Need clarification on "quantum indeterminism" Hi, I should start off by saying that I am not physicist, nor am I a physics student, however I have lately been in need of some clarification on basic quantum physics. My question is this, does quantum mechanics contradict the idea of cause-and-effect? I have read about Heisenberg's uncertainty principle, but I am confused as to whether it is stating that there is only one "real" possible location for a quanta, or that our trying to observe said quanta is what causes the "uncertainty"? Perhaps another way of saying it would be: if we repeated the same experiment under the same conditions on the quantum level, could we possible end up with different results? (Hence "indeterminancy.") Sorry if this sounds incoherent, as I stated earlier, I am no physicist. Any answers (particularly ones with references) are appreciated in advance.