I’m not going to try to argue that consciousness arises from some mysterious quantum activity within the atoms making up the brain’s neurons. As a scientist, I know better. As a cognitive scientist, I know that, though it is not fully understood how consciousness arises from neural activity, consciousness does indeed arise from that neural activity. No neural activity, no consciousness—simple as that. I also know just enough about physics to know that quantum phenomena are (as I understand) limited to subatomic particles (though atoms can sometimes act like quantum particles), so there’s no way that neurons, which are composed of cells, which are composed of molecules, which are composed of atoms, could behave quantumly. No. Neurons must obey the laws of classical mechanics, not quantum mechanics.
Also, as Matthew Francis, with warrant and good reason, exhorts in this post, it is often a grievous error to apply quantum models to other mysterious phenomena, noting that, when this is done, the person has either misunderstood quantum mechanics or the other phenomenon of interest. However, his exhortation is against those who argue that quantum mechanics is what underlies these other mysterious phenomena. It was never my intention to argue that case for consciousness. As I said above, cognitive science tells us that’s not how consciousness works. So rather than argue that quantum processes give rise to consciousness, I will argue that quantum mechanics makes for an effective and compelling analogy for explaining how consciousness works. That is, perhaps thought functions not unlike a quantum particle and consciousness arises from brain function as a not wholly predictable process, similar to how quantum phenomena arise rather unpredictably from quantum particles. (Clarification: both consciousness and quantum phenomena are predictable, just not deterministically so. You can have a good guess of what might happen—or, another way, you can know the likelihood of the things that could happen—but you can’t be certain of a given outcome ahead of time.)
Let me start with how this idea began. I was at a talk several weeks ago and the speaker was talking about how she and her research team sampled people about their thoughts at random points throughout the day, asking things like what their most recent thought was, whether it was about the past or future, if it a desire, and other such things. It made me wonder how many more thoughts I would experience on a daily basis if only I were similarly asked to report on them. As a cognitive psychologist, I know that our brains never stop working and that they do a lot of work (which can be considered cognition or thought) below the level of conscious awareness; but I’m not talking about those thoughts. I’m talking about those small thoughts in the back of your mind. Thoughts that are definitely there but that you’re not really aware of because your attention is focused on something else. Thoughts like how comfortable you feel in that chair or like figuring out how much time you have before your meeting so you know how fast you have to work to get your stuff done before then. How easily do those thoughts come and go without our really knowing? I’m inclined to say that there are multitudes of those thoughts that come and go without ever leaving a footprint on our minds—or a thoughtprint, if you will. That’s not to say that these thoughts don’t affect our behaviors and decisions, because they almost certainly do. Indeed, the unconscious mind can exert some amazingly high-level effects on our behaviors and decisions. (That’s a whole separate topic, maybe one for another post someday, perhaps in conjunction with a discussion of free will…) Rather, it’s just that perhaps we’re not aware of those thoughts unless we actively attend to them, unless we observe them…which is how quantum particles behave.
There are plenty of great resources out there on the Internet about quantum physics that will do a better job than I could, so I’ll leave the teaching of the quantum mechanics to them. I’ve included links to some good videos at the end of this post for the curious reader. Plus, I’m no physicist (though I like to think I understand the gist of quantum mechanics well enough), so I’ll keep my explanation and discussion of quantum phenomena simplistic (because that’s all the better I understand it) and along the lines of how it relates to consciousness.
Perhaps the most fundamental quantum phenomenon, and the one relates to my experience at the talk as I thought about thoughts, has to do with the wave-particle duality of quantum particles. Basically, the wave-particle duality is the fact that quantum particles act as both a wave and a particle. They act like a wave in how the travel and disperse (e.g., light is an electromagnetic wave) but like a particle in how they interact with other particles and objects (e.g., photons, the quantum constituents of light, interact with photoreceptors in our retinas to produce sight). How can this be? Well, essentially, until they interact with something, quantum particles act/exist as a wave—a probability wave, to be more precise. For example, as light is emitted from a flashlight, photons propagate out as probability waves, with those waves determining how likely it is that any given photon will land on a particular spot on the ground at which you’re shining your flashlight. Maybe there’s a 90% chance that it will land on the patch of grass on the ground and a 10% chance it will land on the adjacent dirt. That means that, on average, nine photons out of ten will hit the grass, with the remaining one hitting the dirt. That also means that, if you emit a single photon at a time, it will hit the grass, on average, nine times out of ten.
