I'm a biology student, but I take some interest in physics and have read 2 of Stephen Hawking's divulgation books about modern physics and often stop to read something about it in wikipedia. Wich has revealed to obviously not be enough to understand some characteristics of Quantum Mechanics. Even knowing the answers are on the article I'm reading on wipedia, I'm not able to understand it well, probably because they are written by physicists and therefore to some point for physicists. So I searched for some physics forum where maybe I could get some more friendly explanations. :P Can anyone help me? The main matter that annoys me about Quantum Mechanics and to many other people it seems, is the apparent randomicity or probability it brings, making the determinable universe I always liked to think of impossible. But I'm not able to understand where this probability comes from. I can understand that through the uncertainty principle, precise measures for both of a pair of characteristics for a particle or wave become unreachable for us, but that doesn't means the system itself doesn't have definite values, does it? I can understand the uncertainty principle through the observer effect, observing changing the observed, but it seems that's not quite the nature of the principle. I read somewhere you could get a measure observing some particle entangled to another, getting information on it without disturbing it. However, does a particle get entangled for position or momentum too, I've always seen examples for spin? Is there a pair for uncertainty also for spin? But if measures can be made undirectly, where does the uncertainty arise from? Can't one measure both position and momentum for it precisely undirectly like that, without uncertainty? Initially well defined states for wavefunctions start getting less precise over time, why is that? From wikipedia, it seems it is possible to measure else position or momentum quite exactly without getting the other measure. Does the lack of a measure in position influence the state of momentum over time? Wavefunctions describe reality through probability values over time. But why does reality HAVE to coincide with the wavefunctions, why can't they be merely an aproximation of our reality due to unknown variables? In wikipedia it says John Bell has theorized creating a quite reasonable theorem saying that if there were unknown variables, they should equally affect all particles, creating a correlation and therefore being detectable. But couldn't the variables have different states for different particles, creating different tendencies? Or maybe the same state on different particles being affected by similar but non equal conditions on the system? My main question would be why does quantum mechanics have to suppose a probabilistic universe. And why do physicists seek for so unnatural explanations to justify it in the different interpratations of quantum mechanics. Why can't quantum mechanics be just the model to describe a system and the wave function collapse be origined on its true nature revealed. I manage to see ways out of it in my personal view, but I realize they're due to my limited knowledge on it. Sorry for the large amount of (likely stupid) doubts I've brought. And also for any english mistakes/incoherences. I'll be really thankful if anyone can answer any of those questions.