The Quantum Enigma: Finding the Hidden Key
by Wolfgang Smith (1995)
Smith makes one of the more promising attempts to connect classical metaphysics to modern physics. Interestingly, he thinks this reconciliation is easier in quantum than Newtonian physics, the latter being too inhospitably Cartesian. Quantum mechanics is famously weird. First, there is the issue of noncommuting operators. Thus, for instance, if my spin 1/2 particle is in a definite z-axis spin state, it cannot be in a definite x-axis spin state. A particle being in a definite superposition of eigenstates with respect to at least some observables is inescapable. Second, there is the “measurement problem”, that if I do measure the x-axis spin, the state vector will “jump” to one eigenstate or the other, and state vector collapse is nondeterministic, nonlocal, and not obviously consistent with the Schroedinger equation. Regardless of your philosophical commitments, at least one of the above features is probably horrifying to you. Smith thinks it’s just our false modernist beliefs that make this seem troubling. He claims that in quantum superposition, we have rediscovered the Aristotelian principle of potency (a suggestion, he notes, also made by Heisenberg), and in state vector collapse we are witnessing “vertical” (i.e. formal) causation.
The early chapters hinge on a distinction Smith draws between the “corporeal” world that we directly perceive and the “physical” world that we measure. This is reminiscent of the Cartesian/Lockean distinction between subjective, qualitative features and objective, geometrical features of the world, except Smith emphatically locates them both outside our minds yet maintains that they point to real, ontologically distinct aspects of objects. I admit that I found this discussion difficult to follow, but “primary”/”secondary” quality distinctions have always confused me, and Smith would probably say that I shouldn’t understand what early modern philosophers wrote about them.
Things became much clearer for me in the last chapter. As I understand it, Smith’s case is as follows. Quantum particles being indeterminate (in some observables) allows them to act as a material principle (in the Aristotelian as well as modernist sense) that receives determination from its formal principle when incorporated–literally–into a corporeal being. The distinguishing feature of being a corporeal object is not being macroscopic, but having a substantial form. Substances (in the Aristotelian sense) have forms and are not subject to quantum superposition–they are the Copenhagen interpretation’s classical measuring devices. A particle being incorporated into a corporeal object (e.g. by affecting the state of a corporeal measuring device) collapses its wavefunction, at least with respect to those observables that affect the substance’s corporeal state.
This is certainly an elegant move–Aristotelians are looking for a way to find formal causes in modern physics, while physicists are looking for a way to understand a type of causality that at least appears very different from the usual deterministic Schroedinger evolution, and lo, the two needs can be made to answer each other nicely. Whether it works in detail would be a wonderful topic for further thought; this would no doubt have to deal with the usual Scholastic difficulty of identifying what qualify as substances (“corporeal” objects), but that would be an excellent project for Scholastics looking to re-engage with the corporeal world.
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Throne and Altar 
WOW just what I was searching for. Came here by searching for erratum musical
Just so I understand correctly, this would involve the claim that (at some level) quantum interactions function differently inside living things than otherwise?
Smith would claim that “corporeal” objects (i.e. material substances) are a broader category than living beings. For his scheme to work, ordinary measuring devices would also have to qualify. It’s true in my opinion that substantial forms are not as easily identified for inanimate beings (something the Scholastics have never forgiven Descartes for noticing), but this problem is no worse than it was before, and added incentive has been given for solving it.
>Whether it works in detail would be a wonderful topic for further thought; this would no doubt have to deal with the usual Scholastic difficulty of identifying what qualify as substances (“corporeal” objects), but that would be an excellent project for Scholastics looking to re-engage with the corporeal world.
I don’t think neo-Thomists typically understand what a horrible quagmire hylomorphism was. Or I should say, the cottage industry of Jesuits writing books on esse and essentia understands the historical dispute between Thomas and his rivals perfectly well, but not why the Thomist position permanently excludes Aristotelianism from scientific coherence; whereas the mere enthusiasts have sharp intuitions about how hylomorphism could fit into modern science, but have no idea that they are reinventing a position from approximately 800 AD which led to centuries of semi-incoherent quaestiones.
Quick physics question, Bonald – there’s a story making the rounds today about a collision between two neutron stars which was observed creating a gamma ray burst and ejecting heavy elements. How exactly does that happen? My understanding was that individual neutron stars are only kept from collapsing by neutron degeneracy pressure, and that a collision between them would more or less immediately create a singularity that nothing could escape from. Is matter and energy just getting flung out faster than the collapse occurs?
Numerical simulations (of the sort I do) suggest that when two neutron stars merge, they will promptly collapse to a black hole only if the total mass of the binary is above a certain threshold. (I can’t give you a number, because it depends on unknown properties of high-density nuclear matter.) The remnant is held up by some combination of degeneracy pressure, thermal pressure, and centrifugal force. If the latter two are necessary to hold the neutron star up, then it will collapse to a black hole after a delay given by the time it takes the remnant to spin down by gravitational waves, or redistribute angular momentum by turbulence, or cool by neutrino radiation, or spin down by pulsar emission. Even when the star collapses, some material in its outer regions may have enough angular momentum to form a disk around the newly-formed black hole. There are several ways matter can be ejected, after which it will undergo nucleosynthesis and glow. It can be ejected from the outer end of a less compact neutron star as it tidally disrupts, it can be flung from the collision point along the poles, or it could come from a wind blown off the post-collapse accretion disk.