Possibly no subject in science has inspired more nonsense than quantum mechanics. Sure, it’s a complicated field of study, with a few truly mysterious facets that are not settled to everyone’s satisfaction after nearly a century of work. At the same time, though, using quantum to mean “we just don’t know” is ridiculous—and simply wrong. Quantum mechanics is the basis for pretty much all our modern technology, from smartphones to fluorescent lights, digital cameras to fiber-optic communications.
If I had to pick a runner-up in the nonsense sweepstakes, it would be human consciousness, another subject with a lot of mysterious aspects. We are made of ordinary matter yet are self-aware, capable of abstractly thinking about ourselves and of recognizing others (including nonhumans) as separate entities with their own needs. As a physicist, I’m fascinated by the notion that our consciousness can imagine realities other than our own: The universe is one way, but we are perfectly happy to think of how it might be otherwise.
I hold degrees in physics and have spent a lot of time learning and teaching quantum mechanics. Nonphysicists seem to have the impression that quantum physics is really esoteric, with those who study it spending their time debating the nature of reality. In truth, most of a quantum mechanics class is lots and lots of math, in the service of using a particle’s quantum state—the bundle of physical properties such as position, energy, spin, and the like—to describe the outcomes of experiments. Sure, there’s some weird stuff and it’s fun to talk about, but quantum mechanics is aimed at being practical (ideally, at least).
Yet the mysterious aspects of quantum physics and consciousness have inspired many people to speculate freely. The worst offenders will even say that because we don’t fully understand either field, they must be related problems. It sounds good at first: We don’t know exactly how some things in quantum physics work, we don’t know exactly how to go from the brain to consciousness, so maybe consciousness is quantum.
The problem with this idea? It’s almost certainly wrong.
Oh, sure: In a sense the brain is quantum, simply because all matter is described by quantum mechanics. However, what people usually mean by quantum isn’t ordinary stuff such as molecules that let brain cells communicate. Instead, the term is usually reserved for the deeper processes that rely on the quantum state. The quantum state is where fun stuff like entanglement lives: the coupling of two widely separated particles that act like parts of a single system. But that level of analysis is not generally helpful for describing the motion of molecules across the gap between cells in the brain.
That’s not to say that quantum effects are entirely ruled out in biology. Some researchers are investigating how photosynthesis or even the human senses of sight and smell might work in part by manipulating quantum states. The retina in the eye is sensitive to small numbers of photons—particles of light—and the quantum state of the photon interacts with the quantum state of the retinal cell. But once those signals are translated into something the brain can process, the original quantum state seems to be irrelevant.
I’ll hedge my bets: Maybe there’s room for some small quantum effects in the brain, but I sincerely doubt those will be directly relevant for consciousness. That’s because almost anything involving individual quantum states requires isolation from environmental interference for the weirdness to show up. For example, most particles aren’t entangled in any meaningful way, because interactions with other particles change their quantum state. That process is known as decoherence. (If someone wants to propose a theory of the mind based on decoherence, I might listen, especially on days when I’m distracted.)
However, other people go much further. In his bestselling 1989 book The Emperor’s New Mind, mathematical physicist Roger Penrose proposed that the problems of interpreting quantum states implies that the conscious mind will need a new kind of physics to describe it. Penrose is no crackpot in his area of expertise (the mathematics of general relativity, which also happens to be my area), but his foray into the mind and consciousness is a cautionary tale.
Just because you’re a world expert in one branch of science doesn’t qualify you in any other discipline. As Zach Weinersmith’s painfully funny comic points out, this is a particularly bad habit among physicists.
Some of them think that the overwhelming success of modern physics gives them the ability to pronounce judgment on other sciences, from linguistics to paleontology. Celebrity physicist Michio Kaku is a particularly egregious example, getting evolution completely wrong (see this critique) and telling infamous crackpot Deepak Chopra that our actions can have effects in distant galaxies. Then there are the physicists—including Freeman Dyson, one of the architects of the quantum theory describing interactions between light and matter—who contradict climate scientists in their own area of expertise.
Physicists aren’t the only culprits, though. A new book by neuroscientist W. R. Klemm implies that the edges of physics could provide answers about human consciousness. Ironically, he writes, “I just hate it when physicists write about biology. They sometimes say uninformed and silly things. But I hate it just as much when I write about physics, for I too am liable to say uninformed and silly things—as I may well do here.” Nearly everything that follows in the book excerpt is either wrong or misleading. I could write a point-by-point response, but suffice to say: The problems and incompleteness he cites about quantum physics are overblown and frankly incorrect.
I take it back: I will rant briefly about two of his points. First, Klemm writes, “But is mass really identical to energy? True, mass can be converted to energy, as atom bombs prove, and energy can even be turned into mass. Still, they are not the same things.” That’s an unnecessary obfuscation: Einstein’s equation E = mc2 does connect mass and energy in a fundamental and entirely unmysterious way. Probably no other single equation has inspired as many popular explanations, so it’s safe to say we get it: Mass is a form of energy. To be precise, it’s the energy a particle has when it’s at rest. Sure, there are complications in particle physics collisions at high speeds, but the basic concept is really simple.
Second, dark energy—which I have written about for Slate—does not impart energy to galaxies or anything smaller. If it turns out to be “vacuum energy,” which looks probable, then the only way dark energy could have anything to do with human consciousness would be if our heads were empty.
The problem with Klemm’s assertions, as well as those of many others who misuse the word quantum, is that their speculation is based on a superficial understanding of one or both fields. Physics may or may not have anything informative to say about consciousness, but you won’t make any progress in that direction without knowing a lot about both quantum physics and how brains work. Skimping on either of those will lead to nonsense.