  Quantum theory (QT) has been confirmed by numerous experiments, yet we still
cannot fully grasp the meaning of the theory. As a consequence, the quantum
world appears to us paradoxical. Here we shed new light on QT by having it
follow from two main postulates (i) the theory should be logically consistent;
(ii) inferences in the theory should be computable in polynomial time. The
first postulate is what we require to each well-founded mathematical theory.
The computation postulate defines the physical component of the theory. We show
that the computation postulate is the only true divide between QT, seen as a
generalised theory of probability, and classical probability. All quantum
paradoxes, and entanglement in particular, arise from the clash of trying to
reconcile a computationally intractable, somewhat idealised, theory (classical
physics) with a computationally tractable theory (QT) or, in other words, from
regarding physics as fundamental rather than computation.
