Damage spreading phenomena are defined artificially in the dynamics of the Ising spin systems in computer simulation. Random numbers used in computer simulations play a role to evolve the system to thermal equilibrium states. When the dynamics is taken not only as an artificial tool which realizes an equilibrium state but also as some physical process, damage spreading phenomena can be interpreted as physical objects. It is a main aim to give a concrete physical image to damage spreading phenomena which is artificially defined in original. Key property is a response for thermal noise by the interaction with a heat bath. Damage spreading as a phenomenon in time series is related with a spatial property in the percolation image of the Ising model by interpreting the Fortuin-Kasteleyn representation as a percolation image of the Ising models. This time-space relation reveals the essence of damage spreading as critical phenomena in physical systems.