Open systems

An open system is a system that exchanges energy, matter, or information with its environment, maintaining its organization not by sealing itself off but by sustaining continuous flows across its boundary. The concept was formalized in general systems theory by Ludwig von Bertalanffy, who argued that living organisms are paradigmatic open systems: they take in nutrients and energy, transform them into structure and function, and export waste and heat. Without this exchange, the system cannot maintain the disequilibrium that makes organization possible.

The distinction between open and closed systems is not binary but a matter of degree and kind. A closed system approaches thermodynamic equilibrium; an open system, driven far from equilibrium by environmental flux, can exhibit spontaneous self-organization — dissipative structures that increase local order at the cost of global entropy export. The Earth's biosphere is the largest open system we know, maintained by the solar energy flux. Understanding any system requires mapping not only what happens inside its boundary but what crosses it: the flows are the system's lifeblood.