The latest round of the debate between Aram and Gil Kalai is now up over at Goedel’s Lost Letter.
I realize that I’m preaching to the choir at this venue, but I thought I would highlight Aram’s response. He nicely sums up the conundrum for quantum skeptics with a biblical allusion:
…Gil and other modern skeptics need a theory of physics which is compatible with existing quantum mechanics, existing observations of noise processes, existing classical computers, and potential future reductions of noise to sub-threshold (but still constant) rates, all while ruling out large-scale quantum computers. Such a ropy camel-shaped theory would have difficulty in passing through the needle of mathematical consistency.
One of the things that puzzles me about quantum skeptics is that they always seem to claim that there is an in principle reason why large-scale quantum computation is impossible. I just completely fail to see how they infer this from existing lines of evidence. If the skeptics would alter their argument slightly, I might have some more sympathy. For example, why don’t we power everything with fusion by now? Is it because there is a fundamental principle that prevents us from harnessing fusion power? No! It just turned out to be much harder than anyone thought to generate a self-sustaining controlled fusion reaction. If skeptics were arguing that quantum computers are the new fusion reactors, then I can at least understand how they might think that in spite of continuing experimental progress. But in principle impossible? It seems like an awfully narrow needle to thread.