I'm not sure who you're talking about because I'm the person above referring to someone writing on paper--and the paper was meant to also be within the simulation. The simulator is "reading the paper" by nature of having perfect information about the system.
"Reversible" in this context is only meant to describe the contents of the simulation. Computation can occur completely reversibly.
Sorry, got mixed up with cameroncowan. Anyway, to the original point:
You said "Once they've finished the proof, you record what's written on their paper, and reverse the entire simulation... Looking at what they wrote on the paper doesn't mean you have to communicate with them."
My interpretation--which may be wrong--is that you are suggesting that the person running the simulation record the state of the simulation at the moment the problem is solved, or at least the part of the simulator state having to do with the paper. However the process of ...
Yet another exceptionally interesting blog post by Scott Aaronson, describing his talk at the Quantum Foundations of a Classical Universe workshop, videos of which should be posted soon. Despite the disclaimer "My talk is for entertainment purposes only; it should not be taken seriously by anyone", it raises several serious and semi-serious points about the nature of conscious experience and related paradoxes, which are generally overlooked by the philosophers, including Eliezer, because they have no relevant CS/QC expertise. For example:
Scott also suggests a model of consciousness which sort-of resolves the issues of cloning, identity and such, by introducing what he calls a "digital abstraction layer" (again, read the blog post to understand what he means by that). Our brains might be lacking such a layer and so be "fundamentally unclonable".
Another interesting observation is that you never actually kill the cat in the Schroedinger's cat experiment, for a reasonable definition of "kill".
There are several more mind-blowing insights in this "entertainment purposes" post/talk, related to the existence of p-zombies, consciousness of Boltzmann brains, the observed large-scale structure of the Universe and the "reality" of Tegmark IV.
I certainly got the humbling experience that Scott is the level above mine, and I would like to know if other people did, too.
Finally, the standard bright dilettante caveat applies: if you think up a quick objection to what an expert in the area argues, and you yourself are not such an expert, the odds are extremely heavy that this objection is either silly or has been considered and addressed by the expert already.