Some intuitional questions concerning Sakurai's QM. Hello! I've just started reading Sakurai 's 'Mordern Quantum Mechanics' and open this thread for smaller intuitonal wonderings / questions. Some of them I might be able to solve myself with some help from you guys and others are of the sort that I'll just need clarification from people with a better understanding of QM and the mathematics. If you think I'm close to the answer feel free to not answer the whole question but just give some leading points. :) So far my wonderings are: 1. The relation between ket's and bra's is a complex conjugation of the vector/function. Is there any mathematical term for spaces with this kinds of metrics (it doesnt seem like a metric describing a Riemannian manifold)? Is there any pro's or cons to consider the hilbert space as a tangent space of a bigger structure, a manifold? I.e. will I encounter concepts such as parallell transport in QM later? 2. Sakuari talks about how the measurements 'destroys information' of the previous state. Where can I find more information about this? It seems as if I should have heard about it before since the lost of information is a big deal in physics. :) Thanks really much! ps. tried to correct the title but the edit doesnt seem to update it.