Prompted by Mitchell Porter, I asked on Physics StackExchange about the accuracy of the physics in the Quantum Physics sequence:

What errors would one learn from Eliezer Yudkowsky's introduction to quantum physics?

Eliezer Yudkowsky wrote an introduction to quantum physics from a strictly realist standpoint. However, he has no qualifications in the subject and it is not his specialty. Does it paint an accurate picture overall? What mistaken ideas about QM might someone who read only this introduction come away with?

I've had some interesting answers so far, including one from a friend that seems to point up a definite error, though AFAICT not a very consequential one: in Configurations and Amplitude, a multiplication factor of *i* is used for the mirrors where -1 is correct.

Physics StackExchange: What errors would one learn from Eliezer Yudkowsky's introduction to quantum physics?

Mirror matter comes from "N=2" supersymmetry, where along with the usual particle and its superpartner, you have a mirror partner for both of those. Ordinary "N=1" supersymmetry doesn't have the mirrors. N=2 supersymmetry is of major interest mathematically, but it's difficult to get the standard model from an N=2 theory. But if you did, the mirror matter might be the dark matter. It's in my top ten of cool possibilities, but I can't say it's favored by Occam.

I'd be interested in reading more about your top ten cool possibilities. They sound cool.