Scott Aaronson (interviewed):
… after all the forbidding-sounding verbiage you read in popular books, quantum mechanics is astonishingly simple — once you take the physics out of it! In fact, QM isn’t even “physics” in the usual sense: it’s more like an operating system that the rest of physics runs on as application software. It’s a certain generalization of the laws of probability. It says nothing directly about electrons, photons, or anything like that. It just talks about lists of complex numbers called amplitudes: how these amplitudes change as a physical system evolves, and how to convert them into the probability of seeing this or that result when you measure the system. And everything you’ve ever heard about the “weirdness of the quantum world,” is simply different logical consequences of this one change to the rules of probability. This makes QM, as a subject, possibly more computer-science friendly than any other part of physics. In fact, even if our universe hadn’t been described by QM, I suspect theoretical computer scientists would’ve eventually needed to invent quantum computing anyway, just for internal mathematical reasons.
Just when you thought it was safe to go back in the water:
Scavenged without comment:
Eliezer Yudkowsky and Scott Aaronson talk Technological Singularity and Many Worlds (from summer 2009). Peculiarly, given the trend of the conversation, it’s aged well.
The Paperclip Maximizer is on its way to becoming the most significant bad argument in existence. EY’s high-intensity rants about how thoroughly one-world theories are busted, however, are truly awesome. You have to hang on to the end to reach Dr Evil (but it’s worth it).
Extracted from a consistently fascinating post on quantum computation and consciousness by Scott Aaronson:
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.
The immediately subsequent clarification is also crucial: “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! Indeed, I see no evidence, from neuroscience or any other field, that the cognitive information processing done by the brain is anything but classical.”
Once seen, this is an argument that cannot be unseen. (It’s almost an instance of consciousness-production through ratcheted decoherence in itself.)