Sabine Hossenfelder delivers a provocative takedown of a foundational assumption in modern physics, arguing that the field's rejection of superdeterminism stems not from mathematical rigor but from a philosophical fear of losing free will. This piece is notable because it strips away the mystique of "spooky action at a distance" to reveal a nomenclature problem that has misled physicists for decades. For the busy professional seeking clarity on quantum mechanics, Hossenfelder offers a rare path that restores logical consistency without requiring magic.
The Free Will Trap
Hossenfelder begins by dismantling the very name of the theory it defends. She notes that "superdeterminism is a terrible nomenclature because it suggests something more deterministic than deterministic," when in reality, it is simply as deterministic as Newton's laws. The core of her argument is that the scientific community has conflated a mathematical condition with a philosophical stance. As she puts it, "Bell proved that a hidden variables Theory which is a local and B fulfills an obscure assumption called statistical Independence must obey an inequality." The violation of this inequality in experiments led many to believe that local realism was dead, but Hossenfelder insists the real culprit was the unexamined assumption of statistical independence.
She traces this error back to John Bell himself, who, in an attempt to convince physicists to accept non-locality, framed the alternative as the total loss of human agency. Hossenfelder writes, "Bell called a violation of statistical Independence super determinism and claimed it would require giving up free will." This framing was a rhetorical trap that the physics community walked right into. The author argues that this was bad science, stating, "throwing out determinism just because you don't like its consequences is really bad science." By accepting Bell's binary choice, physicists abandoned a logical possibility to preserve a comforting illusion of autonomy.
The alleged strangeness of quantum mechanics has its origin in nomenclature, forced on us by physicists who called a mathematical statement the Free Will assumption.
Critics might argue that abandoning statistical independence undermines the very basis of experimental science, but Hossenfelder counters that this fear is misplaced. She points out that the majority of philosophers do not share the physicists' anxiety, noting that "about 60% of them believe that Free Will is compatible with determinism or they agree with me that Free Will doesn't exist anyway." The resistance to superdeterminism, she suggests, is an emotional reaction rather than a scientific one.
The Mechanics of Measurement
Moving from philosophy to physics, Hossenfelder uses the double-slit experiment to illustrate how superdeterminism actually functions without destroying reality. She explains that in standard quantum mechanics, measuring which slit a particle passes through collapses the wave function, destroying the interference pattern. This collapse is often described as "spooky action at a distance," where the particle seems to know instantly that it is being observed. Hossenfelder reframes this: "what the quantum particle does depends on what measurement will take place."
In this view, the particle's behavior is not random or non-local; it is pre-determined by the hidden variables that correlate with the experimental setup. She clarifies that this does not mean the experimenter lacks choice. "The experimentalist can measure whatever they like," she writes, "it's just that what the particle does depends on what they measure." This distinction is crucial. The correlation exists between the hidden state of the particle and the detector setting, not between the particle and the experimenter's conscious intent.
She addresses the concern that this would make randomized control trials impossible, such as in vaccine testing. Hossenfelder dismisses this as a category error: "believing that super determinism plays a role for vaccine trials is like believing Schrödinger's cat is really dead and alive." The correlations required for superdeterminism only manifest in specific quantum scenarios where non-locality would otherwise be required. Once a measurement occurs, the system decoheres, and the macroscopic world proceeds as expected. "That's why we don't see dead and alive cats because there's always some environment like air or the cosmic microwave background," she explains.
Restoring Scientific Integrity
The final thrust of Hossenfelder's commentary is that superdeterminism is not a conspiracy theory but a legitimate, albeit unpopular, solution to the measurement problem. She criticizes prominent physicists for dismissing the idea without rigorous engagement. She cites Nicolas Gisin, who claims that without free will, "there could be no rational thought," and Anton Zeilinger, who argues that the "freedom of the experimentalist" is essential for science. Hossenfelder finds these arguments circular and unscientific. She writes, "we have no shortage of men who have strong opinions about things they know very little about."
By rejecting the "Free Will assumption," the physics community has forced itself to accept non-locality—a phenomenon that defies the speed of light limit—or to accept that the wave function collapse is merely an update of information. Hossenfelder argues that superdeterminism offers a third way that respects locality and determinism. "Superdeterminism takes our observations seriously," she asserts, suggesting that the universe is consistent and predictable, even if it is not random in the way we prefer.
If you find this hard to believe, I can't blame you, but let me read you a quote from a book by Nicolas Gisin... for me the situation is very clear not only does Free Will exist but it is a prerequisite for science.
This section highlights the author's frustration with the dogma that has taken root. She suggests that the fear of superdeterminism is a barrier to understanding the true nature of quantum mechanics. The argument is compelling because it shifts the burden of proof back onto those who claim that randomness is fundamental, challenging them to explain why a deterministic universe is any less scientific.
Bottom Line
Sabine Hossenfelder's strongest move is exposing the "Free Will assumption" as a non-scientific bias that has distorted the interpretation of quantum mechanics for decades. Her biggest vulnerability is the difficulty of empirically distinguishing superdeterminism from standard quantum mechanics, a hurdle she acknowledges but does not fully resolve. Readers should watch for how this argument influences the next generation of quantum experiments, particularly those designed to close the "freedom-of-choice" loophole.