The age has come by, and with quantum mechanics (and even classical mechanics) in the picture, both materialism and determinism seem to have come out. Classical mechanics deals with the motion of macroscopic bodies (such tennis balls, planets and asteroids) whereas quantum mechanics deals with the universe at the subatomic level (i.e. what happens at the level of anything smaller than an atom, such as photons and electrons). So, despite the technical names, we all know (or have heard of) a thing or two about these forms of physics, including quantum mechanics, if we’ve ever heard of wave-particle duality (all entities are both waves and particles), nuclear decay (when an atom emits protons/neutrons/photons to become more balanced), wave functions (probability waves) of electrons around an atom, etc. The first book I read introducing me to all these concepts was a well-articulated book by physicist Brian Greene titled The Elegant Universe.
Here, materialism and determinism start becoming problematic. Materialism is the idea that everything that exists has a composition of matter, merely constructed in different modifications, and determinism, the view that everything that will happen is ultimately determined outside of the will, so for example, if you knew everything about every particle in the universe and its movement, size, interaction, etc, you would be able to perfectly predict the future based on inevitable interactions between these particles. These views aren’t synonymous with atheism or naturalism at all, but atheists and naturalists form almost their entire membership, and of course, both concepts contradict supernaturalism (the view that there exists things beyond the natural world) and theism (the view that God/ a god(s) exists). Idealism, certainly, is not a popular view in unbelieving circles.
Determinism, of course, is outright impossible to reconcile with quantum mechanics. According to quantum mechanics, all particles exist in a probabilistic state before being observed/measured. That is to say, the particle/entity literally does not exist in one state as an object, but only exists in a probability region where the particle might be found. This is why things like quantum tunneling occur. In quantum tunneling, a ‘particle’ can pass right through an object (imagine someone walking through a wall) because the wave function it exists as enters the other side of the object by random chance. If this explanation isn’t perfectly clear, this video helps really helps explain the concept.
In other words, in light of the fact that the universe is completely probabilistic, determinism is false, since there is nothing deterministic about the wave function. In fact, it turns out that, according to a 2015 physics paper titled Determinism, independence, and objectivity are incompatible in the journal Physical Review Letters by physicists Radu Ionicioiu, Robert B. Mann, and Daniel R. Terno, determinism is incompatible “not only with quantum mechanics” (from the abstract) but even any classical theory of mechanics. So, the physics community seems to have come to terms with this truth resulting from physics. So why not many atheists?
Materialism falls into the same trap. Matter simply isn’t all that exists, since wave functions exist and are decidedly not matter (also see here). Also, as I was reading some comments by some people on this subject, another simple point was brought up that also does away with materialism, the beginning of the (not just the observable) universe! The fact that matter began to exist is the end of materialism. It’s also important to note that realism, the view that reality exists independently of us, has also been falsified by quantum mechanics (see the book from the renowned physicist Anton Zeilinger’s, Dance of the Photons: From Einstein to Quantum Teleportation). Admittedly, Bohmian mechanics is one way to get out of all this, but it’s probably wrong anyway. Local hidden variable theory has been virtually ruled out by Bell’s inequalities. It’s always nice when physics and science contribute to the slow deconstruction of the unbelieving worldview.