Can quantum mechanics explain how we think?
THE PARADOXES SURROUNDING CONSCIOUSNESS, FREE WILL AND CATS
Thousands of academics gathered in Toronto last week for the annual Congress of the Humanities and Social Sciences, presenting papers on everything from whether poutine is a form of cultural appropriation to Canada’s uncomfortable relationship with nakedness. In its Oh, The Humanities! series, the National Post has showcased some of the most interesting research. Today, Joseph Brean reports.
‘Quantum mechanics” is widely abused as a buzzword by marketers and charlatans, almost to the point of meaninglessness.
The word “quantum” refers to the tiny jumps an electron makes as it increases in energy, the study of which revolutionized science’s understanding of matter and how it works. It has given the world alluring ideas about particles existing in multiple states simultaneously, or communicating with each other instantly over vast distances. But this is only physics, and it has very little to do with skin cream, weight loss, self help, time travel, or mysticism.
There is, however, one attempt to apply quantum mechanics to everyday life that has survived the ridicule — the theory that consciousness itself might be a quantum phenomenon.
Guy Kagan, a philosopher from the University of Haifa, discussed the latest work on this provocative idea at the Congress of the Social Sciences and Humanities in Toronto, where he presented his paper “Wave Function Collapse Theories of Consciousness and Physicalism: The Chalmers-McQueen Model Re-examined.”
The problem is basically this. Physics aims to explain the behaviour of matter with universal laws. Our brains are made of matter. So if consciousness is a product of the brain, physics should be able to explain it with universal laws.
But if physics can explain consciousness the way it explains gravity, this would mean there is no free will, free thought and imagination are illusions, and consciousness cannot play a causal role in the world.
Anybody who has ever decided to do anything, or changed their mind about doing it, can tell you that this conclusion at least seems to be completely absurd.
A key part of this paradox is the assumption that physics is deterministic, that matter behaves according to unchangeable, mathematical laws, so if you knew the current state of the cosmos down to the last atom, you could use the laws of physics to predict the future. Likewise, if you knew the current state of a brain, you could predict all its future thoughts.
But deterministic physics is outdated. The core of quantum mechanics is that there is not much certain at the subatomic level. Everything is more or less potential, probabilistic, at least until you observe and measure it. Then, the various possibilities “collapse,” according to the odds, into this or that determinate state.
The idea that consciousness causes this collapse of quantum possibilities is an old theory in the midst of a revival. It was first expressed in 1939. Later, the Hungarian-American Nobel Laureate Eugene Wigner proposed that nothing ever happens, literally, unless it is measured and observed by a conscious observer. In reflections at the end of his life in 1995, he wrote: “It was not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to consciousness.”
He even devised a thought experiment to illustrate this, a play on the better-known Schrodinger’s Cat, known as Wigner’s Friend.
The Cat experiment was devised by Erwin Schrodinger in the heyday of quantum physics in the 1930s, to illustrate the apparent absurdity of the leading interpretation of this new science, that different states of the same system can somehow exist simultaneously, in “superposition,” until observation made them settle down into one or the other.
Mathematically, this makes perfect sense, and is described by what is now known as Schrodinger’s equation. It has also been observed at the teeny-tiny quantum level. But it seems to lead to some bizarre paradoxes at the larger scale of cats and people. In this case, by inventing a scenario about a quantum measurement connected to a vial of poison, Schrodinger showed that quantum mechanics seemed to say the cat could literally be both alive and dead at the same time.
This made no sense. Something had to give.
Wigner extended this by idea imagining that his friend did the same experiment in his absence, and only told him about it later, raising the question of when the collapse occurred: when the friend observed the cat as either alive or dead, or when Wigner observed the friend as either happy or sad.
Consciousness, somehow, seemed to be at the centre of this baffling physics, just like measurement and observation. Perhaps it could explain how consciousness fits into the world.
Kagan’s work analyzes the recent efforts of David Chalmers and Kelvin McQueen to revive this inquiry. They have argued, for example, that Schrodinger’s equation has terms that “play little role for non-conscious systems, but that cause collapse when there are ‘conscious’ physical structures.”
These structures, the physical aspects of the brain that create consciousness, seem to somehow “refuse superposition and respond with collapse.”
Even if this idea could somehow be proven, another problem would remain. Chalmers, a professor at New York University, is famous for calling it the “hard problem.” He meant that even if you explain every little process of the brain, and show how every last neuron is connected to every other one (these are the “easy” problems), you will still be left with the “hard problem” of how and why this actually feels like something to the thinker.
A computer does not experience its computing. It just does it, blind and stupid as any other machine. A car does not feel itself drive. But a thinker is aware of her own thoughts, how they feel and seem.
Whether quantum mechanics can explain away this problem of consciousness remains in the realm of airy speculation. As ever with fundamental philosophy, there is a long way still to go.
A THINKER IS AWARE OF HER OWN THOUGHTS, HOW THEY FEEL AND SEEM.