Free Will and Quantum Mechanics

*^{_{Before beginning this article, you might want to read this to have a better overview. https://themarinewsblitz.com/2022/03/about-the-utility-of-advanced-physicsquantum-computers/}}

Suppose you are a philosophy student of the early 1810s in France. You are particularly interested in notions of libertarianism, a political philosophy that, as the name suggests, centers around human liberty. In libertarianism, you have seen that freedom of choice is vital in society as it permits every individual being to choose which course of action to take under particular circumstances and to be held accountable for it.

 This notion of free will seems to you not only very reasonable, but also extremely verifiable; all your life, you have been able to make choices, you have acted of your own resolve, and you haven’t felt that anything, or anyone, control your decisions.

You have, however, heard of people who don’t believe in this free will. Notably, you are aware of the theological argument, the supposition that there is a higher being or beings that either has already planned history as a whole, and you are merely following the path they created for you, or that know everything, controlling your actions accordingly.

These scenarios are plausible in the sense that they cannot be proven wrong, but you are more of an I’ll-believe-it-when-I-see-it type of person, and you have the healthy habit of not believing a supposition simply because there is no counterproof. As such, you reject such a hypothesis and stick to your empirical definition of choice. Perhaps you even reject the idea of a higher being entirely.

​Anyways, you happen to come across recently published Pierre-Simon de Laplace’s A Philosophical Essay on Probabilities. You don’t realize it yet, but you’ve picked up the essay that will model the scientific community for years to come. Laplace, a French scholar known for his contributions to astronomy and math, describes in it a scenario known as ‘Laplace’s Demon’: the ‘demon’ is an intellect that knows not only all the forces of nature but also every particle’s position and momentum at any given moment in time. Laplace believed that such a being could reconstruct the past just as it could predict the future, using only the laws of physics.

Causal Determinism

​While many intellectual minds had already discussed this notion of determinism by that time, Laplace became a symbol for the people who believed in an ideal scientific model of the world, one that could be described entirely by its cause-and-effect relations. For instance, why did an apple fall on Newton’s head? Well, because of its increasing weight pulling on the branch it was growing on. In turn, its growth was only possible because of rain or someone watering the apple tree, which was planted years ago possibly by the wind spreading the seed, an animal defecating the seed there or someone manually planting it, and so on, and so forth.

It makes you wonder if, in a scenario where the apple grew on another branch and fell unnoticed by Newt, he would have thought about gravity. Well, determinism is the idea that it could not have happened any other way. All past events in the Universe happened in a way that led to that precise moment, just as they did for every other moment in the history of the Universe since the Big Bang.

In this sense, how responsible was Newton for discovering the laws of gravity, if his actions, much like all of ours, were already predetermined to happen?

If he isn’t, then who is? Is anyone?

More on Free Will

Responsibility stems from choice; but “hard” determinism rules out the existence of choice, classifying every action as the consequence of all previous actions. So, according to determinism, no one can be responsible for anything, as everything played out the only way it could, effectively annihilating any notion of morality or justice. On the other hand, “soft” determinism is a modified psychological theory of determinism that would include yet limit our free will; for example, we would be able to make our own choices, but there would be a limited number of choices available to us, predetermined by past events.

And so, over time, some started to believe everything in the world was predetermined, and some didn’t. The major counterargument resided in the complexity of some systems of equations. Notably, to this day, the brain is a system that we do not completely understand, and consequently, consciousness is a phenomenon that we cannot yet fully explain through the laws of physics. But determinism isn’t a theory that generates answers and theorems. It simply states that they exist. And so, it persists.

Quantum Indeterminacy

Enter the 20th century, where the exponential advancement of particle physics laid the groundwork for a new branch of physics, quantum mechanics. Soon enough, the scientific world sees its ideal cause-and-effect model crumble at the hands of Max Born, who, in 1926, suggested that particles do not have a precise location but are rather best spatially described by probabilities. This would mean that, at an infinitesimal scale, if you would try to measure a particle’s position, you’d have a certain chance of seeing it here, another of seeing it there, and yet another of seeing it all the way over there, etc… These measurements could thus not be fully described by the laws of physics, since, to a certain extent, their results would be random, and could change with each trial. This is referred to as quantum indeterminacy.

Yes, these measurements would be unpredictable. Not random in the way a random number generator is “random”, since these are programmed to output a seemingly arbitrary number, yet they are still determined. Not random in the way a coin flip is “random” since factors such as speed, angle, the positioning of the hand, air density, and the mass and the shape of the coin (there might be a few more) can fully describe the system and its outcome. Certain physics at a very small scale would be indeed dependent on just pure chance, with no way to tell the outcome of measurement even with all the initial conditions.

Another example of quantum indeterminacy resides in superposition. When a quantum system is in a superposition of many states (as described in my previous article, see About the Utility of Advanced Physics: Quantum Computers), upon measurement (collapse of the wave function), the system will only seem to be in one single state. This state could be any of the states it was previously in, and the measurement of each different state can only be described with probabilities. Initial conditions may affect these probabilities, yet fundamentally, the outcome of this measurement is random.

So, with this information, you’d think hard determinism is pretty much debunked. There would be no way to reconstruct the whole past and future from our present state using only laws of physics since, at a very small scale, sheer randomness would have a very big impact on the very building blocks of our reality. Determinism could not be, and the notion of free will, of humans having any impact or choice in their condition, could perhaps be saved.

Non-Locality

Unfortunately, a few years later, in 1935, Einstein, Podolsky, and Rosen’s Can Quantum Mechanical Description of Physical Reality Be Considered Complete? introduced the concept of entanglement (also described in my previous article). Basically, entangled particles share a common quantum state (which can be a superposition of other states), and so measuring one of the particles’ states (remember, the outcome is a random state among the ones creating the initial superposition of states) gives us direct information of the state of the other particle. In fact, measuring one of the particles makes all the entangled particles collapse into a single, common state, no matter the distance between them.

So, how does this affect determinism? Well, since it was previously established that the outcome of measuring the state of a particle was random, how can we explain two particles or more having the exact same outcome, every single time, at very large distances? This would imply that they “communicate” with each other, perhaps by some intermediary particle; however, this particle would need to travel faster than light, which, in accordance with Einstein’s relativity, is impossible. Quantum entanglement is a phenomenon that has been proven true but that can still not be explained. Dubbed non-locality, the concept that such particles could “share information” faster than light baffles many scientists to this day. To others, however, it implies the existence of “hidden variables” that would determine the outcome of these measurements way ahead of time. Superdeterminism, as it was called, is a theory that could completely cut out randomness from quantum mechanics.

Superdeterminism (hidden variables)

Firstly, I would like to clarify that hidden variables are unmeasurable hypothetical entities used to describe quantum mechanical phenomena in a deterministic way, while superdeterminism formally refers to a loophole in Bell’s (Inequality) Theorem, which supposedly proves the non-existence of hidden variables. These hidden variables have not yet been discovered, and perhaps they never will be; perhaps they are impossible to detect by us, and perhaps they simply don’t exist.

Hidden variables are simply an argument to render deterministic all the physics of the universe. Much like hard determinism, superdeterminism completely negates the existence of a free will, suggesting that there is something, somewhere and somehow, that can explain all the things that seem “random” to us.

Conclusion

Determinism and free will are concepts that have clashed for supremacy for centuries. From our current knowledge of science, there seems to be no way to prove either of them, and there possibly will never be anyway to do so. As such, I’d recommend not to lose your mind over these philosophical questions. Predetermined or not, the choices you make have an impact on your life, so focus on making the right ones; in the end, living a good and happy life is the only thing that does matter.