A lot of the difficulty in understanding quantum physics hinges on the question of free will. We’re confused because it seems that we can decide to measure either the wave properties or particle properties in the same system, and our decision determines whether wave properties or particle properties are seen. But does free will truly exist?
In the classical physics era, when we imagined a strict separation between the observable universe and the people doing the observing, free will was not an issue. The mind was something outside of physics. If we take Newtonian physics to its logical extreme, however, there isn’t really any room for free will. This is because the Newtonian universe is completely deterministic.
The future position and speed of every particle is completely caused by its state at an earlier time, and we can predict that future state just fine using the laws of physics. We are all made of the same stuff as the rest of the universe, and we are all subject to the same physical laws. If physics were completely deterministic, then all of our behavior would also be predetermined. Any perception on our part that we are free to make choices would be an illusion.
Since quantum physics has loosened the strict determinism of classical physics, does this leave room for free will to make a comeback? Some interpreters would say so, but there is a lot of disagreement on this point. There has to be some agent that does the choosing, some aspect of a human being (or other animal) that possesses the capacity to exercise free will. To be able to say anything about how free will works in the context of quantum physics, it needs a scientific definition of that agent, that thing we’ve called a conscious observer. But as of yet we have no good scientific definition of consciousness.
Consciousness seems to be rooted in the brain, and neuroscience tells us that the brain performs many functions based on chemistry and small shifts in electrical potentials. It is a very complex network of interconnected neurons, where the number of connections is on the order of 100 trillion. It is likely that all the features we associate with consciousness—memories, emotions, imagination, and free will—all emerge from the activity of all these interconnected neurons. How that happens, and what role quantum uncertainty might play, are still open questions.
QUANTUM LEAP
The French philosopher Rene Descartes also considered consciousness as fundamental to existence. His seventeenth century statement “I think, therefore I am” was very influential because it provided a secure starting point. Since then philosophers and scientists have mostly agreed that the existence of consciousness is self-evident. I know my consciousness exists because it is the “I” that conceives the question. Beyond that, however, there is very little about the nature of consciousness that we know for certain.
Until we know more about what consciousness is, it will be hard to say anything more definite about whether free will exists or is just an illusion. Right now we don’t know if quantum uncertainty plays a critical role in allowing a conscious being to choose, or if conscious choices have some influence on quantum uncertainty, or both. Only time, perhaps, will tell.
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