 In many models of decoherence, the preferred states are robust in an even stronger sense, because information about them is stored in a redundant way in the environment (say, because a Schrödinger cat has interacted with so many stray particles: photons, air molecules, dust). This information can later be acquired by an observer without further disturbing the system (we observe – however that may be interpreted – whether the cat is alive or dead by intercepting on our retina a small fraction of the light that has interacted with the cat). 