You might be thinking that that’s not really interesting (not to mention that it doesn’t seem to relate to consciousness), so here’s the really cool part: it’s not just that quantum particles exist as probability waves until they interact with something; they also stop behaving like a probability wave whenever they’re observed by something. The simple act of observing a quantum object forces it to become a particle and assume a location based on its probability wave (it can particleize at a point anywhere within in that probability wave). It will most likely be at the densest (i.e., the most probable) location, but on any given observation, it could choose to appear in the location that has only a 0.00001% probability. (Yes, I realize I anthropomorphized quantum particles by saying they can “choose” to appear in locations. That was intentional. If something can behave in a way that seems like it knows whether or not it’s being observed, I think a little bit of anthropomorphizing is warranted. 😉 )
Now you might be thinking that quantum stuff is pretty cool, but you’re probably still wondering how that relates to consciousness. Here goes: just as observing a quantum particle forces it to “become” a particle, I wonder if the act of observing (i.e., thinking about) a thought is what makes it “become” a “thought”—that is, a consciously, actively experienced thought. Perhaps until I observe a thought, it goes propagating through my brain according to its own kind of probability waves, only particlizing into a conscious thought when it is observed (i.e., by my own conscious thoughts) or interacts with some other thought, idea, feeling, etc. But what might those “probability waves” be in the realm of mental activity? Physically, they would be neural connections. A thought cannot go from one area of the brain to another without traveling there along neurons. More abstractly (though still grounded in the physicality of neural connections), these probability waves are semantic relationships. It has long been known by cognitive psychologists that the brain is organized semantically, yielding a phenomenon called spreading activation. Spreading activation is the unconscious process whereby neural activity spreads from one idea to another. The key is that it is unconscious; you can’t make it happen. Neither can you stop it from happening. So, when I hear or read the word dog, it is going automatically activate semantically related concepts (e.g., cat, walk, leash, bark, puppy, etc.) and relevant memories. Thus, through these processes, a given thought can do some impressive mental acrobatics, ending up in places seemingly unrelated to where it began.
Hence our experiences of “random” thoughts. There’s no way they’re ever actually truly random (hence the scare quotes). Whether it’s a thought you had, something you saw, something someone said, or any number of other stimuli, something sparked that thought; it’s just that, to an outsider (and maybe even to yourself, depending on how consciously aware you were of the paths that that thought traveled), that thought appears random with respect to the current context. This is related to another phenomenon of quantum particles: quantum tunneling. Because of the probabilistic nature of the location of quantum particles, they have the ability (albeit with a very low likelihood) to suddenly appear on the other sides of objects through which they shouldn’t be able to pass, thereby giving the appearance that they tunneled through that object. How can that happen? Again, it comes down to the probabilistic nature of quantum particles. As long as at least some part of the probability wave extends to the other side of that object, a quantum particle can particlize on the other side of that object. This is how “random” thoughts appear to act: seemingly out of nowhere and without reason, a thought has tunneled from its geneses through the barrier to consciousness. But you can bet that underlying that seeming randomness is spreading activation. You weren’t aware of it happening, but the semantically organized neural connections of your brain formed the probability wave along which that thought traveled.
I’ll end with what is perhaps the most mysterious and inexplicable of the quantum phenomena: quantum entanglement. Because this is such an odd phenomenon, I’ll jump right to an example. Electrons are characterized by their spin state. A given pair of electrons (i.e., in an atomic orbital) must always have opposing spin states. Consistent with the seemingly sentient nature of quantum particles, until an electron’s spin state is measured or observed, it is all possible spin states at once (or, perhaps more accurately, it is a probability representation of all possible spin states); once you observe it, however, you force it to choose a particular spin state. (Again, we see that in the quantum world, the seemingly passive act of observing or measuring is quite active and seemingly rather invasive.) And because the two electrons in the pair must complement one another, when you observe the spin state of electron a, thereby forcing it to choose a spin state, you also force electron b to choose the spin state opposite to that of electron a. Now here’s where it gets freaky: that complementary relationship between the two electrons holds even when those electrons are separated by great distances. Even at those great distances, once you observe the spin state of electron a, electron b, seemingly knowing that electron a has been observed, obligatorily chooses the opposing spin state. In other words, the measurement of electron a affects the concurrent spin state of the distant electron b.
