By Herman Daly
The economic process is not a mechanical analog that can be run forward and backward, nor a circular process that can return to any previous state. Rather it is an irreversible and irrevocable process moving in the direction of time’s arrow of increasing entropy . Finitude and entropy guarantee that the economic life of our species will be a journey of no return. Therefore even a stationary economy, in the classical sense of constant population and constant capital stock, is ultimately a journey of no return, because the metabolic throughput of matter and energy required to maintain constant stocks of people and physical capital, in the face of depreciation and death, is an entropic flow from ever less concentrated sources to ever filling sinks – and both sources and sinks are finite.