Ever so often a piece of pop science writing pops up that stands out. It's like a good bottle of wine, you want to savour it slowly, and the next day when you wake up with a slight hangover and realize that maybe it was a bit disagreeable, you are still content that you have some more of it in your cellar.
Penrose's "The Emperor's New Mind" falls into this category for me. Despite all of the author's immense scientific sophistication, it felt like he fell into the trap that my very first physics prof put like this: "The difference between theologians and philosophers is that the former have to argue towards a certain end." In the final analysis, I find, it was a religious text.
After an exhausting rekindling of the D-Wave melee on his blog, Scott Aaronson's latest paper, "The Ghost in the Quantum Turing Machine", is a welcome change of pace. Yet, given the subject matter I was mentally preparing for a similar experience as with Penrose, especially in light of the instant rejection that this paper received from some experts on Bayesian inference, such as Robert Tucci.
Scott's analysis may be dismissed as Copenhagen Interpretation on steroids, but while the innate problems with this old QM workhorse are quite apparent, in the end I think it actually manages to yet again deliver a plausible result (despite some apparent absurdities along the way). The structure of the essay is quite clever, as Scott anticipates many objections that could be raised, and at times it almosts reads like a 21st century version of a Platonic dialog. I think he missed some issues, and I will revisit this in a later post, but overall I think the big picture holds, and it is well painted.
Scott has always been a good writer. His book "Quantum Computing since Democritus"
I find thoroughly enjoyable. Although unlike the Hitchhiker's Guide to the Galaxy (the real thing, not the book) it still had to fit the dead tree format, and so there are gaps in the millennia of QC history covered. Scott had to pick and chose what's most important to him in this story, and that means that the 495 complexity classes known to humanity these days get a fair share of attention. After all, he is a complexity theorist. Even to the best writer, making that part flow like honey will be difficult, but it gives an excellent window into how Scott approaches the subject. It also lays bare that the field is in similar dire straights as physics was, when the number of elementary particles exploded without much understanding of exactly what was going on. So for now, we are stuck with a complexity class zoo rather than an elementary particle one, waiting for some kind of standard. model that'll impose order.
This latest, more contemplative paper is unburdened by this particular heavy load, yet takes on another one: The age old philosophical question of free will, which is very close to the question of consciousness and AI that Penrose pondered. It starts out with a beautifully written homage to Turing. The last piece of writing that resonated this strongly with me had an unapologetically religious sub-text (this blog entry penned by Kingsley Jones). So I was certain I was in for another Penrose moment.
The bait and switch that followed, to the much more decidable question of what minimal necessary resource nature needs to provide to make free will a valid concept, came as a pleasant surprise. All the more, as this question seems so obvious in hindsight, but apparently hasn't been refined in this manner before.
It is a very good question, an important one, but for now your inclination toward or away from belief in this resource (which goes by the name Knightian uncertainty) is up to your religious leanings, and I don't know if you actually have the freedom to make this choice.