The quantum in consciousness

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I recently read Anil Seth’s Being You. It was an insightful and entertaining read, which I’d recommend for anyone interested in where the current zeitgeist sits on the topic of consciousness science.

While some say we have “made no progress” in understanding consciousness, Seth disagrees. The subtitle of the book is a new science of consciousness. However, my high-level takeaway on our current understanding of consciousness is that many new paths have been identified, but most are still just poking at the surface. There isn’t really one new science to rule them all, but many promising new ideas that have refined our understanding of the big question.

It all seems very complicated from the outside, but this is where Seth shines and is exactly why he is considered one of the best popularizers of the topic. What Seth brings to the table is an underlying philosophy grounded in physicalism that allows us to make sense, not of a single unified science of consciousness, but of the fractured mess it probably is.

The book covers a lot of ground, including some topics closely related to quantum physics — but quantum physics itself isn’t mentioned beyond noting that it is mysterious… and also something about “quantum soup,” which may only be available in England. So, I thought I’d take the opportunity to fill in the quantum gaps, as it were.

As far as I understood, Seth subscribes to the idea that consciousness is emergent — get enough biological molecules (chiefly, neurons) working together with sufficient complexity and they will start to have experience. Of course, being emergent, consciousness is not contained in the neurons — and certainly not within the atoms comprising them — but is an effect of the way they are all connected together. In any case, if your physicalism is to be grounded in our current understanding of physics, then you will eventually be led to our old friend quantum theory. So how is quantum physics relevant to consciousness?

By leaving quantum physics out of the story, Seth is implicitly saying that quantum physics has nothing to do with consciousness. He is mostly right about this. But since everything — including the brain — is made of quantum stuff following the rules of quantum physics, this demands a bit of an explanation.

Quantum physics concerns many things. First, it teaches us some apparent facts about the world: brains are made of neurons which are made of atoms, which are all identical except for the way they are arranged to create stuff. If you are reductionist, this much you take for granted. But try as might, you will never find consciousness in the equations of quantum mechanics. This apparent paradox is resolved through the concept of emergence.

Emergence is easiest to understand through an example — birds, or at least a simple model of birds. If you haven’t been lucky enough to see a murmuration live, surely you’ve seen one on the internet or narrated by David Attenborough. Thousands of starlings flock together to make mesmerizing patterns. But how? It cannot be that one starling knows how many others are in the flock and what they are all doing, right? Indeed, our best understanding is in terms of emergence. Each bird follows its own simple instructions — but, get enough of them together, zoom out, and you will see patterns emerge from the collective behavior of all of them together.

This idea has been beautifully captured with simulated birds called boids. Boids are drawn on the screen as little bird shapes or pointed arrows, but they are really just a location in a square block of pixels. Boids ostensibly obey one rule: maintain a good distance from your nearest neighbors (avoid collisions, but don’t stray too far). You can create your own simulation of boids in this simple web app.

Make your own flock of boids at

In the above web app, you can click to create more boids. However, as you will notice in the animation, the simulation slows down remarkably long before you get bored of clicking. In fact, a recent research paper required an enormous amount of computing resources to simulate a modest 64 thousand boids. It sounds like a lot, but starlings can flock in groups of 100 thousand or more.

Now imagine instead of a 100 thousand boids, you had one for every one of the 100 trillion atoms in each of the 100 billion neurons in your brain. You could not run this simulation on a computer. Even if you had enough memory to store all the data — which you wouldn’t — each frame would take many lifetimes of the universe to render.

So, what? you wonder, why would you want to simulate that many little arrows? Well, consider this. If some new emergent behavior happens only when that number of boids were present, we would never be able to see it. There could be beautiful patterns beyond comparison that we just don’t have the computational power to create. However, if boids themselves acted like something that exists in the real world, we would be able to study the emergent behavior directly, through natural observations, and create higher-level theories of it.

This is kind of like consciousness and quantum physics. Yes, of course, it is the laws of quantum mechanics — and only those laws — that the atoms of neurons obey. But consciousness could never be derived from quantum mechanics, nor could we even simulate the interaction of all the atoms contained in a brain to test and play with its arrival.

