Black box

A black box is a system with where we have a well defined understanding of inputs and outputs, but no idea what's going on inside. The classic black box is a "line replaceable unit," or LRU. Black boxes are usually radios or other auxiliary equipment for a complex engineered system like an airplane or ship. Black boxes speed up repair, because they can be replaced quickly, restoring the big system to service. They also reduce the cost of systems, and increase the quality, by spreading development costs of the type of unit over different models of vehicles.

Black boxes are designed to specifications. The specification defines the inputs and outputs. It also defines the tools to replace the unit (usually nothing more than a #2 Phillips-head screwdriver), and the bulk and weight (they always need to be carried by one man, and fit through a door, if possible). There are also requirements for flammability, unwanted radio emissions, resistance to damage from fungus, static electricity, heat, pressure, humidity, condensation drips, vibration, radiation and other environmental measurements.

Many black boxes for commercial aircraft are designed according to specifications from Airline Radio Incorporated, affectionately called "ARINC." ARINC is a company owned by a number of airlines, that sells specifications and sets standards. Black boxes are also defined by manufacturers like Airbus and Boeing, or various military organizations.

LRUs are painted crackle-black to more efficiently radiate and convect heat away from the unit.

The term is important in philosophical contexts, because various philosophers have proposed [black box theories]? for various fields. Probably the most prominent such theory is the so called black box theory of consciousness, which states that the mind is fully understood once the inputs and outputs are well defined, and generally couples this with a radical skepticism about the possibility of ever describing what goes on inside the mind.

/Talk