hi WL,
Do these Black boxes physically exist ?

Or are they just ideal theoretical black boxes.??

E

 

If it is a black box, then you can't know what is inside.

"Black box is a technical term for a device, circuit or a system that is observed in terms of its input, output or transfer characteristics without any knowledge of its internal workings. Black-box modelling usually refers to behavioural modelling of such devices, circuits or systems."
V. Ceperic and A. Baric, "A brief overview of the black-box behavioural modelling of electronic circuits for transient simulations," 2012 Proceedings of the 35th International Convention MIPRO, 2012, pp. 72-77.

Neither does it matter what is inside. The point being that you have to deduce the behaviour through interrogation (testing and observe the results).
Though frequently in simulations devices are treated as "black boxes" in the algorithm of the circuitry. Except we really do know because separate algorithms return the results of any electrical "interrogation". Such as in SPICE modelling of a transistor, for example.

 

Does it's output characteristics include infra-red radiation? If so we can deduce if anything inside is dissipating power as heat.