Hooray for quantum mechanics! I know little about physics, so all I can say is that just because we don't know how something is determined, doesn't mean it isn't. I think a similar argument was made about the decay of radioactive particles in the "are we free" thread. Bell's theorem says it is mathematically impossible for a "hidden factor" to exist. Thus, radioactive decay, amongst other things in quantum mechanics, is truly random. The notion of there being some mysterious X factor that we couldn't understand or observe has been around for a long time and even supported by Einstein, but as Bell showed, this is not the case. Of course from a epistemological viewpoint, you could say that our system of math is simply wrong or imperfect in that regard.