Free will

1. Jun 10, 2015

black hole 123

this is probably not appropriate but i dont know where to ask. if classical physics was correct then everything would be predestined and we have no free will. quantum physics merely added "randomness" to it, our thoughts are not chaotic and random. can someone explain how this randomness can give rise to ordered thoughts and "free will"? i dont want to get into religious debates here...

2. Jun 11, 2015

Simon Bridge

Trying to avoid too much philosophy - it is not so clear cut and there is lots of stuff written on the subject - including these accessible resources:
http://www.scientificamerican.com/article/quantum-physics-free-will/

In a nutshell - the forward path in QM is no longer deterministic.
This leads some people to think that some act of will may influence the probabilities.
However - a proper treatment requires a solution to the mind-body problem.

3. Jun 11, 2015

Demystifier

Classical and quantum laws cannot explain a true free will. Yet, they can explain an illusion of free will. For this, one probably needs a complex system in a regime somewhere on the boundary between chaos and order.

4. Jun 11, 2015

kith

A certain amount of free will is necessary in order to do science. If an observer cannot chose what measurements he makes, he cannot trust that he infers the correct laws.

In the context of QM, the idea that the observer may not have free will goes by the term superdeterminism. But as I wrote, it affects all of science (see also the Zeilinger quote at the end of the wikipedia article).

Last edited: Jun 11, 2015
5. Jun 11, 2015

bhobba

First you need to understand what QM actually says. Although not usually pointed in discussions of QM, where they often tacitly assume its in some sense fundamentally random, in fact the theory is silent on it because we have interpretations that are deterministic like BM.

So the free will issue is exactly the same as it always was - which is as Demystifier said - true free will is a rather difficult issue - the illusion of it though can be explained.

Its an interesting issue, but it's a philosophical one, and not really science.

Thanks
Bill

6. Jun 11, 2015

ddd123

Try Penrose's work.

7. Jun 11, 2015

stevendaryl

Staff Emeritus
I just wanted to point out that the phrase "free will" comes up in discussions of Bell's theorem (which is a proof that quantum mechanics implies correlations between distant measurements that cannot be realized using classical, non-quantum, means without violating Special Relativity). There, it isn't really a philosophical condition, and doesn't necessarily have to do with conscious human beings at all. Instead, it's a kind of independence assumption.

In an EPR type experiment, you have two distant experimenters, Alice and Bob. Each of them has a device that has a number of possible settings. A pair of particles is created at some location between Alice and Bob, and one particle is sent to each of the experimenters, who then perform a measurement using the device with the chosen device settings. The free will assumption amounts to something along the lines of:

For any property $\lambda$ of the twin pairs at the time of their creation, and for any pair of settings $\alpha$ (Alice's setting) and $\beta$ (Bob's setting), there is a possible run of the experiment in which the twin pairs have value $\lambda$ and Alice's setting is $\alpha$ and Bob's setting is $\beta$.​

So it doesn't actually involve Alice or Bob's "free will". What this assumption rules out is the possibility that the choice of $\lambda$ constrains the possible values of $\alpha$ or $\beta$. The free will assumption seems pretty innocuous in this limited form. If Alice and Bob use some kind of random number generator to decide what setting to use, then that would satisfy the "free will" condition without saying anything about the nature of human consciousness--a robot can use a random number generator as well as a human can. If the free will assumption is false, then it implies that, in a sense, there are no random number generators, that any two supposedly random number generators produce results that are correlated in a specific way.

8. Jun 11, 2015

stevendaryl

Staff Emeritus
The denial of free will in the context of discussions of Bell's theorem involves more than just saying that nothing is truly random. Instead of using a random-number generator, an experimenter could base his decision on some astronomical fact: Alice points a telescope toward some region of the sky, and counts the number of stars in her field of vision, and makes her decision based on that number. So for Alice's setting to be predetermined, it would be necessary for the entire universe to be arranged so as to force Alice to make a particular choice. That's not impossible, but it's very strange. So usually people assume free will in the sense of Bell's theorem, without meaning anything too philosophical about the nature of "free will".

9. Jun 11, 2015