Not really? If you know linear algebra, you can pick up on the quantum terminology very easily. The best short explanation of QM I've come across is Scott Aaronson's QM in one slide (slide #2 of this powerpoint, read the notes at the bottom of the slide). The difference between classic mechanics and quantum mechanics, in some sense, boils down to whether you use a 'probability distribution' (all values real and non-negative) or a 'wavefunction' (values can be complex or negative) to store the state of the world. The wavefunction approach, with its unitary matrices instead of stochastic matrices, allows for destructive interference between states. That's just background; the discussion in that article all lives in wavefunction territory. Everyone agrees on the underlying mathematics, but they're trying to construct philosophical arguments why a particular interpretation is more or less natural than competing interpretations. [...] That's easy to elaborate on, because it works the same in a quantum and classical universe. But it's not clear to me what part of that you're having trouble comprehending, since it looks clear to me. If it were the case that everything in the universe were 'materially' connected, then you could not reason about any individual part of the universe without reasoning about the whole universe. Instead of being able to say "balls fall towards the Earth when let go," we would have to say "balls fall towards the center of the Earth, the Sun, Jupiter, the Milky Way Galaxy, the...". Note that the second is actually truer than the first (if you define 'center' correctly), but the difference between the two of them can be safely ignored in most cases because the effects of the other objects in the universe on the ball are already mostly captured by the position of the earth; to put this in probabilistic terms, that's the statement P(A)=P(A|B), at least approximately, which means that A and B are independent (at least approximately).