so now i'm finally getting to grips with the maths of quantum mechanics, i'm getting really confused about what it means physically. sorry this is quite long but it seems like the more i think about quantum mechanics, the more my understanding of it disintegrates. first, does quantum mechanics actually say what a particle is, or what its doing? as i understand it, a particle is described by a wavefunction which doesn't actually 'exist' but probability information can be derived from it. is that right? it seems strange to me that you have a theory which doesn't actually tell you what's going on, it just predicts results. what about de broglie waves? are they the same things as wavefunctions? i'm guessing not, because de broglie waves have real wavelengths and stuff but wavefunctions are complex - is that right? if so, then what are de broglie waves? then there's the double slit experiment. first i'm a bit confused about which double slit experiments have actually been done, and which are thought experiments. i know its been done with light, electrons, and single electrons, but what about the one where an electron is detected going through one of the slits - has that actually been done? if someone could give me a paper reference or something that would be great. in the case of the one electron at a time experiment, where a single electron interferes with itself, i don't actually know what is meant by waves in this context. are we talking about actual physical waves, or wavefunctions which just give probability information? i used to interpret it like this: a wave (a physical thing that exists) goes through the slits and an interference pattern is observed, so the electron must have gone through both slits simultaneously. now i'm starting to think that's wrong and i'm getting horribly confused. do you instead have a wavefunction (that doesn't physically exist) going through a slit, which then interferes with another wavefunction which went through the other slit, resulting in a probability distribution which gives the interference pattern? i.e. two wavefunctions in different places but only one electron. or, do you have one wavefunction that goes through both slits together and then evolves so that the interference pattern is obtained? i.e. one wavefunction, one electron. or is it something different? i'm hoping if i can make sense of this, i might be able to make some sense out of what happens when you observe an electron going through one of the slits. one final thing; if you shoot single electrons through a single slit, do you get a peak that decays (like light), or do you just get a line?