(ORDO NEWS) — Decades ago, a conjecture called superdeterminism is a response to several features of quantum mechanics: the apparent randomness of quantum events; their apparent dependence on human observation or measurement; and the apparent ability of a measurement in one place to instantly determine the result of a measurement elsewhere, an effect called non-locality.
Einstein, who called nonlocality “spooky action at a distance”, insisted that quantum mechanics must be incomplete; there must be hidden variables that the theory overlooks.
Superdeterminism is a radical hidden variable theory proposed by physicist John Bell. He became famous for the 1964 theorem, now named after him, which sharply exposes the nonlocality of quantum mechanics.
Bell said in an interview with the BBC in 1985 that the riddle of nonlocality disappears if one assumes that “the world is superdetermined, with not only inanimate nature working behind the scenes clockwork, but also our behavior, including our belief that we are free to choose one experiment, and not another, is absolutely predetermined.”
In a recent video, physicist Sabine Hossenfelder, whose work I admire, points out that superdeterminism eliminates the seeming randomness of quantum mechanics. “In quantum mechanics,” she explains, “we can only predict the probabilities of measurements, not the measurements themselves. Outcomes are undefined, so quantum mechanics is indeterministic. Superdeterminism brings us back to determinism.”
“The reason we can’t predict the outcome of a quantum measurement,” she explains, “is that we don’t have enough information, that is, hidden variables.” Superdeterminism, she notes, gets rid of the problem of measurement and nonlocality, as well as randomness.
Hidden variables predetermine how physicists will conduct experiments; physicists may think they are choosing one option over the other, but they are not. Hossenfelder calls free will “logically incoherent nonsense.”
Hossenfelder predicts that physicists will be able to confirm superdeterminism experimentally. “At some point,” she says, “it will become apparent that the results of measurements are actually much more predictable than quantum mechanics claims.
Indeed, perhaps someone already has the data, they just haven’t analyzed it in the right way.” . Hossenfelder defends superdeterminism in more detail in a technical paper written with physicist Tim Palmer.
Hossenfelder’s commitment to determinism puts her in good company. Einstein also believed that specific causes must have specific, non-random effects, and he doubted the existence of free will. He once wrote: “If the Moon, making her eternal journey around the Earth, were endowed with self-consciousness, she would be deeply convinced that she goes her way of her own free will.”
However, I am puzzled by superdeterminism, whether it is expounded by Hossenfelder or another prominent proponent, Nobel laureate Gerard t’Hooft. When I read their arguments, I feel like I’m missing something.
The arguments seem to be circular: the world is deterministic, therefore quantum mechanics must be deterministic. Superdeterminism does not define what the hidden variables of quantum mechanics are; it simply states that they exist and that they determine everything that happens, including my decision to write these words and your decision to read them.
Hossenfelder and I argued about free will in a conversation last summer. I pointed out that we both made the choice to talk to each other; our choices are driven by “higher-level” psychological factors, such as our values and desires, which underlie but are not reducible to physics. Physics cannot explain choice and therefore free will. That’s why I said.
Invoking psychological causes “will not make the laws of physics disappear,” Hossenfelder told me sternly. “Everything is physics. You are made of particles.” I felt that we were talking past each other. For her, the non-deterministic world does not make sense. For me, a world without choice is meaningless.
Other physicists insist that physics provides enough room for free will. George Ellis advocates “downward causality”, which means that physical processes can lead to “emergent” phenomena, in particular human desires and intentions, which in turn can influence our physical selves.
Mathematicians John Conway and Simon Kochen go even further in their 2009 paper The Strong Free Will Theorem. They make a mathematical argument, reminiscent of John Bell’s quantum nonlocality theorem, that we have free will because particles have free will.
In my opinion, the debate about whether physics excludes or allows free will is debatable. It’s like invoking quantum theory in an argument about whether the Beatles are the best rock band in the world (which they certainly are).
Philosophers speak of an “explanatory gap” between physical theories about consciousness and consciousness itself. First, this gap is so great that it can be called an abyss. Secondly, this abyss applies not only to consciousness, but to the whole sphere of human affairs.
Physics, which tracks changes in matter and energy, cannot say anything about love, desire, fear, hatred, justice, beauty, morality, meaning. All these things, viewed in the light of physics, can be called “logically incoherent nonsense”, as Hossenfelder put it. But they have consequences; they change the world.
Physics as a whole, and not just quantum mechanics, is clearly incomplete. As the philosopher Christian List recently told me, people are “not just a bunch of interacting particles.” We are “deliberate agents with psychological properties and mental states” and the ability to make choices. Physicists recognize the limitations of their discipline.
Nobel laureate Philip Anderson argues in his 1972 essay “More is Different” that as phenomena become more complex, they require new ways of explaining; even chemistry is not reducible to physics, let alone psychology.
Bell, the inventor of superdeterminism, obviously didn’t like it. He seems to have viewed superdeterminism as an absurd proposition (reductio ad absurdum) that emphasizes the strangeness of quantum mechanics. He was not crazy about any interpretation of quantum mechanics, once calling them “like a literary fiction”.
Why does the debate about free will and superdeterminism matter? Because ideas matter. At this time in human history, many of us already feel helpless, at the mercy of forces beyond our control. The last thing we need is a theory that reinforces our fatalism.
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