Einstein himself called entanglement “spooky action at a distance”, and, indeed, it is spooky—mystical, almost. I don’t expect there to be a perfectly corresponding finding in any other realm of sciences, not even consciousness, whereby observing or measuring one thing affects its distant, entangled counterpart. However, there are some similarly spooky findings in psychology that bear some resemblance: identical twins. There are numerous stories of identical twins separated at birth who end up living lives that are eerily similar (or even the same) in terms of occupations, cars, preferences, habits, posture, etc. There’s even one story of identical twin sisters (not separated) giving birth on the same day. In some way, the lives of these twins seem entangled, even when living lives separated from one another. Granted, a lot of this of that can be attributed to identical genes, because genes hugely affect our physical attributes and influence many of our mental attributes, like personality, intelligence, religiosity, etc. These attributes can then affect desires and choices. (But that raises the question of how much choice we really have. How much are our thoughts determined by our neural makeup, and, therefore, our biology and genes? By our past experiences? Do we really have the freedom of choice, or is it an illusion? Stay tuned; I plan to write another post later on consciousness and free will.) But certainly identical genes and similar mental attributes can’t account for all of those similarities, especially since cognitive traits like personality aren’t fully genetically determined. And I can’t believe that either genetic or cognitive similarities would cause twins to go into labor on the same day despite having due dates about a week apart. What, then, accounts for these eerie similarities? I have no idea. This, too, seems like a spooky action at a distance. Conscious entanglement? It’s an intriguing thought.
Where does this leave us? Well, even I’m not entirely sure. My thoughts on the matter feel rather like a probability wave. Quantum mechanics and consciousness are two of the most mysterious and under-understood phenomena in the sciences, but I’m hoping that we can have a slightly different—maybe even better—view of one or both by looking at each through the lens of the other. Along that vein, I’m using quantum mechanics as an analogy in order to explain consciousness, not as a model of consciousness in order to understand how it works and predict its behavior. So I’m not expecting that we’ll ever discover that consciousness acts like a quantum particle; as noted earlier, I don’t think that’s a sensible theory. The quantum mechanical properties of quantum particles are unique to quantum particles and do not translate well to other particles or objects, such as cells and neurons. So I’m not naïve enough to think that we’ll ever find a consciousness equivalent of quantum tunneling or quantum entanglement. However, that is not to say that looking at consciousness through the lens of quantum phenomena is a fruitless endeavor. Looking at consciousness this way can alter how we view consciousness and the questions we ask about it, which can, in turn, influence how we research it and what we discover about it, which can, in turn, offer helpful, practical applications.
Neuroscience tells us how neurons connect and how those connections strengthen and weaken with use (or lack thereof), but that doesn’t mean that we know what thoughts are associated with which states of activity, and it’s possible that we never will, perhaps because it’s not possible that we can. But, if we started treating consciousness as quantum and started thinking about thoughts in terms of probabilities, maybe we could characterize the probability spaces of particular thoughts and the probability waves associated with the propagation of those thoughts. If we knew this, then perhaps we could develop more effective ways of (re)training thoughts and thought patterns so to have a decreased likelihood of having unhealthy and dysfunctional thoughts (distressing thoughts, depressive thoughts, anxious thoughts, discouraging thoughts, disturbed thoughts, etc.) and a greater likelihood of living healthier thoughts lives. Perhaps a perspective on consciousness as quantum will revolutionize and deepen our understanding of consciousness, just as the quantum perspective on physics revolutionized and deepened our understanding of the physical universe.
D. R. Meriwether
Videos on Quantum Mechanics
~Here is an excellent NOVA special on quantum physics starring Brian Greene. The explanation of the wave-particle duality (illustrated with the double slit experiment) is from 14:08 – 20:32. The explanation of entanglement is from 27:40 – 37:22. The rest is great, too, as are the other three videos on the series.
~Here is another excellent video on the double slit experiment. This one talks about the role of observing the particles in affecting the results.
Stories of (Separated) Twins
~This article talks about some of the intriguing findings on separated twins, but focuses more on the research behind why identical twins are so similar.
~This page gives several amazing anecdotes and surprising facts about twins.