I spoke with Nima about this a few months ago. He isn't saying that sometimes all probabilities don't add up to one, he is constructing a physical theory witho

I spoke with Nima about this a few months ago. He isn't saying that sometimes all probabilities don't add up to one, he is constructing a physical theory without assuming that as a precondition. It is a consequence of the theory and develops, but he said that if he can explain unitarity in terms of other phoenomena, then there is probably something more fundamental happening, possibly new physics.