Why do billiard balls does not pass through both the slits at once or tunnel through walls while electrons and photons do? Quantum phenomena are observed at room temperatures so how does decoherence theory account for such phenomena? I think only Caslav Brukner and Johannes Kofler have seriously addressed this question. Classical world arising out of quantum physics under the restriction of coarse-grained measurements. A coarse-grained Schrödinger cat Do classical laws arise from quantum laws? Does this really solve the problem?