Boids are to atoms as flocks of millions of birds are to brains. We study flocks of birds with higher-level theories that do not make reference to the fine details of the individual birds making them up. Similarly, we (well, Seth and his colleagues) study consciousness with higher-level theories that don’t make reference to the atoms in the brains giving rise to it. But in either case, it is accepted that if we could perfectly simulate enough individual birds or enough individual atoms, then we would be able to create a true murmuration or true consciousness. That is the article of faith grounding physicalism.

Before you get too disappointed at the seemingly impossible challenge of understanding emergence, note that Nature seems to have figured it out just fine. Sure, it took billions of generations of evolution, but that was random and undirected. Hopefully, we humans are smart enough to reproduce it in far less time. The best chance we have is quantum computing. Instead of trying to mimic a model of atoms with electronic chips and software, we will try to coerce individual atoms (or artificial ones) to behave in unnatural ways — that is, we are trying to control the actions and interactions of atoms to carry out functions we design for them.

I’ve written enough about quantum computing elsewhere on this blog, but suffice to say, we aren’t there yet. It may be decades or centuries before we have enough control of a brain’s worth of atoms to simulate how consciousness arises from the simple rules of individual atoms. But even then, a simulation only demonstrates that emergence happens — it is not a logical deduction of higher-level organization from a lower-level theory.

What we need is a theory of emergence that allows us to understand how to derive properties like consciousness from the fundamental rules of quantum physics. That, it seems to me, is the only ultimate goal a devoted physicalist can have. In the meantime, higher-level theories must do.

Now, you may object to the idea that quantum physics (as we currently use it) has nothing to do with consciousness (as we currently understand it). In other words, maybe real quantum effects — like superposition, tunneling, and entanglement — play an essential role in any useful theory of consciousness.

Experimental science usually lowers the bar to asking whether some aspect of quantum physics is necessary to explain observable properties of the brain during conscious activity. This overlaps with a field called quantum biology, a multidisciplinary field that looks to detail biochemical processes in living things using quantum physics. And, while this research might demonstrate some definitive aspects of quantum physics at play in particular molecular processes, it doesn’t get us any closer to the big picture since we already knew a detailed enough description of anything will require quantum physics.

The best definition we seem to have of consciousness is one cryptically given by Thomas Nagel. He said a thing is conscious if there is something it is like to be that thing. He illustratively titled his paper What Is It Like to Be a Bat? Well, if at some point we find there is something it is like to be a very cold microscopic organism, then maybe we would need quantum physics to know what it is like to be that something. What is it like to be a nearly frozen tardigrade? Perhaps quantum physics has the answer.

Speaking of speculation, quantum consciousness is a broad class of philosophical ideas that span a continuous spectrum branching all the way into pure pseudoscience. There isn’t much here that naturally fits into Seth’s physicalism. However, what might have been overlooked is how quantum physics can help define the boundaries of what is possible.

For example, in discussing notions of self, Seth invokes a thought experiment involving teleportation — the sci-fi version. He imagines a device that scans a person and then replicates them somewhere else. Crucially, the device must simultaneously destroy the original person so that two copies aren’t floating around. Now, you go to use the device, but it malfunctions, and two copies of you end up existing. Which one is the real you?

To drive the point, Seth emphasizes that the clone is a true copy — down to the last atom. There is no “right” answer to the question and I won’t reproduce the discussion, but this is mostly because it is moot to begin with. Quantum physics forbids cloning. All the people worrying about the consequences of this thought experiment are wasting their time — it could never be done, even in principle.

As more of the higher-level theories of consciousness become couched in terms of information theory, the more relevant quantum physics may become. Since the dawn of quantum information science, we have learned much about the ultimate limitations quantum physics imposes on the ability to store, process, and communicate information in the universe. Surely these should impact ideas about consciousness. I think it’s a safe bet that at least the 10th-anniversary edition of Being You will discuss quantum physics. I look forward to it. But, until then, I am glad Seth brought me up to speed on the state of the art.




Quantum theorist by day, father by night. Occasionally moonlighting as a author.

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Chris Ferrie

Chris Ferrie

Quantum theorist by day, father by night. Occasionally moonlighting as a author.

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