Glossary

algorithm  A recipe for performing a function or solving a problem

alife (artificial life) The study of life-like properties in artificial systems

analog/digital Analog processes use "analogies" of physical phenomena (e.g., electrical voltage for the size of a variable), whereas digital procedures represent phenomena that through numbers or symbols. Most computers today are digital, but analog computers are still used.

carbon cycle  The sequence of steps that carbon cycles through an ecosystem. For example, plants fix carbon in their tissues, herbivores eat the plants, carnivores eat the herbivores, and bacteria decompose the dead bodies of carnivores when they die, thereby passing the carbon into the soil so that plants can extract it to begin the cycle of growth again.

chaos  Complex behavior in dynamics systems. One characteristic is sensitivity to initial conditions. That is, small initial differences quickly lead to large differences in behavior. Chaotic systems travel through many states without ever returning to their starting point.

codon  A string of three DNA bases that code for a single amino acid.

computability  The existence of an algorithm to solve a problem.

cyberspace  Thought space, the universe of information and ideas. Derives from Norbert Weiner's term 'cybernetics'. The concept of cyberspace can be compared to the philosopher Karl Popper's idea of a third world.

DNA / RNA (deoxyribose or ribonucleic acid) Formation of patterns or structures by aggregation in which the particles have to diffuse through a medium before sticking to a developing cluster.

DLA (diffusion-limited aggregation) Formation of patterns or structures by aggregation in which the particles have to diffuse through a medium before sticking to a developing cluster.

disorder  The term is used in a fairly precise way by physicists and engineers to mean a system with a lot of inherent randomnesses and therefore low predictability.

dissipative system  A system that exchanges energy with its surrounding areas

domain A logical section or grouping of sites on the Internet, such as a country or a type of organization.

emergence  The appearance of large-scale properties in the self-organizing systems; e.g., seeing the wood for the trees

entropy  A measure of disorder in a system. A fundamental concept in thermodynamics and information theory

environmental gradient  A systematic change of an environmental property. An example is a drop in temperature noticeable as you climb a mountain.

far from equilibrium In thermodynamics, far-from-equilibrium is a state of dynamic equilibrium, in which a system is constantly changing with time due to the input of external energy input. The term was coined in the 1970s by Belgian chemist Ilya Prigogine, who modeled it on Paul Bernard's explanation of  the phenomenon of homeostasis.

fractal  A pattern or process made up of many replicas at different scales. If all are the same it is said to be self-similarity, but if they are the same only on average, it is said to be self-affined.

fractal-scaling  A mathematical term to describe irregular geometrical structures whose shapes appear to be self-similar regardless of the level of magnification at which it is viewed

graph  Mathematicians have a precise meaning for a graph, which is somewhat different from everyday language. A graph is a set of points some or all of which are connected by lines.

homeostasis This self-regulating process was first found in biological systems by the French physiologist, Claude Bernard, in 1865. It occurs when a system maintains a stable internal environment despite the changes present in the external environment. The body maintains homeostasis by controlling a host of variables ranging from body temperature, blood pH, blood glucose levels to fluid balance, sodium, potassium and calcium ion concentrations.

hypercycle  A cyclic pattern of chemical reactions in which each substance catalyzes the formation of later substances. Hypercycles are thought to have played a part in the origin of life.

iteration  Repetition of a process again and again. Fractals are formed by iteration of the same process at ever smaller scales.

loop analysis  This is a method of analyzing the feedback loops in a complex dynamic system by tracing the signs of the interactions.

mapping  A transformation that links input values to output values. For example, adding 1 to any number defines a mapping from each number X to X +1.

non-linearity  The presence of non-linear terms or components in a system or process. Non-linearity is essential for chaos. Interactions in physical systems are often non-linear.

phase-locking  Constructing different processes to cycle in unison; e.g., clocks on a wall interact so that they all keep identical times.

reductionist paradigm  An approach to science in which we try to understand complicated phenomena by breaking them down into simpler parts. For example, to try to understand the human body we look at functions of different organs and muscles.

stochastic  Random values. For example, a stochastic process takes random values at any time.

synergetics  The name Haken gave to a phenomenon in which lots of objects coordinate their behavior and act in unison.