I know that on the smallest scales, general relativity predicts that space-time is flat. But I've also read that space-time can be described as a sort of "quantum foam" for distances smaller than the Planck length. Isn't this something of a contradiction (one more way in which quantum mechanics and general relativity disagree)? To make matters worse, theories about quantized space-time means that space-time could be "discrete", and not smooth at all.
So which principle does the physics community think is right? The idea of smooth, locally flat space-time, or the idea of "block-like", discrete space-time?