I've read that consciousness, and a "soul", might be connected by quantum entanglement. As I understand it, "warm temperature quantum vibrations in microtubules" in neuronal cells generate EEG, or brain waves. Then, after death, the quanta that once generated electrochemical activity in the neocortex, somehow gets dispersed throughout space-time. And these particles are then linked by quantum entanglement. This phenomenon could encode, or preserve, information within the space-time fabric indefinitely, outside of a physical body. Could this be possible supporting evidence for the existence of a soul?

The rule of thumb when you hear someone claim that quantum mechanics explains or underwrites something about minds is to be very, very suspicious.

Let's suppose that two particles within some microtubule get entangled. (Caveat: I know more or less nothing about microtubules, but that won't matter for what follows.) Now suppose that these particles get dispersed into spacetime. The chance that these particles will remain entangled for any significant length of time at all is near enough to zero that the difference isn't worth arguing about. That's because if anything else interacts with either particle, the entanglement will be destroyed. Entanglement is very fragile. In entanglement experiments, physicists have to go to great lengths to prevent decoherence—the process by which interaction with the environment destroys entanglement, or more accurately, disperses it into the environment, in effect diluting it.

But even if the two particles somehow stayed entangled, this wouldn't give us any special reason to think there are souls.

Suppose we make extremely detailed records of all sorts of information about Bob: brain scans, answers to questionnaires, biographical details, samples of genetic material—whatever you like, all ket up-to-date. Suppose that after Bob dies, we make lots of copies of this information, and store the copies in separate, highly-protected environments. Would this provide an argument for the soul? After all, this information has a much better chance of lasting indefinitely than information stored in an an entangled quantum state.

Maybe the response would be that this information isn't woven into the fabric of space-time. But why is that relevant? What does our concept of a soul have to do with being woven into space-time?

Or maybe the reply is that the different records are merely independent copies that don't form a unified whole. But even if an entangled quantum state is a unified whole, does it have the kind of unity we care about in thinking about minds, persons, consciousness, what have you? If so, how? I'll have to admit that I'm having trouble seeing it.

And consider this. There are many microtubules within the brain. So there might be many different small collections of entangled particles within one person's brain. (I'll assume for the moment that this is true.) But if w and x are entangled, and y and z are entangled, the collection w, x, y and z isn't thereby an entangled whole. In fact, it's a feature of the math of entanglement that entanglement is "monogamous", i.e., can't be shared with other systems. The more tightly entangled x and y are, the less they can be entangled with anything else. There's no chance at all that anyone's brain is composed of a set of constituents that form a massively entangled whole.

The word "entanglement" has proved to be much more suggestive than Schrödinger ever expected it to be. Quantum entanglement is important and fascinating. Its metaphysical significance is a matter of ongoing debate. Meanwhile, perhaps there are immortal souls, but it's hard to see how quantum entanglement could give us any special reasons for thinking so.

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