Sunday, April 17, 2005

Thoughts on Free Will

If all particles in the universe are influenced in predictable ways by the same physical forces then it should be possible to determine the future from any given time because you could just compute where all the particles in question will be after a certain amount of time. From this argument we see that all life has been predetermined and that the future is not of our making but the mearly the logical progression of particles under the influence of the physical forces, right? Stephen Hawking, in his book A Brief History of Time, takes this stand point. But, he brought up the idea that an organism as complicated as humans is still not capable of computing the amount of data necessary to predict the future of anything larger than just a few atoms for a very short period of time in an isolated environment and even that is extremely difficult. So, if we can not predict the future, eventhough it is theoretically possible, then our actions can still be considered free will because unless you already know what the next step is you are still faced with making a decision and no one else will know for certain what the result of that decision will be. So until a computer is invented that can acurately predict the motions and interactions of all the particles in the universe then humans can still consider their choices that of free will.

Another topic that Stephen Hawking didn't really talk about is that of the Heisnberg Uncertainty Principle that states that the more precise the position of a particle is known the less you can know about its momentum. Heisenberg came up with the mathematical proofs for his Uncertainty Principle in 1927 and from that was born todays definition of quantum mechanics. Basically how this relates to the free will discussion is that even if you had a super computer it would have to make a yes or no choice at some point that would decide where that particle is exactly located and that is not entirely possible. It could give each particle a high probability of being in a specific place at a specific time and then make calculations based off of the highest probability but in the real world there is still a slight probability that the particle will be somewhere else at a different time and that makes computing all the possibilities impossible because there are an infinite number of possibilities.


RC said...

It is not as easy as that, I'm afraid. As I understand, the Heisenberg principle of uncertainty doesn't belong to the mathematical theory behind the quantum mechanics. It's just one way of interpreting what the mathematical model says. Especially what it says about measuring (of speed, momentum, position, and so on...). So it is highly unclear whether you can use the Uncertainty Principle in a context where you try to explain problems of the free will.

But there are other arguments to counter the idea that everything is theoretically computable. I think the idea is based on a very small part of our daily existence. Only in a laboratory, the circumstances are ideal to compute which consequences will follow out of the original setting. And even then the computation is not ideal. That's why there is an error margin in science.

And as we can see in Chaos Theory, there are events which are even theoretically not computational. In standard physics time has no influence. E.g. an apple which falls from a tree. You can compute the postion and speed of the apple during his fall from tree to ground, or backwards, from ground to tree, as if the apple would jump back to the tree. Now Chaos theory states that there are facts/events in our world which cannot be computed in both ways (chronologically and backwards-chronologically). Famous example: pourring milk in a cup of coffee and stirring. It is impossible to "unstir" the milk, to undo the process of mixing the milk and the coffee.

(I'm sorry, but I'm not a native English speaker. I hope the general idea behind my text is clear.)

Nagaraj said...

The problem of free will is very tricky. If we do not have free will, we will never be able to tell whether or not we have free will!

I still havent been able to find any comprehensive answer to this. But one thing is for sure that we all "want" to have free will!