Information conservation, entropy increase and statistical irreversibility for an isolated system

We consider statistical irreversibility and its compatibility with reversible dynamics. The role played by the observation is analyzed in detail. It makes our previous proof for the second law of thermodynamics clearer. On this basis, we emphasize the importance and wide applicability of the second law of thermodynamics. A new form of physics with this law substituted by the principle of information conservation is suggested. By the way, we also solve the paradox of Schrödinger cat, and show that the universe will not go to the so-called heat death spontaneously.