For the astronomical theory, see Steady state theory
The term "steady state" describes a system in which no variables have a time dependence. This means that all derivatives with respect to time equal zero and no variables are functions of time. Note that steady state does not necessarily imply equilibrium. A good "test" for determining if a system is at steady state is to physically or mentally turn your back to the system. When you turn around, if all variables are the same as when you left, the system is at steady state.
An example of steady state is a situation in which members of a population die as quickly as new members are born. The birth rate, death rate, and population are always the same, so the system is at steady state.
- Wile, Jay L. Exploring Creation With Biology. Apologia Educational Ministries, Inc. 1998