# Free Will Theorem

In today’s VERITAS we will study Conway and Kochen’s Free Will Theorem which attempts to connect Quantum Mechanics and the concept of Free will. Before I explain this in detail, let me state the theorem. The Free Will theorem states that if we have free will then the elementary particles also have a degree of free will.

Now, let me state another theorem on which the Free Will Theorem is based: The Kochen Specker Theorem. The Kochen Specker Theorem states that the values of quantum mechanical variables is not decided before the experiment is done to measure them. So the theorem states that quantum mechanical variables acquire values only when observed. ( Note: This is not the precise definition. This is a simplistic and inaccurate definition).

The Free will theorem is based on three assumptions which have been established by a huge number of experiments:

1) Fin: There is a maximum speed for the propagation of signals from one place to another- this follows from the special theory of relativity.

2) Spin: If you measure the squared spin of a particle along three orthogonal directions you will always get 2 1s and a 0. So you may get (1,1,0) when you measure the spin along x, y and z direction or get (0, 1, 1) or (1,0 1) etc. But you will always get two 1s and a 0.

3) Twin: This assumption states that it is possible to quantum mechanically entangle two particles so that if you measure a certain value of spin in one particle in a direction then you will get the same value of spin when you measure the second particle along the same direction. The two particles can even be light years away and they will still show the same spin value. Such particles are said to be entangled.

The Fin assumption is based on Special Relativity. The Spin and Twin assumptions are based on Quantum Mechanics.

The Free Will Theorem states that if the experimenter is free to choose which experiment to perform( ie measure spin along which direction), then the results of the experiment is equally free. Now let me state what is meant by free here. By free we mean independent of any previous history. So if an experimenter’s choice is independent of any previous history then the results of the measurement of the particle’s spin is also independent of any previous history.

Here is my personal opinion on the theorem: the theorem tries to equate free will with randomness. But can random behavior, even if it is at the most fundamental level, be called free will? Free will has to be a conscious decision and not a random one. If you equate randomness with free will then it is in no way better than determinism as far as fixing moral responsibility is concerned. Does it matter if a murderer says ” I killed because I had no control over my decision- it came from the past states of my neurons”( determinism answer) or says ” I killed because I had no control
over my decision- it came from a random change in my neurons”( free will theorem kind of answer)? The fundamental question still remains: is the person who I call “me” have a “conscious choice” in what to do and what not to do?

regards
Kanwar

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