of Heisenberg's uncertainty principle and chaos theory make it theoretically impossible to predict exactly how things will unfold. I will use this fact when analyzing the rest of the question related to Free Will.

Comments

[Just wondering]

What kind of navigation system do you expect was in Hitler's plane that would be sensitive to a "cosmic ray"?

[Kevin Dick]

Hey Graham,

Glad to see you biting off easy topics to analyze :-)

What about the many worlds hypothesis? This makes QM deterministic (and gets rid of the Heisenberg issue), but in a really weird way.

I think it really boils down to the question of emergent phenomena--can one generate unpredictable higher order behavior from deterministic lower order behavior? But I don't want to get ahead of you.

[Graham Glass]

Cosmic rays can be powerful, so anything with an electrical component could theoretically be disrupted by one. Anyhow, it's irrelevant to my point - you could pick anything similar, like a bolt of lightning hitting his plane.

Cheers,
Graham