"Could a quantum computer have subjective experience?" by Scott Aaronson

People who are into physics and follow blogs actively have surely ran into MIT physicist Scott Aaronson, probably most well known for his critiques of the alleged D-Wave quantum computer. More recently, Scott has been writing a lot about consciousness, but his latest post – prepared talk notes from the Quantum Foundations of a Classical Universe meeting – is a real doozy.

The post is a long read, and here's the juicy bit to entice you:

The intermediate position that I’d like to explore says the following. Yes, consciousness is a property of any suitably-organized chunk of matter. But, in addition to performing complex computations, or passing the Turing Test, or other information-theoretic conditions that I don’t know (and don’t claim to know), there’s at least one crucial further thing that a chunk of matter has to do before we should consider it conscious. Namely, it has to participate fully in the Arrow of Time. More specifically, it has to produce irreversible decoherence as an intrinsic part of its operation. It has to be continually taking microscopic fluctuations, and irreversibly amplifying them into stable, copyable, macroscopic classical records.

Before I go further, let me be extremely clear about what this view is not saying. Firstly, it’s not saying that the brain is a quantum computer, in any interesting sense—let alone a quantum-gravitational computer, like Roger Penrose wants! [...]

Secondly, this view doesn’t say that consciousness is in any sense necessary for decoherence, or for the emergence of a classical world. I’ve never understood how one could hold such a belief, while still being a scientific realist. [...]

Thirdly, the view I’m discussing doesn’t say that “quantum magic” is the explanation for consciousness. It’s silent on the explanation for consciousness (to whatever extent that question makes sense); it seeks only to draw a defensible line between the systems we want to regard as conscious and the systems we don’t—to address what I recently called the Pretty-Hard Problem. [...]"